CHAPTER 1 INTRODUCTION1 INTRODUCTION Diesel Shed Itarsi came into existence on1964. Initially, the shed was designed to home 40 WDM2 locos. Later, it was expanded to home 100 WDM2 locos in the year 1977-78. Further the total holding of shed was increased to 150 locos in the year 1993-94. Present loco holding of Diesel Shed, Itarsi is 177 having different types of locos i.e. WDM2, WDM3A & WDG3A. Diesel Shed, Itarsi is presently the biggest shed on the Western Railway and the 25Rd largest on Indian Railways. The total kilometers earning is approximately 22 lakhkilometers per month and the shed is running a mail link of 96 locos consisting of various prestigious Mail/Express trains. Diesel Shed, Itarsi is also having a Diesel Training School and Hostel attached t o i t . T h e Training School consists of 5 classrooms and various working models o f mechanical and electrical sub assemblies of WDM2 locos. The staying capacity in the hostel is 72 and is having 38 double-bedded rooms. This training School is being mainly utilized for training of running staff for Diesel conversion and refresher courses of FZR & UMB division. In addition to this, this is also being utilized for imparting training to the maintenance staff of the shed. It is also equipped with the recreation facilities &gymnasium with high-tech exercise machines, indoor games etc. Presently, Diesel Shed, Itarsi is ISO0-14001 Certified Shed, which is headed by under the dynamic control of Sr.L.LBhavsar. Mech.Engineer (Diesel), under whom the officers ME-I, DME-II, ADME/H, ADME/R/Mech., ADME/R/Elect, ACMT & SMM/Stores are working. 2 CHAPTER 2 ABOUT THE INDUSTRY 3 About The Industry 1. Brief History of Diesel Loco Shed, Itarsi Diesel Loco Shed Itarsi was established in 1964 with beginning of loco holding 40 nos. It is now rated as one of the premier shed of Indian Railways. The Diesel Loco Shed is now homing WDM‐2, WDM‐3A, WDM‐3D and WDS‐6 class of Diesel Locomotives .The existing holding of the Shed is 171 locos, with a mail link of 97 Locos and goods outage target of 35 Locos. Now shed is ready to take the challenge of homing WDP‐4 (4000&4500HP Locos) GM locos. A full‐fledged Chemical & Metallurgical Laboratory has been established in this shed. Two Effluent Treatment Plant & Incinerator are also available. A Diesel Technical Training Centre for training the supervisors, artisans and operating/running staff is also functional in the Shed. 2. First Loco Homed in Shed : Loco No. 18043 WDM2 3. Details of Heritage Loco : NIL 4. ISO Certification. First Certification ISO 9001–2000 Certified From ICS Mumbai ISO 9001‐2008 ‐ 13.07.2009 Certified from IQCS “Institute of Quality Certifications Services (India)” ISO 14001–2004 – 19.05.2007 Certified from JAS‐ANZ OHSAS 18001–2007 ‐ 2 September 2008 Certified From Certification International (UK) Ltd. nd 5. Type Wise Loco Holding: TYPE OF LOCO WDM 2 TOTAL 52 57 32 18 171 WDM WDM WDS 6 3A 3D TOTAL 4 6. Maximum Holding (Year Number of Locos) : 177 Locos in 2009‐10 7. Present Loco Link : At present Diesel Loco Shed Itarsi is running 97 prestigious mail/Express trains which inter alia includes8. Homing Capacity : 140 9. Augmentation Plans : In order to improve the overall aesthetic and infrastructural facilities lot of works and M&P’s have been planned. The details of which are as under: a). M&P’s : Brazing Machine . Loco cleaning syste . Thermal Imaging Equipment . Boring Machine Speed Recorder Calibrator . Battery Charger Cum Discharger. b).WORKS Augmentation and Improvement of facilities at Diesel Loco Shed Itarsi (Pink Book of 2010‐11 item no. 400) Construction of safe Scrap Yard Up gradation of Governor, FIP & Injector Room at Diesel Loco Shed Provision of Centralized Air Cooling System Modernization of Pneumatic Facility Electronic Lorry Weigh Bridge Integrated Oil Analyzer Spectrometer Re‐Railing Equipment Radial Drilling Computerized load box with building & platform 5 10. Other History : In addition to homing 171 locos, Diesel Shed Itarsi also Maintains and undertakes the complete activities of 140 T Diesel Hydraulic Break Down Crane with ‘A’ class accident relief train. II Vital Statistics: 01. Sanctioned Strength = 1294 02. Man on Roll Strength = 1160 03. No. of Officers = 07 04. No. of Supervisors = 100 05. Total Area = 150000 M² 06. Covered Area = 18632 M² 07. % age of staff housed in Railway quarters = 59% 08. Power Consumption = 1440000 KWH 09. Water Consumption = 226800 Kilo Liter/Year 10. Educational Profile of Staff Up to 8th 14% 8th 13% 10th 23% 10th to 12th ITI,Diploma & Degree 44% 30% Graduate 06% 6 LOCO SHED ENTRANCE Fig1.Entrance of Diesel Shed 7 MAINTENANCE SHED Fig.2Maintence shed 8 COLOR SCHEME OF LOCOS Fig 3.Color scheme of loco 9 CHAPTER3 ORGANISATION STRUCTURE 10 ORGANISATION STRUCTURE Fig 4. Organization Chart of Diesel Shed 11 Fig 5.Organisation chart Railway 12 CHAPTER 4 PLANT LAYOUT 13 PLANT LAYOUT Wheel Cutting Block Minor Assembly Section Management Office Paint Shop Section 14 CHAPTER 5 VARIOUS SECTIONS IN THE SHED 15 Various Sections In Diesel Shed: Turbo Section Expressor Section Compressor Section Power Assembly Section Cylinder Head Section Machine Shop Cross Head Section Water Pump & Lube Oil Section Radiator Section Traction M/C Governor Section Gauge & Valve Section Air Brake Section Electrical Complaint Room Auxiliary M/C Section Electrical Test Room Magnaflux Section Bogie Section Valve Grinding Section Contactor & Relay Room Zyglo Testing Room Fip Section Tsc Balancing Section Draftsman Room Battery Section Metallurgical Lab. Spectro Section Scrap Yard 16 Various Sections In Diesel Shed To maintain various parts of locomotives, Diesel Shed, Ludhiana has different sections for electrical and mechanical repairs & maintenance. Brief details are as under:5.1 Turbo Supercharger Section:Turbo Supercharge is a machine, which uses exhaust of the diesel engine to compress the intake air to improve the engine efficiency to about 1.5 times. At present, 4types of TSCs are being overhauled in this section. ( i ) A L C O ( i i ) A B B T u r b o T u r b o S u p e r c h a r g e r S u p e r c h a r g e r (iii)Napier Turbo Supercharger (iv)Hispano Suiza Turbo Supercharger All these TSCs are fully dismantled and overhauled in this section. The strength of staff of this section is 7. 5.2 Fip & Injector Section:This section is responsible for maintaining the fuel injection pump and the injector of diesel locomotives. The fuel injection pump is responsible for maintaining desired pressure to inject the fuel, whereas the injector has the duty to spray the fuel in the cylinder after atomization. Two types of FIPs are being used at present. ( ( i i i ) ) 1 1 5 7 m m m m F I P F I P All these subassemblies are being dismantled, overhauled and tested in this section. 5.3 Expresser & Compressor Section:The expresser is used to maintain air pressure and vacuum pressure for breaking system in the locomotive. This section is responsible for maintaining this subassembly.Complete expresser or compressor is dismantled and overhauled in this section as per Work Instructions issued to the section. The staff strength of the section is about 30 17 5.4 Power Assembly Section The piston and connecting rod assembly is called as power assembly. 16 power assemblies are being used in one locomotive. Two types of pistons are being used in the locomotive. Steel cap pistons are being used in fuel efficient locomotives, w h e r e a s aluminium pistons are being used in convent ional locomotives. The shed has switched o v e r t o b a r r e l s h a p e p i s t o n r i n g s t o p r o v i d e b e t t e r f u e l e f f i c i e n c y. T h e p i s t ons andconnecting rods are dismantled, cleaned, zyglo tested and again a r e m a d e r e a d y f o r service in this section. The staff strength of section is about 10 5.5. Cylinder Head Section:This section is responsible for maintenance and overhauling of cylinder heads of diesel locomotives. 16 Nos. cylinder heads are there in one locomotive. Each cylinder head has four valves, two exhaust and two inlet valves. In fuel-efficient locomotives, the valve angle is 300, whereas in conventional locomotives it is 450. The head is completely dismantled and after cleaning and mating the val ve & valve seat and overhauling the complete components, the head is made ready for service in this section after various tests. The staff strength of this section is about 7. 5.6. Cross Head Section:Crosshead is a subassembly, which is operated by camshaft to operate the valve lever mechanism of the cylinder heads. There are 16 cross heads in one locomotive. The cross heads operate the valve levers through two bush rods, one for exhaust and other for air inlet. Cross heads are completely dismantled and overhauled and also the valve lever mechanism is completely dismantled and overhauled in this section. The staff strength of this section is about 4. 