Industrial hydraulics-MANUAL.pdf

Electric Drivesand Controls Hydraulics Linear Motion and Assembly Technologies Project Manual Industrial Hydraulics Trainer‘s manual Pneumatics Service RE 00845/04.07 Foreword  Bosch Rexroth AG I RE 00845/04.07 Foreword In July 2004 the Federal Minister for Economics and Labor passed the new regulations for vocational training in industrial metalworking professions. Basic training for the entire field of professions, the structure and objectives of vocational training are set out in paragraph § 3. Skills and knowledge (qualifications) are to be imparted with reference to practical needs. To be capable of carrying out qualified work, the trainees are to be trained in particular in independent planning, execution and checking as well as acting in the overall operative context. Specialist qualification Core qualification Profession-specific specialist qualifications, e.g. the manufacture, assembly and disassembly of assemblies and systems are to imparted in conjunction with core qualifications, e.g. planning and organizing of the related work and the evaluation of work results. The training contents for the profession-specific specialist qualification include, among others, business processes and quality assurance systems in the relevant field of activity. Project Manual The present Project Manual Industrial Hydraulics is intended as accompanying and exercise book to help trainers and technical instructors to impart knowledge through project work. BIBB In line with the exercises compiled by the Bundesinstitut for berufliche Bildung in Berlin BIBB (Federal Institute for Vocational Training in Berlin BIBB) project tasks are described, which are oriented towards the restructured industrial metalworking and electrical engineering professions. Practice-oriented project tasks With all practice-oriented project tasks core and specialist qualifications are imparted in an integrated form involving independent planning, execution and checks. The training course was structured in a way that the project manager/trainer explains the project order first and also supports the trainees during their project work. In the course of the further project tasks, the information and assistance provided by the project manager is reduced. In this way the trainees learn to actively proceed in line with project management requirements. Foreword Notes  Bosch Rexroth AG I RE 00845/04.07 Introduction  Bosch Rexroth AG I RE 00845/04.07 Restructuring of industrial metalworking and electrical professions The increasing importance of process-oriented working procedures, the growing complexity and networking of new technologies as well as comprehensive, customer-oriented services have resulted in the necessity to restructure industrial metalworking professions, which was laid down in regulations in 1987. 1987 2004 3,5 3,5 2 Subject area-specific specialized training Training period (years) Subject area-specific specialized training 3 Profession-specific specialized training 1 Interdisciplinary specialized training Basic training 3 2 Profession-specific specialized training over 21 months, including specialized task in the company’s field of activities Integrated training 1 0 Common core qualification 21 months 0 Restructuring of industrial metalworking professions (source: DIHK 06/2004) Qualification requirements The requirements for core qualification are met by solving tasks set in the form of project steps, which involve informing, planning, decision-making, executing, checking and assessing. Mastering and internalizing the multitude of qualifications finally results in the professional competence to act. Time frame - method (source: DIHT 06/2004) ns at io Synthesis of qualification contents al ns qu ifi ca tio ist ia l ec al qu re - Core qualifications - Specialist qualifications + Fields of activities Sp → Training pattern (technical structure) 2nd step ifi c Analysis of qualification requirements Co 1st step Field of activities → Time frame (time structure) In the sense of fields of work/activities within the context of professionspecific business processes Introduction  Bosch Rexroth AG I RE 00845/04.07 Imparting knowledge through project work The present Project Manual Industrial Hydraulics is intended for imparting the required specialist knowledge in the field of hydraulic control technology in practice-oriented applications. Through the logically structured project work the trainee: Training contents • is to understand the physical laws and technical interrelationships (area, pressure, force, work and power), • is to become able to explain the function, structure, practical operating principle and possible applications of hydraulic equipment, • is to become able to read and understand symbols and circuit diagrams, • is to get to know basic controls of hydraulics and assemble units according to prepared circuit diagrams, • is to be made familiar with types, properties, requirements and application of hydraulic fluids. Framework curriculum The project tasks and project work described in the Project Manual Industrial Hydraulics provide trainers and trainees with information and instruments that will help them comply with the demands made on the transfer of specialist know-how in the field of hydraulics. The sub-objectives listed below, which are taken from the framework curriculum for vocational training of industrial mechanics, are matched with the regulations for vocational training in industrial metalworking professions dated 09.07.2004 (BGBl. I. S. 1502). The sub-objectives listed refer to training objectives given for hydraulic control technology. Industrial mechanics • plan and organize work sequences, check and assess work results, • verify mechanical and physical variables, • assemble and disassemble machines, equipment, fixtures and systems, • commission systems and plants, including open and closed-loop control equipment, and instruct customers, • carry out maintenance work and ensure the operability of technical systems, • prepare technical documentation, • apply standards and regulations for safeguarding the process and product quality and contribute to continuing improvements in the work sequences in the company. Fields of activities Industrial mechanics are mainly assigned to professional activities in the field of production, assembly, maintenance and automation of technical systems. The fields of activities mentioned before are dealt with in individual training sections. Within the fields of activities, the training sections of the individual training years are based on each other. Training sections In training section-oriented lessons the solutions required for project handling are not imparted like in conventional lessons. The solution of the task set is worked out alternately in systematic, technical and situation- or case-related training. In the course of the project work it should be envisaged that the trainee can handle the projects on his/her own and under his/her own responsibility and, whenever possible, in a team. This brings the training contents closer to the trainee's real world of experience, which enables and simplifies imparting the professional competence to act in the lessons. To solve a more complex project task, it may be required to impart the basic principles for this project in systematic technical training. • Executing. They determine the control components to be used and the functional sequence for controls on the basis of circuit diagrams and other documentation for various component technologies. which is geared to hydraulic control technology. The trainees plan and realize the set-up of the control. The individual contents of the training sections are coordinated with the training curriculum for in-company training. is described below.07 Training section 6. energy. they use manufacturers's documents. They document and present their results utilizing suitable user programs. flow • Operating modes • Plant safety Training schedule The starting point of didactic-methodical structuring of the training situation in the individual training sections is to be the business and work process in the vocational field of activities. The technical contents of the individual training sections are formulated generally and are not listed in a differentiated way. . 10/Control technology) Training section 6: Installing and commissioning control systems 2nd year of training Recommended time: 60 hours The trainees are to install and commission control systems. For this. • Deciding. They commission the control system observing rules for safety at work. The objectives of the training sections are the decisive factors for the structuring of the lessons and represent the minimum scope together with supplementary contents. (Training framework curriculum § 10 section 1 No. Contents: • Technology diagram • Hydraulic power part • Supply unit • Sensors • Flow of material. in particular. information • Electrical circuit diagrams • Pressure fluids • Pressures.Introduction  Bosch Rexroth AG I RE 00845/04. where practical requirements necessitate this deviation. • Checking. • Evaluating. velocity. The project tasks described in the Project Manual Hydraulics are structured so that the trainee achieves the training objectives described in the project definition in 6 project steps: • Informing. They develop strategies for troubleshooting and optimization of the control systems and apply them. According to § 7 of the regulations for vocational training in industrial metalworking professions deviations from the training curriculum are permitted in terms of technical contents and time schedule. This is reflected in the formulation of objectives in the individual training sections. forces. • Planning. The trainee will develop his or her competence to act from the capability and willingness to solve tasks and problems and evaluate results in a target-oriented manner. This is valid. Informing Based on the project definition. Decision-making After the planning stage. The documentation should also be finally corrected. Moreover. the result can be compared with the manufacturer's documents. He/she decides on the sequence and the interrelationships of the individual project steps. if required. taking all safety notes into account. This also includes the preparation of a final report. Possible questions: • What is to be done? • Have I understood the task completely? • Which hydraulic component/system is to be dealt with? 2. which data sheets are required for coping with the project task. Possible questions: • Have I chosen the correct sequence? 5. for example. the trainee is to get a clear idea of the finished solution. a decision should be made as to whether it would be easier to solve the project task in a team. by asking questions. This is achieved through a systematic analysis of the project documentation and. including any required details. whether the measured results are realistic. After completion. and finally the result of the customer requirement. 1. the trainee determines the aids to be used. After a thorough preparatory phase. it should be verified or questioned.Introduction  Bosch Rexroth AG I RE 00845/04. Checking: The trainee must check intermediate results as early as during the execution stage. Possible questions: • Which hydraulic components will be used? • How can you know that technical data sheets are up to date? • Have I utilized all available sources of information? • Are the prescribed safety instructions at hand? 4. Depending on the project order. in the case of costly work in the field of information technology. the possibilities of execution may be limited. skillfully.g. Possible questions: • • • • How to proceed? What knowledge is required? Which aids are available? Are there comparable applications in my company? 3. Executing: The order is to be executed according to the work instructions given in the chapter "order execution". it must be checked. . In detail. Professional competence to act The projects described in the project definition are oriented towards practical needs and are characterized by a high level of conformity with customer orders from industry and trade. Planning Planning means the theoretical preparation and anticipation of the concrete execution. the trainee is to work off the project task or the project order in 6 steps. planning requires competence to handle the project order and to organize the project handling steps. methodically and independently on the basis of technical knowledge and skills. the trainer makes a final check. improved and completed. the trainee is to carry out the project order largely on his/her own. In some cases. whether the right attempt at a solution was selected. e.07 Specialist competence The objectives described are geared to the development of competence to act. In the case of measuring exercises. As mentioned before. After the solution was worked out in writing. Customer orders represent complete activities and develop and promote the trainee's professional competence. Procedural knowledge In this manual. The evaluation can be finalized in a technical discussion. executing and checking according to the regulations for vocational training in industrial metalworking professions. project managers. how the learning target can be reached. It is the knowledge of how to achieve a certain result with which measures. The trainee must learn to assess his/her strengths and weaknesses and develop objective quality standards for his/her acting.Introduction  Possible questions: • • • • • Bosch Rexroth AG I RE 00845/04. . we refer exclusively to trainees and trainers in the present manual. an external or self-evaluation is to be carried out on the basis of a comparison of project order documents. the installed control and results of measurements and checks.07 Was the control properly installed? Has the project objective been complied with? Is the customer satisfied with the project result? Which documentation is required? Is the result completely documented in the correct order? 6. which are used as recurrent symbols.. are to transfer important information as quickly as possible in the form of a simplified graphical representation and independently of languages. possibly also in a discussion with the customer. The present manual must be understood as a tool for providing the required core and specialist qualification that must be imparted in an integrated form through independent planning. and their causes must be analyzed and possibilities discussed as to how faults can be avoided in the future. procedures or processes . whether male or female. Evaluating: In the final evaluation phase. if any. we do not give notes on procedural knowledge (explanatory knowledge). General notes: For didactic reasons. We expressly point out that these terms include all persons involved in the basic and advanced training: Instructors. which ultimately leads to personal competence. etc. teachers.in this case. Faults. Pictogram The pictograms. lowering of the load at adjustable lowering speed by means of a shut-off valve. pilot operated Protection of a vertical cylinder with suspended load by means of a pilot operated check valve. adjustable Powering a conveyor belt by means of a hydraulic motor with adjustable output speeds for both directions. 02 Hydraulic pump. direct operated Preparation of a characteristic curve for the pressure/flow relationship.Introduction  Bosch Rexroth AG I RE 00845/04. . 15 Pressure switch Hydraulic pressing of two workpieces with monitoring by a pressure switch. parallel circuit) on punching equipment. 09 Throttle valve. 13 Pressure relief valve. 11 Flow control valve Rotary drive (hydraulic motor) with constant speed. 07 Check valve Protection of a vertical cylinder with suspended load in a welding in a welding fixture by means of a check valve. adjustable lowering speed. Application of different types of hydraulic cylinders. 10 Throttle check valve Traversing a tool carriage at different speeds. When a tool change takes place. pressure intensification Safety aspects when using a single-rod cylinder and a meter-out throttle. flow Different traversing speeds when extending and retracting a single-rod cylinder. No. 04 Single-rod cylinder. charac. 06 4/3 directional valve Controlling the direction of a single-rod cylinder by means of a 4/3 directional valve. Project designation Industrial application (example) 01 Hydraulic power unit Pressure oil supply to a hydraulic cylinder by a hydraulic power unit.07 Project designation with short description of the industrial application The knowledge of basic principles of hydraulic control technology is to be imparted with relation to practice. 12 Pressure relief valve. 05 Hydraulic motor Powering a hoist with the help of a hydraulic motor for lifting and lowering of a load. 03 Single-rod cylinder. Opening the check valve by means of a 4/2 directional valve. controls Electrical pre-selection of various pressures (series. Possible use of direct operated pressure relief valves.Typical features of a pressure-compensated vane pump.g. Together with the customer requirements the detailed project definitions are finally intended to make the function and possible applications of individual system components clear to the trainee during processing of the order. 14 Pressure reducing valve Swiveling a clamped workpiece by means of a hydraulic motor. teristic curve Understanding the control behavior with the help of a characteristic curve. 08 Check valve. e. The trainer can impart the basic knowledge of hydraulics in 21 individual projects. Rating of a simple power unit on the basis of parameters specified by the customer. Properties of different directional valve spool shapes and symbols. for an advance movement. It should be possible to position the cylinder at any position. 18 Regenerative circuit Increasing the velocity by using the oil returning from the single-rod cylinder for extending.. hydraulic systems in everyday work.07 16 Pressure switch. Observing regulations. . 20 Valve by-pass control 21 Commissioning. 19 Rapid speed/creep speed Rapid speed/creep speed control for lifting a pallet onto a control conveyor belt at load-independent. Lifting and lowering of a load by a single-rod cylinder. safety rules and generally recinspection. 17 Hydraulic accumulator Moving the tool from the working range of the machine tool using the oil volume stored in the hydraulic accumulator.Introduction  Bosch Rexroth AG I RE 00845/04. which is controlled by a 4/3 directional valve with blocked central position. Sparing of the hydraulic pump and energy savings through by-pass circuit. adjustable creep speed and with fastest return stroke possible. ognized technical rules when handling production and .. hysteresis Working out the hysteresis of a mechanical pressure switch. maintenance. flow possible from both sides C1 09 Throttle valve. negative load C1 08 Check valve. pilot operated Check valve.2 05 Hydraulic motor Lifting platform drive B2 06 4/3 directional valve Control of direction. troubleshooting. single-rod cylinder B3 07 Check valve Protection of a hydraulic cylinder.1 04 Single-rod cylinder/flow Traversing speeds B 1. maintenance H1 13 E 1. recommended and published by the Bundesinstitut für Berufsbildung (BIBB).07 Comparison of project exercises of Bosch Rexroth AG/BIBB The comparison below refers to the BIBB training course Hydraulics. lifting of a pallet G2 20 Valve circulation control Lifting and lowering of a load G3 21 Commissioning Commissioning. Project no.Introduction  Bosch Rexroth AG I RE 00845/04.2 . Project designation Project content BIBB 01 Hydraulic power unit Component selection for hydraulic power unit A1 02 Hydraulic variable displacement pump Pump characteristic curve A2 03 Single-rod cylinder/pressure Safety aspects with regard to pressure intensification B 1. adjustable Conveyor belt drive D1 10 Throttle check valve Traversing an advance slide D3 11 Flow control valve Tool drive D2 12 Pressure relief valve Characteristic curve Pressure relief valve controls Pressure pre-selection on punching equipment E1 14 Pressure reducing valve Tool advance E3 15 Pressure switch Workpiece pressing with monitoring E4 16 Pressure switch hysteresis Characteristic curve E4 17 Hydraulic accumulator Storing energy in view of a hydraulic pump failure F1 18 Regenerative circuit Increasing the velocity by using the returning oil flow G1 19 Rapid speed/creep speed control Production line. . • Optionally. 04 and 05 – 1 flowmeter DZ 30.1 1 Hydraulic hose/minimess connection 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 2 2 2 2 2 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 3 3 1 1 3 3 2 1 2 1 2 3 1 4 3 3 3 4 3 4 1 3 3 3 4 3 3 3 4 3 4 1 3 3 3 1 1 2 2 1 2 3 3 3 4 1 1 3 3 3 4 Note on the utilization of the matrix: • The table shows the number of hydraulic components required for each exercise.2 Throttle check valve DF 3 Flow control valve DD 6.1 1 Shut-off valve DD 1.3 Double-acting cylinders ZY 1.1 Pressure relief valve DD 2 Pressure reducing valve DF 1.1 Check valve DS 1.Introduction  Bosch Rexroth AG I RE 00845/04.2 Hydraulic accumulator DE 2 Limit switch DZ 4.2 1 Throttle valve DZ 2. pilot operated DZ 2.07 Component matrix The matrix below provides an overview of the components.4 1 Pressure gauge/minimess connection DZ 25.Load Double-acting cylinders with load DM 2. the following is required additionally: – 1 stopwatch for projects 02.1 2 Distributor plate DZ 1. Project 01 02 Component designation ZY 1.N Hydraulic motor DW 3E 4/2 directional valve C DW 4E 4/3 directional valve G DW 10E 4/3 directional valve J DW 13E 4/3 directional valve E DS 2.1 Check valve.N for projects 04 and 06 – 1 tachometer in project 05 and – 1 Multihandy (electronic measuring transducer) 5050 for acquiring the values of the flowmeter (measuring turbine) and the tachometer. which are required for the individual project exercises.E Pressure switch DZ 3. pilot pressure enables flow in both directions DS 1.T.1 Direct operated pressure relief valve.1 . T. flow possible in only one direction. with spring. actuated by turning DZ 2.1 Pilot operated check valve. rest position closed. spring return DW 3E 4/3 directional valve with direct actuation by two solenoids.1 Shut-off valve. cracking pressure 1 bar DS 2. B DW 4E 4/3 directional valve with direct actuation by two solenoids. spring centering of the central position and central position P. A.Introduction 10 Bosch Rexroth AG I RE 00845/04.3 Double-acting cylinder with single-sided piston rod with load ZY 1. A.Load Fixed displacement motor with external leakage line and two directions of rotation DM 2.07 Overview of components Symbol Component designation Type designation Double-acting cylinder with single-sided piston rod ZY 1. A -B-T DW 10E 4/3 directional valve with direct actuation by two solenoids. spring centering of the central position and central position P .N t 4/2 directional valve with solenoid actuation. B DW 13E Check valve with spring. the cracking pressure can be adjusted by means of a spring DD 1. spring centering of the central position and central position P. for one direction of flow.4 Hose with quick release coupling with check valve DZ 25.2 Pressure gauge with hose and quick release coupling without check valve DZ 1.Introduction 11 Bosch Rexroth AG I RE 00845/04. largely independent of viscosity and pressure differential. adjustable. adjustable DD 6E Throttle valve.07 3-way pressure reducing valve DD 2 Pressure switch. adjustable. adjustable DF 1. electromechanical.2 Throttle check valve.2 2-way flow control valve. adjustable. free flow in one direction DZ 2. with by-pass check valve DF 3 Accumulator safety block for diaphragm-type accumulator DZ 3.1 Hose VSK 1 . 2 .1 Flow-meter DZ 30 Tachometer 1) red black Limit switch. inductive blue 1) Stopwatch 1) No symbol according to DIN ISO 1219 DE 2.Introduction 12 Bosch Rexroth AG I RE 00845/04.07 Distributor plate with four ports DZ 4. safety regulations.04 • Operating instructions DS4 – 1X RE 00225-B/05. Warning This symbol refers to a potential risk. Only in this way can optimized and low-priced solutions be found. Corresponding notes on the handling of electrohydraulic components and systems of Bosch Rexroth can be found in: • General product information on hydraulic products RE 07008/02. In order that hazards to plant and machinery can be recognized.05 • Operating instructions for hydraulic systems AB 01-01. . Note: The electrohydraulic components and systems described in this Project Manual are technical equipment. The described precautions for averting risks must be taken. they are a quality feature. at the product concept stage.07 Safety aspects Safety and the economic use of resources are essential demands that are placed on modern plant and machinery and serve to protect people. The use for the intended purpose also includes that the safety regulations. product information brochures and operating instructions must be observed. safety notes and product information are observed can the trouble-free operation of Rexroth products be ensured. The present Project Manual Industrial Hydraulics includes warning notes.02 • Hydraulic cylinders of tie rod/mill-type design (operating instructions) RE 07100-B/10. which precede instructions for activities that involve a risk of personal injury or damage to property. product information and operating instructions described in the following are read and understood. which can lead to light or serious injuries or damage to property.Introduction 13 Bosch Rexroth AG I RE 00845/04. Safe machines with low consumption demonstrate that the manufacturer masters his processes. Conventions This symbol refers to imminent danger that. can lead to severest injuries or death. Caution This symbol refers to supplementary information. that is.05 The safety notes and product information in the above documentation are exclusively valid for Bosch Rexroth hydraulic products. which is not intended for private use. Only when operating instructions. if not avoided. These two requirements have in common that they have to be taken into account as early as possible. . A specialist must observe relevant technical rules. unless the use of other hydraulic fluids is expressly permitted in the operating instructions. If Projects 01 to 21 described in the Project Manual Industrial Hydraulics are carried out on training stands and with electrohydraulic components that were not delivered by Rexroth. who. product information documents* and operating instructions must be handed over or be accessible to the trainee in their latest issue. When using competitors' products. The correct handling of hydraulic fluids and possible risks as well as measures for averting risks are described in a separate topic "Hydraulic fluids" in the following. products of competitors' make. commissioning and operation. that is. In order to ensure operational safety. these activities may only be carried out by a corresponding specialist or by an instructed person under the supervision of a specialist. Note: The required safety regulations.Introduction Qualification of personnel 14 Bosch Rexroth AG I RE 00845/04. Consequently. any liability claims for defects or other liability claims vis-à-vis Bosch Rexroth AG become void. The corresponding information can be found in the safety data sheet. disassembly. this means that the trainer must point out potential risks to the trainees and provide information on how to avert such risks. including danger to life! In the case of damage resulting from improper use and unauthorized interventions. upkeep and maintenance require fundamental knowledge of mechanics and electrohydraulics as well as the knowledge of related technical terms. due to his/her professional training. recognize potential risks and take suitable precautions. Warning Liability Work carried out improperly on electrohydraulic components and systems involves the risk of injury and represents a safety risk during operation of the system. any defect or liability claims vis-à-vis Bosch Rexroth AG shall be void as well. observe the safety notes of the manufacturer and make sure that the components and systems comply with currently valid EU Directives. which are not provided in the Project Manual Industrial Hydraulics. In the Project Manual Industrial Hydraulics we do not refer in detail to the correct handling of hydraulic fluids in the project exercises 01 to 21. can asses the duties assigned to him/her. commissioning is prohibited until it was established that the electrohydraulic components and systems to be used meet the stipulations Warning of all relevant EU Directives. A specialist is.07 Installation. For this reason. his/her knowledge and experience and the knowledge of relevant regulations. which are operated with hydraulic fluids based on mineral oil. * Rexroth product information sheets are valid exclusively for hydraulic products. they complement each other and are also combined. Source of energy (drive) Hydraulics Pneumatics Electrics Mechanics El. motor to hydraulic motor 1:10 Volume and assignment of required installation space is often less favorable than with hydraulics Good via pressure and flow Good to excellent Poor Large forces Small installation space requirement Smooth control (accelerating. requires detailed knowledge of the features and also of the pros and cons.Basic principles of hydraulics  Bosch Rexroth AG I RE 00845/04. decelerating) Excellent via pressure and flow Motion types of drives Linear and rotary movements can easily be achieved with hydraulic cylinders and hydraulic motors Electrical open and closed-loop control Comparison of system technologies Linear and rotary movements can easily be achieved with pneumatic cylinders and pneumatic motors Mainly rotary movements Linear and rotary movements . motor Mains El. or a combination. vehicle and aircraft engineering. motor El. The decision in favor of a certain system. If we speak of hydraulics in mechanical. pneumatics. to the science of still and moving fluids (hydrostatics and hydrodynamics). shafts. derived from the Greek word hydro = water. on the other hand. we understand by this the practical application of this discipline of physics in the fields of power transmission and open and closed-loop control technology. power/weight ratio of el. in a scientific sense. motor Combustion engine Combustion engine Battery Combustion engine Pressure vessel Weight Tension force by spring Energy transmission elements Pipes and hoses Pipes and hoses Electric cables Mechanical parts: Levers. Comparison of systems System technologies such as hydraulics. refers. Magnetic field Energy carriers Fluids Air Electrons Rigid and elastic bodies Force density (power density) High Relatively low Low High High pressures Low pressures cf. electrics/electronics and mechanics compete with each other as means for the transmission of power.07 Basic principles of hydraulics Introduction Hydraulics. etc. Basic principles of hydraulics  Bosch Rexroth AG I RE 00845/04. since hydraulic components are lubricated by the operating medium • Long service life • Possibility of energy recovery • Pressure and flow losses (fluidic friction) in line systems and control elements • Dependence of viscosity of the hydraulic fluid on temperature and pressure • Leakage problems. if the system planner knows the typical features offered by hydraulic control technology. Features of hydraulic systems • Transmission of large forces within a minimum of space.07 System planning The specific advantages of hydraulic technology over other technologies such as pneumatics. electrics and mechanics. therefore risk of accidents and risk of fire • Compressibility of the hydraulic fluid . can only be utilized to the full extent. forces and moments • Good monitorability of occurring forces • Swift reversing operation due to small masses (low moments of inertia) of the drive elements • High switching dynamics • Good transmission ratio • Simple conversion of rotary movements into linear movements or vice versa • Constructive flexibility in the arrangement of components • Physical separation of input and output through pipes and hoses • Possibility of automating all types of movements and auxiliary movements by means of pilot control valves and electronic command transmission • Usability of standard components and assemblies • Simple overload protection • Low wear. • High energy density • Storing of energy is possible • Stepless changes in motion variables such as velocities. measuring and testing instruments are required. . an oil-hydraulic system firstly converts mechanical energy into hydraulic energy.07 Hydraulic systems convert mechanical energy into hydraulic energy. The components used in hydraulics can be classified according to their function.Basic principles of hydraulics Energy conversion  Bosch Rexroth AG I RE 00845/04. closedloop control Energy conversion Hydraulic pump Hydraulic open and closed-loop control valves Hydraulic cylinder. and hydraulic cylinders and hydraulic motors on the secondary side. and in its magnitude and direction of action by open and closed-loop control valves. among others. combustion engine. Hydraulic energy and hence the transmitted power can be influenced in pressure and flow by hydraulic pumps. For storing and maintaining the hydraulic fluid. coolers. additional equipment such as reservoirs. the energy transport. thermal energy. heaters. filters. hoses and bores in control blocks or manifolds assumes. transport it in this form in an open or closed-loop controlled way and then re-convert it into mechanical energy. and then converts it into mechanical work. mechanical energy Hydraulic energy Working element to be actuated Mechanical energy Energy conversion in a hydraulic system As illustrated in the schematic above. For the conversion of energy. hydraulic pumps are used on the primary side. Drive Electric motor. transports it in an open or closed-loop controlled way. The hydraulic fluid that is directed via pipes. hydraulic motor Electric energy. manual drive Hydraulic system Drive Energy conversion Open. 07 The figure below schematically shows the components of a simple hydraulic system.Basic principles of hydraulics  Bosch Rexroth AG I RE 00845/04. Hydraulic cylinder Throttle check valve Directional valve Check valve Pressure relief valve Return line filter Hydraulic pump Section circuit diagram of a hydraulic system . Basic principles of hydraulics  Bosch Rexroth AG I RE 00845/04.07 Instead of sectional drawings. More detailed information is provided in the next chapter "Symbols". Symbol circuit diagram of a hydraulic circuit . standardized symbols according to DIN ISO 1219 part 1 are used in hydraulic circuit diagrams. flushing line. DIN ISO 1219-1 The symbols included in standard DIN ISO 1219 should preferably be used. motor) Adjustability of a pump/motor Direction of action of the hydraulic force .fluid power technology. Graphical symbols help to identify the function in circuit diagrams of fluid power technology. and servicing.Basic principles of hydraulics  Bosch Rexroth AG I RE 00845/04. energy is transported within a circuit by a pressurized medium (liquid or gaseous) and open or closed-loop controlled. DIN ISO 1219-2 Basic symbols The basic rules for the preparation of hydraulic circuit diagrams are determined in part 2 of standard DIN ISO 1219. They can also be attached to the components themselves for this purpose. venting line The crossing of two lines without connection point indicates that there is no connection The connection of two lines is represented by means of a connection point. The followings lists are not complete. but their use does in no way rule out the use of symbols commonly applied in other technical areas for identifying pipes and hoses.uncertainties and faults at the planning stage. Hose Function unit for valves having a maximum of four service ports Frame for energy conversion unit (pump. but must be regarded as working aid for the preparation or completion of project-related circuit diagrams. frames for components and symbols Internal and external pilot line. return flow line. graphical symbols and circuit diagrams. The graphical symbols used in the manual comply with DIN ISO 1219 .07 Symbols according to DIN ISO 1219-1 In fluid power systems. installation. compressor. Supply line. leakage line. Circuit diagrams are a tool to simplify the planning and description of a hydraulic system in order to prevent .through a standardized representation . part 1: Graphical symbols. during production. Basic principles of hydraulics Overview of symbols  Bosch Rexroth AG I RE 00845/04. part 1 (excerpt) .07 Directional valves Pressure control valves Flow control valves Check valve Pressure relief valve Throttle valve/orifice Directional poppet valve Pressure reducing valve Two-way flow control valve Directional spool valve Sequencing valve Overview of symbols according to DIN ISO 1219. and gears for mobile applications. the hydraulic pumps usually aspires hydraulic fluid through the suction pipe. Typical features of the open circuit: • The hydraulic pump aspires oil directly from the hydraulic tank. for example. • large space requirement. • contamination can settle in the hydraulic tank. we differentiate between three circuit systems: • Open circuit. • large amount of fluid. • semi-closed circuit. • large hydraulic tank required. press controls. Open circuit In an open circuit. • unfavorable volumetric efficiency Input speed n = constant Schematic diagram Lifting speed v = constant Flow qV = constant The open circuit is employed. this means. • the hydraulic fluid flows via control elements to the actuator. in machine tools. • better cooling. winch drives. • closed circuit. • the hydraulic fluid flows from the actuator back to the hydraulic tank. . • simple structure. The actuators can be hydraulic cylinders and hydraulic motors.Basic principles of hydraulics Hydraulic circuit systems  Bosch Rexroth AG I RE 00845/04. there is no connection between the suction pipe of the hydraulic pump and the hydraulic fluid returning from the actuator. handling systems. The hydraulic fluid is directed by directional valves to the actuator and fed back to the storage reservoir.07 In the field of hydraulics. which is installed below fluid level. • good volumetric efficiency. smooth running. the hydraulic fluid returning from the actuator is directly re-fed to the hydraulic pump. • sensitive to contamination Schematic diagram Auxiliary pump for leakage compensation Flow qV = variable Output speed n = variable Cooler The closed circuit is used almost exclusively in mobile applications. Typical features of the closed circuit are: • The hydraulic fluid is fed by the pump to the actuator. The design-inherent permanent. the hydraulic fluid remains in the circuit.07 In a closed circuit. • complicated structure. . • good controllability. The hydraulic pumps and hydraulic motors used are in most of the cases axial piston units. for powering a wheel loader travel drive. e. internal leakage of the hydraulic pump and the hydraulic motor is compensated for by a separate auxiliary pump. which is flange-mounted to the hydraulic pump in most of the cases. • compact design. The high-pressure side of the system is protected by a pressure relief valve. that is.Basic principles of hydraulics Closed circuit  Bosch Rexroth AG I RE 00845/04. • greater stressing of the oil. • the hydraulic fluid flows from the actuator directly back to the pump. The pressure is unloaded to the low-pressure side. • silent.g. • The specified travel speed of the actuator can be influenced by means of a flow control valve. for example. Hydraulic accumulators can be provided for realizing faster movements. start and stop are controlled by directional valves.controlling . .07 Semi-closed circuit The semi-closed circuit is a combination of the open and the closed circuit and is used. Heat exchangers optimize the oil quality and hence the availability of the system. drive and control The schematic illustration "drive and control / driving .Basic principles of hydraulics 10 Bosch Rexroth AG I RE 00845/04. • Optimized system technology includes monitoring elements such as pressure switches and pressure gauges. if the volume must be balanced by means of anti-cavitation valves. when a single-rod cylinder is employed in a mobile machine. • The direction. • The travel speed of the actuator is realized by the hydraulic pump flow.and moving" on the next page shows the task set to a hydraulic cylinder or hydraulic motor as machine element. • The required force can be varied by adjustable pressure control valves. controlling and moving * Rexroth-specific statement Driving machines and systems Hydraulic cylinders and motors as machine elements Driving and controlling hydraulic cylinders and motors Flow Pumps + storage tank Hydraulic fluids Direction + position are to be controlled Start – direction – stop Directional seat valves Spool. poppet and isolator valves The required force is to be adjustable Pressure Pressure control valves limit – reduce – switch The required velocity is to be adjustable Velocity Flow control valves Throttles – orifices System technology optimized to suit the specific application Demands made on hydraulic cylinders / motors as drive elements Power units & accessories – accumulators – pressure switches – pressure gauges – heat exchangers .07 drive and control * driving.Basic principles of hydraulics 11 Bosch Rexroth AG I RE 00845/04. the higher the pressure. This means that a greater force (load) generates a higher pressure. It was named after Blaise Pascal. the greater the area. whereas with decreasing force (load).1 MPa = 1 bar = 1. Pascal's law: p= F A or: A= F p F = pA Force = pressure • area F p A Pascal is the SI unit of pressure. where one Dekapascal corresponds to 0.000.07 Physical basic principles Pascal's law Pressure (p) in the vessel results from force (F). and. The second relationship lies in the size of the area (A).000 Pascal (105 Pa) 1 bar = 10 N/cm2 In pressure calculations.Basic principles of hydraulics 12 Bosch Rexroth AG I RE 00845/04. of course. the pressure falls. where: 1 bar = 100.1 mbar. vice versa. 1 Pa = 1 kg m • s 2 = 1 N/m2 The force in Newton per surface area of one square meter. onto which the force acts. the smaller the pressure. which acts on the piston.000 Pa = 0. the pressure is dependent on the amount of the effective force (F) and the size of the area (A) onto which this force acts. The smaller the area. Consequently.000 mbar 1. the unit Dekapascal (daPa) is often used. 100 Pa = 10 daPa = 1 haPa = 1 mbar 100.000 Pa = 1 MPa = 10 bar = 1 N/m2 . A2) have different sizes. Consequently: Example: Area A1 Area A2 Weight force F1 Weight force F2 F1 • ϕ = F2 Solution: = 50 cm2 = 750 cm2 = 1.000 daN = ? F1  750 cm2 1.000 daN  15 = 15.000 daN This means that cylinder 1 with a force of 1. can hold cylinder 2 with a load of 15.07 In a closed system with two cylinders of different size. the loads (F) acting on the areas must consequently be different. Cylinder 1 means: p= F1 Cylinder 2 means: p= F2 A1 A2 F1 If p is identical in both cylinders.000 daN  or with ϕ = A2 = F2 A1 50 cm2 A2 A1 = = 15.000 daN.Basic principles of hydraulics Force transmission 13 Bosch Rexroth AG I RE 00845/04. only one pressure (p) can prevail. which corresponds to a mass of 1.000 kg or 15 t.000 kg.000 daN 750 = 15 50 F1 • ϕ = F2 1. this means: F1  Rearranged by force: A2 A1 = A1 F2 A2 A2 = F2 A1 is the area ratio of the cylinders and is identified by letter ϕ. If both cylinders are to be held in balance and the areas (A1 . F1 F2 A1 A2 . due to dirt? Example: pK = 100 bar ϕ = 2 : 1 ϕ= AK AR Solution: pK  ϕ = pR 2 100 bar  = 200 bar 1 pR = 200 bar Conclusion: Meter-out throttling involves the risk of pressure intensification! ASt AK pK pR AR . Which risk arises.07 The extending speed of a piston is to be adjustable by means of a meter-out throttle.Basic principles of hydraulics Pressure intensification 14 Bosch Rexroth AG I RE 00845/04.g. e. when the throttle is completely closed. The fluid is fed to the system at zero pressure. the piston displaces fluid into the system. we also speak of displacement. If there is no counterforce (counterpressure). Only when the displacement is opposed by a resistance (directional valve. The pump continues to displace fluid and compresses the fluid. In conjunction with pumps. almost no pressure will consequently build up in the pump. The pump only displaces fluid into the system. The following formula is applied for determining the power: qV = Vg  n 1. cylinder piston or similar elements). Pressure builds up. which depends on the resistance not generated by the pump.000 in l/min Vg = displacement in cm3/rev n = speed of the pump shaft in min-1 (rule of thumb without consideration of the volumetric efficiency). If in the schematic diagram below the lever of the pump is shifted to the right. can a counterforce be generated. throttle. . qV in l/min t in s s in mm A in cm2 qV in l/min V As = t t qV = A  v  6 in l/min qV = A in cm2 s v = = Velocity in m/s t s in mm A in cm2 v in m/s In technical data sheets. the size of the pump is given in cm3/revolution. The unit commonly used in industrial hydraulics is l/min.Basic principles of hydraulics Flow 15 Bosch Rexroth AG I RE 00845/04.07 The flow is the amount of fluid (nominal volume) that moves in a hydraulic systems within a certain time. This means that the flow velocity of the fluid must increase at the narrow point.Basic principles of hydraulics Flow law 16 Bosch Rexroth AG I RE 00845/04. Flow q is fluid volume V divided by time t qV = V t Fluid volume V is the product from area A times distance s If A • s is subsituted for V.07 The identical volumes flow through a pipe with different cross-sections within the same time. Flow Flow q in L/min is the same at any point in a pipe. If the pipe has two cross-sections A1 and A2. q1 = q2 q1 = A1 • v1 q2 = A2 • v2 This results in the following continuity equation A1 • v1 = A v 2 = v1 1 > v1 A2 A2 • v2 . q is then given by qV = Distance s divided by time t provides velocity v V=A•s As t v= s t Flow q hence equals the product from the cross-sectional area of pipe A multiplied by the velocity of the fluid v qv = A • v. corresponding velocities must occur at the two cross-sections. This means that certain demands must be placed on the fluid.07 Hydraulic fluids General In a hydraulic system. plastics. The fluid should: – be incompressible for the transmission of forces – dissipate heat that is generated – not change its viscosity at different temperatures – carry away abrasion from hydraulic components – be easy to filter – be neutral against metal guides. good shear stability .Basic principles of hydraulics 17 Bosch Rexroth AG I RE 00845/04. seals and paints – feature good lubrication properties – be resistant to aging – not be detrimental to health – be easy to dispose of after use Environmentally friendly Neutral against seals. paint Corrosion protection Good lubrication properties Good dirt transportation capacity Temperature stability Resistant to aging Demands made on hydraulic fluids Not detrimental to health No tendency towards foaming Good air separation capacity Neutral against bearings. the fluid assumes the task of force transmission. 07 Requirements of the market None of the fluids offered on the market today can meet all of the requirements listed on the previous page. Viscosity data indicate whether a pressure medium is light or viscous at a certain temperature and hence whether friction between the fluid layers is smaller or greater. hydraulic. . hydraulic fluid temperature and viscosity range. It changes as temperature changes. The hydraulic fluid to be used is selected according to the prevailing operating conditions such as: • Operating temperature range • Concept of the hydraulic system • Hydraulic pump type • Working pressure and environmental requirements • Operating time and availability • Economic and ecological factors Viscosity Viscosity is the most important criterion for the selection of the hydraulic fluid.in the section Technical data. The viscosity is measured in the SI unit mm2/sec.Basic principles of hydraulics 18 Bosch Rexroth AG I RE 00845/04. mineral oil is still the most common hydraulic fluid used in hydraulic systems. you can find details about the hydraulic fluid. it is important to take minimum and maximum viscosity values into account that are given by the manufacturer in his documentation for the hydraulic components used. Here. indicates the data for the selection of the hydraulic fluid in the technical data sheet of the component . The component manufacturer Rexroth.RE data sheet . the hydraulic fluid must be taken into account at the planning stage. for example. and during engineering and commissioning of hydraulic systems. Even in view of ongoing discussions about environmental compatibility of hydraulic fluids and in spite of all concerns. the representation in the change in viscosity in dependence upon temperature T shows a straight line. Selection criteria Being an important design element and machine element. In a diagram with a double logarithmic scale for the viscosity axis. Manufacturer's data For determining the application limits of a hydraulic system and consequently for the selection of the hydraulic fluid. USDA and NSF classification DIN 51 524 ISO/DIS 11158 Containing water HL HLP HLPD HVLP HVLPD HH HL HM HR HV HS HG HFAE HFAS HFB HFC Source: Specialist magazine 0 + P Water-free HFDR HFDU Waterinsoluble Watersoluble HETG HEES HEPR HEPG HSF H1 NSF H2 Basis white oil Basis white oil Basis PAO Basis PAO Basis mineral oil . ISO/CD 12922.USA VDMA sheet 24568. ISO 6743/4. STOU Hydraulic oils based on mineral oils Flame-retardant hydraulic oils Fast bio-degradable hydraulic oils Hydraulic oils compatible with foodstuffs DIN 51 502. report. DIN 51 502.Basic principles of hydraulics 19 Bosch Rexroth AG I RE 00845/04. ISO 6743/4 7. ISO 6743/4 and ISO 15380 FDA.07 Classification of hydraulic oils Hydraulic oils Hydro-kinetic application DIN 51 502 ISO 6743/4 ATF HA HN Hydrostatic application Mobile hydraulics: UTTO. Lux. Factory Mutual . 