TRAINING CERTIFICATE This is to certify that _____________________________ (Name) pursuing MECHANICAL ENGINEERING from DELHI TECHNOLOGICAL UNIVERSITY (formerly DCE) having roll number 2K8/ME/____ has done his winter training at Diesel Loco Shed Tughlakabad, DELHI from ____________to____________. The project work entitled “________________________________________________________”and “________________________________________________________”, embodies the original work done by him at the end of his winter training. Mr. Hari Om (C.I., D.T.C., Diesel Loco Shed) Tughlakabad, Delhi i|Page ACKNOWLEDGEMENT We take this opportunity to express our sincere gratitude to the people who have helped us in the successful completion of our industrial training and the project. We would like to show our greatest appreciation to the highly devoted technical staff, supervisors and officials of the Diesel Locomotive Shed, Tughlakabad. We are highly indebted to them for their tremendous support and help during the completion of our training and project. In particular, we are grateful to Mr Hari Om, C.I. (D.T.C.) of Diesel Locomotive Shed, Tughlakabad and the Principal of the Training School, who scheduled our training in the various departments and cells of the shed and handed out this project to us. We would like to thank all those people who directly or indirectly helped and guided us to complete our training and project in the Diesel Training Centre and various sections. ii | P a g e Contents CERTIFICATE ................................................................................................................................ i ACKNOWLEDGEMENT .............................................................................................................. ii List of Figures .............................................................................................................................. viii List of Tables .................................................................................................................................. x 1 2 INDIAN RAILWAY HISTORY ............................................................................................ 1 DIESEL SHED TUGHLAKABAD ........................................................................................ 3 2.1 ABOUT DIESEL SHED TUGHLAKABAD .................................................................. 4 AT A GLANCE ........................................................................................................ 5 2.1.1 2.2 SPECIAL MACHINES & PLANT .................................................................................. 6 Pit wheel lathe machine ............................................................................................ 6 Effluent Treatment Plant:- ........................................................................................ 6 2.2.1 2.2.2 2.3 TECHNICAL INNOVATIONS ....................................................................................... 6 RTTM Test Stand ..................................................................................................... 6 Test Stand for Opening Pressure of on Line lube oil Centrifuge:............................. 7 Expresser Crank Shaft Bearing Extractor ................................................................. 8 2.3.1 2.3.2 2.3.3 2.4 2.5 2.6 2.7 FUEL SECTION .............................................................................................................. 9 CONTROL ROOM ........................................................................................................ 10 CTA (Chief Technical Assistance) CELL ..................................................................... 11 TURBO SUPERCHARGER .......................................................................................... 13 INTRODUCTION .................................................................................................. 13 TURBO SUPERCHARGER AND ITS WORKING PRINCIPLE ........................ 14 MAIN COMPONENTS OF TURBO-SUPERCHARGER .................................... 15 ROTOR ASSEMBLY ............................................................................................. 15 LUBRICATING, COOLING AND AIR CUSHIONING ...................................... 16 AFTER COOLER ................................................................................................... 16 Fitments of higher capacity Turbo Supercharger- .................................................. 17 TURBO RUN –DOWN TEST................................................................................ 18 2.7.1 2.7.2 2.7.3 2.7.4 2.7.5 2.7.6 2.7.7 2.7.8 iii | P a g e 2.7.9 ROTOR BALANCING MACHINE ....................................................................... 18 2.7.10 ADVANTAGES OF SUPER CHARGED ENGINES ........................................... 18 2.7.11 Defect in Turbochargers ......................................................................................... 18 2.7.12 Must change components of Turbocharger............................................................. 19 2.8 FUEL OIL SYSTEM ..................................................................................................... 20 INTRODUCTION .................................................................................................. 20 FUEL OIL SYSTEM .............................................................................................. 20 CALIBRATION OF FUEL INJECTION PUMPS ................................................. 26 FUEL INJECTION NOZZLE TEST ...................................................................... 27 2.8.1 2.8.2 2.8.3 2.8.4 2.9 BOGIE ............................................................................................................................ 29 INTRODUCTION .................................................................................................. 29 Key Components Of a Bogie .................................................................................. 30 CLASSIFICATION OF BOGIE ............................................................................. 30 Failure and remedies in the bogie section:- ............................................................ 31 2.9.1 2.9.2 2.9.3 2.9.4 2.10 EXPRESSOR ................................................................................................................... 32 INTRODUCTION .................................................................................................. 32 2.10.1 2.10.2 WORKING OF EXHAUSTER .............................................................................. 33 2.10.3 Compressor ............................................................................................................. 33 2.11 SPEEDOMETER ........................................................................................................... 36 2.11.1 INTRODUCTION .................................................................................................. 36 2.11.2 WORKING MECHANISM .................................................................................... 36 2.11.3 Salient features ........................................................................................................ 37 2.11.4 Applications ............................................................................................................ 38 2.11.5 Technical Specifications ......................................................................................... 38 2.12 CYLINDER HEAD........................................................................................................ 40 2.12.1 INTRODUCTION .................................................................................................. 40 2.12.2 Components of cylinder head ................................................................................. 40 2.12.3 Benefits:- ................................................................................................................. 41 2.13 Maintenance and Inspection ........................................................................................... 42 2.13.1 Cleaning: ................................................................................................................. 42 2.13.2 Crack Inspection: .................................................................................................... 42 iv | P a g e 2.13.3 Hydraulic Test:........................................................................................................ 42 2.13.4 Dimensional check : ................................................................................................ 42 2.13.5 Straightness of valve stem: ..................................................................................... 42 2.13.6 Checks during overhauling: .................................................................................... 43 2.13.7 Blow by test: ........................................................................................................... 43 2.14 PIT WHEEL LATHE ..................................................................................................... 44 2.14.1 INTRODUCTION .................................................................................................. 44 2.14.2 Wheel turning.......................................................................................................... 44 2.14.3 CAUSES OF WHEEL SKIDDING- ...................................................................... 45 2.15 FAILURE ANALYSIS .................................................................................................. 47 2.15.1 INTRODUCTION .................................................................................................. 47 2.15.2 Metallurgical lab. .................................................................................................... 48 2.15.3 Swelling test ............................................................................................................ 48 2.15.4 Procedure ................................................................................................................ 49 2.15.5 Rubber ..................................................................................................................... 49 2.15.6 ULTRASONIC TESTING...................................................................................... 50 2.15.7 ZYGLO TEST ........................................................................................................ 50 2.15.8 RED DYE PENETRATION TEST (RDP) ............................................................. 51 2.16 SCHEDULED EXAMINATION ................................................................................... 52 2.16.1 INTRODUCTION .................................................................................................. 52 2.16.2 MINOR SCHEDULES ........................................................................................... 53 2.16.3 MAJOR SCHEDULES ........................................................................................... 54 2.17 YEARLY/MECHANICAL ............................................................................................ 56 2.17.1 Examination while Engine is running. .................................................................... 58 2.17.2 (38). Additional items for WDP1:- ......................................................................... 59 2.17.3 (39). Additional items for WDP2 locos:-................................................................ 59 3 Project Work ......................................................................................................................... 60 3.1 3.2 3.3 Introduction to bearing ................................................................................................... 61 Friction ........................................................................................................................... 62 Service life...................................................................................................................... 63 Fluid and magnetic bearings ................................................................................... 63 3.3.1 v|Page 3.3.2 3.3.3 3.3.4 3.3.5 3.3.6 3.3.7 3.4 Rolling element bearings ........................................................................................ 63 Plain bearings .......................................................................................................... 63 Flexure bearings ...................................................................................................... 63 Short-life bearings ................................................................................................... 64 L10 life .................................................................................................................... 64 External factors ....................................................................................................... 64 Classification of Bearings: ............................................................................................. 65 Fluid Film bearings: ................................................................................................ 65 Rolling contact bearings: ........................................................................................ 65 Comparison of bearing frictions: ............................................................................ 65 Sliding contact bearings - Advantages and Disadvantages: ................................... 66 3.4.1 3.4.2 3.4.3 3.4.4 3.5 Journal Bearing: ............................................................................................................. 67 Design parameters of journal bearing: .................................................................... 69 Selection of design zone: ........................................................................................ 69 3.5.1 3.5.2 3.6 Bearing Lubrication........................................................................................................ 71 Types of Lubrication ............................................................................................... 71 Stable Lubrication ................................................................................................... 72 3.6.1 3.6.2 3.7 General causes of bearing failure and Precautions......................................................... 74 DIRT: ...................................................................................................................... 74 INSUFFICIENT LUBRICATION.......................................................................... 75 MISASSEMBLY .................................................................................................... 77 IMPROPER MACHINING OF COMPONENTS. ................................................. 77 OVERLOADING ................................................................................................... 80 CORROSION ......................................................................................................... 80 CAVITATION ........................................................................................................ 81 3.7.1 3.7.2 3.7.3 3.7.4 3.7.5 3.7.6 3.7.7 3.8 Diesel Loco Specification .............................................................................................. 82 Diesel Locomotive Model: WDP3A....................................................................... 82 Diesel Locomotive Model: WDP1.......................................................................... 83 3.8.1 3.8.2 3.9 Main Bearing Failure Cases ........................................................................................... 