DIESEL TRAINING CENTREDIESEL LOCO SHEDTUGHLAKABAD PROJECT REPORTSUBMITTED BY:PRAVEEN KUMAR GOND

ACKNOWLEDGEMENT

We take this opportunity to express our sincere gratitude to the peoples who have been helpful in the successful completion of our industrial training and this project. We would like to show our greatest appreciation to the highly esteemed and devoted technical staff, supervisors of the Diesel Loco Shed, Tughlakabad. We are highly indebted to them for their tremendous support and help during the completion of our training and project.

INDIAN RAILWAY HISTORY

Indian Railways is the state-owned railway company of India. It comes under the Ministry of Railways. Indian Railways has one of the largest and busiest rail networks in the world, transporting over 18 million passengers and more than 2 million tonnes of freight daily. Its revenue is Rs.107.66 billion. It is the world's largest commercial employer, with more than 1.4million employees. It operates rail transport on 6,909 stations over a total route length of more than 63,327kilometers(39,350miles).The fleet of Indian railway includes over 200,000 (freight) wagons, 50,000 coaches and 8,000 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. The total length of track used by Indian Railways is about 108,805km (67,608mi) while the total route length of the network is 63,465km (39,435mi). About 40% of the total track kilometer is electrified & almost all electrified sections use 25,000V AC. Indian railways uses four rail track gauges|~|

Indian railways uses four rail track gauges:1. The broad gauge (1670 mm)2. The meter gauge (1000 mm)3. Narrow gauge (762mm)4. Narrow gauge (610mm). Indian Railways operates about 9,000 passenger trains and transports 18 million passengers daily .Indian Railways makes 70% of its revenues and most of its profits from the freight sector, and uses these profits to cross-subsidies the loss-making passenger sector. The Rajdhani Express and Shatabdi Express are the fastest trains of IndiaCLASSIFICATION 1. 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)2. Type of Traction designations:- D = Diesel-electric traction C = DC traction A = AC traction CA=Dual power AC/DC traction3. The type of load or Service designations:- M= Mixed service P = Passenger G= Goods S = Shunting4. 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.

What is diesel shed ?It is a place where repair and maintenance work of diesel locomotivesIs carried out so as to increases its life and efficiency and to reduceline failures to a minimum extent.

Diesel Shed TKDTughlakabad is one such premier shed in Northern Railways homing162 Diesel Locos. Because of its geographical location and beingIn the capital, it serves a large number of Mails /Express trains which across the length & breadth of the country casting to goods operation.Diesel Shed, Tughlakabad is spread over an area of 1,10,000 m 2 out of Which 10,858 m2 is covered.Diesel Shed ,Tughlakabad was established in the year 1970 with a plannedHolding of 75 locomotives and initial holding of 26 WDM2 locomotives.

DIESEL SHED TUGHLAKABAD

INTRODUCTIONDiesel 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. ABOUT DIESEL SHED TKD 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.

AT A GLANCE Inception 22nd April1970

Present Holding 147 Locomotives 19 WDM2 37 WDM3A 08 WDM3D 11 WDG3A 46 WDP1 26 WDP3AAccreditation ISO-9001-2000 & ISO 14001

Covered area of shed 10858 SQ. MTR

Total Area of shed 1, 10,000 SQ. MTRStaff strength sanction 1357 On roll - 1201 Berthing capacity 17 locomotives

SPECIAL MACHINES & PLANTPit wheel lathe machine This machine is suitable for turn & re-profiles the wheels of locomotives. 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. 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 under.Expressor performance test notch wise Simulation of test stand facility on the loco itself with the help of only two small fixtures. Testing the performance of expressor in diesel locomotive engines.

Cylinder head Stud Removal/ Tightening Arrangement A simple device has been developed to help reduce the time and effort taken in removal/tightening of cylinder head studs.