5.7. Pump Section:The pump section is responsible for overhauling water pump and lube oil pump of the locomotive. Both the pumps are gear driven through crankshaft split gear train.Every loco is having one water pump and one no. lubricating oil pump. Both the pumpsare cleaned, overhauled and made ready for service in this section. The staff strength of this section is 4 5.8. Miscelleneous Sub-assembly & Heat Exchanger Section:This section is responsible for maintaining rear truck traction motor blower which is belt driven, front truck traction motor blower which is gear driven, universal shaft, which is used to drive radiator fan, eddy current clutch gear box used to provide drive to radiator fan, over speed trip assembly is responsible for preventing the 18 engine from over-speeding. In addition to above, various heat exchangers, such as radiator, turbo a f t e r c o o l e r , c o m p r e s s o r a f t e r c o o l e r a n d e n g i n e l u b e o i l c o o l e r a r e c l e a n e d , t e s t e d & overhauled in this section. The self-centrifuging unit of locomotive is also overhauled in this section. 5.9.Bogie Section:This section is responsible for complete overhauling of under gear of the locomotive. A locomotive is driven on line through 06 No. traction motors, which are supplied from a generator driven by the diesel engine. These motors are fitted on 6 Nos. axles and connected to axles through a bull gear pinion arrangement. They are suspended through suspension bearing which is plain bearing in some loco m o t i v e s , whereas these are roller bearings in about 50% of locomotives. Two bogie frames are used to house six axles and wheels and called as front bogie and rear bogie. The braking arrangement for the locomotives is given through 8 brake cylinders, 4 on each bogie and various brake riggings, brake shoes and brake blocks. The load of locomotive is shared by each bogie. Each bogie has two nos. side bearers and one no. central pivot. The load sharing between the central pivot and the side bearer is in the ratio of 60:40. The chassis of the locomotive is having 2 Nos. central buffer couplers on each side for connection to t h e t r a i n . The chassis is also having mounted 4 Nos. buffers, 2 on each side to b e a r various pumps during operation. Staff strength in this section is about 70. 5.10. Yearly Section:Yearly section is used for complete overhauling of locomotive, engine block and removal of various mechanical subassemblies. The yearly section carries out 24m o n t h l y a n d 48 monthly schedules of the locomotives in which engine and various subassemblies are overhauled completely. Staff strength of this section is about 90. 5.11. Air Brake Section:Air brake section is responsible for overhauling of brake valves of air brake system and other safety items such as wipers, sanders, horns etc. In addition to it, various gauges are also being maintained by this section. Staff strength of this section is about 50. 5.12. Valve Section:This section is responsible for maintaining fuel regulating valve, fuel relief valve, lube oil regulating valve, lube oil relief valve, lube oil bypass valve of the locomotive.T h e v a l v e s a r e o v e r h a u l e d a n d a r e s e t a t a r e q u i r e d p r e s s u r e a s p e r M a i n t e n a n c e Instructions. Staff strength of this section is 2. 19 5.13. Speedometer Section:The speedometer section is responsible for maintaining speedometers of thel o c o m o t i v e , w h i c h a r e r e s p o n s i b l e f o r r e c o r d i n g a n d i n d i c a t i n g t h e s p e e d o f t h e locomotive. Staff strength of this section is about 16. 5.14. Governor Section:Governor section is responsible for maintenance of governor of the locomotive.The governor of the locomotive is responsible for maintaining constant speed of the engine as per requirement at every notch. At present, the shed has 3 types of governors. ( i ) W o o d w a r d g o v e r n o r (ii)GE or electro hydraulic governor (iii)Microprocessor based governor 20 CHAPTER 6 PRODUCT OF THE INDUSTRY 21 .SCHEMATIC DIAGRAM OF DIESEL – ELECTRICLOCOMOTIVE FIG 6 .SCHEMATIC DIAGRAM OF DIESEL – ELECTRICLOCOMOTIVE 22 BLOCK DIAGRAM OF DIESEL LOCOMOTIVE Fig 7. BLOCK DIAGRAM OF DIESEL LOCOMOTIVE A Diesel locomotive is a type of railroad locomotive in which prime mover is a diesel locomotive. Types of Diesel locomotives WDM2 WDM3 WDF6 WDV6 2600HP 3100HP 1350HP 4000HP The first few prototype WDM-2s were imported. After Diesel Locomotive Works (DLW) completed construction of its factory in Varanasi, production of the locomotives b e g a n i n India. The first 12 locos were built using kits imported from ALCO in the United States. After that DLW started manufacturing the WDM-2 locomotives from their own components. Since then over 2,800 locomotives have been manufactured and theWDM-2 has become the most popular locomotive in India. However, even before the arrival of WDM-2 another type of diesel locomotivewas imported from ALCO beginning in 1957. This locomotive was classified as WDM-1. Later a number of modifications were made and a few subclasses were created. 23 This includes WDM-2A, WDM-2B and WDM-3A (formerly WDM-2C).The WDM-2 is the diesel workhorse of the Indian Railways, being very reliable and rugged T h e c l a s s W D M - 2 i s Indian Railways' work horse diesel locomotive. T h e f i r s t units were imported fully built from the American Locomotive Company(Alco) in1962.Since1964,it has been manufactured in India by the Diesel Locomotive Works(DLW),Varanasi. The model name stands for broad gauge(W), diesel (D), mixed traffic (M)engine. The WDM-2 is the most common diesel locomotive of Indian Railways. The WDM-2A is a variant of the original WDM-2. These units have been retrofitted with air brakes, in addition to the original vacuum brakes. The WDM-2B is a more recent locomotive, built with air brakes as original equipment. The WDM-2 locos have a maximum speed of 120km/h(75 mph), restricted to 100 km/h (62 mph) when run long hood forward. The gear ratio is 65:18. Technical specifications 24 The above requirement, in the year 1987, led to the creation of test beds at Engine D e v e l o p m e n t D i r e c t o r a t e o f R D S O a t L u c k n o w h a v i n g s t a t e o f t h e a r t f a c i l i t i e s f o r developmental testing of all the variants of diesel engines being used by Indian Railways. It included the computer based test facility for both data logging and control of engines The above facilities comparable to the best facilities in the world were created to meet the following objectives: Development of technology for improving existing Rail Traction Diesel Engines for 1. Better Fuel Efficiency 2. Higher Reliability 3. Increased Availability Development of technology for increasing power output of existing Diesel Engines. Develop capability for designing new Rail Traction Diesel Engines for meeting future needs of Indian Railways. To provide effective R&D backup to Railways and Production units to 1. Maintain Quality 2. Facilitate Indigenization 2.Broad Gauge Main Line Freight Locomotive WDG 3A Fig 8. WDG 3A 25 Technical Information Diesel Electric main line, heavy duty goods service locomotive, with 16 cylinder ALCO engine and AC/DC traction with micro processor controls. 3.Broad Gauge Main Line Mixed Service LOCO WDM 3D Fig 9.WDM 3D 26 Technical Information Diesel Electric Locomotive with micro processor control suitable for main line mixed Service train operation 3.Broad Gauge Shunting Locomotive WDS 6AD Fig 10.WDS 6AD 27 Technical Information A heavy duty shunting Diesel Electric Locomotive for main line and branch line train operation. This locomotive is very popular with Steel Plants and Port Trusts Engine Test Bed Facilities The test bed facilities in RDSO are equipped with four Test Cells. These Test Cells house four (16 cylinders GMEMD, 16 cylinders ALCO, 12 cylinders ALCO, 6 cylinders ALCO) types of DLW manufactured Engines. Each test cell has its own microprocessor c o n t r o l l e d d a t a a c q u i s i t i o n a n d c o n t r o l s ys t e m s a n d V i d e o D i s p l a y U n i t ( V D U ) f o r pressure, temperature and other parameters. Various transducers relay the information from the test engines to the microprocessor based test commander for further processing with the help of sophisticated software. Each test cell has an instrumentation catering to60 to 120 pressures / temperature transducers along with sophisticated equipments like gravimetric fuel balance for measurement of fuel consumption and the equipment for measurement of air flow. 28 Fig 11. Test Bed Fuel Consumption on 8th Notch Since the fuel consumption at 8th notch is highest and also since Locomotives run at this notch for longer duration as compared to other notches, fuel consumption at this notch is one of the important fuel efficiency index. This is measured in terms of gm / bhp- hr Fuel Consumption Over Duty Cycle An Engine runs in the field at different notch as per requirement of speed / load of the locomotive. The notch wise percentage running of locomotive over duty cycle for passenger and freight operations of Indian Railways locomotives is as under Speed at different Notch position NOTCH 1 2 3 4 5 6 7 8 SPEED(RPM) 400 450 550 650 750 850 915 1000 29 Driving a Locomotive You don't just hop in the cab, turn the key and drive away in a diesellocomotive.Starting a