84 Loco No. 14004: ..................................................................................................... 84 Loco No. 15530: ..................................................................................................... 84 3.9.1 3.9.2 vi | P a g e 3.9.3 3.9.4 Loco No. 15508: ..................................................................................................... 85 Loco No 15527: ...................................................................................................... 85 3.10 FINAL CONCLUSION of THE PROJECT .................................................................. 87 3.11 Ways to improve bearing life and performance ............................................................. 88 4 General Discipline ................................................................................................................ 90 4.1 4.2 4.3 Suggestions To Improve Performance of the Shed ........................................................ 90 Improvement in Working Conditions ............................................................................ 91 Reduction in Environmental Impact .............................................................................. 92 vii | P a g e List of Figures Figure 1-1: Chhatrapati Shivaji Terminus, Mumbai. First Railway Station in India. Also a world heritage site. .................................................................................................................................... 1 Figure 2-1: Diesel Shed Tughlakabad............................................................................................. 3 Figure 2-2: Diesel Shed Tughlakabad............................................................................................. 4 Figure 2-3: RTTM Test Stand......................................................................................................... 7 Figure 2-4: Test Stand for Opening Pressure of on Line lube oil Centrifuge ................................. 7 Figure 2-5: Closer look to test Stand for Opening Pressure of on Line lube oil Centrifuge .......... 8 Figure 2-6: Expresser Crank Shaft Bearing Extractor .................................................................... 8 Figure 2-7: Fuel tank ....................................................................................................................... 9 Figure 2-8: GE Turbocharger........................................................................................................ 17 Figure 2-9: Fuel Pump .................................................................................................................. 20 Figure 2-10: Fuel Injection Pump ................................................................................................. 21 Figure 2-11: Cut out section of assembled FIP ............................................................................. 23 Figure 2-12: Fuel Injection Nozzle ............................................................................................... 25 Figure 2-13: Diesel Engine Bogie................................................................................................. 29 Figure 2-14: Bo-Bo and Co-Co Bogies ........................................................................................ 30 Figure 2-15: Expressor .................................................................................................................. 32 Figure 2-16: Schematic Diagram of Expressor ............................................................................. 35 Figure 2-17: Speedometer and other gauges ................................................................................. 36 Figure 2-18: Block Diagram for speedometer Pulse..................................................................... 37 Figure 2-19: Telpro Speedometer Circuit ..................................................................................... 38 Figure 2-20: Cylinder Head .......................................................................................................... 40 Figure 2-21: Inspection of an engine ............................................................................................ 42 Figure 2-22: Pit Wheel Lathe Machine ......................................................................................... 44 Figure 2-23: Wheel Specifications................................................................................................ 45 Figure 2-24: A Failure Detection Device...................................................................................... 47 Figure 2-25: A Crankshaft taken out for Scheduled Examination ................................................ 52 Figure 2-26: Engine block taken out for yearly maintanence ....................................................... 56 Figure 3-1: Introduction to Bearings............................................................................................. 61 viii | P a g e Figure 3-2: Different Motions supported by Bearing ................................................................... 62 Figure 3-3: Bearing Service Life .................................................................................................. 64 Figure 3-4: Friction in Different Bearings .................................................................................... 66 Figure 3-5: Different Types of Journal Bearings .......................................................................... 67 Figure 3-6: Operation of a Journal Bearing .................................................................................. 68 Figure 3-7: Friction variation with Bearing Characteristic number.............................................. 69 Figure 3-8: Regimes of Lubrication .............................................................................................. 72 Figure 3-9: DIRT IN THE LUBRICATION SYSTEM ............................................................... 74 Figure 3-10: Dirt on Bearing Back ............................................................................................... 75 Figure 3-11: Bearing Failure due to Malfunctioning Lubrication ................................................ 76 Figure 3-12: Bearing Seizure due to oil film failure ..................................................................... 76 Figure 3-13: Failure due to misplaced oil hole of the bearing ...................................................... 77 Figure 3-14: Failure Due to Improperly Ground Housing ............................................................ 78 Figure 3-15: Failure due to Fillet Ride ......................................................................................... 78 Figure 3-16: Misaligned Shaft leads to Bearing Failure ............................................................... 79 Figure 3-17: Failure due to Insufficient Crush ............................................................................. 79 Figure 3-18: Bearing Failure due to Overloading ......................................................................... 80 Figure 3-19: Metal Fatigue caused by Overloading ..................................................................... 80 Figure 3-20: Bearing Corrosion due to wrong Lube Oil............................................................... 81 Figure 3-21: Cavitation in Bearing ............................................................................................... 81 Figure 3-22: Hydraulic Bolt Tensioner ......................................................................................... 89 Figure 4-1: Earmuffs reduce External Noise ................................................................................ 92 ix | P a g e List of Tables Table 1: List of Turbo Superchargers ........................................................................................... 17 Table 2: Calibration Value of different FIPs ................................................................................ 27 Table 3: Operating conditions....................................................................................................... 39 Table 4: Analogue indication ........................................................................................................ 39 Table 5: Digital indication ............................................................................................................ 39 Table 6: General ............................................................................................................................ 39 Table 7: Functions of some Alloying Materials ........................................................................... 48 x|Page 1 INDIAN RAILWAY HISTORY Figure 1-1: Chhatrapati Shivaji Terminus, Mumbai. First Railway Station in India. Also a world heritage site. Indian Railways is the departmental undertaking of the Government of India. It comes under the Ministry of Railways, Government of India. Indian Railways has one of the largest and busiest rail networks in the world, transporting over 30 million passengers and more than 2.8 million tonnes of freight daily. Its net income (2009-10) was over Rs. 9500 crore. It is the world's largest commercial employer, with more than 1.36 million employees. It operates rail transport on 7,500 stations over a total route length of more than 65,000 kilometres (40,389 miles). About 40% of the total track kilometre is electrified & almost all electrified sections use 25,000 V AC. The fleet of Indian railway includes over 240,000 (freight) wagons, 60,000 coaches and 9,000 locomotives. It also owns locomotive and coach production facilities. It was founded in 1853 under the East India Company. Indian Railways is administered by the Railway Board. Indian Railways is divided into 16 zones. Each zone railway is made up of a certain number of divisions. There are a total of sixty-seven divisions. It also operates the Kolkata metro. There are six manufacturing plants of the Indian Railways. Indian Railways use four rail track gauges:1. The broad gauge (1670 mm) 2. The meter gauge (1000 mm) 3. Narrow gauge (762 mm) 1|Page 4. Narrow gauge (610 mm). CLASSIFICATION Standard “Gauge” designations and dimensions: W = Broad gauge (1.67 m) Y = Medium gauge ( 1 m) Z = Narrow gauge (0.762 m) N = Narrow gauge (0.610 m) “Type of Traction” designations: D = Diesel-electric traction C = DC traction A = AC traction CA=Dual power AC/DC traction The “type of load” or “Service” designations: M= Mixed service P = Passenger G= Goods S = Shunting “Horse power” designations from June 2002 (except WDP-1 & WDM-2 LOCOS) ‘3’ For 3000 horsepower ‘4’ For 4000 horsepower ‘5’ For 5000 horsepower ‘A’ For extra 100 horsepower ‘B’ For extra 200 horsepower and so on. Hence „WDM-3A‟ indicates a broad gauge loco with diesel-electric traction. It is for mixed services and has 3100 horsepower. 2|Page 2 DIESEL SHED TUGHLAKABAD Figure 2-1: Diesel Shed Tughlakabad Diesel locomotive shed is an industrial-technical setup, where repair and maintenance works of diesel locomotives is carried out, so as to keep the loco working properly. It contributes to increase the operational life of diesel locomotives and tries to minimize the line failures. The technical manpower of a shed also increases the efficiency of the loco and remedies the failures of loco. The shed consists of the infrastructure to berth, dismantle, repair and test the loco and subsystems. The shed working is heavily based on the manual methods of doing the maintenance job and very less automation processes are used in sheds, especially in India. The diesel shed usually has: Berths and platforms for loco maintenance. Pits for under frame maintenance Heavy lift cranes and lifting jacks Fuel storage and lube oil storage, water treatment plant and testing labs etc. Sub-assembly overhauling and repairing sections Machine shop and welding facilities. 3|Page 2.1 ABOUT DIESEL SHED TUGHLAKABAD Figure 2-2: Diesel Shed Tughlakabad Diesel Shed, Tughlakabad of Northern Railway is located in NEW DELHI. The shed was established on 22nd April 1970. It was initially planned to home 75 locomotives. The shed cater the needs of Northern railway. This shed mainly provides locomotive to run the mail, goods and passenger services. No doubt the reliability, safety through preventive and predictive maintenance is high priority of the shed. To meet out the quality standard shed has taken various steps and obtaining of the ISO-9001-200O& ISO 14001 OHSAS CERTIFICATION is among of them. The Diesel Shed is equipped with modern machines and plant required for Maintenance of Diesel Locomotives and has an attached store depot. To provide pollution free atmosphere, Diesel Shed has constructed Effluent Treatment Plant. The morale of supervisors and staff of the shed is very high and whole shed works like a well-knit team. 4|Page 2.1.1 AT A GLANCE Inception: 22nd April1970 Present Holding: 147 Locomotives 19 WDM2 37 WDM3A 08 WDM3D 11 WDG3A 46 26 WDP1 WDP3A Accreditation ISO-9001-2000 & ISO 14001 Covered area of shed 10858 SQ. MTR Total Area of shed 1, 10,000 SQ. MTR Staff strength Sanctioned – 1357 On roll - 1201 Berthing capacity 17 locomotives 5|Page 2.2 SPECIAL MACHINES & PLANT 2.2.1 Pit wheel lathe machine This machine is suitable for turn & re-profiles the wheels of locomotives. 2.2.2 Effluent Treatment Plant:In order to provide pollution free environment, an ETP PLANT is installed. Various effluents emitted from diesel shed are passed through the Plant. The water thus collected is pollution free and is used for non-drinking purposes such as gardening and washing of the locomotives. 