Ratlam Diesel Shed Training Report

RISHIRAJ INSTITUTE OF TECHNOLOGY INDORE

A INDUSTRIAL TRAINING REPORT ON

DIESEL LOCOMOTIVE OF BROAD GAUGE CLASS SUBMITTED TO

RAJIV GANDHI PROUDYOGIKI VISHWAVIDYALAYA FOR PARTIAL FULFILLMENT OF THE AWARD OF THE DEGREE OF

BACHELOR OF ENGINEERING IN MECHANICAL ENGINEERING SESSION 2011-2012

SUBMITTED BY:

SUBMITTED TO:

MANOJ PANCHAL (0817ME081026)

Mr. P.K. SAHU

ABHISHEK TIWARI (0817ME081001)

ACKNOWLEDGEMENT A WORK IS INCOMPLETED WITHOUT PROPER GUIDANCE OF MENTOR. I HAVE BEEN LUCKILY TO BE BLESSED WITH THE HELP OF SUCH A PERSON AND DEPARTMENT. FIRST AND MOST I WOULD LIKE TO THANKS INDIAN RAILWAY THAT THEY PROVIDED US THE OPPORTUNITY TO UNDERGO INDUSTRIAL TRAINING FROM THEIR RATLAM TRACTION TRAINING CENTRE .IT IS ONE OF THE MAINTENANCE CENTRE OF BROAD GUAGE CLASS LOCOMOTIVES. I WOULD ALSO LIKE TO THANKS THE PRINCIPAL Mr. R. UPADHYAY OF DIESEL TRACTION TRAINING CENTRE RATLAM DIESEL SHED (WESTERN RAILWAY). HE GUIDED US THROUGH OUT TRAINING PROGRAM SO THAT WE CAN GET FULL ADVANTAGE OF IT.

CONTENT TOPIC NAME 1. INTRODUCTION.. 2. PARTS OF DIESEL ELECTRIC LOCO. 3. CLASSIFICATION OF LOCOS. 4. BREAKING OF LOCOS. 5. MAINTENANCE OF BROAD GUAGE CLASS DIESEL LOCOS.

PAGE NO.

INTRODUCTION: The Diesel Locomotive The 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.

The Diesel Engine The diesel engine was first patented by Dr Rudolf Diesel (1858-1913) in Germany in 1892 and he actually got a successful engine working by 1897. By 1913, when he died, his engine was in use on locomotives and he had set up a facility with Sulzer in Switzerland to manufacture them. His death was mysterious in that he simply disappeared from a ship taking him to London. The diesel engine is a compression-ignition engine, as opposed to the petrol (or gasoline) engine, which is a spark-ignition engine. The spark ignition engine uses an electrical spark from a "spark plug" to ignite the fuel in the engine's cylinders, whereas the fuel in the diesel engine's cylinders is ignited by the heat caused by air being suddenly compressed in the cylinder. At this stage, the air gets compressed into an area 1/25th of its original volume. This would be expressed as a compression ratio of 25 to 1. A compression ratio of 16 to 1 will give an air pressure of 500 lbs/in² (35.5 bar) and will increase the air temperature to over 800°F (427°C). The advantage of the diesel engine over the petrol engine is that it has a higher thermal capacity (it gets more work out of the fuel), the fuel is cheaper because it is less refined than petrol and it can do heavy work under extended periods of overload. It can however, in a high speed form, be sensitive to maintenance and noisy, which is why it is still not popular for passenger automobiles.

Parts of a Diesel-Electric Locomotive The following diagram shows the main parts of a US-built diesel-electric locomotive. Click on the part name for a description.

Diesel Engine This 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 Alternator The diesel engine drives the main alternator which provides the power to move the train. The alternator generates AC electricity which is used to provide power for the traction motors mounted on the trucks (bogies). In older locomotives, the alternator was a DC machine, called a generator. It produced direct current which was used to provide power for DC traction motors. Many of these machines are still in regular use. The next development was the replacement of the generator by the alternator but still using DC traction motors. The AC output is rectified to give the DC required for the motors. For more details on AC and DC traction.

Auxiliary Alternator Locomotives 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 Blower The diesel engine also drives a motor blower. As its name suggests, the motor blower provides air which is blown over the traction motors to keep them cool during 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 Intakes The 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 +40°C of summer to the possible -40°C of winter.

Rectifiers/Inverters The output from the main alternator is AC but it can be used in a locomotive with either DC or AC traction motors. DC motors were the traditional type used for many years but, in the last 10 years, AC motors have become standard for new locomotives. They are cheaper to build and cost less to maintain and, with electronic management can be very finely controlled. To 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 Controls Almost every part of the modern locomotive's equipment has some form of electronic control. These are usually collected in a control cubicle near the cab for easy access. The controls will usually include a maintenance management system of some sort which can be used to download data to a portable or hand-held computer.

Control Stand This is the principal man-machine interface, known as a control desk in the UK or control stand in the US. The common US type of stand is positioned at an angle on the left side of the driving position and, it is said, is much preferred by drivers to the modern desk type of control layout usual in Europe and now being offered on some locomotives in the US.

Cab The 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.

Batteries Just like an automobile, the diesel engine needs a battery to start it and to provide electrical power for lights and controls when the engine is switched off and the alternator is not running.

Traction Motor Since the diesel-electric locomotive uses electric transmission, traction motors are provided on the axles to give the final drive. These motors were traditionally DC but the development of modern power and control electronics has led to the introduction of 3-phase AC motors. There are between four and six motors on most diesel-electric locomotives. A modern AC motor with air blowing can provide up to 1,000 hp.

