SUMMER INDUSTRIAL TRAININGA DISSERTATION (TRAINING REPORT)

Submitted in partial fulfilment of the requirement for theAward of Diploma in Mechanical Engineering

By MOHAMMAD SHAH FAHAD (12 DME 0935)Diploma in Mechanical Engineering

Under the Supervision ofMr. OMM KANT SHARMASSE/TRG, Diesel Training Centre

University PolytechnicJAMIA MILLIA ISLAMIA (NEW DELHI)2014

ACKNOWLEDGEMENT

I take this opportunity to express my sincere gratitude to the people who have helped me in the successful completion of my industrial training and the project. I would like to show my greatest appreciation to the highly devoted technical staff, supervisors and officials of the Diesel Locomotive Shed, Tughlakabad. I am highly indebted to them for their tremendous support and help during the completion of my training and project.

In particular, I am grateful to Mr Omm Kant Sharma, SSE/TRG (D.T.C.) of Diesel Locomotive Shed, Tughlakabad, who scheduled my training in the various departments and cells of the shed and handed out this project to me. I would like to thank all those people who directly or indirectly helped and guided me to complete our training and project in the Diesel Training Centre and various sections.

CERTIFICATE

This isto certify thatMr. _____________________________ pursuing Diploma in Mechanical Engineering fromJAMIA MILLIA ISLAMIA, New Delhi having roll number has donehis summer training at Diesel Loco Shed Tughlakabad, Delhi from____________to____________.The project work entitled ____________________________________, embodies the original work done by him at the end of hissummer training.

Mr. OMM KANT SHARMA(SSE/TRG, D.T.C., Diesel Loco Shed)Tughlakabad, Delhi

CONTENTS1. INDIAN RAILWAY

History of Indian railway 7 Development of steam locomotives 8 Classification of locomotives 9 Classification of syntaxes 10 Multiple unit trains 11-14 Companies engaged in manufacturing Locomotives (India) 15 Diesel loco shed Tughlakabad 16-18

2. DIESEL LOCOMOTIVES

Diesel electric locomotive 20-28 Diesel locomotive taking off steam 29Locomotives Diesel locomotives over electric 29-30Locomotive Fuel oil system 30-34 Lube oil system 35-36 Water cooling system 37-40

3. PROJECT- EXPRESSOR 41-51

4. GENERAL DISCIPLINE 525. SUGGESTIONS/FEEDBACK 52-53

HISTORY OF INDIAN RAILWAY The history of rail transport in India began in the mid-nineteenth century. Railways were first introduced to India in 1853 fromBombaytoThane. The Indian Railways, becoming one of the largest networks in the world. Indian Railways is the world'sninth largest commercial or utility employer, by number of employees, with over 1.4million employees.At the time of independence, 99% of locomotives in India were steam. At independence we decided to continue to invest in steam because coal was cheap and widely available. The alternatives, electric and diesel, both which were technologically vastly superior were expensive and required lots of investment, money and technological know how all of which we did not have. Ever since 1853, India ran on steam power with the only electric India faced massive shortage of locomotives at independence and to become self-sufficient in locomotives, Chittaranjan Locomotive works (CLW) was set up in 1949 itself for India to produce our own locomotives.CLW would first produce steam locos, then diesel and today, only electric and the Diesel Locomotive Works (DLW) of Varanasi was set up in 1963. Thanks to CLW, Indian Railways became self sufficient in locomotives pretty fast.Following a string of accidents and bad press, Indian Railways woke up and decided to do away with steam traction in favor of diesel/electric by the late 1950s. As a result, steam engine production was gradually wound down and the last WP (No. 7754) was produced in 1967 and the last WG (10480 Antim Sitara) was produced in 1970. The last steam locomotive to be produced in India was a Meter Gauge YG #3152 in 1972. Steam schedules were gradually as steam locomotives were pulled off the track and trains got dieselized. From around 2300 steamers in service in 1990, the number fell to 209 in 1995. The steam sun set on India on October 6 1995, whentheWL 15005 Sher-e-Punjabhauled last official Broad Gauge passenger steam service in India from Ferozepur to Jalandhar in Punjab, marking the end of an Indian summer. And in February 2000, the last surviving MG steam services in Gujarat were shut down. All steam locomotives had ceased to run in India, marking the end of an Indian summer. And in February 2000, the last surviving MG steam services in Gujarat were shut down. All steam locomotives had ceased to run in India.DEVELOPMENT OF STEAM LOCOMOTIVESThough invention of steam locomotives was a remarkable invention in vehicle industry, yet it had certain drawbacks. These conditions were ripe enough to give birth to diesel locomotives.A diesel locomotive generates energy to produce enough power to drive the electrical generator found within the engine. The generator powers the traction motors, and the traction motors are the engines that turn the locomotive's wheels. This series of one powerful piece supporting and driving another powerful piece produces an efficient way to propel the immense locomotive across the tracks, far more efficient than a steam engine. Each part of the diesel-electric motor serves its own purpose, and the diesel-electric locomotive generates and utilizes its own power to motion the train.As the technology behind the diesel engines advanced, B&O continued to run its trains on diesel-electric power. And as the technology evolved over the years, diesel-electric engines beefed up the power to lead heavier passenger and large freight trains across the country. Part of the reason the railroad companies stuck with diesel was its efficiency. Diesel-electric locomotives ran with less fueling than steam locomotives. This kept the trains moving on the tracks instead of having to stop frequently to "refuel" with water and oil. Diesel- electric locomotives also required less maintenance than steam-powered engines. This also kept the engines on the tracks, moving and making money, instead of "in the shop" costing money. Diesel-electric locomotive engines won the hearts of many a railroad company because they were more profitable than a steam- powered locomotive.

CLASSIFICATION OF LOCOMOTIVES In India, locomotives are classified according to their track gauge, motive power, the work they are suited for and their power or model number. The class name includes this information about the locomotive. It comprises 4 or 5 letters. The first letter denotes the track gauge. The second letter denotes their motive power (Diesel or Electric) and the third letter denotes the kind of traffic for which they are suited (goods, passenger, mixed or shunting). The fourth letter used to denote locomotives' chronological model number. However, from 2002 a new classification scheme has been adopted. Under this system, for newer diesel locomotives, the fourth letter will denote their horsepower range. Electric locomotives don't come under this scheme and even all diesel locos are not covered. For them this letter denotes their model number as usual.A locomotive may sometimes have a fifth letter in its name which generally denotes a technical variant or subclass or subtype. This fifth letter indicates some smaller variation in the basic model or series, perhaps different motors, or a different manufacturer. With the new scheme for classifying diesel locomotives (as mentioned above) the fifth item is a letter that further refines the horsepower indication in 100 hp increments: 'A' for 100 hp, 'B' for 200 hp, 'C' for 300 hp, etc.