2.3 TECHNICAL INNOVATIONS Based on day-to-day maintenance problems a large number of innovations/modifications have been conceived and implemented in Diesel Shed, TKD during 2003-2004 which have improved the reliability and downtime of locomotives. Some of them are as below: 2.3.1 RTTM Test Stand Rear Truck Traction Motor Blower has been an area of concern due to a number of failures because of bearing seizure or belt breakage. A test stand has been developed in house by using available material for running the RTTM blower after assembly on load for a few hours so that both the bearing and the belts can be checked before the blower is fitted on the locomotive. A photograph of the test stand is reproduced below: 6|Page Figure 2-3: RTTM Test Stand 2.3.2 Test Stand for Opening Pressure of on Line lube oil Centrifuge: TKD shed has developed a “Test stand” for testing the opening pressure of the online lube oil centrifuge fitted in the Diesel Locomotive. This will ensure that online centrifuge does not open till adequate pressure is developed in system. This test stand shall also improve overall health of the system components such as main bearing, Connecting Rod, bearings, Camshafts, Valve lever mechanism, Piston & Liners etc. Figure 2-4: Test Stand for Opening Pressure of on Line lube oil Centrifuge 7|Page Figure 2-5: Closer look to test Stand for Opening Pressure of on Line lube oil Centrifuge 2.3.3 Expresser Crank Shaft Bearing Extractor Diesel Shed, TKD has fabricated one Expresser Crankshaft main ball bearing puller for extracting serviceable ball bearings in good conditions from the condemned C/Shaft as well as old unserviceable ball bearings from serviceable C/shaft without damaging any of the items. Prior to this, ball bearings were removed either by gas cutting or with the use of sledge hammers. Figure 2-6: Expresser Crank Shaft Bearing Extractor 8|Page 2.4 FUEL SECTION Figure 2-7: Fuel tank The section is concern with receiving, storage and refilling of diesel and lube oil. It has 3 large storage tanks and one underground tank for diesel storage which have a combined storage capacity of 10,60, 000 litres. This stock is enough to end for 15-16 days The fuel is supplied by truck from diesel mixing lab and after it IOC - Panipat refinery. Each truck diesel sample is treated in in unloaded. Sample check is necessary to avoid water, kerosene It also diesel. Two fuel filling points are established near the control room handles the Cardiam compound , lube oil. diesel is only for loco use if the diesel samples are not according to the standard , the delivery of the fuel is rejected. Viscosity of lube oil should be 100-1435 CST. Water mixing reduces the viscosity. Statement of diesel storage and received is made after every 10 days and the report is send to the Division headquarter. The record of each truck, wagons etc. are included in it. The record of issued oil is also sending to headquarter. After each 4 months. A survey is conducted by high level team about the storage, records etc. 0.1% of total stored fuel oil is given for handling losses by the HQ. The test reports of diesel includes the type of diesel (high speed diesel- Euro-3 with 0.035 % S), reason for test, inspection lot no, store tank no, batch no. etc. 9|Page 2.5 CONTROL ROOM It controls and regulates the complete movement, schedules, duty of each loco of the shed. Division level communications and contacts with each loco on the line are also handled by the control room. Full record of loco fleet, failures, duty, overdue and availability of locos are kept by the control room. It applies the outage target of loco for the shed, as decided by the HQ. It decides the locomotives mail and goods link that which loco will be deployed on which train. It operates 116 Mail and 11Goods link from the shed locos. For 0-0 outage total 127 loco should be on line. The schedule of duty, trains and link is decided by the control room according to the type of trains. If the loco does not return on scheduled time in the shed then the loco is termed as „overdue‟ and control room can use the loco of another shed if that is available. The lube oil consumption is also calculated by the control room for each loco:Lube Oil Consumption (LOC) = Lube oil consumed in litres/ total kms travelled ×100 New and better operational loco have less LOC. 10 | P a g e 2.6 CTA (Chief Technical Assistance) CELL This cell performs the following functions: Failure analysis of diesel locos Finding the causes of sub system failures and material failures Formation of inquiry panels of Mechanical and Electrical engineers and to help the special inquiry teams Material failures complains, warnings and replacement of stock communications with the component manufacturers Issues the preventive instructions to the technical workers and engineers Preparation of full detailed failure reports of each loco and sub systems, components after detailed analysis. The reports are then sent to the Divisional HQ. Correspondence with the headquarters is also done by the CTA Cell. The failures analysed are:Category 1 failures:- If the VIP trains loco fails or the train is delayed by the failure of another trains loco failure. Failure of the single loco may delay a no of trains. Non- reported failures:- the failure or delay of the local passenger trains for 2-3 hours is taken in this category. They are not reported to the higher levels and can be adjusted in the section operations. Foreign Railway-FR failures:- If the loco of one division fails in the other division and affects the traffic seriously in that division. The correspondence in this case is done by the cell. Other failures are:1. Material failure: - may be due to poor quality, defective material and defects in the manufacturing of the component. Component is replaced if fails frequently. 2. Maintenance failures: - if lapse is by the maintenance workers. Inquiry is done and punishment is set by CTA Cell on behalf of Sr. DME or instructions are issued for better maintenance. 11 | P a g e 3. Crew lapse: - proper actions are take or instructions issued to the crew of locos. After every 4 years IOH of loco is done in the shed. After 8years POH of loco is done at the Charbag loco shed –Lucknow. After 18 years rebuilding of loco is done at DMW-Patiala. Total life of a loco is 36 years. 12 | P a g e 2.7 TURBO SUPERCHARGER 2.7.1 INTRODUCTION The diesel engine produces mechanical energy by converting heat energy derived from burning of fuel inside the cylinder. For efficient burning of fuel, availability of sufficient air in proper ratio is a prerequisite. In a naturally aspirated engine, during the suction stroke, air is being sucked into the cylinder from the atmosphere. The volume of air thus drawn into the cylinder through restricted inlet valve passage, within a limited time would also be limited and at a pressure slightly less than the atmosphere. The availability of less quantity of air of low density inside the cylinder would limit the scope of burning of fuel. Hence mechanical power produced in the cylinder is also limited. An improvement in the naturally aspirated engines is the super-charged or pressure charged engines. During the suction stroke, pressurised stroke of high density is being charged into the cylinder through the open suction valve. Air of higher density containing more oxygen will make it possible to inject more fuel into the same size of cylinders and produce more power, by effectively burning it. A turbocharger, or turbo, is a gas compressor used for forced-induction of an internal combustion engine. Like a supercharger, the purpose of a turbocharger is to increase the density of air entering the engine to create more power. However, a turbocharger differs in that the compressor is powered by a turbine driven by the engine's own exhaust gases. 13 | P a g e 2.7.2 TURBO SUPERCHARGER AND ITS WORKING PRINCIPLE The exhaust gas discharge from all the cylinders accumulate in the common exhaust manifold at the end of which, turbo- supercharger is fitted. The gas under pressure there after enters the turbo- supercharger through the torpedo shaped bell mouth connector and then passes through the fixed nozzle ring. Then it is directed on the turbine blades at increased pressure and at the most suitable angle to achieve rotary motion of the turbine at maximum efficiency. After rotating the turbine, the exhaust gas goes out to the atmosphere through the exhaust chimney. The turbine has a centrifugal blower mounted at the other end of the same shaft and the rotation of the turbine drives the blower at the same speed. The blower connected to the atmosphere through a set of oil bath filters, sucks air from atmosphere, and delivers at higher velocity. The air then passes through the diffuser inside the turbo- supercharger, where the velocity is diffused to increase the pressure of air before it is delivered from the turbo- supercharger. Pressurising air increases its density, but due to compression heat develops. It causes expansion and reduces the density. This affects supply of high-density air to the engine. To take care of this, air is passed through a heat exchanger known as after cooler. The after cooler is a radiator, where cooling water of lower temperature is circulated through the tubes and around the tubes air passes. The heat in the air is thus transferred to the cooling water and air regains its lost density. From the after cooler air goes to a common inlet manifold connected to each cylinder head. In the suction stroke as soon as the inlet valve opens the booster air of higher pressure density rushes into the cylinder completing the process of super charging. The engine initially starts as naturally aspirated engine. With the increased quantity of fuel injection increases the exhaust gas pressure on the turbine. Thus the self-adjusting system maintains a proper air and fuel ratio under all speed and load conditions of the engine on its own. The maximum rotational speed of the turbine is 18000/22000 rpm for the Turbo supercharger and creates max. Of 1.8 kg/cm2 air pressure in air manifold of diesel engine, known as Booster Air Pressure (BAP). Low booster pressure causes black smoke due to incomplete combustion of fuel. High exhaust gas temperature due to after burning of fuel may result in considerable damage to the turbo supercharger and other component in the engine. 14 | P a g e 2.7.3 MAIN COMPONENTS OF TURBO-SUPERCHARGER Turbo- supercharger consists of following main components. Gas inlet casing. Turbine casing. Intermediate casing Blower casing with diffuser Rotor assembly with turbine and rotor on the same shaft. 2.7.4 ROTOR ASSEMBLY The rotor assembly consists of rotor shaft, rotor blades, thrust collar, impeller, inducer, centre studs, nosepiece, locknut etc. assembled together. The rotor blades are fitted into fir tree slots, and locked by tab lock washers. This is a dynamically balanced component, as this has a very high rotational speed. 15 | P a g e 2.7.5 LUBRICATING, COOLING AND AIR CUSHIONING 2.7.5.1 LUBRICATING SYSTEM One branch line from the lubricating system of the engine is connected to the turbosupercharger. Oil from the lube oils system circulated through the turbo- supercharger for lubrication of its bearings. After the lubrication is over, the oil returns back to the lube oil system, through a return pipe. Oil seals are provided on both the turbine and blower ends of the bearings to prevent oil leakage to the blower or the turbine housing. 2.7.5.2 COOLING SYSTEM The cooling system is integral to the water cooling system of the engine. Circulation of water takes place through the intermediate casing and the turbine casing, which are in contact with hot exhaust gases. The cooling water after being circulated through the turbo- supercharger returns back again to the cooling system of the locomotive. 2.7.5.3 AIR CUSHIONING There is an arrangement for air cushioning between the rotor disc and the intermediate casing face to reduce thrust load on the thrust face of the bearing which also solve the following purposes. It prevents hot gases from coming in contact with the lube oil. It prevents leakage of lube oil through oil seals. It cools the hot turbine disc. Pressurised air from the blower casing is taken through a pipe inserted in the turbo- supercharger to the space between the rotor disc and the intermediate casing. It serves the purpose as described above. 2.7.6 AFTER COOLER It is a simple radiator, which cools the air to increase its density. Scales formation on the tubes, both internally and externally, or choking of the tubes can reduce heat transfer capacity. This can also reduce the flow of air through it. This reduces the efficiency of the diesel engine. This is evident from black exhaust smoke emissions and a fall in booster pressure. 16 | P a g e 2.7.7 Fitments of higher capacity Turbo Supercharger- Following new generation Turbo Superchargers have been identified by diesel shed TKD for 2600/3100HP diesel engine and tabulated in table 1. Table 1: List of Turbo Superchargers TYPE 1.ALCO 2.ABB TPL61 3.HISPANO SUIZA HS 5800 NG 4. GE 7S1716 5. NAPIER NA-295 6. ABB VTC 304 POWER 2600HP 3100HP 3100HP 3100HP COOLING Water cooled Air cooled Air cooled Water cooled 2300,2600&3100HP Water cooled 2300,2600&3100HP Water cooled Figure 2-8: GE Turbocharger 17 | P a g e 2.7.8 TURBO RUN –DOWN TEST Turbo run-down test is a very common type of test done to check the free running time of turbo rotor. It indicates whether there is any abnormal sound in the turbo, seizer/ partial seizer of bearing, physical damages to the turbine, or any other abnormality inside it. The engine is started and warmed up to normal working conditions and running at fourth notch speed. Engine is then shut down through the over speed trip mechanism. When the rotation of the crank shaft stops, the free running time of the turbine is watched through the chimney and recorded by a stop watch. The time limit for free running is 90 to 180 seconds. Low or high turbo run down time are both considered to be harmful for the engine. 2.7.9 ROTOR BALANCING MACHINE A balancing machine is a measuring tool used for balancing rotating machine parts such as rotors of turbo supercharger, electric motors, fans, turbines etc. The machine usually consists of two rigid pedestals, with suspension and bearings on top. The unit under test is placed on the bearings and is rotated with a belt. As the part is rotated, the vibration in the suspension is detected with sensors and that information is used to determine the amount of unbalance in the part. Along with phase information, the machine can determine how much and where to add or remove weights to balance the part. 2.7.10 ADVANTAGES OF SUPER CHARGED ENGINES A super charged engine can produce 50 percent or more power than a naturally aspirated engine. The power to weight ratio in such a case is much more favorable. Better scavenging in the cylinders. This ensures carbon free cylinders and valves, and better health for the engine also. Better ignition due to higher temperature developed by higher compression in the cylinder. It increases breathing capacity of engine Better fuel efficiency due to complete combustion of fuel. 2.7.11 Defect in Turbochargers 1. Low Booster Air Pressure (BAP). 18 | P a g e 2. Oil throwing from Turbocharger because of seal damage or out of clearance. 3. Surging- Back Pressure due to uneven gap in Nozzle Ring or Diffuser Ring. 2.7.12 Must change components of Turbocharger. 1. Intermediate casing gasket. 2. Water outlet pipe flange gasket. 3. Water inlet pipe flange gasket. 4. Lube Oil inlet pipe rubber ‘o’ ring. 5. Turbine end Bearing. 6. Blower end Bearing. 7. Chimney gasket. 8. Rubber ‘o’ Ring kit. 9. Spring Washers. 10. Lock Washer Rotor Stud. 19 | P a g e 2.8 FUEL OIL SYSTEM Figure 2-9: Fuel Pump 2.8.1 INTRODUCTION All locomotive have individual fuel oil system. The fuel oil system is designed to introduce fuel oil into the engine cylinders at the correct time, at correct pressure, at correct quantity and correctly atomized. The system injects into the cylinder correctly metered amount of fuel in highly atomized form. High pressure of fuel is required to lift the nozzle valve and for better penetration of fuel into the combustion chamber. High pressure also helps in proper atomization so that the small droplets come in better contact with the compressed air in the combustion chamber, resulting in better combustion. Metering of fuel quantity is important because the locomotive engine is a variable speed and variable load engine with variable requirement of fuel. Time of fuel injection is also important for better combustion. 2.8.2 FUEL OIL SYSTEM The fuel oil system consists of two integrated systems. These are - 20 | P a g e FUEL INJECTION PUMP (F.I.P). FUEL INJECTION SYSTEM. 2.8.2.1 FUEL INJECTION PUMP Figure 2-10: Fuel Injection Pump It is a constant stroke plunger type pump with variable quantity of fuel delivery to suit the demands of the engine. The fuel cam controls the pumping stroke of the plunger. The length of the stroke of the plunger and the time of the stroke is dependent on the cam angle and cam profile, and the plunger spring controls the return stroke of the plunger. The plunger moves inside the barrel, which has very close tolerances with the plunger. When the plunger reaches to the BDC, spill ports in the barrel, which are connected to the fuel feed system, open up. Oil then fills up the empty space inside the barrel. At the correct time in the diesel cycle, the fuel cam pushes the plunger forward, and the moving plunger covers the spill ports. Thus, the oil trapped in the barrel is forced out through the delivery valve to be injected into the combustion chamber 21 | P a g e through the injection nozzle. The plunger has two identical helical grooves or helix cut at the top edge with the relief slot. At the bottom of the plunger, there is a lug to fit into the slot of the control sleeve. When the rotation of the engine moves the camshaft, the fuel cam moves the plunger to make the upward stroke. 