train is a little more complicated than starting your car. The engineer climbs an 8-foot (2.4-m) ladder and enters a corridor behind the cab. He or she engages a knife switch (like the ones in old Frankenstein movies) that connects the batteries to the starter circuit. Then the engineer flips about a hundred switches on a circuit-breaker panel, providing power to everything from the lights to the fuel pump. Next, the engineer walks down a corridor into the engine room. He turns and holds a switch there, which primes the fuel system, making sure that all of the air is out of the system. He then turns the switch the other way and the starter motor engages. The engine cranks over and starts running Next, he goes up to the cab to monitor the gauges and set the brakes o n c e t h e compressor has pressurized the brake system. He can then head to the back of the train to release the hand brake. Finally he can head back up to the cab and take over control from there. Once he has permission from the conductor of the train to move, he engages the bell, which rings continuously, and sounds the air horns twice (indicating forward motion). The throttle control has eight positions, plus an idle position. Each of the throttle positions is called a "notch. " N o t c h 1 i s t h e s l o w e s t s p e e d , a n d n o t c h 8 i s t h e h i g h e s t speed. To get the train moving, the engineer releases the brakes and puts the throttle into notch 1. In this General Motors EMD 710 series engine, putting the throttle into notch 1engages a set of contactors (giant electrical relays) . T h e s e c o n t a c t o r s h o o k t h e maing e n e r a t o r t o t h e t r a c t i o n m o t o r s . E a c h n o t c h e n g a g e s a d i f f e r e n t c o m b i n a t i o n o f contactors, producing a different voltage. Some combinations of contactors put certain parts of the generator winding into a series configuration that results in a higher voltage. Others put certain parts in parallel, resulting in a lower voltage. The traction motors produce more power at higher voltages. As the contactors engage, the computerized engine controls adjust the fuel injectors to start producing more engine power 30 Main Parts Of An Engine 1. Main Alternator The diesel engine drives the main alternator which provides the power to move the train. The alternator generates AC electricity which is used to provide power for the traction motors mounted on the trucks (bogies). In older locomotives, the alternator was a DC machine, called a generator. It produced direct current which was used to provide power for DC traction motors. Many of these machines are still in regular use. The next development was the replacement of the generator by the alternator but still using Detraction motors. The AC output is rectified to give the DC required for the motors. 2.Auxiliary Alternator Locomotives used to operate passenger trains are equipped with an auxiliarya l t e r n a t o r . T h i s p r o v i d e s A C p o w e r f o r l i g h t i n g , h e a t i n g , a i r c o n d i t i o n i n g , d i n i n g facilities etc. on the train. The output is transmitted along the train through an auxiliary power line. In the US, it is known as "head end power" or "hotel power". In the UK, air conditioned passenger coaches get what is called electric train supply (ETS) from the auxiliary alternator 3.Motor Blower The diesel engine also drives a motor blower. As its name suggests, the motor blower provides air which is blown over the traction motors to keep them cool during p e r i o d s o f heavy work. The blower is mounted inside t h e l o c o m o t i v e b o d y b u t t h e motors are on the trucks, so the blower output is connected to each of the motors through flexible ducting. The blower output also cools the alternators. Some designs have separate blowers for the group of motors on each truck and others for the alternators. Whatever the arrangement, a modern locomotive has a complex air management system which monitors the temperature of the various rotating machines in the locomotive and adjusts the flow of air accordingly 4.Air Intakes The air for cooling the locomotive's motors is drawn in from outside the locomotive. Ith a s t o b e f i l t e r e d t o r e m o v e d u s t a n d o t h e r i m p u r i t i e s a n d i t s f l o w r e g u l a t e d b y temperature, both inside and outside the locomotive. The air management system has to take account of the wide range of temperatures from the possible +40° C of summer to the possible -40° C of winter. 31 5.Rectifiers/Inverters The output from the main alternator is AC but it can be used in a locomotive with either DC or AC traction motors. DC motors were the traditional type used for many years but, in the last 10 years, AC motors have become standard for new locomotives. They are cheaper to build and cost less to maintain and, with electronic management can be very finely controlled. To see more on the difference between DC and AC traction technology try the Electronic on this site. To convert the AC output from the main alternator to DC, rectifiers are required. If the motors are DC, the output from the rectifiers is used directly. If the motors are AC, the DC output from the rectifiers is converted to 3-phase AC for the traction motors. In the US, there are some variations in how the inverters are configured. GMEMD relies on one inverter per truck, while GE uses one inverter per axle - both systems have their merits. EMD's system links the axles within each truck in parallel, ensuring wheel slip control is maximized among the axles equally. Parallel control also means even wheel wear even between axles. However, if one inverter (i.e. one truck) fails then the unit is only able to produce 50 per cent of its tractive effort. One inverter per axle is more complicated, but the GE view is that individual axle control can provide the best tractive effort. If an inverter fails, the tractive effort for that axle is lost, but full tractive e f f o r t is still available through the other five inverters. By controlling each axle individually, keeping wheel diameters closely matched for optimum performance is no longer necessary 6.Electronic Controls: Almost every part of the modern locomotive's equipment has some form of electronic control. These are usually collected in a control cubicle near the cab for easy access. The controls will usually include a maintenance management system of some sort which can be used to download data to a portable or hand-held computer. Fig.12 Controls, indicators and the radio 7. Controls Stand: This is the principal man-machine interface, known as a control desk in the UK or control stand in the US. The common US type of stand is positioned at an angle on the left side of the driving position and, it is said, is much preferred by drivers to the modern desk type of control layout usual in Europe and now being offered on some locomotives in the US. 32 8.Batteries Just like an automobile, the diesel engine needs a battery to start it and to provide electrical power for lights and controls when the engine is switched off and the alternator is not running. The locomotive operates on a nominal 64 -volt electrical system. The locomotive has eight 8-volt batteries; each weighing over 300 pounds (136 kg). These batteries provide the power needed to start the engine (it has a huge starter motor), as well as to run the electronics in the locomotive. Once the main engine is running, an alternator supplies power to the electronics and the batteries. 9. Cab: Most US diesel locomotives have only one cab but the practice in Europe is twoc a b s . U S f r e i g h t l o c o s a r e a l s o d e s i g n e d w i t h n a r r o w e n g i n e c o m p a r t m e n t s a n d walkways along either side. This gives a reasonable forward view if the locomotive is working "hood forwards". US passenger locos, on the other hand have full width bodies and more streamlined ends but still usually with one cab. In Europe, it is difficult to tell the difference between a freight and passenger locomotive because the designs are almost all wide bodied and their use is often mixed. The cab of the locomotive rides on its own s u s p e n s i o n s ys t e m , w h i c h h e l p s i s o l a t e t h e e n g i n e e r f r o m b u m p s . T h e s e a t s h a v e a suspension system as well. 10.Traction Motor: Since the diesel-electric locomotive uses electric transmission, traction motors are provided on the axles to give the final drive. These motors were traditionally DC but the development of modern power and control electronics has led to the introduction of 3 phase AC motors. There are between four and six motors on most diesele l e c t r i c locomotives. A modern AC motor with air blowing can provide up to 1,000 hp. 33 \ Fig.13 Traction Motor Description 11.Propulsion: The traction motors provide propulsion power to the wheels. There is one on each axle. Each motor drives a small gear, which meshes with a larger gear on the axles haft. This provides the gear reduction that allows the motor to drive the train at speeds of up to Each motor weighs 6,000 pounds (2,722 kg) and can draw up to 1,170 amps of electrical current. 