Diesel Training Centre-DTC It was setup in the TKD shed premises in 1975 by the Northern Railway with view to train diesel loco pilots. It also trains the Diesel Maintenance staff to improve the availability of qualified manpower and improve the efficiency of and quality of the technicians. It has five classrooms, a hall ,a Model room(with sectional models of TSC, expressor, cylinder head LOP, governor etc.). A well qualified team of instructors from the electrical and mechanical fields provides a quality training to the p=loco pilots and other trainees.Courses offered :- (regular) Diesel Assistant to Diesel Loco Driver promotion course Diesel Assistant Refresher coarse Diesel Driver refresher courseOther courses:- Up gradation course of Diesel technicians Electric traction to diesel traction conversion course Course for Drivers, Shunters and Asstt. Drivers 3 years Apprentice technician(Diesel mechanical and electrical) 6 months Apprentice Technician(Diesel mechanical and electrical) Vocational industrial training for B.Tech and Diploma student

1.FUEL SECTION

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 liters.This stock is enough to end for 15-16 days The fuel is supplied by truck from IOC - Panipat refinery each truck diesel sample is treated in diesel lab and after it in unloaded. Sample check is necessary to avoid water, kerosene mixing diesel. Two fuel filling points are established near the control room It also 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.

2.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 over due 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 liters/ total kms travelled 100

New and better operational loco have less LOC.

3.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 analyzed 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.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.

TURBO SUPERCHARGER

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 compresser 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.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 effects 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.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.

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.

LUBRICATING, COOLING AND AIR CUSHIONINGLUBRICATING SYSTEM

One branch line from the lubricating system of the engine is connected to the turbo- supercharger. 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. 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.

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.AFTER COOLERIt 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.

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 TYPEPOWERCOOLING

1.ALCO2600HPWater cooled

2.ABB TPL613100HPAir cooled

3.HISPANO SUIZA HS 5800 NG3100HPAir cooled

4. GE 7S17163100HPWater cooled

5. NAPIER NA-2952300,2600&3100HPWater cooled

6. ABB VTC 3042300,2600&3100HPWater cooled

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 thenshut 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.

ROTOR BALANCING MACHINE A balancing machine is a measuring tool used for balancing rotating machine parts such as rotors of turbo subercharger,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.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 engineBetter fuel efficiency due to complete combustion of fuel .Defect in Turbochargers Low Booster Air Pressure (BAP).Oil throwing from Turbocharger because of seal damage or out of clearance. Surging- Back Pressure due to uneven gap in Nozzle Ring or Diffuser Ring. Must change components of Turbocharger. Intermediate casing gasket. Water outlet pipe flange gasket. Water inlet pipe flange gasket. Lube Oil inlet pipe rubber o ring. Turbine end Bearing. Blower end Bearing. Chimney gasket. Rubber o Ring kit. Spring Washers.Lock Washer Rotor Stud

FUEL OIL SYSTEM

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 atomised. The system injects into the cylinder correctly metered amount of fuel in highly atomised 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 atomisation 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.

FUEL OIL SYSTEM

The fuel oil system consists of two integrated systems. These are- FUEL INJECTION PUMP (F.I.P). FUEL INJECTION SYSTEM.

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 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. 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 poweroutput is not the maximum. When the helix is not in alignment with the spill port through out 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.

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.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.

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.Dia.of element(mm)Rack(mm)Required volume of fuel(cc)

15 mm30 mm(full load)

9 mm(Idling)351 cc +5/-10

34 cc +1/-5

17 mm28 mm (full load)

9 mm (Idling)401 cc +4/-11

45 cc +1/-5

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.

EXPRESSOR________________________________________ 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. 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.

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 open or close 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.

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 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 inter-cooler. This is an air to air cooler where compressed air passes through the element tubes and cool atmospheric air is blown on the out side 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 high- pressure 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.