22 | P a g e Figure 2-11: Cut out section of assembled FIP 23 | P a g e It may also rotate slightly, if necessary through the engine governor, control shaft, control rack, and control sleeve. This rotary movement of the plunger along with reciprocating stroke changes the position of the helical relief in respect to the spill port and oil, instead of being delivered through the pump outlet, escapes back to the low pressure feed system. The governor for engine speed control, on sensing the requirement of fuel, controls the rotary motion of the plunger, while it also has reciprocating pumping strokes. Thus, the alignment of helix relief with the spill ports will determine the effectiveness of the stroke. If the helix is constantly in alignment with the spill ports, it bypasses the entire amount of oil, and nothing is delivered by the pump. The engine stops because of no fuel injected, and this is known as „NO-FUEL‟ position. When alignment of helix relief with spill port is delayed, it results in a partly effective stroke and engine runs at low speed and power output is not the maximum. When the helix is not in alignment with the spill port throughout the stroke, this is known as „FULL FUEL POSITION‟, because the entire stroke is effective. Oil is then passed through the delivery valve, which is spring loaded. It opens at the oil pressure developed by the pump plunger. This helps in increasing the delivery pressure of oil. It functions as a non-return valve, retaining oil in the high pressure line. This also helps in snap termination of fuel injection, to arrest the tendency of dribbling during the fuel injection. The specially designed delivery valve opens up due to the pressure built up by the pumping stroke of plunger. When the oil pressure drops inside the barrel, the landing on the valve moves backward to increase the space available in the high-pressure line. Thus, the pressure inside the high-pressure line collapses, helping in snap termination of fuel injection. This reduces the chances of dribbling at the beginning or end of fuel injection through the fuel injection nozzles. 24 | P a g e 2.8.2.2 FUEL INJECTION NOZZLE Figure 2-12: Fuel Injection Nozzle The fuel injection nozzle or the fuel injector is fitted in the cylinder head with its tip projected inside the combustion chamber. It remains connected to the respective fuel injection pump with a steel tube known as fuel high pressure line. The fuel injection nozzle is of multi-hole needle valve type operating against spring tension. The needle valve closes the oil holes by blocking the oil holes due to spring pressure. Proper angle on the valve and the valve seat, and perfect bearing ensures proper closing of the valve. Due to the delivery stroke of the fuel injection pump, pressure of fuel oil in the fuel duct and the pressure chamber inside the nozzle increases. When the pressure of oil is higher than the valve spring pressure, valve moves away from its seat, which uncovers the small holes in the nozzle tip. High-pressure oil is then injected into the combustion chamber through these holes in a highly atomised form. Due to injection, hydraulic pressure drops, and the valve returns back to its seat terminating the fuel injection, termination of fuel injection may also be due to the bypassing of fuel injection through the helix in the fuel injection pump causing a sudden drop in pressure. 25 | P a g e 2.8.3 CALIBRATION OF FUEL INJECTION PUMPS Each fuel injection pump is subject to test and calibration after repair or overhaul to ensure that they deliver the same and stipulated amount of fuel at a particular rack position. Every pump must deliver regulated and equal quantity of fuel at the same time so that the engine output is optimum and at the same time running is smooth with minimum vibration. The calibration and testing of fuel pumps are done on a specially designed machine. The machine has a 5 HP reversible motor to drive a cam shaft through V belt. The blended test oil of recommended viscosity under controlled temperature is circulated through a pump at a specified pressure for feeding the pump under test. It is very much necessary to follow the laid down standard procedure of testing to obtain standard test results. The pump under test is fixed on top of the cam box and its rack set at a particular position to find out the quantum of fuel delivery at that position. The machine is then switched on and the cam starts making delivery strokes. A revolution counter attached to it is set to trip at 500 RPM or 100 RPM as required. With the cam making strokes, if the pump delivers any oil, it returns back to the reservoir in normal state. A manually operated solenoid switch is switched on and the oil is diverted to a measure glass till 300 strokes are completed after operation of the solenoid switch. Thus the oil discharged at 300 working strokes of the pump is measured which should normally be within the stipulated limit. The purpose of measuring the output in 300 strokes is to take an average to avoid errors. The pump is tested at idling and full fuel positions to make sure that they deliver the correct amount of fuel for maintaining the idling speed and so also deliver full HP at full load. A counter check of the result at idling is done on the reverse position of the motor which simulates slow running of the engine. If the test results are not within the stipulated limits as indicated by the makers then adjustment of the fuel rack position may be required by moving the rack pointer, by addition or removal of shims behind it. The thickness of shims used should be punched on the pump body. The adjustment of rack is done at the full fuel position to ensure that the engine would deliver full horse power. Once the adjustment is done at full fuel position other adjustment should come automatically. In the event of inconsistency in results between full fuel and idling fuel, it may call for change of plunger and barrel assembly. 26 | P a g e The calibration value of fuel injection pump as supplied by the makers is tabulated in table 2 at 300 working strokes, rpm -500, temp.-100 to 120 0F & pressure 40 PSI: Table 2: Calibration Value of different FIPs Dia. of element(mm) 15 mm Rack(mm) 30 mm(full load) 9 mm(Idling) 28 mm (full load) 9 mm (Idling) Required volume fuel(cc) 351 cc +5/-10 34 cc +1/-5 401 cc +4/-11 45 cc +1/-5 of 17 mm Errors are likely to develop on the calibration machine in course of time and it is necessary to check the machine at times with master pumps supplied by the makers. These pumps are perfectly calibrated and meant for use as reference to test the calibration machine itself. Two master pumps, one for full fuel and the other for idling fuel are there and they have to be very carefully preserved only for the said purpose. 2.8.4 FUEL INJECTION NOZZLE TEST The criteria of a good nozzle are good atomization, correct spray pattern and no leakage or dribbling. Before a nozzle is put to test the assembly must be rinsed in fuel oil, nozzle holes cleaned with wire brush and spray holes cleaned with steel wire of correct thickness. The fuel injection nozzles are tested on a specially designed test stand, where the following tests are conducted. 2.8.4.1 SPRAY PATTERN Spray of fuel should take place through all the holes uniformly and properly atomized. While the atomization can be seen through the glass jar, an impression taken on a sheet of blotting paper at a distance of 1 to 1 1/2 inch also gives a clear impression of the spray pattern. 2.8.4.2 SPRAY PRESSURE The stipulated correct pressure at which the spray should take place is 3900-4050 psi for new and 3700-3800 psi for reconditioned nozzles. If the pressure is down to 3600 psi the nozzle needs replacement. The spray pressure is indicated in the gauge provided in the test machine. Shims 27 | P a g e are being used to increase or decrease the tension of nozzle spring which increases or decreases the spray pressure. 2.8.4.3 DRIBBLING There should be no loose drops of fuel coming out of the nozzle before or after the injections. In fact the nozzle tip of a good nozzle should always remain dry. The process of checking dribbling during testing is by having injections manually done couple of times quickly and checks the nozzle tip whether leaky. Raising the pressure within 100 psi of set injection pressure and holding it for about 10 seconds may also give a clear idea of the leakage. The reasons of nozzle dribbling are (1) Improper pressure setting (2) Dirt stuck up between the valve and the valve seat (3) Improper contact between the valve and valve seat (4) Valve sticking inside the valve body. 2.8.4.4 NOZZLE CHATTER The chattering sound is a sort of cracking noise created due to free movement of the nozzle valve inside the valve body. If it is not proper then chances are that the valve is not moving freely inside the nozzle. 28 | P a g e 2.9 BOGIE Figure 2-13: Diesel Engine Bogie 2.9.1 INTRODUCTION A 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. Bogies serve a number of purposes: To support the rail vehicle body To run stably on both straight and curved track To ensure ride comfort by absorbing vibration, and minimizing centrifugal forces when the train runs on curves at high speed. To minimize generation of track irregularities and rail abrasion. Usually two bogies are fitted to each carriage, wagon or locomotive, one at each end. 29 | P a g e 2.9.2 Key Components Of a Bogie The bogie frame itself. Suspension to absorb shocks between the bogie frame and the rail vehicle body. Common types are coil springs, or rubber airbags. At least two wheel set, composed of axle with a bearings and wheel at each end. Axle box suspension to absorb shocks between the axle bearings and the bogie frame. The axle box suspension usually consists of a spring between the bogie frame and axle bearings to permit up and down movement, and sliders to prevent lateral movement. A more modern design uses solid rubber springs. Brake equipment:-Brake shoes are used that are pressed against the tread of the wheels. Traction motors for transmission on each axle. 2.9.3 CLASSIFICATION OF BOGIE Bogie is classified into the various types described below according to their configuration in terms of the number of axle, and the design and structure of the suspension. According to UIC classification two types of bogie in Indian Railway are: Bo-Bo Co-Co Figure 2-14: Bo-Bo and Co-Co Bogies 30 | P a g e A Bo-Bo is a locomotive with two independent four-wheeled bogies with all axles powered by individual traction motors. Bo-Bo is mostly suited for express passenger or medium-sized locomotives. Co-Co is a code for a locomotive wheel arrangement with two six-wheeled bogies with all axles powered, with a separate motor per axle. Co-Co is most suited to freight work as the extra wheels give them good adhesion. They are also popular because the greater number of axles results in a lower axle load to the track. 2.9.4 Failure and remedies in the bogie section: Breakage of coiled springs due to heavy shocks or more weight or defective material. They are tested time to time to check the compression limit. Broken springs are replaced. 14 to 60 thou clearance is maintained between the axle and suspension bearing. Lateral clearance is maintained between 60 and 312 thou. Less clearance will burn the oil and will cause the seizure of axle. Condemned parts are replaced. RDP tests are done on the frame parts, welded parts, corners, guide links and rigid structures of bogie and minor cracks can be repaired by welding. Axle suspension bearings may seizure due to oil leakage, cracks etc. If axle box bearing’s roller is damaged then replaced it completely. 31 | P a g e 2.10 EXPRESSOR Figure 2-15: Expressor 2.10.1 INTRODUCTION In Indian Railways, the trains normally work on vacuum brakes and the diesel locos on air brakes. As such provision has been made on every diesel loco for both vacuum and compressed air for operation of the system as a combination brake system for simultaneous application on locomotive and train. 32 | P a g e In ALCO locos the exhauster and the compressor are combined into one unit and it is known as EXPRESSOR. It creates 23" of vacuum in the train pipe and 140 PSI air pressure in the reservoir for operating the brake system and use in the control system etc. The expressor is located at the free end of the engine block and driven through the extension shaft attached to the engine crank shaft. The two are coupled together by fast coupling (Kopper's coupling). Naturally the expressor crank shaft has eight speeds like the engine crank shaft. There are two types of expressor are, 6CD, 4UC & 6CD, 3UC. In 6CD, 4UC expressor there are six cylinder and four exhauster whereas 6CD, 3UC contain six cylinder and three exhauster. 2.10.2 WORKING OF EXHAUSTER Air from vacuum train pipe is drawn into the exhauster cylinders through the open inlet valves in the cylinder heads during its suction stroke. Each of the exhauster cylinders has one or two inlet valves and two discharge valves in the cylinder head. A study of the inlet and discharge valves as given in a separate diagram would indicate that individual components like (1) plate valve outer (2) plate valve inner (3) spring outer (4) spring inner etc. are all interchangeable parts. Only basic difference is that they are arranged in the reverse manner in the valve assemblies which may also have different size and shape. The retainer stud in both the assemblies must project upward to avoid hitting the piston. The pressure differential between the available pressure in the vacuum train pipe and inside the exhauster cylinder opens the inlet valve and air is drawn into the cylinder from train pipe during suction stroke. In the next stroke of the piston the air is compressed and forced out through the discharge valve while the inlet valve remains closed. The differential air pressure also automatically opens or closes the discharge valves, the same way as the inlet valves operate. This process of suction of air from the train pipe continues to create required amount of vacuum and discharge the same air to atmosphere. The VA-1 control valve helps in maintaining the vacuum to requisite level despite continued working of the exhauster. 2.10.3 Compressor The compressor is a two stage compressor with one low pressure cylinder and one high pressure cylinder. During the first stage of compression it is done in the low pressure cylinder where suction is through a wire mesh filter. After compression in the LP cylinder air is 33 | P a g e delivered into the discharge manifold at a pressure of 30 / 35 PSI. Workings of the inlet and exhaust valves are similar to that of exhauster which automatically open or close under differential air pressure. For inter-cooling air is then passed through a radiator known as intercooler. This is an air to air cooler where compressed air passes through the element tubes and cool atmospheric air is blown on the outside fins by a fan fitted on the expressor crank shaft. Cooling of air at this stage increases the volumetric efficiency of air before it enters the highpressure cylinder. A safety valve known as inter cooler safety valve set at 60 PSI is provided after the inter cooler as a protection against high pressure developing in the after cooler due to defect of valves. After the first stage of compression and after-cooling the air is again compressed in a cylinder of smaller diameter to increase the pressure to 135-140 PSI in the same way. This is the second stage of compression in the HP cylinder. Air again needs cooling before it is finally sent to the air reservoir and this is done while the air passes through a set of coiled tubes after cooler. 