Pinion/Gear The traction motor drives the axle through a reduction gear of a range between 3 to 1 (freight) and 4 to 1 (passenger).

Fuel Tank A diesel locomotive has to carry its own fuel around with it and there has to be enough for a reasonable length of trip. The fuel tank is normally under the loco frame and will have a capacity of say 1,000 imperial gallons (UK Class 59, 3,000 hp) or 5,000 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 Reservoirs Air 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 Compressor The air compressor is required to provide a constant supply of compressed air for the locomotive and train brakes. In the US, it is standard practice to drive the compressor off the diesel engine drive shaft. In the UK, the compressor is usually electrically driven and can therefore be mounted anywhere. The Class 60 compressor is under the frame, whereas the Class 37 has the compressors in the nose.

Drive Shaft The 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 Box The radiator and its cooling fan is often located in the roof of the locomotive. Drive to the fan is therefore through a gearbox to change the direction of the drive upwards.

Radiator and Radiator Fan The 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 engine.

Turbo Charging The 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 Box Locomotives 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.

Mechanical Transmission A diesel-mechanical locomotive is the simplest type of diesel locomotive. As the name suggests, a mechanical transmission on a diesel locomotive consists a direct mechanical link between the diesel engine and the wheels. In the example below, the diesel engine is in the 350-500 hp range and the transmission is similar to that of an automobile with a four speed gearbox. Most of the parts are similar to the diesel-electric locomotive but there are some variations in design mentioned below.

Fluid Coupling In a diesel-mechanical transmission, the main drive shaft is coupled to the engine by a fluid coupling. This is a hydraulic clutch, consisting of a case filled with oil, a rotating disc with curved blades driven by the engine and another connected to the road wheels. As the engine turns the fan, the oil is driven by one disc towards the other. This turns under the force of the oil and thus turns the drive shaft. Of course, the start up is gradual until the fan speed is almost matched by the blades. The whole system acts like an automatic clutch to allow a graduated start for the locomotive.

Gearbox This does the same job as that on an automobile. It varies the gear ratio between the engine and the road wheels so that the appropriate level of power can be applied to the wheels. Gear change is manual. There is no need for a separate clutch because the functions of a clutch are already provided in the fluid coupling.

Final Drive The diesel-mechanical locomotive uses a final drive similar to that of a steam engine. The wheels are coupled to each other to provide more adhesion. The output from the 4-speed gearbox is coupled to a final drive and reversing gearbox which is provided with a transverse drive shaft and balance weights. This is connected to the driving wheels by connecting rods.

Hydraulic Transmission Hydraulic transmission works on the same principal as the fluid coupling but it allows a wider range of "slip" between the engine and wheels. It is known as a "torque converter". When the train speed has increased sufficiently to match the engine speed, the fluid is drained out of the torque converter so that the engine is virtually coupled directly to the locomotive wheels. It is virtually direct because the coupling is usually a fluid coupling, to give some "slip". Higher speed locomotives use two or three torque converters in a sequence similar to gear changing in a mechanical transmission and some have used a combination of torque converters and gears. Some designs of diesel-hydraulic locomotives had two diesel engines and two transmission systems, one for each bogie. The design was poplar in Germany (the V200 series of locomotives, for example) in the 1950s and was imported into parts of the UK in the 1960s. However, it did not work well in heavy or express locomotive designs and has largely been replaced by diesel-electric transmission.

Governor

Once a diesel engine is running, the engine speed is monitored and controlled through a governor. The governor ensures that the engine speed stays high enough to idle at the right speed and that the engine speed will not rise too high when full power is demanded. The governor is a simple mechanical device which first appeared on steam engines. It operates on a diesel engine as shown in the diagram below. The governor consists of a rotating shaft, which is driven by the diesel engine. A pair of flyweights are linked to the shaft and they rotate as it rotates. The centrifugal force caused by the rotation causes the weights to be thrown outwards as the speed of the shaft rises. If the speed falls the weights move inwards. The flyweights are linked to a collar fitted around the shaft by a pair of arms. As the weights move out, so the collar rises on the shaft. If the weights move inwards, the collar moves down the shaft. The movement of the collar is used to operate the fuel rack lever controlling the amount of fuel supplied to the engine by the injectors.

Fuel Injection Ignition is a diesel engine is achieved by compressing air inside a cylinder until it gets very hot (say 400°C, almost 800°F) and then injecting a fine spray of fuel oil to cause a miniature explosion. The explosion forces down the piston in the cylinder and this turns the crankshaft. To get the fine spray needed for successful ignition the fuel has to be pumped into the cylinder at high pressure. The fuel pump is operated by a cam driven off the engine. The fuel is pumped into an injector, which gives the fine spray of fuel required in the cylinder for combustion.

Fuel Control

In an automobile engine, the power is controlled by the amount of fuel/air mixture applied to the cylinder. The mixture is mixed outside the cylinder and then applied by a throttle valve. In a diesel engine the amount of air applied to the cylinder is constant so power is regulated by varying the fuel input. The fine spray of fuel injected into each cylinder has to be regulated to achieve the amount of power required. Regulation is achieved by varying the fuel sent by the fuel pumps to the injectors. The control arrangement is shown in the diagram left. The amount of fuel being applied to the cylinders is varied by altering the effective delivery rate of the piston in the injector pumps. Each injector has its own pump, operated by an engine-driven cam, and the pumps are aligned in a row so that they can all be adjusted together. The adjustment is done by a toothed rack (called the "fuel rack") acting on a toothed section of the pump mechanism. As the fuel rack moves, so the toothed section of the pump rotates and provides a drive to move the pump piston round inside the pump. Moving the piston round, alters the size of the channel available inside the pump for fuel to pass through to the injector delivery pipe. The fuel rack can be moved either by the driver operating the power controller in the cab or by the governor. If the driver asks for more power, the control rod moves the fuel rack to set the pump pistons to allow more fuel to the injectors. The engine will increase power and the governor will monitor engine speed to ensure it does not go above the predetermined limit. The limits are fixed by springs (not shown) limiting the weight movement.