07 Classification of hydraulic fluids based on mineral oil Code letter according to DIN 51 502 and ISO 6743/4 Class L: Lubricants. which require additives for the reduction of wear. good water separation capacity -10 to 90 °C HM Mineral oils of type HL with active additives to improve wear protection in the mixed friction area Hydrostatic drives with high thermal stress. Class H: Hydraulic systems Code letter (symbol) DIN Code letter (symbol) ISO-L Composition Typical properties Field of application Operating temperature HH Mineral oils without active additives (base oils) Hydraulic systems without specific requirements (only in rare applications today) -10 to 90 °C HL Mineral oils with active additives to increase the resistance to aging and to improve corrosion protection Hydrostatic drives with high thermal stress. -- HL HLP (HLPD) HLPD Source: Specialist magazine 0 + P .Basic principles of hydraulics 20 Bosch Rexroth AG I RE 00845/04. e. industrial oils and related products. which require EP/AW additives. DD additives hold contaminations in balance. low velocities -30 to 120 °C -- Mineral oils of type HM with detergent / dispersive (DD) additives. DD additives reduce friction values Hydrostatic drives with high thermal stress. hydrostatic drives in mobile hydraulics -35 to 120 °C -- HS Synthetic fluids without specific flame-retardant properties Special applications in hydrostatic systems -35 to 120 °C HG Mineral oils of type HM with active additives to improve stick-slip characteristics Hydrostatic systems with plain bearings at intermittent. in machine tools and mobile systems. good water separation capacity -20 to 90 °C -- HR Mineral oils of type HL with active additives to improve viscosity / temperature characteristics Extended operating temperature range when compared with HL oils -35 to 120 °C HVLP HV Mineral oils of type HM with active additives to improve viscosity / temperature characteristics Among others.g. industrial hydraulics esters. Polyalpha olefins (synth. synthetic. flame-retardant hydraulic fluids HFD-R Lubrication and control of steam turSynthetic fluids based on phosphate bines. for synth. esters example in shield tunneling in the field Concentrate share < 20 % of mining HFA-S Mineral oil-free watery solutions of Hydrostatic drives . industrial and mining hydraulics -20 to 60 °C Water-free. industrial hydraulics (mostly carboxylic acid. water-containing hydraulic fluids HFA-E Oil-in-water emulsions. mineral oil / Power hydraulics of about 300 bar. fast bio-degradable hydraulic fluids HEPG Polyalkylene glycol Water-soluble Hydrostatic drives.working pressures chemicals < 160 bar Concentrate share < 20 % 5 to < 55 °C HFB Water-in-oil emulsion Share of mineral oil 60 % For example in British mining 5 to 60 °C HFC Watery polymeric solution Water share > 35 % Hydrostatic drives.07 Classification of flame-retardant hydraulic fluids and water-free. fast bio-degradable hydraulic fluids Code letter according to Composition 7th Luxemb. mobile hydraulics -20 to 70 °C HEES Synthetic esters Not water-soluble Hydrostatic drives. e. -20 to 150 °C water-free in hydrostatic systems often 10 to 70 °C HFD-U Synthetic fluids of other composition Hydrostatic drives.Basic principles of hydraulics 21 Bosch Rexroth AG I RE 00845/04. mobile and industrial hydraulics -35 to 90 °C HEPR Hydrostatic drives. hydrocarbons) mobile and industrial hydraulics Not water-soluble -35 to < 80 °C Source: Specialist magazine 0 + P . ship lock hydraulics -30 to < 90 °C HETG Triglycerides (vegetable oils) Not water-soluble Hydrostatic drives. report.g. polyesters) -35 to 90 °C water-free Code letter according to VDMA 24568 and ISO 15380 Composition Typical properties Field of application Operating temperatures (Notes) Water-free. Typical properties DIN 51 502 and DIN EN ISO 6743/4: April 2002 Field of application Operating temperatures (Notes) Flame-retardant. 000 * Max. permitted (lubrication problems) 7 IS 6 O IS O 5 4 3. It is the resistance that material particles put up to the force during mutual shifting.0 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 120 140 Temperature °C Reference temperature for ISO viscosity classes Viscosity/temperature diagram with application limits for hydraulic systems Viscosity Comparison of different viscosity classes Viscosity is the reference for internal friction of the fluid.Basic principles of hydraulics Bosch Rexroth AG I RE 00845/04. permitted * Permitted briefly for cold start (cavitation) 100 Recommended range for continuous operation 36 20 12 10 9 8 0 68 10 G VG V 46 2 O SO 2 G I 3 2 15 V IS VG VG VG O O IS IS Ideal operating point Reference point for all data * Min. 20 W 46 10 W 32 5W 22 49 36 25 16 (15) 10 9 .07 10.000 Viscosity mm2/s Viscosity/ temperature diagram 22 1. SAE classes ISO .VG (DIN 51519) SAE classes 30 100 68 68 20. 07 No hydraulic fluid can meet all requirements.Basic principles of hydraulics Additives 23 Bosch Rexroth AG I RE 00845/04. Thanks to additives. certain properties of the hydraulic fluid can be optimized to suit the requirements of specific applications. For example: • for improving: – corrosion protection – pressure resistance – resistance to aging – viscosity/temperature behavior • for reducing: – the pour-point – foaming – wear . hydraulic fluid does therefore not get into the environment. vibration in the system due to increased compressibility. Danger If leakage on the hydraulic product can lead to the contamination of water and soil.Basic principles of hydraulics 24 Bosch Rexroth AG I RE 00845/04. dispersed air can cause severe problems. dispersed air (visible). When hydraulic systems are used properly. changed actuating times of servo-valves • Pump noise • Damage to pumps. While dissolved air and minor surface foam hardly show any adverse effects. which are finely dispersed and can rise to the surface only very slowly. Especially hydraulic hoses and hose connections must be intensively observed and inspected. Pressure fluids may only be used. Care must be taken that power units are leak-free and maintenance/repairs are carried out in due time.07 Practical notes Effects of air in the oil Air can be present in hydraulic oils in the following forms: as dissolved air (invisible). . and as undissolved. Oil changes must be made properly and thoroughly. the following troubles can occur: • Uneven or jerky movements of hydraulic spools. the hydraulic product must be placed in a suitable oil drip tray. Since the oil contains very small air bubbles. lines and seals caused by cavitation • Accelerated aging of the oil • Micro-diesel effect. a form of thermal cracking due to high temperatures in compressed air bubbles Environmental aspects Hydraulic systems are closed systems. waste oil must be disposed of in accordance with all relevant legal stipulations. if the corresponding safety data sheet of the manufacturer is at hand and all precautions prescribed therein are observed. Safety aspects Hydraulic fluids based on mineral oil are water-endangering and inflammable. as surface foam (visible). is often contaminated to an impermissibly high level. The contamination ingression rate to be expected depends exclusively on the contamination of the surroundings and the design of systems and components. dust.Basic principles of hydraulics Filters 25 Bosch Rexroth AG I RE 00845/04. Particles smaller than 15 µm are particularly wear-promoting. The preservatives bind dirt and dust.g. with which the hydraulic fluid is to be filled. – Contamination during the production of components (com­pon­ent­ contamination) Due to the often highly complicated internal contours of housings and internal parts of components. which are in most of the cases caused by high operating temperatures. sand. solid particles may be produced. The contamination to be removed by means of filters enters the hydraulic system from the surroundings via the filling connection or past the seals. – Contamination during operation of the hydraulic systems (production contamination) Abrasion in components results in the formation of particles. water or preservatives. scales. Especially during commissioning of the system. Fresh pressure fluid. the latter cannot in every case be sufficiently cleaned. welding beads. Ty­pi­cal contaminants are: Chips. change the tribological properties of the hydraulic fluid. paint flakes. rubber parts from hoses. Components are often preserved for intermediate storage. fibres. Aging residues in hydraulic fluids. installation of fittings. This type of contamination is termed ex­ter­nal contamination or contamination that enters the system from outside. residues of pickling and flushing fluids. Moving parts in the hydraulic system such as pumps. Ty­pi­cal contaminants are: Seal material. spools and valves also generate particles (abrasion).07 Causes of contamination One of the preconditions for the trouble-free operation of a hydraulic system is filtration of the hydraulic fluid and the ambient air connected to the tank. When the hydraulic system is flushed. . This dirt also gets into the hydraulic fluid when the system is commissioned. This type of contamination is termed internal contamination. cutting and grinding dust. The majority of malfunctions in hydraulic systems are caused by strongly contaminated hydraulic fluids. – Contamination during the assembly of systems (assembly contamination) When individual parts are joined. the contaminants get into the hydraulic fluid. there is a risk that the individual components are damaged or destroyed by solid particles that were transported into the system already during assembly. e. 5 to 5 μm 5 μm Vane pump J1 from 0.Basic principles of hydraulics Critical tolerances for hydraulic components 26 Bosch Rexroth AG I RE 00845/04.5 to 8 μm J2 from 100 to 450 μm J3 from 20 to 80 μm .5 to 1 μm J3 from 20 to 40 μm J4 from 1 to 25 μm Valve J1 from 5 to 25 μm Servo-valve J1 from 0.07 Gear pump J1 from 0.5 to J2 from 0.5 to 5 μm J2 from 5 to 20 μm J3 from 30 to 40 μm Piston pump J1 from 5 to 40 μm J2 from 0. Basic principles of hydraulics Causes and sources of contamination 1 2 3 4 5 External contamination Installation + repair Fresh oil Abrasion in the pump Abrasion of seals 27 Bosch Rexroth AG I RE 00845/04.07 . Filters perform certain tasks depending on their location in the system.07 The task of filters is directly related to their arrangement in the system. Main flow filtration Control 1 8 7 10 3 6 2 5 4 1 Built-on return flow filter 2 Filling filter 3 Breather filter 4 Suction filter 5 Hydraulic pump 6 Cooler 7 Hydraulic pump 8 High-pressure filter 9 Off-line filter 10 Underpressure switch Off-line filtration 9 .Basic principles of hydraulics Arrangement of filters in the open circuit 28 Bosch Rexroth AG I RE 00845/04. When the filter element is taken out. . the strainer is pulled out as well. which entered the system or are produced in the system. Advantages – Low cost – Ease of maintenance – Can be fitted with clogging indicator – Provides fine filtration – No pump cavitation Disadvantages – A by-pass valve is required – Lets dirt particles through the open by-pass valve in the case of pressure peaks and cold start conditions The filter shown below is mounted to the tank cover using a mounting flange.07 Return flow fil­ter These filters are located at the end of the return flow line and are designed mostly as filters for tank mounting. This means that the hydraulic fluid coming from the system is filtered before being fed back to the tank. An important feature is that a strainer encloses the filter element. the major part of dirt particles.Basic principles of hydraulics Filter types 29 Bosch Rexroth AG I RE 00845/04. The maximum flow must be taken into account for the selection of the filter size. thus preventing dirt already settled from flowing into the hydraulic tank. A great advantage of this filter design is good accessibility and consequently maintenance-friendliness. The filters are generally provided with a connection for a clogging indicator. Thus. The housing with the filter connection protrudes directly into the tank. The filter element can be quickly and easily taken out by removing the cover. are filtered out of the hydraulic fluid. This type of filter must be provided with a filter element that withstands also higher pressure differential loads without any damage. The fil­ter basically consists of a filter head with a screw-in filter housing and a filter element. Pressure filters should generally be fitted with a clogging indicator. only pressure filters without by-pass valve should be used. – Downtime costs of a system are extraordinarily high. these filters must be installed as closely as possible to the components to be protected. For this reason. Advantages – Can be installed directly upstream of sensitive components – No pump cavitation Disadvantages – Element must be provided for a high differential pressure . The stan­dar­d variant is designed without by-pass valve and without pressure unloading screw. – Com­po­nen­ts are particularly expensive (e.g.07 In-line filter (pressure filter) This filter type ensures that the function of downstream hydraulic components is maintained. Upstream of particularly critical components. large cy­lin­ders.Basic principles of hydraulics 30 Bosch Rexroth AG I RE 00845/04. ser­vo-valves. A connection for a clogging indicator is generally provided. hydraulic motors) and of extreme importance for the safety of a machine. system pressure. servo-valves or high-response valves) or decisive for the operation of a system.g. The filter housings must withstand the max. The following aspects are decisive for the use of pressure filters: – Com­po­nen­ts are particularly susceptible to dirt (e. A significant part of contaminants gets into hydraulic systems through unsuitable venting equipment. The air filters are available with different filtration ratings so that CETOP standard RP 70 can be complied with. which prescribes the same filtration rating for system filters and air filters. Depending on the required cleanliness class. However.07 Filler and breather filter Symbol for filler and breather filter without (on the left-hand side) and with by-pass valve (on the right-hand side) Filler and breather filter with and without filling filter Filler and breather filter with filling strainer In the past minor importance had been attached to these filters in hydraulic systems. Filler and breather filters basically consist of an air filter (1) for filtering the air flowing into the tank and a filling strainer (3) for retaining coarse particles when the system is filled with fluid. The requirements for this filter type are laid down in DIN 24557. breather filters are equipped with replaceable elements of different filtration ratings. Design measures such as pressurization of oil tanks are often uneconomical when compared with the highly efficient breather filters offered on the market today. according to latest findings. they are one of the most important elements for the filtration of hydraulic fluids in hydraulic systems. . The filters should be fitted with a connection for clogging indicators (2).Basic principles of hydraulics 31 Bosch Rexroth AG I RE 00845/04. The particles to be removed are also retained in the deeper layers of the filter. which are made of – impregnated cel­lu­lo­se­ materials (or­ga­ni­c fil­ter­ ma­te­ri­al). the flow resistance increases so that the filter element has to be replaced. – porous. For these filters. As more and more particles are retained by the filter. a) Surface filtration With surface filters. filter media are used. However. various filter media or a combination of filter media are used. sintered metal. . Particles that get into the filter medium due to their small diameter can pass through the filter without any hindrance. The filter cake built up on the surface can result in a reduction in the filtration rating. For surface filtration. – glass fiber material (in­or­ga­ni­c fil­ter­ ma­te­ri­al). the filter resistance increases as the surface is clogged.Basic principles of hydraulics Filtration media 32 Bosch Rexroth AG I RE 00845/04. b) Deep filtration The fluid to be filtered penetrates the filter structure. metal edges or Dutch weave are used. the particles are separated directly at the surface of the filter media. – sintered metal meshpacks.07 For the filtration methods described. diaphragm filters of filter materials made of wire mesh. Typical: – Blocking of nozzles – Jamming or seizing of spools – Material breakouts due to effect of large forces – Total failure due to severe abrasion Fine filtration Effective separation of finest. which can cause a sudden failure on the component to be protected.Basic principles of hydraulics Particle size and filtration rating 33 Finest particle contamination Finest particles (3 to 5 µm) cause an impairment of function and reduction in the performance due to: – the erosive effect of finest particles (often erosion on control lands) – fine sedimentation in narrow gaps (through edge filtration effect . The consequences are: – Increase in clearance due to abrasion (increased internal leakage) – Temporary failure (brief seizing effect on sliding spool valves or leakage on valve seats) Coarse particle contamination Coarse particles > 20 µm often cause a sudden total failure due to clogging and blocking effects or direct destruction.risk of clogging) – Changes of the operating medium (oil aging) as a result of chemical reactions on the particle surface Finest filtration Bosch Rexroth AG I RE 00845/04.07 Fine particle contamination Fine particles (5 to 20 µm) cause cratering mainly in narrow fits. Coarse filters protect the system against coarse particle contamination They reduce the risk of a sudden failure or total loss.Partial separation of fine dispersed particles particle contamination and (b3 to 5 → 100) complete separation of coarse-grain contamination High differential pressure(b5 to 20 → 100) stable finest filters safeguard the function Fine filters reliably control the acceptable degree of – They minimize the formacontamination of the system tion and further development of erosion – They protect components optimally against contami– They prevent clogging of nation narrow gaps – They reduce cratering – They provide protection against aging of oil – They prevent sudden failures of components – They prevent system malfunction Coarse filtration Separation of mainly coarse particles (bX → 100) X = µm particle size. . 100 > 100 00 125 22 4 1 0 0 250 44 8 2 0 1 500 89 16 3 1 2 1000 178 32 6 1 3 2000 356 63 11 2 4 4000 712 126 22 4 5 8000 1425 253 45 8 6 16000 2850 506 90 16 7 32000 5700 1012 180 32 8 64000 11400 2025 360 64 9 128000 22800 4050 720 128 10 256000 45600 8100 1440 256 11 512000 91200 16200 2880 512 12 1024000 182400 32400 5760 1024 Contamination classes to NAS 1638 Maximum number of dirt particles in 100 ml hydraulic fluid . Classification according to NAS 1638 14 cleanliness classes are available for the classification of the hydraulic fluid.15 15 .Basic principles of hydraulics Classification systems for the degree of contamination of the hydraulic fluid 34 Bosch Rexroth AG I RE 00845/04. Contamination class Particle size in µm 5 .07 The solid particle content in the hydraulic fluid is determined with the help of classification systems (standardized cleanliness classes).50 50 . The most common standards today are NAS 1638 (National Aerospace Standard) and DIN ISO 4406.25 25 . a certain number of particles (in 100 ml) is specified for each of the 5 sizes. For each class. Basic principles of hydraulics Classification according to ISO DIS 4406 Assignment of scale numbers 35 Bosch Rexroth AG I RE 00845/04.08 0.16 4 0.02 1 0.04 0.04 2 0.32 0.64 1.5 8 0.07 Number of particles per milliliter more than Scale number up to and including 2500000 > 28 1300000 2500000 28 640000 1300000 27 320000 640000 26 160000 320000 25 80000 160000 24 40000 80000 23 20000 40000 22 10000 20000 21 5000 10000 20 2500 5000 19 1300 2500 18 640 1300 17 320 640 16 160 320 15 80 160 14 40 80 13 20 40 12 10 20 11 5 10 10 2.01 0 .00 0.3 2.08 3 0.02 0.5 5 9 1.3 7 0.64 6 0.16 0.32 5 0.01 0. A pressure peak suppression and cold start suppression are additionally integrated. until finally the red indictor button pops out. the greater becomes the repulsive force between the magnets.Basic principles of hydraulics Filter clogging indicators 36 Bosch Rexroth AG I RE 00845/04. a unipolar magnet is mounted in the indicator head. maintenance intervals become foreseeable. a switching contact picks up. the differential pressure building up as a result of contamination of the element is converted contact-free into an analog electrical output signal with the help of a sensor. each change in pressure is recorded as change in travel by means of metering pistons or diaphragms. With the electrical variant.07 Inside the clogging indicators. The closer the poles come to each other. For a permanent indication of the element contamination electronic clogging indicators were developed. Differential pressure clogging indicators Backpressure clogging indicators . A piston with attached magnet is moved against the force of a spring inside the clogging indicator. On visual clogging indicators. Through the use of these indicators. With these fully electronic clogging indicators. for example. The hydraulic system may only be operated when in technically perfect condition. corrective maintenance) of the hydraulic system. safety regulations. When competitors' products are used. storage and maintenance (inspection.Safety notes  Bosch Rexroth AG I RE 00845/04. The use for the intended purpose. and it must be ensured that the components and systems comply with currently valid. performance data and operating conditions must not be changed. commissioning is prohibited until it was established that the electrohydraulic components and systems to be used meet the stipulations of all relevant EU Directives. Hydraulic oil based on mineral oil is water-endangering and inflammable. regulations for the prevention of accidents. If protective equipment must be bridged to allow servicing work to be carried out. Only when the operating instructions are strictly observed can accidents and damage to property be avoided and the trouble-free operation of the hydraulic system be ensured. Protective equipment / components must not be rendered inoperable. which ensure the proper use of the hydraulic system in accordance with its intended purpose. and include information and notes on transport. Warning For this reason. which prescribe the behavior during operation in order to prevent accidents and health damage and must be prepared by the operator/employer on the basis of.in this case mounting of electrohydraulic components on the training stand -. observing the operating instructions helps to: • reduce downtimes and repair costs • prolong the service life of the hydraulic system. The trainer must make the required documents available to the trainee. relevant EU Directives.g. The operating instructions are intended for information purposes and for the prevention of risks when hydraulic components are being installed in a system . the safety notes of the relevant manufacturer are applicable. It may only be used when the corresponding safety data sheet is available and all precautions prescribed therein were taken. Moreover. precautions must be taken to ensure that no dangerous situation can arise. valves or other control components. e.07 Fundamental safety notes In order that potential risks for plant and machinery can be recognized. by bridging limit switches. servicing. general safety notes Observe Warning • danger signs and safety notes on the machine • instructions. Fundamental. . product documentation and operating instructions must be observed. • operating instructions. The higher-order machine operating instructions must be observed. 07 Adjustment features on components may exclusively be operated or changes to programmable control systems made by authorized personnel within the framework of the intended use of the hydraulic system.Safety notes  Bosch Rexroth AG I RE 00845/04. • immediately inform the responsible specialist personnel. Uncontrolled access by external persons to the direct operating area of the hydraulic system is prohibited (even in case that the hydraulic system is at rest). In the case of an emergency. . fault or other irregularities: • hydraulic systems must be switched off and the main circuit breaker be secured against restarting. • the danger zone must be fenced off in order that nobody can enter the danger zone unknowingly or in an uncontrolled manner. Note: These are the fundamental safety regulations that must be observed for every project task. • equipment for fluid care such as filters. • feed carriages for tool transport. the hydraulic component such as a hydraulic cylinder or a hydraulic motor. • lifting gear for the horizontal transport of loads. • fluid flow consumers/hydraulic cylinders and motors. 01 . • punching equipment for punching perforated metal sheets. In the project order. • conveyor belts for transporting loads.07 Project 01: Hydraulic power unit Project/trainer information Hydraulics as technology can be assigned to drive technology. temperature and pressure. hydraulic components are grouped to form a compact assembly. This task is assumed by a transmission . The drive power is made available by an electric motor or combustion engine. coolers and heaters. the trainee sets up the required components on the basis of the given requirements. combined in a hydraulic power unit (without consumers). The basic components of a hydraulic system are: • Fluid flow generator/pump.in this case. open and closed-loop control devices and accessories. The power is transmitted by the hydraulic fluid. In this project task. • rotary drives for relocating workpieces. and • pressing equipment for workpiece pressing. he or she is to understand the following: • A hydraulic system consists of a fluid flow generator and a fluid flow consumer (actuator). A simple hydraulic power unit consists of: • Hydraulic pump with drive motor. The valves such as directional. This is equally valid for the engine of a passenger car as for the drive of the projects described in this project manual such as the drive of: • feed equipment for the vertical transport of workpieces. • open and closed-loop control equipment/valves. • accessories. pressure and flow control valves are in most of the cases installed separately into a machine. if required. • rope winches for lifting loads. to form a compact assembly. The task of drive engineering is to provide a drive for a machine or system that ensures optimum performance of the technological function. The output torque of the motor or engine is converted by a convertor into a rotary or linear movement as required by the machine. In the following Project 01 you can impart knowledge of the general structure of a hydraulic power unit.Project 01: Hydraulic power unit  Bosch Rexroth AG I RE 00845/04. • reservoir for storing the fluid. • valves for pressure relief functions and. • instruments for monitoring the fluid level. The components of a hydraulic system listed above can be designed as individual components or. • hydraulic accumulators as energy accumulators. • In a hydraulic power unit. • The size of the power unit. A hydraulic accumulator is not provided. variable vane pump with a displacement of qV = 20 l/min. • hydraulic filter with visual. the trainee is to set up a power unit on the basis of the conditions listed below and draw a sketch of a schematic diagram: • Hydraulic pump in the form of a pilot operated. • level monitor and • drain valve for changing the hydraulic fluid.g.5 times qV). mechanical clogging indicator. • electric motor for a maximum system pressure of p = 80 bar. • carrier components. • filler and breather filter. chapter 17 • The Hydraulic Trainer Volume 3/Bosch Rexroth AG Planning and design of hydraulic systems • Technical data sheet RE 51098 Modular standard power units • Technical data sheet RE 10515 Variable vane pump. • reservoir according to the displacement (3 . the capacity of the reservoir. In this project task. pilot operated 01 . Notes on the detailed technical information about hydraulic power units: • The Hydraulic Trainer Volume 1/Bosch Rexroth AG Basic principles and components. e. depends on the given conditions and customer requirements.07 • The required drive elements and the accessories such as control and monitoring devices as well as maintenance equipment can be mounted on top or to the hydraulic fluid reservoir.Project 01: Hydraulic power unit  Bosch Rexroth AG I RE 00845/04. 1 Practical example: Hydraulic power unit with hydraulic pump/el. 01. Fig. In the list of the hydraulic power unit components he requests the provision of short information about the selected components.Project 01: Hydraulic power unit  Bosch Rexroth AG I RE 00845/04. including a schematic diagram of the hydraulic system and a parts list. The customer wishes to get information about the structure of a hydraulic power unit with pilot operated vane pump. a hydraulic power unit with a variable displacement pump powered by an electric motor and associated accessories is to be used.07 01 Project definition In a hydraulic system for driving lifting equipment for heavy loads. motor and accessories Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet for a standard power unit with pilot operated vane pump (technical qualification) • Handling of hydraulic components in line with functional needs . • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? . among others. through the selection of power unit construction parts from a technical data sheet (RE 91098 / modular standard power units).07 01 Project steps Notes • Informing: Accepting and understanding the order. among others. • Planning: Planning and organizing the execution of the customer order. • Deciding: Hydraulic design and dimensioning of the power unit. through discussions with the customer. • Executing:: Preparation of a schematic circuit diagram and selection of the required drive elements and accessories with short description.Project 01: Hydraulic power unit  Bosch Rexroth AG I RE 00845/04. 01.2 Hydraulic schematic diagram: Drive power unit Item 5.0 Item 7.0 Item 1.0 Item 2.0 Item 3.0 Item 4.0 Fig.0 Item 9.0 Measuring glass Item 6.07 01 Hydraulic schematic diagram Item 10.0 Item 8.Project 01: Hydraulic power unit  Bosch Rexroth AG I RE 00845/04.0 . 5. pilot operated 3.0 1 Tank breather filter 9.1 Parts list for hydraulic circuit diagram Fig. closed at rest position S6-1X/. flow enabled in only one direction.0 1 Check valve with spring....0 1 Shut-off valve.2 Notes for the trainer: Items 9.07 01 Component selection with parts list Item Qty Component designation Type designation 1. ..0 listed in the parts list are accessory components for a training system and are not part of a hydraulic power unit in real industrial applications.0 1 Level control FSK 4.0 1 Measuring glass Symbol 100 L/steel PV7-1X/16-30.. Table 01.0 1 Variable displacement pump.0 and 10.Project 01: Hydraulic power unit  Bosch Rexroth AG I RE 00845/04.0 1 Filter with by-pass valve and pressure measuring device RF 060.0 1 Connection block with 1/4" coupler plug 10. 8. operated by turning 6. 01.0 1 Electric motor 4 KW/1450 rev/ min. 7.0 1 Reservoir with cover 2.. Check on the system pressure gauge that the system is depressurized.07 01 Safety notes To ensure the operability of plant and machinery. Before starting work on the training stand.Project 01: Hydraulic power unit  Bosch Rexroth AG I RE 00845/04. Relevant sources of regulations are given in the introduction of the present manual. and consequently to allow the recognition of potential risks. safety regulations must be observed before and during the execution of the order. that is. that the system is switched off. Notes . Warning Caution If work on electrohydraulic components is carried out improperly. make sure that electrical ON/OFF switches on the hydraulic power unit are pressed in. This can cause injury when the system is opened. Hydraulic systems can store pressure energy at rest. risks of injury and a safety risk can arise during operation of the system. including danger to life. 01. stop Force pA 10 F = F = force in N p = pressure in bar A = area in mm2 Velocity v= s t m v = velocity in s s = travel in m t = time in s Displacement/flow Vg  n  ηvol qV = 1000 qV = flow in l min cm3 rev n = Speed of the pump shaft in rev min Vg = geometric displacement in η = volumetric efficiency in % Pressure control valve Force / pressure limitation Motor power PM = PM p qV ηtotal. For this. 01.07 01 Execution of the order Dimensioning of a hydraulic power unit requires fundamental knowledge of hydraulic control technology. direction.3 Physical basic principles with formulas p  qV 600  ηtotal .3). In the project order. formulas from physical basic principles can be applied (see Fig.g. cylinder Annulus area AA Directional valve Start.Project 01: Hydraulic power unit  Bosch Rexroth AG I RE 00845/04. Piston area AP Flow control valve Change in velocity Force F Force = pressure • area v Pressure differential ∆p Energy converter e. The listing on the next page shows influencing factors that have to be taken into account when rating a hydraulic power unit.P = = = = power in kW pressure in bar l flow in min overall efficiency in % . only simple rules for the rating of power units can be applied. This also includes knowledge of the design of hydraulic systems inclusive of the drive power unit. fixed displacement pump Fig. Any power losses are not considered.P Energy converter e.g. climate • Pipe length to the consumer • Place of installation: integrated . NAS class 9 and a minimum retention rate of ß10 ≥ 100.maintenance Factors that have an influence on the rating of a return flow filter • Field of application. • A reliable calculation of cleanliness is impossible. return line filter = 0. water) – Heating • Noise .a MUST in modern hydraulic systems . environment • Susceptibility of components (the component with the most stringent requirement determines the filter rating for the entire system!) • The required cleanliness class and filter rating must be adhered to. State of art with regard to minimum requirements is. Both must be specified by the component manufacturer.1 bar.transmitted by pipes and air ducts • Acoustic insulation – Hoses – Compensators – Anti-vibration mounts – Low flow velocity – Pump selection – Encapsulation – Hydraulic accumulator – Silencers etc.separate • Duty cycle • Expected drive power • Volume fluctuation • Ambient temperatures – Heat dissipated by the reservoir – Cooling (air. because the ingress of dirt in relation to the ß value cannot be determined.visual and/or electrical • The tank breather filter must have the same filter rating as the fluid filters. ISO 4406 (c) class 20/18/15. not provided for pressure filters • Clogging indicator . 01 . viscosity and operating temperature of the fluid • Operating pressure • The flow rate determines the selection of the filter size • Permissible Dp across the clean element (Bosch Rexroth selection series: Rated Dp for a pressure filter .Project 01: Hydraulic power unit  Bosch Rexroth AG I RE 00845/04. surroundings . • Assembly .determined by the filter series.disassembly .4 bar) • By-pass valve . for example. • Arrangement of filters • Type.07 Factors that have an influence on the rating of a power unit • Environment. For the selection.5 kW. Electric motor: For rating the electric motor. When selecting the return flow filter. The provision of a drain valve is always recommended for changing the hydraulic fluid. required accessories for a hydraulic fluid reservoir are a return flow filter. the speed of the drive/electric motor must be known. 5. Accessories: In this project task. Calculation formula for the selection of the hydraulic motor: P= p • qV 600 in kW p in bar qV in l/min Also here. the next larger size is usually selected.. The topic of cooling is not dealt with in this simple engineering task. pump mounting bracket and damping elements will not be considered here and are not part of the order execution.500 rev/min. are employed. Hydraulic fluid reservoir: Hydraulic fluid reservoirs are selected on the basis of practical experience such as: Reservoir size = displacement of the hydraulic pump • 5 Whenever possible. Since manufacturers usually indicate only the sizes in technical data sheets (how much is displaced during one revolution of the pump?). a filler/breather filter and a level control device. the actual flow required for operating a single-rod cylinder must in any case be taken into account. i.e. The factors that have an influence on the selection of a return flow filter are listed on the previous page. the next larger frame size of the manufacturer's electric motor is selected.000 Because no manufacturer will be able to offer a hydraulic pump with exactly the requested power. i. 1. In industrial applications. etc. 4 kW.Project 01: Hydraulic power unit 10 Bosch Rexroth AG I RE 00845/04.e. how much oil returns from the hydraulic cylinder to the filter (see Project 04). For converting the displacement into power per unit of displacement the following formula can be applied: qV = Vg  n in l/min 1. please refer to technical data sheets of the manufacturers. motors of approx.g. which volume is the pump to provide within which time. 01 . 7.07 Hydraulic pump: The following must be known for rating the hydraulic pump: qV = ? l/min. e. the possible maximum system pressure must be known apart from the displacement of the hydraulic pump in l/min.5 kW. standard reservoirs of standardized sizes should be used. Typical frame sizes are. 3 kW. The selection of the required carrier components such as coupling. valves and accessories. this order execution does not involve any practical work on the training system. A component arrangement drawing and a general layout of the training system are therefore not provided. General note: In contrast to the following project tasks. 01 . see technical data sheet RE 50081.Project 01: Hydraulic power unit 11 Bosch Rexroth AG I RE 00845/04. For the simplified rating of a return flow filter. Evaluating the work results in relation to the customer requirement • A hydraulic system consists of a fluid flow generator and a fluid flow consumer. • The required drive elements and reservoir accessories such as control and monitoring and maintenance devices can be mounted to or on top of the reservoir. Detailed notes on the engineering and design of hydraulic systems can be found in The Hydraulic Trainer Volume 3/Bosch Rexroth AG.07 As additional aid for rating a hydraulic power unit we recommend the use of a hydraulic slide rule. • The size and design of the hydraulic power unit depends on the given conditions and the requirements of the customer. • A hydraulic power unit accommodates the hydraulic components to form a compact unit. Project 01: Hydraulic power unit Notes 12 Bosch Rexroth AG I RE 00845/04.07 01 . complementing the circuit diagram and parts list. first name Hydraulic power unit …………………………………………………………………………………………………………… Project handler Customer requirement: …………………………………………………………………………………………………………… – Hydraulic circuit diagram …………………………………………………………………………………………………………… – Parts list …………………………………………………………………………………………………………… – Information about components Project designation Informing from the project definition.Project 01: Hydraulic power unit Project schedule: Project 01 13 Bosch Rexroth AG I RE 00845/04. Planning steps Planning of the project objective and the proceeding. …………………………………………………………………………………………………………… (Overleaf) 01 . …………………………………………………………………………………………………………… – System rating/calculation …………………………………………………………………………………………………………… Understand the circuit diagram …………………………………………………………………………………………………………… Identifiy components …………………………………………………………………………………………………………… Supplement parts lists …………………………………………………………………………………………………………… Rate components …………………………………………………………………………………………………………… Evaluate the result …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… Sources of information DIN ISO 1219 …………………………………………………………………………………………………………… The Hydraulic Trainer Volume 1 …………………………………………………………………………………………………………… Project manager …………………………………………………………………………………………………………… Data sheets …………………………………………………………………………………………………………… Internet …………………………………………………………………………………………………………… Hydraulics supplier …………………………………………………………………………………………………………… Select components from data sheets …………………………………………………………………………………………………………… Make calculations …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… Decision-making Deciding on and selecting components. John ……………………………………………………………………………………… Last name.07 Q. Public. Project 01: Hydraulic power unit 14 Bosch Rexroth AG I RE 00845/04.07 01 Summarize the information obtained …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… Execution of the order …………………………………………………………………………………………………………… Execution Set-up of the electrohydraulic control and acquisition of required data. …………………………………………………………………………………………………………… Special points? Pump data sheet RE 10515 is very complex …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… Comparison of summary with customer requirements …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… Quality check …………………………………………………………………………………………………………… Checking Are all customer requirements met? …………………………………………………………………………………………………………… Evaluating Optimize project steps (If required, add supplementary sheet) Assign individual project steps to team members → faster results ……………………………………………………………………………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………………………………………………………………………… Project 01 …………………………………………………………………………………………………………………………………………………………… Note of completion by confirmation of the project manager/place, date, signature Project 02: Hydraulic variable displacement pump  Bosch Rexroth AG I RE 00845/04.07 Project 02: Hydraulic pump/characteristic curve of variable displacement pump Project/trainer information In a hydraulic system, fluid flow generators/hydraulic pumps convert the mechanical energy of a drive motor (torque, speed) into hydraulic power (flow, pressure). The hydraulic pump usually aspires the hydraulic fluid from a storage tank (suction side) and displaces it to the pump outlet (pressure side). In terms of construction, hydraulic pumps can be differentiated as follows: Gear, internal gear, screw, vane, radial piston and axial piston pumps. Hydraulic pumps are displacer pumps, the displacement of which can be either fixed or variable. Hydraulic pumps that feature an adjustable displacement are called variable displacement pumps. The displacement/flow is adjusted by means of mechanical or electronic control systems. In the following Project 02 you can impart knowledge of the interrelationship between the hydraulic variable displacement pump, the displacement and pressure build-up through resistances in the hydraulic system. In the project order, the trainee is made familiar with the characteristic curves of a pilot operated variable displacement vane pump and the direct relationship between the displacement and the system pressure. This project task is to help the trainee to understand the following: • With hydraulic variable displacement pumps, the flow is almost reduced to zero when the system pressure has been reached. • Due to the design of a variable displacement pump, internal leakage oil occurs, which is refed to the reservoir through an external leakage oil line. • The leakage oil flow increases as the resistance rises, which opposes the displacement in the pressure line of the pump • The drained leakage oil flow is the power loss of the hydraulic pump. With the help of the control set up on the training system, the trainee can recognize that when the system pressure increases as resistance at the pressure port of the hydraulic pump, the total displacement reduces. The resistance is realized by means of a hand lever valve, with the system pressure being steplessly variable via a pressure relief valve operated in parallel. Notes on the detailed technical information about hydraulic variable displacement pumps: • The Hydraulic Trainer Volume 1/Bosch Rexroth AG Basic principles and components, chapter 4 • Technical data sheet RE 10515 Variable vane pump, pilot operated 02 Project 02: Hydraulic variable displacement pump  Bosch Rexroth AG I RE 00845/04.07 Project definition In a hydraulic power unit, the hydraulic energy is to be provided by a variable, pilot operated vane pump. The power that can be generated by the hydraulic pump is to be measured in an experiment set-up. The customer wishes detailed information about the pros and cons of this vane pump, including a flow characteristic curve, from which the relationship between increasing system pressure and losses of the vane pump can be seen. Fig. 02.1 Practical example: Vane pump/function elements Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet for a pilot operated vane pump (technical qualification) • Handling of hydraulic components in line with functional needs 02 Project 02: Hydraulic variable displacement pump  Bosch Rexroth AG I RE 00845/04.07 Project steps Notes • Informing: Accepting and understanding the order, among others, through discussions with the customer. • Planning: Planning and organizing the execution of the customer order; among others, through the selection of components from a technical data sheet (RE 10515 vane pump, pilot operated). • Deciding: Preparation of a circuit diagram sketch and selection of components. • Executing:: Working out the set-up of a hydraulic control on the training system, documenting the characteristic curve required by the customer and providing explanations with regard to the characteristic curves and power losses. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? 02 Project 02: Hydraulic variable displacement pump  Bosch Rexroth AG I RE 00845/04.07 Hydraulic circuit diagram 02 Item 1.1 Item 1.2 Item 0.1 Item 1.0 Power unit limit Fig. 02.2 Hydraulic circuit diagram: Test set-up Measuring glass Project 02: Hydraulic variable displacement pump  Bosch Rexroth AG I RE 00845/04.07 Component selection with parts list Item Qty Component designation Type designation 1.0 1 Direct operated pressure relief valve; the cracking pressure can be adjusted by means of a spring DD 1.1 1.1 1 Throttle valve, adjustable DF 1.2 1.2 1 Shut-off valve, operated by turning DZ 2.1 0.1 1 Pressure gauge with hose and quick-release coupling, without check valve DZ 1.4 1 Hydraulic hose with minimess connection DZ 25.1 Hose with quick-release coupling, with check valve 1 Symbol VSK 1 Stopwatch Table 02.1 Parts list for hydraulic circuit diagram Fig. 02.2 Notes for the trainer: The pilot operated, variable vane pump is not included as individual component in parts list table 02.1. It is an integral part of the hydraulic power unit from Project 01. 02 Project 02: Hydraulic variable displacement pump  Bosch Rexroth AG I RE 00845/04.07 Component arrangement Connection block Measuring glass 02 D Note: In the case of connection elements marked with “D”, the components can be connected directly with each other. Fig. 02.3 Recommended component arrangement with component designation for parts list table 02.1 and hydraulic circuit diagram Fig. 02.2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. Also the grid layout is Rexroth-specific and adapated for use on the training system. Notes Project 02: Hydraulic variable displacement pump  Bosch Rexroth AG I RE 00845/04.07 Safety notes To ensure the operability of plant and machinery, and consequently to allow the recognition of potential risks, safety regulations must be observed before and during the execution of the order. Relevant sources of regulations are given in the introduction of the present manual. Warning Caution If work on electrohydraulic components is carried out improperly, risks of injury and a safety risk can arise operation of the system, including danger to life. Before starting work on the training stand, make sure that electrical ON/OFF switches on the hydraulic power unit are pressed in, that is, that the system is switched off. Check on the system pressure gauge that the system is depressurized. Hydraulic systems can store pressure energy at rest. This can cause injury when the system is opened. Execution of the order Set-up of the control as described in the following: 1. Mount the components required according to Table 02.1 on the training system in a clearly arranged manner according the prepared circuit diagram. Connect the hydraulic control according to hydraulic circuit diagram Fig. 02.2 by means of hoses. For connections, to which pressure gauges with minimess hose DZ 1.4 are to be connected, use hydraulic hoses DZ25. Hand-tighten the pressure gauge measuring lines hand tight at the relevant minimess connection of the hydraulic hose. The proper and tight fit of hose connections of components can be easily checked by slightly turning the hoses. Warning Caution Make sure that pipes or hoses are connected to all connections - in this case also to minimess lines, or that the connections are plugged by means of plug screws or protective caps. Leakage oil may drip through open connections and cause a slipping risk. Before commissioning the hydraulic control, i.e. before switching the hydraulic pump on, check, whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open. An electrical control is not required for this experiment set-up. Completely close throttle valve item 1.1. To this end, turn the adjustment element clockwise to the mechanical limit stop. Close shut-off valve item 1.2. 2. Switch the hydraulic pump on and check and the set up control for any leakage. 3. Adjust the system pressure on pressure relief valve item 1.0 to 50 bar plus one turn. 4. Check the set pressure on the variable displacement pump of the drive power unit (zero stroke pressure 50 bar). 02 Project 02: Hydraulic variable displacement pump  Bosch Rexroth AG I RE 00845/04.07 Flow measurement 5. Open shut-off valve item 1.2. 6. Open throttle valve item 1.1 until a pressure of 15 bar is present at measuring point M1. 7. Flow measurement by means of the measuring glass; to this end, close shut-off valve item 1.2, close the measuring glass, open shut-off valve item 1.2 for 10 s. Record the filling quantity and enter the measured value in Table 02.2. 8. Take flow measurements as described in points 6. to 7. at pressure values of 30 bar, 40 bar, 45 bar and 50 bar and enter the recorded measured values in Table 02.2. Caution After completion of practical work, switch the hydraulic pump on the training system off! Turn pressure relief valve item 1.0 back to minimum pressure. Open throttle valve item 1.1 completely. No pressure gauge may indicate a pressure! 9. Calculate the measured oil flow/time and enter it as flow in qV = l/min in Table 02.2. Enter the individual values as points in Diagram 02.3 and connect the individual points with a line to create a curve. The resulting curve is the typical characteristic curve of the pilot operated, variable vane pump. Measured values Pressure p bar 15 30 40 45 50 Time t s 10 10 10 10 10 Volume V l 1.32 1.25 1.20 1.10 0 Flow qV l/min 7.92 7.50 7.20 6.60 0 Table 02.2 Evaluation of the measured oil volumes The values were measured at an oil temperature of approx. 20 °C. The values measured by trainees can deviate by 10 %. 