THE CLASSIFICATION SYNTAXESThe first letter (gauge)W Indian broad gauge (the "W" Stands for Wide Gauge - 5 ft 6 in) Y metre gauge (the "Y" stands for Yard Gauge - 3 ft or 1000mm) Z narrow gauge(2 ft 6 in) N narrow gauge (toy gauge) (2 ft)The second letter (motive power)D Diesel C DC electric (can run under DC overhead line only) A AC electric (can run under AC overhead line only) CA both DC and AC (can run under both AC and DC overhead line); 'CA' is considered a single letter B Battery electric locomotive (rare)The third letter (job type)G Goods P passenger M mixed; both goods and passenger S shunting (also known as switching engines or switchers in the USA and some other countries) U electric multiple unit (used to carry commuters in city suburbs)R Railcars For example, in "WDM 3A":"W" means broad gauge "D" means diesel motive power "M" means suitable for both goods and passenger service "3A" means the locomotive's power is 3,100 hp ('3' stands for 3000 hp, 'A' denotes 100 hp more)Or, in "WAP 5":"W" means broad gauge "A" mean AC electric traction motive power "P" means suitable for Passenger service "5" denotes that this locomotive is chronologically the fifth electric locomotive model used by the railways for passenger service.

MULTIPLE UNIT TRAINS

DIESEL MULTIPLE UNIT Adiesel multiple unitorDMUis amultiple-unittrain powered by on-boarddiesel engines. A DMU requires no separatelocomotive, as the engines are incorporated into one or more of the carriages. They may also be referred to as arailcarorrailmotor, depending on country.

DesignThe diesel engine may be located above the frame in an engine bay or under the floor. Driving controls can be at both ends, on one end, or none.TypesDMUs are usually classified by the method of transmitting motive power to their wheels.

Diesel-mechanicalIn a diesel-mechanical multiple unit (DMMU) the rotating energy of the engine is transmitted via agearboxand driveshaft directly to the wheels of the train, like acar. The transmissions can be shifted manually by the driver, as in the great majority of first-generationBritish RailDMUs, but in most applications gears are changed automatically.

Diesel-hydraulicIn a diesel-hydraulic multiple unit, a hydraulictorque converter, a type of fluid coupling, acts as the transmission medium for the motive power of the diesel engine to turn the wheels. Some units feature a hybrid mix of hydraulic and mechanical transmissions, usually reverting to the latter at higher operating speeds as this decreases engine RPM and noise.

Diesel-electric In a diesel-electric multiple unit (DEMU) adiesel enginedrives anelectrical generatoror analternatorwhich produceselectrical energy. The generated current is then fed to electrictraction motorson thewheelsorbogiesin the same way as a conventionaldiesel electriclocomotive.[1]In modern DEMUs, such as theBombardier Voyager family, each car is entirely self-contained and has its own engine, generator and electric motors.[1]In older designs, such as theBritish Rail Class 207, some cars within theconsistmay be entirely unpowered or only feature electric motors, obtaining electrical current from other cars in the consist which have a generator and engine.

BenefitsA train composed of DMU cars scales well, as it allows extra passenger capacity to be added at the same time as motive power. It also permits passenger capacity to be matched to demand, and for trains to be split and joined en route. It is not necessary to match the power available to the size and weight of the train each unit is capable of moving itself, so as units are added, the power available to move the train increases by the necessary amount. DMUs may have better acceleration capabilities, with more power-driven axles, making them more suitable for routes with frequent closely spaced stops, as compared with conventional locomotive and unpowered carriage setups.Distribution of the propulsion among the cars also results in a system that is less vulnerable to single-point-of-failure outages. Many classes of DMU are capable of operating with faulty units still in the consist. Because of the self-contained nature of diesel engines, there is no need to runoverhead electric linesorelectrified track, which can result in lower system construction costs.These advantages must be weighed against the under floor noise and vibration that may be an issue with this type of train.

ELECTRICAL MULTIPLE UNITAnelectric multiple unitorEMUis amultiple unittrainconsisting of self-propelled carriages, usingelectricityas the motive power. An EMU requires no separatelocomotive, as electrictraction motorsare incorporated within one or a number of the carriages.EMUs are popular on commuter and suburban rail networks around the world due to their fast acceleration and pollution-free operation.[1]Being quieter thanDMUsandlocomotive-drawn trains, EMUs can operate later at night and more frequently without disturbing residents living near the railway lines.In addition, tunnel design for EMU trains is simpler as provisions do not need to be made for diesel exhaust fumes, although retrofitting existing tunnels to accommodate the extra equipment needed to transmit the power to the train can be expensive and difficult if the tunnel has limited clearance.

PUSH- PULL TRAINPushpullis a mode of operation forlocomotive-hauledtrainsallowing them to be driven from either end.A pushpull train has a locomotive at one end of the train, connected via some form of remote control, such asmultiple-unit train control, to a vehicle equipped with acontrol cabat the other end of the train. This second vehicle may be another locomotive, or an unpoweredcontrol car.

Companies engaged in manufacturing of locomotives (INDIA)Active Companies Bharat Heavy Electricals Limited Chittaranjan Locomotive Works Diesel Locomotive Works(DLW) Golden Rock Railway Workshop Bharat Earth Movers Limited SAN Locomotive & Engineering Co Ltd. Banglore. M/s Medha Servo Drives Pvt Ltd. Diesel-Loco Modernisation Works NRE National Railway Equipment

Defunct CompaniesTata Engineering and Locomotive Company(TELCO)

DIESEL LOCO SHED, (TUGHLAKABAD)

Indian railwaysis the secondlargestnetworkingthe world.Indian railways have a fleet of about 3800 BG Diesel locomotives Which are basedinabout 47maintenance sheds spread alloverthe country.

WHAT IS DIESEL SHED

Itisaplacewhererepairandmaintenanceofa diesel locomotives Iscarriedout soas toincreasesitslifeand efficiency and toreduce linefailures toa minimum extent.

DIESEL SHED ATTUGHLAKABAD, DELHI

TughlakabadisonesuchpremiershedinNorthernRailways homing 162Diesel Locos.Becauseofitsgeographical location,and being In the capital, it serves a large number of Mails /Expresstrains which across the length & breadth of thecountrycasting to goods operation.Diesel shed,Tughlakabad is spread over an area of1,10,000 m sq outofWhich10,858m sq is covered.DieselShed, Tughlakabad wasestablished in the year1970 with aplanned holdingof 75 locomotives and initial holding of26WDM2 locomotives. Today, after 40 years of its existence, the shed has grown to a total holding of 162 locomotives of five types, which include 59 WDM2 (2600HP), 21 WDM4 (3100HP), 02 WDM2 (3300HP), 51 WDP1 (2300HP) and 29 WDP3 (3100HP). Shed is maintaining a mail link of 122 locos, which is highest for any shed on Indian railways. Some of the prestigious trainsbeingrunbytheshed are:JammuTawiandGuhati Rajdhani express, Shatabdi express for Amritsar, Dehradun and Ajmer,PujaExpress,UttarSamparkkranti,LucknowMail, Kashivishwanath, Sharamjivi Express and the tourist train palace-on-wheels.

SHED LAYOUT &INFRASTRUCTURE

The shed has a total berthing capacity for 17 locomotives under 4 covered bays. The main bays are:-1. Thesubassembliessection2. The heavy repairandbogie section (3berthsforheavy repairs & 2 lifting points)3. Mail running repair bay (6 berths).4.Goodsandoutofcourserunningrepairbay(6berths)There is one old steam shed, which has recently been connected. This shed has a capacity for berthing 4 locomotives and is not equipped with lighting and overhead crane. This shed can hence be used for light repairs only.