AIR BRAKES INTRODUCTION An air brake is a conveyance braking system actuated by compressed air. Modern trains rely upon a fail preventive air brake system that is based upon a design patented by George Westinghouse on March 5,1872. In the air brake's simplest form, called the straight air system, compressed air pushes on a piston in a cylinder. The piston is connected through mechanical linkage to brake shoes that can rub on the train wheels, using the resulting friction to slow the train.AIR BRAKE SYSTEM OPERATION The compressor in the locomotive produces the air supplied to the system. It is stored in the main reservoir. Regulated pressure of 6 kg/cm2 flows to the feed pipe through feed valve and 5-kg/cm2 pressure by drivers brake valve to the brake pipe. The feed pipe through check valve charges air reservoir via isolating cock and also by brake pipe through distributor valve. The brake pipe pressure controls the distributor valves of all the coaches/wagons which in turn control the flow of compressed air from Air reservoir to break cylinder in application and from brake cylinder to atmosphere in release.During application, the driver in the loco lowers the BP pressure. This brake pipe pressure reduction causes opening of brake cylinder inlet passage and simultaneously closing of brake cylinder outlet passage of the distributor valve. In this situation, auxiliary reservoir supplies air to brake cylinder. At application time, pressure in the brake cylinder and other brake characteristics are controlled by distributor valve.During release, the BP pressure is raised to 5 kg/cm2 . This brake pipe pressure causes closing of brake cylinder inlet passage and simultaneously opening of brake cylinder outlet passage of the distributor valve.LAYOUT:-

The distributor valve connects brake cylinder to atmosphere. The brake cylinder pressure can be raised or lowered in steps.In case of application by alarm chain pulling, the passenger emergency alarm signal device (PEASD) is operated which in turn actuates passenger valve (PEV) causing exhaust of BP pressure through a choke of 4 mm. Opening of guard emergency brake valve also makes emergency brake application. There are two case of braking, when only loco move and when entire train move. Consequently there are two valves in the driver cabin viz SA-9&A-9. Braking operation of above case is shown in chart below. VALVES A-9 Valve The A-9 Automatic Brake Valve is a compact self lapping, pressure maintaining Brake Valve which is capable of graduating the application or release of locomotive and train brakes. A-9 Automatic Brake Valve has five positions: Release, minimum Reduction, Full Service, Over Reduction and Emergency.SA-9 Valve SA-9 Independent Brake Valve is a compact self lapping, pressure maintaining Brake Valve which is capable of graduating the application or release of Locomotive Air Brakes independent of Automatic Brake. The SA-9 Independent Brake Valve is also capable of releasing an automatic brake application on the Locomotive without affecting the train brake application. The SA-9 Brake Valve has three positions : quick release, release and application.MU 2B VALVEThe MU-2B Valve is a manually operated, two positions and multiple operated valve arranged with a pipe bracket and is normally used for locomotive brake equipment for multiple unit service between locomotives equipped with similar system in conjunction with F-1 Selector Valve.

D-1 Emergency Brake ValveThe D-1 Emergency Brake Valve is a manually operated device

Which provides a means of initiating an emergency brake application.

CYLINDER HEAD

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.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. 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 donein 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.Benefits:- Better heat dissipation Failure reduced by reducing crack and eliminating sagging effect of fire deck area.Maintenance and InspectionCleaning: By dipping in a tank containing caustic solution or ORION-355 solution with water (1:5) supported by air agitation and heating.Crack Inspection: Check face cracks and inserts cracks by dye penetration test.Hydraulic Test: Conduct hyd. test (at 70 psi, 200F for 30 min.) for checking water leakage at nozzle sleeve, ferrule, core plugs and combustion face.Dimensional check : Face seat thickness: within 0.005" to 0.020"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"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.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 (65C) 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.YEARLY/MECHANICAL

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: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.(8). Examination of piston for cracks, renew bearing shell of connecting rod fitment. Checking of connecting rod elongation.(9). Checking of crankshaft thrust and deflection. Shims are added if deflection is more then the tolerance limit.(10). Main bearing is discarded if it has embedded dust, gives evidence of fatigue failure or is weared. (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.(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 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.Examination while Engine is running.(32). Expressor orifice test is performed. Engine over sped 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 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. (33). 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.(37). Speedometer- Overhaul, testing of speed recorder and indicator, pulse generator is done. (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. (39). Additional items for WDP2 locos:-Checking for cracks 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.