Starting A diesel engine is started (like an automobile) by turning over the crankshaft until the cylinders "fire" or begin combustion. The starting can be done electrically or pneumatically. Pneumatic starting was used for some engines. Compressed air was pumped into the cylinders of the engine until it gained sufficient speed to allow ignition, then fuel was applied to fire the engine. The compressed air was supplied by a small auxiliary engine or by high pressure air cylinders carried by the locomotive. Electric starting is now standard. It works the same way as for an automobile, with batteries providing the power to turn a starter motor which turns over the main engine. In older locomotives fitted with DC generators instead of AC alternators, the generator was used as a starter motor by applying battery power to it.

To V or not to V Diesel engines can be designed with the cylinders "in-line", "double banked" or in a "V". The double banked engine has two rows of cylinders in line. Most diesel locomotives now have V form engines. This means that the cylinders are split into two sets, with half forming one side of the V. A V8 engine has 4 cylinders set at an angle forming one side of the V with the other set of four forming the other side. The crankshaft, providing the drive, is at the base of the V. The V12 was a popular design used in the UK. In the US, V16 is usual for freight locomotives and there are some designs with V20 engines. Engines used for DMU (diesel multiple unit) trains in the UK are often mounted under the floor of the passenger cars. This restricts the design to in-line engines, which have to be mounted on their side to fit in the restricted space.

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).

One of the earliest pictures of railways in India 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. So in this scheme, a WDM-3A refers to a 3100 hp loco, while a WDM-3F would be a 3600 hp loco. Note: This classification system does not apply to steam locomotives in India as they have become non-functional now. They retained their original class names such as M class or WP class.

The classification syntaxes

Model of a (decommissioned) WP Steam Locomotive (1:3 size) at Guntur Division. The first letter (gauge)    

W-Indian broad gauge (The "W" Stands for Wide Gauge - 5 Feet) Y-metre gauge (The "Y" stands for Yard Gauge - 3 Feet) Z-narrow gauge(2 ft 6 in) N-narrow gauge (2 ft)

The second letter (motive power)     

D-Diesel C-DC electric (can run under DC traction only) A-AC electric (can run under AC traction only) CA-Both DC and AC (can run under both AC and DC tractions), '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-Used for shunting (Also known as switching engines or switchers in United states and some other countries) U-Electric multiple units (used as commuters in city suburbs) R-Railcars

For example, in "WDM 3A":    

"W" means broad gauge "D" means diesel motive power "M" means suitable for mixed(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)

Broad Gauge Diesel Locomotives Note: Class names for mainline diesels are according to the new classification scheme, with references to the class names in the old system for those classes that were renamed, or for older classes that are out of use. See the general loco page for an explanation of the new and old schemes. WDM–1(Class name carried over from old system.) 1957 Alco models ("World Series" DL500 or 'FA' loco), Co-Co 12-cylinder 4-stroke turbo-supercharged engine; 1800/1950 hp. 100 of these were supplied in all. Initially (1957-1958) 20 were supplied and used for ore/coal freight on SER, but later also used for the first dieselized expresses on ER and SER, e.g., the Howrah-Madras Mail (doubleheaded by WDM-1's before WDM-2's and WDM-4's were introduced). Most of the WDM-1 locos had CoCo wheelsets (thus differing from FA units in other countries), although some are thought to have had A1A-A1A bogies. The remaining units of this class arrived in 1959. In the late 1990s, the remaining units were all in SER, based at Bondamunda and perhaps some at Waltair and relegated to shunting or piloting duties as they were withdrawn / condemned. There used to be some at Gonda and Gorakhpur, a few used for carrying sugarcane traffic. Today all have been withdrawn. One loco (not working) is at Gonda shed. The very first WDM-1 (#17000) has been ear-marked for preservation at the National Rail Museum ([2/01] not yet refurbished). Comparative Specifications WDM–2 (Class name unchanged after reclassification.) 2600 hp Alco models (RSD29 / DL560C). Co-Co, 16-cylinder 4-stroke turbo-supercharged engine. Introduced in 1962. The first units were imported fully built from Alco. After DLW was set up, 12 of these were produced from kits imported from Alco (order no. D3389). After 1964, DLW produced this loco in vast numbers in lots of different configurations. This loco model was IR's workhorse for the second half of the 20th century, and perhaps the one loco that has an iconic association with IR for many people. These locos are found all over India hauling goods and passenger trains — the standard workhorse of IR. Many crack trains of IR used to be double-headed by WDM-2 locos; this has decreased now owing to the electrification of most important sections and the use of more powerful locos. A single WDM-2 can generally haul around 9 passenger coaches; twin WDM-2's were therefore used for 18-coach trains. Jumbos – A few locos of the WDM-2 class produced in 1978-79 have a full-width short hood; these are unofficially termed 'Jumbos' by the crew. These range from serial