DIESEL TRAINING CENTRE

Diesel training centre at Tughlakabad was set in 1975 in premises of diesel shed, Tughlakabad northern railway with a view to train diesel running staff as well as diesel maintenancetoimprove overallefficiencyofrailwayworkersqualitybyupgradingthe knowledge of railway workmen by starting few courses.

INFRASTUCTURE-DIESEL TRAINING CENTRE

There are five classrooms ,a big hall and a model room with cutmodels (with working and non-working types of various important components of locomotives such as expressor, cylinder head, turbo supercharger, water pump, lube oil pump, governor, etc for betterunderstanding. A well qualified team of trainers from maintenance and running is available for providing training.

DIESEL FAULT SIMULATOR

It comprises of actual electric panel, cut model of engine block(inworking) and test benches. It helps in improving, analyzing and understanding trouble-shooting knowledge of running staff as well as maintenance staff.

REGULAR COURSES

1. DieselAsstt.todieseldriverpromotion course2. DieselAsstt. Refresher course3. Dieselrefresher course

OTHER SPECIAL COURSES

1. Knowledge up gradation shot duration course forDsl. Tech. (Mech. & Elect)2. Electric traction to diesel traction conversion.3. Coursefor drivers, shutters &Asstt.Drivers.4. 3 yearsApprenticetech. (Dsl) (Mech. &Elect.)5. 6monthsApprenticeTech.(Dsl)(Mech RRB Batch).6. PreselectionscoachingofSC/STcandidatesforgroup B LDCE cadre.7. PreselectionscoachingofSC/STcandidatesofTechnicians for the post of JE-2. 8.Preselection coaching of SC/ST candidates of Dsl.Technicians for the post Asstt.Drivers.

LOCOS AT TUGHLAKABAD (TKD) DIESEL SHED1- WDM2 -2600HP2- WDP1 -2300HP3- WDP3A -3100HP4- WDM3A -3100HP5- WDM3C -3300HP

ORGANISATION AL STRUCTURE AND STAFF STRENGTHTughlakabad has a sanctioned strength 1313 against which 1210 persons are on roll. There 9 posts of officer in shed. The shed is headed by the Sr. DME who is assisted by 2 Sr. Scale & 6 Jr. Scale officers.The laboratories are looked after by an ACMT and the attached stores depot by an AMM. The training school and simulator have been entrusted to a separate Assistant Officer. These officer also report to the Sr. DME.

DIESEL LOCOMOTIVES

DIESEL-ELECTRIC LOCOMOTIVEThe modern diesel locomotive is a self contained version of the electric locomotive. Like the electric locomotive, it has electric drive, in the form of traction motors driving the axles and controlled with electronic controls. It also has many of the same auxiliary systems for cooling, lighting, heating, braking and hotel power (if required) for the train. It can operate over the same routes (usually) and can be operated by the same drivers. It differs principally in that it carries its own generating station around with it, instead of being connected to a remote generating station through overhead wires or a third rail. The generating station consists of a large diesel engine coupled to an alternator producing the necessary electricity. A fuel tank is also essential. It is interesting to note that the modern diesel locomotive produces about 35% of the power of a electric locomotive of similar weight.

Parts of a Diesel-Electric LocomotiveThe following diagram shows the main parts of a US-built diesel-electric locomotive.

Diesel EngineThis is the main power source for the locomotive. It comprises a large cylinder block, with the cylinders arranged in a straight line or in a V.The engine rotates the drive shaft at up to 1,000 rpm and this drives the various items needed to power the locomotive. As the transmission is electric, the engine is used as the power source for the electricity generator or alternator, as it is called nowadays.

Main AlternatorThe diesel engine drives the main alternator which provides the power to move the train. The alternator generates AC electricity which is used to provide power for the traction motors mounted on the trucks (bogies). In older locomotives, the alternator was a DC machine, called a generator. It produced direct current which was used to provide power for DC traction motors. Many of these machines are still in regular use. The next development was the replacement of the generator by the alternator but still using DC traction motors. The AC output is rectified to give the DC required for the motors. Auxiliary AlternatorLocomotives used to operate passenger trains are equipped with an auxiliary alternator. This provides AC power for lighting, heating, air conditioning, dining facilities etc. on the train. The output is transmitted along the train through an auxiliary power line. In the US, it is known as "head end power" or "hotel power". In the UK, air conditioned passenger coaches get what is called electric train supply (ETS) from the auxiliary alternator.Motor BlowerThe diesel engine also drives a motor blower. As its name suggests, the motor blower provides air which is blown over the traction motors to keep them cool during periods of heavy work. The blower is mounted inside the locomotive body but the motors are on the trucks, so the blower output is connected to each of the motors through flexible ducting. The blower output also cools the alternators. Some designs have separate blowers for the group of motors on each truck and others for the alternators. Whatever the arrangement, a modern locomotive has a complex air management system which monitors the temperature of the various rotating machines in the locomotive and adjusts the flow of air accordingly.Air IntakesThe air for cooling the locomotive's motors is drawn in from outside the locomotive. It has to be filtered to remove dust and other impurities and its flow regulated by temperature, both inside and outside the locomotive. The air management system has to take account of the wide range of temperatures from the possible +40C of summer to the possible -40C of winter.

Rectifiers/InvertersThe output from the main alternator is AC but it can be used in a locomotive with either DC or AC traction motors. DC motors were the traditional type used for many years but, in the last 10 years, AC motors have become standard for new locomotives. They are cheaper to build and cost less to maintain and, with electronic management can be very finely controlled. To convert the AC output from the main alternator to DC, rectifiers are required. If the motors are DC, the output from the rectifiers is used directly. If the motors are AC, the DC output from the rectifiers is converted to 3-phase AC for the traction motors.In the US, there are some variations in how the inverters are configured. GM EMD relies on one inverter per truck, while GE uses one inverter per axle - both systems have their merits. EMD's system links the axles within each truck in parallel, ensuring wheel slip control is maximised among the axles equally. Parallel control also means even wheel wear even between axles. However, if one inverter (i.e. one truck) fails then the unit is only able to produce 50 per cent of its tractive effort. One inverter per axle is more complicated, but the GE view is that individual axle control can provide the best tractive effort. If an inverter fails, the tractive effort for that axle is lost, but full tractive effort is still available through the other five inverters. By controlling each axle individually, keeping wheel diameters closely matched for optimum performance is no longer necessary.Electronic ControlsAlmost every part of the modern locomotive's equipment has some form of electronic control. These are usually collected in a control cubicle near the cab for easy access. The controls will usually include a maintenance management system of some sort which can be used to download data to a portable or hand-held computer.Control StandThis is the principal man-machine interface, known as a control desk in the UK or control stand in the US. The common US type of stand is positioned at an angle on the left side of the driving position and, it is said, is much preferred by drivers to the modern desk type of control layout usual in Europe and now being offered on some locomotives in the US. CabThe standard configuration of US-designed locomotives is to have a cab at one end of the locomotive only. Since most the US structure gauge is large enough to allow the locomotive to have a walkway on either side, there is enough visibility for the locomotive to be worked in reverse. However, it is normal for the locomotive to operate with the cab forwards. In the UK and many European countries, locomotives are full width to the structure gauge and cabs are therefore provided at both ends.