34 | P a g e Figure 2-16: Schematic Diagram of Expressor 35 | P a g e 2.11 SPEEDOMETER Figure 2-17: Speedometer and other gauges 2.11.1 INTRODUCTION The electronic speedometer is intended to measure traveling speed and to record the status of selected locomotive engine parameters every second. It comprises a central processing unit that performs the basic functions, two monitors that are used for displaying the measured speed values and entering locomotive driver‟s identification data and drive parameters and a speed transducer. The speedometer can be fitted into any of railway traction vehicles. The monitor is mounted on every driver‟s place in a locomotive. It is connected to the CPU by a serial link. Monitor transmits a driver, locomotive and train identifications data to the CPU and receives data on travel speed, partial distance traveled, real time and speedometer status from the CPU A locomotive driver communicates with the speedometer using the monitor: a keyboard and alphanumeric displays are used for authorization purposes, travel speed values are monitored on analog and digital displays, whereas alphanumeric displays, LEDs and a buzzer signal provide information on speedometer and vehicle status. 2.11.2 WORKING MECHANISM Speedometer is a closed loop system in which opto-electronic pulse generator is used to convert the speed of locomotive wheel into the corresponding pulses. Pulses thus generated are then converted into the corresponding steps for stepper motor. These steps then decide the movement 36 | P a g e of stepper motor which rotates the pointer up to the desired position. A feedback potentiometer is also used with pointer that provides a signal corresponding to actual position of the pointer, which then compared with the step of stepper motor by measuring and control section. If any error is observed, it corrected by moving the pointer to corresponding position. Presently a new version of speed-time-distance recorder cum indicator unit TELPRO is used in the most of the locomotive. Features and other technical specification of this speedometer are given below. Figure 2-18: Block Diagram for speedometer Pulse 2.11.3 Salient features Light weight and compact in size Adequate journey data recording capacity Both analog and digital displays for speed Both internal and external memories for data storage Memory freeze facility Step less wheel wear compensation Dual sensor opto electronic pulse generator for speed sensing Over speed audio visual alarm 7-digit odometer User friendly Windows-based data extraction and analysis software 37 | P a g e Graphical and tabular reports generation for easy analyzing of recorded data Cumulative, Trip-wise, Train-wise, Driver-wise and Date-wise report generation Master-Slave configuration 2.11.4 Applications Speed indication for driver. Administrative control of traction vehicle for traffic scheduling. Vehicle trend analysis in case of derailment/accident. Analysis of driver’s operational performance to provide training, if required. Figure 2-19: Telpro Speedometer Circuit 2.11.5 Technical Specifications The system requires a wide operating voltage of 50 V DC to 140 V DC. 38 | P a g e Table 3: Operating conditions Conditions Temperature Relative humidity Accuracy of Master & Slave Table 4: Analogue indication Values -5°C to +70°C 95% (max) ±1.0% of full scale deflection Factors Scale spread over Illumination Brightness control Dial size Dial colour Max speed range Values 240° 12 equally spaced LEDs on dial circumference 0-100% in 10 steps 120 mm White with black pointer & numerals 0-150, 0-160 & 0-180 Kmph (can be made as per customer‟s request) Table 5: Digital indication Features LCD display Time display Table 6: General Values 16x2 character alphanumeric LCD with backlit control HH:MM:SS on 24-hour scale Factors Size Odometer Input speed sensing Values 145x215x160 mm (typical) 7 digit with 1km resolution 2 inputs for opto-electronic pulse generator 200 or 100 pulses/rev (configurable) Weight: Master & Slave (approx) 3.5 kg (Master); 3.15 kg (Slave) 39 | P a g e 2.12 CYLINDER HEAD Figure 2-20: Cylinder Head 2.12.1 INTRODUCTION The cylinder head is held on to the cylinder liner by seven hold down studs or bolts provided on the cylinder block. It is subjected to high shock stress and combustion temperature at the lower face, which forms a part of combustion chamber. It is a complicated casting where cooling passages are cored for holding water for cooling the cylinder head. In addition to this provision is made for providing passage of inlet air and exhaust gas. Further, space has been provided for holding fuel injection nozzles, valve guides and valve seat inserts also. 2.12.2 Components of cylinder head In cylinder heads valve seat inserts with lock rings are used as replaceable wearing part. The inserts are made of stellite or weltite. To provide interference fit, inserts are frozen in ice and cylinder head is heated to bring about a temperature differential of 250F and the insert is pushed into recess in cylinder head. The valve seat inserts are ground to an angle of 44.5 whereas the valve is ground to 45 to ensure line contact. (In the latest engines the inlet valves are ground at 30° and seats are ground at 29.5°). Each cylinder has 2 exhaust and 2 inlet valves of 2.85" in dia. The valves have stem of alloy steel and valve head of austenitic stainless steel, butt-welded together into a composite unit. The valve head material being austenitic steel has high level of stretch resistance and is capable of hardening above Rockwell- 34 to resist deformation due to continuous pounding action. 40 | P a g e The valve guides are interference fit to the cylinder head with an interference of 0.0008" to 0.0018". After attention to the cylinder heads the same is hydraulically tested at 70 psi and 190F. The fitment of cylinder heads is done in ALCO engines with a torque value of 550 Ft. lbs. The cylinder head is a metal-to-metal joint on to cylinder. ALCO 251+ cylinder heads are the latest generation cylinder heads, used in updated engines, with the following feature: Fire deck thickness reduced for better heat transmission. Middle deck modified by increasing number of ribs (supports) to increase its mechanical strength. The flying buttress fashion of middle deck improves the flow pattern of water eliminating water stagnation at the corners inside cylinder head. Water holding capacity increased by increasing number of cores (14 instead of 11) Use of frost core plugs instead of threaded plugs, arrest tendency of leakage. Made lighter by 8 kgs (Al spacer is used to make good the gap between rubber grommet and cylinder head.) Retaining rings of valve seat inserts eliminated. 2.12.3 Benefits: Better heat dissipation Failure reduced by reducing crack and eliminating sagging effect of fire deck area. 41 | P a g e 2.13 Maintenance and Inspection Figure 2-21: Inspection of an engine 2.13.1 Cleaning: By dipping in a tank containing caustic solution or ORION-355 solution with water (1:5) supported by air agitation and heating. 2.13.2 Crack Inspection: Check face cracks and inserts cracks by dye penetration test. 2.13.3 Hydraulic Test: Conduct hyd. test (at 70 psi, 200°F for 30 min.) for checking water leakage at nozzle sleeve, ferrule, core plugs and combustion face. 2.13.4 Dimensional check : Face seat thickness: within 0.005" to 0.020" 2.13.5 Straightness of valve stem: Run out should not exceed 0.0005" Free & Compressed height (at 118 lbs.) of springs: 3 13/16" & 4 13/16" 42 | P a g e 2.13.6 Checks during overhauling: Ground the valve seat insert to 44.5°/29.5°, maintain run out of insert within 0.002" with respect to valve guide while grinding. Grind the valves to 45°/30° and ensure continuous hair line contact with valve guide by checking colour match. Ensure no crack has developed to inserts after grinding, checked by dye penetration test. Make pairing of springs and check proper draw on valve locks and proper condition of groove and locks while assembling of valves. Lap the face joint to ensure leak proof joint with liner. 2.13.7 Blow by test: On bench blow by test is conducted to ensure the sealing effect of cylinder head. Blow by test is also conducted to check the sealing efficiency of the combustion chamber on a running engine, as per the following procedure: Run the engine to attain normal operating temperature (65°C) Stop running after attaining normal operating temperature. Bring the piston of the corresponding cylinder at TDC in compression stroke. Fit blow-by gadget (Consists of compressed air line with the provision of a pressure gauge and stopcock) removing decompression plug. Charge the combustion chamber with compressed air. Cut off air supply at 70 psi. Through stop cock and record the time when it comes down to zero.7 to 10 secs is OK. 43 | P a g e 2.14 PIT WHEEL LATHE Figure 2-22: Pit Wheel Lathe Machine 2.14.1 INTRODUCTION Various type of wear may occur on wheal tread and flange due to wheel skidding and emergency breaking. Four type of wear may occur as follows: Tread wear Root wear Skid wear and Flange wear For maintaining the required profile pit wheel lathe are used. This lathe is installed in the pit so that wheel turning is without disassembling the axle and lifting the loco and hence the name “pit wheel lathe” 2.14.2 Wheel turning Wheel turning on this lathe is done by rotating the wheels, both wheels of an axle are placed on the four rollers, two for each wheel. Rollers rotate the wheel and a fixed turning tool is used for turning the wheel. Different gages are used in this section to check the tread profile. Name of these gages are: Star gage Root wear gage 44 | P a g e Flange wear gage J gage j-gage is used to calculate the app. Dia of wheel. Dia. Of wheel = 962 + 2 × (j-gage reading) mm Figure 2-23: Wheel Specifications 2.14.3 CAUSES OF WHEEL SKIDDING On excessive brake cylinder pressure (more than 2.5 kg/cm²). Using dynamic braking at higher speeds. When at the time of application of dynamic braking, the brakes of loco would have already been applied (in case of failure of D-1 Pilot valve). Continue working, when C-3-W Distributor valve P/G handle is in wrong position. Due to shunting of coaches with loco without connecting their B.P./vacuum pipe. Shunting at higher speeds. Continue working when any of the brake cylinders of loco has gotten jammed. 45 | P a g e The time of application/release of brakes of any of the brake cylinder being larger than the others. When any of the axles gets locked during on the line. 46 | P a g e 2.15 FAILURE ANALYSIS Figure 2-24: A Failure Detection Device 2.15.1 INTRODUCTION A part or assembly is said to have failed under one of the three conditions:1. When it becomes completely inoperable-occurs when the component breaks into two or more pieces. When it is still inoperable but is no longer able to perform its intended function satisfactorily- due to wearing and minor damages. 2. When serious deterioration has made it unreliable or unsafe for continuous use, thus necessitating its complete removal from service for repair or replacement-due to presence of cracks such as thermal cracks, fatigue crack, hydrogen flaking. In this section we will study about: Metallurgical lab. Ultrasonic test 47 | P a g e Zyglo test and RDP test. 2.15.2 Metallurgical lab. Metallurgical lab concerns with the study of material composition and its properties. Specimens are checked for its desired composition. In this section various tests are conducted like hardness test, composition test e.g determination of percentage of carbon, swelling test etc. Table 7: Functions of some Alloying Materials S. No. 1. 2. 3. 4. 5. 6. 7. Compound Phosphorous Graphite Cementite Chromium Nickel Nitride rubber Neoprene Function Increase the fluidity property Increase machinability Increase hardness Used for corrosion prevention Used for heat resistance Oil resistance in touch of „O‟ ring Air resistance & oil resistance in fast coupling in rubber block. 8. Silicon Heat resistance and wear resistance (up to 600 ºC) use at top and bottom pore of liner. 2.15.3 Swelling test Swelling test is performed for rubber in this test percentage increase in weight of the rubber after immersing in solution is measured and increase in weight should not be more than 20%. Two type of swelling test viz low swelling and high swelling are performed in the lab. Three type of oil solution are used for this purpose listed below:- 48 | P a g e ASTM 1 ASTM 2 ASTM 3 2.15.4 Procedure 1. Select specimen for swelling test. 2. Note the weight of the specimen. 3. Put in the vessel containing ASTM 1 or ASTM 3. 4. Put the oven at 100 ºC. 5. Put the vessel in the oven for 72 hrs. 6. After 72 hrs. Weigh the specimen. 2.15.5 Rubber Broadly there are two types of rubber: 1. Natural rubber- this has very limited applications. It is used in windows and has a life of 1 year. 2. Synthetic rubber- this is further subdivided into five types. VUNA-N (2 year life) Polychloroprene or Neoprene (2 year life) SBR (3 year life) Betel (3 year life) Silicone (3 year life). VUNA-N rubber is used in oily or watery area; neoprene is used in areas surrounded by oil and air while betel and silicone are used in areas subjected to high temperatures such as in pistons. When the fresh supply of rubber comes from the suppliers it is tested to know its type. The test consists of two solutions, solution 1 and solution 2, which are subjected to the vapors of the rubber under test and then the color change in solution is used for determination of the type of rubber. The various color changes are as follows: 49 | P a g e Violet- natural rubber Pink- nitrile Green-SBR When no color change is observed the vapours are passed through solution 2. The colour change in solution 2 is: Pink- neoprene. Silicone produces white powder on burning. If there is no result on burning then the rubber is surely betel. 2.15.6 ULTRASONIC TESTING In ultrasonic testing, very short ultrasonic pulse-waves with center frequencies ranging from 0.115 MHz and occasionally up to 50 MHz are launched into materials to detect internal flaws or to characterize materials. Ultrasonic testing is often performed on steel and other metals and alloys, though it can also be used on concrete, wood and composites, albeit with less resolution. It is a form of nondestructive testing. 2.15.7 ZYGLO TEST The zyglo test is a nondestructive testing (NTD) method that helps to locate and identify surface defects in order to screen out potential failure-producing defects. It is quick and accurate process for locating surface flaws such as shrinkage cracks, porosity, cold shuts, fatigue cracks, grinding cracks etc. The ZYGLO test works effectively in a variety of porous and non-porous materials: aluminum, magnesium, brass, copper, titanium, bronze, stainless steel, sintered carbide, nonmagnetic alloys, ceramics, plastic and glass. Various steps of this test are given below: Step 1 – pre-clean parts. Step 2 – apply penetrant Step 3 – remove penetrant Step 4 – dry parts Step 5 – apply developer Step 6 – inspection 50 | P a g e 2.15.8 RED DYE PENETRATION TEST (RDP) Dye penetrant inspection (DPI), also called liquid penetrant inspection (LPI), is a widely applied and low-cost inspection method used to locate surface-breaking defects in all non-porous materials (metals, plastics, or ceramics). Penetrant may be applied to all non-ferrous materials, but for inspection of ferrous components magnetic particle inspection is preferred for its subsurface detection capability. LPI is used to detect casting and forging defects, cracks, and leaks in new products, and fatigue cracks on in-service components. 