numbers around 17796 or so to about 17895 or so (17899 and above are known to be 'normal' WDM-2s). These were apparently produced with the idea of improving the visibility for the drivers, but it was learned later that it did not make much of a difference under the typical operating conditions of these locos. Some of these were later modified to have narrower short hoods to look more like the other WDM-2's. Two locos, #17881 and #17882, were trial locos produced by DLW when they were considering shutting down Jumbo production; these look like ordinary WDM-2 locos, even though there are other Jumbos with higher road numbers than them. Some Jumbos have undergone further modifications: Loco #17854 was a Jumbo based at Jhansi in 1981; now [6/04] it has been rebuilt as a WDM-3A locomotive (based at Pune) by DCW, Patiala. The classification WDM-2A is applied to those that were re-fitted with air brakes (most of these therefore have dual braking capability), while WDM-2B is applied to more recent locos built with air brakes as the original equipment (these very rarely have vacuum braking capability in addition, especially if they have been rebuilt by Golden Rock). (However, in the past, before the widespread use of air-brakes, a few modified versions with a low short hood at one end like the WDS-6 were also classified WDM-2A.) A few WDM-2 locos of the Erode shed have been modified and sport a full-forward cab at one end, with the dynamic brake grid, blower, etc. moved between the cab and the traction alternator. The original Alco designs had a 10-day, 3000km maintenance schedule, which was later extended by some modifications to a 14-day schedule. Now [1/02], the schedule is being extended to 30 days by increasing the capacities for various fluids (lubrication oil, etc.), and improving some bearings (mainly, using roller bearings for the suspension). The original WDM-2 bearings were very susceptible to failure. However, given the age of this model, unsurprisingly even locos that have been modified for a 14-day schedule do often require more frequent maintenance or minor repair so they end up being put on a 7-day schedule anyway. WDM-2 locos are excepted from the new mainline diesel classification scheme and will remain classified as WDM-2 and not 'WDM-2F' as they might be in the new scheme based on their horsepower. The first one supplied by Alco was #18040. This one is no longer in use and is now preserved at the National Railway Museum at New Delhi. The second one from Alco, #18041, is currently [7/05] homed at Kalyan shed and is often seen hauling the Diva - Vasai DMU service. The first WDM-2 built by DLW, #18233, is now at Andal shed (not much in use). The last WDM-2's were in the 16000 series. The very last one is #16887. The WDM-2 locos have a max. speed of 120km/h. There are generally speaking no restrictions for running with the long hood leading, although it's been reported that in some cases the practice was to limit it to 100km/h. The gear ratio is 65:18. Some WDM-2 units are being converted [2/02] to have AC-DC transmission (alternator driving DC traction motors) by DCW, Patiala. Golden Rock workshops have also been renovating some WDM-2 locos with new features such as twin-beam headlamps.

Only one WDM-2 loco (#16859, Ernakulam shed) is known to have had cab air-conditioning fitted. This was the first loco to have air-conditioning in India; this was done by the ERS shed in 1997 right after receiving the loco from DLW, but it was disabled later as the auxiliary alternator proved too weak to run the air-conditioner well. A few WDM-2 locos downgraded for shunting duties have been seen marked with a WDM2S class name; e.g., some at Itwari shed [2003] and some at Kurla. A few have also been spotted bearing the class name WDS-2, e.g., those at the Kalyan shed where they are used for shunting. These appear to be quirks of the local shed staff and not officially recognized classifications. DCW Patiala has rebuilt some WDM-2 units to class WDM-3A/WDM-2C specifications. These are a little different from the normal WDM-2C from DLW. They look very similar to WDM-2's, except for a bulge on one of the doors of the hood; this is due to the presence of a centrifugal fuel filter which moved there because the model required larger aftercoolers. There are some other slight differences in appearance. These units have a GE turbocharger and a different expressor with integral air drying facility. They have a Woodwards governor which leads to even running and idling, and (to the great disappintment of Alco smoke fans) reduces the amount of black smoke during intense acceleration. These also have roller bearings for the suspension, improving on the longstanding problem of bearing failures on the regular WDM-2 model. Following the new mainline diesel classification scheme, new WDM-2C's converted or overhauled by DCW, Patiala, are being labelled WDM-3A (new). Brief Notes  

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Builders: Alco, DLW Engine: Alco 251-B, 16 cylinder, 2600hp (2430hp site rating) with Alco 710/720/?? turbocharger. 1000rpm max, 400rpm idle; 228mm x 266mm bore/stroke; compression ratio 12.5:1. Direct fuel injection, centrifugal pump cooling system (2457l/min @ 1000rpm), fan driven by eddy current clutch (86hp @ engine rpm 1000). Governor: GE 17MG8 / Woodwards 8574-650. Transmission: Electric, with BHEL TG 10931 AZ generator (1000rpm, 770V, 4520A). Traction motors: GE752 (original Alco models) (405hp), BHEL 4906 BZ (AZ?) (435hp) and (newer) 4907 AZ (with roller bearings) Axle Load: 18.8 tonnes, total weight 112.8t. Bogies: Alco design asymmetric cast frame trimount (Co-Co) bogies (shared with WDS-6, WDM-7, WAM-4, WCAM-1, WCG-2). Starting TE: 30.4t, at adhesion 27%. Length over buffer beams: 15862mm. Distance between bogies: 10516mm.