BatteriesJust like an automobile, the diesel engine needs a battery to start it and to provide electrical power for lights and controls when the engine is switched off and the alternator is not running.Traction MotorSince the diesel-electric locomotive uses electric transmission, traction motors are provided on the axles to give the final drive. These motors were traditionally DC but the development of modern power and control electronics has led to the introduction of 3-phase AC motors. There are between four and six motors on most diesel-electric locomotives. A modern AC motor with air blowing can provide up to 1,000 hp.Pinion/GearThe traction motor drives the axle through a reduction gear of a range between 3 to 1 (freight) and 4 to 1 (passenger).Fuel TankA diesel locomotive has to carry its own fuel around with it and there has to be enough for a reasonable length of trip. The fuel tank is normally under the loco frame and will have a capacity of say 1,000 imperial gallons (UK Class 59, 3,000 hp) or 5,000 US gallons in a General Electric AC4400CW 4,400 hp locomotive. The new AC6000s have 5,500 gallon tanks. In addition to fuel, the locomotive will carry around, typically about 300 US gallons of cooling water and 250 gallons of lubricating oil for the diesel engine.Air ReservoirsAir reservoirs containing compressed air at high pressure are required for the train braking and some other systems on the locomotive. These are often mounted next to the fuel tank under the floor of the locomotive. Air CompressorThe air compressor is required to provide a constant supply of compressed air for the locomotive and train brakes. In the US, it is standard practice to drive the compressor off the diesel engine drive shaft. In the UK, the compressor is usually electrically driven and can therefore be mounted anywhere. The Class 60 compressor is under the frame, whereas the Class 37 has the compressors in the nose.Drive ShaftThe main output from the diesel engine is transmitted by the drive shaft to the alternators at one end and the radiator fans and compressor at the other end.

Gear BoxThe radiator and its cooling fan is often located in the roof of the locomotive. Drive to the fan is therefore through a gearbox to change the direction of the drive upwards.Radiator and Radiator FanThe radiator works the same way as in an automobile. Water is distributed around the engine block to keep the temperature within the most efficient range for the engine. The water is cooled by passing it through a radiator blown by a fan driven by the diesel enginTurbo ChargingThe amount of power obtained from a cylinder in a diesel engine depends on how much fuel can be burnt in it. The amount of fuel which can be burnt depends on the amount of air available in the cylinder. So, if you can get more air into the cylinder, more fuel will be burnt and you will get more power out of your ignition. Turbo charging is used to increase the amount of air pushed into each cylinder. The turbocharger is driven by exhaust gas from the engine. This gas drives a fan which, in turn, drives a small compressor which pushes the additional air into the cylinder. Turbocharging gives a 50% increase in engine power.The main advantage of the turbocharger is that it gives more power with no increase in fuel costs because it uses exhaust gas as drive power. It does need additional maintenance, however, so there are some type of lower power locomotives which are built without it. Sand BoxLocomotives always carry sand to assist adhesion in bad rail conditions. Sand is not often provided on multiple unit trains because the adhesion requirements are lower and there are normally more driven axles.

THE WHEEL ON THE RAIL

Railway wheels sit on the rails without guidance except for the shape of the tyre in relation to the rail head. Contrary to popular belief, the flanges should not touch the rails. Flanges are only a last resort to prevent the wheels becoming derailed - they're a safety feature. The wheel tyre is coned and the rail head slightly curved as shown in the following diagram (Fig 1). The rails are also set at an inward angle.Ideally, the wheel profile should be determined by agreement between the railway infrastructure owner and the rolling stock owner. Of course, it varies from place to place but it is rarely a simple angle. It's usually a carefully calculated compound form. With respect to the rail angle, in the UK for example, it is set at 1 in 20 (1/20 or 0.05). In the US and France it's usually at 1/40. Light rail systems operating over roadways will have special profiles.

Fig 1: The shape and location of wheels and rails on straight track.

This diagram is exaggerated to show the principal of the wheel/rail interface on straight track. Note that the flanges do not normally touch the rails.On curved track, the outer wheel has a greater distance to travel than the inner wheel. To compensate for this, the wheelset moves sideways in relation to the track so that the larger tyre radius on the inner edge of the wheel is used on the outer rail of the curve, as shown in Fig 2.

Fig 2: The location of the wheels in relation to the rails on curved track.The inner wheel uses the outer edge of its tyre to reduce the travelled distance during the passage round the curve. The flange of the outer wheel will only touch the movement of the train round the curved rail is not in exact symmetry with the geometry of the track. This can occur due to incorrect speed or poor mechanical condition of the track or train. It often causes a squealing noise. It naturally causes wear.Many operators use flange or rail greasing to ease the passage of wheels on curves. Devices can be mounted on the track or the train. It is important to ensure that the amount of lubricant applied is exactly right. Too much will cause the tyre to become contaminated and will lead to skidding and flatted wheels. There will always be some slippage between the wheel and rail on curves but this will be minimised if the track and wheel are both constructed and maintained to the correct standards.

BOGIES (TRUCKS)

A pair of train wheels is rigidly fixed to an axle to form a wheelset. Normally, two wheelsets are mounted in a bogie, or truck as it is called in US English. Most bogies have rigid frames as shown below (Fig 3).

Fig 3: A standard rigid bogie on curved track.The bogie frame is turned into the curve by the leading wheelset as it is guided by the rails. However, there is a degree of slip and a lot of force required to allow the change of direction. The bogie is, after all, carrying about half the weight of the vehicle it supports. It is also guiding the vehicle, sometimes at high speed, into a curve against its natural tendency to travel in a straight line.Steerable BogiesTo overcome some of the mechanical problems of the rigid wheelset mounted in a rigid bogie frame, some modern designs incorporate a form of radial movement in the wheelset as shown below (Fig 4)

Fig 4: A bogie on curved track with radially steering wheel sets.In this example, the wheel set "floats" within the rigid bogie frame. The forces wearing the tyres and flanges are reduced as are the stresses on the bogie frame itself. There are some designs where the bogie frame is not rigid and the steering is through mechanical links between the leading and trailing wheel set.

DIESEL LOCOMOTIVES TAKING OFF STEAM LOCOMOTIVESDiesel-electric locomotives took off because experts and laypeople alike easily understood their mechanics. A diesel locomotive generates energy to produce enough power to drive the electrical generator found within the engine. The generator powers the traction motors, and the traction motors are the engines that turn the locomotive's wheels. This series of one powerful piece supporting and driving another powerful piece produces an efficient way to propel the immense locomotive across the tracks, far more efficient than a steam engine. Each part of the diesel-electric motor serves its own purpose, and the diesel-electric locomotive generates and utilizes its own power to motion the train.As the technology behind the diesel engines advanced, B&O continued to run its trains on diesel-electric power. And as the technology evolved over the years, diesel-electric engines beefed up the power to lead heavier passenger and large freight trains across the country. Part of the reason the railroad companies stuck with diesel was its efficiency. Diesel-electric locomotives ran with less fueling than steam locomotives. This kept the trains moving on the tracks instead of having to stop frequently to "refuel" with water and oil. Diesel- electric locomotives also required less maintenance than steam-powered engines. This also kept the engines on the tracks, moving and making money, instead of "in the shop" costing money. Diesel-electric locomotive engines won the hearts of many a railroad company because they were more profitable than a steam- powered locomotive.