02 Project 02: Hydraulic variable displacement pump  Bosch Rexroth AG I RE 00845/04.1 Characteristic curve of the hydraulic pump Evaluating the work result with regard to the customer requirement • On hydraulic variable displacement pumps. the displacement is reduced to almost 0 l/min when the maximum pressure set on the hydraulic pump is reached. .07 Flow qV in l/min 02 Operating pressure p in bar Diagram 02. • The amount of leakage oil in the variable displacement pump increases as the resistance/ pressure at the pressure port of the hydraulic pump rises. • The amount of leakage oil corresponds to the power loss of the pump. • Internal leakage oil in the variable displacement pump must be fed back to the reservoir via an external leakage line. Project 02: Hydraulic variable displacement pump 10 Bosch Rexroth AG I RE 00845/04.07 Notes 02 . the trainee is to work out the physical basic principles of pressure intensification with single-rod cylinders. When throttling.07 Project 03: Single-rod cylinder/pressure intensification Project/trainer information If in a hydraulic system the hydraulic force. lowering. In the project order. Lifting. the possible maximum cylinder force F in kN depends on the possible maximum system pressure p and the effective piston area A of the hydraulic cylinder. i. Notes on detailed technical information about hydraulic cylinders: • The Hydraulic Trainer Volume 1/Bosch Rexroth AG Basic principles and components. On the basis of this project task. When the hydraulic pump is switched on. the piston velocity. he/she is to understand the following: • The hydraulic cylinder performs a straight movement and transmits the supplied piston pressure in the form of force. The hydraulic cylinder as output element forms the link between the hydraulic circuit and the working element/tool in a technological system. important physical laws must be taken into account. Flow control valves are used to change.e. a hydraulic cylinder is used. is to be transmitted to an actuator in the form of a linear (straight) movement. for example. A in cm m2 The piston velocity v in m/s of the hydraulic cylinder is determined by the pump flow supplied. Neglecting friction. • Forces and velocities can be kept constant over the entire stroke. Chapter 7 • Technical data sheet RE 17039 Hydraulic cylinders of tie rod design 03 . Retracting of the single-rod cylinder is accomplished with the help of a 4/2 directional valve. F = p • A in dN p in bar. locking and transporting loads are typical applications of hydraulic cylinders. reduce. Biased on the control set up on the training system the trainee is to learn that the use of a meterout throttle on the piston rod side involves a risk of pressure intensification. the piston extension velocity. single-rod and double-rod cylinders.e. i. The extension velocity can be varied by means of a throttle valve. the piston of the single-rod cylinder extends. which is converted into mechanical energy.Project 03: Single-rod cylinder / pressure intensification  Bosch Rexroth AG I RE 00845/04. In the following Project 03 knowledge can be imparted with regard to the use of single-rod cylinders as machine elements. • Double-acting hydraulic cylinders with different piston areas are pressure intensifiers. We distinguish hydraulic cylinders by their design principles: Plunger. • Due to adhesive friction in the hydraulic cylinder the pressure actually transmitted via the piston area or through the differences in areas is reduced. Retracting is to be achieved by means of a 4/2 directional valve. To this end. The customer installed a throttle valve on the piston rod side and. recognizes that the pressure upstream of the throttle becomes higher than the set system pressure. the extension velocity of the cylinder must be adjustable.07 Project definition A workpiece is to be shifted by a horizontally installed single-rod cylinder to the working range of a simple fixture when the hydraulic pump is switched on.1 Practical example: Hydraulic cylinder of tie rod design Project tasks • Independent understanding and execution of the task set through application of hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet of a hydraulic cylinder (specialist qualification) • Handling of hydraulic components in line with functional needs 03 . Fig.Project 03: Single-rod cylinder / pressure intensification  Bosch Rexroth AG I RE 00845/04. 03. Apart from the technical documentation he wishes to get an explanation of the pressure intensification of the single-rod cylinder. while adjusting the extension velocity. Working out and documenting the system parameters required by the customer and explanations with regard to pressure intensification on the basis of a calculation example. through the selection of hydraulic components from the data sheet collection (RE 17039 Hydraulic cylinders. tie rod design). among others. • Planning: Planning and organizing the execution of the customer order. through discussions with the customer. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? 03 . • Deciding: Preparation of a schematic diagram sketch and selection of components.Project 03: Single-rod cylinder / pressure intensification  Bosch Rexroth AG I RE 00845/04.07 Project steps Notes • Informing: Accepting and understanding the order. • Executing: Set-up of the hydraulic control on the training system. among others. 07 Hydraulic circuit diagram 03 Item 1.2 Power unit limit Fig.Project 03: Single-rod cylinder / pressure intensification  Bosch Rexroth AG I RE 00845/04.1 Item 0. 03.3 Item 1.0 Item 0.3 Item 1.1 Item 1.2 Hydraulic circuit diagram: Feeding cylinder Measuring glass .2 Item 0. 3 Wiring diagram re hydraulic circuit diagram Fig.Project 03: Single-rod cylinder / pressure intensification  Bosch Rexroth AG I RE 00845/04. 03. Fig. 03.2 .07 Electrical circuit diagram 03 Control 4/2 directional valve Retraction -Single-rod cylinderNote: The single-rod cylinder extends automatically when the hydraulic pump is switched on. 1 Parts list for hydraulic circuit diagram Fig.3 1. 03.1 1.1 0.4 3 Hose with quick release coupling with check valve DZ 25. spring return DW 3 E 1.2 1 Distributor plate with four ports DZ 4.1 3 Pressure gauge with hose and quick release coupling without check valve DZ 1.2 Type designation VSK 1 Symbol 03 .07 Component selection with parts list Item Qty 1.Project 03: Single-rod cylinder / pressure intensification  Bosch Rexroth AG I RE 00845/04.3 1 Throttle valve.2 1 Direct operated pressure relief valve. adjustable DF 1. the cracking pressure can be adjusted by means of a spring DD 1.0 1 Double-acting cylinder with single-sided piston rod ZY 1.0.1 .3 Component designation Hose Table 03.1 1 4/2 directional valve with solenoid actuation. 03. 03.Project 03: Single-rod cylinder / pressure intensification  Bosch Rexroth AG I RE 00845/04. Fig.2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. the components can be connected directly with each other.1 and hydraulic circuit diagram Fig. Also the grid arrangement is Rexroth-specific and adapted for use on the training system. Notes .4 Recommended component arrangement with component designations for parts list Table 03.07 Component arrangement Connection block Measuring glass 03 D Note: In the case of connection elements marked with “D”. 4. or that the connections are plugged by means of plug screws or protective caps.2 by means of hoses. It can cause injury when the system is opened. Warning Caution If work on electrohydraulic components is carried out improperly. 03.2 to 50 bar plus one turn. For connections. Hand-tighten the pressure gauge measuring lines at the relevant minimess connection of the hydraulic hose. and the piston of the hydraulic cylinder extends due to the pump flow supplied directly to the piston side. operate push-button S2 to prevent the piston of hydraulic cylinder Item 1. No pressure gauge may indicate a pressure. including danger to life. safety regulations must be observed before and during the execution of the order.e. correct to 50 bar).4 are to be connected. check. Switch the hydraulic pump on and inspect the set up control for leakage. Relevant sources of regulations are given in the introduction of the present manual. i. Leakage oil may drip through open connections and cause a slipping risk.0 from extending. Through operation of push-button S1 the control voltage of solenoid Y1 of the 4/2 directional valves Item 1. Set the system pressure on pressure relief valve Item 1. before switching the hydraulic pump on.1 drops. i.in this case also to minimess lines. Warning Caution Make sure that pipes or hoses are connected to all connections . check that the electrical ON/ OFF switch on the hydraulic power unit is pressed in. 03 .Project 03: Single-rod cylinder / pressure intensification  Bosch Rexroth AG I RE 00845/04. that the system is switched off.1 in a clearly arranged form on the training system according to the prepared circuit diagram. Execution of the order Set up the control as described below: 1. 2. whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open. to which pressure gauges with minimess line DZ 1. Hydraulic systems can store pressure energy when at rest. Before starting work on the training stand. The correct and proper fit of the component connections with hoses can be checked by slightly turning the hoses. 3.e. Check the pressure set on the variable displacement pump of the drive power unit (if required. use hydraulic hoses DZ 25. 5. Mount the components required according to Table 03.3. 03. risks of injury and a safety risk can arise during operation of the system. Before commissioning the hydraulic control. Connect the hydraulic control according to hydraulic circuit diagram Fig. and consequently to allow the recognition of potential risks. Wire the electrical control according to wiring diagram Fig. Use the system pressure gauges to check that the system is depressurized.07 Safety notes To ensure the operability of plant and machinery. 2 back to minimum pressure. Pressure gauge M3 indicates the value of pressure intensification.07 pR =  50 bar = 103.07 : 1 If the meter-out throttle is completely closed. turn in the adjustment element counter-clockwise to the limit stop. 20 °C.Project 03: Single-rod cylinder / pressure intensification  Bosch Rexroth AG I RE 00845/04..2. Switch the hydraulic pump off and wait until the system is depressurized.54 cm2 = 2. since the throttle valve is closed.25/18. The values measured by the trainees can deviate by 10 %. Close throttle valve Item 1. Additional task in conjunction with the customer requirement: Calculation of the pressure intensification on the basis of given hydraulic cylinder values.200 Bore: Piston rod diameter: 25 mm 18 mm Apiston = 4. Switch the hydraulic pump on.3. 7.2 Pressure intensification values measured The values were measured at an oil temperature of approx. Note the measured values and enter them in Table 03. because the counterforce on the piston rod side is greater than the force on the piston side. No pressure gauge may indicate a pressure! Measured values Hydraulic cylinder Measuring point M1 System pressure p in bar M2 piston side p in bar M3 piston rod side p in bar 48 48 82 Extending/ Y1 not operated Table 03.. Hydraulic cylinder of tie rod design: Type CD T3..5 bar 1.3 37 cm2 4.00 03 .54 cm2 Aannulus = 2.91 cm2 2. To this end. Caution After having completed practical work on the training system switch the hydraulic pump off! Turn pressure relief valve Item 1.07 6. The piston of the hydraulic cylinder cannot extend..91 cm2 Arod = 2. then: FK = FR pK  AK = pR  AR 2. 03 .Project 03: Single-rod cylinder / pressure intensification 10 Bosch Rexroth AG I RE 00845/04.07 Evaluating the work results with regard to the customer requirement • Hydraulic cylinders perform linear movements and transmit the piston pressure in the form of force. • Single-rod cylinders are pressure intensifiers. • Double-acting hydraulic cylinders with different areas are called single-rod cylinders. • Velocities can be kept constant over the entire stroke. the line system and power unit accessories such as filtration and cooling systems. On the basis of the control set up on the training system the trainees are to recognize that the cylinder piston retracts and extends at different velocities. In this project order. To prevent high flow velocities in the connected hoses and pipes. single-rod cylinders feature different piston velocities. the piston of the hydraulic cylinder retracts. Controlled by a 4/2 directional valve. the latter must be selected taking into account the given flow supplied by the hydraulic pump and the area ratio of the single-rod cylinder. the load force generated by the moved workpiece often has an influence on the piston velocity (see Project 09 . they are to understand the following: • The piston velocity of a double-acting cylinder . Here. Chapter 7 • Technical data sheet RE 17039 Hydraulic cylinders. in particular with reference to the piston velocities and flows. Notes on detailed technical information about hydraulic cylinders: • The Hydraulic Trainer Volume 1/Bosch Rexroth AG Basic principles and components. different flows occur during extending and retracting of the cylinder. Through this project task. When the hydraulic pump is switched on.07 Project 04: Single-rod cylinder/flow Project/trainer information If a hydraulic cylinder in a hydraulic system is not only to transmit the force. the piston of the single-rod cylinder extends. which have an influence on the selection of connection elements. double-acting hydraulic cylinders are used such as: single-rod and double-rod cylinders. Due to the different areas.Project 04: Single-rod cylinder/flow  Bosch Rexroth AG I RE 00845/04. AK AK AR AR =ϕ Area ratio of the single-rod cylinder 40 20 10 Values in l/min 20 e. qV = 20 l/min ϕ = 2 : 1 The following Project 04 is intended to impart knowledge of the use of single-rod cylinders as machine element. the trainees are to be made familiar the velocity behavior during the extension and retraction of the cylinder piston of single-rod cylinders. tie rod design 04 .10). • The different piston areas result in different flow velocities. but also work in the form of piston velocity. Due to the area ratio of the piston side to the piston rod side. • In the case of double-rod cylinders.g. the forces transmitted and the piston velocities are identical in both directions of action of the piston.single-rod cylinder . The extension and retraction velocity can be changed by means of a throttle valve on the piston rod side. even if the pump flow provided remains unchanged.depends on the cylinder size and the supplied flow. Apart from the technical documentation. 04. He also requests details about the filling volume of the hydraulic cylinder used. To this end. The return is to be accomplished with the help of a 4/2 directional valve. The customer observes that with an open throttle valve the piston velocities during extending and retracting of the cylinder are different. Fig.Project 04: Single-rod cylinder/flow  Bosch Rexroth AG I RE 00845/04.07 Project definition Like in Project 03 a workpiece is to be moved to the working range of a simple fixture by a horizontally installed single-rod cylinder when the hydraulic pump is switched on. the extension velocity of the cylinder must be adjustable. he wishes to obtain an explanation with regard to the different piston velocities of the single-rod cylinder.1 Practical example: Schematic illustration of flow velocities in the single-rod cylinder Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet of a hydraulic cylinder (specialist qualification) • Handling of hydraulic components in line with functional needs 04 . • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? 04 . through the selection of hydraulic components from the data sheet collection (RE 17039 Hydraulic cylinders of tie rod design). • Deciding: Preparation of a schematic diagram sketch and selection of components. among others. through discussions with the customer.Project 04: Single-rod cylinder/flow  Bosch Rexroth AG I RE 00845/04. Prepration and documentation of the information and explanations with regard to the single-rod cylinder as demanded by the customer.07 Project steps Notes • Informing: Accepting and understanding the order. • Planning: Planning and organizing the execution of the customer order. • Executing: Set-up of the hydraulic control on the training system. among others. 2 Item 0.1 Item 0.2 Hydraulic circuit diagram: Feed cylinder Measuring glass .2 Power unit limit Fig.07 Hydraulic circuit diagram Item 1.0 04 Item 0.Project 04: Single-rod cylinder/flow  Bosch Rexroth AG I RE 00845/04.3 Item 1. 04.3 Item 1.1 Item 1. 07 Electrical circuit diagram 04 Control 4/2 directional valve Retraction -Single-rod cylinderNote: The single-rod cylinder extends automatically when the hydraulic pump is switched on. 04. 04.2 .Project 04: Single-rod cylinder/flow  Bosch Rexroth AG I RE 00845/04.3 Wiring diagram re hydraulic circuit diagram Fig. Fig. 07 Component selection with parts list Item Qty Component designation Type designation 1. the cracking pressure can be adjusted by means of a spring DD 1.1 1 4/2 directional valve with solenoid actuation.2 1 Distributor plate with four ports DZ 4. adjustable DF 1. spring return DW 3 E 1.1 1. 04.1 Parts list for hydraulic circuit diagram Fig.3 Hose 1 Stopwatch 1 Flowmeter Table 04.0.3 1 Throttle valve.1 0.3 1.Project 04: Single-rod cylinder/flow  Bosch Rexroth AG I RE 00845/04.4 3 Hose with quick release coupling with check valve DZ 25.2 VSK 1 DZ 30 Symbol 04 .2 1 Direct operated pressure relief valve.1 .1 3 Pressure gauge with hose and quick release coupling without check valve DZ 1.0 1 Double-acting cylinder with singlesided piston rod ZY 1. Also the grid arrangement is Rexroth-specific and adapted for use on the training system.4 Recommended component arrangement with component designations for parts list Table 04. the components can be connected directly with each other.2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations.1 and hydraulic circuit diagram Fig. 04.07 Component arrangement ����� ������ ������ ������ 04 ������� Measuring glass ������� ����� � ����� ����� Note: The component arrangement shows the optional variant with electronic flow measurement ������ D � � � � ������ � ����� � Connection block ������ ������ � Note: In the case of connection elements marked with “D”. Notes .Project 04: Single-rod cylinder/flow  Bosch Rexroth AG I RE 00845/04. 04. ������ ������� Fig. operate push-button S2 to prevent the piston of hydraulic cylinder Item 1. Connect the hydraulic control according to hydraulic circuit diagram Fig. Switch the hydraulic pump on and inspect the set up control for leakage. The extension velocity of hydraulic cylinder piston Item 1.2 by means of hoses. 4. 6. Due to the operation of push-button S2 the control voltage of solenoid Y1 of the 4/2 directional valve Item 1. that the system is switched off. risks of injury and a safety risk can arise during operation of the system. to which pressure gauges with minimess line DZ 1. safety regulations must be observed before and during the execution of the order.e. Check the pressure set on the variable displacement pump of the drive power unit (if required.0 from extending.0 is to be adjusted to 5 s by means of throttle valve Item 1. Mount the components required according to Table 04. Hand-tighten the pressure gauge measuring lines at the relevant minimess connection of the hydraulic hose.1 in a clearly arranged form on the training system according to the prepared circuit diagram. Check on the system pressure gauge that the system is depressurized. Warning Caution If work on electrohydraulic components is carried out improperly.1 is not operated. No pressure gauge may indicate a pressure. use hydraulic hoses DZ 25.in this case also to minimess lines.1 drops and the piston of the hydraulic cylinders extends due to the pump flow fed directly to the piston side. It can cause injury when the system is opened.3. For connections. Leakage oil may drip through open connections and cause a slipping risk. Hydraulic systems can store pressure energy when at rest. 2. and consequently to allow the recognition of potential risks. including danger to life. 04. 04. Before starting work on the training system. Wire the electrical control according to wiring diagram Fig. 04 .Project 04: Single-rod cylinder/flow  Bosch Rexroth AG I RE 00845/04. The correct and proper fit of the component connections with hoses can be checked by slightly turning the hoses. correct to 52 bar). Relevant sources of regulations are given in the introduction of the present manual. check.4 are to be connected. whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open.07 Safety notes To ensure the operability of plant and machinery. Execution of the order Set up the control as described below: 1. check that the electrical ON/ OFF switch on the hydraulic power unit is pressed in. i.3 while directional valve Item 1. before switching the hydraulic pump on. or that the connections are plugged by means of plug screws or protective caps. i. 3. Before commissioning the hydraulic control.e.2 to 50 bar plus one turn. 5. Warning Caution Make sure that pipes or hoses are connected to all connections . Set the system pressure on pressure relief valve Item 1. 01 cm2 Aannulus = 2. The values measured by the trainees can deviate by 10 %.07 7.051 - Extended b 50 49 0 - - 0. M3 during extending.098 Retracting a 49 0 6 3.. Establish the time required for extending and retracting by means of a stopwatch and enter the values also in Table 04.2 0.2.073 - Retracted a 50 0 49 - - 0.91 cm2 Arod = 2.91 cm2 • 20 cm = 98. M2. Hydraulic cylinder of tie rod design Bore: 25 mm Piston rod diameter: 16 mm Piston stroke: Apiston = 4.0 cm3 = 0. Completely open throttle valves.2 cm3 = 0.. Measure the pressures at measuring points M1. Additional task in conjunction with the customer requirement: Calculation of the filling volume of the single-rod cylinder used for the execution of the order (enter calculated values in Table 04.2).200 A in cm2 s in mm V in l V = 4.098 l V = 2.90 cm2 • 20 cm = 58.Project 04: Single-rod cylinder/flow  Bosch Rexroth AG I RE 00845/04. if installed.058 Table 04. No pressure gauge may indicate a pressure! Measured values Hydraulic cylinder Piston position Position 4/2 directional valve M1 M2 M3 p in bar p in bar p in bar t in s v in m/s V in l Extending b 49 0 0 5 0. 20 °C.. Caution After having completed practical work on the training system switch the hydraulic pump off! Turn all pressure valves of the electrohydraulic control back to minimum pressure.058 l 04 .2. retracting and at the relevant end position of the cylinder and enter the values in Table 04..25/16.2 Values of velocity/flow measurement The values were measured at an oil temperature of approx.90 cm2 200 mm = 20 cm V = A • s Fill: Piston volume: Type: CD T3. the piston velocities are identical in both directions. • With double-rod cylinders with identical piston rods on both sides. 04 .07 Evaluating the work results with regard to the customer requirement • The extension and retraction velocity of a single-rod cylinder piston depends on the supplied hydraulic pump flow and the cylinder areas.Project 04: Single-rod cylinder/flow 10 Bosch Rexroth AG I RE 00845/04. Hydraulic motors convert hydraulic energy into mechanical energy. • The torque of hydraulic motors is determined by the differential pressure between the inlet and the outlet and by the swept volume.07 Project 05: Hydraulic motor Project/trainer information If the hydraulic force is to be transmitted via a rotary movement to an actuator in a hydraulic system. In principle. Notes on detailed technical information about hydraulic motors: • The Hydraulic Trainer Volume 1/Bosch Rexroth AG Basic principles and components. Chapter 5 • Technical data sheet RE 91001 Fixed displacement axial piston motor 05 . the trainee is to get familiar with the operating features of a hydraulic motor. a hydraulic motor is used. into hydraulic energy. In the project order. he/she is to understand the following: • Hydraulic motors convert hydraulic energy into torque and speed. which is fed to the pump via a drive shaft. • The speed of the hydraulic motors is determined by the flow provided and by the swept volume of the hydraulic motors. which is steplessly adjustable by means of appropriate control systems. Hydraulic pumps convert the mechanical energy. The following Project 05: Hydraulic motor is intended to gain knowledge of the operating principle and the use of hydraulic motors. If you connect a hydraulic pump directly to a hydraulic motor in a closed circuit you get a hydrostatic gearbox. 4/3 directional valves can be used to implement clockwise and counter-clockwise running of the hydraulic motor.Project 05: Hydraulic motor  Bosch Rexroth AG I RE 00845/04. The speed of the hydraulic motor can be changed by means of a meter-in throttle. Through this project task. In functional terms. radial piston and axial piston motors. vane. Hydraulic motors are distinguished by their design principle: Gear. By the control to be set up on the training system. gear wheel/planetary gear. a hydraulic motor is a hydraulic pump. which works in the opposite direction and with which both directions of rotation are possible. the trainee can recognize the operating principle of a hydraulic motor. a hydraulic motor is the inversion of a hydraulic pump. • The direction of rotation or the direction of flow of hydraulic motors can be controlled by means of a directional valve. For a positioned standstill of the hydraulic motor the return line (T) of the 4/3 directional valve is pre-loaded by means of a pressure relief valve. 07 Project definition Heavy loads are to be lifted and lowered by means of a rope winch. the rope winch must be powered by a hydraulic motor. 05. Also an electrical solution is not desirable due to changing loads.Project 05: Hydraulic motor  Bosch Rexroth AG I RE 00845/04. i. In order that the customer can understand the hydraulic solution proposed. he requires technical documentation such as a hydraulic circuit diagram with parts list and the required measured data such as an evaluation of the differential pressure across the hydraulic motor at different flows. For space reasons. the use of a hydraulic cylinder is impossible. Fig. The velocity of the rope winch is to be adjustable.1 Practical example: Winch for lifting heavy loads Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet of a hydraulic motor (specialist qualification) • Handling of hydraulic components in line with functional needs 05 .e. • Planning: Planning and organizing the execution of the customer order. Working out and documenting the system parameters required by the customer. through discussions with the customer. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? 05 . among others. • Executing: Set-up of the hydraulic control on the training system. • Deciding: Preparation of a schematic diagram sketch and selection of components.07 Project steps Notes • Informing: Accepting and understanding the order. through the selection of hydraulic components from the data sheet collection (RE 91001 Axial piston motor). among others.Project 05: Hydraulic motor  Bosch Rexroth AG I RE 00845/04. Project 05: Hydraulic motor  Bosch Rexroth AG I RE 00845/04.07 Hydraulic circuit diagram Item 0.2 Item 0.3 Item 1.0 05 Item 1.1 Item 0.4 Item 1.4 Item 1.3 Item 0.1 Item 1.2 Power unit limit Fig. 05.2 Hydraulic circuit diagram: Lifting platform control Measuring glass Project 05: Hydraulic motor  Bosch Rexroth AG I RE 00845/04.07 Electrical circuit diagram 05 Stop Control 4/3 directional valve Fig. 05.3 Wiring diagram for hydraulic circuit diagram Fig. 05.2 Rotation Rotation -Hydraulic motor- Project 05: Hydraulic motor  Bosch Rexroth AG I RE 00845/04.07 Component selection with parts list Item Qty 1.0 1 Fixed displacement motor with external leakage line and two directions of rotation 1.1 1 4/3 directional valve with direct actuation by two solenoids, spring centering of the central position and central position P, T, A, B DW 13 E 1.2/1.4 2 Direct operated pressure relief valve; the cracking pressure can be adjusted by means of a spring DD 1.1 1.3 1 Throttle valve, adjustable DF 1.2 1 Distributor plate with four ports DZ 4.1 4 Pressure gauge with hose and quick release coupling without check valve DZ 1.4 4 Hose with quick release coupling with check valve DZ 25.1 0.1 - 0.4 Component designation Hose 1 Stopwatch 1 Tachometer 1 Flowmeter Table 05.1 Parts list for hydraulic circuit diagram Fig. 05.2 Type designation Symbol DM 8 05 VSK 1 DZ 30 Project 05: Hydraulic motor  Bosch Rexroth AG I RE 00845/04.07 Component arrangement Connection block Measuring glass 05 D Note: In the case of connection elements marked with “D”, the components can be connected directly with each other. Fig. 05.4 Recommended component arrangement with component designations for parts list Table 05.1 and hydraulic circuit diagram Fig. 05.2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. Also the grid arrangement is Rexroth-specific and adapted for use on the training system. Notes Project 05: Hydraulic motor  Bosch Rexroth AG I RE 00845/04.07 Component arrangement/optional Note: The component arrangement shows the optional variant with electronic flow measurement Connection block Measuring glass 05 D Note: In the case of connection elements marked with “D”, the components can be connected directly with each other. Fig. 05.6 Recommended component arrangement with component designations for parts list Table 05.1 and hydraulic circuit diagram Fig. 05.2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. Also the grid arrangement is Rexroth-specific and adapted for use on the training system. Notes Project 05: Hydraulic motor  Bosch Rexroth AG I RE 00845/04.07 Safety notes To ensure the operability of plant and machinery, and consequently to allow the recognition of potential risks, safety regulations must be observed before and during the execution of the order. Relevant sources of regulations are given in the introduction of the present manual. Warning Caution If work on electrohydraulic components is carried out improperly, risks of injury and a safety risk can arise during operation of the system, including danger to life. Before starting work on the training stand, check that the electrical ON/ OFF switch on the hydraulic power unit is pressed in, i.e. that the system is switched off. Use the system pressure gauges to check that the system is depressurized. Hydraulic systems can store pressure energy when at rest. It can cause injury when the system is opened. Execution of the order Set up the control as described below: 1. Mount the components required according to Table 05.1 in a clearly arranged form on the training system according to the prepared circuit diagram. Connect the hydraulic control according to hydraulic circuit diagram Fig. 05.2 by means of hoses. For connections, to which pressure gauges with minimess line DZ 1.4 are to be connected, use hydraulic hoses DZ 25. Hand-tighten the pressure gauge measuring lines at the relevant minimess connection of the hydraulic hose. The correct and proper fit of the component connections with hoses can be checked by slightly turning the hoses. Warning Caution Make sure that all ports - in this case also minimess lines - pipes and hoses are connected or that the ports are blocked with plug screws or protective caps. Leakage oil can drop through open ports on the floor and cause a risk of slipping. Before commissioning the hydraulic control, i.e. before switching the hydraulic pump on, check, whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open. Wire the electrical control according to wiring diagram Fig. 05.3. 2. Switch the hydraulic pump on and inspect the set up control for leakage. No pressure gauge may indicate a pressure. 3. Check the set pressure on the variable displacement pump of the drive power unit (if required, correct to 50 bar). 4. Set the system pressure on pressure relief valve Item 1.2 to 50 bar plus one turn. Completely open throttle valve Item 1.3. 05 0 rotates clockwise.6 335 * 1 turn opened 48 25 21 4 17. Take care that clothes. Caution 5.2.1 is energized. hair. Measure all specified values for the clockwise direction of rotation. 8.2. Hydraulic motor Item 1.2 and enter the measurement result in Table 05.4. M3.7 655 * Table 05.7 435 * 1 ½ turn opened 48 30 25 5 18 4.3. While the hydraulic motor is rotating. M4 and enter them in Table 05. completely open throttle valve Item 1. Continue to set throttle valve Item 1.3 to the values given in Table 05. The values were measured at an oil temperature of approx.07 In the next working step the hydraulic motor rotates.3 M1 M2 M3 M2 . 05 .1 is energized. Use the measuring glass and a stopwatch or optionally an electronic flow measuring system to acquire the flow qV in l/min and enter the values in Table 05. etc. 7.Project 05: Hydraulic motor 10 Bosch Rexroth AG I RE 00845/04. 20 °C.5 2.2 Measured values from the work order for counter-clockwise direction of rotation of the motor * The values in column 8 were established by means of a speed sensor. M2. By actuating push-button S2 solenoid Y1a of 4/3 directional valves Item 1.M3 M4 qV n p in bar p in bar p in bar Dp in bar p in bar in l/min in min-1 Throttle closed 50 0 0 0 0 0 0 � turn opened 49 20 17. No pressure gauge may indicate a pressure! Measured values Adjustment of speed of rotation Throttle valve Item 1. By actuating push-button S4 solenoid Y1b of 4/3 directional valve Item 1.2 back to minimum pressure.2.3.2). 6. The values measured by the trainees can deviate by 10 %. cannot get caught by the motor plate. Close throttle valve Item 1. Also measure pressures M1. The hydraulic motor rotates counter-clockwise.5 15 2 264 * ½ turn opened 48 22 19 3 16 2.1 595 * More than 2 ½ turns opened 48 34 27 7 19 5. then open it by � turn (the first value given in Table 05. adjust preload pressure M4 to 20 bar by means of pressure relief valve Item 1. Caution After having completed practical work on the training system switch the hydraulic pump off! Turn pressure relief valve Item 1.7 540 * 2 turns opened 48 31 25 6 19 5.5 3. • The torque of hydraulic motors is determined by the differential pressure and the swept volume. P= qV = n= ∆ p • qV 600 in kW V • 60 t qV • ηvol Vg • 1000 P = output power in kW p = pressure in bar qV = swept volume in l/min V = content of the measuring glass in l t = measuring time in s n = drive speed in min-1 hvol = volumetric efficiency of the motor Vg = geometric swept volume (displacement) of the motor in cm3/rev hvol = 0.DM2 Evaluating the work results with regard to the customer requirement • Hydraulic motors convert hydraulic energiy into torque and speed.8 Vg = 4.Project 05: Hydraulic motor 11 Bosch Rexroth AG I RE 00845/04. • The direction of rotation of hydraulic motors can be controlled by means of a directional valve. 05 .93 cm3/rev . • The speed of hydraulic motors is determined by the supplied hydraulic pump flow and by the swept volume of the hydraulic motors.07 Additional tasks: Calculation of the output power at maximum speed using the formulas below. Project 05: Hydraulic motor 12 Bosch Rexroth AG I RE 00845/04.07 Notes 05 . 07 Project 06: 4/3 directional valve Project/trainer information If the travel. – the working pressure utilized last slowly decreases via the clearance of the spool when the hydraulic pump is switched off and the valve is in its rest position. The trainee can recognize the special features of different symbols by measuring the different pressure differentials across the 4/3 directional valve. the selection of the valve spool. – the total flow of a fixed displacement pump flows via the pressure relief valve to the tank when the set system pressure is reached while the pump is running and the valve is in its rest position. The following Project 06: 4/3 directional valve is intended to gain knowledge of the operating principle and the possible applications of direct operated directional valves. In the project order the trainee is to work out and document the following: • The spool shape determines the symbol. • With a valve being in the blocked position: – a connected single-rod cylinder can extend due to internal leakage of the valve while the valve is in its rest position and the pump is running. high power losses incur and the oil heats up. i. This feature cannot be installed in controls. The spool of a directional valve is installed with a certain clearance. 4/2 and 3/2 directional valves with wet pin solenoids 06 . pilot operated and directional poppet valves. Internal leakage can be recognized by the horizontal arrangement of the single-rod cylinder. This leakage. pressure/force losses occur on the hydraulic cylinder when the fluid flows through the valve. a directional valve must be used. Directional valves are elements that assume the task of opening.e. where the system pressure is required by further actuators. With the help of the control set up on the training system the trainee gets familiar with the possible application of a 4/3 directional valve. direct operated. – energy is saved while the pump is running and the valve is in its rest position. Notes on detailed technical information about direct operated directional valves: • The Hydraulic Trainer Volume 1/Bosch Rexroth AG • Technical data sheet RE 23178 4/3. direction. This clearance causes a continuous leakage oil flow. on which no external forces act. start. results in a flow loss that increases as the pressure rises. A hydraulic cylinder is to be controlled alternately by a 4/3 directional valve with different spool shapes (blocked and circulation position). The valve spool also determines the form of the symbol. and stop of a hydraulic cylinder is to be controlled in a hydraulic system. which is not externally visible. the backpressure and hence the power loss is determined by the pressure differential across the valve. • With a valve being in the circulation position: – when the valve is in its rest position and the pump is switched on the total pump flow flows almost at zero pressure to the tank.Project 06: 4/3 directional valve  Bosch Rexroth AG I RE 00845/04. closing or changing the flow paths in hydraulic systems. Possible applications and the operating characteristics of the directional valve are determined by. among others. When a directional valve is used for controlling a hydraulic cylinder. Directional valves are differentiated as follows: Directional spool valves. and all directional spool valves feature internal leakage for design reasons caused by the clearance of the spool in the valve housing. In order that the customer can understand your proposed solution. and the required measured data for the spool shapes/symbols. When in the rest position the hydraulic cylinder must not move.Project 06: 4/3 directional valve  Bosch Rexroth AG I RE 00845/04. 06 Fig. he requires technical documentation such as the hydraulic circuit diagram with parts list. The customer wants to be informed about the pros and cons of the various spool shapes.07 Project definition A single-rod cylinder is to shift and position tools horizontally in a fixture.1 Practical example: Section of a 4/3 directional valve Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet of a directional valve (specialist qualification) • Handling of hydraulic components in line with functional needs . 06. in particular blocked and circulation position. and the fixed displacement pump is to be spared and thus energy saved. through the selection of hydraulic components from the data sheet collection (RE 23178/4/3 directional valve). Working out and documenting the system parameters as required by the customer.Project 06: 4/3 directional valve  Bosch Rexroth AG I RE 00845/04. through discussions with the customer. among others. among others. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? 06 . • Executing: Set-up of the hydraulic control on the training system.07 Project steps Notes • Informing: Accepting and understanding the order. • Planning: Planning and organizing the execution of the customer order. • Deciding: Preparation of a schematic diagram sketch and selection of components. 3 Power unit limit Fig.1 Item 1.2 Hydraulic circuit diagram: Tool carriage control 1 Measuring glass . 06.1 Item 0.Project 06: 4/3 directional valve  Bosch Rexroth AG I RE 00845/04.0 Item 0.07 Hydraulic circuit diagram/task 1 Item 1.3 06 Item 1.2 Item 0. 3 Wiring diagram for hydraulic circuit diagram Fig.07 Electrical circuit diagram/task 1 06 Circulation Control 4/3 directional valve Fig. 06.Project 06: 4/3 directional valve  Bosch Rexroth AG I RE 00845/04. 06.2 Extension Retraction -Single-rod cylinder- . Project 06: 4/3 directional valve  Bosch Rexroth AG I RE 00845/04.0 Item 0. 06.2 Item 0.3 Power unit limit Fig.3 06 Item 1.1 Item 1.4 Hydraulic circuit diagram: Tool carriage control 2 Measuring glass .2 Item 0.07 Hydraulic circuit diagram/task 2 Item 1. Project 06: 4/3 directional valve  Bosch Rexroth AG I RE 00845/04. 06.07 Electrical circuit diagram/task 2 06 Stop Control 4/3 directional valve Fig.5 Wiring diagram for hydraulic circuit diagram Fig.4 Retraction Extension -Single-rod cylinder- . 06. N . B DW 13E 1.07 Component selection with parts list Item Qty 1. the cracking pressure can be adjusted by means of a spring DD 1.1 Parts list for hydraulic circuit diagrams Fig.0.1 1 Distributor plate with four ports DZ 4.T.2 and 06.1 0. A.3 1 4/3 directional valve with direct actuation by two solenoids. spring centering of the central position and central position P. B DW 4E 1.3 1 Direct operated pressure relief valve.4 3 Hose with quick release coupling with check valve DZ 25 Hose VSK 1 1.0 1 Double-acting cylinder with single-sided piston rod ZY 1.2 1 4/3 directional valve with direct actuation by two solenoids. spring centering of the central position and central position P .1 3 Pressure gauge with hose and quick release coupling without check valve DZ 1. T.04 Type designation Symbol 06 DZ 30. 06. A.Project 06: 4/3 directional valve  Bosch Rexroth AG I RE 00845/04.1 .3 1 Component designation Flowmeter Table 06. 06. 06. Also the grid arrangement is Rexroth-specific and adapted for use on the training system. Notes .6 Recommended component arrangement with component designations for parts list Table 06.1 and hydraulic circuit diagram Fig.Project 06: 4/3 directional valve  Bosch Rexroth AG I RE 00845/04.02 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations.07 Note: The component arrangement shows the optional variant with electronic flow measurement Connection block Measuring glass Component arrangement/task 1 06 D Note: In the case of connection elements marked with “D”. Fig. the components can be connected directly with each other. Fig. 06.4 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations.Project 06: 4/3 directional valve 10 Bosch Rexroth AG I RE 00845/04. Also the grid arrangement is Rexroth-specific and adapted for use on the training system.1 and hydraulic circuit diagram Fig. Notes .07 Note: The component arrangement shows the optional variant with electronic flow measurement Connection block Measuring glass Component arrangement/task 2 06 D Note: In the case of connection elements marked with “D”. the components can be connected directly with each other.8 Recommended component arrangement with component designations for parts list Table 06. 06. The correct and proper fit of the component connections with hoses can be checked by slightly turning the hoses. Relevant sources of regulations are given in the introduction of the present manual. safety regulations must be observed before and during the execution of the order. that the system is switched off. It can cause injury when the system is opened. i. and consequently to allow the recognition of potential risks. 3.07 Safety notes To ensure the operability of plant and machinery. before switching the hydraulic pump on.4 are to be connected.3 to 30 bar. For connections. whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open. Switch the hydraulic pump on and inspect the set up control for leakage. Warning Caution Make sure that all ports . check. Connect the hydraulic control according to hydraulic circuit diagram Fig.Project 06: 4/3 directional valve 11 Bosch Rexroth AG I RE 00845/04. 06. check that the electrical ON/ OFF switch on the hydraulic power unit is pressed in. Wire the electrical control according to wiring diagram Fig. i.in this case also minimess lines . Hydraulic systems can store pressure energy when at rest. 06. Warning Caution If work on electrohydraulic components is carried out improperly. Mount the components required according to Table 06. Hand-tighten the pressure gauge measuring lines at the relevant minimess connection of the hydraulic hose. Before commissioning the hydraulic control.pipes and hoses are connected or that the ports are blocked with plug screws or protective caps. risks of injury and a safety risk can arise during operation of the system. Execution of the order Task 1 Set-up of the controls as described below: 1. 4. The piston of the hydraulic cylinder extends. Before starting work on the training stand. By actuating push-button S2 solenoid Y1a of 4/3 directional valve Item 1. Use the system pressure gauges to check that the system is depressurized.e. 2. including danger to life.3.1 is energized. The pump flow is fed against the piston rod side of hydraulic cylinder Item 1. 06 .2 by means of hoses. Set the system pressure on pressure relief valve Item 1.0 and the system pressure can be set to 30 bar. to which pressure gauges with minimess line DZ 1.1 in a clearly arranged form on the training system according to the prepared circuit diagram. Leakage oil can drop through open ports on the floor and cause a risk of slipping.1 is energized. use hydraulic hoses DZ 25. No pressure gauge may indicate a pressure. and: By actuating push-button S4 solenoid Y1b of 4/3 directional valve Item 1.e. In contrast to task 1. No pressure gauge may indicate a pressure! 6.4.66 Piston retracted b 30 0 30 7. Caution After having completed practical work on the training system switch the hydraulic pump off! Turn pressure relief valve Item 1.2 and enter the values in Table 06.3 and enter the values in Table 06. 7.66 Rest position of piston 0 8 5 8 0 Table 06.3 to 30 bar. No pressure gauge may indicate a pressure. By actuating push-button S2 the piston of the hydraulic cylinder retracts.2 is energized. Measure the specified values in the end positions of the hydraulic cylinder and in the rest position (central position) of the 4/3 directional valve as listed in Table 06. Proceed as described in task one. The piston of hydraulic cylinder Item 1. Caution Task 2 After having completed practical work on the training system switch the hydraulic pump off! Turn pressure relief valve Item 1. Modify the hydraulic control according to hydraulic circuit diagram 06. steps 1 and 2. No pressure gauge may indicate a pressure. Check the electrical control for correct wiring. 9.3 back to minimum pressure. Set the system pressure on pressure relief valve Item 1. By actuating push-button S4 solenoid Y1b of 4/3 directional valve Item 1. Measure the specified values in the end positions of the hydraulic cylinder and in the rest position (central position) of the 4/3 directional valve as listed in Table 06. Measurements for task 2: 10.3 back to minimum pressure. 8. Measured values for task 1 Hydraulic cylinder Position Directional valve position M1 p in bar M2 p in bar M3 p in bar qV in l/min Piston extended a 30 30 0 7.3.07 Measurements for task 1: 5. positions "a“ and "b“ of the 4/3 directional valve are exchanged due to the spool shape/symbol.Project 06: 4/3 directional valve 12 Bosch Rexroth AG I RE 00845/04.2.2 4/3 directional valve with circulation position 06 .1 extends. Switch the hydraulic pump on and inspect the set up control for leakage. The hydraulic fluid heats up and a high power loss incurs. is determined by the spool shape of the directional valve and by line resistances in the return line.Project 06: 4/3 directional valve 13 Bosch Rexroth AG I RE 00845/04. and hence the power loss. the total flow of a fixed displacement hydraulic pump is fed via the pressure relief valve to the tank in the rest/central position of the directional valve when the system pressure is reached.66 Table 06.66 Piston at rest position 0 30 7 9 7. • With a 4/3 directional valve with blocked position a connected single-rod cylinder can extend due to internal leakage oil while the directional valve is in its rest position and the fixed displacment pump is running.66 Piston retracted a 30 0 30 7. 20 °C.07 Measured values for task 2 Hydraulic cylinder Position Directional valve position M1 p in bar M2 p in bar M3 p in bar qV in l/min Piston extended b 30 30 0 7. • With a 4/3 directional valve with blocked position. . The working pressure utilized last slowly decreases via the clearance between spool/ housing. but this valve can not be used. energy is saved due to the pressureless circulation in der central position. The values measured by the trainees can deviate by 10 %. The pressure differential.3 4/3 directional valve with blocked position 06 The values were measured at an oil temperature of approx. if further actuators are to be controlled by an additional directional valve. • With a 4/3 directional valve with circulation position. Evaluating the work results with regard to the customer requirement • With a 4/3 directional valve with circulation position the total flow of the hydraulic pump is fed back to the tank almost at zero pressure when the directional valve is in its rest/central position. Project 06: 4/3 directional valve 14 Bosch Rexroth AG I RE 00845/04.07 Notes 06 . Through this project tasks he/she is to recognize the following: • Fluid can only flow through a check valve in one direction. Through the installation of a check valve it is possible to prevent. with ball or poppet as closing element. can be lowered by operating a shut-off valve. Notes on detailed technical information about the check valve: • The Hydraulic Trainer Volume 1/Bosch Rexroth AG Basic principles and components. Also pressure peaks. The cylinder velocity can be adjusted by means of a throttle. A hydraulic cylinder under load. pilot operated check valves.07 Project 07: Check valve Project/trainer information If the flow in hydraulic system is to be blocked in one direction. The following Project 07 can be used to impart knowledge of the operating principle and the use of a check valve. • A check valve results in additional hydraulic resistance in the system. the use of a check valve also results in additional resistance in the system so that a greater power must be installed. In the course of the project order the trainee is to understand the operating principle of a check valve installed in a by-pass. However. a check valve is required. They are subdivided as follows: Check valves. for example. Chapter 10 • Technical data sheet RE 20375 Check valve 07 .g. can be reduced by means of a check valve installed in a by-pass. • When loads are secured by a check valve on the piston rod side. the load pressure from driving a hydraulic pump reversely when the electric motor is switched off.Project 07: Check valve  Bosch Rexroth AG I RE 00845/04. On the basis of the control set up on the training system the trainee is to understand the operating principle of a check valve. Check valves are available as seat valves. To provide protection against pressure intensification a pressure relief valve is to be installed on the piston rod side. which is secured by a check valve. e. • Pressure peaks can be reduced with the help of a check valve installed in a by-pass. upstream of filters or coolers. there is a risk of pressure intensification. a load suspended on a vertical cylinder is to be held by means of a check valve. (The lowering movement via the electrical control is not an integral part of the order).1 Practical example: Check valve Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet of a check valve (specialist qualification) • Handling of hydraulic components in line with functional needs .07 Project definition In a fixture. In order that the customer can understand your proposed solution. 07. The velocity is to be adjustable. he requires technical documentation.Project 07: Check valve  Bosch Rexroth AG I RE 00845/04. he wants to know whether particular problems could arise. Lowering of the load should be possible with a shut-off valve. The piston rod side is to be protected by means of a pressure relief valve. if a check valve is installed on the piston rod side. In addition. 07 Fig. Project 07: Check valve  Bosch Rexroth AG I RE 00845/04. • Executing: Set-up of the hydraulic control on the training system. Working out and documenting the system parameters requred by the customer. among others. • Deciding: Preparation of a schematic diagram sketch and selection of components. • Planning: Planning and organizing the execution of the customer order.07 Project steps Notes • Informing: Accepting and understanding the order. through discussions with the customer. among others. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? 07 . through the selection of hydraulic components from the data sheet collection (RE 20375 Check valve). 2 Item 1.0 Item 0.5 Item 1.2 Hydraulic circuit diagram: Control of a vertical cylinder with suspended load Measuring glass .3 Item 1. 