Comparative Specifications WDM-2D There are a few WDM-2D units in ER used for push-pull operations (SealdahHasnabad, Ranaghat-Krishnagar, Lalgola-Murshidaba, Bardhaman-Rampurhat). It is not known how they differ from the WDM-2 / WDM-2C classes. WDM–3 (Old class name.) Rarities. Diesel locos with hydraulic transmission -- only 8 were produced, by Henschel (model DHG2500BB). Mercedes Benz MD108DZ20 engines, B-B axles. Built around 1970, IR numbers 18515-18522, works numbers 31300-7. No longer in use, decommissioned at Gooty shed, 1995. The first two had Maybach Mekydro transmissions and the rest had the indigenous Suri transmission. Note:The WDM-3A has nothing to do with the original WDM-3 Henschel locos, and is the new class code for the WDM-2C loco based on the power rating of 3100hp (see below). Comparative Specifications WDM-3A / WDM–2C (Old class name WDM-2C, new class name WDM-3A.) These 3100hp locos are more powerful versions of the WDM-2. The first one was delivered on August 22, 1994. A single WDM-2C could haul a 21-coach passenger train, something that required two of the older WDM-2's. The WDM-2C / WDM-3A also has a rated top speed of 120km/h, and has the same power-pack as the WDG-2 and WDP-2 locos. Early units were air-braked but lately many have been provided dual-braking capability. Dynamic brakes are also provided. The loco has a single cab. Gear ratio 65:18 as with the WDM-2. All recent units have a square profile, but a few early versions have a rounded appearance. Starting in [11/02], even higher powered units (3300hp) have been turned out by DLW, Varanasi, and DCW (DMW), Patiala -- all recent WDM-3A are of 3300hp power rating. DLW has also experimented with improvements to the Alco 251 powerpack to extract 3900hp out of it, and this is being [4/02] tested in a few locomotives.The new class name for these is WDM-3A. WDM-2CA is a variant of the WDM-2C (numbers beyond #14080). Dual brakes? (not confirmed) These units all had right-hand seating for the driver. Later these were all reclassified WDM-3A along with the WDM-2C locos, but a few remain at Erode shed with the old class name on them [7/05]. Brief Notes  

Builders: DLW Engine: Upgraded (by DLW) Alco 251-C (16 cylinder), 3100hp (2900hp site rating) early models, 3300hp from 2003, 1050rpm max / 400rpm idle; direct fuel injection.

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Cooling and fans as with WDM-2. ABB VTC304-15 or Napier NA 295 IR turbocharger. Governor: GE 17MG8 / Woodwards 8574-650. Transmission: Electric with BHEL TA 10102 CW alternator, 1050rpm, 1130V, 4400A. (Earlier used BHEL TG 10931 AZ alternator.) Axle Load: 18.8 tonnes. Wheelset: Co-Co trimount bogie. Starting TE: 30.4t, at adhesion 27%. Length over buffer beams: 15862m Distance between bogies: 10516mm.

Comparative Specifications WDM–3CUpgraded, higher-power versions of the WDM-2C (WDM-3A) loco. These are rated at 3300hp and built by DMW (DCW), Patiala. Since this class appeared only a few have been seen. Two were thought to be undergoing trials [11/03]. The total number is not known. These locos are all thought to be rebuild or upgrade jobs and numbered in the 18xxx range with an R suffix as they are rebuilds (e.g., one probably 18833R at Lucknow [11/03], another 18893R at Gooty [9/04], now [2/05] at Guntakal). It is believed that this class was the trial platform for leading up to the WDM-3D design, and so with the introduction of that class (see below), this line is no longer in production. (Note: Some locos of the WDM-3D class (see below) were initially classified as 'WDM-3C+'.) More recently [7/05] a loco marked WDM-3C, #14147, has been spotted. Its road number puts it in the WDM-3A series, but in its construction it appears to share the body shell, bogies, fuel tank, cowcatcher, and so on with the WDM-3D. It is thought that DLW may be trying out a new variant design as a compromise between the 3100hp WDM-3A which is no longer being produced, and the 3400hp WDM-3D model which has suffered many problems with its electronic systems. For instance, it is possible (this is speculative) that this loco #14147 had a 3300hp powerpack with WDM-3D style (WDG-3A style) high-adhesion bogies, a bigger fuel tank (from the WDG-4) and without the electronic complexity of the WDM-3D. Comparative Specifications WDM–3DA higher-powered version of the basic WDM2C (WDM-3A) class, these locos have a 3300hp powerpack, with available traction power of 2925hp. The engine is an enhanced version of the 16-cylinder Alco 251C model. Max. speed 160km/h. Fabricated (welded) Alco High-Adhesion Co-Co bogies. Starting TE is 36036kgf (353kN). Dual braking systems. Left hand drive, WDG-3A style High Adhesion bogies, air cylinder under footboard, WDP-4 style fuel tanks, engine doors like WDP-4, marker lights outside cabin doors, electronic horn. Improved bogies with stem type vertical and lateral dampers in place of 'eye' type for easier maintenance. High capacity buffers. Components and auxiliaries improved with the aim of making the duty schedule longer between maintenance visits to the shed. Fuel tank capacity 6000l, engine oil sump capacity 1210l.