DIESEL LOCOMOTIVES OVER ELECTRIC LOCOMOTIVES

Diesel Traction is the latestFirst steam locomotive Puffing Devil, built by Richard Trivethick, a Conish engineer in 1801.Electric Traction built by German engineer Werner Van Siemens in 1881.First Diesel loco came into existence in 1912 after invention of Diesel engine in 1893- Thus, beginning of Most Modern Diesel Traction.Diesel Traction is most energy efficientThermal efficiency of diesel engine is 40% and transmission losses reduce it to about 32%The efficiency of electric traction when electricity is generated from coal is only about 29% with 63% losses in Power Station, 4% in Transmission lines & 4% in locomotives.Diesel Locos haul heavier loadsOver the world Diesel locos haul trains up to 23,000 tonnes while there is no evidence of such capability in case of electric traction.

Diesel Traction is closest to NatureIn Diesel Traction both the production and use of power takes place on the locomotives itself whereas in case of electric traction, electricity is produced in the Power Plant and then used in Electric locomotives.A comparison made on the basis of pollution created on account of generation of 1 KW of power in power plant shows that the Electric Traction results in 65% more pollution than Diesel Traction. FUEL OIL SYSTEMAll locomotive units 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 fresh 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. The fuel oil system consists of two integrated systems. These are- FUEL FEED SYSTEM. FUEL INJECTION SYSTEM.FUEL FEED SYSTEM AND ITS ASSOCIATE COMPONENTS

The fuel feed system provides the back-up support to the fuel injection pumps by maintaining steady supply of fuel to them at the required pressure so that the fuel pump can meter and deliver the oil to the cylinder at correct pressure and time. The fuel feed system includes the following:- Fuel oil tankA fuel oil tank of required capacity (normally 5000ltrs), is fabricated under the superstructure of the locomotive and located in between the two bogies. Baffle walls are used inside it to arrest surge of oil when the locomotive is moving. A strainer filter at the filling plug, an indirect vent, drain plug, and glow rod type level indicators are also provided.Fuel primary filter A filter is provided on the suction side of the fuel transfer pump to allow only filtered oil into the pump. This enhances the working life of the fuel transfer pump. This filter is most often a renewable bleached cotton waste packed filter, commonly known as socks type filter element. These socks type filters are coarse filters and have a greater ability to absorb moisture, and are economical. However, in certain places, it has been replaced by paper type filter, which have longer service life.Fuel transfer pump or booster pumpThe fuel feed system has a transfer pump to lift the fuel from the tank. The gear type pump is driven by a dc motor, which is run by storage batteries through a suitable circuit. The pump capacity is 14 ltrs per minute at 1725 rpm at pressure 4 to 4.8 kg/cm. sq.Fuel relief valveThe spring- loaded relief valve is meant for by passing excess oil back to the fuel tank, thus releasing excess load on the pump and on the motor, to ensure their safety. It is adjusted to a required pressure (normally 5 kg/cm2), and it by- passes the excess fuel back to the oil tank. It also ensures the safety of the secondary filter and the pipe lines.Fuel secondary filterThe fuel secondary filter is located after the booster pump in the fuel feed system. The filter used is a paper type filter, cartridge of finer quality, renewable at regular intervals. This filter arrests the finer dirt particles left over by the primary filter and ensures longer life of the fuel injection equipments.Fuel regulating valveThe fuel-regulating valve is spring-loaded valve of similar design as the fuel relief valve. It is located after the secondary filter in the fuel feed system. This valve is adjusted to the required pressure (3 kg/cm2), and always maintains the same pressure in the fuel feed system by releasing the excess oil to the fuel oil tank. There is no by-passing of oil if the pressure is less than the adjusted level.

FUNCTIONING OF FUEL FEED SYSTEM The fuel booster pump or transfer pump is switched on and the pump starts sucking oil from the fuel oil tank, filtered through the primary filter. Because of variable consumption by the engine, the delivery pressure of the pump may rise increasing load on the pump and its drive motor. When the rate of consumption of the fuel by the engine is low, the relief valve ensures the safety of the components by releasing load, by- passing the excess pressure back to the tank. Then oil passes through the paper type secondary filter and proceeds to the right side fuel header. The fuel header is connected to eight numbers of fuel injection pumps on the right-bank of the engine, and a steady oil supply is maintained to the pumps at a pressure of 3 Kg./ sq. cm. Then the fuel oil passes on to the left side header and reaches eight fuel injection pumps on the left bank through jumper pipes. The regulating valve remaining after the left side fuel header, takes care of excess pressure over 3 Kg/cm Square by passing the extra oil back to the tank. A gauge connection is taken from here leading to the driver's cabin for indicating the fuel oil feed pressure. Thus the fuel feed system keeps fuel continuously available to the fuel injection pumps, which the pumps may use or refuse depending on the demand of the engine.

FUEL INJECTION SYSTEMWhen diesel engine is started, all fuel injection pumps start functioning. According to firing order all F.I. pumps start discharging fuel oil at high pressure to there respective nozzles through high pressure line tube. Fuel injection nozzle injects fuel oil to combustion chamber at 4000 psi. The internal function of F.I. pump and nozzle are described below.

1. 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 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.

FUEL INJECTION NOZZLEThe 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.

LUBE OIL SYSTEMThe lubricating system in a diesel engine is of vital importance. The lubricating oil provides a film of soft slippery oil in between two frictional surfaces to reduce friction and wear. It also serves the following purposes.1. Cooling of bearing, pistons etc.2. Protection of metal surfaces from corrosion, rust, surface damages and wears.3. Keep the components clean and free from carbon, lacquer deposits and prevent damage due to deposits.The importance of lube oil system is comparable to the blood circulation system in the human body. Safety of the engine, its components, and their life span will largely depend upon the correct quality of oil in correct quantity and pressure to various location of diesel engine.