07.6 Item 0.3 07 Item 1.4 Item 1.Project 07: Check valve  Bosch Rexroth AG I RE 00845/04.2 Power unit limit Fig.1 Item 0.07 Hydraulic circuit diagram Item 1.1 Item 1. b is not energized Fig.07 Electrical circuit diagram 07 (Emergency stop) Stop Control 4/3 directional valve Retraction -Single-rod cylinder* Solenoid Y1.Project 07: Check valve  Bosch Rexroth AG I RE 00845/04.3 Wiring diagram re hydraulic circuit diagram 07.2 . 07. 07.1 3 Pressure gauge with hose and quick release coupling without check valve DZ 1.Last 07 . actuated by turning DZ 2.4 3 Hose with quick release coupling with check valve DZ 25 Hose VSK 1 0.2 Type designation Symbol ZY 1.0.Project 07: Check valve  Bosch Rexroth AG I RE 00845/04. spring centering of the central position and central position P.T DW 10E 1.2 3 Distributor plate with four ports DZ 4. rest position closed.3 Component designation Table 07. flow possible in only one direction.3 1 Check valve with spring.5 2 Direct operated pressure relief valve. cracking pressure 1 bar DS 2. adjustable DF 1. A .B .1 1.6 1 Throttle valve. the cracking pressure can be adjusted by means of a spring DD 1.0 1 Double-acting cylinder with single-sided piston rod with load 1.4 1 Shut-off valve.1 Parts list for hydraulic circuit diagram Fig.07 Component selection with parts list Item Qty 1.2/1.1 1.1 1 4/3 directional valve with direct actuation by two solenoids.1 .1 1. 07. . Also the grid arrangement is Rexroth-specific and adapted for use on the training system. Fig. the components can be connected directly with each other. 07.2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations.1 and hydraulic circuit diagram Fig.Project 07: Check valve  Bosch Rexroth AG I RE 00845/04.07 Measuring glass Component arrangement Connection block 07 D Note: In the case of connection elements marked with “D”.4 Recommended component arrangement with component designation for parts list Table 07. i. Wire the electrical control according to wiring diagram Fig. i. Warning Caution Make sure that all ports .in this case also minimess lines . 3.2 to 50 bar plus one turn (in pressure line M1). check that the electrical ON/ OFF switch on the hydraulic power unit is pressed in. that the system is switched off. Set the system pressure on pressure relief valve Item 1. including danger to life. Warning Caution If work on electrohydraulic components is carried out improperly. Leakage oil can drop through open ports on the floor and cause a risk of slipping. Before commissioning the hydraulic control. Hydraulic systems can store pressure energy when at rest.e. use hydraulic hoses DZ 25. 07. before switching the hydraulic pump on.pipes and hoses are connected or that the ports are blocked with plug screws or protective caps.Project 07: Check valve  Bosch Rexroth AG I RE 00845/04. For connections. Relevant sources of regulations are given in the introduction of the present manual. Before starting work on the training stand. to which pressure gauges with minimess line DZ 1. It can cause injury when the system is opened. check.07 Safety notes To ensure the operability of plant and machinery. safety regulations must be observed before and during the execution of the order. Execution of the order Set up the control as described below: 1.4 are to be connected. whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open.1 in a clearly arranged form on the training system according to the prepared circuit diagram. 07 . Observe the installation direction of check valve Item 1. Warning 2. risks of injury and a safety risk can arise during operation of the system.3. 07. The correct and proper fit of the component connections with hoses can be checked by slightly turning the hoses.2 by means of hoses. Use the system pressure gauges to check that the system is depressurized.e. Switch the hydraulic pump on and inspect the set up control for leakage. Connect the hydraulic control according to hydraulic circuit diagram Fig. Mount the components required according to Table 07. Hand-tighten the pressure gauge measuring lines at the relevant minimess connection of the hydraulic hose. No pressure gauge may indicate a pressure.3. and consequently to allow the recognition of potential risks. 1 by manual operation to position Y1b while opening pressure relief valve Item 1.D.C. Move directional valve Item 1.6. e.g. On the basis of the load holding pressure and the dimensions of the hydraulic cylinder the weight of the load can be calculated.g.4 causes the cylinder to extend. • A check valve can be used as safety valve. • The installation of a check valve results in the build-up of additional resistance in the direction of flow. M3 indicates the load holding pressure. (bottom dead center. For the disassembly.4. the load must be lowered. The upward stroke is accomplished via a check valve installed in parallel. i. 5. While the shut-off valve is closed. The lowering velocity can be adjusted by means of throttle valve Item 1. Close shut-off valve Item 1. Check lowering of the load in the de-energized condition by opening shut-off valve Item 1. • Load securing by means of a check valve on the piston rod side involves the risk of pressure intensification. By actuating push-button S2 solenoid Y1a of 4/3 directional valve Item 1.1 turn). Check the set value by extending the cylinder again. to provide protection against pressure peaks. slowly open the pressure relief valve until the cylinder starts to lower. Safety valve setting against pressure intensification on the piston rod side: Starting position of the cylinder: B.07 4.5 on the piston rod side to maximum pressure (spring tensioned . 07 . in a welding fixture. Note: To prevent pressure intensification. the cylinder retracts. a safety valve (pressure relief valve) is used in practical applications. No pressure gauge may indicate a pressure! Evaluating the work results with regard to the customer requirement • Fluid can flow through a check valve only in one direction. the cylinder must be at the U. Set pressure relief valve Item 1.e.D.5 on the piston rod side is called load holding pressure. Caution After having completed practical work on the training system switch the hydraulic pump off! Set the throttle valve and the pressure relief valves to minimum pressure.C.D. e.Project 07: Check valve  Bosch Rexroth AG I RE 00845/04. To determine the load holding pressure.4. cylinder extended). 6. Move the cylinder to the U. by operating push-button S2.1 is energized.5 on the piston rod side until pressure gauge M3 indicates a pressure of 80 bar (safety setting against pressure intensification on the piston rod side). Opening of shut-off valve Item 1. The pressure that builds up when the cylinder supports on the counterforce of pressure relief valve Item 1.C. 07 Notes 07 .Project 07: Check valve 10 Bosch Rexroth AG I RE 00845/04. • To prevent decompression shocks when the check valve opens.Project 08: Check valve. pilot operated check valves can also be opened in the direction opposite to the direction of flow (direction of closure). Bosch Rexroth AG Basic principles and components. pilot operated  Bosch Rexroth AG I RE 00845/04. With the help of a practice-oriented experiment set-up on the training system he/she is to undertand the following: • Fluid can only flow through a hydraulically pilot operated check valve in the checking direction. In the following Project 08 you can impart knowledge of the operating principle and the use of a pilot operated check valve.07 Project 08: Check valve. components are used that feature a pre-opening function of the main poppet. Pilot operated check valves can be installed for isolating pressurized working circuits (hydraulic isolation of a hydraulic cylinder) or for providing protection against lowering of a load in the event of a line rupture. A hydraulic cylinder under load (vertical cylinder with suspended load) is secured by a pilot operated check valve. chapter 10 • Technical data sheet RE 21460 Check valve 08 . This pilot operated check valve is opened by means of a 4/2 directional valve. the trainee has to make himself/herself familiar with the operating principle of a pilot operated check valve. when it is opened by an additional hydraulic control signal. if the fluid can freely flow from the closing element to the reservoir. The lowering speed can be adjusted with a throttle. • The check valve can only be closed when the pilot line is depressurized. pilot operated Project/trainer information In contrast to simple check valves. A pressure relief valve on the piston rod side provides a pressure relief function for pressure intensifications. Notes on the detailed technical information about the direct operated pressure relief valve: • The Hydraulic Trainer Volume 1. the trainee can see the operating principle of a pilot operated check vave. In the project order. if it is opened by means of a hydraulic control signal. • The check valve can only close properly. With the help of a control set up on the training system for a lifting apparatus. In order that the customer can understand your proposed solution. pilot operated  Bosch Rexroth AG I RE 00845/04.Project 08: Check valve. the customer wants to know. Moreover. 08 Fig. 08. The hydraulic control from Project 07 is to be modified according to the customer requirements. he requires the modified technical documentation. at which position the throttle valve can be installed. he wants to know at which pilot pressure the pilot operated check valve opens. As the lowering speed should also be adjustable here.1 Practical example: Hydraulically pilot operated check valves in a rig (gripper) Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet for a pilot operated check valve (technical qualification) • Handling of hydraulic components in line with functional needs .07 Project definition A cylinder in a rig (gripper) is to be protected against lowering by a pilot operated check valve. among others. • Executing:: Preparation of a schematic circuit diagram and selection of the required drive elements and accessories with short description. pilot operated  Bosch Rexroth AG I RE 00845/04. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? 08 . among others. through the selection of hydraulic components from the data sheet collection (RE 21460 / pilot operated check valve).07 Project steps Notes • Informing: Accepting and understanding the order.Project 08: Check valve. through discussions with the customer. • Planning: Planning and organizing the execution of the customer order. • Deciding: Preparation of a circuit diagram sketch and selection of components. 0 Item 0. hydraulically pilot operated Measuring glass .Project 08: Check valve.07 Hydraulic circuit diagram Item 1.3 Item 1.3 Item 1. 08.2 Item 1. pilot operated  Bosch Rexroth AG I RE 00845/04.1 Item 0.4 Item 1.2 Power unit limit Fig.1 Item 1.5 08 Item 1.6 Item 0.2 Hydraulic circuit diagram: Check valve. Project 08: Check valve.3 Wiring diagram for hydraulic circuit diagram 08.2 .07 Electrical circuit diagram Stop 08 Control 4/3 directional valve . pilot operated  Bosch Rexroth AG I RE 00845/04. 08.4/2 directional valve Retraction Extension Unlocking -Single-rod cylinder- Note: Extension = Y1.b + Y2 Fig. A . with check valve DZ 25 Hose VSK 1 0.1 3 Pressure gauge with hose and quick-release coupling. pilot operated  Bosch Rexroth AG I RE 00845/04. without check valve DZ 1.0.2 Type designation Symbol 08 .Last 1.B .3 1 4/2 directional valve with solenoid operation.07 Component selection with parts list Item Qty 1. spring return DW 3E 1. flow possible in both directions due to pilot pressure DS 1.1 1.4 1 Pilot operated check valve.5 2 Direct operated pressure relief valve. the cracking pressure can be adjusted by means of a spring DD 1.1 1 4/3 directional valve with direct actuation by two solenoids. 08.4 3 Hose with quick-release coupling.1 . spring centring of the central position and central position P.2 3 Distributor plate with four connections DZ 4.1 1.0 1 Double-acting cylinder with piston rod with load on one side ZY 1.Project 08: Check valve.2/1. adjustable DF 1.3 Component designation Table 08.T DW 10E 1.1 Parts list for hydraulic circuit diagram Fig.6 1 Throttle valve. with spring. 4 Recommended component arrangement with component designations for parts list Table 08.07 Measuring glass Component arrangement Connection block 08 D Note: In the case of connection elements marked with “D”. the components can be connected directly with each other.2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. .Project 08: Check valve. 08. Fig. pilot operated  Bosch Rexroth AG I RE 00845/04.1 and hydraulic circuit diagram Fig. Also the grid layout is Rexroth-specific and adapated for use on the training system. 08. safety regulations must be observed before and during the execution of the order. Before commissioning the hydraulic control.e. Hand-tighten the pressure gauge measuring lines hand tight at the relevant minimess connection of the hydraulic hose. i. 08. including danger to life. 4. The operation of pushbutton S2 causes the energization of solenoid Y1a of 4/3 directional valve item 1. pilot operated  Bosch Rexroth AG I RE 00845/04. Mount the components required according to Table 08. 08. make sure that electrical ON/OFF switches on the hydraulic power unit are pressed in. Wire the electrical control according to wiring diagram Fig. . use hydraulic hoses DZ25.3.in this case also to minimess lines. No pressure gauge may indicate a pressure. Hydraulic systems can store pressure energy at rest. Relevant sources of regulations are given in the introduction of the present manual.2 by means of hoses. For connections. the cylinder retracts.e.07 Safety notes To ensure the operability of plant and machinery. 2. whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open. that is. or that the connections are plugged by means of plug screws or protective caps. check.2 to 50 bar plus one turn.5 in until the cylinder starts to move.Project 08: Check valve. Before starting work on the training stand. risks of injury and a safety risk can arise operation of the system. Check on the system pressure gauge that the system is depressurized. Switch the hydraulic pump on and check the set up control for leakage. 3. Leakage oil may drip through open connections and cause a slipping risk.1.1 on the training system in a clearly arranged manner according the prepared circuit diagram. Turn item 1. Warning Caution Make sure that pipes or hoses are connected to all connections . and consequently to allow the recognition of potential risks.4 are to be connected. i. 08 Execution of the order Set-up of the control as described in the following: 1. This can cause injury when the system is opened. before switching the hydraulic pump on. to which pressure gauges with minimess hose DZ 1. Adjust the system pressure on pressure relief valve item 1. The proper and tight fit of hose connections of components can be easily checked by slightly turning the hoses. that the system is switched off. Connect the hydraulic control according to hydraulic circuit diagram Fig. Warning Caution If work on electrohydraulic components is carried out improperly. M2 and M3 during operation and enter the values in Table 08. then turn pressure relief valve out until 80 bar is applied at M3. Caution Notes Before converting the circuit for the further execution of the order. The actuation of pushbutton S3 causes 4/3 directional valve item 1.4 controlled via 4/2 directional valve item 1. turn in pressure relief valve completely. 6. Only when pushbutton S4 is operated additionally is port X of pilot operated check valve item 1. i.6.07 Only operate S3. The piston cannot extend. Caution While the throttle is open and the piston is lowering. Set the lowering speed of the cylinder to a lowering time of approx.2. the movement of the piston may be very jerky. 5. The piston can advance due to the load on the vertical cylinder.1 to be operated. Measure the pressures in M1. switch the hydraulic pump off! 08 . The cylinder is to come to a standstill. the valve closes abruptly. 7. This causes underpressure in the piston chamber and hence an absence of pilot pressure at port X of the pilot operated check valve.3 and the check valve opens. Fluid can now flow at zero pressure from the piston rod side via 4/3 directional valve item 1. M2 and M3 and enter the values in Table 08.e. When pressure is built up again on the piston side. pressure is supplied to the the piston side of the hydraulic cylinder.Project 08: Check valve. pilot operated  Caution Bosch Rexroth AG I RE 00845/04. The check valve opens abruptly. 5 s on throttle valve item 1. i.2.1 to the reservoir. Measure the pressures at M1. port X on the check valve is again supplied with pilot pressure.e. • The pilot operated check valve can only close properly.07 Measured values M1 p in bar M2 p in bar M3 p in bar Lower cylinder via the pressure relief valve 45 45 70 Lower cylinder via the check valve 20 10 15 Measuring point Table 08. pilot operated 10 Bosch Rexroth AG I RE 00845/04. if it was opened by means of a hydraulic control signal. . No pressure gauge may indicate a pressure! Evaluating the work results with regard to the customer requirement • Fluid can only flow through a hydraulically pilot operated check valve in the checking direction. • To prevent decompression shocks during opening of the check valve. when the pilot line is depressurized. components with a pre-opening feature of the main poppet are used (development of theoretical knowledge).2 Lowering pressures The values were measured at an oil temperature of approx.Project 08: Check valve. when the fluid can freely flow away from the closing element. switch the hydraulic pump off! Set the throttle valve and the pressure relief valves to minimum pressure. The values measured by trainees can deviate by 10 %. 08 Caution After having completed the practical work on the training system. 20 °C. • The pilot operated check valve can only close. Chapter 13 • Technical data sheet RE 27219 Throttle valve type MG 09 . Notes on detailed technical information about the throttle valve: • The Hydraulic Trainer Volume 1/Bosch Rexroth AG Basic principles and components. As a result of the pressure drop. • the flow is independent of the pressure level when the pressure differential Dp is constant. he/she is to understand that: • the differential pressure Dp rises while the flow increases and the throttling cross-section remains constant. By changing the throttle settings. Flow control valves are classified in: Throttle . The flow provided by the hydraulic pump can be controlled with the help of flow control valves. In the project order the trainee is to work out and document the characteristic curve of a throttle. The control set up on the training system allows the trainee to measure various differential pressures across the throttle valve at certain flows. In the following Project 09 knowledge is to be imparted with regard to the operating principle and the use of throttle valves. adjustable Project/trainer information In hydraulic systems the piston velocity of a hydraulic cylinder or the revving speed of a hydraulic motor should often be adjustable. • the differntial pressure Dp rises in proportion to the reduction in the throttling cross-section while the flow remains constant. Dp across the throttling point. adjustable  Bosch Rexroth AG I RE 00845/04. The task of a throttle valves is to offer a flow resistance by changing the flow cross-section.fine throttle/orifice and flow control valve. A load can be simulated by installing a pressure relief valve in the return line of the 4/3 directional valve.07 Project 09: Throttle valve. the flow and consequently the speed of the actuator changes.Project 09: Throttle valve. he wants to know whether the drive speed changes when loads of different weights are transported. The drive speed of the hydraulic motor is to be adjustable in both directions of travel. adjustable  Bosch Rexroth AG I RE 00845/04. As an option. In order that the customer can understand the proposed solution. on which unchanged loads are transported. is powered by a hydraulic motor.07 Project definition In the plant of the customer. 09. a conveyor belt. 09 Fig. he requires technical documentation.1 Practical example: Conveyor belt for transporting printed-circuit boards Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet of a throttle valve (specialist qualification) • Handling of hydraulic components in line with functional needs .Project 09: Throttle valve. • Deciding: Preparation of a schematic diagram sketch and selection of components.Project 09: Throttle valve. among others. adjustable  Bosch Rexroth AG I RE 00845/04. Working out and documenting the system parameters requred by the customer. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? 09 Notes . • Executing: Set-up of the hydraulic control on the training system.07 Project steps • Informing: Accepting and understanding the order. among others. through discussions with the customer. • Planning: Planning and organizing the execution of the customer order. through the selection of hydraulic components from the data sheet collection (RE 27219 Throttle check valve). 1 Item 1. adjustable Measuring glass .07 Hydraulic circuit diagram Item 0.4 Load pressure Item 0. 09.Project 09: Throttle valve.0 Item 1.3 Item 1.2 Item 0.5 Item 1.1 Optional 09 Item 1.2 Power unit limit Fig. adjustable  Bosch Rexroth AG I RE 00845/04.3 Item 1.2 Hydraulic circuit diagram: Throttle valve. 07 Electrical circuit diagram Stop 09 Control 4/3 directional valve Fig. 09.3 Wiring diagram for hydraulic circuit diagram Fig. 09.2 Rotation Rotation -Hydraulic motor- .Project 09: Throttle valve. adjustable  Bosch Rexroth AG I RE 00845/04. adjustable DF 1.2 2 Distributor plate with four ports DZ 4. 09. the cracking pressure can be adjusted by means of a spring DD 1.0.2 Type designation DFF 1 Symbol 09 . adjustable  Bosch Rexroth AG I RE 00845/04. A.Project 09: Throttle valve.3 1 Throttle valve.3 Component designation 1 Stopwatch 1 Flowmeter Table 09.07 Component selection with parts list Item Qty 1.0 1 Fixed displacement motor with external leakage line and two directions of rotation DM 2.1 1 4/3 directional valve with direct actuation by two solenoids.1 .1 1.2/1.4 3 Hose with quick release coupling with check valve DZ 25 Hose VSK 1 0. T.1 Parts list for hydraulic circuit diagram Fig. spring centering of the central position and central position P.N 1. B DW 13E 1.1 4 Pressure gauge with hose and quick release coupling without check valve DZ 1.4 2 Direct operated pressure relief valve. adjustable  Bosch Rexroth AG I RE 00845/04.1 and hydraulic circuit diagram Fig.2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations.Project 09: Throttle valve.4 Recommended component arrangement with component designation for parts list 09. 09. Also the grid arrangement is Rexroth-specific and adapted for use on the training system. Notes 09 . Fig. 09.07 Connection block Measuring glass Component arrangement D Note: In the case of connection elements marked with “D”. the components can be connected directly with each other. risks of injury and a safety risk can arise during operation of the system.2 by means of hoses. Leakage oil may drip through open connections and cause a slipping risk. or that the connections are plugged by means of plug screws or protective caps.Project 09: Throttle valve. . Hydraulic systems can store pressure energy when at rest. Marking with a point for the precise adjustment (1st position). Connect the hydraulic control according to hydraulic circuit diagram Fig.e. 2. By actuating push-button S1 solenoid Y1b of 4/3 directional valve Item 1.2 to 50 bar plus one turn.1 in a clearly arranged form on the training system according to the prepared circuit diagram. Then open the throttle valve by � turn of the adjustment knob.4 are to be connected. Mount the components required according to Table 09. 4. the hydraulic motor Item 1.in this case also to minimess lines. 09. Check on the system pressure gauge that the system is depressurized. check that the electrical ON/ OFF switch on the hydraulic power unit is pressed in. Before commissioning the hydraulic control. For connections. and consequently to allow the recognition of potential risks.1 is energized. Close throttle valve Item 1. Warning Caution If work on electrohydraulic components is carried out improperly. i.3. that the system is switched off. Throttling process 1: 5.e. 09. Relevant sources of regulations are given in the introduction of the present manual. check. 09 Execution of the order Set up the control as described below: 1. It can cause injury when the system is opened. Set the system pressure on pressure relief valve Item 1. whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open. i.3.07 Safety notes To ensure the operability of plant and machinery. safety regulations must be observed before and during the execution of the order. Switch the hydraulic pump on and inspect the set up control for leakage. use hydraulic hoses DZ 25. to which pressure gauges with minimess line DZ 1. adjustable  Bosch Rexroth AG I RE 00845/04.0 rotates. 3. before switching the hydraulic pump on. Hand-tighten the pressure gauge measuring lines at the relevant minimess connection of the hydraulic hose. including danger to life. No pressure gauge may indicate a pressure. Wire the electrical control according to wiring diagram Fig. The correct and proper fit of the component connections with hoses can be checked by slightly turning the hoses. Warning Caution Make sure that pipes or hoses are connected to all connections . Before starting work on the training system. 35 bar.3 using pressure gauges M2 and M3 and enter the values in Table 09. � turn opened (2nd position).40 5.3.M3 ∆p in bar q in l/min 20 25 30 35 40 50 46 46 47 47 47 48 26 21 17 12 7 2 1. Measure the pressure differential ∆p across throttle valve Item 1.2. Throttle valve Item 1. 6.71 0 20 25 30 35 40 50 39 41 43 44 45 48 19 16 13 9 5 2 6. switch the hydraulic pump off! Open the throttle valve and set the pressure relief valves to minimum pressure.3 2nd position Throttle Item 1. Throttle valve Item 1.26 1. Caution After having completed practical work on the training system. Throttling process 2: 8.1. 30 bar.98 1.77 2.2.82 5.M3 ∆p in bar q in l/min M3 p in bar M2 p in bar M2 .4. Throttling process 3: 9.5. 40 bar and 42 bar. While the throttle position remains unchanged (1st position) increase the load pressure to 25 bar.2.M3 ∆p in bar q in l/min M3 p in bar M2 p in bar M2 .Project 09: Throttle valve.07 While directional valve Y1b is operated. Measured values Throttle Item 1. No pressure gauge may indicate a pressure! 10. which is installed in the return line of the 4/3 directional valve.87 0 20 25 30 35 40 50 44 45 45 46 47 48 24 20 15 11 7 2 3.18 0 Table 09. Follow the instructions in points 6 and 7 and enter the measurement result in Table 09.3.20 3.22 2.74 1. Optional: Carry the measured values over in a Diagram 09. adjustable  Bosch Rexroth AG I RE 00845/04.3 3rd position M3 p in bar M2 p in bar M2 . the load pressure can be adjusted to 20 bar on pressure relief valve Item 1.47 1.2 Measurement results from execution of the order 09 . The flow measurement can be taken with the help of a measuring glass in liters/time or optionally using flowmeter Item 1. 7.09 4.3 1st position Throttle Item 1.20 0. 1� turns opened (3rd position). Follow the instructions in points 6 to 8 and enter the values in Table 09. and the pressure value read off from pressure gauge M3.64 3. • At a constant flow the differential pressure becomes greater. .07 The values were measured at an oil temperature of approx. • At a constant differential pressure. • As the flow increases the differential pressure ∆p rises when the throttling cross-section remains constant.1 Diagram with measured values Evaluating the work results with regard to the customer requirement • The customer requirement can be met by means of a throttle valve. the flow is independent of the pressure level. the smaller the throttling crosssection is. 20 °C. The values measured by the trainees can deviate by 10 %. Since the throttle operates in dependence upon loads. adjustable 10 Bosch Rexroth AG I RE 00845/04. • As an optional extra. the customer wishes to implement a velocity adjustment feature for various weights. the velocity of the conveyor belt becomes smaller as the load increases (greater weight). 1st position 2nd position 3rd position Differential pressure ∆p in bar 30 25 20 15 10 5 09 0 0 1 2 3 4 5 6 7 Flow qV in l/min Diagram 09.Project 09: Throttle valve. meter-in or meter-out throttling can be provided. Notes on detailed technical information about the throttle check valve: • The Hydraulic Trainer Volume 1/Bosch Rexroth AG Basic principles and components. If the traversing speed is to be adjustable in only one direction. The task of a throttle check valve is to throttle a given flow in only one direction of rotation. a throttle valve can be used. type Z2FS 10 . By installing the throttle valve differently. on a single-rod cylinder.07 Project 10: Throttle check valve Project/trainer information If a given velocity is to be adjustable. Chapter 13 • Technical data sheet RE 27219/throttle check valve. the trainee can recognize the pros and cons of meter-in and meter-out throttling by taking measurements on the piston and on the piston rod side. • in the case of meter-out throttling the single-rod cylinder is hydraulically isolated.Project 10: Throttle check valve  Bosch Rexroth AG I RE 00845/04. If the throttle is used. The actuator to be controlled moves with flow throttling in one direction and almost unthrottled in the opposite direction. type MK Technical data sheet RE 27506/double throttle check valve. the trainee is to get familiar with the typical characteristics of a meter-in or meter-out throttle. Like a throttle valve a throttle check valve is a variable throttle with the disadvantages dealt with in Project 09 such as temperature and dependence on the differential pressure. In the project order. On the basis of the control set up on the training system for powering a horizontally installed single-rod cylinder. but pressure intensification can occur on the piston rod side. In the following Project 10 knowledge of the operating principle and the use of a throttle check valve can be imparted. he/she is to understand that: • a throttle check valve is a combination of a throttle and a check valve • with a throttle check valve the piston velocity of a single-rod cylinder can be adjusted in only one direction. a throttle check valve is used. • the use of a meter-in throttle can result in jerky movements of the single-rod cylinder (slip stick). for example. 1 Practical example: Tool advance for roll seam bending Project tasks • Independent understanding and solving of the task set by applying hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet of a throttle check valve (specialist qualification) • Handling of hydraulic components in line with functional needs . The return stroke is to be performed at maximum velocity. 10. In addition. As in Project 09.07 Project definition In a machining station (bending of a roll seam) the hydraulic advance velocity is to be adjustable.Project 10: Throttle check valve  Bosch Rexroth AG I RE 00845/04. measurements of meter-in and meter-out throttling are required. the customer requires technical documentation in order to be able to understand the proposed solution. 10 Fig. Working out and documenting the system parameters required by the customer. among others. through discussions with the customer.07 Project steps • Informing: Accepting and understanding the order. • Deciding: Preparation of a schematic diagram sketch and selection of components. • Planning: Planning and organizing the customer order with the help of. among others.Project 10: Throttle check valve  Bosch Rexroth AG I RE 00845/04. the technical data sheets RE 27219 and RE 27506. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? 10 Notes . • Executing: Set-up of the hydraulic control on the training system. 2 Power unit limit Fig.3 Item 1.Project 10: Throttle check valve  Bosch Rexroth AG I RE 00845/04.2 Hydraulic circuit diagram: Meter-in throttle .1 Item 1.07 Hydraulic circuit diagram 1 Item 1.extending a single-rod cylinder Measuring glass .0 Item 0. 10.2 Item 0.1 10 Item 0.3 Item 1. 07 Hydraulic circuit diagram 2 Item 1.1 Item 1.2 Item 0.1 10 Item 0. 10.2 Power unit limit Fig.Project 10: Throttle check valve  Bosch Rexroth AG I RE 00845/04.3 Hydraulic circuit diagram: Meter-out throttle .0 Item 0.3 Item 1.extending a single-rod cylinder Measuring glass .3 Item 1. 07 Hydraulic circuit diagram 3 Item 1.retracting a single-rod cylinder Measuring glass .1 10 Item 0.1 Item 1.2 Power unit limit Fig. 10.Project 10: Throttle check valve  Bosch Rexroth AG I RE 00845/04.4 Hydraulic circuit diagram: Meter-in throttle .3 Item 1.2 Item 0.0 Item 0.3 Item 1. 2 Power unit limit Fig.5 Hydraulic circuit diagram: Meter-out throttle .Project 10: Throttle check valve  Bosch Rexroth AG I RE 00845/04.retracting a single-rod cylinder Measuring glass . 10.3 Item 1.3 Item 1.0 Item 0.1 10 Item 0.07 Hydraulic circuit diagram 4 Item 1.1 Item 1.2 Item 0. Project 10: Throttle check valve  Bosch Rexroth AG I RE 00845/04.07 Electrical circuit diagram Stop 10 Control 4/3 directional valve Fig.2 to 10. 10. 10.5 Retraction Extension -Single-rod cylinder- .6 Wiring diagram for hydraulic schematic diagrams Fig. B DW 13E 1.0.1 Parts list for hydraulic circuit diagrams 10.3 1 Throttle check valve.1 1 4/3 directional valve with direct actuation by two solenoids.3 10 0.5 . adjustable.4 3 Hose with quick release coupling with check valve DZ 25 Hose VSK 1 Table 10. A.0 1 Double-acting cylinder with single-sided piston rod 1.2 1 Direct operated pressure relief valve.1 1.1 . spring centering of the central position and central position P. T.2 Symbol ZY 1.3 1 Distributor plate with four ports DZ 4.Project 10: Throttle check valve  Bosch Rexroth AG I RE 00845/04. the cracking pressure can be adjusted by means of a spring DD 1.07 Component selection with parts list Item Qty Component designation Type designation 1.2 to 10. free flow in one direction DF 2.1 3 Pressure gauge with hose and quick release coupling without check valve DZ 1. 7 Recommended component arrangement with component designation for parts list Table 10. Notes 10 .1 and hydraulic circuit diagram 10. Also the grid arrangement is Rexroth-specific and adapted for use on the training system.Project 10: Throttle check valve 10 Bosch Rexroth AG I RE 00845/04.2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. Fig.07 Connection block Measuring glass Component arrangement 1 D Note: In the case of connection elements marked with “D”. 10. the components can be connected directly with each other. Notes 10 .1 and hydraulic circuit diagram Fig.8 Recommended component arrangement with component designation for parts list Table 10. 10.07 Connection block Measuring glass Component arrangement 2 D Note: In the case of connection elements marked with “D”.3 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. the components can be connected directly with each other.Project 10: Throttle check valve 11 Bosch Rexroth AG I RE 00845/04. Fig. Also the grid arrangement is Rexroth-specific and adapted for use on the training system. 10. 9 Recommended component arrangement with component designation for parts list Table 10. Notes 10 . 10.1 and hydraulic circuit diagram Fig. the components can be connected directly with each other.Project 10: Throttle check valve 12 Bosch Rexroth AG I RE 00845/04.4 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. 10.07 Connection block Measuring glass Component arrangement 3 D Note: In the case of connection elements marked with “D”. Also the grid arrangement is Rexroth-specific and adapted for use on the training system. Fig. Notes 10 . Fig. Also the grid arrangement is Rexroth-specific and adapted for use on the training system.1 and hydraulic circuit diagram 10.5 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations.07 Measuring glass Component arrangement 4 Connection block ������ D Note: In the case of connection elements marked with “D”.10 Recommended component arrangement with component designation for parts list Table 10.Project 10: Throttle check valve 13 Bosch Rexroth AG I RE 00845/04. the components can be connected directly with each other. 10. Mount the components required according to Table 10. 10 . Leakage oil can drop through open ports on the floor and cause a risk of slipping. that the system is switched off. check. use hydraulic hoses DZ 25. Execution of the order Set up the controls as described in the following: 1. Warning Caution If work on electrohydraulic components is carried out improperly. 10.in this case also minimess lines . Before commissioning the hydraulic control. whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open.pipes and hoses are connected or that the ports are blocked with plug screws or protective caps. Set the system pressure on pressure relief valve Item 1. Enter the pressure values (during extending) on piston side M2 and on piston rod side M3 in Table 10. 10. Hydraulic systems can store pressure energy when at rest. including danger to life. The correct and proper fit of the component connections with hoses can be checked by slightly turning the hoses. to this end operate push-button S2.6. Wire the electrical control according to wiring diagram Fig.e. Task 1 Meter-in throttle: Piston side → extending 4. Hand-tighten the pressure gauge measuring lines at the relevant minimess connection of the hydraulic hose. Check on the system pressure gauge that the system is depressurized. Switch the hydraulic pump on and inspect the set up control for leakage.2 to 50 bar plus one turn. check that the electrical ON/ OFF switch on the hydraulic power unit is pressed in. Relevant sources of regulations are given in the introduction of the present manual. Connect the hydraulic control according to hydraulic circuit diagram Fig.2 by means of hoses. Before starting work on the training system. safety regulations must be observed before and during the execution of the order. risks of injury and a safety risk can arise during operation of the system. It can cause injury when the system is opened.2. to which pressure gauges with minimess line DZ 1. Adjust throttle check valve Item 1.07 Safety notes To ensure the operability of plant and machinery.3 so that the piston of the single-rod cylinder extends within 5 s. and consequently to allow the recognition of potential risks. No pressure gauge may indicate a pressure. i. i.4 are to be connected. 2.e. 3. For connections.1 in a clearly arranged form on the training system according to the prepared circuit diagram.Project 10: Throttle check valve 14 Bosch Rexroth AG I RE 00845/04. before switching the hydraulic pump on. Warning Caution Make sure that all ports . 5. observing the safety notes given under point 1. 10.3.Project 10: Throttle check valve 15 Bosch Rexroth AG I RE 00845/04. Enter the pressure values (during retracting) on piston side M2 and on piston rod side M3 in Table 10. 8.3 so that the piston of the single-rod cylinder extends within 5 s. observing the safety notes given under point 1.2. 10. Enter the pressure values (during retracting) on piston side M2 and on piston rod side M3 in the table of measured values. Convert the hydraulic control according to Hydraulic circuit diagram Fig. Adjust throttle check valve Item 1. observing the safety notes given under point 1. Adjust throttle check valve Item 1. switch the hydraulic pump off! No pressure gauge may indicate a pressure! Caution Task 3 Meter-out throttle: Piston rod side ← retracting 7. Convert the hydraulic control according to Hydraulic circuit diagram Fig. Caution After having completed practical work on the training system switch the hydraulic pump off! No pressure gauge may indicate a pressure! Open the throttle check valve.4. To this end first operate push-button S2 for extending and then for the adjustment of the throttle operate push-button S4 for retracting. switch the hydraulic pump off! No pressure gauge may indicate a pressure! Caution Task 2 Meter-out throttle: Piston rod side → extending 5. Adjust throttle check valve Item 1. 10. Repeat working steps 2 to 4. Enter the pressure values (during extending) on piston side M2 and on piston rod side M3 in Table 10.3 so that the piston of the single-rod cylinder retracts within 5 s. To this end actuate push-button S2.07 Before making any conversion for further order processing. To this end first operate push-button S2 for extending and then for the adjustment of the throttle operate push-button S4 for retracting.2. Before making any conversion for further order processing. switch the hydraulic pump off! No pressure gauge may indicate a pressure! Caution Task 4 Meter-out throttle: Piston side ← retracting 9. 6.3 so that the piston of the single-rod cylinder retracts within 5 s. 10. Before making any conversion for further order processing. Repeat working steps 2 and 3. Convert the hydraulic control according to Hydraulic circuit diagram Fig. 10 . Repeat working steps 2 and 3. • A throttle check valve is a combination of devices comprising a throttle valve and a check valve. protection must be provided in the form of an additional pressure relief valve. • The flow through a throttle check valve depends on the differential pressure ∆p. Warning Safety note from accident prevention regulations: If there is a riks of pressure intensification on the piston rod side. 20 °C. which is the double system pressure. e. piston rod side ← retracting 2 4 Meter-out throttle. the system operator must secure the setting against unauthorized changes by providing a lead seal. Setting: 10 % above system pressure. • To provide protection against pressure intensification a pressure relief valve can be installed. • The advance cylinder can be hydraulically isolated during extended. but on the piston rod side there is a risk of pressure intensification. The values measured by the trainees can deviate by 10 %. piston side → extending 2 3 Meter-out throttle. i.07 Measured values M2 p in bar M3 p in bar Meter-in throttle. 2 : 1.2 Measurement results from the execution of the order The measurement results were obtained at an oil temperature of approx.g. Depending on the area ratio of the single-rod cylinder the intensified pressure can reach. piston rod side → extending 50 77 Meter-in throttle. 10 . Evaluating the work results with regard to the customer requirement • The customer requirement can be met by means of a throttle check valve.e. the traversing speed of the advance carriage is adjustable in one direction. piston side ← retracting 27 50 Measuring points → Table 10.Project 10: Throttle check valve 16 Bosch Rexroth AG I RE 00845/04. drops below a minimum pressure differential. • a flow control valve features a closed hydraulic control loop. Notes on the detailed technical information about the flow control valve: • The Hydraulic Trainer Volume 1/Bosch Rexroth AG Basic principles and components. the flow remains constant. In the following Project 11 you can impart knowledge of the operating principle and use of flow control valves. A flow control valve comprises a control loop and consists of an adjustable orifice and an upstream or downstream pressure compensator.07 Project 11: Flow control valve Project/trainer information If the velocity of a hydraulic cylinder or the speed of a hydraulic motor is to be kept constant independently of pressure fluctuations. chapter 13 • Technical data sheet RE 28163/2-way flow control valve 11 . a flow control valve is used. The task of the flow control valve used is to maintain the speed of a hydraulic motor constant despite varying loads. which is to lift and lower different loads. • flow qV eff. the trainee can recognize the different flow rates under changing loads. the trainee has to work out and record the characteristic curves of a 2-way flow control valve. he/she is to recognize that: • the flow remains constant at varying load pressures. e. The load can be simulated with the help of a pressure relief valve installed in the return line of the 4/3 directional valve. but is to move at the same traversing velocity. By making various adjustments to the flow control valve and changing the loads on the hydraulic motor. the set flow is kept constant. In the project order.Project 11: Flow control valve  Bosch Rexroth AG I RE 00845/04. With the help of the control set up on the training system for driving a hydraulic motor. Due to a continuous comparison of the pressures upstream and downstream of the adjustable orifice. in conjunction with a hydraulic cylinder.g. • at varying inlet pressures. Applying the knowledge that was gained in Project 09. a load-independent throttle valve is to be used in the velocity control. 11. the motor speed must remain constant. 11 Fig. a flow/pressure differential curve for varying loads and falling system pressures. In order that the customer can understand the solution. a hydraulic rotary drive is to swivel a drum from the horizontal to the vertical position after a welding process. Despite varying loads. he requires. apart from the technical documentation for the use of different workpiece weights.07 Project definition In a machining station.1 Practical example: Rotary drive for workpiece relocation Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet for a flow control valve (technical qualification) • Handling of hydraulic components in line with functional needs .Project 11: Flow control valve  Bosch Rexroth AG I RE 00845/04. The movement is to be performed by a hydraulic motor. among others.Project 11: Flow control valve  Bosch Rexroth AG I RE 00845/04. • Executing: Set-up of the hydraulic control on the training system and preparation and documentation of the system parameters requested by the customer. • Deciding: Using the sketches of the circuit diagrams from Project 10: Throttle check valve. by dealing intensively with data sheet RE 28163. among others.07 Project steps Notes • Informing: Accepting and understanding the order. through discussions with the customer. selection of the relevant sketch with selection of the hydraulic components. • Planning: Planning and organizing the execution of the customer order. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? 11 . 4 Load pressure 11 Item 0.2 Power unit limit Fig.4 Item 1.1 Item 0.0 Item 1. 11.2 Hydraulic circuit diagram: Load-independent speed control of a tool spindle Measuring glass .07 Hydraulic circuit diagram Item 0.3 Item 1.1 Item 1.3 Item 1.Project 11: Flow control valve  Bosch Rexroth AG I RE 00845/04.2 Item 0. 11.2 Rotation Rotation -Hydraulic motor- .3 Wiring diagram for hydraulic circuit diagram Fig. 11.07 Electrical circuit diagram Stop 11 Control 4/3 directional valve Fig.Project 11: Flow control valve  Bosch Rexroth AG I RE 00845/04. N 1. for one direction of flow. adjustable.4 2 Direct operated pressure relief valve. B DW 13E 1. T.4 11 4 Pressure gauge with hose and quick-release coupling. the cracking pressure can be adjusted by means of a spring DD 1. largely independent of viscosity and pressure diferential.Project 11: Flow control valve  Bosch Rexroth AG I RE 00845/04. with by-pass check valve DF 3 1.1 1 2-way flow control valve.1 Hose 1 Stopwatch Table 11. spring centring of the central position and central position P.0 1 Fixed displacement motor with external leakage line and two directions of rotation DM 2.2/1.2 Symbol VSK 1 .0. A.3 0. adjustable. with check valve DZ 25.1 . without check valve DZ 1.07 Component selection with parts list Item Qty Component designation Type designation 1.1 1 4/3 directional valve direct operated by two solenoids.4 4 Hose with quick-release coupling.1 Parts list for hydraulic circuit diagram 11. 11.2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations.07 Connection block Measuring glass Component arrangement D Note: In the case of connection elements marked with “D”.4 Recommended component arrangement with component designations to parts list Table 11. Fig. 11. the components can be connected directly with each other. Notes 11 .1 and hydraulic circuit diagram Fig. Also the grid layout is Rexroth-specific and adapated for use on the training system.Project 11: Flow control valve  Bosch Rexroth AG I RE 00845/04. safety regulations must be observed before and during the execution of the order. and consequently to allow the recognition of potential risks.3 to scale position 2. whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open.3. Calculate the pressure differential Dp (M2 . 2. Enter the pressure values M2 (upstream of DF 3) and M3 (downstream of DF 3) in measurement table 11. or that the connections are plugged by means of plug screws or protective caps.2 by means of hoses. Turn flow control valve item 1. the hydraulic motor rotates clockwise. 5. Execution of the order Set up the controls as described below: 1. use hydraulic hoses DZ 25. that the system is switched off. to which pressure gauges with minimess line DZ 1. 11.e. The proper and tight fit of hose connections of components can be easily checked by slightly turning the hoses.5 in the return flow line to 10 bar (pressure gauge M4). including danger to life. Warning Caution Before starting work on the training stand. Relevant sources of regulations are given in the introduction of the present manual. Connect the hydraulic control according to hydraulic circuit diagram Fig. 4. Hand-tighten the pressure gauge measuring lines hand tight at the relevant minimess connection of the hydraulic hose.2. No pressure gauge may indicate a pressure. make sure that electrical ON/OFF switches on the hydraulic power unit are pressed in. risks of injury and a safety risk can arise during operation of the system. Hang the components required according to Table 11.M3) and enter it in the measurement table. This can cause injury when the system is opened. Switch the hydraulic pump on and inspect the set up control for leakage. 11. Operate pushbutton S4.in this case also to minimess lines. Set the system pressure on pressure relief valve item 1. before switching the hydraulic pump on. Task 1 Determining the flow/pressure differential curve with rising load pressure 3. For connections. 11 . adjust the load pressure on pressure relief valve item 1. Leakage oil may drip through open connections and cause a slipping risk. If work on electrohydraulic components is carried out improperly.1 in a clearly arranged manner into the training system according to the prepared circuit diagram.4 are to be connected. Warning Caution Make sure that pipes or hoses are connected to all connections .2 to 45 bar. Before commissioning the hydraulic control. Wire the electrical control according to wiring diagram Fig.Project 11: Flow control valve  Bosch Rexroth AG I RE 00845/04. i. Hydraulic systems can store pressure energy at rest. check.07 Safety notes To ensure the operability of plant and machinery. Check on the system pressure gauge that the system is depressurized.1. that is. 90 42 40 25 17 15 0.3 to scale position 4. Scale position 2 Scale position 4 2.47 1.5 in the return flow line to 40 bar and enter the pressure values M2. 7.47 1.86 42 40 35 7 5 0. 8. Stepwise increase (in 5 bar increments) the load pressure on the hydraulic motor by means of pressure relief valve item 1.46 1. Measured values Measuring point M2 p in bar M3 p in bar Pressure differential Dp in bar Flow qV in l/min Scale position 2 Scale position 4 Load pressure Scale position 2 Scale osition 4 Scale position 2 Scale position 4 42 40 10 32 30 0.30 42 42 40 2 2 0 0 11 Table 11.5 Flow qV in l/min 2 1.Project 11: Flow control valve  Bosch Rexroth AG I RE 00845/04. increasing load pressure The values were measured at an oil temperature of approx.46 1.31 1. Repeat order steps 5 to 6 and enter the measured values in Table 11.07 Flow measurement by means of the measuring glass as a function of time or optionally using flowmeter DZ 30.45 1. M3.2 Values measured during the execution of the order.2.1. increasing load pressure 30 35 40 . the Dp and flow qV in Table 11. Turn flow control valve item 1.5 0 0 5 10 15 20 25 Pressure differential Dp in bar Diagram 11.5 1 0.90 42 40 30 12 10 0.1 Flow/pressure differential curve.92 42 40 20 22 20 0.92 42 40 15 27 25 0. 