12.Fuel Tank A diesel locomotive has to carry its own fuel around with it and there has to be enough for a reasonable length of trip. The fuel tank is normally under the loco frame and will have a capacity of say 1,000 imperial gallons (UK Class 59, 3,000 hp) or 5,000US gallons in a General Electric AC4400CW 4,400 hp locomotive. The new AC6000shave 5,500 gallon tanks. In addition to fuel, the locomotive will carry around, typically about 300 US gallons of cooling water and 250 gallons of lubricating oil for the diesel engine. Air 34 reservoirs are also required for the train braking and some other sys tems on the locomotive. These are often mounted next to the fuel tank under the floor of the locomotive. This huge tank in the underbelly of the locomotive holds 2,200 gallons (8,328 L)of diesel fuel. The fuel tank is compartmentalized, so if any compartment is damaged or starts to leak, pumps can remove the fuel from that compartment. 13.Governor Once a diesel engine is running, the engine speed is monitored and controlled through a governor. The governor ensures that the engine speed stays high enough to idle at the right speed and that the engine speed will not rise too high when full power is demanded. The governor is a simple mechanical device which first appeared on steam engines. It operates on a diesel engine as shown in the diagram below. The governor consists of a rotating shaft, which is driven by the diesel engine. A pair of flyweights is linked to the shaft and they rotate as it rotates. The centrifugal force caused by the rotation causes the weights to be thrown outwards as the speed of the shaft rises. If the speed falls the weights move inwards. The flyweights are linked to a collar fitted around the shaft by a pair of arms. As the weights move out, so the collar rises on the shaft. If the weights move inwards, the collar moves down the shaft. The movement of the collar is used to operate the fuel rack lever controlling the amount of fuel supplied to the engine by the injectors Fig.14 Governer Function and types of governors The purpose of a governor is to control the speed of an engine. If an engine is loaded beyond its rated capacity, it will slow down or may even stop. Governors act through thef u e l i n j e c t i o n s y s t e m t o c o n t r o l t h e a m o u n t o f f u e l d e l i v e r e d t o t h e c yl i n d e r s . T h e quantity of fuel delivered, in turn, governs the power developed. The two types of governors, each of which serves a distinctly different purpose, are over speed governor And regulating governor. T h e o v e r s p e e d t yp e i s u s e d o n m o s t marine engines where the speed of the engine is variable. By necessity, the marine engine requires flexibility in speed due to the maneuvering of the ship. This type of governor isi n s t a l l e d a s a s a f e t y m e a s u r e a n d c o m e s i n t o a c t i o n w h e n t h e e n g 35 i n e a p p r o a c h e s dangerous over speed. This condition could occur before the operator had time to bring t h e e n g i n e u n d e r c o n t r o l b y o t h e r m e a n s . T h e o v e r s p e e d t r i p f u n c t i o n s o n l y i f t h e regulating governor fails. This governor controls all abnormal speed surges For this discussion governors will be classified as either hydraulic or mechanical. The mechanical type embodies the principle of centrifugal force similar to the over speed type, while the hydraulic type employs a centrifugally actuated pilot valve to regulate the flow of a hydraulic medium under pressure. The mechanical governor is more applicable to the small engine field not requiring extremely close regulation while the hydraulic type finds favor with the larger installations demanding very close regulation. Theregulatingg o v e r n o r i s m u c h m o r e s e n s i t i v e t o s l i g h t s p e e d f l u c t u a t i o n s t h a n i s t h e o v e r s p e e d governor. Its duty is to control the speed within very narrow limits when an engine is operating under varying loads. It takes the place of the operator's manual control of the t h r o t t l e . W h e n t h e l o a d o n t h e e n g i n e i n c r e a s e s , a n d b e f o r e t h e e n g i n e ' s s p e e d h a s appreciably dropped, it permits an increase of fuel to the cylinders, thus maintaining the engine speed at the set rate. To perform this function, the governor must be sensitive to the slightest variation in speed. The Woodward hydraulic governor of the regulating type is widely used in the United States Navy & Railway Engines. 13.1 Description and operation: The type of regulating governor used on all submarine main engines is the W o o d w a r d S I h yd r a u l i c t yp e g o v e r n o r . O n F - M e n g i n e s , i t i s d r i v e n f r o m t h e l o w e r crankshaft, and on GM engines, from one of the camshafts. The purpose of the governor is to regulate the amount of fuel supplied to the cylinders so that a predetermined engine speed will be maintained despite variations in load. Figure 10-2 is a schematic diagram of t h e g o v e r n o r . T h e p r i n c i p a l p a r t s o f t h e g o v e r n o r a r e a g e a r p u m p a n d a c c u m u l a t o r s w h i c h s e r v e t o k e e p a c o n s t a n t o i l p r e s s u r e o n t h e s ys t e m a t a l l t i m e s ; a p i l o t v a l v e plunger, pilot valve bushing, and flyweights which control the amount of oil going to the power assembly; a speed adjusting spring whose tension governs the speed setting of the governor; the power element, consisting of the power spring, power piston, and power cylinder; and the compensating assembly which consists of compensating p l u n g e r , t h e r e c e i v i n g c o m p e n s a t i n g p l u n g e r , t h e c o m p e n s a t i n g s p r i n g , a n d t w o compensation needle valves. The pilot valve plunger is constructed with a land which serves to open or close the port in the pilot valve bushing leading to the power cylinder. In this governor the flyweights are linked hydraulically to the fuel control cylinder. The downward pressure of the power spring is balanced by the hydraulic lock o n t h e l o w e r s i d e o f t h e p o w e r p i s t o n . T h e a m o u n t o f o i l b e l o w t h e p o w e r p i s t o n i s regulated by the pilot valve plunger controlled by the flyweights. 36 When the engine is running at the speed set on the governor, the land on the pilot v a l v e plunger covers the regulating port in the bushing. The plunger is held in t h i s position by the flyweights. However, if the engine load decreases, the engine speeds up and the additional centrifugal force moves the flyweights outward, raising the pilot valve plunger. This opens the regulating port of the bushing, and trapped oil from the power cylinder is then allowed to flow through the pilot valve cylinder into a drainage passage to the oil sump. As the trapped oil drains to the oil sump, the power spring forces the piston down, actuating the linkage to the fuel system controls, and the supply of fuel to t h e e n g i n e i s d i m i n i s h e d . A s t h e e n g i n e s p e e d r e t u r n s t o t h e s e t r a t e , t h e f l y w e i g h t s résumé their original position and the, pilot valve plunger again covers the regulating port. When the engine is running at the speed set on the governor, the land on the pilot v a l v e p l u n g e r c o v e r s t h e r e g u l a t i n g p o r t i n t h e b u s h i n g . T h e p l u n g e r i s h e l d i n t h i s position by the flyweights. However, if the engine load decreases, the engine speeds up and the additional centrifugal force moves the flyweights outward, raising the pilot valve plunger. This opens the regulating port of the bushing, and trapped oil from the power cylinder is then allowed to flow through the pilot valve cylinder into a drainage passage to the oil sump. As the trapped oil drains to the oil sump, the power spring forces the piston down, actuating the linkage to the fuel system controls, and the supply of fuel to t h e e n g i n e i s d i m i n i s h e d . A s t h e e n g i n e s p e e d r e t u r n s t o t h e s e t r a t e , t h e f l yw e i g h t s résumé their original position and the, pilot valve plunger again covers the regulating port. Fig 15. Woodward regulating governor installed When the engine is running at the speed set on the governor, the land on the pilot v a l v e plunger covers the regulating port in the bushing. The plunger is held in t h i s position by the flyweights. However, if the engine load decreases, the engine speeds up and the additional centrifugal force moves the flyweights outward, raising the pilot valve plunger. This opens the regulating port of the bushing, and trapped oil from the power cylinder is then allowed to flow through the pilot valve cylinder into a drainage passage to the oil sump. As the trapped oil drains to the oil sump, the power spring forces the piston down, actuating the linkage to the fuel system controls, and the 37 supply of fuel to t h e e n g i n e i s d i m i n i s h e d . A s t h e e n g i