SPEEDOMETER

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 drivers 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 drivers 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. 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 of stepper motor which rotates the pointer up to the desired position. A feed back 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 unitTELPRO is used in the most of the locomotive. Features and other technical specification of this speedometer are given below. 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 Stepless 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 Graphical and tabular reports generation for easy analysing of recorded data Cumulative, Trip-wise, Train-wise, Driver-wise and Date-wise report generation Master-Slave configurationApplications Speed indication for driver. Administrative control of traction vehicle for traffic scheduling. Vehicle trend analysis in case of derailment/accident.Analysis of drivers operational performance to provide training, if required

PROJECT WORKEXPRESSOR/COMPRESSOR1. TO STUDY THE OVERHAULING PRACTICES OF EXPRESSOR / COMPRESSOR.2. TOS TUDY THE PROBLEM OF LOADING UNLOADING ON LOCOS FITTED WITH AIR DRYERSAND SUGGEST SOLUTIONS AFTER SEARCHING WEB ABOUT LATEST MAINTENANCE PRACTICES FOLLOWED IN OTHER COUNTRIES.3. TO STUDY CASES OF FIRE IN EXPRESSOR AND SUGGEST PREVENTIVE MEASURES TO ARREST FIRE CASES IN EXPRESSOR.

EXPRESSOR (6CD, 4 UC, Compressor Exhauster) Working of expressorThe Expressor is located at the free end of the engine bloke and driven through the extension shaft attached to the engine crankshaft. Expressor is a combined unit of exhauster and compressor. The main function of exhauster unit is to create vacuum 22 in train pipe. Air from vacuum train pipe is drawn into the exhauster cylinders through the inlet valves during its suction stroke and that air is thrown out to atmosphere during compression stroke through discharge valves.The main function of compressor unit is to create air pressure in main reservoir of locomotive up to 10kg/cm2. Atmosphere air is drown into the compressor LP cylinder through the open inlet valves during suction stroke and same air is discharged to HP cylinder through discharge and delivery pipe. The HP cylinders compresses the air at high pressure and discharge it in main reservoir of locomotive for the use of brake system.The expressor consists of the following components mainly; 1. Crank Case 2. Crank shaft 3. Four/Three exhauster cylinders with cylinder heads 4. One/Two low pressure compressor cylinder with cylinder head. 5. One high pressure cylinder with cylinder head. 6. Six pistons with connecting rods (including one/two LP, one HP and four/three exhausters.)1. Lube oil pump.

Models of Expressors used in Diesel Locos

There are two models commonly used in Diesel Locos. They are

1. 6CD-4UC

2. 6CD-3UC In 6CD-4UC Expressor, there are six cylinders out of which the one having smaller diameter acts as HP and one LP and four exhausters while in 6CD-3UC, there are one HP, two LP and three exhausters.

In both models, the LP cylinder head and each exhaust cylinder head contains two inlet and two discharge valves and the HP cylinder head contains one/two inlet and discharge valves. The valves are such that they have liberal air flow passages to avoid flow restrictions and to prevent excessive heating and choking of valve ports with carbon deposits due thermal decomposition of lube oil. The retainer stud in both the assemblies must project upward to avoid hitting the piston. The inlet valves of both LP and HP cylinders are equipped with unloaders which help to unload the compressor when the desired pressure in the main air reservoir is reached. Similarly, the compressor cylinders are loaded whenever there is a drop in air pressure.

LOADING AND UNLOADING OF COMPRESSOR

To avoid the compressor running hot due to overloading and also to avoid the wastage of engine horse power, arrangements are provided to unload the compressor when a particular pressure is reached. In other words the compessor cylinders are not required to compress air any further when the main reservoir pressure reaches 10 kg/sq.cm. So the compressor stops loading the main reservoir. Due to no further compression being done, reservoir pressure naturally falls due to normal consumption and leakages. When the M.R. pressure comes down to 8 kg/sq.cm. the compressor resumes loading of the M.R. again.