6. The values measured by trainees can deviate by 10 %. 20 °C. The values measured by trainees can deviate by 10 %. the hydraulic motor rotates clockwise. Operate pushbutton S4. Enter flow qV in Table 11.3 to scale position 2.2 down to the minimum pressure of 10 bar.3. 11 . 11. Turn flow control valve item 1.5 35 5 30 0. Set pressure relief valve item 1.3.5 30 5 35 0. No pressure gauge may indicate a pressure! Measured values Measuring point M1 Measuring point M3 Pressure differential p in bar p in bar Dp in bar Flow qV in l/min 40 5 35 0.3 Falling system pressure The results above were measured at an oil temperature of approx. switch the hydraulic pump off! Set the throttle valve and pressure relief valves to minimum pressure. Caution After completion of the practical work on the training system. Set the system pressure on pressure relief valve item 1.2 to 40 bar. 12. Calculate the pressure differential Dp (M1 .5 25 5 20 0.07 Determining the flow/pressure differential curve at varying system pressure 9.5 20 5 15 0.5 15 5 10 0. Flow measurement by means of the measuring glass or optionally by means of flowmeter DZ 30.M3) and enter the value in the measurement table. 10. Stepwise reduce (in 5 bar increments) the system pressure by means of pressure relief valve item 1. 20 °C.4 Table 11. Enter pressure values M1 (upstream of DW 13E) and M3 (downstream of DF3) in Table 11.5 in the return flow line (load pressure) to minimum (spring unloaded).Project 11: Flow control valve Task 2 10 Bosch Rexroth AG I RE 00845/04. 13.5 10 5 5 0. the flow control valve features a closed hydraulic control loop.1 0 0 10 15 20 25 30 35 40 Pressure differential ∆p in bar Diagram 11.5 0. flow qV remains largely constant. • In terms of construction.2 Flow/pressure differential curves. system pressure falling 11 Evaluating the work results with regard to the customer requirement • At a varying load pressure. which creates a constant ∆p across the orifice.Project 11: Flow control valve 11 Bosch Rexroth AG I RE 00845/04. • Below a minimum pressure differential (manufacturer-specific) flow qV drops.3 0. flow qV remains largely constant.4 0. the flow control valve consists of an adjustable orifice and a pressure compensator.07 0.2 0.6 Flow qV in l/min 0. • At varying inlet/system pressure. . 07 Notes 11 .Project 11: Flow control valve 12 Bosch Rexroth AG I RE 00845/04. In the following Project 12 knowledge of the operating principle. • despite an open pressure relief valve a resistance (line and valve resistance) can be observed. Pressure relief valves are used to limit the system pressure of a hydraulic control. connections. By making various settings on the pressure relief valve. In the special machinery construction sector. Chapter 12 • Technical data sheet RE 25402/Pressure relief valve. Pressure relief valves are also used to provide protection against. The resistance is provided by an adjustable throttle valve. for example. We differentiate pressure relief valve by: Pressure relief valves.g. To be able to assess the characteristics of a direct operated pressure relief valve. in presses. direct operated Project/trainer information If the operating pressure/system pressure is to be limited to an adjustable maximum value in a hydraulic system. direct operated 12 . In the project order. direct operated  Bosch Rexroth AG I RE 00845/04. the trainee is to get to know the characteristic curves of a direct operated pressure relief valve. On the basis of the set up control the trainee can work out the characteristic curves of a pressure relief valve by changing the system pressure and the resistance installed in parallel. a pressure relief valve is used. control blocks.Project 12: Pressure relief valve. the characteristic curves of the pressure/flow relation must be known. etc. against destruction. Notes on detailed technical information about the direct operated pressure relief valve: • The Hydraulic Trainer Volume 1/Bosch Rexroth AG Basic principles and components. e. use and adjustment options of direct operated pressure relief valves is to be gained. as overload protection. • in the case of a parallel connection of throttle and pressure relief valves the flow is divided. pressure relief valves are also used as load holding valves. direct operated and pilot operated.g. The limitation of the system pressure protects system components such as pipes and hoses. pump housings.07 Project 12: Pressure relief valve. • pressure relief valves can be used. he/she is to recognize that: • the characteristic curve of a pressure relief valve shows the dependence of pressure p on flow qV. pressure peaks. e. Project 12: Pressure relief valve.1 Practical example: Pressure relief valves Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet of a pressure relief valve (specialist qualification) • Handling of hydraulic components in line with functional needs . he is interested in the pressure/flow relationship characteristic curves of pressure relief valves. The new setting is to save energy. direct operated  Bosch Rexroth AG I RE 00845/04. the system pressure is to be reduced due to the use of lower weights. 12. The customer requires work instructions in order that he can adjust the pressure without requiring expert help. 12 Fig.07 Project definition On a lifting platform. Moreover. direct operated  Bosch Rexroth AG I RE 00845/04. among others. • Executing: Set-up of the hydraulic control on the training system. Working out and documenting the system parameters required by the customer. by dealing intensively with technical data sheets RE 25402. • Deciding: Preparation of a schematic diagram sketch and selection of components.07 Project steps • Informing: Accepting and understanding the order. • Planning: Planning and organizing the customer order. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? Notes 12 . through discussions with the customer.Project 12: Pressure relief valve. among others. 1 Item 1. direct operated Measuring glass 12 .Project 12: Pressure relief valve.07 Hydraulic circuit diagram Item 1. 12.2 Hydraulic circuit diagram: Determination of technical data of a pressure relief valve.5 Item 0.0 Power unit limit Fig. direct operated  Bosch Rexroth AG I RE 00845/04.1 Item 1. 1 1 Pressure gauge with hose and quick release coupling without check valve DZ 1.1 Parts list for hydraulic circuit diagram Fig. direct operated  Bosch Rexroth AG I RE 00845/04.0 1 Direct operated pressure relief valve. 12.2 1 Distributor plate with four ports DZ 4.07 Component selection with parts list Item Qty Component designation Type designation 1. the cracking pressure can be adjusted by means of a spring DD 1.4 1 Hose with quick release coupling with check valve DZ 25 Hose VSK 1 0.1 1 Throttle valve.Project 12: Pressure relief valve.1 1 Stopwatch 1 Flowmeter Table 12. adjustable DF 1.2 DZ 30 Symbol 12 .1 1. 12. the components can be connected directly with each other.2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations.3 Recommended component arrangement with component designation for parts list Table 12. 12. direct operated  Bosch Rexroth AG I RE 00845/04.Project 12: Pressure relief valve.07 Connection block Measuring glass Component arrangement D Note: In the case of connection elements marked with “D”.1 and hydraulic circuit diagram Fig. Also the grid arrangement is Rexroth-specific and adapted for use on the training system. Fig. Notes 12 . whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open. The correct and proper fit of the component connections with hoses can be checked by slightly turning the hoses. Before starting work on the training system. 12 .0. No pressure gauge may indicate a pressure. set the system pressure to 30 bar on pressure relief valve Item 1. Warning Caution If work on electrohydraulic components is carried out improperly. use hydraulic hoses DZ 25. including danger to life. Warning Caution Make sure that pipes or hoses are connected to all connections . Execution of the order Set up the control as described below: 1. before switching the hydraulic pump on. Before commissioning the hydraulic control.2 by means of hoses.2 (DZ 30). It can cause injury when the system is opened. Mount the components required according to the parts list in a clearly arranged form on the training system according to the prepared circuit diagram. Relationship between flow and pressure relief valve 2.4 are to be connected. check. Switch the hydraulic pump on and inspect the set up control for leakage. Measure the flow through the measuring glass as a function of time or optionally using flowmeter Item 1.in this case also to minimess lines. 12. Hand-tighten the pressure gauge measuring lines at the relevant minimess connection of the hydraulic hose. that the system is switched off. safety regulations must be observed before and during the execution of the order. to which pressure gauges with minimess line DZ 1.1.2. Check on the system pressure gauge that the system is depressurized. i. An electrical control is not required for this experiment set-up.e. 3. Leakage oil may drip through open connections and cause a slipping risk. Close throttle valve Item 1. For connections. i.Project 12: Pressure relief valve.e. Enter the values in Table 12.07 Safety notes To ensure the operability of plant and machinery. and consequently to allow the recognition of potential risks. Connect the hydraulic control according to hydraulic circuit diagram Fig. Relevant sources of regulations are given in the introduction of the present manual. Hydraulic systems can store pressure energy when at rest. check that the electrical ON/ OFF switch on the hydraulic power unit is pressed in. direct operated  Bosch Rexroth AG I RE 00845/04. risks of injury and a safety risk can arise during operation of the system. or that the connections are plugged by means of plug screws or protective caps. direct operated  Bosch Rexroth AG I RE 00845/04. Open throttle valve Item 1.3 20 1.1. 12 .2.pressure/flow The values were measured at an oil temperature of approx.6 25 4. 20 °C.8 15 0 10 0 Open Table 12.2 to Diagram 12. Enter the M1 measurement results and flow qV in Table 11. After having completed practical work on the training system switch the hydraulic pump off! No pressure gauge may indicate a pressure! Open the throttle check valve.1 in individual steps (5 bar increments).Project 12: Pressure relief valve. The pressure is shown on pressure gauge M1. The values measured by the trainees can deviate by 10 %.2 Measured values: Pressure relief valve . Carry over the measurement results from Table 12. 5. Caution Measured values Throttle valve System pressure M1 p in bar Flow qV in l/min through pressure relief valve Closed 30 7.07 4. • When the throttle valve is open or the pressure relief valve is open. 12 . • Pressure relief valves are mainly used as overload protection for limiting the maximum pressure. falling system pressure Evaluating the work results with regard to the customer requirement • The characteristic curve of the pressure relief valve shows the dependence of pressure p on flow qV. a resistance can be measured. which can be traced back to line resistances and the valve resistance. • Due to the interaction of the throttle valve and the pressure relief valve the flow is divided. direct operated  Bosch Rexroth AG I RE 00845/04.Project 12: Pressure relief valve.07 35 System pressure M1 p in bar 30 25 20 15 10 5 0 0 1 2 3 4 5 6 7 8 Flow qV across the pressure relief valve in l/min Diagram 12.1 Pressure/flow characteristic curves. Project 12: Pressure relief valve. direct operated 10 Bosch Rexroth AG I RE 00845/04.07 Notes 12 . chapter 12 • Technical data sheet RE 25402/Pressure relief valve. the trainee has to become familiar with the theoretical principles of the circuits. • in the case of pressure relief valves controlled in parallel. With the help of a 4/3 directional valve he/she can control pressure relief valves optionally connected in parallel or in series. the pressures add up. the trainee has to develop and record the adjustment options of parallel and series circuits with the help of experiment set-ups on the training system. the lowest set pressure becomes effective. the trainee is to understand the typical features of the controls by operating pressure relief valves connected in parallel and in series.Project 13: Pressure relief valve control  Bosch Rexroth AG I RE 00845/04. In the project order. he/she is to recognize that: • Pressure relief valves can be used for pre-selecting various system and pilot pressures via pressure stage circuits.07 Project 13: Pressure relief valve control Project/trainer information If three different pressures are to be realized in a hydraulic circuit. As preparation to the practical experiment. The following Project 13 can be used to acquire knowledge of the practical use and adjustment options of direct operated pressure relief valves. Notes on the detailed technical information about the direct operated pressure relief valve: • The Hydraulic Trainer Volume 1/Bosch Rexroth AG Basic principles and components. • in the case of pressure relief valves controlled in series. By controlling the pressure relief valves in different ways by means of a 4/3 directional valve. With the help of the controls set up on the training system. direct operated 13 . pressure relief valves connected in series or in parallel can be used for this purpose. 1 Practical example: Punching equipment Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet for a pressure relief valve (technical qualification) • Handling of hydraulic components in line with functional needs . 13. electrically controllable pressures are to be callable for different tools and different working sequences.07 Project definition On a punching rig. 13 Fig. The customer wishes solution proposals for the simple realization of a pressure control and requires technical documentation with the necessary system parameters. three.Project 13: Pressure relief valve control  Bosch Rexroth AG I RE 00845/04. through discussions with the customer. • Planning: Planning and organizing the execution of the customer order. by dealing intensively with data sheet RE 25402.07 Project steps • Informing: Accepting and understanding the order.Project 13: Pressure relief valve control  Bosch Rexroth AG I RE 00845/04. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? Notes 13 . • Executing:: Preparation of a schematic circuit diagram and selection of the required drive elements and accessories with short description. • Deciding: Preparation of a circuit diagram sketch and selection of components. among others. among others. 07 Hydraulic circuit dagram 1 Item 0.0 Measuring glass Item 0.2 Hydraulic circuit diagram: 3-stage pressure circuit .3 Item 1.1 Item 1. 13.2 Item 0.Project 13: Pressure relief valve control  Bosch Rexroth AG I RE 00845/04.2 Item 1.1 13 System Power unit limit Fig. 1 Item 1.3 Hydraulic circuit diagram: Parallel pressure circuit .07 Hydraulic circuit diagram 2 Item 0. 13.Project 13: Pressure relief valve control  Bosch Rexroth AG I RE 00845/04.1 13 System Power unit limit Fig.3 Item 1.2 Item 1.0 Measuring glass Item 0.2 Item 0. 0 Measuring glass Item 0.4 Hydraulic circuit diagram: Series pressure circuit 13 .1 System Power unit limit Fig.Project 13: Pressure relief valve control  Bosch Rexroth AG I RE 00845/04.2 Item 0.1 Item 1.2 Item 1.07 Hydraulic circuit diagram 3 Item 0.3 Item 1. 13. 13.Project 13: Pressure relief valve control  Bosch Rexroth AG I RE 00845/04.07 Electrical circuit diagram Circulation 13 Control 4/3 directional valve Solenoid “a” Fig.4 Solenoid “b” . 13.2 and 13.5 Wiring diagram for hydraulic circuit diagrams Fig. 2 to 13. the cracking pressure can be adjusted by means of a spring DD 1.1/1.1 Parts list for hydraulic circuit diagrams Fig.4 3 Hose with quick-action coupling. B DW 4E 1.2 2 Direct operated pressure relief valve. spring centring of the central position and central position P .1 3 Pressure gauge with hose and quick-release coupling without check valve DZ 1. 13.Project 13: Pressure relief valve control  Bosch Rexroth AG I RE 00845/04.1 .3 Table 13.1 2 Distributor plate with four connections DZ 4.07 Component selection with parts list Item Qty Component designation Type designation 1. with check valve DZ 25 Hose VSK 1 0.0. A.T.0 1 4/3 directional valve with direct operated by two solenoids.4 Symbol 13 . 2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. the components can be connected directly with each other.1 and hydraulic circuit diagram Fig. Fig.07 Connection block Measuring glass Component arrangement 1 D Note: In the case of connection elements marked with “D”. Also the grid layout is Rexroth-specific and adapated for use on the training system.Project 13: Pressure relief valve control  Bosch Rexroth AG I RE 00845/04. 13. Notes 13 .6 Recommended component arrangement with component desgnations for parts list Table 13. 13. Project 13: Pressure relief valve control 10 Bosch Rexroth AG I RE 00845/04. Also the grid layout is Rexroth-specific and adapated for use on the training system. the components can be connected directly with each other.7 Recommended component arrangement with component designations for parts list Table 13. 13. Fig.1 and hydraulic circuit diagram Fig.3 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. 13. Notes 13 .07 Connection block Measuring glass Component arrangement 2 D Note: In the case of connection elements marked with “D”. Project 13: Pressure relief valve control 11 Bosch Rexroth AG I RE 00845/04. Notes 13 . Also the grid layout is Rexroth-specific and adapated for use on the training system.1 and hydraulic circuit diagram Fig.07 Connection block Measuring glass Component arrangement 3 D Note: In the case of connection elements marked with “D”. 13.8 Recommended component arrangement with component designations for parts list Table 13. Fig. the components can be connected directly with each other. 13.4 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. For the connections. Set the system pressure on pressure relief valve item 1. Hydraulic systems can store pressure energy at rest. i. that is. Hand-tighten the pressure gauge line hand tight to the relevant minimess connection of the hydraulic hose. safety regulations must be observed before and during the execution of the order. Switch the hydraulic pump and check the set up control for leakage. Before commissioning the hydraulic control.4 are to be connected. check. No pressure gauge may indicate a pressure. risks of injury and a safety risk can arise during operation of the system. Warning Caution Before starting work on the training stand. correct it to 50 bar.Project 13: Pressure relief valve control 12 Bosch Rexroth AG I RE 00845/04. Hang the components required according to the parts list in a clearly arranged manner into the training system according to the prepared circuit diagram. Check the pressure set on the control pump of the drive power unit and.in this case also to minimess lines or that the connections are plugged by means of plug screws or protective caps. make sure that electrical ON/OFF switches on the hydraulic power unit are pressed in. The proper and tight fit of hose connections of components can be easily checked by slightly turning the hoses. 3-stage pressure circuit 2. 3. use hydraulic hoses DZ 25. This can cause injury when the system is opened. Connect the hydraulic control according to hydraulic circuit diagram Fig. before switching the hydraulic pump on. Leakage oil may drip through open connections and cause a slipping risk. Relevant sources of regulations are given in the introduction of the present manual. If work on electrohydraulic components is carried out improperly. Warning Caution Task 1 Make sure that pipes or hoses are connected to all connections . Operate directional valve item 1. whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open.07 Safety notes To ensure the operability of plant and machinery. Check on the system pressure gauge that the system is depressurized. 13.e. that the system is switched off. including danger to life. to which the pressure gauges with minimess line DZ 1. if required. 13 .1 at port B to 15 bar (pressure gauge M2).5. and consequently to allow the recognition of potential risks. Wire the electrical control according to wiring diagram 13. Execution of the order Set up the control as described below: 1.2 by means of hoses.0 by actuating pushbutton S4. switch the hydraulic pump off! No pressure gauge may indicate a pressure! Caution Task 3 Series circuit 7.4 by means of hoses. Enter the measured values (pressure gauge M1. Before converting the circuit for the further execution of the order. switch the hydraulic pump off! No pressure may indicate a pressure! Open the throttle check valve.3.1 and item 1. Connect the hydraulic control according to circuit diagram Fig. Operate directional valve item 1. Operate directional valve item 1. 13.0 by actuating pushbutton S2. M3) in Table 13. Do not change the pressures set on pressure relief valves item 1.0 by actuating pushbutton S2. switch the hydraulic pump off! No pressure gauge may indicate a pressure! Caution Task 2 Parallel circuit 5. Set the system pressure on pressure relief valve item 1.07 4.Project 13: Pressure relief valve control 13 Bosch Rexroth AG I RE 00845/04.0 by actuating pushbutton S2. 13 .2 at port A to 20 bar (pressure gauge M3). Enter the measured values (pressure gauges M1 and M2) in Table 13. M2.2! 6. Connect the hydraulic control according to circuit diagram Fig.4. Caution Notes After completion of the practical work on the training system.3 by means of hoses. Operate directional valve item 1. M2.2! 8. Before converting the circuit for the further execution of the order. 13. M3) in Table 13.2. Do not change the pressures set on pressure relief valves item 1. Enter the measured values (pressure gauges M1.1 and item 1. direct operated pressure relief valves can be controlled via a directional valve and consequently three different.3 Parallel pressure circuit Spool position DW 4E Measuring point M1 Measuring point M2 Measuring point M3 p in bar p in bar p in bar 0 8 0 0 a 38 35 20 Table 13. The values measured by trainees can deviate by 10 %. Evaluating the work results with regard to the customer requirement • In a 3-stage pressure circuit.Project 13: Pressure relief valve control 14 Bosch Rexroth AG I RE 00845/04.4 Series pressure circuit The values were measured at an oil temperature of approx. the lowest pressure set is effective. 20 °C. 13 . • In the case of pressure relief valves connected in parallel. the set pressures add up.2 3-stage pressure circuit Spool position DW 4E Measuring point M1 p in bar Measuring point M2 p in bar 0 8 0 a 18 15 Table 13.07 Measured values Spool position DW 4E Measuring point M1 Measuring point M2 Measuring point M3 p in bar p in bar p in bar 0 8 0 0 a 23 0 20 b 18 15 0 Table 13. • In the case of pressure relief valves connected in series. pre-selected system pressures can be realized. Project 14: Pressure reducing valve  Bosch Rexroth AG I RE 00845/04. The task of a pressure reducing valve is to keep the output pressure constant and lower than the input pressure. • excess pressure in port A is discharged via port T of the pressure reducing valve to the tank. which limits the input pressure. In contrast to the pressure relief valve. In the project order the trainee is to get familiar with the typical characteristics of a pressure reducing valve with the help of a practice-oriented experiment set up on the training system. • a pressure reducing valve without by-pass check valve operates as pressure relief valve when controlled via port A. This project task is to help him/her understand that: • with the help of a pressure reducing valve a secondary actuator can be controlled at a pressure which is lower than the system pressure. Notes on detailed technical information about the pressure reducing valve: • The Hydraulic Trainer Volume 1/Bosch Rexroth AG Basic principles and components. The control set up on the training system (two actuators are controlled simultaneously at different pressures via a 4/3 directional valve) is to make the characteristics of a 3-way pressure reducing valve clear to the trainee. a pressure reducing valve is used. Chapter 12 • Technical data sheet RE 26564 Pressure reducing valve. The following Project 14 is intended to impart knowledge of the operating principle and the use of a pressure reducing valve. The pressure that can be set on a pressure reducing valve is always lower than the system pressure.07 Project 14: Pressure reducing valve Project/trainer information If a secondary actuator in a hydraulic control is to be controlled at a lower pressure independently of the system pressure. direct operated 14 . the pressure reducing valve influences the output pressure (actuator pressure). 14. In addition. 14 Fig. it is to be hydraulically pre-loaded. he needs information about the setting options and wants to know.Project 14: Pressure reducing valve  Bosch Rexroth AG I RE 00845/04.07 Project definition In Project 11 a workpiece is to be swiveled by a hydraulic motor in a machining station. In a further step of the project the same workpiece is to be clamped at reduced pressure. why a by-pass check valve is required. In order that the hydraulic motor only starts to rotate after clamping is completed. The customer wishes a solution with which the control can easily be realized and requires the associated technical documentation with the necessary system parameters.1 Practical example: Swiveling/clamping unit Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet of a pressure reducing valve (specialist qualification) • Handling of hydraulic components in line with functional needs . through discussions with the customer.Project 14: Pressure reducing valve  Bosch Rexroth AG I RE 00845/04. among others. dealing intensively with technical data sheet RE 26564. among others. • Deciding: Preparation of a schematic diagram sketch and selection of components. Preparation and documentation of the measured data. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? Notes 14 .07 Project steps • Informing: Accepting and understanding the order. • Executing: Set-up of the hydraulic control on the training system. • Planning: Planning and organizing of the customer order by. 14.4 Item 1.2 Item 2.2 Hydraulic circuit diagram: Machine tool control .2 Measuring glass 14 Power unit limit Fig.3 Item 1.1 Item 2.3 Item 0.07 Hydraulic circuit diagram Item 0.0 Rotate Clamp Item 0.Project 14: Pressure reducing valve  Bosch Rexroth AG I RE 00845/04.1 Item 1.1 Item 0.1 Item 1. Project 14: Pressure reducing valve  Bosch Rexroth AG I RE 00845/04.2 . 14.3 Wiring diagram for hydraulic circuit diagram Fig. 14.07 Electrical circuit diagram Stop 14 Control 4/3 directional valve Retraction Extension -Single-rod cylinderClockwise rotation -Hydraulic motor- Fig. Project 14: Pressure reducing valve  Bosch Rexroth AG I RE 00845/04. 14. cracking pressure 1 bar DS 2. rest position closed.1 3 Distributor plate with four ports DZ 4.N 1.1 3 Pressure gauge with hose and quick release coupling without check valve DZ 1. A.2 Type designation Symbol DD 2 14 .4 0.0 1 Fixed displacement motor with exteral leakage oil lines and two directions of rotation DM 2. T. flow possible in only one direction. B DW 13E 1.0.07 Component selection with parts list Item Qty 1.1 1. the cracking pressure can be adjusted by means of a spring DD 1.3 1 3-way pressure reducing valve 1 Check valve with spring.1 2 Direct operated pressure relief valve. spring centering of the central position and central position P.3 Component designation Table 14.0 1 Double-acting cylinder with single-sided piston rod ZY 1.1 1 4/3 directional valve with direct actuation by two solenoids.3 2.2/2.4 3 Hose with quick release coupling with check valve DZ 25 Hose VSK 1 1.1 Parts list for hydraulic circuit diagram Fig.1 . 1 and hydraulic circuit diagram Fig.2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. 14. 14.4 Recommended component arrangement with component designation for parts list Table 14.07 Connection block Measuring glass Component arrangement D Note: In the case of connection elements marked with “D”. the components can be connected directly with each other. Notes 14 . Fig.Project 14: Pressure reducing valve  Bosch Rexroth AG I RE 00845/04. Also the grid arrangement is Rexroth-specific and adapted for use on the training system. e.in this case also minimess lines . Warning Caution Make sure that all ports . that the system is switched off. Before starting work on the training system.3. i. The correct and proper fit of the component connections with hoses can be checked by slightly turning the hoses. including danger to life. Check on the system pressure gauge that the system is depressurized. It can cause injury when the system is opened.07 Safety notes To ensure the operability of plant and machinery. i. use hydraulic hoses DZ 25. 14 . check. whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open. Hydraulic systems can store pressure energy when at rest.pipes and hoses are connected or that the ports are blocked with plug screws or protective caps. Warning Caution If work on electrohydraulic components is carried out improperly. to which pressure gauges with minimess line DZ 1. check that the electrical ON/ OFF switch on the hydraulic power unit is pressed in. Connect the hydraulic control according to hydraulic circuit diagram Fig. Wire the electrical control according to wiring diagram Fig. 14.2 by means of hoses.Project 14: Pressure reducing valve  Bosch Rexroth AG I RE 00845/04. Leakage oil can drop through open ports on the floor and cause a risk of slipping. Execution of the order Set up the controls as described in the following: 1. Observe installation direction of check valve Item 1.4 are to be connected. and consequently to allow the recognition of potential risks. risks of injury and a safety risk can arise during operation of the system.4! Warning For the connections. Before commissioning the hydraulic control. safety regulations must be observed before and during the execution of the order.e. Mount the components required according to Table 14. before switching the hydraulic pump on. Hand-tighten the pressure gauge measuring lines at the relevant minimess connection of the hydraulic hose. Relevant sources of regulations are given in the introduction of the present manual.1 in a clearly arranged form on the training system according to the prepared circuit diagram. 14. M2.1 on the hydraulic motor (port B) to a load pressure of 40 bar (pressure gauge M2).2. Modify the hydraulic control. M3) in Table 14. 14 . Before making any conversion for further order processing. Switch the hydraulic pump on and inspect the set up control for leakage.Project 14: Pressure reducing valve Task 1  Bosch Rexroth AG I RE 00845/04. The hydraulic motor rotates against the load pressure of 40 bar. Enter the values measured during extending and retracting of the advance cylinder piston (pressure gauge M1. Set the system pressure on pressure relief valve Item 1. M3) in Table 14. Note: When the clamping piston retracts after operation of push-button S2 the cylinder moves against a clamping pressure of 20 bar provided via port A of the pressure reducing valve. and the clamping cylinder clamps at a pressure of 20 bar. Caution After having completed practical work on the training system switch the hydraulic pump off! No pressure gauge may indicate a pressure! Open the throttle check valve.1. Actuate push-button S4 to operate directional valve Item 1. Also enter the pressures in the extended and retracted condition.0.2. switch the hydraulic pump off! No pressure gauge may indicate a pressure! Caution Task 2 Control without by-pass check valve 5. Do not change the load pressure on hydraulic motor Item 2. 4.4 and the two connection hoses.0 rotates clockwise. Actuate push-button S4 to operate directional valve Item 1. Hydraulic motor Item 2. Set the clamping pressure to 20 bar on pressure reducing valve Item 1.0. M2.07 Control with by-pass check valve 2.3. Enter the values measured during extending and retracting of the clamping cylinder piston (pressure gauge M1. set pressure relief valve Item 2. 7. In this case.0 and the pressure on clamping cylinder Item 1.2 to 50 bar plus one turn. 6. Also enter the pressures in the extended and retracted condition. To this end remove by-pass check valve Item 1. No pressure gauge may indicate a pressure. the pressure reducing valve assumes a pressure relief function. 3. • When controlled via channel A. • When the pressure rises in port A of the pressure reducing valve (e.g.1 Without by-pass check valve DS 2. • When controlled from T to P the pressure relief valve on the hydraulic motor operates as check valve. pressure peaks/ changes in the load by the secondary actuator). 14 .1 M1 p in bar M2 p in bar M3 p in bar M1 p in bar M2 p in bar M3 p in bar Clamping cylinder extending → 20 15 3 20 15 3 Clamping cylinder extended → 45 40 20 45 40 20 Clamping cylinder retracting ← 45 15 20 48 0 26 Clamping cylinder retracted ← 50 0 0 50 0 0 Table 14. a pressure reducing valve operates as pressure relief valve.07 Measured values Measuring point → With by-pass check valve DS 2. Evaluating the work results with regard to the customer requirement • A pressure reducing valve can supply a secondary actuator with a lower pressure than the system pressure.Project 14: Pressure reducing valve 10 Bosch Rexroth AG I RE 00845/04.2 Values measured on the pressure reducing valve The values were measured at an oil temperature of approx. 20 °C. The values measured by the trainees can deviate by 10 %. the pressure increase is reduced to the tank via port T of the pressure reducing valve. • The system pressure must always be higher than the secondary pressure. The switching elements integrated in a piston-type pressure switch make or break an electrical circuit. • In the case of a piston-type pressure switch the pressure must exceed or fall below the set value in order that a switching process in initiated. When the set pressure is reached. In the following Project 15 knowledge can be imparted with regard to the operating principle and use of a piston-type pressure switch. Bourdon tube and piston type pressure switches are hydro-electrical switches. the return stroke is to be initiated. Chapter 15 • Technical data sheet RE 50060 Hydro-electrical pressure switch 15 .Project 15: Pressure switch  Bosch Rexroth AG I RE 00845/04. Electronic pressure switches are a combination of a pressure transducer. pressure switches are used. A cylinder is to be controlled by means of a 4/2 directional valve. and the pressure on the piston side controlled by a piston-type pressure switch. These are subdivided into: Bourdon tube. an indicator and a threshold switch. Pressure switches assume switching and monitoring functions in a hydraulic control. • The hydraulic pressure is used to switch an electrical signal via a micro-switch. The following knowledge is to be gained with this project task: • Piston-type pressure switches issue an electrical control signal. Notes on detailed technical information about the piston-type pressure switch: • The Hydraulic Trainer Volume 1/Bosch Rexroth AG Basic principles and components.07 Project 15: Pressure switch Project/trainer information If a control signal is to be switched in dependence upon a pressure. piston-type and electronic pressure switches. Based on the control set up on the training system the trainee is to understand the possible applications of a piston-type pressure switch. In the project order the trainee is to get familiar with the typical characteristics and the setting options of a piston-type pressure switch with the help of a practice-oriented experiment set-up on the training system. 07 Project definition Two hydraulic workpieces are to be pressed together in a fixture by means of a hydraulic cylinder. 15. The pressing velocity is to be adjustable. For his technical documentation. In the event of a fault of pressure monitoring. The customer wishes to obtain a proposed solution for an automatic. the customer requires a circuit diagram with parts list and functional description. the hydraulic cylinder is to retract automatically. it should be possible to release the pressing fixture electrically. The customer also wants to know the settable minimum pressing pressure.1 Practical example: International pressure indications on pressure switches for system monitoring Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet of a piston-type pressure switch (specialist qualification) • Handling of hydraulic components in line with functional needs 15 .Project 15: Pressure switch  Bosch Rexroth AG I RE 00845/04. hydraulic pressing process. After the pressing pressure was reached. Fig. • Executing: Set-up of the hydraulic control on the training system. among others. given system pressures. dealing intensively with technical data sheet RE 50060.Project 15: Pressure switch  Bosch Rexroth AG I RE 00845/04. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? Notes 15 . • Planning: Planning and organizing of the customer order by. through discussions with the customer.07 Project steps • Informing: Accepting and understanding the order. • Deciding: Preparation of a schematic diagram sketch and selection of components. Working out the setting options of the pressure switch at different. among others. 07 Hydraulic circuit diagram Item 1.4 Item 0.Project 15: Pressure switch  Bosch Rexroth AG I RE 00845/04.1 Item 0.2 Item 1.2 Hydraulic circuit diagram: Pressure switch Measuring glass 15 .0 Item 0.1 Item 1.3 Item 1. 15.3 Item 1.2 Power unit limit Fig. Project 15: Pressure switch  Bosch Rexroth AG I RE 00845/04. Fig.07 Electrical circuit diagram 15 Control 4/2 directional valve Extension -Single-rod cylinderNote: Retracting of the single-rod cylinder can additionally be controlled by means of push-button S1. 15.2 . 15.3 Wiring diagram for hdraulic circuit diagram Fig. electromechanical.3 1 Pressure switch.3 1.1 3 Pressure gauge with hose and quick release coupling without check valve DZ 1. 15.2 Type designation Symbol 15 . adjustable. free flow in one direction DZ 2.0 1 Double-acting cylinder with single-sided piston rod ZY 1. spring return DW 3E 1.2 1 Direct operated pressure relief valve.3 3 Component designation Table 15.1 .07 Component selection with parts list Item Qty 1.1 1 4/2 directional valve with solenoid actuation. the cracking pressure can be adjusted by means of a spring DD 1.4 1 Throttle check valve.0.Project 15: Pressure switch  Bosch Rexroth AG I RE 00845/04.1 1.1 Parts list for hydraulic circuit diagram Fig. adjustable DD 6E.2 1 Distributor plate with four ports DZ 4.1 1.4 hose with quick release coupling with check valve DZ 25 Hose VSK 1 0. 2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. 15. the components can be connected directly with each other. Also the grid arrangement is Rexroth-specific and adapted for use on the training system. ������ ������� Fig.4 Recommended component arrangement with component designation for parts list Table 15.Project 15: Pressure switch  Bosch Rexroth AG I RE 00845/04. Notes 15 .07 Component arrangement ������ ����� ������� ������ ������ ������ � ������ ����� ����� ������ D � � � ������� ����� � Connection block � Measuring glass ������ ����� � Note: In the case of connection elements marked with “D”.1 and hydraulic circuit diagram Fig. 15. risks of injury and a safety risk can arise during operation of the system. and consequently to allow the recognition of potential risks. Observe direction of installation of the throttle check valve! Danger For connections. No pressure gauge may indicate a pressure. Set piston-type pressure switch Item 1. safety regulations must be observed before and during the execution of the order.2. Set the system pressure to 30 bar on pressure relief valve Item 1.3 to maximum by turning the setscrew completely in using an Alllan key 10 A/F. Relevant sources of regulations are given in the introduction of the present manual. It can cause injury when the system is opened.in this case also minimess lines . Before commissioning the hydraulic control. before switching the hydraulic pump on.e. Before starting work on the training stand. Warning Caution Make sure that all ports . Use the system pressure gauges to check that the system is depressurized. whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open.3. that the system is switched off.2 by means of hoses. including danger to life. Switch the hydraulic pump on and inspect the set up control for leakage. Wire the electrical control according to wiring diagram Fig.pipes and hoses are connected or that the ports are blocked with plug screws or protective caps. use hydraulic hoses DZ 25. Connect the hydraulic control according to hydraulic circuit diagram Fig. Execution of the order Set up the control as described below: 1. i.07 Safety notes To ensure the operability of plant and machinery.e. Mount the components required according to the parts list in a clearly arranged form on the training system according to the prepared circuit diagram. The correct and proper fit of the component connections with hoses can be checked by slightly turning the hoses. to which pressure gauges with minimess line DZ 1. check. 2. Hand-tighten the pressure gauge measuring lines at the relevant minimess connection of the hydraulic hose. 15 .Project 15: Pressure switch  Bosch Rexroth AG I RE 00845/04. Hydraulic systems can store pressure energy when at rest. 15. Leakage oil can drop through open ports on the floor and cause a risk of slipping. check that the electrical ON/ OFF switch on the hydraulic power unit is pressed in. 15. i. Warning Caution If work on electrohydraulic components is carried out improperly.4 are to be connected. Adjust the pressing pressure on piston-type pressure switch Item 1. To this end. • In the case of a piston-type pressure switch.2. Set the pressures given in Table 15.05 m/s by means of throttle check valve Item 1. • The hydraulic pressure is used to switch an electrical signal by means of a micro-switch. 4. calculate the velocity as a function of the measured extension time and the stroke length. 5. Check that the pressing cylinder extends and retracts correctly while the throttle check valve is open. 15 . Caution After having completed practical work on the training system switch the hydraulic pump off! No pressure gauge may indicate a pressure! Open the throttle check valve. Actuate push-button S2 to operate directional valve Item 1.2 Pressure monitoring of the hydraulic cylinder The values were measured at an oil temperature of approx.2 and verify whether the cylinder retracts automatically.4.Project 15: Pressure switch  Bosch Rexroth AG I RE 00845/04. Evaluating the work results with regard to the customer requirement • Piston-type pressure switches output an electrical signal.1. Enter the results in Table 15. 20 °C. the pressure must exceed or fall below the set value in order to initiate a switching process. Adjust the extension velocity of the pressing piston to a forward speed of 0. Measured values Pressure relief valve p in bar Retracts automatically Yes/no 20 No 28 No 30 Yes 32 Yes 40 Yes Table 15. The values measured by the trainees can deviate by 10 %.07 3. extend the pressing piston to the end position.3 (release spring) so that the pressing cylinder piston retracts automatically. To this end. Project 15: Pressure switch 10 Bosch Rexroth AG I RE 00845/04.07 Notes 15 . On electronic pressure switches. Notes on detailed technical information about the piston-type pressure switch: • The Hydraulic Trainer Volume 1/Bosch Rexroth AG Basic principles and components. the trainee is to get to know the hysteresis of a piston-type pressure switch. which can be attributed to the individual design. then the reset point at the desired distance. and a pressure relief valve installed in a by-pass. • Hysteresis can have different amounts. In the project order the trainee is to get familiar with the hysteresis of a piston-type pressure switch through a practical experiment set-up on the training system. With the help of a 24 V bulb. The switching elements installed in a pressure switch close or open an electric circuit. On the basis of the control set up on the training system. While the system pressure rises.07 Project 16: Pressure switch/hysteresis Project/trainer information If pressures are to be processed as signals in a hydraulic control. A pressure switch is a converter.Project 16: Pressure switch hysteresis  Bosch Rexroth AG I RE 00845/04. hysteresis can be adjustable. which converts an incoming hydraulic pressure into an electrical signal. when the system pressure fluctuates around the command value. the trainee is to gain the following knowledge: • A piston-type pressure switch always has a hysteresis. when the system pressure falls again. the output switches when the switching point (SP) is reached. The difference in the values is called hysteresis (Greek hysteros: later). Through this project task. he/she can set given values and measure the hysteresis by way of the hydraulic pressure. which serves as control unit. • Hysteresis is the difference of switching points at rising and falling pressure. P SP rP 1 0 1 0 Hysteresis Hno (normally open) Hnc (normally closed) Diagram 16. Chapter 15 • Technical data sheet RE 50060 Hydro-electrical pressure switch 16 . In the following Project 16 knowledge can be imparted of the practical effects of hysteresis on a piston-type pressure switch.1 Hysteresis Adjustable hysteresis on electronic pressure switches Hysteresis maintains the switched state of the output stable. The switching point at increasing pressure and at falling pressure varies due to friction. • On certain pressure switches. the output only switches when the reset point (rP) is reached. pressure switches must be used. the hysteresis is adjustable: Firstly the switching point is determined. Project 16: Pressure switch hysteresis  Bosch Rexroth AG I RE 00845/04. whether this is always the same. Lower switching pressure in bar → Fig. he wants to know. and if so.07 Project definition Scatter min.1 Practical example: Piston-type pressure switch 16 Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet of a piston-type pressure switch (specialist qualification) • Handling of hydraulic components in line with functional needs . In addition. Switching pressure differential in bar → Pressure stage 100 bar max. whether he can utilize this for the sequence of his control. For his technical documentation the customer requires detailed information about the hysteresis of this piston-type pressure switch. 16. As described in Project 15 a customer uses a piston-type pressure switch in hydraulic pressing equipment. technical data sheet RE 50060.Project 16: Pressure switch hysteresis  Bosch Rexroth AG I RE 00845/04. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? Notes 16 . • Executing: Set-up of the hydraulic control on the training system. • Planning: Planning and organizing the customer order using. among others.07 Project steps • Informing: Accepting and understanding the order. Working out the hysteresis of a piston-type pressure switch at various. among others. through discussions with the customer. • Deciding: Preparation of a schematic diagram sketch and selection of components. given system pressures. 1 Item 1.2 Item 0.07 Hydraulic circuit diagram Item 1.1 Item 1.0 Measuring glass Power unit limit 16 Fig.Project 16: Pressure switch hysteresis  Bosch Rexroth AG I RE 00845/04.2 Hydraulic circuit diagram: Pressure switch hysteresis . 16. Fig.07 Electrical circuit diagram 16 Note: The pressure switch is supplied with voltage via push-button S1.2 .3 Wiring diagram for hydraulic circuit diagram Fig.Project 16: Pressure switch hysteresis  Bosch Rexroth AG I RE 00845/04. 16. 16. 1 Table 16.1 1. adjustable 0.1 1 Pressure gauge with hose and quick release coupling without check valve DZ 1.1 Parts list for hydraulic circuit diagram Fig. electromechanical.1 1 Pressure switch.2 1.4 2 Hose with quick release coupling with check valve DZ 25 Hose VSK 1 Symbol DD 6E. 16. the cracking pressure can be adjusted by means of a spring DD 1.2 16 . adjustable DF 1.2 1 Throttle valve.0 1 Direct operated pressure relief valve.07 Component selection with parts list Item Qty Component designation Type designation 1.Project 16: Pressure switch hysteresis  Bosch Rexroth AG I RE 00845/04. 4 Recommended component arrangement with component designation for parts list Table 16. the components can be connected directly with each other. 16.1 and hydraulic circuit diagram Fig. Also the grid arrangement is Rexroth-specific and adapted for use on the training system. Notes 16 . Fig.07 Connection block Measuring glass Component arrangement D Note: In the case of connection elements marked with “D”.2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations.Project 16: Pressure switch hysteresis  Bosch Rexroth AG I RE 00845/04. 16. 2 by means of hoses. 16. check. 4.e. Connect the hydraulic control according to hydraulic circuit diagram Fig.1 to 30 bar. Before starting work on the training stand.4 are to be connected.Project 16: Pressure switch hysteresis  Bosch Rexroth AG I RE 00845/04. i. It can cause injury when the system is opened. close throttle Item 1. No pressure gauge may indicate a pressure. Hydraulic systems can store pressure energy when at rest. risks of injury and a safety risk can arise during operation of the system. Warning Caution If work on electrohydraulic components is carried out improperly. whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open.07 Safety notes To ensure the operability of plant and machinery. Use the system pressure gauges to check that the system is depressurized. For connections.0. use hydraulic hoses DZ 25. 16. Execution of the order Set up the controls as described in the following: 1. to which pressure gauges with minimess line DZ 1. Set piston-type pressure switch Item 1.1 in a clearly arranged form on the training system according to the prepared circuit diagram. Switch the hydraulic pump on and inspect the set up control for leakage. including danger to life. To this end. Mount the components required according to Table 16. 3.3. to this end. before switching the hydraulic pump on.in this case also minimess lines . Hand-tighten the pressure gauge measuring lines at the relevant minimess connection of the hydraulic hose. i. safety regulations must be observed before and during the execution of the order. and consequently to allow the recognition of potential risks. set pressure relief valve Item 1.e. check that the electrical ON/ OFF switch on the hydraulic power unit is pressed in. Relevant sources of regulations are given in the introduction of the present manual. that the system is switched off. 16 . Set the system pressure to 25 bar on pressure relief valve Item 1.2 and operate push-button S1.pipes and hoses are connected or that the ports are blocked with plug screws or protective caps. 2. Warning Caution Make sure that all ports . Wire the electrical control according to wiring diagram Fig. Before commissioning the hydraulic control. Leakage oil can drop through open ports on the floor and cause a risk of slipping.0 to 30 bar. The correct and proper fit of the component connections with hoses can be checked by slightly turning the hoses. • On a piston-type pressure switch. 