n e s p e e d r e t u r n s t o t h e s e t r a t e , t h e f l y w e i g h t s résumé their original position and the, pilot valve plunger again covers the regulating port. Fig 16. Schematic diagram of Woodward regulating governor If the load increases, the engine slows down, and the flyweights move inward. This l o w e r s the pilot valve plunger, allowing pressure oil to flow through the pilot v a l v e chamber to the power cylinder. This oil supplied by a pump is under a pressure sufficient to overcome the pressure of the power spring. The power piston moves upward, actuating the linkage to increase the amount of fuel injected into the engine cylinders. Once again, as the speed returns to the set rate, the flyweights resume their central position. The gear pump that supplies the high-pressure oil is driven from the governor drive shaft and takes suction from the governor oil sump. A spring-loaded accumulator maintains a constant pressure of oil and allows excess oil to return to the sump. To prevent overcorrection in the regulating governor a compensating mechanisms used. This acts on the pilot valve bushing so as to anticipate the pilot valve movement and close the regulating port slightly before the centrifugal fly balls would normally direct t h e p i l o t v a l v e t o c o v e r t h e p o r t . A c o m p e n s a t i n g p l u n g e r o n t h e p o w e r p i s t o n s h a f t moves in a cylinder that is also filled with oil. When the engine speed increases and the power piston moves downward, the actuating compensating plunger is also carried down, drawing oil into its cylinder. This creates a suction above the receiving compensating plunger which is part of the pilot valve bushing. The bushing moves upward, closingthe p o r t t o t h e p o w e r p i s t o n . T h u s t h e p o w e r p i s t o n i s s t o p p e d , a l l o w i n g n o t i m e f o r overcorrection. As the flyweights an d pilot valve return to their central position, oil flowing through a needle valve allows the compensating spring to return to its central position. To keep the port closed, the bushing and plunger must return to normal position at exactly the same speed. Therefore, the needle valve must be adjusted so that the oil passes through at the required rate for the particular engine. 38 When the engine speed drops below the set rate, the actuating compensating p l u n g e r m o v e s u p w a r d w i t h t h e p o w e r p i s t o n . T h i s i n c r e a s e s which therefore moves down, carrying with it the pilot valve bushing. As before, the lower bushing port is closed. The excess oil in the compensating system is now forced out through the needle valve as the compensating spring returns the bushing to its central position. The governing speed of the engine is set by changing the tension of the speed adjustings p r i n g . T h e p r e s s u r e o f t h i s s p r i n g d e t e r m i n e s t h e e n g i n e s p e e d n e c e s s a r y f o r t h e flyweights to maintain their central position. Oil allowed to leak past the various plungers for lubricating purposes is drained into the governing oil sump. In actual operation, the events described above occur almost simultaneously. Regulating governor sub-assemblies:The governor consists of five principal subassemblies as follows: a. Drive adapter: T h e d r i v e a d a p t e r a s s e m b l y s e r v e s a s a m o u n t i n g b a s e f o r t h e governor. The upper flange of the casting is bored out at the center to form a bearing surface for the hub of the pump drive gear and for the upper end of the drive shaft. b. Power case assembly:T h i s a s s e m b l y i n c l u d e s t h e g o v e r n o r o i l p u m p , o i l p u m p check valves, oil pressure accumulators, and compensating needle valves. The oil pump drive gear turns the rotating sleeve to which it is attached. The pump idler gear is carried on a stud and rotates in a bored recess in the power case. These two gears and their housing constitute the governor oil pump. On opposite sides of the central bore in the power case, and parallel to it, are two long oil passages leading from the bottom of the power case to the top of the accumulator bores. Check valve seats are a r r a n g e d a t t h e t o p and bottom of each chamber. Both check valves have openings leading from the space between the valves to the oil pump. In t his way the pump i s arranged for rotation in either direction, pulling oil through the lower check valve on one side and forcing it through the upper check valve on the opposite side. There are two oil pressure accumulators. Their function is to regulate theo p e r a t i n g o i l p r e s s u r e a n d i n s u r e a c o n t i n u o u s s u p p l y o f o i l i n t h e e v e n t t h a t t h e requirements of the power cylinder should temporarily exceed the capacity of the oil pump. There is no adjustment for oil pressure, as this pressure is determined by the size of the springs in the accumulators. The two compensating needle valves control the size of the openings in the two small tapered ports in the passage that connects the 39 area above the actuating compensating plunger in the Servo motor and the space above the receiving compensating plunger in the pilot valve bushing of the rotating sleeve assembly. These ports open the compensating oil passage to the oil sump tank. Only one needle valve and one port are necessary for operation, but two are provided so that adjustment can be made on the one that is more accessible Fig. 17. Governor-sections through adapter, power, case, power cylinder and rotating sleeve assembly . c. Power cylinder assembly: The power cylinder assembly consists of the cylinder, power piston, piston rod, power spring, and the actuating compensating plunger. The power piston is single acting. Any oil pressure acting on the lower side forces the piston up against the power spring, thereby increasing the fuel flow. If no oil pressure is present, the power spring acting on the upper side forces the piston down to decrease the fuel flow. The area underneath the power piston is connected to the pilot valve regulating ports. An oil drain is provided in the space above the power piston to permit any oil that may leak by the piston to drain into the governor case oil sump. No piston rings are used in the closely fitting piston. A shallow, helical groove permits equal oil pressure on all sides of the piston, thus preventing wear and binding. 40 An adjustable load limit stop screw is provided in the power cylinder. This screw prevents the power piston from traveling beyond the predetermined load limit. The screw can be adjusted by removing the cap nut on top of the power cylinder, loosening the lock nut, and turning the screw up or down with a screwdriver. d. Speed control column:The basic speed control column assembly includes the speeder plug screw, speed adjusting spring, rack shaft, rack shaft gear, and the speed adjustment knob with gear train. The gear train consists of the dial shaft gear, dial shaft pinion, and the pinion shaft gear and pinion. H e n c e , t h e c o m p r e s s i o n d e t e r m i n e s t h e engine speed. The speeder plug screw allows the adjustment of the governor speed setting to match the actual speed of the engine. e. Rotating sleeve assembly: The principal parts of the rotating sleeve assembly are: t h e p u m p d r i v e g e a r , p i l o t v a l v e b u s h i n g , p i l o t v a l v e p l u n g e r , billhead, and fly balls. The central bore in the power case forms a bearing for the entire rotating sleeve. The port grooves in the sleeve align with the ports in the power case . T h e y e x t e n d c o m p l e t e l y a r o u n d t h e d i a m e t e r o f t h e rotating sleeve, the results are the same as if the sleeve was stationary and the ports were permanently in line with those in the case. From top to bottom the ports are as follows: accumulator pressure to pilot valve, regulating pressure to power cylinder, drain from the l o w e r e n d o f t h e p i l o t p l u n g e r , c o m p e n s a t i n g p r e s s u r e f r o m t h e p o w e r p i s t o n t o t h e receiving compensating plunger on the pilot valve bushing, and drain from the lower side of the receiving compensating plunger. 14.Air Compressor The air compressor is required to provide a constant supply of compressed air for the locomotive and train brakes. In the US, it is standard practice to drive the compressor off the diesel engine drive shaft. In the UK, the compressor is usually electrically driven and can therefore be mounted anywhere. The Class 60 compressor is under the frame, whereas the Class 37 has the compressors in the nose. 41 . Fig 18. Compressor 15.Gear Box: The radiator and its cooling fan is often located in the roof of the locomotive. Drive to the fan is therefore through a gearbox to change the direction of t h e d r i v e upwards . 