LUBE OIL SYSTEM OF LOCO

The diesel engine of WDM2 class locomotives has full flow filtration lube oil system with bypass protection. The system essentially consists of the following components.1. Gear type lube oil pump driven by the engine crankshaft.2. Spring loaded relief valve, adjusted to 7.5 kg/cm2.3. Lube oil filter tank accommodating eight nos. of filter elements.4. Differential bypass valve set at 1.4 kg/cm2 differential pressure across the filter tank.5. Lube oil cooler, which has a bunch of element tubes through which cooling water circulates and circulation of lube oil takes place around the tubes.6. Regulating valve, which is a spring loaded valve adjusted to 4kg/cm2.7. Lube oil strainer, which is a wire mesh type filter reusable after cleaning.8. Oil pressure switch (OPS), which is meant to automatically shut down the engine in case of a drop in lube oil pressure below 1.3 kg/cm2.9. Oil pressure gauge, which indicates the main oil header pressure. 10. Oil sump having capacity 1260 lt. RR606 multigrade oil. The lube oil pump on the free end of the engine is driven by the engine crankshaft through suitable gears and keeps it running along with the engine. When the engine is started the pump draws oil from the engine oil sump and delivers it. The delivery pressure of the pump has to be controlled as the pump is driven by an engine of variable speed and would often have higher delivery pressure or load on it than actually required. This would mean loss of more power from the engine for driving the pump. Higher pressure may also endanger the safety of the filters and the pipelines and its joints. The relief valve releases the delivery pressure above its setting and bypasses it back to the oil sump. Oil then flows to a filter tank containing eight nos. of paper type filter elements. The filter has a bypass valve across it set a differential pressure of 1.4 kg/cm2. Due to the choking of the filter elements, if the pressure differential between the inlet and the outlet of the tank is more than 1.4 kg/cm2, then the differential bypass valve opens up to bypass a part of oil without filtration, and thus reduces the pressure on the filters. Although allowing unfiltered oil into the engine is not advisable, but there is another filter at later stage through which oil has to pass before entering the engine. Moreover, higher pressure on the filters may cause damage to the filters, and cause greater damage to the engines. After the filtration, the oil passes to the coolers, gets cooled by transferring heat to water, and regains its lost viscosity. At he discharge side of the cooler, a regulating valve adjusted at 4 kg/cm2 is provided to regulate the pressure. Excess pressure is regulated by passing the oil back to the engine oil sump. The oil then finds its way to the main oil header after another stage of filtration in the strainer type filter from which it is distributed for lubrication to different places as required. Direct individual connections are taken from the main oil header to all the main bearings. Oil thus passes through the main bearings supporting the crankshaft on the engine block, passes through the crank pin to lubricate the connecting rod big end bearing and the crank pin journals. It reaches the small end through rifle drilled hole and after lubricating the gudgeon pin and bearings enters into the pistons. The Aluminium alloy pistons are provide with spiral oil passage inside them for internal circulation of lube oil. This is done with the purpose of cooling the pistons, which are highly thermally loaded components. After circulation through the pistons, the oil returns back to the oil sump, but in this process, a part of the oil hits the running connecting rod and splashes on the cylinder liners for their lubrication. The actual lube oil pressure is a function of lube oil pump, temperature of oil, engine speed and regulating valve setting. A line from the main oil header is connected to a gauge in the driver's cabin to indicate the pressure level. If lube oil pressure drops to less than 1.3 kg/cm2, engine will automatically shut down through a safety device (OPS) to protect it from damage due to insufficient lubrication. From the main oil header, two branch lines are taken to the right and left side secondary headers to lubricate the components on both banks of the V shape engine. Each branch line of the secondary header lubricates the camshaft bearings, fuel pump lifters, valve lever mechanisms, and spray oil to lubricate the gears for camshaft drive. A separate connection is taken to the turbo super charger from the right side header for lubrication of its bearings. After circulation to all the points of lubrication, the oil returns back to the sump for recirculation through the same circuit.

Problems in lube oil system There are four factors, which effect the lube oil system pressure directly that is lube oil pump discharge capacity, diesel engine temperature, pressure setting value of Relief & Regulating valve and quality of lube oil. Some other factors like choking of filters / strainer, low oil level in c/case, contaminated lube oil, low idling speed and excessive wear/ clearance in bearings also effect the system pressure. During running of diesel engine it is observed that lube oil contaminated with water and oil level in c/case is increasing, which indicates water leakage inside the c/case. The sources are leakage of cylinder liner bottom gasket & sleeve, cracked cylinder liner, cracked cylinder head etc. Sometimes it is observed that lube oil contaminated with fuel oil, which indicates nozzles dribbling or fuel leak off gallery cracked. It is also observed that some engines consume high rate of lube oil, which indicates clearance between valve and valve guide is more, engine piston rings worn out or turbo oil seal damaged.

WATER COOLING SYSTEMAfter combustion of fuel in the engine, about 25-30 % of heat produced inside the cylinder is absorbed by the components surrounding the combustion chamber like piston, cylinder, cylinder head etc. Unless the heat is taken away from them and dispersed elsewhere, the components are likely to fail under thermal stresses. All internal combustion engines are provided with a cooling system designed to cool the excessively hot components, distribute the heat to the other surrounding components to maintain uniform temperature throughout the engine, and finally dissipate the excess heat to atmosphere to keep the engine temperature within suitable limits. Different cooling systems, like air cooling, water cooling are adopted, depending on the engine design, working conditions and service etc.. The advantage of having a water cooling system is that it maintains a uniform level of temperature throughout the engine and by controlling the water temperature, the engine temperature can be controlled effectively.

COOLING WATER AND ITS TREATMENTAlthough natural water can meet the basic requirement, its use is prohibited for the cooling of the engine because it contains many dissolved solids and corrosive elements. Some of the dissolved solids may form scales on the heat exchanger surface and reduce the heat transfer coefficient. It also accelerates corrosion. Other minerals get collected in the form off sludge at an elevated temperature. This sludge may get deposited at the low-pressure zone and choke the passage of circulation. The insulation caused by the scale deposits results in unequal expansion and localized stress, which may eventually rupture the engine block, cylinder block, cylinder heads etc. to eliminate all of these, distilled or de-mineralized water is used in the cooling system of the diesel locomotive.The water sample is tested for chromate concentration, hardness, pH value, and chloride content. In case Chromate concentration is found lower than the required quantity, mixture is added. Water is changed if hardness and chloride is higher than the recommended limit. Water is also changed if found contaminated with oil etc.When water is changed due to contamination etc. the system is cleaned by adding Tri-Sodium Phosphate, and circulating water for 45min, this water is drained out, and fresh distilled water with chromate mixture is filled in the locomotive.