The WDM-3D is the result of a concerted effort by DLW to incorporate some of the best features of the GM/EMD locomotives (WDP-4/WDG-4) into the proven Alco base technology with which DLW has enormous experience. The WDM-3D uses General Electric's 'Bright Star' microprocessor control system to monitor and control various engine parameters, to detect wheel slip, and to supply power in a phased manner to the traction motors under slipping conditions. (Some later units may have switched to a control unit from Medha.) An oil cooler is provided in this loco, a first for the Alco-based models produced in India. The cab in the first units of this class is a normal metal one, but later units are expected to feature a fibre-glass cab as seen in the WDP-4 (e.g., #20012). (This will result in the dynamic brake resistor grid being moved to behind the cab.) The control desk will also be changed to be similar to that of the WDP-4. [11/08] Only one locomotive (#11121) so far has had cab this modification. Rest of the fleet retain the classic Alco hood design but have had the dynamic brake resistor moved to the roof on the short hood (#11200 onwards?). The first one was built in July, 2003, numbered #11101. Launch livery deep blue with cream stripes, but has possibly been repainted very soon after. Spotted with damaged sandboxes in December 2003 at Bangalore. Maker's plate read 'DM3D-001, July 2003'. The first few units (five, [11/04]) were all homed at Krishnarajapuram but later transferred to Erode. Serial production started in late 2005 with locos being alloted to almost all major BG diesel sheds. Nomenclature: The class name 'WDM-3D' would normally imply 3400hp, however this loco is rated at 3300hp, just like the WDM-3C. Originally when this was developed, it was named WDM-3C+, but apparently IR decided that this was too confusing, and re-classified it as 'WDM-3D' to avoid confusion with the WDM-3C class. In addition, the 3500hp WDM-3E class (see below) is referred to as 'WDM-3D without equalizer' in IR documents, so the class name 'WDM-3D' is somewhat ambiguous as it may refer to either the 3300hp or the 3500hp loco.. Brief Notes              

Builders: DLW Weight: 117t Axle Load: 19.5t Bogies: Alco High-Adhesion Co-Co fabricated bogies. Length: 18626mm Width: 2950mm Height: 4077mm Starting TE: 353kN (36036kgf) Gear ratio: 18:65 Traction Alternator: BHEL TA 10102FV Traction Motor: BHEL 5002AZ CGL 7362A Compressor: 6CD4UC RPM: 390rpm-400rpm idling, 1050rpm at 8th notch Main brake reservoir pressure: 10.4kg/cm2

Comparative Specifications WDM–3E This is a 3500hp loco developed by DLW in 2008, based on the WDM-3D design. (RDSO circulars suggest that some prototypes or early versions may have been rated at 3300hp.) It has a high-adhesion bogie ('HAHS') which has a design modified from similar high-adhesion bogies by the removal of equalizing and compensating mechanisms in order to reduce the unsprung underframe weight of the locomotive (and also to circumvent problems seen with the equalizing and compensating mechanisms in the bogie). It has a permitted speed of 105km/h and a maximum design speed of 120km/h. GM-style dynamic brakes spotted on some. Air-braked. This loco was later redesignated as WDM-3D without equalizer in IR documents, which creates confusion with the 3300hp WDM-3D class noted above. Brief Notes      

Builders: DLW Weight: 118.2t Axle Load: 19.7t Bogies: HAHS bogie without equalizers and compensating mechanisms Starting TE: 373kN (38060kgf) Traction Motor: BHEL 4097

Comparative Specifications WDM–3F This is a 3600hp loco developed by DLW, based on the WDM-3D design (continuing the development that resulted in the WDM-3E loco). It has a high-adhesion bogie without equalizers ('HAHS' bogie) just like the WDM-3E. It has a permitted speed of 105km/h and a maximum design speed of 120km/h. Locos of this class are air-braked. Some of these locos have been spotted with a GM-style short hood and roof-mounted dynamic brake equipment, while others have a rounded, quasi-streamlined hood reminiscent of the WDM-2C units (the ones nicknamed 'baldies' on IRFCA). Brief Notes      

Builders: DLW Weight: 120.0t Axle Load: 20.0t Bogies: HAHS bogie without equalizers and compensating mechanisms Starting TE: ? Traction Motor: GE 752NR

Comparative Specifications WDM–4 (Class name carried over from old system.) There were 72 of these export model SD-24 GM-EMD locos, supplied in 1962. Rated at 2600hp (some earlier units were 2400hp) and 140km/h. Co-Co, 16-cylinder 2-stroke turbosupercharged engines. They were considered a potential alternative to the WDM-2 design from Alco and were superior in many ways, but eventually the Alco loco won as GM did not agree to a technology transfer agreement. They are 2-stroke engines fitted with Woodwards governors. All units of IR were equipped only for vacuum brakes. Top speed generally limited to 120km/h, although they were run at 130km/h regularly for the Howrah Rajdhani, and even run in some speed trials at 145km/h. Haulage capacity 2400t. The Co-Co bogies used for this loco were Flexicoil 'Mark 1' cast steel types. All were eventually based at NR's diesel shed at Mughalsarai. The Doon Exp. was one of the first to get these locos (it was also one of the first major trains to switch from steam). Most prominently, the Howrah Rajdhani was hauled by a WDM-4 at one time, as were many other prestigious trains (AC Exp. (now Poorva), Himgiri, and Kashi-Vishwanath Exps.). Later they used to haul local area passenger trains on the Dehradun - Moradabad - Lucknow - Varanasi Mughalsarai - Buxar - Patna - Howrah sections. The Bareilly-Mughalsarai Passenger was probably the last train to get these locos. These locos could haul around 9 passenger coaches; for the 18-coach Rajdhani and other trains they were invariably used with two locos coupled together. Comparative Specifications WDM–6 (Class name carried over from old system.) Rarities! DLW built just two of these locos, which have a short centre-cab with a long hood and a short hood. Nos. 18901, 18902, assigned to ER, built in July 1981 and in 1982, and currently [4/00] based at Burdwan and handling departmental duties and occasional shunting. Known as 'Maruti' or 'chutka gari' by the staff. They are 1350hp Bo-Bo locos with the same 6-cylinder inline engine (Alco 251D-6 variant) and traction motors (4), and hood superstructure, as the YDM4 locos, with a WDM-2 underframe. The power rating of the YDM-4 powerpack is too low to haul anything more than very small rakes, so it's not clear exactly what IR had in mind when these locos were designed and built. Perhaps they were to take on short-haul commuter and suburban services, a task which the DMUs and MEMUs have proved good at. The Bo-Bo bogies of these locos are of a fabricated design, similar to those seen on the WDP-1, apparently not related to any other diesel loco bogies found on IR although perhaps loosely based on the Flexicoil models.