16.Fuel Injection Ignition is a diesel engine is achieved by compressing air inside a cylinder until it gets very hot (say 400° C, almost 800° F) and then injecting a fine spray of fuel oil to cause a miniature explosion. The explosion forces down the piston in the cylinder and this turns the crankshaft. To get the fine spray needed for successful ignition the fuel has to be pumped into the cylinder at high pressure. The fuel pump is operated by a cam driven off the engine. The fuel is pumped into an injector, which gives the fine spray of fuel required in the cylinder for combustion. 42 Fig19. Fuel Injector The original fuel injection pumps used on ALCO Engines had plunger diameter of 15 mm. The plunger diameter of the fuel injection pump was increased from 15 mm to 17mm. This modification led to sharper fuel injection i.e. injection at higher-pressure. The modification resulted in increase of peak fuel line pressure from 750 to 850 bars and, thus, improvement in the fuel efficiency. The estimated fuel and lube oil economy with this modification is approx. 1.5%and 4% respectively 17.Radiator They are used for cooling internal combustion engines, chiefly in automobiles but also in piston-engined aircraft, railway locomotives, motorcycles, stationary generating plant or any similar use of such an engine .They operate by passing a liquid coolant through the engine block, where it is heated ,then through the radiator itself where it loses this heat to the atmosphere. This coolant is usually water-based, but may also be oil. It's usual for the coolant flow to be pumped ,also for a fan to blow air through the radiator. In railway with a liquidcooled internal combustion enginea radiator is connected to channels running through the engine and cylinder head, through which aliquid(coolant)is pumped. This liquid may be water (in climates where water is unlikely to freeze), but ism o r e c o m m o n l y a m i x t u r e o f w a t e r a n d antifreezein proportions appropriate to the climate. Antifreeze itself is usually ethylene glycolor propylene glycol(with a small amount of corrosion inhibitor ) 43 18.Turbo charger: A turbocharger, or turbo , is a gas compressor used for forced-induction of an internal combustion engine. L i k e a supercharger , t h e p u r p o s e o f a t u r b o c h a r g e r i s t o increase thedensityo f a i r e n t e r i n g t h e e n g i n e t o c r e a t e m o r e p o w e r . H o w e v e r , a turbocharger differs in that the compressor is powered by a turbinedriven by the engine's own exhaust gases Fig.20 Turbo Charger 19.Bogie: A bogie (pronounced/bogie/) is a wheeled wagon or trolley. In mechanics terms, a bogie is a chassis or framework carrying wheels, attached to a vehicle. It can be fixed in place, as on a cargo truck, mounted on a swivel, as on a railway carriage or locomotive, or sprung as in the suspension of a caterpillar tracked vehicle.Archbar type truck with journal bearings as used on some steam locomotive tenders. Fig21.Bogie 44 20.Transmission: Like an automobile, a diesel locomotive cannot start itself directly from a stand. It will n o t d e v e l o p m a x i m u m p o w e r a t i d l i n g s p e e d , s o i t n e e d s s o m e f o r m o f t r a n s m i s s i o n system to multiply torque when starting. It will also be necessary to vary the power applied according to the train weight or the line gradient. There are three methods of doing this: mechanical, hydraulic or electric. Most diesel locomotives use electric transmission and are called "dieselelectric" locomotives. Mechanical and hydraulic t r a n s m i s s i o n s a r e s t i l l u s e d b u t a r e m o r e c o m m o n o n m u l t i p l e u n i t t r a i n s o r l i g h t e r locomotives. Mechanical Transmission A diesel-mechanical locomotive is the simplest type of diesel locomotive. As then a m e s u g g e s t s , a m e c h a n i c a l t r a n s m i s s i o n o n a d i e s e l l o c o m o t i v e c o n s i s t s a d i r e c t mechanical link between the diesel engine and the wheels. In the example below, thed i e s e l e n g i n e i s i n t h e 3 5 0 - 5 0 0 h p r a n g e a n d t h e t r a n s m i s s i o n i s s i m i l a r t o t h a t o f a n automobile with a four speed gearbox. Most of the parts are similar to the diesel-electriclocomotive but there are some variations in design mentioned below 21.Brakes A common option on Diesel-electric locomotives is dynamic. Dynamic braking takes advantage of the fact that the traction motor armatures are always r o t a t i n g w h e n t h e l o c o m o t i v e i s i n m o t i o n a n d t h a t a m o t o r c a n b e m a d e t o a c t a s a generator by separately exciting the field winding. When dynamic braking is utilized, thetraction control circuits are configured as follows: The field winding of each traction motor is connected across the main generator. The armature of each traction motor is connected across a forceda i r c o o l e d resistance(the dynamic braking grid) in the roof of the locomotive's hood. 45 The prime mover RPM is increased and the main generator field is e x c i t e d , causing a corresponding excitation of the traction motor fields Fig 22 Air Brake System Ultimately, the source of the energy dissipated in the dynamic braking grid is the motion of the locomotive as imparted to the traction motor armatures. Therefore, the traction motors impose drag and the locomotive acts as a brake. As speed decreases, the braking effect decays and usually becomes ineffective below approximately 16km/h(10mph), depending on the gear ratio between the traction motors and axles. D yn a m i c b r a k i n g i s p a r t i c u l a r l y b e n e f i c i a l w h e n o p e r a t i n g i n m o u n t a i n o u s regions, where there is always the danger of a runaway due to overheated friction brakes during descent (see also comments in the brake article regarding loss of braking due toi m p r o p e r t r a i n h a n d l i n g ) . I n s u c h c a s e s , d y n a m i c b r a k e s a r e u s u a l l y a p p l i e d i n conjunction with the air, the combined effect being referred to as braking. The use of blended braking can also assist in keeping the slack in a long train stretched asit crests a grade, helping to prevent a "run-in," an abrupt bunching of train slack that can cause a derailment. Blended braking is also commonly used with commuter wear and tear on the mechanical brakes that is a natural result of the numerous stops such trains typically make during a run Vacuum brake: The vacuum brake is a braking system used on trains. It was first introduced in the mid1860s and a variant, the automatic vacuum brake system became almost universal in British train equipment, and in those countries influenced by British practice. It enjoyed a brief period of adoption in thousand, primarily on railroads. Its limitations caused it to be progressively superseded by compressed air systems, in the Kingdom from the 1970's.The vacuum brake 46 system is now obsolescent; it is not in large-scale use anywhere in the world, supplanted in the main by air Fig 23.Vaccum Brake Controller Dual brakes: Vehicles can be fitted with dual brakes, vacuum and air, provided that there is room to fit t h e duplicated equipment. It is much easier to fit one kind of brake with a p i p e f o r continuity of the other. Train crew need to take note that the wrong-fitted wagons do not contribute to the braking effort and make allowances on down grades to suit. Many of the earlier classes of R a i l w a ys w e r e f i t t e d w i t h d u a l systems to enable full usage of BR's rolling stock inherited from the private companies which had different systems depending on which company the stock originated from. When spring brakes are added to a dual air brake system, the same type of dash control valve discussed previously is used. Blended air is used to supply the spring parking brake c o n t r o l v a l v e ( 2 7 ) . B l e n d e d a i r i s a i r t a k e n f r o m t h e p r i m a r y a n d s e c o n d a r y c i r c u i t s through a two–way check valve (26). With this piping arrangement the vehicle can have failure in either circuit without the spring brakes applying automatically. If air is lost in both circuits, the spring brakes will apply. Air brakes need a tap to seal the hose at the ends of the train. If these taps are incorrectly closed, a loss of brake force may occur, leading to a dangerous runaway. With vacuum brakes, the end of the hose can be plugged into a stopper which seals the hose by suction. It is much harder to block the hose pipe compared to air brakes Twin pipe: Vacuum brakes can be operated in a twin pipe mode to speed up applications and release. Braking is provided by a mechanism that is similar to a car drum brake. An air-powered piston pushes a pad against the outer surface of the train wheel. In conjunction with the mechanical brakes, the locomotive has dynamic braking. In this mode, each of the four traction motors acts like a generator, using the wheels of the train to apply torque to the motors and generate electrical current. The torque that the wheels apply to turn the motors slows the train down (instead of the motors turning the 47 wheels, the wheels turn the motors). The current generated (up to 760 amps) is routed into a giant resistive mesh that turns that current into heat. A cooling fan sucks air through the mesh and blows it