COOLING WATER CIRCULATION

The WDM2 class locomotives have a closed circuit non-pressurised water cooling system for the engine. The system is filled in by 1210 ltrs. Of distilled water or demineralised water treated with non chromate corrosion inhibitor (Borate nitrite treatment) to maintain a concentration of 4000 PPM. The pH value is '8.5-9.5'. The water circuit has two storage tanks in two segments known as expansion tanks on top of the locomotive. Apart from supplementing in case of shortage in the system, these interconnected tanks have some empty space left at the top to provide expansion to the water when it is hot. A centrifugal pump driven by the engine crankshaft through a gear sucks water from the system and delivers it through outlet under pressure. The outlet of the pump has three branch lines from a three-way elbow. The branching off leads water to the different places as follows-1. To the turbo-supercharger through a flexible pipe to cool the intermediate casing, bearings on both sides of the rotor and the turbine casing. After cooling the components in the turbo-supercharger, water return to the inlet side of the pump through a bubble collector. The bubble collector with a vent line is a means to collect air bubbles formed due to evaporation and pass it onto the expansion tank, so that thy cannot cause air lock in the water circulatory system.2. The second line leads to the left bank of the cylinder block and water enter the engine block and circulates around the cylinder liners, cylinder heads on the left bank of the engine, and then passes onto the water outlet header. Individual inlet connections with water jumper pipes and outlet water riser pipes are provided to each cylinder head for entry and outlet of water from cylinder head to the water outlet header. Cooling of cylinder liners, piston rings, cylinder heads, valves, and fuel injection nozzles are done in this process. Water then proceeds the left side radiator for circulation through it, and releases its heat into the atmosphere to cool itself down before recirculation through the engine once again.3. The third connection from the three-way elbow leads to the right side of the cylinder block. After cooling the cylinder liners, heads etc. on the Right Bank the water reaches the right side radiator for cooling itself. Before it enters the radiator, a connection is taken to the water temperature manifold where a thermometer is fitted to indicate the water temperature. Four other temperature switches are also provided here, out of which T1 is for starting the movement of radiator fan at 60O C slowly through the eddy current clutch. The second switch T2 picks up at a water temperature of 64O C and accelerates the radiator fan to full speed. The third switch is the ETS3 (Engine Temperature Switch),set at 90 degree Celsius protection against hot engine, which gives bell alarm and red lamp indication. The fourth switch is ETS4 (set at 95 degree Celsius) which brings the engine back to the idling speed and power cut-off also takes place to reduce load on the engine. In this situation the GF switch is cut off and engine is notched up to full notch. It helps in bringing down the cooling water temperature quickly with the radiator fan moving at full speed. Water temperature is controlled by controlling the movement of the radiator fan. Cooling water from the left side radiator passes through the lube oil cooler, where water circulates inside a bunch of element tubes and lube oil circulates around the tubes. Thus passing through the lube oil cooler and cooling the lube oil, it unites with the suction pipe for recirculation through the cooling circuit. Cooling water from right side radiator passes through after cooler, where water circulates inside a bunch of element tubes and cooling the charge air, it unites with the suction pipe for recirculation.Apart from hot engine protection, another safety is also provided by way of low water switch (LWS). In the event of cooling water level falling below one inch from the bottom of the tank, the LWS shuts down the engine through the governor with warning bell and alarm indication to ensure the safety of the engine. Vent lines are provided from the after cooler, lube oil cooler, radiators. Turbo-supercharger vent box and bubble collectors etc. are provided to maintain uninterrupted circulation of cooling water by eliminating the hazards of air locks in the system.Cooling water is subjected to laboratory tests at regular intervals for quality controls. Contamination, chloride contents, and hardness etc.. are checked to reduce corrosion and scaling. The concentration of anti-corrosive mixture is also checked and laboratory advises corrective action in case of contamination. Proper quality control of cooling water and use of proper quantity of non chromate corrosion inhivitor prevents scaling and corrosion in the system, and ensures longer life of the components. Normally 8.2kg is added for new water in WDM2 locomotive.

MODIFICATIONS PERTAINING TO COOLING WATER SYSTEM OF WDM2 LOOMOTIVELouvred fin radiator: - The radiator core has been redesigned by providing louvred fins thereby increasing the cooling capacity by 14% due to improved air flow pattern through the radiator. High efficiency turbochargers: - High efficiency turbocharger has been provided on the fuel efficient version of wdm2 locos. This has resulted in lowering of the exhaust gas temperature by around 15% with modified after cooler. Large after cooler & water connection: - Large after cooler & water connection has been provided on the fuel efficient locos. This has reduced the heat input to the cooling system.Revision of ETS setting: - The setting of ETS3 is raised to 90 deg.C from 85 deg.C in order to avoid frequent hot engine alarms. Subsequently, with the introduction of pressurised cooling water system, one more ETS is added with the idea of providing only hot engine alarm through ETS3 at 90 deg. C and bringing the engine to idle by ETS4 at 95 deg. C. This change not only reduces the occurrences of hot engine alarm but also increases the heat transfer potential of the radiator at high temperature. Revised setting of OPS:- The setting of low lube oil pressure switch on WDM2 locos used to be 1.8 kg/ cm2 with a view to obviate the problem of engine shutting down due to operation of OPS while suddenly easing throttle from higher notches to idle, particularly during summer season, the OPS setting has been revised to 1.3 kg/ cm2. Pressurisation of cooling water system: - The cooling water circuit has been pressurised upto 7 psi thereby increasing the boiling point by 11 deg. C. This has not only increased the margin before the cooling water gets converted to steam but has also increased the temperature differential across the radiators at peak engine temperature, thereby increasing the rate of cooling in radiators. This has been achieved by providing a pressure cap assembly on the water tank.Flexible water inlet elbow: - Rubber hose type flexible water inlet elbow has been developed in place of the rigid one piece metallic water inlet elbow for obtaining better leak proofness even in face of misalignments between the engine block and the cylinder head. Digital water temperature indicator cum switch: - This has been developed to replace the existing water temperature gauge as well as the four engine temperature switches whose performance was quite unreliable. This aims at ensuring operation of radiator fan and alarm at proper temperature.Electronic water level indicator cum switch: - This has been developed to replace the existing water level gauge as well as the low water switch. This indicator shall give precise and reliable information regarding the water level to the driver in the cab itself. Improved type pipe joints: - This has been improved to replace the existing pipe joints viz. dressers Victaulic by superior rubber hoses along with double wire stainless steel clamps and by stainless steel bellows.

EXPRESSOR-COMPRESSOR IN LOCOMOTIVESA DISSERTATION ( PROJECT REPORT)

By MOHAMMAD SHAH FAHAD (12 DME 0935)Diploma in Mechanical Engineering

Under the Supervision ofMr. OMM KANT SHARMASSE/TRG, Diesel Training Centre

University PolytechnicJAMIA MILLIA ISLAMIA (NEW DELHI)2014

EXPRESSOR

(6 CD, 4 UC COMPRESSOR EXHAUSTER)

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 22" 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 splined flexible coupling (Kopper's coupling). Naturally the expressor crank shaft has eight speeds like the engine crank shaft and runs between 400 RPM to 1000 RPM range.

CONSTRUCTION AND DESCRIPTION

The expressor consists of the following components mainly;

(1) Crank case (2) Crank shaft (3) Four Nos. of exhauster cylinders with cylinder heads (4) One low pressure compressor cylinder with cylinder head (5) One high pressure cylinder with cylinder head (6) Six nos. of pistons with connecting rods (including one LP, one HP and four exhauster). (7) Lube oil pump.

Each of two crank journals supports three connecting rods. The crankshaft is supported at the both ends by double row ball bearings. Outside the ball bearings are located oil seals to prevent the leakage of oil from inside the crank case and air from outside into it.

The specific features and data are given below:-

Details Compressor (LP) Compressor (HP) Exhauster

1. No. of cylinders 1 1 4

2. Cylinder bore 7.750" 4.250" 7.250"

3. Stroke 5.625" 5.625" 5.265"

4. Piston rings 2+2 2+2 2+2 (Comp.& oil scrapper)

5. Normal working pressure - 140 PSI or 10 Kg/cm.sq.

6. Rated speed - 1000 RPM

7. Compressor displacement - 153.5 CFM / 4350 LPM at rated speed. 61.4 CFM / 17400 LPM at rated speed.

8. Exhauster displacement - 614 CFM / 17400 LPM at rated speed. 246 CFM / 6960 LPM at idling.

9. H.P consumed - 115 H.P max.

10. Lube oil pressure - 25 PSI to 60 PSI.

11. Oil sump capacity - 21 Lts.

12. Weight in assembled condition - 982 Kg.

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.

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. Working of the inlet and exhaust valves is 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 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 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 below the loco superstructure.

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 compressor 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 un-loader 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 relieved 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 un-loader plunger in conjunction with the air governor.

NS - 16 AIR GOVERNOR

The function of the air governor is to transmit main air reservoir pressure to the top of un-loader 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 un-loader valve is vented out. This action keep the suction valve open when loading of MR is not required anymore and again allow the compressor to work normally for loading when needed.