16 .Project 16: Pressure switch hysteresis  Bosch Rexroth AG I RE 00845/04. The pressure indicated by the pressure gauge should be 27.5 bar. During this. Slowly reduce the system pressure until lamp H1 goes out. lamp H1 goes on. When the pressure rises to 30 bar.2 bar. Evaluating the work results with regard to the customer requirement • A piston-type pressure switch always features hysteresis. This switching difference is called hysteresis.07 Slowly increase the system pressure to 30 bar while observing indicator lamp H1 on the electrical control. lamp H1 must not go out. • The pressure switch responds at increasing and falling pressure. Increase the system pressure by further 5 bar to 35 bar. Note: The value given under point 5 can deviate by 1 . 5. Caution After having completed practical work on the training system switch the hydraulic pump off! No pressure gauge may indicate a pressure! Open the throttle check valve. hysteresis is not adjustable. 07 Notes 16 .Project 16: Pressure switch hysteresis 10 Bosch Rexroth AG I RE 00845/04. Accumulators may only be protected by pressure relief valves. • The amount of oil available for withdrawal depends on the accumulator size. which comply with Directive 97/23/EC. the nitrogen pre-charge pressure and the system pressure. for damping. a cylinder should be operable also in the event of a failure. for holding pressures constant and for vehicle suspension. Through this project task. You could also explain how to check the gas pre-charge pressure. The rating. The following Project 17 is intended to impart knowledge of the possible applications of a diaphragm-type accumulator as energy storage. soldering or carrying out mechanical work on pressure equipment is prohibited.Project 17: Hydraulic accumulator  Bosch Rexroth AG I RE 00845/04. Depending on their design. the following knowledge is to be acquired: • Due to the compressibility of the filled-in gas. Pressure equipment must not be charged with oxygen or air. A hydraulic accumulator is a pressure vessel with a separating element. hydraulic accumulators are classified as: Piston-type. equipment and operation are regulated by "Technischen Regeln Druckbehälter“ (TRB) (technical rules for pressure vessels). the nitrogen pre-charge pressure and the pressure difference between the minimum and maximum working pressure. The installation. On the basis of the control set up on the training system the trainee is to work out the possible application of a hydraulic accumulator as energy storage. 17 . bladder-type and diaphragm-type accumulators. for example of the hydraulic pump. The usable oil volume can be calculated on the basis of a hydraulic cylinder that is controlled by a 4/3 directional valve at different system pressures. Warning Caution Welding. in a hydraulic control.07 Project 17: Hydraulic accumulator Project/trainer information If. a diaphragm-type accumulator can be used for storing energy. the hydraulic accumulator is completely discharged. Hydraulic accumulators are used for storing energy. • If the system pressure falls below the nitrogen pre-charge pressure. in which energy is stored. Safety notes (Excerpt from currently valid safety regulations . • The oil volume that can be stored in the hydraulic accumulator depends on the size of the accumulator. Pressure equipment (accumulators) must not be opened before the gas and fluid sides were depressurized. In the project order the trainee is to understand the behavior of a hydraulic cylinder in the event of a hydraulic pump failure and the withdrawal of energy from a diaphragm-type accumulator in a practical experiment set-up on the training system. manufacture and testing must comply with AD sheets. Accumulators contain nitrogen (risk of suffocation). for leakage oil compensation. Hydraulic accumulators are pressure vessels and are subject to national regulations valid at the place of installation. Pressure accumulators may only be installed.not exhaustive). repaired and put into service by specialist personnel trained in the field of hydraulics. In Germany. the energy required for this can be taken from a hydraulic accumulator. these are the health and safety at work regulations (BetrSichV). He uses various system pressures and therefore requires documents that describe the usable volume. a tool is to be moved by means of a hydraulic cylinder into and out of the machining area. i. whether the usable accumulator volume is sufficient. he is interested in test documents such as a table that shows the various system pressures and the usable oil volume. he would like to know whether he selected the correct accumulator size.1 Practical example: Bladder and diaphragm-type accumulators with accumulator safety block . the tool most be extended by means of stored energy. In addition.e. In the event of a hydraulic pump failure. 17 Fig.07 Notes on detailed technical information about the hydraulic accumulator: • The Hydraulic Trainer Volume 1/Bosch Rexroth AG Basic principles and components. Since the customer has never utilized an accumulator before.Project 17: Hydraulic accumulator  Bosch Rexroth AG I RE 00845/04. Chapter 9 • Technical data sheet RE 50130 Accumulator safety valve • Technical data sheet RE 50150 Diaphragm-type accumulator Project definition In a fixture. 17. given system pressures. • Executing: Set-up of the hydraulic control on the training system and calculation of the usable oil volume at different. • Planning: Planning and organizing the customer order by.07 Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet of a hydraulic accumulator (specialist qualification) • Handling of hydraulic components in line with functional needs Project steps • Informing: Accepting and understanding the order.Project 17: Hydraulic accumulator  Bosch Rexroth AG I RE 00845/04.Basic Principles) and the technical data sheet RE 50130/Accumulator safety block. through discussions with the customer. • Deciding: Preparation of a schematic diagram sketch and selection of components. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? 17 . and of the precharge pressure. working out the topic of hydraulic accumulators (The Hydraulic Trainer . among others. among others. 17.2 Item 1.1 Item 0.07 Hydraulic circuit diagram Item 0.1 Item 1.2 Measuring glass Power unit limit 17 Fig.Project 17: Hydraulic accumulator  Bosch Rexroth AG I RE 00845/04.0 Item 1.4 Lead- sealed Item 1.2 Hydraulic circuit diagram: Hydraulic accumulator .3 Item 1. 07 Electrical circuit diagram Circulation Control 4/3 directional valve Fig.2 Retraction Extension -Single-rod cylinder- 17 .Project 17: Hydraulic accumulator  Bosch Rexroth AG I RE 00845/04. 17.3 Wiring diagram for hydraulic circuit diagram Fig. 17. 1 1.0 1 Double-acting cylinder with single-sided piston rod 1. T.2 Component designation Table 17.1 2 Pressure gauge with hose and quick release coupling without check valve DZ 1.2 3 Distributor plate with four ports DZ 4.3 1 Check valve with spring. rest position closed. B DW 13E 1. flow possible in only one direction.1 1. 17.Project 17: Hydraulic accumulator  Bosch Rexroth AG I RE 00845/04. A.07 Component selection with parts list Item Qty 1.1 . cracking pressure 1 bar DS 2.4 1 Accumulator safety block for diaphragm-type accumulator DZ 3.2 1 Direct operated pressure relief valve.1 1 4/3 directional valve with direct actuation by two solenoids.4 1 hose with quick release coupling with check valve DZ 25 Hose VSK 1 0.0.3 17 .2 Type designation Symbol ZY 1.1 Parts list for hydraulic circuit diagram Fig. the cracking pressure can be adjusted by means of a spring DD 1. spring centering of the central position and central position P. 1 and hydraulic circuit diagram Fig.Project 17: Hydraulic accumulator  Bosch Rexroth AG I RE 00845/04. 17. the components can be connected directly with each other.2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. Notes 17 . Fig.07 Connection block Measuring glass Component arrangement D Note: In the case of connection elements marked with “D”. Also the grid arrangement is Rexroth-specific and adapted for use on the training system.4 Recommended component arrangement with component designation for parts list Table 17. 17. 07 Safety notes To ensure the operability of plant and machinery.3. Connect the hydraulic control according to hydraulic circuit diagram Fig. check that the electrical ON/ OFF switch on the hydraulic power unit is pressed in. No pressure gauge may indicate a pressure. Hand-tighten the pressure gauge measuring lines at the relevant minimess connection of the hydraulic hose. Switch the hydraulic pump on and inspect the set up control for leakage. Hydraulic systems can store pressure energy when at rest. It can cause injury when the system is opened. Wire the electrical control according to wiring diagram Fig.2 by means of hoses. i. 2. i. Execution of the order Set up the control as described below: 1. and consequently to allow the recognition of potential risks.4 are to be connected.pipes and hoses are connected or that the ports are blocked with plug screws or protective caps. Check on the system pressure gauge that the system is depressurized. The correct and proper fit of the component connections with hoses can be checked by slightly turning the hoses. 17. that the system is switched off. safety regulations must be observed before and during the execution of the order. Hand lever (P) on the accumulator safety valve open.in this case also minimess lines . 17. before switching the hydraulic pump on. Mount the components required according to the parts list in a clearly arranged form on the training system according to the prepared circuit diagram.e.Project 17: Hydraulic accumulator  Bosch Rexroth AG I RE 00845/04. Warning Caution If work on electrohydraulic components is carried out improperly. including danger to life. Before commissioning the hydraulic control.3. check. 17 .e. Warning For connections. to which pressure gauges with minimess line DZ 1. Before starting work on the training system. Leakage oil can drop through open ports on the floor and cause a risk of slipping. Warning Caution Observe direction of installation of check valve Item 1. rotary knob (T) of the discharge valve closed. Make sure that all ports . Relevant sources of regulations are given in the introduction of the present manual. risks of injury and a safety risk can arise during operation of the system. use hydraulic hoses DZ 25. whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open. 2. 6. Close the shut-off valve (hand lever P) of accumulator safety valve Item 1. Repeat the experiment with the accumulator charging pressures given in Table 17. Carefully open the discharge valve (rotary knob T) on the accumulator safety valve until the pressure shown on M2 slowly falls. The system pressure is now isolated in the accumulator. Task 2 Switch the hydraulic pump off.2.Project 17: Hydraulic accumulator Task 1  Bosch Rexroth AG I RE 00845/04. including the residual stroke during extending and retracting. The pressure slowly decompresses down to the gas charging pressure and then rapidly falls to 0 bar.d St2 • ( π • e • s • z 4 V = useful volume of the hydraulic accumulator dK = bore of the hydraulic cylinder (25 mm) dSt = piston rod diameter of the hydraulic cylinder (16 mm) S = stroke length of the hydraulic cylinder (200 mm) a = number of complete extending strokes e = number of complete retracting strokes x = residual stroke of the extending hydraulic cylinder z = residual stroke of the retracting hydraulic cylinder ) dm3    17 . Switch the hydraulic pump off.0 by operating push-buttons S4 and S2 until the piston does no longer move. Usable accumulator oil volume: 4. Extend and retract cylinder Item 1.2.2. Set the system pressure to 40 bar on pressure relief valve Item 1.2 to 10 bar.0 by operating push-buttons S4 and S2 and provide markings on the base plate at the end positions (the stroke should be 200 mm). and enter the values in Table 17. close the discharge valve by means of the rotary knob (T).2 to 15 bar. Retract cylinder Item 1. Repeat the experiment set-up as described under point 5 and enter the measurement results in Table 17. The pressure value at which the pressure starts to fall quickly is the nitrogen charging pressure. Extend and retract cylinder Item 1. 5.0 to the basic position. Evaluating Calculation of the useful volume of the accumulator On the basis of the total number of strokes of the hydraulic cylinder the useful volume of the hydraulic accumulator can be calculated according to the following formula. Open the hand lever (P) on the accumulator safety block. The required oil volume is now taken from the hydraulic accumulator.07 Check the nitrogen pre-charge pressure: 3. Note the number of strokes (extending and retracting). Caution After having completed practical work on the training system switch the hydraulic pump off! No pressure gauge may indicate a pressure! Unload the hydraulic accumulator via the accumulator safety valve (rotary knob T). Set the system pressure on pressure relief valve Item 1. Switch the hydraulic pump on and set the system pressure on pressure relief valve Item 1. The system pressure can also be read off from pressure gauge M2. Switch the hydraulic pump on again.4. V = d K2 • π 4 ( a • s + x ) + (d 2 K ) . 07 Cylinder comes to a halt while extending Cylinder comes to a halt while retracting z=s-y Fig.1) Measured values Hydraulic accumulator pre-charge pressue p0 = 10 bar Hydraulic No.Project 17: Hydraulic accumulator 10 Bosch Rexroth AG I RE 00845/04.36 25 3 3 0 50 0. 17.57 Table 17.2 Useful volume of hydraulic accumulator The values were measured at an oil temperature of approx.52 40 3 3 160 0 0.47 35 3 3 100 0 0. prepare a characteristic curve (Diagram 17.25 20 2 2 95 0 0. The values measured by the trainees can deviate by 10 %. of complete strokes accumulator Extending a Retracting e charging pressure M2 p in bar Residual stroke in mm Retracting x Extending z Useful volume V in dm3 10 0 0 0 0 0 15 1 1 195 0 0.6 Residual stroke of the hydraulic cylinder After having calculated the useful volume.55 45 4 3 0 0 0. 17 . 20 °C.42 30 3 3 10 0 0. the nitrogen pre-charge pressure and the system pressure.1 0 0 10 20 30 Charging pressure M2 p in bar 40 50 Diagram 17. diaphragm-type accumulators can be used as energy storage.6 Useful volume V in l 0.4 0.07 0.2 0. • The oil volume stored in the hydraulic accumulator depends on the accumulator size.3 0. • The effective useful volume of the hydraulic accumulator depends on the accumulator size.1 re Table 17. the nitrogen pre-charge pressure and the pressure difference between minimum and maximum working pressure.Project 17: Hydraulic accumulator 11 Bosch Rexroth AG I RE 00845/04. the hydraulic accumulator is completely unloaded.5 0. • The hydraulic accumulator is charged when the system pressure is higher than the nitrogen pre-charge pressure. • If the system pressure falls below the nitrogen pre-charge pressure.2 Evaluating the work results with regard to the customer requirement • Due to the compressibility of the filled in gas. 17 . 07 Notes 17 .Project 17: Hydraulic accumulator 12 Bosch Rexroth AG I RE 00845/04. • In the case of a regenerative circuit. • With a regenerative circuit. because the force of the piston rod side counteracts the piston side. The hydraulic cylinder is controlled by a 4/2 directional valve.07 Project 18: Regenerative circuit Project/trainer information If in a hydraulic control the extension velocity of a hydraulic cylinder (area ratio 2 : 1) is to be doubled. With the help of the control set up on the training system the trainee is to get familiar with the typical behavior of a regenerative circuit. The working pressure is permanently applied to both areas (piston and annulus piston area) of the hydraulic cylinder when the piston is extending. the oil volume of the piston rod side is directly fed to the piston side. In a regenerative circuit. In the project order the trainee is to work out the behavior of a hydraulic cylinder. Notes on detailed technical information about the regenerative circuit: • Technical data sheet RE 48005/RE 48015 Velocity controls for on/off directional valves 18 . a regenerative circuit (recovery of the returning oil) can be employed. when the oil volume of the piston rod side is directly fed to the piston side during extending. In the following Project 18 knowledge can be imparted of how to increase the velocity without enlarging the pump displacement. the extending piston is pre-loaded. During extending. the trainee is to gain the following knowledge: • For a single-rod cylinder the area ratio can be calculated on the basis of the piston area and the annulus piston area. the required pump displacement can be reduced. the volume of the piston rod side is directly fed to the piston side.Project 18: Regenerative circuit  Bosch Rexroth AG I RE 00845/04. On the basis of a practical experiment set-up on the training system. The piston velocity is to be adjustable by means of a flow control valve. A disadvantages is the force loss during extending. The advantages of this control are the smaller pump displacement and the approximately identical extension and retraction velocity of the hydraulic cylinder. the customer wants to know which effect the increase in the cycle time has on the advance force. The advance velocity (extending time of the hydraulic cylinder) is to be adjustable independently of the load.Project 18: Regenerative circuit  Bosch Rexroth AG I RE 00845/04. he requires the associated documentation such as the hydraulic circuit diagram with parts list. Fig. He also requires a table of the travel times of the hydraulic cylinder with different flow control settings.07 Project definition On a machine tool the velocity of a feed cylinder is to be increased and thus the cycle time of the system shortened without changing the pump flow. 18. pressure and flow control valve 18 Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet for velocity controls (specialist qualification) • Handling of hydraulic components in line with functional needs .1 Practical example: Control block with hydraulic components such as directional. Moreover. In order that the customer can understand the circuit structure of the control. • Deciding: Preparation of a schematic diagram sketch and selection of components. • Executing: Set-up of the hydraulic control on the training system. working out the technical data sheets relating to velocity controls. • Planning: Planning and organizing the customer order by. through discussions with the customer. among others.07 Project steps • Informing: Accepting and understanding the order. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? Notes 18 .Project 18: Regenerative circuit  Bosch Rexroth AG I RE 00845/04. Preparation of a table of travel times and velocities and a comparison of pros and cons. among others. 0 Item 0.2 Item 0.3 Measuring glass Power unit limit 18 Fig.Project 18: Regenerative circuit  Bosch Rexroth AG I RE 00845/04. 18.1 Item 1.2 Hydraulic circuit diagram: Regenerative circuit .3 Item 1.2 Item 0.07 Hydraulic circuit diagram Item 1.1 Item 1. Project 18: Regenerative circuit  Bosch Rexroth AG I RE 00845/04.3 Wiring diagram for hydraulic circuit diagram Fig. 18.2 . 18.07 Electrical circuit diagram Control 4/2 directional valve Extension -Single-rod cylinder- 18 Fig. 1 1 Distributor plate with four ports DZ 4.1 3 Pressure gauge with hose and quick release coupling without check valve DZ 1.0.2 1 2-way flow control valve.07 Component selection with parts list Item Qty 1.1 Parts list for hydraulic circuit diagram Fig.3 1 Direct operated pressure relief valve.Project 18: Regenerative circuit  Bosch Rexroth AG I RE 00845/04. the cracking pressure can be adjusted by means of a spring DD 1.2 18 . for one direction of flow.1 1 Direct operated pressure relief valve. the cracking pressure can be adjusted by means of a spring 1. adjustable. with by-pass check valve 1. largely independent of viscosity and pressure differential.0 1 Double-acting cylinder with single-sided piston rod 1.1 .4 3 Hose with quick release coupling with check valve DZ 25 Hose VSK 1 0. adjustable.3 Component designation Type designation Symbol ZY 1 DW 3E DF 3 Table 18. 18. Also the grid arrangement is Rexroth-specific and adapted for use on the training system.07 Connection block Measuring glass Component arrangement D Note: In the case of connection elements marked with “D”.4 Recommended component arrangement with component designation for parts list Table 18. Notes 18 . 18. Fig.1 and hydraulic circuit diagram Fig.Project 18: Regenerative circuit  Bosch Rexroth AG I RE 00845/04. the components can be connected directly with each other. 18.2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. risks of injury and a safety risk can arise during operation of the system.2. Warning Caution Make sure that pipes or hoses are connected to all connections . check that the electrical ON/ OFF switch on the hydraulic power unit is pressed in.07 Safety notes To ensure the operability of plant and machinery. enter the extension time and pressures M3 and M2 at the end position of hydraulic cylinder Item 1. to which pressure gauges with minimess line DZ 1. For connections. Check on the system pressure gauge that the system is depressurized.3 to 50 bar plus one turn. use hydraulic hoses DZ 25. i.0. Set flow control valve Item 1. Connect the hydraulic control according to hydraulic circuit diagram Fig.Project 18: Regenerative circuit  Bosch Rexroth AG I RE 00845/04. safety regulations must be observed before and during the execution of the order. Extend hydraulic cylinder Item 1. or that the connections are plugged by means of plug screws or protective caps. Warning Caution If work on electrohydraulic components is carried out improperly. Mount the components required according to parts list Table 18. It can cause injury when the system is opened. Switch the hydraulic pump on and inspect the set up control for leakage. i.0 by operating push-button S1. Before starting work on the training system. Before commissioning the hydraulic control. 2.e. before switching the hydraulic pump on.0 in Table 18. 18 . Relevant sources of regulations are given in the introduction of the present manual. Hydraulic systems can store pressure energy when at rest. Measure the extension time.3.1 in a clearly arranged form on the training system according to the prepared circuit diagram. whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open. The correct and proper fit of the component connections with hoses can be checked by slightly turning the hoses.2 by means of hoses. Hand-tighten the pressure gauge measuring lines at the relevant minimess connection of the hydraulic hose. 18. Execution of the order Set up the control as described below: 1. Leakage oil may drip through open connections and cause a slipping risk. No pressure gauge may indicate a pressure. including danger to life.e. Wire the electrical control according to wiring diagram 18. check. Set the system pressure on pressure relief valve Item 1. and consequently to allow the recognition of potential risks.1. that the system is switched off.2 to scale position 1.in this case also to minimess lines. 3.4 are to be connected. 0 in Table 18.4. which causes the piston of hydraulic cylinder Item 1. Calculation of the area ratio of single rod cylinder ZY1 used in the regenerative circuit.8 and 2.9 cm2 = 1.07 Operate push-button S1. Set flow control valve Item 1.2 Measured values of regenerative circuit The values were measured at an oil temperature of approx.3 6.0 to retract again. switch the hydraulic pump off! No pressure gauge may indicate a pressure! Open the throttle check valve.7 17.0 and enter the individual measuring results in Table 18.4 23. Required dimensions of the hydraulic cylinder: Piston diameter D Piston rod diameter d Solution: D2 • π = 4.6 14.9 cm2 4 D2 .5 7.6 10.6 cm 18 . 6.5 37.1 1.Project 18: Regenerative circuit  Bosch Rexroth AG I RE 00845/04.5 23.6 Extended Retracted 50 0 50 50 8.4 29.0 1.0 Extended Retracted 50 0 50 50 5.7 1.2.2 as described under point 3. 20 °C.2 13.0 Extended Retracted 50 0 50 50 19 28 10.69 : 1 = 2.1 9.2 Extended Retracted 50 0 50 50 16.9 cm2 4 4.2. 1.6. 1.8 2.3 19.5 20.7 12.4 Extended Retracted 50 0 50 50 11.689 A1 = ( ) Area ratio A1 : A2 = 1.d 2 • π A2 = = 2. 9 cm2 : 2. enter the retraction time of the piston and pressures M3 and M2 at the end position of hydraulic cylinder Item 1.8 Extended Retracted 50 0 50 50 6.8 Table 18. 1. Scale position Cylinder piston Flow control valve M2 p in bar M3 p in bar Travel time t in s Velocity v in mm/s 1.1. Enter the calculated traversing velocities of the feed cylinder as characteristic curve in Diagram 18.7 30. Caution After having completed practical work on the training system.2 successively to scale positions 1. The values measured by the trainees can deviate by 10 %.5 cm = 1.8 8.6 1. 4. 5. e. The cylinder force during extending consequently becomes Fext = p  AK – p  AR 18 Fext = p  ASt = p  (AK – AR ) and the piston velocity with pump displacement qP Vext = qP AK – AR = qP AK AR ASt ASt because the pump flow must only fill the space that corresponds to the piston rod area.1 re Table 18. For information. i. Note: When neglecting the pressure drop in the lines and the directional valve. Single-rod cylinder A special type of circuit for a single-rod cylinder is the regenerative circuit.5 0 0 0.2 As mentioned in the introduction. the remaining useful force is the force of piston rod area FST.07 Cylinder in Cylinder out 4 3.5 1 0. . the cylinder is extended when the directional valve takes the spool position … and the oil displaced from the piston rod chamber is fed together with the pump displacement to the piston chamber. In this circuit. including the required calculation formula.Project 18: Regenerative circuit 10 Bosch Rexroth AG I RE 00845/04. please find below notes on pressures and flows for a single-rod cylinder controlled in a regenerative circuit.5 2 1.5 Diagram 18. the pressure is identical on both sides of the cylinder.5 Position of flow control valve DF3 2 2.5 Velocity v in cm/s 3 2. a disadvantage of the regenerative circuit is that piston force FK counteracts annulus piston force FR.5 1 1. 07 For retracting of the cylinder with spool position … of the directional valve. the force is calculated as follows: Fretr = pB  AR – pA  AK the retraction velocity q Vretr = P AR Thus. it becomes obvious that with an area ratio of ϕ= AK =2 AR the extension and retraction velocities become identical. Vext = qP AK – AR = qP 2  AR – AR qP = AR = Vretr The following is valid: Vext Vretr where ϕ= = AK AR consequently Vext Vretr Vext Vretr = = qP  AR (AK – AR )  qP = AR AK – AR → AK = ϕ  AR AR ϕ  AR – AR = AR AR  (ϕ – 1) = 1 ϕ –1 1 ϕ –1 18 .Project 18: Regenerative circuit 11 Bosch Rexroth AG I RE 00845/04. 18 . • In a regenerative circuit.Project 18: Regenerative circuit 12 Bosch Rexroth AG I RE 00845/04. the volume displaced on the piston rod side while the piston is extending is fed to the piston side. • In a regenerative circuit. the required pump displacement can be reduced.07 AK AR ASt F1 (out) F2 (back) ∆pmin pA qB qA qtotal = qB + qP qA qP Evaluating the work results with regard to the customer requirement • The area ratio of a single-rod cylinder can be calculated on the basis of the piston area and the annulus piston area. Notes on detailed technical information on the rapid speed advance circuit: • Technical data sheet RE 48005 Velocity controls for on/off directional valves 19 . On the basis of a practice-oriented experiment set-up on the training system the trainee is to gain the following knowledge: • With a rapid speed advance control the hydraulic cylinder extends at maximum velocity without any throttling. In the project order the trainee is to work out the behavior of a hydraulic cylinder when a flow control valve is activated by means of a directional valve while the cylinder is extending. With this velocity control. a flow control valve is cut in and out on the piston rod side of the extending hydraulic cylinder.07 Project 19: Rapid speed/creep speed control Project/trainer information A rapid speed/creep speed control can be used in a hydraulic circuit to control the advance velocity of a hydraulic cylinder independently of the load. • The return stroke of the hydraulic cylinder is performed at maximum velocity. Here. On basis of the control set up on the training system the trainee is to understand the typical behavior of a single-rod cylinder in such a rapid speed advance control. With an additional 4/2 directional valve the oil volume of the piston rod side is fed via a flow control valve to the tank. The return stroke is performed at the maximum velocity possible. • Pressure intensification occurs when a flow control valve is activated on the piston rod side.Project 19: Rapid speed / creep speed control  Bosch Rexroth AG I RE 00845/04. • The extension velocity can be varied independently of the load by means of an electrical limit switch by cutting in a flow control valve. A 4/2 directional valve is used to control a hydraulic cylinder. In the following Project 19 you can impart knowledge of a velocity control. pressure intensification occurs on the piston rod side. For his documentation. The return stroke is to be performed as fast as possible.1 Practical example: Production line Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet of velocity controls (specialist qualification) • Handling of hydraulic components in line with functional needs 19 .Project 19: Rapid speed / creep speed control  Bosch Rexroth AG I RE 00845/04.07 Project definition At the end of a production line. To achieve shorter cycle times. Due to changing workpiece weights. the customer wishes to obtain a travel/time diagram in addition to a hydraulic circuit diagram and a parts list. workpieces are to be lifted from a conveyor belt and put down on a pallet. 19. the residual stroke is to be performed independently of loads at strongly reduced velocity. fast motion sequences are required. Fig. The lifting movement is to be performed using a hydraulic cylinder. examining the technical data sheet for velocity controls. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? Notes 19 . • Executing: Set-up of the hydraulic control on the training system and preparation of a travel/time diagram. among others. • Deciding: Preparation of a schematic diagram sketch and selection of components.Project 19: Rapid speed / creep speed control  Bosch Rexroth AG I RE 00845/04. • Planning: Planning and organizing the customer order.07 Project steps • Informing: Accepting and understanding the order. among others. through discussions with the customer. by. Project 19: Rapid speed / creep speed control  Bosch Rexroth AG I RE 00845/04.2 Hydraulic circuit diagram: Rapid speed advance circuit .07 Hydraulic circuit diagram Item 0.1 Item 1.4 Item 1.1 Item 0.3 Item 1. 19.2 Item 1.2 Item 1.0 Item 0.3 Measuring glass Power unit limit 19 Fig. Project 19: Rapid speed / creep speed control  Bosch Rexroth AG I RE 00845/04.07 Electrical circuit diagram red red black blue black blue Control 4/2 directional valve Extension Rapid speed -Hydraulic cylinder- Note on sensor B1/B2 Blue – red – black = plug colors Fig. 19.3 Wiring diagram for hydraulic circuit diagram Fig. 19.2 19 Project 19: Rapid speed / creep speed control  Bosch Rexroth AG I RE 00845/04.07 Component selection with parts list Item Qty 1.0 1 Double-acting cylinder with single-sided piston rod ZY 1.3 1.1 - 1.2 2 4/2 directional valve with solenoid actuation, spring return DW 3E 1.3 1 Direct operated pressure relief valve, the cracking pressure can be adjusted by means of a spring DD 1.1 1 2-flow control valve, adjustable, for one direction of flow, largely independent of viscostiy and pressure differential, with by-pass check valve DF 3 2 Distributor plate with four ports DZ 4.1 3 Pressure gauge with hose and quick release coupling without check valve DZ 1.4 3 Hose with quick release coupling with check valve DZ 25 Hose VSK 1 1.4 0.1 - 0.3 Component designation Type designation Symbol red B1/B2 2 Limit switch, inductive black DE 2 blue Table 19.1 Parts list for hydraulic circuit diagram Fig. 19.2 19 Project 19: Rapid speed / creep speed control  Bosch Rexroth AG I RE 00845/04.07 Connection block Measuring glass Component arrangement D Note: In the case of connection elements marked with “D”, the components can be connected directly with each other. Fig. 19.4 Recommended component arrangement with component designation for parts list Table 19.1 and hydraulic circuit diagram Fig. 19.2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. Also the grid arrangement is Rexroth-specific and adapted for use on the training system. Notes 19 Project 19: Rapid speed / creep speed control  Bosch Rexroth AG I RE 00845/04.07 Safety notes To ensure the operability of plant and machinery, and consequently to allow the recognition of potential risks, safety regulations must be observed before and during the execution of the order. Relevant sources of regulations are given in the introduction of the present manual. Warning Caution If work on electrohydraulic components is carried out improperly, risks of injury and a safety risk can arise during operation of the system, including danger to life. Before starting work on the training system, check that the electrical ON/ OFF switch on the hydraulic power unit is pressed in, i.e. that the system is switched off. Check on the system pressure gauge that the system is depressurized. Hydraulic systems can store pressure energy when at rest. It can cause injury when the system is opened. Execution of the order Set up the controls as described in the following: 1. Mount the components required according to parts list Table 19.1 in a clearly arranged form on the training system according to the prepared circuit diagram. Connect the hydraulic control according to hydraulic circuit diagram Fig. 19.2 by means of hoses. For connections, to which pressure gauges with minimess line DZ 1.4 are to be connected, use hydraulic hoses DZ 25. Hand-tighten the pressure gauge measuring lines at the relevant minimess connection of the hydraulic hose. The correct and proper fit of the component connections with hoses can be checked by slightly turning the hoses. Warning Caution Make sure that all ports - in this case also minimess lines - pipes and hoses are connected or that the ports are blocked with plug screws or protective caps. Leakage oil can drop through open ports on the floor and cause a risk of slipping. Before commissioning the hydraulic control, i.e. before switching the hydraulic pump on, check, whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open. Wire the electrical control according to wiring diagram Fig. 19.3. Position limit switches B1 and B2 so that the change-over takes place in the middle of the total stroke. 2. Switch the hydraulic pump on and inspect the set up control for leakage. No pressure gauge may indicate a pressure. Set the system pressure on pressure relief valve Item 1.3 to 50 bar plus one turn. 19 Project 19: Rapid speed / creep speed control  Bosch Rexroth AG I RE 00845/04.07 3. Set flow control valve Item 1.4 to scale positio. 1.0. Extend hydraulic cylinder Item 1.0 by actuating push-button S2. 4/2 directional valve Item 1.2 is operated by limit switch B1 and the flow is fed to the tank via flow control valve Item 1.4. When limit switch B2 is reached, 4/2 directional valves Items 1.1 and 1.2 are switched again to the rest position and the cylinder retracts. Enter the retraction time of the piston and the pressures M3 and M2 in Table 19.2. Enter the extension time over the entire stroke and pressures M2 and M3 (during operation at reduced velocity) in Table 19.2. Release push-button S2. This causes the piston of hydraulic cylinder Item 1.0 to retract again. Enter the retraction time of the piston and pressures M3 and M2 in Table 19.2. 4. Set flow control valve Item 1.4 to scale position 1.5 and enter the measuring results in Table 19.2 as described under point 3. Caution After having completed the practical work on the training system, switch the pump off! No pressure gauge may indicate a pressure! Open the throttle check valve. Measured values Flow control valve scale position Hydraulic cylinder Rapid speed Advance Return stroke 1.0 1.5 M3 p bar 7 6 M2 p bar 9 9 Time t s <1 <1 M3 p bar 50 50 M2 p bar 80 80 Time t s 23 12 M3 p bar 19 19 M2 p bar 38 38 Time t s <1 <1 Table 19.2 Measured values from the project order The values were measured at an oil temperature of approx. 20 °C. The values measured by the trainees can deviate by 10 %. 19 Project 19: Rapid speed / creep speed control 10 Bosch Rexroth AG I RE 00845/04.07 For information, please find below the graphical representation of the piston velocity of the single-rod cylinder. Table 19.3 shows a function sequence chart commonly used in practice. Travel y x Rapid speed Advance t Time Return stroke Diagram 19.1 Travel/time diagram Item 1.1 Item 1.2 → → Rapid speed lifting 1 0 → Advance lifting 1 1 ← ← Lowering 0 0 Table 19.3 Function chart Legend: 0 not operated 1 operated Evaluating the work results with regard to the customer requirement • With a rapid speed advance circuit, the piston of a hydraulic cylinder extends with maximum pump flow without throttling. • With the help of an electrical limit switch, the extension velocity can be adjusted - controlled by a directional valve - independently of the load by means of a flow control valve. • The return stroke of the piston is performed with the maximum pump flow. • When the flow is throttled at the piston rod side, pressure intensification occurs during extending. 19 • Circulation helps to save electric power. if the flow previously discharged via a 4/2 directional valve is directed to the 4/3 directional valve. only a small pressure builds up in the hydraulic pump. Based on the control set up on the training system the trainee is to implement a circuit for circulating the pump displacement. more energy is consumed. When no hydraulic energy is required. i. to the circulation position. Notes on detailed technical information about the pump control: • The Hydraulic Trainer Volume 1/Bosch Rexroth AG Basic principles and components • Technical data sheet RE 10089 Fixed displacement pump/external gear pump 20 .e. A hydraulic cylinder is to be controlled by means of a 4/3 directional valve with circulation position. However. • The circulation control reduces wear of the hydraulic pump. the system pressure can only build up. In a further control circuit. In the project order the trainee is to work out the possibility of directing the pump flow via a circulation valve. If the hydraulic pump displaces hydraulic fluid via the pressure relief valve while the hydraulic cylinder is at a standstill. but can also result in lubrication problems. the fluid is not excessively heated and its service life extended.Project 20: Valve circulation control  Bosch Rexroth AG I RE 00845/04. the hydraulic cylinder is to be controlled by means of a 4/3 directional valve with blocked central position.07 Project 20: Valve circulation control Project/trainer information A circulation control for a fixed displacement pump can be used to prevent the hydraulic fluid from excessive overheating. In the following Project 20 you can impart knowledge of a valve circulation control. Overheating would not only lead to premature wear of the hydraulic fluid. the following knowledge is to be gained through the project task: • When the pump flow circulates. • When the hydraulic fluid circulates. the directional valve is brought to the central position. in this case. In a practice-oriented experiment set-up on the training system. 20. apart from the hydraulic circuit diagram and the parts list. To spare the hydraulic pump. a scissors lift it used for lifting and lowering pallets. The customer wishes to obtain several solution proposals and for his documentation. In order that the hydraulic cylinder can be stopped at any position. a comparison of the proposed solutions.1 Practical example: Scissors lift Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the technical data sheet of fixed displacement pump (specialist qualification) • Handling of hydraulic components in line with functional needs 20 . a solution is to be provided.07 Project definition For the assembly of heavy hydraulic control blocks.Project 20: Valve circulation control  Bosch Rexroth AG I RE 00845/04. with which the pump flow is directed at zero pressure to the tank when the hydraulic cylinder is not operated. Fig. a 4/3 directional valve with blocked central position is used. and in particular with the section of symbols. among others. Acquisition of measured values and preparation of a comparison table. through dealing with the technical data sheet for the 4/3 directional valve.Project 20: Valve circulation control  Bosch Rexroth AG I RE 00845/04. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? Notes 20 . • Deciding: Preparation of a schematic diagram sketch and selection of components. through discussions with the customer. • Executing: Set-up of the hydraulic control on the training system. • Planning: Planning and organizing the customer order. among others. RE 23178.07 Project steps • Informing: Accepting and understanding the order. 07 Hydraulic circuit diagram 1 Item 1.1 Item 1.4 Measuring glass Power unit limit 20 Fig.Project 20: Valve circulation control  Bosch Rexroth AG I RE 00845/04.3 Item 1. 20.0 Item 0.1 Item 0.2 Hydraulic circuit diagram: Pressureless circulation using a 4/3 directional valve .2 Item 0. 20. 20.Project 20: Valve circulation control  Bosch Rexroth AG I RE 00845/04.3 Wiring diagram for hdraulic circuit diagram Fig.2 .07 Electrical circuit diagram Circulation Control 4/3 directional valve Extension Retraction -Single-rod cylinder- 20 Fig. 4 Hydraulic circuit diagram: Pressureless circulation using an additional 4/2 directional valve .0 Item 0.3 Item 0.1 Item 1.2 Item 0.3 Item 1.1 Item 1.07 Hydraulic circuit diagram 2 Item 1.Project 20: Valve circulation control  Bosch Rexroth AG I RE 00845/04.4 Measuring glass Power unit limit 20 Fig. 20. Project 20: Valve circulation control  Bosch Rexroth AG I RE 00845/04. 20. 20.5 Wiring diagram for hydraulic circuit diagram Fig.4 .07 Electrical circuit diagram Circulation Control 4/3 directional valve .4/2 directional valve Retraction Extension Circulation -Single-rod cylinder- 20 Fig. B DW 4E 1.3 Component designation Type designation Symbol Table 20.1 Parts list for hydraulic circuit diagram Fig. A. the cracking pressure can be adjusted by means of a spring DD 1.2 1 4/3 directional valve with direct actuation by two solenoids.0 1 Double-acting cylinder with single-sided piston rod ZY 1.T.2 and 20.1 .0.4 3 Hose with quick release coupling with check valve DZ 25 Hose VSK 1 1.4 20 .07 Component selection with parts list Item Qty 1. spring centering of the central position and central position P .4 1 Direct operated pressure relief valve.1 1 Distributor plate with four ports DZ 4. 20. spring centering of the central position and central position P. spring return DW 3E 1. A.Project 20: Valve circulation control  Bosch Rexroth AG I RE 00845/04.3 1 4/3 directional valve with direct actuation by two solenoids. B DW 13E 1.1 3 Pressure gauge with hose and quick release coupling without check valve DZ 1.3 1 4/2 directional valve with solenoid actuation.1 0. T. 2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. Notes 20 .Project 20: Valve circulation control  Bosch Rexroth AG I RE 00845/04. the components can be connected directly with each other.07 Connection block Measuring glass Component arrangement 1 D Note: In the case of connection elements marked with “D”. Fig. 20. Also the grid arrangement is Rexroth-specific and adapted for use on the training system.6 Recommended component arrangement with component designation for parts list Table 20.1 and hydraulic circuit diagram Fig. 20. Project 20: Valve circulation control 10 Bosch Rexroth AG I RE 00845/04.7 Recommended component arrangement with component designation for parts list Table 20. 20.4 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. Fig. the components can be connected directly with each other.07 Connection block Measuring glass Component arrangement D Note: In the case of connection elements marked with “D”. Notes 20 . Also the grid arrangement is Rexroth-specific and adapted for use on the training system. 20.1 and hydraulic circuit diagram Fig. Before commissioning the hydraulic control.4 are to be connected. The correct and proper fit of the component connections with hoses can be checked by slightly turning the hoses. Warning Caution Make sure that all ports .3. 3. to which pressure gauges with minimess line DZ 1. use hydraulic hoses DZ 25.e. No pressure gauge may indicate a pressure. Before starting work on the training system. Check on the system pressure gauge that the system is depressurized.2 by means of hoses. It can cause injury when the system is opened.07 Safety notes To ensure the operability of plant and machinery. Wire the electrical control according to wiring diagram 20. For connections. To make clear that in the central position the total amount of fluid flows through 4/3 directional valve Item 1. that the system is switched off. including danger to life. Leakage oil can drop through open ports on the floor and cause a risk of slipping. safety regulations must be observed before and during the execution of the order.1. 2. before switching the hydraulic pump on. Hydraulic systems can store pressure energy when at rest.pipes and hoses are connected or that the ports are blocked with plug screws or protective caps.Project 20: Valve circulation control 11 Bosch Rexroth AG I RE 00845/04. check. 20 .4 to 50 bar plus one turn.in this case also minimess lines . Relevant sources of regulations are given in the introduction of the present manual. Mount the components required according to parts list Table 20. i. check that the electrical ON/ OFF switch on the hydraulic power unit is pressed in. Set the system pressure on pressure relief valve Item 1. whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open. risks of injury and a safety risk can arise during operation of the system. port T of directional valve Item 1.1 in a clearly arranged form on the training system according to the prepared circuit diagram. and consequently to allow the recognition of potential risks. i. Warning Caution If work on electrohydraulic components is carried out improperly. The system pressure can only be adjusted while the cylinder is at its end position.e. Switch the hydraulic pump on and inspect the set up control for leakage. 20. Execution of the order Set up the controls as described in the following: 1. Connect the hydraulic control according to hydraulic circuit diagram Fig.1 can be connected to the measuring glass (option). Hand-tighten the pressure gauge measuring lines at the relevant minimess connection of the hydraulic hose. e. The system pressure can only be adjusted while the cylinder is at its end position.in this case also minimess lines .2 using push-buttons S2 and S4.4 by means of hoses. Before making any conversion for further order processing.3 when directional valves Item 1. Mount the components required according to parts list Table 20. Measure and note pressure M1 in the relevant end position of hydraulic cylinder Item 1.0 while directional valve Item 1. Warning Caution Make sure that all ports . 20. directional valve Item 1. i. before switching the hydraulic pump on.0 can be traversed with the help of push-buttons S2 and S4 as described in the project task.4 to 50 bar plus one turn.3 must be operated before by means of push-button S3. Hydraulic cylinder Item 1. Note pressure M1 in the relevant end position of hydraulic cylinder Item 1. Set the system pressure on pressure relief valve Item 1. switch the hydraulic pump off! No pressure gauge may indicate a pressure! Caution Task 2 Circulation 5. check. 20. to which pressure gauges with minimess line DZ 1. Hand-tighten the pressure gauge measuring lines at the relevant minimess connection of the hydraulic hose. Switch the hydraulic pump on and inspect the set up control for leakage.2 and Item 1. switch the pump off! No pressure gauge may indicate a pressure! Open the throttle check valve.3 are not operated.0 (S2.1 in a clearly arranged form on the training system according to the prepared circuit diagram. 6.5. Before commissioning the hydraulic control. Caution After having completed the practical work on the training system.3 can be connected directly to the measuring glass (option). Leakage oil can drop through open ports on the floor and cause a risk of slipping. Connect the hydraulic control according to hydraulic circuit diagram Fig. To provide more clarity that the entire flow is fed directly to the tank via 4/2 directional valve Item 1.4 are to be connected. use hydraulic hoses DZ 25.1 is in its central position. No pressure gauge may indicate a pressure.07 Flow in central position 4.3 is not operated. Wire the electrical control according to wiring diagram Fig.Project 20: Valve circulation control Task 1 12 Bosch Rexroth AG I RE 00845/04. For connections.0 can be controlled via directional valve Item 1. S4 operated) while directional valve Item 1.pipes and hoses are connected or that the ports are blocked with plug screws or protective caps. whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open. 7. Hydraulic cylinder Item 1. 20 . port T of directional valve Item 1. To this end. The correct and proper fit of the component connections with hoses can be checked by slightly turning the hoses. 20 . • Circulation saves electric power. • Due to the circulation circuit.Project 20: Valve circulation control 13 Bosch Rexroth AG I RE 00845/04.2 Actual pressure values with different valve settings The values were measured at an oil temperature of approx. 20 °C. hydraulic fluid does not heat up excessively. The values measured by the trainees can deviate by 10 %. only a small pressure builds up in the hydraulic pump. and the service life of the fluid is extended.07 Measured values Task 1 M1 p in bar Circulation Task 2 p in bar p in bar 0 8 0 8 a 50 a 50 b 50 b 50 Cylinder end position Table 20. • The circulation circuit reduces wear of the hydraulic pump. Evaluating the work results with regard to the customer requirement • When the pump displacement is circulated. Project 20: Valve circulation control 14 Bosch Rexroth AG I RE 00845/04.07 Notes 20 . 