out the top of the locomotive -- effectively the world's most powerful hair dryer. On the rear truck there is also a hand brake -- yes, even trains need hand brakes. Since the brakes are air powered, they can only function while the compressor is running. If the train has been shut down for a while, there will be no air pressure to keep the brakes engaged. Without a hand brake and the failsafe of an air pressure reservoir, even a slight slope would be enough to get the train rolling because of its immense weight and the very low rolling friction between the wheels and the track. The hand brake is a crank that pulls a chain. It takes many turns of the cra nk to tighten the chain. The chain pulls the piston out to apply the brakes. AIRBRAKE EQUIPMENT In addition to the compressor, governor, reservoirs, and valves previously mentioned, all airbrake systems have many other parts. Typical examples are the cutout cocks; pressure gages; equalizing reservoir; distributing, feed, reducing, and quick release valves; and dead man control. These are discussed in the following subparagraphs. a. Cutout cocks are used to bypass parts of the circuit when they are not needed. b. Two pressure gages are common in airbrake systems. One indicates main air reservoir and equalizing reservoir pressures; the other shows locomotive brake cylinder and brake pipe pressures. c. An equalizing reservoir adds volume to the space above the equalizing piston in the brake valve so that reductions in brake pipe pressure may be properly made during service applications of the brakes. d. The distributing valve, when actuated by the brake valves, permits air to flow to the locomotive brake cylinders, maintains pressure against leakage when brakes are held in applied position, or permits air to exhaust to the atmosphere when brakes are released. e. A feed valve automatically maintains a predetermined air pressure in the brake pipe. f. A reducing valve reduces main reservoir pressure for independent airbrake operation or for an air signal system. g. A quick release valve provides a rapid release of brake cylinder pressure during the release operation. h. Dead man control is a safety device which must be pressed when the locomotive is in operation. It is released only when the brakes are to be applied. Release of the dead man pedal causes a warning whistle to sound for approximately 4 seconds after which the brakes are automatically applied; automatic application of the brakes can be avoided if the pedal is pressed again during the warning period. 48 ENGINE Engine Control Development: So far we have seen a simple example of diesel engine control but the systems used by most locomotives in service today are more sophisticated. To begin with, the drivers control was combined with the governor and hydraulic control was introduced. One type of governor uses oil to control the fuel racks hydrau lically and another uses the fuel oil pumped by a gear pump driven by the engine. Some governors are also linked to the turbo charging system to ensure that fuel does not increase before enough turbocharged air is available. In the most modern systems, the governor is electronic and is part of complete engine management system. Power Control: The diesel engine in a dieselelectric locomotive provides the driv e f o r t h e m a i n alternator which, in turn, provides the power required for the traction motors. We can see from this therefore, that the power required from the diesel engine is related to the power required by the motors. So, if we want more power from the motors, we must get more current from the alternator so the engine needs to run faster to generate it. Therefore, to get the optimum performance from the locomotive, we must link the control of the diesel engine to the power demands being made on the alternator. In the days of generators, a complex electro-mechanical system was developed to achieve the feedback required to regulate engine speed according to generator demand. The core of the system was a load regulator, basically a variable resistor which was used to very the excitation of the generator so that its output matched engine speed. The control sequence (simplified) was as follows:1.Driver moves the power controller to the full power position 2.An air operated piston actuated by the controller moves a lever, which closes as witch to supply a low voltage to the load regulator motor.3 . T h e l o a d r e g u l a t o r m o t o r m o v e s t h e v a r i a b l e r e s i s t o r t o i n c r e a s e t h e m a i n generator field strength and therefore its output.4 . T h e l o a d on the engine increases so its speed falls and the governor detects the reduced speed.5.The governor weights drop and cause the fuel rack servo system to actuate.6.The fuel rack moves to increase the fuel supplied to the injectors and therefore the power from the engine.7 . T h e l e v e r ( m e n t i o n e d i n 2 a b o v e ) i s u s e d t o r e d u c e t h e p r e s s u r e o f t h e g o v e r n o r spring.8 . W h e n t h e e n g i n e h a s r e s p o n d e d t o t h e n e w c o n t r o l a n d g o v e r n o r s e t t i n g s , i t a n d the generator will be producing more power. On locomotives with an alternator, the load regulation is done electronically. Engine speed is measured like modern speedometers, by counting the frequency of the gear teeth driven by the engine, in this case, the starter motor gearwheel. Electrical control of the fuel injection is another improvement now adopted for modern engines. Overheating can be controlled by electronic monitoring of coolant temperature and regulating the engine power accordingly. Oil pressure can be monitored and used to regulate the engine power in a similar way. 49 Fig 24Cylinder Block. ENGINE ACTION To produce power through an interval of time, a diesel engine must perform a definite series of operations over and over again. This series is known as a cycle in which suction, compression, ignition, and exhaust take place in the order listed. If the engine requires four strokes of the piston and two revolutions of the crankshaft to complete a cycle, it is known as a four-stroke-cycle engine; one completing the cycle in two strokes of the piston and one revolution of the crankshaft is a twostroke cycle engine. In the four-stroke-cycle engine, air is drawn into the cylinder through the intake valve as the piston descends on the intake stroke. The intake valve then closes and the piston goes up on the compression stroke, compressing the air within the cylinder. Fuel is injected through the injector while the air is compressed, and combustion occurs. The combustion, with resultant pressure, drives the piston back down on the power stroke. The piston rises again on the exhaust stroke and expels the air through the exhaust valve, a process called scavenging. Piston action in the two-stroke cycle engine is basically the same. A difference in scavenging accounts for two strokes rather than four. Air entering the intake port pushes the oxygen-depleted air, left from the previous combustion, out through the exhaust valves. The compression stroke then occurs. 50 PRESSURE CHARGING Air ordinarily enters the cylinder at atmospheric pressure. The amount of fuel entering the cylinder is therefore limited because it has to be related to the amount of oxygen available to mix with it. If too much fuel enters the cylinder and is left unburned, it settles on the cylinder wall and piston and dilutes the lube oil film. This prevents a tight fit and causes leakage of air and loss of power. Therefore, the amount of entering fuel must be carefully regulated. Also, it must enter the cylinder so that the first fuel entering begins burning before the rest of the fuel enters, providing gradual, even combustion. If all the fuel enters the cylinder before ignition begins, it all burns at once--explodes--and a loud knock from the explosion, called combustion knock, occurs. A pressurecharged engine provides a method of putting more air, more fuel, and resulting greater power into the cylinder. By this method, sometimes called supercharging, power can be increased 50 percent in a four-stroke engine and 35 percent in a two-stroke engine. Extra air is made to enter the intake valve or intake port by compression. A number of air-compressing devices have been used to furnish supercharging air. The kind most commonly used on diesel-electric locomotives is the turbine compressor, operated by a gas turbine in the exhaust system. It is the most logical place for this turbine because a great deal of energy is wasted through exhaust of burned gases. Heat balance figures show the loss to be as much as 40 percent of the energy liberated from the fuel by combustion. This energy is captured to run the turbine which is connected to the compressor that delivers air under pressure to the engine. LUBRICATING SYSTEM Sometimes, oil is used for cooling as well as for lubricating. When this is done, a separate oil radiator with its own cooling fan is provided with the main radiator. Used for bearing lubrication, the oil's circulation rate is lower than when it is used for piston