Basically in these compressors unloading is effected by the unloader plunger prongs pressing down the inlet valves of both L.P. & H.P. cylinders to keep them in open position as soon as 10kg pressure is reached in the M.R. It continues to be so till the pressure comes down to 8 kg/sq.cm. Thus the compressor remains unloaded or releived of load in the range between 10 to 8 kg/sq.cm. M.R. pressure. In this case,the L.P. cylinder air drawn in through the intake filter is thrown out in the same direction. In case of the H.P. cylinder air is pushed back to the inter cooler and L.P. discharge manifold. This is achieved through the function of the unloader plunger in conjuction with the air governor.

NS - 16 AIR GOVERNOR

The function of the air govornor is to transmit main air reservoir pressure to the top of unloader plunger as soon as the MR pressure reaches 10 kg/sq.cm. With the fall of pressure to 8kg. the same supply is discontinued and existing pressure in the unloader valve is vented out. This actions keep the suction valve open when loading of MR is not required any more and again allow the compressor to work normally for loading when needed.

The NS-16 air govornor consists of govornor body in two pieces of bronze castings and a pipe bracket with a number of air passages. It also incorporates (1) wire mesh filter (2) cut out cock (3) cut out adjusting stem (4) cut out valve spring (5) cut out valve spring adjusting nut (6) cut in tail valve (7) cut in valve (8) cut in valve adjusting stem (9) cut in valve spring (10) cut in valve adjusting nut.

When MR pressure gets access into the air governor through pipe A, it passes through the filter (1) to passage B and then bifurcates in the pipe bracket. A part of this air passes through the passage C at the bottom of the cut out valve. The other portion of the air passes through passage D and work on the cut in tail valve.

Once the MR pressure reaches 10 kg. the pressure acting at the bottom of the cut out valve overcomes the cut out valve spring tension and lifts the valve to get access to passage E. The air pressure acting on cut in tail valve lifts the cut in valve thereby opening the passage from E to F which leads to the top of the unloader plunger. At the same time the exhaust passage G of the casting is blocked by the upper lips of cut in valve.

Once the MR pressure goes below 10kg. but remains above 8kg.the cut out valve spring forces the cut out valve to be seated and the passage from C to E is blocked. But the cut in valve is still kept up with the help of pressure between 10kg to 8kg and the amount of air passing through the cut in tail valve keeps on supplying air to the unloader valve top.

As soon as the MR pressure drops to 8kg., or below the cut in valve spring closes the valve and thereby block the passage to F and no further air is supplied to the top of unloader. Further, whatever air is there in the pipe line is exhausted as soon as the cut in tail valve upper lips move down opening the connecting passage G to exhaust port.

LUBRICATION

The lube oil system of the expressor is a seperate system indipendent of the lube oil system of the engine. Lubricating oil of SAE 30 or SAE 40 grade is filled in the sump of 21 lts. capacity. A gear type pump under hung from the crank- shaft journal and is driven through sproket and chain. The sump oil is sucked through a strainer filter screen by the pump and then circulate the same to the journal bearings at a pressure between 45 psito 60 psi. It also lubricates the small end bush of the connecting rods and the cylinder liners. A connection is taken from the pump housing to the stem valve , lift of which indicates adequacy of oil pressure. A relief valve is also provided to release oil pressure in case the pressure in the system is beyond its usual limit.

EXPRESSOR CRANK CASE VACUUM

The expressor crank case must have some vacuum to prevent oil throw over through the exhaust by preventing development of pressure in the crank case.

Crank case vacuum is maintained by connecting the vacuum pipe to the crank case by a pipe connection through the crank case vacuum maintaining valve. Normally in well maintained expressors a differential of 5" of vacuum is considered ideal. In other words when train pipe vacuum is 22", the crank case vacuum should be 17". It has been experienced that oil throw over and sticking of expressor valves (with its consequential adverse effects) are inversely proportional to the amount of crank case vacuum. It is advisable to take expressor for attention, once the crank case vacuum drops below 15".

ALIGNMENT OF EXPRESSOR

Though the expressor is coupled up with the engine extension shaft through the medium of flexiable splined coupling, special care has to be taken for ensuring proper alignment at the time of installation. The following checks are required to be made :-

(1) SHAFT SEPERATION - While installing the expressor it is to be ensured that a gap is left between the expressor crank -shaft and the engine crank- shaft ends. A maximum of 9/16" is recommended to be maintained between the two ends.