2.15.8.1 Principles DPI is based upon capillary action, where low surface tension fluid penetrates into clean and dry surface-breaking discontinuities. Penetrant may be applied to the test component by dipping, spraying, or brushing. After adequate penetration time has been allowed, the excess penetrant is removed, a developer is applied. The developer helps to draw penetrant out of the flaw where a visible indication becomes visible to the inspector. 51 | P a g e 2.16 SCHEDULED EXAMINATION Figure 2-25: A Crankshaft taken out for Scheduled Examination 2.16.1 INTRODUCTION The railway traffic requires safety and reliability of service of all railway vehicles. Suitable technical systems and working methods adapted to it, which meet the requirements on safety and good order of traffic should be maintained. For detection of defects, non-destructive testing methods - which should be quick, reliable and cost-effective - are most often used. Inspection of characteristic parts is carried out periodically in accordance with internal standards or regulations; inspections may be both regular and extraordinary; the latter should be carried out after collisions, derailment or grazing of railway vehicles. Maintenance of railway vehicles is scheduled in accordance with periodic inspections and regular repairs. Inspections and repairs are prescribed according to the criteria of operational life, limited by the time of operation of a locomotive in traffic or according to the criteria of operational life including the path traveled. 52 | P a g e For the proper functioning of diesel shed and to reduce the number of failures of diesel locos, there is a fixed plan for every loco, at the end of which the loco is checked and repaired. This process is called scheduling. There are two types of schedules which are as follows: Major schedules Minor schedule 2.16.2 MINOR SCHEDULES Schedule is done by the technicians when the loco enters the shed. After 15 days there is a minor schedule. The following steps are done every minor schedule & known as SUPER CHECKING. The lube oil level & pressure in the sump is checked. The coolant water level & pressure in the reservoir is checked. The joints of pipes & fittings are checked for leakage. Check super charger, compressor & its working. The engine is checked thoroughly for the abnormal sounds if there is any. F.I.P. is checked properly by adjusting different rack movements. This process should be done nearly four hour only. After this the engine is sent in the mail/goods running repairs for repairs. There are following types of minor schedules: T-1 SHEDULE AFTER 15 DAYS T-2 SHEDULE AFTER 30 DAYS T-1 SHEDULE AFTER 45 DAYS M-2 SHEDULE AFTER 60 DAYS T-1 SHEDULE AFTER 75 DAYS T-2 SHEDULE AFTER 90 DAYS T-1 SHEDULE AFTER 105 DAYS 2.16.2.1 TRIP-1 Fuel oil & lube check. Expressor discharge valve. 53 | P a g e Flexible coupling’s bubbles. Turbo run down test. Record condition of wheels by star gauge. Record oil level in the axle caps for suspension bearing. 2.16.2.2 TRIP-2 All the valves of the expressor are checked. Primary and secondary fuel oil filters are checked. Turbo super charger is checked. Under frame are checked. Lube oil of under frame checked. 2.16.2.3 MONTHLY-2 SEHEDULE All the works done in T-2 schedule. All cylinder head valve loch check. Sump examination. Main bearing temperature checked. Expressor valve checked. Wick pad changed. Lube oil filter changed. Strainer cleaned. Expressor oil changed. 2.16.3 MAJOR SCHEDULES These schedules include M-4, M-8 M-12 and M-24. The M-4 schedule is carried out for 4 months and repeated after 20 months. The M-8 schedule is carried out for 8 months and repeated after 16 months. The M-12 is an annual schedule whereas the M-24 is two years. Besides all of these schedules for the works that are not handled by the schedules there is an out of course section, which performs woks that are found in inspection and are necessary. As any Locomotive arrives in the running section first of all the driver diary is checked which contains information about the locomotive parameters and problem faced during operation. The 54 | P a g e parameters are Booster air pressure (BAP), Fuel oil pressure (FOP), Lubricating oil pressure (LOP) and Lubricating oil consumption (LOC). After getting an idea of the initial problems from the driver‟s diary the T-1 schedule is made for inspection and minor repairs. 2.16.3.1 M-4 Schedule 1. Run engine; check operation of air system safety valves and expressor crankcase lube oil pressure. 2. Stop engine; carry out dry run operational test, check FIP timing and uniformity of rack setting and correct if necessary. 3. Engine cylinder head:-Tighten all air and exhaust elbow bolts, check valve clearance, exhaust manifold elbow etc. 4. Engine crankcase cover:-Remove crankcase cover and check for any foreign material. Renew gaskets. 5. Clean Strainer and filters, replace paper elements. 6. Compressed air and vacuum system:-Check, clean and recondition rings, piston, Intake strainers, and inlet and exhaust valve, lube oil relief valve, unloading valve. Drain, clean and refill crankcase. 7. Radiator fan- tightens bolts and top up oil if necessary. 8. Roller bearing axle boxes. Check for loose bolts, loss of grease, sign of overheating. Remove covers, clean and examine roller races and cages for defects. Carry out ultrasonic test of axles. 9. Clean cyclonic filters, bag filters and check the condition of rubber bellows of air intake system. 10. Renew airflow indicator valve. 11. Carry out blow bye test and gauge wheel wears. 55 | P a g e 2.17 YEARLY/MECHANICAL Figure 2-26: Engine block taken out for yearly maintanence In this section, major schedules such as M-24, M48 and M-72 are carried out. Here, complete overhauling of the locomotives is done and all the parts are sent to the respective section and new parts are installed after which load test is done to check proper working of the parts. The work done in these sections are as follows: 56 | P a g e 1) Repeating of all items of trip, quarterly and monthly schedule. 2) Testing of all valves of vacuum/compressed air system. Repair if necessary. 3) Replacement of coalesce element of air dryer. 4) Reconditioning, calibration and checking of timing of FIP is done. Injector is overhauled. 5) Cleaning of Bull gear and overhauling of gear-case is done. 6) RDP testing of radiator fan, greasing of bearing, checking of shaft and keyway. Examination of coupling and backlash checking of gear unit is done. 7) Checking of push rod and rocker arm assembly. Replacement is done if bent or broken. Checking of clearance of inlet and exhaust valve is also done. 8) Examination of piston for cracks, renew bearing shell of connecting rod fitment. Checking of connecting rod elongation is done. 9) Checking of crankshaft thrust and deflection. Shims are added if deflection is more than the tolerance limit. 10) Main bearing is discarded if it has embedded dust, or gives evidence of fatigue failure or has worn. 11) Checking of cracks in water header and elbow. Install new gaskets in the air intake manifold. Overhauling of exhaust manifold is done. 12) Checking of cracks in crankcase, lube oil header, jumper and tube leakage in lube oil cooler. Replace or dummy of tubes is done. 13) Lube oil system- Overhauling of pressure regulating valves, by pass valve, lube oil filters and strainers is done. 14) Fuel oil system- Overhauling of pressure regulating valve, pressure relief valve, primary and secondary filters. 15) Checking of rack setting, governor to rack linkage, fuel oil high-pressure line is done. 16) Cooling water system- draining of the cooling water from system and cleaning with new water carrying 4 kg tri-phosphate is done. All water system gaskets are replaced. Water drain cock is sealed. Copper vent pipes are changed and water hoses are renewed. 17) Complete overhauling of water pump is done. Checking of impeller shaft for wear and lubrication of ball bearing. Water and oil seal renewal. 57 | P a g e 18) Complete overhauling of expressor/compressor, pistons rings and oil seal renewed. Expressor orifice test is carried out. 19) Complete overhauling of Turbo supercharger is done. Dynamic balancing and Zyglo test of the turbine/impeller is done. Also, hydraulic test of complete Turbo supercharger is done. 20) Overhauling of after-cooler is done. Telltale hole is checked for water leak. 21) Inspection of the crankcase cover gasket and diaphragm is done. It is renewed if necessary. 22) Rear T/Motor blower bearing are checked and changed. Greasing of bearing is done. 23) Cyclonic filter rubber bellows and rubber hoses are changed. Air intake filter and vacuum oil bath filter are cleaned and oiled. 24) Radiators are reconditioned; fins are straightened by hydraulic test to detect leakage and cleaning by approved chemical. 25) Bogie- Checking of frame links, spring, equalizing beam locating roller pins for free movement, buffer height, equalizer beam for cracks, rail guard distance is done. Refilling of center plate and loading pads is done. Journal bearings are reconditioned. 26) Axle box- cleaning of axle box housing is done. 27) Wheels- inspection for fracture or flat spot. Wheel are turned and gauged. 28) Checking of wear on horn cheek liners and T/M snubber wear plates. 29) Checking of brake parts for wear, lubrication of slack adjusters is done. Inspection for fatigue, crack and distortion of center buffers couplers, side buffers are done. 30) Traction motor suspension bearing- cleaning of wick assembly, checking of wear in motor nose suspension. Correct fitment of felt wick lubricators is ensured. Axle boxes are refilled with fresh oil. Testing of all pressure vessels is carried out. 2.17.1 Examination while Engine is running. 31) Expressor orifice test is performed. Engine over speed trip assembly operation, LWS operation are checked. Checking of following items is done: Water and oil leakage at telltale hole of water pump, turbo return pipes for leakage and crack, air system for leakage, fuel pump and pipes for leakage, exhaust manifold for 58 | P a g e leaks, engine lube oil pressure at idle, turbo for smooth run down as engine is stopped. Difference in vacuum between vacuum reservoir pipe and expressor crankcase & and pressure difference across lube oil filters at idle and full engine speed are recorded. 32) Brakes at all application positions are checked. Checking of fast and flexible coupling is done and the expressor is properly aligned. Inspection of camshaft, lubrication of hand brake lever and chain. 33) Speedometer- Overhaul, testing of speed recorder and indicator, pulse generator is done. 2.17.2 (38). Additional items for WDP1:Overhauling and operation of TBU is done, center pivot pin is checked, and CPP bush housing liners are checked for wear, inspection of vibration dampers for oil leakage and their operation. RDP test is done to check for cracks at critical location in the bogie frame. Checking of coil springs for free height. 2.17.3 (39). Additional items for WDP2 locos:Check for cracks in bogie frame and bolster. Checking of hydraulic dampers for oil leakage. Check coil spring for free height. Zyglo test of guide link bolts is performed. Examination of taper roller bearing for their condition and clearance is done. Check and change center pivot liners. Checking of tightness of nuts on brake head pin. Disassembly, cleaning, greasing, repairing, replacement of brake cylinder parts is done. Ultrasonic test of axles is performed. Visual Examination of suspension springs for crack and breakage. Checking of free and working height of spring. Inspection of bull gear for any visible damage is done and the teeth profile is checked. Test loco on load box as per RDSO standards. 59 | P a g e 3 Project Work To do analysis of main bearing seizures loco type-wise/make wise during the past 5 years leading to damage of crankshaft/engine block and to study cause of main bearing seizure and suggest remedies to overcome fail of main bearing/cs/engine block. The main bearings are the bearings in which the crankshaft rotates. Hence, for an engine to work properly it should have very good main bearings. Moreover, better is the quality of main bearing, lesser the frictional force encountered by the crankshaft while rotating, which results in lesser energy being wasted to overcome the frictional resistance and thereby resulting in improved overall engine efficiency. 60 | P a g e 3.1 Introduction to bearing Figure 3-1: Introduction to Bearings A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can handle. There are at least six common principles of operation: plain bearing, also known by the specific styles: bushings, journal bearings, sleeve bearings, rifle bearings rolling-element bearings such as ball bearings and roller bearings jewel bearings, in which the load is carried by rolling the axle slightly off-centre fluid bearings, in which the load is carried by a gas or liquid magnetic bearings, in which the load is carried by a magnetic field flexure bearings, in which the motion is supported by a load element which bends Common motions permitted by bearings are: Axial rotation e.g. shaft rotation Linear motion e.g. drawer spherical rotation e.g. ball and socket joint 61 | P a g e hinge motion e.g. door, elbow, knee Figure 3-2: Different Motions supported by Bearing 3.2 Friction Reducing friction in bearings is often important for efficiency, to reduce wear and to facilitate extended use at high speeds and to avoid overheating and premature failure of the bearing. Essentially, a bearing can reduce friction by virtue of its shape, by its material, or by introducing and containing a fluid between surfaces or by separating the surfaces with an electromagnetic field. By shape, gains advantage usually by using spheres or rollers, or by forming flexure bearings. By material, exploits the nature of the bearing material used. (An example would be using plastics that have low surface friction.) By fluid, exploits the low viscosity of a layer of fluid, such as a lubricant or as a pressurized medium to keep the two solid parts from touching, or by reducing the normal force between them. By fields, exploits electromagnetic fields, such as magnetic fields, to keep solid parts from touching. Combinations of these can even be employed within the same bearing. An example of this is where the cage is made of plastic, and it separates the rollers/balls, which reduce friction by their shape and finish. Bearings vary greatly over the size and directions of forces that they can support. 62 | P a g e Forces can be predominately radial, axial or bending moments perpendicular to the main axis. 3.3 Service life 3.3.1 Fluid and magnetic bearings Fluid and magnetic bearings can have practically indefinite service lives. In practice, there are fluid bearings supporting high loads in hydroelectric plants that have been in nearly continuous service since about 1900 and which show no signs of wear. 3.3.2 Rolling element bearings Rolling element bearing life is determined by load, temperature, maintenance, lubrication, material defects, contamination, handling, installation and other factors. These factors can all have a significant effect on bearing life. For example, the service life of bearings in one application was extended dramatically by changing how the bearings were stored before installation and use, as vibrations during storage caused lubricant failure even when the only load on the bearing was its own weight, the resulting damage is often false brinelling. Bearing life is statistical: several samples of a given bearing will often exhibit a bell curve of service life, with a few samples showing significantly better or worse life. Bearing life varies because microscopic structure and contamination vary greatly even where macroscopically they seem identical. 3.3.3 Plain bearings For plain bearings some materials give much longer life than others. 