cooling and lubrication. Oil hits the underside of the piston in a fine spray. The crankshaft, end bearings, operating gear, and camshaft are lubricated by oil under pressure; oil without pressure, free return oil, lubricates the camshaft driving gears and cylinder walls. Contaminating particles can usually be filtered out. a. Contamination. Some contamination of oil is inevitable. For example, the oil itself will oxidize and form corrosive acids. These acids are prevented from harming the engine by additives which either keep the oil from oxidizing or provide a protective coating on the parts they touch. In addition, the oil should possess some detergent properties to keep the contaminating matter in suspension so that it will be drained off when the crankcase is drained. Contaminating materials found in the oil may be any of the following: metal bits caused by wear of the engine, carbonaceous particles resulting from fuel incorrectly burned or caused by breakdown of the oil itself, unburnt fuel, cooling water that has leaked in, and acid water caused by cooling of burnt gases which have passed by the piston. b. Filters. Oil circulation pumps are protected from contamination by gauze screens that remove the heavier substances from the oil; smaller particles are removed by metallic strainers made of very fine gauze, steel wool, or closely spaced plates. The finest materials and carbon carried in suspension in the oil are removed by absorbent filters made of special papers, cotton, or felt. Two methods of routing the oil through the filters are used: full - flow filtering, which passes all the oil through the filter; and bypass filtering where only a part of the oil is continuously bypassed through the filter. Full-flow filters have relief valves that can open to take the oil out of the filter's path when the pressure drop across the filter is excessive. 51 Fig 25 Engine Description 52 ACCESSORIES The locomotive engine supports various accessories such as the horn and windshield wiper. These are actuated by either mechanical or electrical means to parts of the engine. a. Bell. The signal bell is stationary with a movable clapper operated by an air valve located at the engineman's station. The bell is usually located under the floor behind the pilot or switchman's footboards on the right side of the front end of the locomotive. b. Horn. The horn, operated by air valves that allow air to be forced through the sounding device, is mounted on top of the cab and controlled by two pull cords above the control stand. One cord gives a soft tone and the other a full tone. The horn shutoff cock is in the air line above the floor in front of the controller. This air line supplies the horn valves with air. c. Speed recorder. The speed recorder, similar to a speedometer, can be operated hydraulically, mechanically, or electrically. d. Windshield wipers. Windshield wipers are operated by air from the compressed air system. They are controlled by valves over the cab windows and operate independently of each other. Windshield wipers should never be run on a dry window as dirt on the window will scratch the glass. e. Sanding system. A sanding system delivers sand between the wheel and the rail. It has three parts: the sand trap, the control valve, and the operating device. Sand is kept in a box and flows through the sand trap and pipe to the rail. In some locomotives, the sanding system can be operated by the automatic brake valve handle. In others, it is operated by hand. f. Temperature controls. On larger locomotives, water temperature in the engine cooling system is regulated automatically. When water temperature changes, a thermostat operates switches which activate fan motor contactors. As the temperature increases, a medium-speed relay closes; further increase closes a full-speed relay. If the temperature drops, the same operations take place in reverse order. Some engine-cooling fans are motor driven and receive their power from an alternating current generator. Various combinations of fan contactors provide for fan operation through the traction motor circuit. Power is transmitted to drive the cooling fans through a magnetic clutch called the eddy current clutch. Fan speed is varied by changing the excitation of field coils on the clutch. Other engine cooling fans are mechanically driven. g. Engine heaters. Oil-fired engine heaters are provided for operation in severely cold weather. The cooling, lubricating, and fuel oil systems and batteries must be warmed before starting the engine if prolonged layover has resulted in congealed fuel oil or lubricating oil. Continued operation of the heaters is often necessary after the engine is started. Special insulation of oil lines, tanks, and compartments is part of such an installation, often called a winterization system. The heaters use fuel from the main locomotive fuel oil system, but a small tank at the heater is automatically kept full. This reserve supply of fuel may even have to be heated before the heaters are started. After the heaters are operating, they supply heat through a hot water piping system or an exhaust gas system to the power plant and essential auxiliary equipment. An electric motor which obtains its power from the locomotive's auxiliary power lines drives a fuel pump, water circulating pump, and blower. The fuel oil is ignited in the fire pot by a continuous electric spark. The equipment does not eliminate the need of draining the cooling system or keeping it filled with an adequate antifreeze solution when the locomotive is shut down. 53 h. Cab heaters. Cab heaters are installed on most locomotives to keep the cab comfortable in cold weather. They heat with hot water, electricity, or hot air. The hot-water heater is connected to the engine water system which supplies the heat. A small electric fan is built into the heater to circulate air over the water coils and into the cab. The heater switch in the cab connects the fan to the auxiliary power lines. Fan speed can be varied by a rheostat incorporated with the switch. Cocks are provided for shutting off the flow of water and for draining the heaters. An all-electric heater is essentially the same as the hot-water heater except that the heating element is an electric coil. Electric defrosters, which work on the same principle, have a separate control switch. Hot-air heaters consist of ducts through which hot air from the engine radiators is forced to the cab and cab windows. 54 CHAPTER 7 OUTPUT OF TRAINING 55 OUTPUT OF TRAINING The opportunity to work with Indian Western Railway (Diesel Loco Shed ,Itarsi) provided a chance to learn about the process of maintenance & assembly of Diesel Locomotive. I have tried to give my best to the training. Many thanks are extended to Indian Western Railway (Diesel Loco Shed ,Itarsi) family. for allowing me to undertake my industrial training with them and then use the details of the training, I was involved in for inclusion in the training. I have incorporated all the relevant motivation principles especially through awareness towards process of maintenance or assembly. 56 CHAPTER 8 CONCLUSION 57 CONCLUSION There are many thing that I have experience and learned during the 15 days of my industrial Training in diesel loco shed ,Itarsi .The whole training period was very interesting, comprehensive understanding about real industry working condition and practice. All of this value experience and knowledge that I have gained were not only acquired through the direction in task given but also through other aspect of the training such as work observation , interaction with colleagues , superior and other third party related to the company .From what I have undergone, I am hundred percent agree that the industrial training program have achieve its entire primary objective .Its also the best ways to prepare student in facing the real working life .As a result of the program now I am more confidence to enter the employment world and build my future career. 58 LIST OF FIGURE Figure Fig1.Entrance of Diesel Shed Fig.2Maintence shed Fig 3.Color scheme of loco Fig 4. Organization Chart of Diesel Shed Fig 5.Organisation chart Railway Fig 6 .SCHEMATIC DIAGRAM OF DIESEL – ELECTRICLOCOMOTIVE Fig7.Block Diagram of Diesel locomotive Fig 8. WDG 3A Fig 9.WDM 3D Fig 10.WDS 6AD Fig 11. Test Bed Fig.12 Controls, indicators and the radio Fig.13 Traction Motor Description 16 17 27 28 30 31 32 34 35 39 PAGE NO Fig.14 Governer Fig 15. Woodward regulating governor installed Fig 16. Schematic diagram of Woodward regulating governor Fig. 17. Governor-sections through adapter, power, case, power cylinder and rotating sleeve assembly Fig 18. Compressor 40 42 42 45 47 59 Fig19. Fuel Injector Fig.20 Turbo Charger Fig21.Bogie Fig 22 Air Brake System 48 49 50 51 52 Fig 23.Vaccum Brake Controller Fig 24Cylinder Block. Fig 25 Engine Description 54 57 60 REFRENCE 1. 2. 3. 4. 5. 6. 7. www.google.com www.inndiarail/locoshed.com Maintenance handbook for Mechanical of Railway authority Employees& workers of Loco shed Itarsi Professors of Railway college Railway Training Institute,Itarsi,library www.wikipedia.com 61