21 . multi-meters. function charts. the following knowledge is to be gained in the course of the project task: • For commissioning. commissioning. • Improper mounting can significantly reduce the service life of hydraulic components and leads to costly downtimes. system-related machine documents such as circuit diagrams. maintenance. but also operators) is to keep systems in operation. • can take the necessary measures to eliminate risks. A specialist is. condition monitoring and the determination of machine operating schedules form the basis for active maintenance. oil-soaked cloths and paper must be properly disposed of. flowmeters. • Contamination is by far the most common cause of faults in hydraulic systems. and their accessories. repair Project/trainer information A long service life and functional reliability of hydraulic systems and their components depend on proper handling. Here. The persons involved must be able to read and interpret not only hydraulic circuit diagrams. maintenance  Bosch Rexroth AG I RE 00845/04. etc. The main task of responsible persons (fitters. system parameters and operating instructions are required. and inspections may only be carried out by trained and instructed personnel having a specific knowledge of hydraulics. Important information can also be found in the technical data sheets for components. • can recognize possible hazards. troubleshooting. Maintenance includes measures for maintaining the desired condition of a system.Project 21: Commissioning. Repair and servicing staff must consider the entire system in examinations. troubleshooting. Environmental protection also plays an important role. Repairs are measures for restoring the desired condition of a system. Not only for the engineering. The observation of system-specific installation and operating notes of the supplier guarantee trouble-free operation. but also electrical circuit diagrams. • has the required knowledge with regard to repairs and assembly. due to his/her technical training and experience. On the basis of a practice-oriented experiment set-up. maintenance. Troubleshooting in modern controls requires the skillful handling of measuring and diagnosis devices such as pressure gauges. According to DIN 31051 maintenance includes the sum of all measures for maintaining and restoring technical systems. who. regulations and safety rules must be observed. Inspection is an assessment of the actual condition of a system. A precondition for meeting this requirement cost-efficiently is profound knowledge. parts list. Commissioning is the provision of an operable system. has sufficient knowledge and is sufficiently familiar with relevant regulations that he/she: • can assess the work assigned to him/her. In the project order the trainee is to work out commissioning of a hydraulic control and the procedure for component adjustments. inspection.07 Project 21: Commissioning. Repairs. For example. especially for maintenance personnel. power units. but also for everyday handling of modern hydraulic systems. is hydraulically pre-loaded by a 4/2 directional valve connected in parallel. maintenance  Bosch Rexroth AG I RE 00845/04.5 l/min). • Preventive maintenance and inspection reduce failures of systems and prolong the service life of components. 5 s. On the basis of the complex control set up on the training stand. pressure. and flow control valves • Technical data sheet RE 07100-B Hydraulic cylinders/operating instructions (exemplarily for notes on: commissioning. Notes on detailed technical information about the project order: • The Hydraulic Trainer Volume 1/Bosch Rexroth AG Basic principles and components • Technical data sheets for all hydraulic components listed such as directional. and then the hydraulic motor is to rotate uniformly. The lifting time is to be adjusted by means of a throttle and take approx. A hydraulic motor (set to 1. Controlled by a 4/3 directional valve. • Target-oriented communication simplifies the analysis of faults. inspection. which is to rotate independently of the load by using a flow control valve. troubleshooting. the trainee is to work out commissioning of an electrohydraulic control and the order of adjusting the individual components. a hydraulic cylinder is to lift a load.Project 21: Commissioning.07 • An indispensable tool for targeted fault analyses is the understanding of the function and operating principle of all hydraulic components in the system. Controlled by an electrical push-button. maintenance. repair) • General product information on hydraulic products Technical data sheet RE 07008 21 . first the cylinder is to lift the load. Before being machined. A flow chart is to provide information about assumed faults (hydraulic motor does not rotate). Fig. 21. the workpiece is to be lifted by a lifting cylinder to the machining position.07 Project definition On a machine tool. In addition. which solenoids are to be switched for the individual process sequences. which is powered by a hydraulic motor. he requires a simple diagram showing the function sequence. To be able to advise the electrician. a workpiece is to be machined by a tool. troubleshooting. The customer wishes to obtain the required machine documents such as hydraulic and electrical circuit diagrams with parts lists. he wishes to obtain notes on preventive maintenance and inspection. maintenance  Bosch Rexroth AG I RE 00845/04. system parameters and commissioning instructions such as the order of adjustment of hydraulic components for documentation purposes.1 Practical example: Machine tool control (not project-related) Principle structure of a complex machine tool with components covering all technologies Project tasks • Independent understanding of the task and its putting into practice using hydraulic control technology • Planning and organizing the customer requirement (core qualification) • Analyzing the required technical documents (specialist qualification) • Handling of hydraulic components in line with functional needs 21 .Project 21: Commissioning. Project 21: Commissioning. troubleshooting. among others. • Executing: Set-up of the hydraulic control on the training system. through discussions with the customer. • Planning: Planning and organizing the customer order. among others. Acquisition of measured values and preparation of the technical documentation requested by the customer. maintenance  Bosch Rexroth AG I RE 00845/04.07 Project steps • Informing: Accepting and understanding the order. by dealing intensively with technical data sheets. • Deciding: Preparation of a schematic diagram sketch and selection of components. • Checking: Are all customer requirements met? • Evaluating: Are there further possibilities of meeting the customer requirement or simpler ways of project execution? Have unforeseeable problems occurred? Notes 21 . maintenance  Bosch Rexroth AG I RE 00845/04.07 Notes 21 . troubleshooting.Project 21: Commissioning. troubleshooting.0 Item 0.5 l/min Item 1.4 Item 2.2 Item 2.Project 21: Commissioning.0 Item 0.3 Item 2.2 Item 0. maintenance  Bosch Rexroth AG I RE 00845/04. 21.3 Set to 1.1 Set to text = 5 sec Item 2.1 Item 0.2 Hydraulic circuit diagram: Machine tool control 21 .07 Hydraulic circuit diagram Item 1.3 Item 1.1 Item 1.2 Measuring glass Power unit limit Fig. troubleshooting.4/2 directional valve Extension Retraction Lifting Lowering Fig. 21.Project 21: Commissioning. maintenance  Bosch Rexroth AG I RE 00845/04.3 Wiring diagram for the machine control -Single-rod cylinder- Rotation -Hydraulic motor- 21 .07 Electrical circuit diagram Stop Control 4/3 directional valve . 3 1 Throttle valve.1 1 4/3 directional valve with direct actuation by two solenoids. spring centering of the central position and central position P. 21. B DW 13E 1.Project 21: Commissioning. troubleshooting.1 2.4 hose Table 21. with by-pass check valve DF 3 3 Distributor plate with four ports DZ 4. adjustable.2 Type designation VSK 1 Symbol 21 . T. spring return DW 3E 3 2-way flow control valve.1 Parts list for hydraulic circuit diagram Fig.0 3 Fixed displacement motor with external leakage oil line and two directions of rotation DM 8N 2.3 2 Direct operated pressure relief valve. for one direction of flow. the cracking pressure can be adjusted by means of a spring DD 1.1 1 4/2 directional valve with solenoid actuation. A.4 4 Hose with quick release coupling with check valve DZ 25.0.07 Component selection with parts list Item Qty Component designation 1.1 4 Pressure gauge with hose and quick release coupling without check valve DZ 1. largely independent of viscosity and pressure differential.1 1. adjustable.2 0. maintenance  Bosch Rexroth AG I RE 00845/04.0 1 Double-acting cylinder with singlesided piston rod with load 1.1 . adjustable DF 1.2 2.2/2. 1 and hydraulic circuit diagram Fig.07 Connection block Measuring glass Component arrangement D Note: In the case of connection elements marked with “D”.Project 21: Commissioning. Fig. 21. troubleshooting. maintenance  Bosch Rexroth AG I RE 00845/04.4 Recommended component arrangement with component designation for parts list Table 21. 21.2 Note: The designations of components in the parts list and the component arrangement are Rexrothspecific designations. the components can be connected directly with each other. 21 . Also the grid arrangement is Rexroth-specific and adapted for use on the training system. It can cause injury when the system is opened. Check on the system pressure gauge that the system is depressurized. and consequently to allow the recognition of potential risks. use hydraulic hoses DZ 25. to which pressure gauges with minimess line DZ 1. Wire the electrical control according to wiring diagram Fig. Warning Caution Make sure that all ports . check. check that the electrical ON/ OFF switch on the hydraulic power unit is pressed in. For connections. 21. Before commissioning the hydraulic control. Relevant sources of regulations are given in the introduction of the present manual.e. risks of injury and a safety risk can arise during operation of the system.2 by means of hoses. 21. whether all pressure control valves are set to minimum pressure (spring unloaded) and all throttle valves are open. troubleshooting. i. safety regulations must be observed before and during the execution of the order.2 to 50 bar plus one turn. Warning Caution If work on electrohydraulic components is carried out improperly. 2. Switch the hydraulic pump on and inspect the set up control for leakage. The correct and proper fit of the component connections with hoses can be checked by slightly turning the hoses. 21 . Leakage oil can drop through open ports on the floor and cause a risk of slipping.4 are to be connected. Hydraulic systems can store pressure energy when at rest.1 in a clearly arranged form on the training system according to the prepared circuit diagram. Execution of the order Set up the control as described below: 1. Hand-tighten the pressure gauge measuring lines at the relevant minimess connection of the hydraulic hose.pipes and hoses are connected or that the ports are blocked with plug screws or protective caps. Set the system pressure on pressure relief valve Item 1.in this case also minimess lines .07 Safety notes To ensure the operability of plant and machinery. i. Connect the hydraulic control according to hydraulic circuit diagram Fig.e. before switching the hydraulic pump on. maintenance 10 Bosch Rexroth AG I RE 00845/04. No pressure gauge may indicate a pressure.Project 21: Commissioning. Before starting work on the training system.3. that the system is switched off. Mount the components required according to parts list Table 21. including danger to life. Measure pressure M1.2.2.1 by means of electrical push-buttons S2 (extending/lifting) and S4 (retracting/lowering) to traverse hydraulic cylinder Item 1. The values measured by the trainees can deviate by 10 %. troubleshooting. set pressure relief valve Item 2. While the hydraulic motor is rotating. Acquire pressures M1 and M4 while the hydraulic motor is rotating and enter the values in system parameter sheet Table 21.3 to a hydraulic pre-load pressure of 20 bar.5 l/min can be measured by means of the measuring glass. adjust flow control valve Item 2.0.3. Upon the activation of 4/2 directional valve Item 2. For system-inherent reasons. 20 °C. maintenance 11 Bosch Rexroth AG I RE 00845/04. 1. Commissioning: Hydraulic motor 4. the motor only rotates clockwise! Caution After having completed practical work on the training system switch the hydraulic pump off! No pressure gauge may indicate a pressure! Open the throttle check valve.2 System parameters of machine tool control The values were measured at an oil temperature of approx. 21 .Project 21: Commissioning. After having adjusted the speed of the hydraulic motor while the latter was rotating.2 so that a flow of approx. Activate 4/3 directional valve Item 1. The lifting velocity of approx.07 Commissioning: Lifting cylinder 3.0 rotates clockwise. Measured values Actuator Lifting cylinder Lifting cylinder Hydraulic motor Function Lifting Lowering Rotating Measuring point Value in bar M1 48 M2 0 M3 5 M1 48 M2 47 M3 30 M1 48 M4 20 Table 21. 5 s is set on throttle valve Item 1.1 by means of electrical push-button S3 hydraulic motor Item 2. M2 and M3 during operation of the lifting cylinder and enter the values in system parameter sheet Table 21. troubleshooting.3 Function sequence/machine tool control Legend: 1 Valve spool energized 0 Valve spool not energized 21 .Project 21: Commissioning. maintenance 12 Bosch Rexroth AG I RE 00845/04.a Y1.07 For a simple representation of the function sequence of an electrohydraulic control. Travel/increment or travel/time diagrams can be used additionally for representing movements of more complex controls.b Y2 Lifting 1 0 0 Lowering 0 1 0 Holding 0 0 0 Rotating 0 0 1 Stop 0 0 0 Table 21. Valve solenoid Lifting cylinder Hydraulic motor Y1. function charts as shown below are used in practice. the operator actuates push-button S2 to lift the workpiece by means of lifting cylinder Item 1.5 l/min and pre-loading valve Item 2. Lifting time text in 5 s. • Chips produced during machining are transported from the operating range of the machine tool by a chip conveyor.Project 21: Commissioning. To this end.0 to the machining position (on sight). • After completion of the machining process. correct position no →→→ Is the valve spool jammed? no →→→ Check settings yes Valve Y2 activated ↓ ↓ Pump pressure available? yes yes yes Flow control valve Item 2. maintenance 13 Bosch Rexroth AG I RE 00845/04. Sequence chart for troubleshooting Workpiece correctly put down? ↓ ↓ yes no →→→ →→→ System pressure available? Check loading Are faults/fault messages present such as: filter. load-independent rotating of the hydraulic motor by means of flow control valve Item 2.2 open? ↓ yes ↓ Note: Possibly mechanical fault of the hydraulic motor? ↑ ↑ Load pressure too high? yes →→→ Check DB valve Item 2.3/20 bar 21 . with a check made by sensors to guarantee compliance with safety regulations.07 Machine tool control Example of fault: Hydraulic motor/machining motor does not rotate Process sequence • The machine operator loads the workpieces at a defined position.3 set to 20 bar. oil level. troubleshooting. • The machine operator closes the door to the working range of the machine tool. • After the workpiece position was checked. • Machining of the workpiece is accomplished with hydraulic motor Item 2. the machine operator actuates push-button S3 (on sight).0 at end position? ↓ ↓ no →→→ Check and. the machine operator stops the hydraulic motor by actuating push-button S5 and then moves the workpiece to the basic position for the hydraulic cylinder by operating push-button S4. Constant. temperature? no →→→ Is the pump running? no →→→ Check motor no →→→ Check pump controller →→→ Check by activating emergency stop ↓ yes ↓ ↓ ↓ Lifting cylinder Item 1. if required.2 which is set to qV = 1.0 (rotating clockwise). troubleshooting. It must be ensured that the permissible maximum cleanliness class to ISO 4406 KL. • Adjust the rotary speed/close flow control valve/measure the flow by means of the measuring glass/1. i. • Check of hydraulic fluid for fluid level and appearance 21 .Inspection . wear.e..2 to 20 bar. Question 5: Into which areas is maintenance subdivided? • DIN 31051 classifies maintenance in the following areas: Maintenance . damage. maintenance 14 Bosch Rexroth AG I RE 00845/04.Project 21: Commissioning. The notes on waste disposal given in the safety data sheet of the hydraulic fluid must be observed.5 l/min.3 • Measure the operating pressures and enter them in the system parameter table • Check the rotating function of the hydraulic motor. • Check the electrical control for function • Check the set-up of the hydraulic control • Set the pressure relief valves to minimum pressure/spring unloaded • Adjust flow control valves to adequate flow • Switch the hydraulic pump on/Leakages?/Direction of motor rotation OK?/No excessive pressures in the system? • Set the system pressure to 50 bar plus one turn/DB valve Item 1.2 • Check the LIFTING/LOWERING function of the lifting cylinder/push-buttons S4 . .07 Questions Question 1: Name the systematic working steps during commissioning and for adjusting the electrohydraulic control. Question 4: How should the hydraulic fluid be disposed of? • The fluids must be disposed off in accordance with environmental regulations. • Enter the machining pressure of the hydraulic motor in the system parameter table Question 2: Which 6 machine documents are indispensable for electrohydraulic systems? • Hydraulic circuit diagram/with parts list • Wiring diagram • Function chart • Operating instructions • Machine key data/system parameters • Measurement report of initial commissioning Question 3: Why should a hydraulic system be flushed prior to initial commissioning? • The flushing process removes dirt particles from the individual components such as pipes.Repair Question 6: Which work (measures) must be carried out during an inspection? • Check of set operating values • Visual inspection of the complete system for external leakage. the contaminated fluid must be made available to approved recycling companies in suitable containers for disposal.. • Set the pre-loading valve/DB valve Item 2.S2 • Adjust the lifting time to 5 s/throttle Item 1. 21/18/15 is not exceeded for the entire system. loose • Spring broken in hydraulic element. does not work • Throttle bore clogged Question 9: Name a systematic order for the localization and elimination of faults. maintenance 15 Bosch Rexroth AG I RE 00845/04. if required • Replacing hydraulic hoses at given intervals Question 8: Which of the following faults are causes for malfunction that can be traced back to improper installation and which faults occur on running systems? • Incorrect directional valve installed • Electric motor incorrectly connected • Contaminated hydraulic fluid • Hydraulic hose improperly connected • Wear of hydraulic seals • Filter clogged • Cable break at the connection of the solenoid • Pressure switch does not switch • Hydraulic component does not operate due to a broken spring • Throttle bore clogged on the pilot part Improper installation during initial commissioning: • Incorrect directional valve installed • Electric motor incorrectly connected • Hydraulic hose improperly connected • Pressure switch not set to the correct value Faults on running systems: • Contaminated hydraulic fluid • Wear of seals • Filter clogged • Solenoid cable break • Limit switch does not switch. troubleshooting.Project 21: Commissioning.07 Question 7: Which work (measures) are to be carried out during maintenance? • Changing the filter inserts • Checking or changing the hydraulic fluid • Cleaning the inside of the tank. • Recognizing faults on the system and their effect • Analyzing the cause of fault • Planning of how to eliminate the fault • Proper elimination of the fault • Re-commissioning the system • Documenting the fault and its elimination 21 . Project 21: Commissioning. • An important precondition for target-oriented troubleshooting is the knowledge of the function and the operating principle of all hydraulic components. maintenance 16 Bosch Rexroth AG I RE 00845/04. parts list. • Preventive maintenance and repair reduce system failures and prolong the service life of components. • Improper installation can shorten the service life of hydraulic components. system parameters and operating instructions. 21 . • Contamination is the most common cause of faults in hydraulic systems. function charts.07 Evaluating the work results with regard to the customer requirement • For correct commissioning. troubleshooting. system-related machine documents are required such as circuit diagrams. troubleshooting.07 Notes 21 .Project 21: Commissioning. maintenance 17 Bosch Rexroth AG I RE 00845/04. . 05 Ihre Sprache? – Siehe Rückseite! Your language? – See back page! Votre langue ? – Voir au dos ! La vostra lingua? – Vedi retro! Kohdekielet? – Katso takankatta! ¿Su idioma? – ¡Vea al dorso! Uw taal? – Zie achterzijde! Ditt sprak? – Se omslagets baksida! O seu idioma? – Consulte a contracapa! Dit sprog? – Se bagside! Η γλώσσα σα.General product information on hydraulic products DE EN FR IT FI ES NL SV PT DA EL RE 07008/02. – Βλέπε πίσω πλευρά! 1/32 . 2 What you need to know about this product information 4 1.1 How to handle pressure fluids safely 13 5.2 Safety labelling on the hydraulic product 7 3.2 Ambient conditions 11 What you need to know about pressure fluids 13 5.2 Functions and effectiveness 13 5.5 Topping up/refilling 14 Construction and mode of operation of a hydraulic system 15 6.1 Information about pressure fluids 11 4.2/32 Bosch Rexroth AG Hydraulics Contents 1 2 3 4 5 6 General product information Page Important basic information 4 1.3 Viscosity 13 5.1 What to do in an emergency 7 3. guarantee.5 General ancillary dangers and protective measures when operating hydraulic products 9 Technical data and ambient conditions 11 4.1 Definitions of terms 15 6.3 Liability.2 Seals. warranty 6 2.1 Scope of delivery and responsibilities of Bosch Rexroth 5 2.2 Schematic 15 6.4 Leakage fluid 14 5.1 Conventions used in this product information 4 1.3 Proper use 7 3.3 The contents of this product information 4 Scope of delivery and responsibilities 5 2.4 Copyright 6 Important basic safety instructions 7 3.4 Requirements for personnel. duty of care 8 3.3 Safety concept 15 7 Moving hydraulic units/components 16 8 Storage and longer standstills 16 8.subsequent bringing into use after storage 16 8.1 Hydraulic systems . hoses and hose lines 17 RE 07008 .2 Responsibilities of the plant operator 5 2. 1 Safety advice for assembly and bringing into first use 18 9.2 Safety devices relating to hydraulic pressure accumulators 30 Hydraulic systems 31 14.RE 07008 General product information Hydraulics Bosch Rexroth AG Contents 9 3/32 Page Assembly and bringing into first use 18 9.3 Bringing into first use.1 General 30 13.1 What to do in the event of a fault 22 11.2 The basic approach to trouble-shooting 22 11.3 Trouble-shooting tables 23 12 13 14 Maintenance 24 12.6 Servicing pressure accumulators 29 12.1 31 Effects of leaks in the hydraulic system on the machine .7 Repair 29 General information about hydraulic pressure accumulators 30 13.2 Safety during maintenance tasks 24 12.4 Service and storage lives of hose lines 28 12.1 Definitions of terms 24 12.5 Topping up the pressure fluid 29 12. subsequent bringing into use 19 10 Operation 22 11 Trouble-shooting 22 11.3 Inspection and servicing 25 12.2 Before bringing into first use 18 9. However. standards and regulations contained in this product information refer to the versions current at the time of writing of this product information.1 Bosch Rexroth AG Hydraulics Important basic information Conventions used in this product information Cross-references are printed in italics. Specific cross-references are used to draw your attention to information that you can find in the Operating Instructions. Ø Parts lists if appropriate Ø Information about replacement parts and accessories. The Operating Instructions must be directly accessible to one of the personnel at the hydraulic product and kept readily available at all times in a place known to the personnel. IMPORTANT General product information Observing the product information and Operating Instructions Ø reduces downtimes and maintenance costs Ø increases the service life of your hydraulic products. Only if all the information contained in all parts of the three-part Operating Instructions is observed can safe operation of Rexroth hydraulic products be ensured. the Technical Datasheet Ø Part III. The contents of this product information In addition to this document.and Application-specific Operating Instructions. drawings As this product information for Rexroth hydraulic products applies in a general sense. Ø Technical data and operating limits Ø Information about bringing into (first) use and maintenance Ø Information about the mode of operation IMPORTANT Ø Layouts. please request the missing part from Bosch Rexroth. . the general Operating Instructions for the relevant class of products Ø Part II. CAUTION This symbol indicates possible danger which may lead to minor or serious injury and/or to material damage.2 RE 07008 If you do not have all three parts. some of the content may not necessarily apply to the hydraulic product you have purchased. only by strictly observing this product information and the Operating Instructions can accidents be prevented and problem-free operation of your Rexroth hydraulic product be guaranteed. The Operating Instructions must be read and understood and all its provisions observed by those responsible and by the operative personnel. WARNING This symbol indicates a threat of danger which may result in death or very serious injury if not avoided. DANGER This symbol indicates a threat of danger which will result directly in death or very serious injury if not avoided. We recommend that a record is made in writing of the employees’ familiarisation with all the relevant parts. including Ø Information about the scope of delivery Ø Safety instructions This product information applies exclusively to hydraulic products that are operated with mineral-oil-based pressure fluids. which can be obtained from the title page of this product information. The Operating Instructions contain detailed information about the product. 1. if the Operating Instructions do not expressly permit the use of other pressure fluids. The cross-references to directives.4/32 1 1. the Product. product information for Rexroth hydraulic products normally includes Operating Instructions consisting of three parts: Ø Part I. 1. This symbol indicates additional information.3 What you need to know about this product information This product information applies to the following types of hydraulic products: Ø Hydraulic components Ø Hydraulic power units Ø Hydraulic systems. 2 Special points concerning the installation of certain products A Rexroth hydraulic product is intended above all for installation in machines. 2. then the Machinery Directive applies as appropriate – including the then currently applicable amendments – in that the scope of delivery does not necessarily comply with the requirements of the Machinery Directive because the scope of delivery is intended for installation in a machine or because the scope of delivery is intended for combination with other machines into a machine or a hydraulic system. You must also observe the EU directives for the use of work equipment (Directive 89/391/EC) and the associated individual directives. If the scope of delivery is intended to be installed in a machine or system. The legislation contains minimum requirements with respect to the making available by the employer of work equipment and for the use of work equipment by employees at work. systems and power units as a part machine or a component for installation into another machine or system and is not a complete machine in the sense of the EU directive. at the time of their first introduction on to the market. dividing areas endangered by potentially explosive atmospheres into zones and specifying suitable work equipment and procedures for these areas.2. If no values are documented then it can be taken that the value is less than 70 dB(A). We recommend that the results of the hazard analysis (risk assessment) of the overall machine are taken into account in the design of the hydraulic product. IMPORTANT Bosch Rexroth points out that. It may only be used if the relevant safety datasheet from the manufacturer is available and all the measures stipulated therein have been implemented. for example. including the regulations for operating equipment requiring supervision and the obligation to produce explosion protection documentation. The bringing into use of the scope of delivery shall therefore not be permitted until the machine or system in which the scope of delivery is to be installed or of which it represents a component complies with the requirements of all relevant EU directives. In connection with this. the hydraulic product in question must be placed in a suitable collecting trough. If there is a risk of fluid leaking from the hydraulic product and contaminating water or the ground. Mineral-oil-based pressure fluid is hazardous to water and flammable. IMPORTANT For the scope of delivery and the responsibilities of Bosch Rexroth with respect to the product. 2. 2. Details of further responsibilities can be found in 3 Important basic safety instructions and in the Operating Instructions. Therefore you must always make sure that the hydraulic product is also suitable without restriction for the proposed application at the installation location. the applicable statutory regulations must be observed. For this reason. This involves. protection must be put in place that would prevent any escaping pressure fluid from igniting and the hose lines from aging prematurely.RE 07008 General product information Hydraulics Bosch Rexroth AG 5/32 2 Scope of delivery and responsibilities Installation of Rexroth hydraulic products in a machine or system may increase this value. Rexroth hydraulic products fulfil all safety requirements applicable to fluid power systems and their components. . still further directives may apply.2. especially Directive 1999/92/EC for the protection from the danger arising from potentially explosive atmospheres and their implementations in national legislation. hydraulic products comply with the requirements of all relevant EU directives and/or their implementation into national legislation in Germany. The interfaces with the overall machine and the operating conditions are also of the greatest importance.1 Scope of delivery and responsibilities of Bosch Rexroth At or above 85 dB(A).2 Responsibilities of the plant operator CAUTION If Rexroth hydraulic products are positioned in the vicinity of sources of ignition or strong radiators of heat. The functioning of the hydraulic product is also influenced by the machine or system in which it is installed. the manufacturer of the machine/system must document this. 2. A wide range of dangers can arise from the combined actions of the hydraulic product and the machine or system in which the hydraulic product is installed. you must also always observe the Operating Instructions of the overall system in which your hydraulic product is installed. the plant operator must make suitable hearing protection available to the personnel. In addition to the Machinery Directive. such as the Pressure Equipment Directive or the Explosion Protection Directive. It is most important for you to also consider the possible use of the hydraulic product in a potentially explosive atmosphere (see 94/9/EC). please refer to the Product-specific Operating Instructions.1 Noise protection The A-weighted equivalent continuous sound power level of Rexroth hydraulic products can be obtained from the relevant Operating Instructions. and if so. translated into another language or employed or copied for other purposes or by other parties without such consent.4 Copyright This product information may only be reproduced – electronically or mechanically. Please refer to our general terms of supply or your contract for details of the guarantee and manufacturer’s warranty. amended.3 Bosch Rexroth AG Hydraulics Liability. Bosch Rexroth shall not be liable if a deficiency occurs that involves parts having been replaced by the customer with equivalent but not identical parts as specified by the manufacturer.6/32 2. Bosch Rexroth shall only be liable if the scope of delivery was shown to be defective. General product information RE 07008 . guarantee. warranty Bosch Rexroth shall not be liable for damages that result from non-compliance with or disregard of these and other parts of the Operating Instructions. Unauthorised tampering shall render the warranty null and void. in whole or in part – with the express written permission of Bosch Rexroth. transmitted. 2. It may likewise not be distributed. Secure the main switch against being unintentionally switched on again. bypassed or rendered ineffective. transmission. observe the provisions of the safety datasheets issued by the manufacturer of the pressure fluid and the fire precautions specifically applicable to your place of work. The following information can be found in the Operating Instructions: Ø the proper use. Ø Rexroth hydraulic products are designed and constructed for the provision. In the event of an emergency.1 General product information Hydraulics 7/32 Important basic safety instructions IMPORTANT What to do in an emergency The hydraulic product shall be operated exclusively with pressure fluids complying with DIN 51524. Ø If the hazard analysis/risk assessment of the overall machine in which the Rexroth hydraulic product is to be installed indicates that a safety category higher than category B in accordance with EN 954-1 is required for the Rexroth hydraulic product. For details on proper use see 4 Technical data and ambient conditions. Notify the relevant specialist personnel immediately. Switch off the hydraulic system. Ø Rexroth hydraulic products shall not be converted or otherwise modified without prior consultation with Bosch Rexroth. control or regulation of energy and signals using the flow of oil. Ø Dependencies and time factors shall not be modified without prior consultation. this is specially mentioned in the Operating Instructions.3. They shall not be relocated. the Rexroth hydraulic product satisfies at least safety category B in accordance with EN 954-1. specific to the hydraulic product Ø where applicable. Safety components such as limit switches. Ø For a diagram of the nameplate and an explanation of the information on it please refer to the Operating Instructions. IMPORTANT Ø The meanings of the safety labelling on the Rexroth product are explained in the Operating Instructions.RE 07008 3 3. Secure the danger area so that no one can enter the danger area unknowingly or uncontrolled. properly installed and in full working order – except when this is impractical during setting up or maintenance work.1 Proper use. fault or other abnormal occurrences: 1. • In the event of disturbances in the power supply and/ or damage to the electrical equipment. valves and other control components shall not be rendered inoperative. 5. 3. the safety category in accordance with EN 954-1 Ø non-permitted and improper use. Tamperproof lead seals installed by the manufacturer shall not be removed or damaged except when this is necessary in the course of maintenance tasks defined in the Operating Instructions. for example brake fluids for brake valves. 3. then a correspondingly higher rated hydraulic product can be supplied and installed only after special agreement with Bosch Rexroth. 3. switch off immediately and secure the main switch against being switched on again without authorisation. • Report and rectify all faults and damage indicated by the system or discovered by other means. Where other pressure fluids are permitted.2 Bosch Rexroth AG Safety labelling on the hydraulic product Rexroth hydraulic products may only be operated if they are in perfect technical condition. Ø The connections. Ø The specified maintenance tasks in the Operating Instructions shall be carried out at the intervals stated in the Operating Instructions. operating conditions and performance data specified in the Operating Instructions must be observed and never changed. 4. 2. Ø The plant operator shall not modify the program code of programmable control systems. The safety devices fitted by Rexroth must be present. which must be documented in the plant operator’s operating manual. requirements before operation Ø WARNING Fighting fires with materials other than those permitted can lead to explosions and/or more rapid spread of the fire! Danger to life from smoke inhalation! 3.3 Proper use . Ø Unless otherwise agreed. In the event of fire. 2 Requirements for hydraulics maintenance personnel In accordance with DIN 31051. Ø Repair personnel must be familiar with the function of the hydraulic system as a whole.4. Inspection personnel shall fulfil the following requirements: Repair personnel shall fulfil the following requirements: Ø The personnel must be hydraulics experts.4 Minimum age Persons under the age of 18 who are currently receiving instruction or training or are working under supervision may not work on Rexroth hydraulic products. Ø working on Rexroth hydraulic products is necessary in order for them to accomplish a training objective Ø their protection is guaranteed by the supervision of an experienced.4 Bosch Rexroth AG Hydraulics General product information RE 07008 Uncontrolled access by persons unfamiliar with the system to the immediate operating zone of Rexroth hydraulic products is prohibited (even if the product in question has been shut down). qualified electrician. drugs or other medication which affect one’s ability to react. operated or maintained by persons under the influence of alcohol.4. servicing and repair. Ø Repair personnel must be able to read hydraulic circuit diagrams. Ø Repair personnel must possess knowledge of the function and construction of hydraulic elements. competent person Ø they are allowed to use only tools.1 Qualifications of specialist personnel A specialist person is someone who. Ø They have been instructed in the relevant activity. or by instructed persons under the guidance and supervision of a qualified electrician. Ø Specialist knowledge of hydraulics is not required to carry out servicing work. can Ø safely carry out the tasks allocated to him and correctly assess the scope and implications of his work Ø recognise possible dangers Ø undertake the necessary measures to eliminate possible accidents. in accordance with the rules applicable to electrotechnical products. using his specialist training. 3. who have been instructed and meet the definition given above. maintenance comprises the individual activities of inspection.3 Requirements for electrical maintenance personnel All work on electrical equipment shall only be carried out by an authorised. Requirements for personnel. All personnel involved in maintenance shall be familiar with and observe all parts of the Operating Instructions and this product information. from subsystems to their interaction with the function of the entire machine. for example) shall fulfil the following requirements: Ø They have been instructed in the relevant activity. Servicing personnel (who carry out filter and oil changes. This does not apply to young persons of 16 or over if Ø Specialist knowledge of hydraulics is not required for purely inspection activities but the personnel must be aware of the particular dangers associated with hydraulic products.8/32 Ø Ø 3.4. . knowledge and experience as well as familiarity with the relevant conditions. work implements and protective gear that preclude the risk of injury. interpret individual functions from their symbols and understand function diagrams. 3. 3. Rexroth hydraulic products must never be assembled.4. duty of care 3. . Therefore the maintenance tasks specified in the Operating Instructions shall be carried out at regular intervals and the utmost cleanliness is required during work on the hydraulic product. additional dangers may arise if the hydraulic product is installed in another machine or installed with other machines in a system.5. CAUTION When changing the pressure fluid. The cleanliness class of a pressure fluid is specified in accordance with ISO 4406.5 Training Hydraulics Observation and use of the Operating Instructions and legal requirements Ø Proper operation of the Rexroth hydraulic product Ø Observation of the instructions of safety officers and the plant operator’s operating manual Ø What to do in an emergency. In spite of the high intrinsic safety of Rexroth hydraulic products. Flush out lines and hoses before installation.1 Dangers from pressure fluid The plant operator using Bosch Rexroth hydraulic products shall train his personnel regularly in the following subjects: Ø Bosch Rexroth AG CAUTION Handling pressure fluid without protection is hazardous to health.RE 07008 General product information 3. contact a doctor immediately! An overview of the training can be found on the Internet at http://www. the risk of personal injury or damage to the environment cannot be excluded. increased wear and shorter service life of the hydraulic product. Ø The use of dirty (unfiltered) pressure fluid when the pressure fluid is changed. This can have negative effects on the safety and reliability of the hydraulic product.2 Malfunctions due to contamination of pressure fluid 3. Information on these additional dangers can be found in the overall operating manual of the supplier of the overall system in which the hydraulic product is installed. 3.boschrexroth.5 General ancillary dangers and protective measures when operating hydraulic products Contamination of the pressure fluid can be caused by: Ø Wear during operation of the machine/system (metallic and non-metallic abrasion) Ø Leaks of the hydraulic product Ø Contaminants introduced during servicing/repair In the interests of your safety. This shall apply in particular to mechanical movements generated by the hydraulic product. Contaminants lead to malfunctions.de/didactic. Detailed information can be obtained from the relevant datasheet or the Operating Instructions. even when the equipment is properly used. IMPORTANT Bosch Rexroth can provide you with training support in specialist areas. DANGER New. Please observe the manufacturer’s safety instructions and the safety datasheets for the pressure fluid that you are using. always use factory-fresh pressure fluid and filter it before filling to remove any contaminants in the pressure fluid that it often contains from the packaging container (drum). especially those in the Operating Instructions. all safety instructions shall be carefully observed.4.5. If this occurs. DANGER Serious damage to health or death may result if pressure fluid enters the blood stream or is swallowed. 9/32 3. • Always use electrically insulated tools. Ø Dispose of back-up batteries as special waste. electronics. Wear safety footwear.5 Disposal Ø Take metal. operating fluids and other materials: When working on electrical systems: • De-energise the hydraulic system before beginning any maintenance work.4 Product-specific ancillary dangers All product-specific ancillary dangers and precautions can be found in the relevant Operating Instructions. cable and plastic ducts to a recycling materials collection centre.5. rechargeable batteries) Ø Main switch Ø Power supply cables Ø Points identified with an electric shock warning sign. DANGER Even after disconnection of the electrical supply (main switch OFF) the following supply systems/danger areas can still give rise to life-threatening voltages: Ø Electrics.5. The following table can be used to convert this to an equivalent ISO 4406 cleanliness class: Comparison table for cleanliness classes Earlier class to Current class to NAS 1638 ISO 4406 (c) Class 7 Class 18/16/13 Class 9 Class 20/18/15 3. • Cover neighbouring live parts. the cleanliness class is sometimes specified in accordance with NAS 1638. Ø Cleaning agents. • Cordon off the working area with red-white safety chain and warning signs.5. remove the key and keep it in a safe place until the work is completed. • Lock the main switch. hydraulics (e.g.3 Electrical dangers General product information RE 07008 3. • Clear your workplace to prevent contact with live parts as a result of tripping or slipping. • Attach a warning sign to the main switch. • Earth and short-circuit the point where you are working. .10/32 Bosch Rexroth AG Hydraulics In older datasheets. • Check that there is no voltage using a two-pole voltage detector. 3. accumulators. Ø Dispose of electronic components as electronic waste. CAUTION Please observe the disposal regulations specified in the appropriate Safety Datasheets. • Disconnect plugs at sensors and valves – even those with low voltages – after the system has been de-energised. IMPORTANT Rexroth hydraulic components are tested with test oil MZ45 manufactured by ESSO (class ISO VG 46 at 40 °C). Operating temperature range 0 °C…+80 °C (in tank < 72 °C). IMPORTANT Bosch Rexroth recommends a maximum operating temperature of 55 °C. Observe the requirements of Directive 94/9/EC of the European Parliament and Council dated 23 March 1994 on the approximation of laws of the member states concerning equipment and protective systems intended for use in potentially explosive atmospheres (ATEX Product Directive) and/or the corresponding national legislation by means of which the Directive was implemented in law in the EU member states. (Viscosity η = approx. The following types of pressure fluids shall be used.1 Use in potentially explosive atmospheres DANGER Rexroth hydraulic products shall be used in potentially explosive atmospheres only if they are designed for this purpose and this is expressly stated in the Operating Instructions.2 Bosch Rexroth AG 11/32 Ambient conditions 4. 46 mm2/s). permissible contamination class of the pressure fluid in accordance with ISO 4406: see 3. Ø Viscosity ranges: see RE 07075 and RE 90220 Ø Max. dividing areas endangered by potentially explosive atmospheres into zones and specifying suitable work equipment and procedures for these areas.2 Malfunctions due to contamination of pressure fluid. 4. for example.5.RE 07008 4 General product information Technical data and ambient conditions IMPORTANT The product-specific technical data. The directive contains requirements for the use of equipment and protective systems in potentially explosive atmospheres. IMPORTANT Directive 1999/92/EC of the European Parliament and Council dated 16 December 1999 concerning the minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres governs protection from danger from potentially explosive atmospheres. This includes the following information: Ø Minimum flow rate for adequate cooling Ø Permissible maximum temperature of the coolant Ø Performance data Ø Type of control and regulation functions Ø Permissible pressures. Observe the requirements contained in the regulations for operating equipment requiring supervision and the obligation to produce explosion protection documentation.2.1 Information about pressure fluids Unless otherwise indicated in the Operating Instructions. Hydraulics 4. because the rate of ageing of the pressure fluid increases and the service life of the seals and hoses is reduced at higher temperatures. flow rates Ø Connections. . This involves. the following specification applies to the pressure fluid to be used: Ø Ø Mineral-oil-based pressure fluid complying with the requirements of DIN 51524. Any deviations from this can be found in the Operating Instructions. The maximum permissible cleanliness class can be found in the Operating Instructions. operating limits and ambient conditions for the operation of your Rexroth hydraulic product can be found in the Operating Instructions. IMPORTANT For systems with oil-air heat exchangers: Observe the information given in the circuit diagram in the Operating Instructions. the permissible ambient temperature Ø for control units: 0 °C…+50 °C Ø for drive units with electric motors without heat exchangers. surface-cooled by free air circulation: 0 °C…+30 °C Ø for drive units with heat exchangers: < +40 °C. except where they have been specially approved and appropriately labelled to this effect. Ø Ambient temperature +5 °C…+40 °C assuming that the average air temperature over a 24 hour period does not exceed +35 °C.2. the permissible ambient conditions apply to installed and protected electrical connections of class IP 55. non-condensing. Unless otherwise specified.12/32 Bosch Rexroth AG Hydraulics 4. General product information RE 07008 . Rexroth hydraulic products are designed for use in temperate climate zones and in covered areas (not in the open air) at relative air humidities of < 70 % and at room temperatures of 22 °C. DANGER Rexroth hydraulic products shall not be used in aeronautical equipment. Ø Altitude: up to 1000 m above national datum.2 Climatic operating conditions Unless otherwise indicated in the Operating Instructions. In relation to the electronic equipment. Ø Relative air humidity: 23…95 %. pumps and hydraulic motors. The relationship between medium temperature and viscosity for hydraulic oil (example) Medium temperature 3 °C 8 °C 25 °C 60 °C 77 °C Viscosity 800 mm2/s 500 mm2/s 100 mm2/s 20 mm2/s 12 mm2/s Too high a viscosity leads to the formation of air and vapour bubbles as a result of low pressure (cavitation). It may only be used if the relevant safety datasheet from the manufacturer is present and all the measures stipulated therein have been implemented.3 Viscosity DANGER Mineral-oil-based pressure fluid is hazardous to water and flammable.RE 07008 5 5. leading in turn to a further reduction in viscosity. 5. The pressure fluid then loses its ability to lubricate.1 General product information What you need to know about pressure fluids Hydraulics Bosch Rexroth AG 13/32 IMPORTANT Observe the following rules of thumb: At pressure fluid temperatures >70 °C. inspection and maintenance are of vital importance for: Ø proper functioning Ø operating safety Ø service life Ø and the cost effectiveness of the hydraulic product.e. the equivalent of [mm2/s]. The viscosity grades (VG = viscosity grade) in accordance with ISO 3448 relate to the viscosity at 40 °C. Viscosity range always plays a priority role in the selection of a pressure fluid. not all the requirements can always be covered with the available ranges of the viscosity grades. Valves. Acids and resinous residues form. 5.2. For certain ambient and operating temperatures.2 Functions and effectiveness Due to the many tasks of pressure fluid. in particular. The following factors accelerate the ageing process: Ø high temperatures Ø oxygen in the pressure fluid Ø air humidity Ø water Ø metallic catalysers Ø operating pressure Ø contaminants. How to handle pressure fluids safely 5. The viscosity grade is appended to the type designation or the commercial name of the pressure fluid. i. stickiness. Many manufacturers still provide their information in centiStoke [cSt]. the rate of ageing doubles for each 10 °C. The tasks of pressure fluid: Ø to transmit hydraulic energy from the pump to the hydraulic cylinder/motor Ø to lubricate parts moving against one another Ø corrosion protection Ø to remove contaminants Ø to remove locally accumulated heat. Example: A pressure fluid with a viscosity grade of ISO VG 46 has a viscosity of 46 mm2/s at 40 °C. In order to comply with all the requirements.1 Viscosity grades The most important characteristic of a pressure fluid is its viscosity. Increased leakage losses cause the pressure fluid to heat up more. high viscosity pressure fluids with viscosity index improvers or a pressure fluid cooler/heater may be used. which may cause valve spools to stick.1 Reduced function due to ageing The effectiveness of pressure fluid diminishes as it ages (undergoes chemical changes). require exact compliance with the defined viscosity ranges. .3. 5. Too low a viscosity leads to increased leakage losses. Viscosity is measured in the SI unit [mm2/s]. its selection. General product information RE 07008 . Dispose of leakage fluid that is not fed back into the tank properly. depending on the component. make sure that you use pressure fluid of the same sort and type and from the same manufacturer. New pressure fluid must always be filtered in accordance with the required cleanliness class. in compliance with the applicable environmental protection regulations. 