The NS-16 air governor consists of governor 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/sq.cm, 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 un-loader 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/sq.cm but remains above 8kg/sq.cm, 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/sq.cm to 8kg/sq.cm and the amount of air passing through the cut in tail valve keeps on supplying air to the un-loader valve top.

As soon as the MR pressure drops to 8kg/sq.cm, 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 un-loader. 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 separate system independent of the lube oil system of the engine. Lubricating oil of SAE 30 or SAE 40 grade is filled in the sump of 21 litres capacity. A gear type pumps under hung from the crank- shaft journal and is driven through sprocket and chain. The sump oil is sucked through a strainer filter screen by the pump and then circulates the same to the journal bearings at a pressure between 45psi to 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 flexible 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 separation and shaft separation, as mentioned above, the distance 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, horizontal 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" radius. The back -lash measurement is also done with the help of a dial indicator while moving the sleeve by hand.

DISTRIBUTION OF COMPRESSED AIR

Once compressed, the air has to be distributed around the locomotive and along the train. Normally, for a freight train, the air is only needed for control of the braking system and a "brake pipe" is run the length of the train to achieve this. The details are in the Railway Technical Web PagesNorth American Freight Train Brakes Page. For locomotive hauled passenger trains too, a brake pipe is normally sufficient but for multiple unit trains, a compressed air supply is usually provided on every car.

Compressed air distribution along a multiple unit train (see the drawing left) is by way of a "main reservoir pipe" (MR pipe), sometimes called a "main line pipe". The pipe is usually connected between cars by hoses. Each vehicle carries half the hose and is connected to the next car's hose by a cast steel coupling head which is designed to fit its opposite number. The heads will automatically disengage if they are forced apart by the sudden uncoupling of the train. They do this because, when the hoses become horizontal as the cars part, the heads reach a position where they uncouple.Most of the standard equipment is listed in the drawing above but most EMU trains use air pressure to raise the pantograph (if fitted) and some third rail trains use air pressure for control of shoe contact with the current rail.Angle CocksMost EMU vehicles have a MR pipe "angle cock" at each end. The angle cock can be closed to shut off the air supply at that point. Before uncoupling a vehicle, it is normal to close the angle cock on either side of the uncoupling position. This prevents any kick from the pipe as it is disengaged. Closing the angle cocks also has the effect of bleeding off the air trapped in the hose. The angle cock has a special bleed hole for this purpose.

APPLICATIONS OF COMPRESSED AIR IN LOCOMOTIVESAutomatic CouplersMany EMU's are provided with automatic couplers, usually at the ends of the unit. The coupler provides for all electrical, mechanical and pneumatic connections and is usually remotely operated from the driver's cab, or at least, inside the car. In the case of the MR pipe connection, a valve will open to provide the connection to the next unit once the cars are confirmed as coupled.Sometimes, automatic couplers are operated by a compressed air supply. This is used to provide power to engage and disengage the mechanical coupling and to open and close the connecting valves and contacts.Air Operated EquipmentApart from automatic couplers and brakes, already mentioned above, there are a number of items on a train which can use compressed air for operation, although the modern trend is away from air in favour of electric systems. There are some simple items like the horn and the windscreen wiper and some more complex ones like traction control and door operation. Each item will have its own isolating cock to allow for maintenance and most of the larger systems have their own storage reservoir.Many systems do not need the full main reservoir air pressure of 6 to 7 bar (120 to 140 lbs./in), so they are equipped with reducing valves on the upstream side of the reservoir. Some are equipped with gauges as well, although most engineers prefer just a test plug. Gauges stick out and get knocked off too easily. Nothing drains a reservoir more quickly than a broken gauge.Traction EquipmentAlthough electrical operation of traction control equipment is the most common, some traction control systems use compressed air to operate circuit breakers, contractors or camshafts. There is normally a traction control reservoir and its associated isolating cock provided for each vehicle set of equipment.DoorsMany rapid transit and suburban trains still use air operated door systems, controlled from the cab at one end of the train but using air stored in reservoirs on each car. The reservoirs are replenished automatically by way of their connection to the main reservoir pipe. Door systems usually use lower than normal MR air pressure. However, electric operators are the preferred option these days.Air SuspensionPlacing the car body on air pressure springs instead of the traditional steel springs has become common over the last 20 years for passenger vehicles. The air spring gives a better ride and the pressure can be adjusted automatically to compensate for additions or reductions in passenger loads. The changes in air pressure are used to give the brake and acceleration equipment the data needed to allow a constant rate according to the load on the vehicle.Driver's Brake ControlMost trains use compressed air for brake operation. Most locomotives and older EMU's use a pneumatic brake control system which requires a brake valve to be operated by the driver. The valve controls the flow of air into and out of the brake pipe which, in turn, controls the brakes on each vehicle in the train consist. The driver's brake valve is connected to the MR pipe in the cab so that there is always a constant supply of air available to replenish the brake control system when required. An isolating cock is provided in the cab so that the brake control can be closed off when the cab is not in use.Pantograph CompressorOne additional compressor is often provided on units which have air operated pantographs, i.e. those which are raised or lowered using compressed air as the power medium. Opening up a completely dead locomotive is only possible if there is battery power and some compressed air available to get the pantograph up to the overhead power supply. After all, nothing will work on the loco without power. So, a small, battery powered compressor is provided to give sufficient compressed air to raise the pantograph. As soon as the pan is up, full power is available to operate the main compressor.Wind Screen WipersWhistle/Horn Blowers

SUMMARY

The expressor is located at the free end of the engine bloke and driven through the extension shaft attached to the engine crank -shaft. 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 upto 10kg/cm2. Atmospheric 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 valves and delivery pipe. The HP cylinder compresses the air at high pressure and discharges it in main reservoir of locomotive for the use of brake system. There are a number of items on a train which can use compressed air for operation, although the modern trend is away from air in favour of electric systems. There are some simple items like the horn and the windscreen wiper and some more complex ones like traction control and door operation. Each item will have its own isolating cock to allow for maintenance and most of the larger systems have their own storage reservoir.

GENERAL DISCIPLINE

Parameters influencing performance of the diesel shed are as follows:Outage or Target (target isfixed by Railway board) If more, then outage = +ve If less, then outage = -ve 2) Total number of failure/ Total number ofsetouts 3) Reliability of locos (between Periodicity, it should not fail) 4) Punctuality (if 3 trains get late due tofailure of loco) 5) Lube oil Consumption (Average) 6) Specific Fuel Consumption 7) Environment and health ofemployee 8) Number of employees available in diesel shed 9) Infrastructure ofshed 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 ofthe shed.

SUGGESTIONS/FEEDBACK

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. 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 ofany 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 orover tightened.If budgetis notan issue we would like theshed touse 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 toarc welding, thereby resulting instronger welds.3) Whenever the measuring instruments are replaced, they are replaced with digital measuring instruments, so thatmeasuring 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 workbeing 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.

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.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 audiometric test every year.3) The cleanliness of the canteen needs tobe increased.4) All workers should be provided with gloves for handling hazardous chemicals and sharp objects.They shouldalso beprovided with safetyglasses.5) The qu