3.3.4 Flexure bearings Flexure bearings rely on elastic properties of material. Flexure bearings bend a piece of material repeatedly. Some materials fail after repeated bending, even at low loads, but careful material selection and bearing design can make flexure bearing life indefinite. 63 | P a g e 3.3.5 Short-life bearings Although long bearing life is often desirable, it is sometimes not necessary. Harris describes a bearing for a rocket motor oxygen pump that gave several hours life, far in excess of the several tens of minutes life needed. 3.3.6 L10 life Bearings are often specified to give an "L10". This is the life at which ten percent of the bearings in that application can be expected to have failed due to classical fatigue failure (and not any other mode of failure like lubrication starvation, wrong mounting etc.), or, alternatively, the life at which ninety percent will still be operating. The L10 life of the bearing is theoretical life and may not represent service life of the bearing. Figure 3-3: Bearing Service Life 3.3.7 External factors The service life of the bearing is affected by many parameters that are not controlled by the bearing manufactures. For example, bearing mounting, temperature, exposure to external environment, lubricant cleanliness and electrical currents through bearings etc. 64 | P a g e 3.4 Classification of Bearings: Bearings are broadly categorized into two types: a) Fluid film b) Rolling contact type. 3.4.1 Fluid Film bearings: In fluid film bearing the entire load of the shaft is carried by a thin film of fluid present between the rotating and non-rotating elements. The types of fluid film bearings are as follows: a) Sliding contact type b) Journal bearing c) Thrust bearing d) Slider bearing 3.4.2 Rolling contact bearings: In rolling contact bearings, the rotating shaft load is carried by a series of balls or rollers placed between rotating and non-rotating elements. The rolling contact type bearings are of two types, namely: a) Ball bearing b) Roller bearing 3.4.3 Comparison of bearing frictions: The Fig. shows a plot of Friction vs. Shaft speed for three bearings. It is observed that for the lower shaft speeds the journal bearing have more friction than roller and ball bearing and ball bearing friction being the lowest. For this reason, the ball bearings and roller bearings are also called as anti-friction bearings. However, with the increase of shaft speed the friction in the ball and roller bearing phenomenally increases but the journal bearing friction is relatively lower than 65 | P a g e both of them. Hence, it is advantageous to use ball bearing and roller bearing at low speeds. Journal bearings are mostly suited for high speeds and high loads. Figure 3-4: Friction in Different Bearings The ball and roller bearings require less axial space but more diametrical space during installation and low maintenance cost compared to journal bearings. Ball bearings and roller bearing are relatively costly compared to a journal bearing. The reliability of journal bearing is more compared to that of ball and roller bearings. 3.4.4 Sliding contact bearings - Advantages and Disadvantages: These bearings have certain advantages over the rolling contact bearings. They are: 1) The design of the bearing and housing is simple. 2) They occupy less radial space and are more compact. 3) They cost less. 4) The design of shaft is simple. 5) They operate more silently. 6) They have good shock load capacity. 7) They are ideally suited for medium and high speed operation. The disadvantages are: 1) The frictional power loss is more. 66 | P a g e 2) They required good attention to lubrication. 3) They are normally designed to carry radial load or axial load only. 3.5 Journal Bearing: Among the sliding contact bearings, radial bearings find wide applications in industries and hence these bearings are dealt in more detail here. The radial bearings are also called journal or sleeve bearings. The portion of the shaft inside the bearing is called the journal and this portion needs better finish and specific property. Depending on the extent to which the bearing envelops the journal, these bearings are classified as full, partial and fitted bearings. As shown in Fig. Figure 3-5: Different Types of Journal Bearings Fig. 3-6 describes the operation of a journal bearing. The black annulus represents the bush and grey circle represents the shaft placed within an oil film shown by the shaded region. The shaft, called journal, carries a load P on it. The journal being smaller in diameter than the bush, it will always rotate with an eccentricity. 67 | P a g e Figure 3-6: Operation of a Journal Bearing When the journal is at rest, it is seen from the figure that due to bearing load P, the journal is in contact with the bush at the lower most position and there is no oil film between the bush and the journal. Now when the journal starts rotating, then at low speed condition, with the load P acting, it has a tendency to shift to its sides as shown in the figure. At this equilibrium position, the frictional force will balance the component of bearing load. In order to achieve the equilibrium, the journal orients itself with respect to the bush as shown in figure. The angle θ, shown for low speed condition, is the angle of friction. Normally at this condition either a metal to metal contact or an almost negligible oil film thickness will prevail. At the higher speed, the equilibrium position shifts and a continuous oil film will be created as indicated in the third figure above. This continuous fluid film has a converging zone, which is shown in the magnified view. It has been established that due to presence of the converging zone or wedge, the fluid film is capable of carrying huge load. If a wedge is taken in isolation, the pressure profile generated due to wedge action will be as shown in the magnified view. Hence, to build-up a positive pressure in a continuous fluid film, to support a load, a converging zone is necessary. Moreover, simultaneous presence of the converging and diverging zones ensures a fluid film continuity and flow of fluid. The journal bearings operate as per the above stated principle. 68 | P a g e 3.5.1 Design parameters of journal bearing: The first step for journal bearing design is determination of bearing pressure for the given design parameters: a) Operating conditions (temperature, speed and load) b) Geometrical parameters (length and diameter) c) Type of lubricant (viscosity) The design parameters, mentioned above, are to be selected for initiation of the design. The bearing pressure is known from the given load capacity and preliminary choice of bearing dimensions. After the bearing pressure is determined, a check for proper selection of design zone is required. The selection of design zone is explained below. 3.5.2 Selection of design zone: Figure 3-7: Friction variation with Bearing Characteristic number The Fig. shows the results of test of friction by McKee brothers. Figure shows a plot of variation of coefficient of friction with bearing characteristic number. Bearing characteristic number is defined as: 69 | P a g e It is a non-dimensional number, where: is the viscosity, N is the speed of the bearing and p is the pressure given by , d and l being diameter and length of the journal respectively. The plot shows that from B with the increase in bearing characteristic number the friction increases and from B to A with reduction in bearing characteristic number the friction again increases. So B is the limit and the zone between A to B is known as boundary lubrication or sometimes termed as imperfect lubrication. Imperfect lubrication means that metal – metal contact is possible or some form of oiliness will be present. The portion from B to D is known as the hydrodynamic lubrication. The calculated value of bearing characteristic number should be somewhere in the zone of C to D. This zone is characterized as design zone. For any operating point between C and D due to fluid friction certain amount of temperature generation takes place. Due to the rise in temperature the viscosity of the lubricant will decrease, thereby, the bearing characteristic number also decreases. Hence, the operating point will shift towards C, resulting in lowering of the friction and the temperature. As a consequence, the viscosity will again increase and will pull the bearing characteristic number towards the initial operating point. Thus a self-control phenomenon always exists. For this reason the design zone is considered between C and D. The lower limit of design zone is roughly five times the value at B. On the contrary, if the bearing characteristic number decreases beyond B then friction goes on increasing and temperature also increases and the operation becomes unstable. Therefore, it is observed that, bearing characteristic number controls the design of journal bearing and it is dependent of design parameters like, operating conditions (temperature, speed and load), geometrical parameters ( length and diameter) and viscosity of the lubricant. 70 | P a g e 3.6 Bearing Lubrication The object of lubrication is to reduce friction, wear and heating of machine parts that move relative to each other. A lubricant is any substance that when inserted between the moving surfaces, accomplishes these purposes. 3.6.1 Types of Lubrication Five distinct forms of lubrication may be identified: 1. Hydrodynamic 2. Hydrostatic 3. Elastohydrodynamic 4. Boundary 5. Solid film Hydrodynamic lubrication means that the load-carrying surfaces of the bearing are separated by a relatively thick film of lubricant, so as to prevent metal-to-metal contact. Hydrodynamic lubrication does not depend upon the introduction of the lubricant under pressure. The film pressure is created by the moving surface itself pulling the lubricant into a wedge-shaped zone at a velocity sufficiently high to create the pressure necessary to separate the surfaces against the load on the bearing. Hydrostatic lubrication is obtained by introducing the lubricant, which is sometimes air or water, into the load-bearing area at a pressure high enough to separate the surfaces with a relatively thick film of lubricant. This should be considered in designing bearings where the velocities are small or zero and where the frictional resistance is to be an absolute minimum. Elastohydrodynamic lubrication is the phenomenon that occurs when a lubricant is introduced between surfaces that are in rolling contact. Insufficient surface area, a drop in the velocity of the moving surface, a lessening in the quantity of lubricant delivered to a bearing, an increase in the bearing load, or an increase in lubricant temperature resulting in a decrease in viscosity – any one of these – may prevent the buildup of a film thick enough for full-film lubrication. When this happens, the highest asperities may be 71 | P a g e separated by lubricant films only several molecular dimensions in thickness. This is called Boundary lubrication. When bearings must be operated at extreme temperatures, a solid-film lubricant such as graphite or molybdenum disulfide must be used because the ordinary mineral oils are not satisfactory. 3.6.2 Stable Lubrication The difference between boundary and hydrodynamic lubrication can be explained by reference to the following figure. Figure 3-8: Regimes of Lubrication The plot is important because it defines stability of lubrication and helps us to understand hydrodynamic and boundary lubrication. A design constraint to keep thick film lubrication is to be sure that, N P 1.7(106 ) Suppose we are operating to the right of line BA (at N P 0.1 ) and something happens, say, an increase in lubricant temperature. This results in a lower viscosity and hence a smaller value of N . The coefficient of friction decreases, not as much heat is generated in shearing the P lubricant, and consequently the lubricant temperature drops. Thus the region to the right of line BA defines stable lubrication because variations are self-correcting. 72 | P a g e To the left of the line BA, a decrease in viscosity would increase the friction. A temperature rise would ensue, and the viscosity would be reduced still more. Thus the region to the left of line BA represents unstable lubrication. 73 | P a g e 3.7 General causes of bearing failure and Precautions 3.7.1 DIRT: 3.7.1.1 DIRT IN THE LUBRICATION SYSTEM The presence of dirt particles entrained in the lubrication system is one of the most frequent causes of bearing damage. The root of the problem is usually that the engine is not sufficiently clean. In line with the nature and size of the foreign particles, the bearing will exhibit a correspondingly lesser or greater degree of circumferential scratching and, usually, any debris that may have become embedded in the lining. Figure 3-9: DIRT IN THE LUBRICATION SYSTEM Recommendation: Ensure that all housings, in which bearings are to be seated, are carefully cleaned prior to assembly. 3.7.1.2 DIRT ON BEARING BACK The presence of a foreign particle trapped between the bearing back and its housing will lead to a raised area, with the ensuing risk of contact between this protruding high-spot and the journal. Signs of this will be seen in the area opposite the particle, along the inner surface of the bearing, where there will be evidence of marked localized wear. 74 | P a g e Figure 3-10: Dirt on Bearing Back Recommendation: The lubrication system must be thoroughly checked in order to pinpoint the cause of failure, which may be a blocked oil passage, an improperly installed bearing, an oil pump malfunction, etc. 3.7.2 INSUFFICIENT LUBRICATION 3.7.2.1 MALFUNCTION IN THE LUBRICATION SYSTEM A total absence of lubrication of the journal-bearing system leads to bearing seizure and, normally, to total destruction of the part. However an altogether more frequent phenomenon is fatigue due to oil starvation, whereby the amount of oil reaching the journal-bearing system is insufficient to maintain the oil film, leading to metal-to-metal contact between the two parts. Prolonged operation under such conditions will also result in total destruction of the whole. 75 | P a g e Figure 3-11: Bearing Failure due to Malfunctioning Lubrication Recommendation: The lubrication system must be thoroughly checked in order to pinpoint the cause of failure, which may be a blocked oil passage, an improperly installed bearing, an oil pump malfunction, etc. 3.7.2.2 OIL SEAL FAILURE In the example shown in the photograph, the failure of the crankshaft seal led to oil escaping at this point. The track of the pair of bearing shells nearest the seal exhibits symptoms of seizure, due to the oil film rupturing as a result of loss of oil pressure. The circumferential oil groove acted as a barrier to the defect, so that the other track of the bearing shells, as well as the two remaining pairs in the set, only exhibit shiny areas, a sign of oil starvation. Figure 3-12: Bearing Seizure due to oil film failure 76 | P a g e Recommendation: Check for possible loss of oil at the seals and replace these wherever necessary. 3.7.3 MISASSEMBLY 3.7.3.1 BEARING REVERSED Where a bearing having no oil hole is mistakenly fitted in a position in which it ought to have one, e.g., in a case where the upper and lower seats of a pair of main bearing shells are inadvertently switched, this effectively prevents that particular main journal receiving lubrication. As a consequence, no lubrication can reach the crankpin via such oil holes, eventually leading to seizure of the bearing in question. From the bearing back, it will be evident that the oil passage hole has been blocked off. Figure 3-13: Failure due to misplaced oil hole of the bearing Recommendation: Ensure that the utmost precaution is taken during the installation of new bearings and that the correct positioning of each is double checked. 