Comparative Specifications WDM–7 (Class name carried over from old system.) Fifteen of these locos were built from June 1987 through 1989. A few were at Erode earlier but later all were transferred to Ernakulam. More recently [8/02-11/02] several (#11003/06/07/08/09/13) have been seen being used as shunters at Chennai Central or for light passenger haulage. Some are now in Golden Rock livery while others are still in Ernakulam livery. A few may [11/02] still be at Ernakulam, but it appears that all are destined to be moved to Chennai or Golden Rock to work odd jobs. These Co-Co diesel-electrics were designed for branch-line duties (top speed 105km/h). They have bodies with two 3-axle bogies and are similar to the WDM-2 in appearance. The powerpack is a 12-cylinder Alco 251B unit. They are now used mostly for shunting, and occcasional branch-line duties on the Trivandrum - Kottayam, Cochin - Alleppey, and Cochin - Trivandrum sections. The first 10 have generators and a top speed of 105km/h. The last 5 in this series have dynamic brakes, alternators, and a top speed of 100km/h. Both batches have a 94:17 gear ratio. Brief Notes     

Builders: DLW Engine: Alco 251B-12 variant, 2000hp Transmission: Electric, with BHEL TG 10931 AZ generator — DC shunt wound (first 10), or BHEL TA 10105 AZ alternators — 3 phase star (the last 5) Gear ratio: 94:17 Fuel capacity: 5000l

Comparison of air brakes and vacuum brakes Parameter Principle of working

Pressure

Pipe diameter

Air Brakes The compressed air is used for obtaining brake application. The brake pipe and feed pipe run throughout the length of the coach. Brake pipe and feed pipe on consecutive coaches in the train are coupled to one another by means of respective hose couplings to form a continuous air passage from the locomotive to the rear end of the train. The compressed air is supplied to the brake pipe and feed pipe from the locomotive. The magnitude of braking force increases in steps with the corresponding reduction in brake pipe pressure and vice-versa. Effective cylinder pressure = 3.8kg/cm2 Feed pipe - 6kg/cm2 Brake pipe - 5kg/cm2 Feed pipe - & 25 Bore Brake pipe - & 25 Bore

Vacuum Brakes The vacuum brake system derives its brake force from the atmospheric pressure acting on the lower side of the piston in the vacuum brake cylinder while a vacuum is maintained above the piston. The train pipe runs throughout the length of the coach and connected with consecutive coaches by hose coupling. The vacuum is created in the train pipe and the vacuum cylinder by the ejector or exhauster mounted on the locomotive.

Effective pressure on piston 0.kg/cm2 Nominal vacuum on train pipe 510mm. Train pipe - & 50 Bore

Components of air brake and vacuum brake systems Air Brakes Brake pipe and feed pipe (twin pipe system for coaching stock, single pipe system for goods stock). Air brake cylinder - 355mm dia Distributor Valve Passenger Emergency Alarm Signal Device Passenger Emergency Valve Guard's Emergency Valve Slack Adjuster Hose coupling for brake pipe and feed pipe Auxiliary reservoir 100 l capacity Cut off Angle cock Check valve with choke Dirt collector

Vacuum Brakes Train pipe -- single pipe

Vacuum brake cylinder- 24" type 'F' Alarm chain apparatus Clappet Valve Guard's Van Valve Slack Adjuster Direct Admission Valve Hose coupling for train pipe Vacuum reservoir 320 l capacity

Advantages of air brakes over vacuum brakes Parameters Emergency braking distance (4500 t level track, 65 kmph) Brake power fading Weight of equipment per wagon (approx.) Pressure Gradient

Preparation time in departure yards (45 BOX or 58 BOXN) Safety on down gradients Overall reliability

Air Brakes 632m

Vacuum Brakes 1097m

No fading 275kg

At least by 20% 700kg

No appreciable difference in air pressure between locomotive and brake van up to 2000m. Less than 40 minutes.

Steep reduction in vacuum in trains longer than 600m. Up to 4 hours.

Very safe

Needs additional precautions Satisfactory

Very good

Schematic diagrams Single-pipe System

Twin-pipe System

Comparison of conventional and bogie-mounted air brakes Parameters Bogie cylinder mounting location No. of air brake cylinders / coach Size of cylinder Slack adjuster Brake block

Conventional Air Brakes Underframe

Bogie frame

2

4

14" External

8" Integral with the air brake cylinder High friction 'K' type composite block

Conventional

Bogie-mounted Air Brakes

Comparison of single-pipe and twin-pipe systems Parameters Principle of operation

Single Pipe The operation is same as that of the twin pipe system except that the auxiliary reservoir is charged through the D.V. instead of feed pipe, since there is no feed pipe in single pipe system.