5. then the system. including the tank must be cleaned and flushed before refilling. as it does not normally meet the required cleanliness class in the as-supplied state. Leakage fluid can be lead away internally or externally.4 Bosch Rexroth AG Hydraulics Leakage fluid Clearances and play mean that some leakage fluid escapes from all hydraulic products.5 Topping up/refilling CAUTION When topping up/refilling your hydraulic system. It can be fed back into the tank or must be disposed of. CAUTION Make sure that the leakage fluid is fed back into the tank in a proper manner.14/32 5. If the fluid is heavily contaminated or prematurely aged. Drive A component that converts the energy of the hydraulic fluid into mechanical energy (e. a valve.g. 6. The following diagram shows a schematic representation of the elements of a complete hydraulic system. the interaction of which is particularly important with regard to the fulfilment of technical safety functions. motor.2 Schematic In a system operated with hydraulic oil. The manufacturer of the overall machine or system defines and bears responsibility for the safety category to EN 954-1 to be fulfilled. first of all mechanical energy is converted into hydraulic energy. control and distribution of energy and signals using a pressurised fluid medium. motor) that consists of one or more parts and which is a functional constituent of a hydraulic system. IMPORTANT A more detailed description of the safety concept and the specific safety components installed can be found in the Operating Instructions and the Operating Instructions of the supplier of the overall system in which the hydraulic product is installed.RE 07008 6 6. cylinder). 15/32 2 1 1 Tank 2 Filter 3 Pump 4 Pressure limiting valve 5 Directional valve 6 Check valve 7 Throttle valve 8 Hydraulic cylinder 9 Hydraulic motor 6. 4 3 Component A single unit (e. . Line connections are represented by simple lines. 6 Hydraulic system 5 Arrangement of interconnected components for transferring and controlling hydraulic energy. Applications required to perform safety functions are designed using special hydraulic components that satisfy the requirements of the relevant directives. filter. To demonstrate their operating principle. transported and controlled in this form. Individual hydraulic products form part of an overall safety concept. The hydraulic elements are arranged in accordance with these functions. as can be seen in the example.1 General product information Bosch Rexroth AG Hydraulics Construction and mode of operation of a hydraulic system 9 Definitions of terms 8 Hydraulics (fluid technology) 7 Transmission. to finally be converted once more into mechanical work.g.3 Oil preparation Energy conversion Energy control Energy conversion Safety concept Hydraulic products contain sensors and actuators. cylinder. such as the Pressure Equipment Directive and other standards. standardised symbols (ISO 1219) are used instead of sectional diagrams of the various devices. especially oxidation.2 Storage times in relation to the ambient conditions Delays in bringing into use. 8. which detrimentally affects the functioning of the hydraulic system. IMPORTANT For details see the Operating Instructions. Rexroth hydraulic products are delivered empty of pressure fluid. 8. IMPORTANT If all the openings on the hydraulic products are not sealed so as to be air-tight. Additional corrosion protection measures must be implemented to prevent this. depending on their size and the local conditions. 8 Storage and longer standstills 8. products may contain oil residues left over from the final inspection at our factory.1 Factory-applied corrosion protection Rexroth hydraulic products are tested in accordance with Class III using a hydraulic oil that has additional anti-corrosive properties. it must first be flushed clean. Rust and other metallic and non-metallic particles lead to abrasive wear (erosion). This factory lubrication ensures that valves do not stick during subsequent use of the hydraulic product. the corrosion protection must be checked and further conservation measures applied if necessary. in any event not longer than 24 months. can cause metal surfaces to lose the standard of surface finish required for the hydraulic system to function properly. However. After the specified storage time has expired. The film of oil that remains in the product after the test provides sufficient internal corrosion protection. this will reduce the storage life of the hydraulic product by nine months. . and guarantees compatibility with seals and the pressure fluid to be used.16/32 7 Bosch Rexroth AG Hydraulics Moving hydraulic units/components Hydraulic units or components may be moved by a fork-lift truck or a hoist. CAUTION Always ensure hydraulic products are empty of pressure fluid for transportation. Contact Bosch Rexroth if you are not clear about the consequences of long standstills on the state of the hydraulic product.1. long shipping and storage times or long periods of non-use can lead to rust formation in Rexroth hydraulic products.subsequent bringing into use after storage Corrosion.1. CAUTION If a hydraulic system is to be brought into use again following a long standstill.1 Hydraulic systems . General product information RE 07008 IMPORTANT The factory-applied corrosion protection is adequate provided that Ø no condensation or leakage water can enter the system Ø long standstills are avoided. hoses and hose lines must not come into contact in particular with materials or vapours that could damage them (e. laser printers) or electrical spark-forming devices in the vicinity of hoses and hose lines. hoses and hose lines are stored in cool. hoses/hose lines shall not be used once these permissible storage times are reached or exceeded. alkalis. Ø Avoid direct sunlight and UV radiation and shield from nearby sources of heat. please observe the requirements of DIN 20066.g. The ideal storage conditions for seals are temperatures from +10 °C to +20 °C and a relative humidity of between 65 % and 75 %. Ø Do not use ozone-forming light sources or equipment (e. Permissible storage times could be considerably reduced if the permissible storage conditions are not maintained. If you are not clear about the storage times and/or storage conditions then you should not use the product. mercury-vapour lamps. Ideal storage conditions for hoses and hose lines are temperatures from +15 °C to +25 °C and a relative humidity of below 65 %. seals. take care not to bend them to less than the smallest bending radius specified by the manufacturer. Ø Darkened storage locations are preferred. the following conditions shall be observed: Ø Seals. hoses and hose lines CAUTION Seals: Observe the requirements of ISO 2230 and/or DIN 7716 and the specific manufacturer’s data on seals. Maximum storage times Ø NBR seals: 4 years Ø FKM seals: 10 years Ø Hoses: 4 years Ø Hose lines: 2 years For reasons of safety. If the hoses and hose lines are coiled. Ø Store hoses and hose lines in the original packaging if possible. copiers. Prevent the entry of air.RE 07008 8. acids. dry and dust-free conditions. In addition. fluorescent lamps.2 General product information Seals. Ø Store seals. Ø Do not store elastomers below –10 °C. hoses and hose lines lying down and free from tension. solvents). The hoses and hose lines can be enclosed in plastic foil to ensure low-dust storage conditions.g. ZH 1/74 Safety rules for hydraulic hose lines and the specific manufacturer’s data on hoses and hose lines. Hydraulics Bosch Rexroth AG 17/32 . Ø Seals. Hoses and hose lines: In the Federal Republic of Germany. Safety advice for assembly and bringing into first use DANGER Hydraulic products are generally intended for installation in machines/systems or devices. The functional or failure behaviour of identical hydraulic products may vary due to conditions specific to the machine or system in which the hydraulic product is installed (mass.18/32 9 Bosch Rexroth AG Hydraulics Assembly and bringing into first use IMPORTANT General product information RE 07008 Bringing into (first) use shall only be done by an instructed. and have clarified and dealt with any possible dangers. 3. consult the people responsible for the overall system/functional machine.). • Ensure that the cylinder piston rod can move out without danger. 9. Specialist hydraulics knowledge means. speed. authorised hydraulics expert who has the required specialist knowledge. check whether bringing the hydraulic system into use could lead to uncontrolled. take into account the hazard analysis/risk assessment for the system or machine. 7. Check that the Operating Instructions for the Rexroth hydraulic product are present and complete. Ø • Observe the Operating Instructions and this product information. Never use hemp and putty as sealants. • Assemble the hydraulic components. seemingly identical hydraulic products may demonstrate different functional behaviours as a result of the function of the machine in which they are installed. 5. a hydraulic drive must not be brought into use until it has been determined that the machine in which it is installed conforms to EU standards. If in doubt. If important documents are missing.e. Check the construction of the hydraulic product against the circuit diagrams. • Use a hoist or other lifting device to additionally secure lifted loads.2 All information specific to assembly and bringing into first use can be found in the Operating Instructions. etc. draw this to the attention of the people responsible. lists of equipment and assembly drawings. Where appropriate. Information on other pressure fluids can be found in the Operating Instructions or are available on request. In particular. Take the precautions appropriate to the anticipated dangers. The function of the hydraulic product must therefore always be seen in relation to the function of this machine – i. he must fully comprehend the range of functions of the integrated safety components as part of the overall safety concept. 9. Depending on the condition of the system or machine. electrical triggering at setpoint values. so that they are mounted strain-free on even surfaces. Do not bring hydraulic drives into use until you have familiarised yourself completely. Make sure that cleaning agent does not get into the hydraulic system.g. e. If there are any differences. Contact us if the Operating Instructions are not there or are incomplete. Check the scope of delivery for transport damage. Assemble the hydraulic product. Ensure that the interfaces of the system/machine and the installation conditions provide for safe operation of the hydraulic product. Use suitable liquid cleaning agents to remove lubricants and other stronger contaminants. among other things. Filling the pressure fluid tank must always take place through a suitable filter unit. dangerous movements. they can be requested from Bosch Rexroth. cleaning with fibre-free cloths may be sufficient. • Tighten the fastening bolts evenly using the specified tightening torque. Based on the Operating Instructions for the system or machine in which the hydraulic product is installed. Only documents issued by the bodies authorised to do so shall be used. 1. firstly with the function of the hydraulic product and hydraulic equipment and secondly with the hydraulically powered machine functions. Pay attention to cleanliness: 2. 6. Ø Do not use cleaning wool or cloths containing fibres for cleaning. Only the permissible pressure fluids given in the Operating Instructions are to be used. that the person can read and fully understand hydraulics drawings. Experience has shown that even new pressure fluid can often have more than the maximum permissible level of contamination. see also Section 11 Trouble-shooting. . For this reason.1 Before bringing into first use 4. as several valves at once cannot be switched as required in the correct sequence. filters. If they cannot be switched manually – or can but with difficulty – you must provide a remote control (e. Pickle and flush welded pipes. 5. pressure and flow control valves. braking valve. • Remove any gummed oil which may have formed due to incorrect storage. scale. 9. IMPORTANT Starting up the hydraulics solely by means of emergency manual operation is not recommended. Ø Pump circuit (generation of pressurised oil flow). e. then finally optimise all settings. More information about the functioning of components. 7. 13. check whether the electric motors and valve solenoids can be switched manually using the electrical controls of the system/machine. CAUTION Remove all residues of water and cleaning agents before performing further work. • Completely remove any oil residues left over from the factory test. prohibitive or informative signs and check whether the meaning of these signs are explained in the Operating Instructions. 8. Clean the interior of the hydraulic components to get rid of contaminants: • Clean the filler plug of the pressure fluid tank. 3. etc. so that no dirt can get into the hydraulic system during bringing into (first) use. test boxes for Rexroth proportional valves) for the internal function test of the hydraulic system.3 Bosch Rexroth AG 19/32 Bringing into first use. monitoring devices. check valves Ø Hydraulic consumers (cylinders. is available in the Technical Datasheet. Follow this sequence for bringing into (first) use Ø Pump circuit Ø Parts of control system: e. chips etc. Ø Control system for at least one hydraulic consumer (cylinder. . open centre. 11.g. Observe the installation instructions from the manufacturer of the connection components. 10. 1.g.RE 07008 8. directional control valves. Draw up a sequential program for bringing into (first) use and store it with the technical documentation as an appendix to the Operating Instructions. pressure reduction etc. motor). motors) with specially assigned valves. Put up any necessary directional. have all pressure accumulators and safety systems checked by an expert or specialist in accordance with national regulations.g. IMPORTANT 14. fill and bleed. 4. oil tank. General product information As part of bringing into (first) use. by rinsing parts or similar cleaning method. a pump regulator. • Remove dust and chips using an industrial vacuum cleaner. or how valves are to be set. Clean the hydraulic unit and all other component groups. subsequent bringing into use DANGER Before bringing into (first) use. Ø Cylinder and motor circuits: First move. 6. Hydraulics 9. Check the paint on the tank for integrity. Carry out a special check to make sure that the union nuts and flanges are correctly tightened at the pipe connections and flanges. Connect up all connection lines. 12. Flush the connection lines to remove dirt. Read the functional circuit diagram and seek clarification of any unclear text or diagrams. DANGER Make sure that pipes and hoses are connected at all ports or that the ports are sealed with screw plugs. Divide the functional circuit diagram into separate mini-circuits that can each be started up in succession. pump. Establish into which position valves are to be switched. For this you should consider the following: Hydraulic drives basically consist of the following functional groups 2. e. pressure cut-off and switchover. Clean the lock on the transport and storage container before opening. electric motor.g. 10. If the pressure fluid has a high level of initial contamination (see 4 Technical data and ambient conditions): 16. Ensure that the filter element is clean. Start the drive motors: The fineness of the filter shall correspond to the cleanliness class required by the overall system and if possible be even finer. 11. If applicable: Fill the pressure accumulator to the specified gas precharge pressure and then check the pressure. Ø The drums of pressure fluid must be sealed and clean on the outside. 13. taking into consideration the volume in the connection lines and hydraulic consumers. Use a filter unit to fill the pressure fluid tank. see Operating Instructions. Fill the pump body: Use the leakage oil port to fill pump bodies that have this feature. 9. 12. • Set directional control valves to their basic setting. • With electric motor in jogging mode. • Do not remove the tamperproof lead seals. Observe the maximum fluid level.g. CAUTION Never fill new hydraulic products with used pressure fluid. Before filling the pressure fluid tank. with paint. • If possible.20/32 Bosch Rexroth AG Hydraulics General product information IMPORTANT CAUTION Mark all the checked connections. using a return filter if possible. DANGER Do not change the settings of valves with a safety function. e. Damaged or removed tamperproof lead seals indicate improper use of the hydraulic product. IMPORTANT RE 07008 15. 14. please observe the following requirements: Ø The pressure fluid must conform to the specification in the Operating Instructions. Use oil filler units (filter units) suitable for pressure fluids. signalling elements such as pressure switches. 17. Dimension the connection lines in accordance with the performance data in the Circuit Diagram and the Operating Instructions. If applicable: Open the cocks in the suction line. • Connect coolant water if necessary. Set the pressure and flow control valves. fill the pressure fluid tank via a filling coupling. .2 Before bringing into first use). Check the pressure fluid to ensure that no water has entered it. Make sure that all pipes and hoses and every combination of connection pieces. IMPORTANT 18. allow to start briefly • Combustion engines in idle • Pay attention to the direction of rotation. pump regulator.g. • Set operating-pressure valves and flow control valves to the lowest possible values. Install the electrical system for the drive and control system: • Check the connected loads. • Do not remove the filter strainers from filler necks or the filter element from filters before filling the pressure fluid tank. The filter unit used shall fulfil the requirements for functional safety and service life. Connect the hydraulic consumers. • Check the direction of rotation of the pumps (e. valves with a position switch or valves with preset electronics. see Operating Instructions. • Reduce the setpoint values of proportional valves to minimum values. couplings or connection points with hoses or pipes are checked for their operational safety by someone who has the appropriate knowledge and experience. as indicated by attached arrow markings). limit switches and temperature regulators to the settings and values defined in the sequential program (see 9. Fill the pressure fluid tank up to the upper mark on the inspection window. which should not be sufficient to form one drop. Replace the pressure fluid filter. see Operating Instructions. Valves with in-built electronics (OBE. have a sample of the pressure fluid analysed to ensure that it achieves the required cleanliness class. after bringing the machine into first use. On Board Electronics) have the valve and amplifiers adjusted in line with one another at the factory. Too high an operating temperature indicates that there are faults that need to be analysed and rectified. Bleeding has been accomplished fully and correctly if the pressure fluid in the tank does not foam. Set the valves and sensors and start up the machine: • • Set the switching operations of valves with a switching time adjustment/ramp in accordance with the dynamic conditions. IMPORTANT Information on how to perform the function test and pressure test can be found in the Operating Instructions. Rectify any leakages. unintentional leakage shall be found. Bleed the hydraulics (valve. Prepare a record of the bringing into (first) use or acceptance and have it signed by the plant operator. • Operate the directional valves in jogging mode. • Next. 21. After bringing the machine into first use. Change the pressure fluid if the required cleanliness class is not achieved. 20. To ensure the safety of persons and the system. Depending on the type of valve and amplifier. Amplifiers for valves without OBE are supplied from the factory with a basic setting. This record is an important document and requires to be filed. IMPORTANT Details on bleeding can be found in the Operating Instructions. line. no measurable. • Increase the load slowly. 24. you may have to fine-tune the null point and sensitivity before bringing the valve into use. IMPORTANT Details on fine-tuning can be found in the Operating Instructions. IMPORTANT Apart from moisture. e. Manufacturing tolerances mean that valves and amplifiers have to be adjusted in line with one another. cylinder). perform the following tests using the defined maximum values: • Function test • Pressure test. Check the operating temperature after the machine has been running continuously for several hours. pump. Document and file all set values. If the pressure fluid is not tested in the laboratory after bringing the machine into first use: Change the pressure fluid. • Bleed the hydraulics lines to consumers or measuring points at the highest point. • Operate the hydraulic product at low pressure until it is fully bled. Finely adjust and optimise the setting of proportional valves without on-board electronics (OBE). 22. advance and retract all hydraulic consumers several times. . DANGER 26. top it up with pressure fluid. by relieving couplings from pressure and then retightening.g. motor. Hydraulics Bosch Rexroth AG 21/32 23. if possible. If necessary. 25. Check the pressure fluid level in the pressure fluid tank. if the hydraulic consumers do not make any jerky movements and if no abnormal noises can be heard.RE 07008 General product information 19. Where hydraulics are combined with electrics/electronics. if necessary. electrics. Indiscriminate. Ø If no hydraulic circuit diagram is available: Can a hydraulic circuit diagram be drawn using the structure.22/32 10 Bosch Rexroth AG Hydraulics Operation General product information Ø RE 07008 Is there a machine record book that may document similar malfunctions in the past? IMPORTANT Please refer to the Operating Instructions for all information on how to operate the Rexroth hydraulic product.1 General conditions Ø Have the operating conditions or operating range of the hydraulics been changed? Ø Have modifications (e. retrofitted equipment) or repairs been carried out on the overall system (machine/system. in the worst case. Ø Are there enough measuring points? Ø Has the customer provided useful information about how the malfunction manifests itself and about the functional behaviour of the system/component prior to the malfunction? . in particular. changed set values. trouble-shooting is rendered more difficult and cooperation between electricians and hydraulic specialists is required. proceed systematically and methodically.1 What to do in the event of a fault 11. If applicable. 11 Trouble-shooting 11. • Try to find out whether the hydraulics performed the required function in the overall system prior to the occurrence of the fault. If the responsible personnel are unable to rectify the problem immediately: • Switch off the main switch. result in the original cause of failure being impossible to determine. • Inform the machine manufacturer.g.2. hasty dismantling and readjustments may. • Even if you are under time pressure. • Make sure that you gain an overview of the function of the hydraulics in respect of the overall system in which the hydraulics are installed. 11.2. Ask the machine operators directly. etc. 11. turn off any combustion engines used as drive motors. • Try to determine any modifications to the overall system in which the hydraulics are installed: DANGER In the event of abnormal occurrences or malfunctions. • Secure the main switch against being unintentionally switched on again. signs and labelling of the equipment? • Document any amendments/additional information that should be included in the Operating Instructions.2 The basic approach to trouble-shooting The information in this section is intended to help you create the ideal conditions for carrying out trouble-shooting as efficiently as possible. IMPORTANT A table for product-specific trouble-shooting can be found in the Operating Instructions. Ø Is all the necessary technical documentation to hand? • Document any work undertaken.2 Recommended way of working when trouble-shooting Successful trouble-shooting for a hydraulic product requires precise knowledge about the structure and method of operation of the individual components. stop all work on the Rexroth hydraulic product immediately and inform the responsible personnel. control system) or on the hydraulics? If yes: What were they? Ø Have the set values of the hydraulics been changed? Ø Have the hydraulics recently undergone maintenance? Ø Has the hydraulic product/machine been operated improperly? Ø How does the malfunction manifest itself? • Form a clear picture of the cause of the fault. temperature of hydraulic fluid. general rules for trouble-shooting can only be laid down to a limited degree.3 Trouble-shooting tables IMPORTANT The causes of failure in hydraulic systems can be extremely complex. and note down how you discovered them. noises)? Have there been any identical or similar failures in the past? • Make a note of causes of failures with a low probability. .2. measurements or tests). Please refer to the relevant Operating Instructions for product specific information about trouble-shooting the Rexroth hydraulic product. Therefore. disassembly. replacement intervals of filter elements. • Verify these listed failure causes one after the other (by means of theoretical conclusions. • Document the causes of failure you have discovered.g.RE 07008 General product information 11. • Draw up a list of priorities of the most probable failure causes. Only investigate the failure causes you have noted down if all failure causes with a high probability have been proven to be inapplicable. Hydraulics Bosch Rexroth AG 23/32 11.3 Systematic trouble-shooting procedure Ø Ø Is there an inspection and maintenance book which might provide information about the trend of test parameters (e. • Open with care any segments that have to remain under pressure. . • Ensure that only authorised personnel remain in the work zone.24/32 12 Bosch Rexroth AG Hydraulics Maintenance General product information RE 07008 Before undertaking any manual intervention in the Rexroth hydraulic product: 12. completely and within the stipulated periods and make a record of the work. such as servo cylinders. • Allow pressure lines and sections of the system which have to be opened to cool down before commencing maintenance work. Exercise extreme vigilance when operating the hydraulic product in maintenance mode. • Check safety devices regularly to see that they are working properly. which may in certain circumstances necessitate the temporary removal of certain safety devices. Ø For reasons of safety.2 Safety during maintenance tasks DANGER In the interests of safety. • Depressurise the hydraulic product (relieve any pressure accumulators of pressure). • Inform all personnel before commencing maintenance work. Observe the following: Ø Only new. • Wear safety glasses. attach warning signs to the control cabinet. • Relieve any accumulators of pressure in the proper manner. also continue to remain under pressure because the proportional valves remain in the closed position (all valves are illustrated in their basic position in the hydraulics diagram). Ø Inspection (determining the actual condition) • Lower all loads. If you have to switch off the hydraulic product. gloves and boots. • Perform all maintenance work properly. Ø Repair (restoring the desired condition). Certain segments. Since check valves are located in the pressure lines above the pumps. replacement parts and lubricants in original-equipment quality are approved for use/replacement. 12. • Switch off the pressure supply and secure the hydraulic product against being inadvertently switched on again. Please refer to the Operating Instructions for all the necessary information on depressurisation and on those parts of the Rexroth hydraulic product that are not depressurised automatically.1 Definitions of terms DANGER The term Maintenance as defined in DIN 31051 encompasses all measures to maintain and restore the desired conditions and to determine and assess the actual condition of the technical devices of a system . the hydraulic system may still be under pressure even after it has been disconnected from the actual pressure supply. interchangeable and tested components. These measures are divided into the following categories: • Advance all cylinders to their safe end position. please observe all the following safety instructions carefully and at all times. In particular. secure it against being unintentionally switched on again as follows: • Switch off all drives. actuators and points of access. • Secure the main switch against being unintentionally switched on again. • Inform all persons of ongoing maintenance work by means of the appropriate signs. the installation of used and/or untested components is strictly prohibited and leads to loss of EU Conformity. Never perform any maintenance work on raised units without external support. disconnect the hydraulics from the mains at the main switch. • Mechanically support vertical cylinders so that they cannot drop. main switch. Ø Servicing (maintaining the desired condition) • Switch off all pumps. • Generously cordon off the maintenance zone before commencing work. The above measures include: Ø Adapting maintenance objectives to suit company objectives Ø Determining appropriate maintenance strategies. 3 Inspection and servicing The objective of inspection and servicing is Ø To maintain all system functions along with the initial parameters of the system Ø To ensure continual availability of the system Ø To detect weak points Ø To ensure that the system attains the required service life. We strongly recommend the use of an inspection and servicing book. 12. • Remove all tools and materials needed for maintenance from the hydraulic product. and all inspection and servicing intervals should be defined and documented. Hydraulics Bosch Rexroth AG 25/32 • Document and file details of any work undertaken. Do not use cleaning wool or cloths containing fibres for cleaning. • Document and file details of any amendments/additional information that should be included in the Operating Instructions. An inspection and servicing book is also helpful in that Ø It provides comparison values to aid with early detection of malfunctions Ø It allows warranty claims to be dealt with more easily. • Seal all openings using protective caps.RE 07008 General product information Make sure that all safety devices are properly installed and have undergone a function test before bringing the system (back) into use. CAUTION Ensure cleanliness during all work. . Always consult Bosch Rexroth about any proposed modifications or additions. in which all work specific to that site. • Always rectify any leakage from the hydraulic product immediately. • Bleed the hydraulic product after each item of servicing work. • Clean the external environment of couplings/joints and devices before disassembly. Do not climb on any parts of the system. changed set values. • When performing assembly work above your height. etc. burning or grinding work on the hydraulic unit or its attachments only with the approval of local safety authorities/fire brigade and with suitable protective covering to prevent ingress of contaminants. • Always inform personnel before (re)starting the hydraulic product. • Perform welding. use the steps and platforms provided by the plant operator. IMPORTANT The following general specifications are based on use of the hydraulic product in central Europe and under the usual operating conditions of commercial and industrial plants. • Please observe the requirements for pressure fluids mentioned in Section 9 Assembly and bringing into first use. • Modifications and additions could affect the validity of the EU Conformity Declaration/Manufacturer’s Declaration. on the system itself (e. it depends on how the system is operated. Thirdly. whether with partial load or partially with excess load. that require regular inspection and servicing.1 Inspection procedures and test equipment. whether it is subject to surge loads or steady load.26/32 Bosch Rexroth AG Hydraulics 12. filling points.2 Location of testing and measuring points IMPORTANT Please refer to the Operating Instructions for the installation location of filling level indicators. general unusual local vibrations Checks for • unusual local temperature zones Checks for • changes in running noise of the unit • changes in flow noise • changes in operating noise in the unit and valve control.3 Inspection and servicing plan. solenoids. Type of test Typical test equipment Typical testing activities Pressure measurement Pressure gauge or sensor with suitable measuring range and connection pipe and connection coupling Checking of Visual inspection – • specified pressure • opening pressure • pressure difference before and after the object under test Temperature inspection Acoustic inspection – • all components securely seated • damage • wear • leakage (formation of oil droplets) – presence of all warning and informative signs Checks for • Temperature measuring instrument The graph illustrates the concept of wear/wear margin. Where hydraulic systems are concerned. testing points.g. corrosive circulating air and dust. the number of cycles and the ambient conditions. IMPORTANT General product information RE 07008 12. surface treatment.3. drainage points. 1 4 � �� 2 1 2 6 �� 3 Wear margin Z0 Time t 3 Repair (corrective maintenance) time (ti2 – ti1) 4 Damage threshold (damage time tS) 5 6 ��� ��� Desired condition after corrective maintenance Failure The reduction in the wear margin reflects wear. firstly. strainers.3. filters. 5 �� ���� Checks for • Touch inspection 12. It is determined during inspection and varies depending. . Keep the indicated typical test equipment ready for this type of work. etc. The wear margin is a characteristic feature used to describe the condition of the system for the purpose of maintenance. hydraulic products. The curve represents one possible form of the wear profile during the period of use. general The following are some of the typical inspection and testing procedures that are regularly used in connection with hydraulic systems and components.3. material selection. quality) and secondly on external influences or boundary conditions such as servicing levels. etc. the curve is also influenced by the cleanliness class and degree of fouling of the pressure fluid. 3. select a lower operating pressure. electrohydraulic systems Electrohydraulic systems with proportional valves must be serviced in accordance with hydraulic requirements and strategies. investigations must be carried out to ascertain whether the introduction of suitable technical measures might counter this reduction in the wear margin to a satisfactory extent.5 Inspection and servicing plan: electrics and control system Consequently. Since their elimination may provide economic and safety advantages. if such measures entail an improvement and this increase is established as the new desired condition for future corrective maintenance. this means that a sudden change in the wear margin must also count as wear. The inspection and servicing plan for your particular product can be found in the Operating Instructions.4 Inspection and servicing plan. In this event. 12.3. Pressure and flow control valves. IMPORTANT The appropriate component characteristics relevant to servicing can be found in the Operating Instructions.7 Set values of valves.3. On this basis. as wear always signifies the reduction in the wear margin. limit switches and temperature regulators are given their optimum setting when the system is brought into first use. The set values of safety valves shall not be altered by the user. The product-specific inspection and servicing plan for electrics and control systems can be found in the Operating Instructions. DANGER The set values of valves with position switches shall only be calibrated or readjusted at the factory. IMPORTANT 12. we refer to these parts as weak points. an overall strategy for system servicing must be developed and documented.3. regulators and signalling elements If such conditions arise. IMPORTANT Check regularly whether all values are correctly set with the aid of the hydraulics diagram and the documented values. pump regulators and signalling elements such as pressure sensors. lubricants. This leads to increased power losses and an unacceptable increase in temperature of the pressure fluid. The time and expenditure required for such measures must naturally be kept in reasonable proportion to the expected degree of success. However. 12. which is understood to be the primary initial variable before wear commences. An increase in the wear margin to over 100 % above its baseline may be achieved through corrective maintenance. In this case. weak points require to be rectified immediately. Certain system parts may be subject to a wear margin which diminishes in such a way that the time available for use is insufficient for the requirements of the plant or operation. and that the element of time on its own is not of decisive importance for wear. but is of considerable interest in the assessment and evaluation of such wear. 12. Any readjustment shall be performed by authorised testing bodies only. Too low a pressure difference between the operating pressure and the opening pressure can lead to frequent opening of safety valves. . lubrication points and associated lubrication cycles can be found in the Operating Instructions.RE 07008 General product information Hydraulics Bosch Rexroth AG 27/32 All the factors mentioned above can exert an influence on the curve but this need not necessarily adversely affect the quality of its information.6 Lubrication points. pressure switches. intervals IMPORTANT The details of the specified lubricants. technical control components must also be incorporated in these servicing cycles. the filter must be replaced by the end of the shift at the latest. even if there are no detectable technical defects in the hose line. If the ambient temperature is low or the pressure fluid is cold.28/32 Bosch Rexroth AG Hydraulics General product information 12.e. If the check function never indicates filter replacement and the contamination indicator is functioning correctly.3. Therefore. although the pressure fluid is in fact clean. Press the indicator button (check function): If the indicator button pops out again immediately. the indicator point has a certain reserve capacity. due to the entry of dirt particles.8 Replacement of pressure fluid filters and ventilation filters CAUTION Unfiltered pressure fluid filters lead to increased wear of all the system’s hydraulic products and can cause functional failures with dangerous effects. Therefore. Hoses that have already been used as part of a hose line shall not be reused in a hose line. its high viscosity may cause clogging to be indicated. • Dispose of the filter in accordance with the applicable regulations. If the filter is not replaced after 8 h.3.4 Service and storage lives of hose lines IMPORTANT In terms of the service life of hydraulic hose lines in these Operating Instructions. The first use may have changed the properties of the hose material to such an extent that reuse of the hose represents a very high risk. e. The dirt-retention capacity of the filter is utilized to the full. Clogged ventilation filters result in inadequate cooling and can therefore cause excessive heating up and malfunctions of the hydraulic system. this may have the following causes: Ø Faulty filter Ø A bypass valve may have been installed and is not closing correctly. replacement and storage lives are measured from the date of manufacture of the hose line. IMPORTANT Check the contamination indicator when the pressure fluid is warm (during or immediately after operation). Procedure: 1. hoses and hose lines are therefore limited (see 8. The replacement and storage lives of seals.9 Checking filters with a contamination indicator Filters with contamination indicators continuously measure the degree of fouling. RE 07008 CAUTION In certain circumstances the contamination indicator does not show a required filter replacement. 12. seals. • Clogged filters must always be replaced immediately. Do not clean clogged filters. i.2 Seals. always replace contaminated ventilation filters immediately. hoses and hose lines). dirt may penetrate the system. .g. resulting in contamination of the hydraulic product. • Allow the contents of the replaced oil filter to drip and fully drain. 12. generally sufficient for a work shift of 8 h. Due to the progressive loss in pressure as the filter becomes increasingly contaminated. 2. always replace contaminated oil filters immediately. Even when properly stored and subjected to permissible loads. hoses and hose lines undergo a natural ageing process. Wait until the hydraulic product has reached operating temperature. Exact instructions on how to replace a filter can be found in the Filter manufacturer’s instructions for use. DANGER Hose lines must be replaced in accordance with the provisions of the servicing plan. Repair (corrective maintenance) is the restoring of the desired condition. Set the pressure setting value on the pump pressure control to minimum or zero pressure. see 9. To do this actuate the cylinder in both directions.6 Servicing pressure accumulators DANGER Pressure accumulators are subject to the national legislation on safety requirements for pressure vessels applicable in the place of installation.RE 07008 General product information Hydraulics Bosch Rexroth AG 29/32 12.7 Repair IMPORTANT IMPORTANT Only pressure fluids specified in the Operating Instructions are to be used. • Clean the external environment of couplings/joints and devices before disassembly. see Operating Instructions. 3. • If appropriate. • Document any amendments/additional information that should be included in the Operating Instructions. Fill and bleed the line system of the hydraulic product from the unit to the cylinder. • Test and monitor the gas precharge pressure regularly. observe the special safety instructions in 12 Maintenance and the safety instructions in the Operating Instructions. Check the level of the fluid after the hydraulic product has warmed up to the operating temperature and adjust if necessary.5 Topping up the pressure fluid 12. subsequent bringing into use. Top up the pressure fluid volume to the specified quantity. IMPORTANT Check the contamination indicator when the pressure fluid is warm (during or immediately after operation). • Bleed the hydraulic product after each item of repair work. Observe the Pressure Equipment Directive 97/23/EC. When changing or topping up the pressure fluid. • Seal all openings using protective caps. Drop the system pressure right down by resetting the pump. The hydraulic product is ready for operation. Inspection and servicing • Carry out the tests required by law. 7. Raise the pump pressure to the system pressure. 10 µm). Do not use cleaning wool or cloths containing fibres for cleaning. 5. its high viscosity may cause clogging to be apparently indicated. . 2.3 Bringing into first use. 6. IMPORTANT The gas precharge pressure is measured with a testing and filling device. Carry out a test run. 4. 12. If the ambient temperature is low or the pressure fluid is cold. 1. Details of the procedure can be found in the Operating Instructions. DANGER Ensure cleanliness during all work. follow the procedure for bringing into first use. fill the pressure fluid tank on the hydraulic product as follows: In addition. Fill the pressure fluid tank using a special filling unit with an integral filter (min. that the person can read and fully understand hydraulics drawings. IMPORTANT See the Operating Instructions. Components may only be dismantled for the purpose of repair to the extent described in the Operating Instructions. Improper installation can lead to serious damage to persons and property. .1 General The regulations applicable at the place of installation concerning hydraulic pressure accumulators (hydrostatic accumulators) must be observed before bringing into use and during operation. soldering or mechanical work on accumulator vessels.7. they will be required during recurring inspections by specialists. It must be completely replaced. Documents supplied with accumulators must be preserved with care. RE 07008 WARNING Do not perform any welding. Do not charge hydrostatic accumulators with oxygen or air. The bringing into use of hydrostatic accumulators shall be carried out by trained expert personnel only. he must fully comprehend the range of functions of the integrated safety components. Hydrostatic accumulators are subject to the national implementation of the EU Pressure Equipment Directive 97/23/EC. 13. Never repair a defective safety valve. Before each subsequent bringing into use after repair work. Pressure vessels have to be pressure tested every 10 years and the information recorded in accordance with the Pressure Equipment Directive 97/23/EC or its implementation in national legislation. Welding and soldering carry a risk of explosion! Mechanical tampering may cause the vessel to burst and the operating permit will be withdrawn. The operator of the hydraulic product is required to check by means of a servicing record that the inspection and servicing plan as been complied with. In particular.1 General safety instructions for repair work DANGER Repair work shall only be done by an authorised hydraulics expert who has the required specialist hydraulics knowledge. installation and operation of hydrostatic accumulators is regulated by the national implementation of the EU Pressure Equipment Directive 97/23/EC and additionally in the Federal Republic of Germany by the Technical Regulations for Pressure Vessels (TRB). Faulty parts may only be replaced by new. tested components in original-equipment quality. among other things. Risk of explosion! Depressurise the system before working on hydraulic installations. This legislation requires the following safety equipment: Ø Device to protect against excessive pressure (prototype-tested) Ø Pressure relief device Ø Pressure measuring device Ø Test gauge connection Ø Shut-off device Ø Optional: electromagnetically operated pressure relief device Ø Safety device to protect against overheating.2 Safety devices relating to hydraulic pressure accumulators The equipping. the hydraulic product shall be accepted by a hydraulics expert. The plant operator bears sole responsibility for compliance with the existing regulations. interchangeable.30/32 Bosch Rexroth AG Hydraulics General product information 12. Specialist hydraulics knowledge means. Any deviations from this can be found in the Operating Instructions. 13 General information about hydraulic pressure accumulators 13. These risks shall be determined by the machine manufacturer by means of a hazard analysis and if necessary provision made for the appropriate safety devices. Hydraulic systems are subject to legislation including the Pressure Equipment Directive and other relevant EU directives that have been implemented in national legislation. fire and/or other dangerous operating conditions. This information shall be included in the hazard analysis/risk assessment of the overall machine carried out by its supplier and in the Operating Instructions of the overall machine. the information contained in the Operating Instructions made available for each hydraulic system by Bosch Rexroth also applies to hydraulic systems. then it must be ensured that the hydraulic system has been designed and is suitable for this use. satisfy yourself that Ø the hydraulic system is suitable for its application in the machine Ø the ambient conditions in the machine are suitable and/or permissible for the use of the hydraulic system Ø other installed items on or in the machine cannot disturb or endanger the functioning or the safe operation of the hydraulic system.RE 07008 14 General product information Hydraulic systems Hydraulic systems are generally intended for installation in machines or systems. This also applies to the specification of the interfaces between the hydraulic system and the overall machine. In addition to the basic information about the installed components. If the overall machine is to be used in a potentially explosive atmosphere. Hydraulics Bosch Rexroth AG 31/32 14. By installing the hydraulic system in a machine or system. Exact information can be found in the EU Conformity Declaration or Manufacturer’s Declaration that is supplied with the hydraulic system or the hydraulic product. this can lead to the generation of life-threatening smoke. . In particular the effect of hydraulic and electrical control of hydraulic drives that create mechanical movement are to be considered. the interaction of the hydraulic system with the overall machine may give rise to changes in the potential dangers.1 Effects of leaks in the hydraulic system on the machine If pressure fluid escapes from the hydraulic system and comes into contact with hot surfaces on the machine. WARNING Before installing a hydraulic system in a machine or modifying an existing hydraulic system in a machine. rights of reproduction and issue.de © All rights reserved.boschrexroth. The data specified above only serve to describe the product.boschrexroth. including applications for intellectual property rights. + 49 (0) 93 52 / 18-0 Fax + 49 (0) 93 52 / 18-23 58 documentation@boschrexroth. The given information does not release the user from the obligation of own judgement and verification. Bosch Rexroth AG.32/32 Bosch Rexroth AG DE Bestellinformation für deutsche Produktinformation: RD 07008 EN Ordering Information for Product Information in English: RE 07008 FR Information de commande pour la notice française Informations générales sur les produits : RF 07008 IT Informazioni d’ordine per le informazioni tedesche sul prodotto: RI 07008 ES Información para el pedido de la información del producto en español: RS 07008 FI Tilaustiedot . We reserve all power of disposal.de www. .com/bri-products → Datenblatt-Suche/Datasheet search → Suche nach Datenblatt/Search by datasheet 07008 Bosch Rexroth AG Hydraulics Zum Eisengiesser 1 97816 Lohr am Main. dansk produktinformation: RDK 07008 EL Πληρφρίε παραγγελία για τι γερµανικέ πληρφρίε πρϊντ: RGR 07008 Hydraulics General product information RE 07008 http://www.suomenkieliset tuotetiedot: RSF 07008 NL Bestelinformatie voor Nederlandse productinformatie: RNL 07008 SV Beställningsnummer för svensk produktinformation: RSK 07008 PT Informação dos dados de encomenda para informação de produto alemã: RP 07008 DA Bestillingsinformationer vedr. Germany Tel. It must be remembered that our products are subject to a natural process of wear and aging. No statements concerning a certain condition or suitability for a certain application can be derived from our information. are the exclusive property of Bosch Rexroth AG.com © This document. Germany Phone +49 9352 18-1041 Fax +49 9352 18-1040 trainingsystems.de www.boschrexroth. Made in Germany Document number: RE 00845/04.brs@boschrexroth. Main.Bosch Rexroth AG Training Systems and Teachware Maria-Theresien-Straße 23 97816 Lohr a.07 Material number: R961003790 . as well as the data. specifications and other information set forth in it. It may not be reproduced or given to third parties wihout its consent.