3.7.4 IMPROPER MACHINING OF COMPONENTS. 3.7.4.1 IMPROPERLY GROUND HOUSING (FACETED OR POLYGONAL) Where a housing bore becomes flawed due to engine vibration or some other cause that gives rise to marked out-of-roundness, the bearing will tend to conform to the defective shape of its housing. It will display alternating bands of heavy and normal wear. This defect can lead to metal fatigue. 77 | P a g e Figure 3-14: Failure Due to Improperly Ground Housing Recommendation: Check for correct grinding of shaft and housing. 3.7.4.2 FILLET RIDE If the radius of the fillet is increased during the course of a repair to the crankpin, the edge of the bearing may make metal-to-metal contact with the fillet, and will also hinder oil flow. In the photograph, the bearing exhibits signs of incipient damage, with its edge rounded from rubbing against the fillet. Figure 3-15: Failure due to Fillet Ride Recommendation: Use a grindstone in perfect condition to achieve correct crankshaft geometry. 3.7.4.3 MISALIGNMENT OF SHAFT AND HOUSING There are a number of causes that give rise to misalignment of the crankshaft and cylinder-block housings, such as improper machining, bent crankshaft, distorted cylinder block, etc. These defects result in localized wear, which tends to be greatest on some of the main bearings and less pronounced on others. 78 | P a g e Figure 3-16: Misaligned Shaft leads to Bearing Failure Recommendation: Ensure that cylinder-block and crankshaft machining tolerances are in accordance with the engine manufacturer‟s specifications. 3.7.4.4 INSUFFICIENT CRUSH Total contact between the bearing back and housing is fundamental to ensure good heat transfer and a correct seating of the part. If crush is insufficient, the bearing will move back and forth within the housing and shiny areas will be visible on the bearing back due to friction with the housing. On other occasions, discolorations or stains may appear evidence of burnt oil that has worked its way into the space between the two surfaces. Figure 3-17: Failure due to Insufficient Crush 79 | P a g e Recommendation: Ensure that the size of the housing bore and torquing are in accordance with the manufacturer‟s recommendations. 3.7.5 OVERLOADING Where operating conditions cause excessive load to be exerted upon the bearings, this leads to damage due to metal fatigue Figure 3-18: Bearing Failure due to Overloading Figure 3-19: Metal Fatigue caused by Overloading Recommendation: Check that the assembly clearances and bearing material are as specified for the application in question. Similarly, ensure that engine-tuning conditions are respected. 3.7.6 CORROSION Oil in poor condition can damage the bearing surface. This effect is due to dilution of the lead in the alloy by certain of the compounds produced by oil degradation. 80 | P a g e Figure 3-20: Bearing Corrosion due to wrong Lube Oil Recommendation: Always use the oil recommended by the manufacturer, and perform the scheduled oil changes as indicated in the vehicle maintenance manual. 3.7.7 CAVITATION Under certain operating conditions, oil pressure drops locally, producing vapour bubbles that cause damage to the bearing surface. This damage will be evident in certain bearing areas, such as oil grooves or holes, which are affected by discontinuities in the oil flow. Figure 3-21: Cavitation in Bearing Recommendation: Check that lubrication conditions, such as oil pressure, flow rate and type, are as stipulated by the vehicle manufacturer. 81 | P a g e 3.8 Diesel Loco Specification 3.8.1 Diesel Locomotive Model: WDP3A Service Type: Passenger service Track Type: Broad Gauge Engine name: Upgraded fuel efficient 251B engine Number of Cylinders: 16 Horse Power: 3100 hp gross power Axle load: 19.5 tonne Maximum operating speed: 160 km/h Bogie Type: Co-Co 2-stage 3-axle flexi coil bogie Number of bearings: 9 Bearing Material: No. of bolts: Bolt Diameter: Bearing Diameter: Journal Diameter: 82 | P a g e 3.8.2 Diesel Locomotive Model: WDP1 Service Type: Passenger service Track Type: Broad Gauge Engine name: Upgraded fuel efficient 251B engine Number of Cylinders: 12 Horse Power: 2300 hp gross power Axle load: 20.0 tonne Maximum operating speed: 120 km/h Bogie Type: Two stage flexi-coil suspension Bo-Bo bogie Number of bearings: 7 Bearing Material: No. of bolts: Bolt Diameter: Bearing Diameter: Journal Diameter: 83 | P a g e 3.9 Main Bearing Failure Cases 3.9.1 Loco No. 14004: Arrived in shed on 04.03.2011 as dead with empty water tank. On examination its water pump gear was found lying in engine sump after breakage of water pump shaft. On further checking few metallic chips were found in engine crank case No.1 to 5. On removal of Cylinder Head and Main bearing, all power assemblies & Main Bearing were found seized. Water pump SS Shaft was found broken which caused overheating of power pack due to non-circulation of water. Engine oil could not sustain its property and lead to seizure of all power assemblies & main bearings along with draining out of water through pressure cap after boiling. CONCLUSION After breakage of water pump shaft, temperature of power pack had increased above 100°C due to non-circulation of water. Due to the resulting high temperature, engine oil could not sustain its lubricating properly and lead to seizure of all power assemblies and main bearing along with draining out of all water after boiling. 3.9.2 Loco No. 15530: On examination, metal chips were found in No.2 crank case. On further checking, its crank shaft was found broken from Expresser side web portion at No.2 journal. No.2 main bearing also seems to have been seized. This crank shaft and engine block were fitted at CB Shop/LKO during POH+SR in Sept‟2006.There was no water in expansion tank. It is observed that crank shaft developed cracks internally and on the surface later with seizure of No.2 main bearing leaving behind crank shaft broken at No.2 crank pin web portion. Due to the seizure of main bearing no.2, both power assemblies seized consequently and caused cracking of liner at top which lead to draining out of water. Crank shaft was broken first with initiation from inner texture and lead to breakage of crank shaft at web portion. 84 | P a g e CONCLUSION This crank shaft was removed from loco No.17906 & fitted on this loco during its POH schedule in Sept. 2006 .It is observed that crank shaft was already distorted internally and surfaced in the form of this breakage during service of locomotive. 3.9.3 Loco No. 15508: Arrived in the shed on 12.01.2010 in working condition. During examination in the shed, metal chips were found in No.7 crank case sump. On further examination its No.7 Main Bearing was found seized. R-6 & L-6 Connecting Rod bearing shells were also observed to have scoring marks. Main Bearing No.7 was found badly metal flaked and this caused the consequential effect on both L-6 & R-6 Connecting Rod bearing shell in the form of deep scoring mark. Fine chips of bearing shell material were also found on lube oil strainer and filter elements. CONCLUSION The main bearing was last fitted in POH in Oct’2007 when this loco was taken in M24 schedule in the month of December’2009. The location 7 Main Bearing had scored mark. Crank shaft & saddle were polished and fitted during M24 schedule in shed. But again this bearing seized on 12.01.2010. During Yearly schedule, the main bearing temperature difference across consecutive bearing was also within the permissible range. Reverse elongation was also within the range. It appears that during overhauling of bearing, the contact area of bearing with saddle was less (70%) which lead to breakage of hydro-dynamic film at higher temperature and seizure of main bearings. 3.9.4 Loco No 15527: Was detained for M-24 schedule in normal working condition. During stripping, its Main Bearing No.8 shell was found broken after overheating and working out of bearing material, though its spectrographic report was normal and there was no sign of any abnormality either on No.7 crank pins or Power assemblies. The history sheet of this loco also indicated that this loco was not involved either in main bearing or power assembly‟s seizure or any hydraulic locking. It was observed in the last moment of its working before being detaining for M-24 schedule, the main bearing breakage had caused 85 | P a g e distortion of the crank pin internally which surfaced only along with the seizure of the connecting rod within short period of service after M24 schedule. CONCLUSION Breakage of crank pin No.7 occurred at an angle of 45° started from Radial fillet at Main Journal No.8. It is a case of fatigue failure which progressed fast. There must be any notch which acted as stress raiser and fatigue developed from there. 86 | P a g e 3.10 FINAL CONCLUSION of THE PROJECT From the available main bearing failure cases from the CTA Cell it is apparent that of the 4 bearing failure reports, only one was caused due to the improper fitting of the main bearing, rest all were initiated by some other defect or malfunctioning in the Loco Engine. Moreover, there is no repetitive pattern or cause of main bearing failure. On the basis of study of above cases, we can safely conclude that the maintenance work carried out by the technicians at various diesel sheds across India are generally following correct procedures for servicing, since the major cause of failure is not dust, rather some other defect or malfunctioning of Diesel Loco‟s engine component. In order to prevent or reduce the rate of failure of main bearing/crankshaft and engine in the future, we have suggested a few steps which can be further implemented to further reduce the rate of engine failures. 87 | P a g e 3.11 Ways to improve bearing life and performance The following precautions can be taken while servicing the main bearing to increase its life:1) Bearing should be properly cleaned before assembly, as dirt is the primary cause of bearing failure. Moreover, any clogged holes for lubrication, will starve the bearing of the lubricating oils, thereby resulting in pre mature failure of bearing. 2) The bearing should be assembled properly and the holding screws shouldn’t be tightened above or below the required stresses, as faulty assembly and overloading of engine bearing results in near imminent failure of the same. 3) Use of hydraulic bolt tensioner for tightening the holding bolts on the main bearing and other engine assembly. Since, the use improper tools and processes to carry out this operation correctly in bolted assemblies is a major cause of failure. Hence the use of hydraulic bolt tensioner may be used for tightening the bolts in the engine assembly. The added benefits of the same are:a) No torsion stress b) Good accuracy c) Easy implementation d) No damage to components e) Process automation possible 88 | P a g e Figure 3-22: Hydraulic Bolt Tensioner 4) In case the capital investment for hydraulic bolt tensioner can’t be made a torque wrench can be used. A torque wrench is a tool used to precisely apply a specific torque to a fastener such as a nut or bolt. It was designed to prevent over tightening bolts. 5) The bearing should be aligned properly while the crank is being fitted in the crank case, as misalignment is also one of the most prominent causes of failure. 6) Digital gauges can be used for measurement of re-machined bearing rather than analogue, so as to ensure the correct reading is taken into account. 89 | P a g e 4 General Discipline Parameters influencing performance of the diesel shed are as follows: 1) Outage or Target (target is fixed by Railway board) If more, then outage = +ve If less, then outage = -ve 2) Total number of failure/ Total number of setouts 3) Reliability of locos (between Periodicity, it should not fail) 4) Punctuality (if 3 trains get late due to failure of loco) 5) Lube oil Consumption (Average) 6) Specific Fuel Consumption 7) Environment and health of employee 8) Number of employees available in diesel shed 9) Infrastructure of shed 10) Quantity of diesel used within the shed During our training at the Tughlakabad Diesel Locomotive shed, we were able to observe the work culture and the general attitude of the shed in detail. On the basis of our observation we were impressed and humbled by the quality of workmanship and dedication of the workers and staff at the shed. Even though the shed is operating and maintaining very high quality of service, we believe if the following suggestions if implemented will further improve the performance of the shed. 4.1 Suggestions To Improve Performance of the Shed The suggestions are as stated below:Upgradation of equipments and tools, so that not only the quality of repair and work improves but also the stress on the technicians and impact on environment is reduced. 90 | P a g e Some of the equipments we do like to see changed are:1) Adoption of Hydraulic Bolt Tensioner or Torque Wrench to tighten all bolts. The use of any of the two above mentioned tools will result in the bolts being tightened to appropriate tension only, thereby reducing or eliminating the chance of the bolts being under or over tightened. If budget is not an issue we would like the shed to use Hydraulic Bolt Tensioner for tightening bolt, as its use will not only result in better workmanship but also in reduced fatigue in workers, which shall also improve the amount work done in a day and the quality of work. 2) Use of MIG welding to perform the welding operations wherever necessary. The advantage of MIG welding is that it has higher penetration and lower chance of weld contamination compared to arc welding, thereby resulting in stronger welds. 3) Whenever the measuring instruments are replaced, they be replaced with digital measuring instruments, so that measuring time is reduced. 4) Establishment of a proper paint shop, where painting is carried out using a spray gun rather than brush. The use of a spray gun reduces the time of painting. We would also like to suggest that, all the locomotives arriving at the shed and the repair work being carried out on them needs to be also maintained in a computer database. This shall help in identifying the locomotive or component that is most likely to fail and hence special attention to the same can be given during scheduled maintenance. Moreover, this data can be sent to the designers at RDSO and Diesel Loco Factories of Indian Railways, which shall help them in improving the design of the failure prone component and also help in designing better locomotives in the future. 4.2 Improvement in Working Conditions We were not impressed by the amount of facilities provided for the worker comfort. We request the concerned authority to consider the following suggestions:1) The number of fans in the loco shed should be increased considerably, so as to increase the comfort for workers. 91 | P a g e 2) Wearing of earplugs/earmuffs. Since the working environment is very noisy and which may lead to hearing loss of workers. Also all workers should be asked to undergo audiometry test every year. Figure 4-1: Earmuffs reduce External Noise 3) The cleanliness of the canteen needs to be increased. 4) All workers should be provided with gloves for handling hazardous chemicals and sharp objects. They should also be provided with safety glasses. 5) The quality and cleanliness of the restrooms needs to be improved considerably. 4.3 Reduction in Environmental Impact Steps that can be considered for making the Tughlakabad Diesel Loco Shed more environmentally friendly are: 1) All the existing lighting can be replaced systematically with LED lights. 2) Lubricating oils need to be used carefully, as any spillage of the same results in environmental degradation. 92 | P a g e