Charging auxiliary reservoir B.C. and A.R. pressure equalisation Release of brakes (reduction in brake cylinder pressure) Colour

Discontinued during brake application

Pressure

Brake pipe - 5kg/cm2

Twin Pipe The Brake pipe is charged to 5kg/cm2 by the driver's brake valve. The auxiliary reservoir is charged by the feed pipe at 6kg/cm2 through a check valve and choke. The brake cylinder is connected to the atmosphere through a hole in the D.V. when brakes are under fully released condition. To apply brakes, the driver moves automatic brake valve handle either in steps for a graduated application or in one stroke to the extreme position for emergency application. By this movement the brake pipe pressure is reduced and the pressure differenced is sensed by the D.V. against the reference pressure locked in the control reservoir. Air from the auxiliary reservoir enter the brake cylinder and the brakes are applied.At the time of release the air in the brake cylinder is vented progressively depending upon the increase in the brake pipe pressure. When the brake pipe pressure reaches 4.8kg/cm2 the brake cylinder is completely exhausted and brakes are fully released. Uninterrupted

Occurs during prolonged brake application

Does not occur

Proportionate to build up of A.R pressure

Auxiliary reservoir is continuously charged through feed pipe

Brake pipe – Green Feed pipe - White Brake pipe - 5kg/cm2 Feed pipe- 6kg/cm2

Maintenance of broad gauge class diesel locomotive 1. Preventive maintenance : The care and servicing by personnel for the purpose of maintaining equipment and facilities in satisfactory operating condition by providing for systematic inspection, detection, and correction of incipient failures either before they occur or before they develop into major defects. 2. Maintenance, including tests, measurements, adjustments, and parts replacement, performed specifically to prevent faults from occurring. Preventive maintenance can be described as maintenance of equipment or systems before fault occurs. It can be divided into two subgroups: 1.Planned maintenance 2.condition-based maintenance. The main difference of subgroups is determination of maintenance time, or determination of moment when maintenance should be performed. While preventive maintenance is generally considered to be worthwhile, there are risks such as equipment failure or human error involved when performing preventive maintenance, just as in any maintenance operation. Preventive maintenance as scheduled overhaul or scheduled replacement provides two of the three proactive failure management policies available to the maintenance engineer. Common methods of determining what Preventive (or other) failure management policies should be applied are; OEM recommendations, requirements of codes and legislation within a jurisdiction, what an "expert" thinks ought to be done, or the maintenance that's already done to similar equipment, and most important measured values and performance indications. To make it simple:  

Preventive maintenance is conducted to keep equipment working and/or extend the life of the equipment. Corrective maintenance, sometimes called "repair," is conducted to get equipment working again.

The primary goal of maintenance is to avoid or mitigate the consequences of failure of equipment. This may be by preventing the failure before it actually occurs which Planned Maintenance and Condition Based Maintenance help to achieve. It is designed to preserve and restore equipment reliability by replacing worn components before they actually fail. Preventive maintenance activities include partial or complete overhauls at specified periods, oil changes, lubrication and so on. In addition, workers can record equipment deterioration so they know to replace or repair worn parts before they cause system failure

Cooling Like an automobile engine, the diesel engine needs to work at an optimum temperature for best efficiency. When it starts, it is too cold and, when working, it must not be allowed to get too hot. To keep the temperature stable, a cooling system is provided. This consists of a

water-based coolant circulating around the engine block, the coolant being kept cool by passing it through a radiator. The coolant is pumped round the cylinder block and the radiator by an electrically or belt driven pump. The temperature is monitored by a thermostat and this regulates the speed of the (electric or hydraulic) radiator fan motor to adjust the cooling rate. When starting the coolant isn't circulated at all. After all, you want the temperature to rise as fast as possible when starting on a cold morning and this will not happen if you a blowing cold air into your radiator. Some radiators are provided with shutters to help regulate the temperature in cold conditions. If the fan is driven by a belt or mechanical link, it is driven through a fluid coupling to ensure that no damage is caused by sudden changes in engine speed. The fan works the same way as in an automobile, the air blown by the fan being used to cool the water in the radiator. Some engines have fans with an electrically or hydrostatically driven motor. An hydraulic motor uses oil under pressure which has to be contained in a special reservoir and pumped to the motor. It has the advantage of providing an in-built fluid coupling. A problem with engine cooling is cold weather. Water freezes at 0°C or 32°F and frozen cooling water will quickly split a pipe or engine block due to the expansion of the water as it freezes. Some systems are "self draining" when the engine is stopped and most in Europe are designed to use a mixture of anti-freeze, with Gycol and some form of rust inhibitor. In the US, engines do not normally contain anti-freeze, although the new GM EMD "H" engines are designed to use it. Problems with leaks and seals and the expense of putting a 100 gallons (378.5 litres) of coolant into a 3,000 hp engine, means that engines in the US have traditionally operated without it. In cold weather, the engine is left running or the locomotive is kept warm by putting it into a heated building or by plugging in a shore supply. Another reason for keeping diesel engines running is that the constant heating and cooling caused by shutdowns and restarts, causes stresses in the block and pipes and tends to produce leaks.

Lubrication Like an automobile engine, a diesel engine needs lubrication. In an arrangement similar to the engine cooling system, lubricating oil is distributed around the engine to the cylinders, crankshaft and other moving parts. There is a reservoir of oil, usually carried in the sump, which has to be kept topped up, and a pump to keep the oil circulating evenly around the engine. The oil gets heated by its passage around the engine and has to be kept cool, so it is passed through a radiator during its journey. The radiator is sometimes designed as a heat exchanger, where the oil passes through pipes encased in a water tank which is connected to the engine cooling system. The oil has to be filtered to remove impurities and it has to be monitored for low pressure. If oil pressure falls to a level which could cause the engine to seize up, a "low oil pressure switch" will shut down the engine. There is also a high pressure relief valve, to drain off excess oil back to the sump.