Similarly distance of maximum 3.3/8" and minimum of 3.1/8" is required to be maintained between the two hubs which are shrunk fitted on to the taper ends of engine extension shaft and expressor crank shaft. To determine the correct hub seperation and shaft seperation, as mentioned above, the distance from from the end of each sleeve to the end of the hub is to be measured without dismantling the expressor. The distance should be between 2.1/2" to 2.3/4"

(2) ANGULAR MISALIGNMENT - During installation of the expressor it can suffer from angular misalignment in vertical plane, horigental plane or may be a combination of both. In order to ensure that there is no angular misalignment the distance between the two hubs should be kept equal all round the circumference of the hub face. A tolerance of + 0.006 only is permissible. This measurement is to be taken at the outer circumference of the hub-face with the help of micrometer at every 90 degree.

(3) OFF-SET MISALIGNMENT - There may not be any angular misalignment, but there may be off-set misalignment. For checking off-set misalignment use a dial indicator, fitted on the expressor crank shaft nut with suitable clamping arrangement. While the crank -shaft is manually rotated with the help of expressor cooing fan and the limit of 0.0008" is to be maintained.

Judicious use of jack screws is to be made for insurting or removing shims at the base for correction of misalignment and also for lateral shifting of the expressor.

(4) BACK - LASH - In view of the facts that the couplings are splined type flexible couplings, some amount of clearance between the male and female couplings are provided. Back -lash of 0.024" at 3.1/2" radius is to be maintained when new. Thus, when two sleeves are coupled together a total back- lash of 0.50" should be there. The maximum limit permitted after use is 0.001" at 3.1/2" radious. The back -lash mesurement is also done with the help of a dial indicator while moving the sleeve by hand.

FIRE PREVENTION MEASURES IN DIESEL LOCOS:1. Batteries and battery cables: Lack of electrolyte, Over charging of battery may result in internal short circuit in the battery cells and cause fire. If any indication of overcharging in BA (Battery Ammeter) as noticed by the crew of the loco, it is advised to check the condition of batteries located on loco for any short circuit. If anything is found, the cable may be isolated. Still, if the BA shows overcharging, loco crew is required to open battery knife switch provided in the nose compartment.2. Power circuit: a) Loss of insulation of power cables between traction generator and traction motors which are connected through BKTs, reverser and power contactors may result in short circuit and finally cause fire. Such type of fire accidents normally shows symptoms of smell/smoke of burning of cable insulation. So, crew on notice of such symptoms immediately notch down the throttle to idle, GF switch to OFF and Reverser to neutral position. b) Presence of foreign body on the BKT, Reverser, Power contactors etc., also cause fire on locomotive due to short circuit. In such cases GR trips normally and brings generator power cut-off. Ensure that no foreign material like tools, etc., are left if they open control panel doors for any purpose. Before resetting GR, an inspection shall be made for any foreign materials in the above items of the power circuit. Power ground: A foreign body or internal short circuit (Flash-over) in traction motor winding or traction generator also cause fire on loco. While taking over the loco, LP to observe traction motor inspection covers and traction generator cover for proper fitment and also ensure that no oil is available in the traction generator / alternator pit. 4. BKBL and high resistance Grids: Either by foreign body or loose contact of cables laid for BKBL and high resistance grid also causes fire on locomotive in the nose compartment. Crew to keep a watch while train is moving on dynamic brake for any smoke and smell and if such symptoms are noticed dynamic brake should not be used. 5. Burning of thermal insulator: The insulator burns due to overheating of compressed air in the discharge pipe line of compressor/expresser. 6. Any external burning element like asbestos lapping etc., may also lead to catch the fire on diesel locomotive. 7. Do not allow any cotton soaked waste, wool, etc., is loosely kept in the Engine Room which may contribute for catching fire. 8. Frequently check the loco axle boxes for overheating.