Locomotives — General Information – II


Q. What's the ‘tractive effort’ of a locomotive?

The ‘tractive effort’ is a measure of how large a load the loco can pull and set in motion from a standstill — the maximum force it can exert at the drawbar or coupling. While the raw horsepower rating of the loco is important, it is not the whole story. The loco's weight also comes into play, as a heavier loco can pull a larger load without its wheels slipping. Once the wheels begin slipping, the force that can be exerted by the loco drops dramatically. (Slipping occurs more with the front wheels because the front of the loco tends to lift slightly due to the reaction torque exerted by the rails on the loco.) Modern locos tend to have electronic slip control to control the power applied to each axle separately to minimize slip and maximize the tractive effort under different conditions.

Q. What's the method that IR uses to couple together multiple locos? or, What's ‘Locotrol’?

Two to four or so locos can usually be coupled together to operate automatically, without any special provisions, with the crew manning only one of them. (This mode of operation is known as ‘Multiple Unit’ operation, or ‘MU’.)

Using more than about 4 or 5 locos together without some form of automatic control for them is problematic because couplings come under excessive strain and break. A system known as ‘Locotrol’ is used on IR, which couples 3 to 5 locos at the head of a train, and one or two somewhere in the middle of the train, and possibly another two or three at the rear. The locos at the middle and rear of the train are radio-controlled by the crew at the head of the train. This system is used in some places for heavy freight sections. It was introduced with WDM-2's on the Kirandul-Kottavalasa line (near Vishakapatnam) in 1988 by SER. That line is now electrified and multiple WAM or WAG formations are used instead. Locotrol is (or was) also used on the Kulem-Londa section.

With multiple locos lashed up for MU operation, there are MU cables that pass between successive locos, which carry the control signals between the manned loco and the others. WDM-2 locos have a single MU cable, whereas the older WAG and WAM series use three MU cables, which also carry two connections for the tap-changers in the locos. The newer WAP-5 and WAG-9 locos use a single MU cable. The absence of this MU cable indicates manual coupling of locos -- in this case, each loco is manned by crew, and they use horn or hand signals to communicate across the locos. Such non-automatic coupling can also be used for incompatible classes of locos, e.g. to couple a WDM-2 with a WAG loco in rare instances where the required electric loco wasn't available. Even with some of the newer locos, coupling may not be possible for different classes of locos: e.g., a WAG-5 and a WAG-7 cannot be MU'd together and require separate crews for operation.

In some cases the local loco sheds or workshops have carried out experimental modifications to locos to allow multiple unit operation even in cases where the locos were not designed for MU'ing originally. The Moula Ali shed of SCR, for instance, carried out an experiment in the 1990s to MU WDS-4 shunters to allow MU'd pairs of these to shunt long (24-coach) passenger rakes (SCR had an especially high number of 24-coach train services and not enough shunting power to match). Normally a single WDS-4 can only shunt up to about an 18-coach passenger rake. The experiment with MU'd WDS-4 did not work despite a lot of improvization and experimentation by Moula Ali and eventually this was dropped, as old WDM-2's, and even WAM-4 or WAG-5 locos started being retired from mainline operations and becoming available for tasks like shunting.

IR never adopted the practice of designating locos as ‘A’ or ‘B’ units for coupling. All locos could be used as either a master or slave loco in coupled configurations. A few pairs of locos were sometimes kept in fixed-formation (mostly WDM-2 pairs); in such cases, both locos in the pair are usually oriented with their short hoods facing outwards (i.e., so that the short hood leads no matter which direction the locos travel in). (This is not universal practice, however, as lash-ups the other way around have been seen.)

Often, different locos may be seen coupled together, such as a WDG-2 with a WDM-2A.

Q. What's the cause of the characteristic jerk or momentary loss of power felt when a WDM–2 accelerates?

The WDM-2 loco, like most diesel-electric locos, has several configurations of its traction motors that are used as the loco accelerates from rest (Series Parallel - Series Parallel Shunt - Parallel - Parallel Shunt, and weak field configurations). There are three important transitions: At 30.8-39km/h 2S-3P Full Field to 2S-3P Weak Field, at 48-55km/h 2S-3P Weak Field to 6P Full Field, and at 88-90km/h 6P Full Field to Weak Field. For the transition at 39km/h (it can actually happen anywhere between 30km/h and 45km/h), the generator's fuel supply is cut and it is momentarily switched off to avoid sparking and strain on the switchgear. This momentary loss of power can usually be felt throughout the entire train, and is very characteristic of this loco. It is much stronger than the jerks or blips in the acceleration felt at the other transitions of the motors. (This is also seen in other similar Alco models; railfans have reported the same distinct jerk in Alco diesels used in Greece, for instance.) The WDP-2 loco has one transition at 55-62km/h although it is not quite as pronounced.

Q. Why do trains sometimes feel like they are momentarily rolling backwards (or forwards) just after coming to a halt?

Today, almost all braking of trains moving at speed is done using the train brake system which activates (air) brakes along the length of the entire rake. The loco brake system is not used for bringing the train to a halt. However, as soon as the train comes to a halt, most drivers switch immediately to the loco brake system to hold the train at a standstill, and release the train brakes so as to give the system the maximum time to recharge. In the instants between releasing the train brakes and applying the loco brakes after the train has been brought to a standstill, the train may sometimes move a small amount if the place where it has been stopped is on a gradient.

Q. I've heard that some locos have 'cruise control'. What does this mean?

Some locomotive classes such as the WAP-5 and WAP-7, as well as the WAG-9, have controls in the cab that can 'lock' the train to travel at a certain speed (the speed at the time the control or button is set). The button is known as the 'BPCS' button. The computerized loco controls then manage the tractive effort and braking effort and attempt to keep the speed to within +/- 2km/h of the desired speed. In this mode, the driver does not have to do anything further except to respond to the alerter system (see below) within the stipulated intervals, and to use the horn as appropriate. Older locomotives without computerized controls do not have any such provision for 'cruise control'.

Q. What driver vigilance or driver alertness systems are used by IR in its locomotives?

Several loco classes have speed limiters with buzzers that go off when the prescribed speed is exceeded. In some cases these may also result in the application of brakes. Some WAP-4 locos have the buzzer system and it is set for a speed of 130km/h although they are capable of going faster, while a few WAM-4 locos have it at 110km/h (although not all WAM-4 locos have the buzzer system as it requires a relatively more recent speedometer assembly to be retrofitted in them). Some WAG-5 locos and others also have such warning systems. The WCAM-3 loco, limited to 105km/h by its bogies, has the buzzer set to its top speed.

The newer loco classes (WAP-5, WAP-7, WAG-9) have provisions in their original designs for setting a speed limit, which, if exceed results not only in the warning buzzer/light going off but also apply the emergency brakes to slow down to below the prescribed speed. This system, however, is not thought to be actually deployed in any of the locos currently in use. The top speed limit can be set in software (160km/h for WAP-5, 140km/h for WAP-7, 100km/h for WAG-9). In the WAP-5, WAP-7, and the WAG-9, the driver's job is easier in terms of not having to worry about exceeding the speed limit because these locos have provision for cruise control (constant speed settings) -- see above. However, the driver does have to activate the vigilance system periodically, as explained below, even when the cruise control is on.

Vigilance systems in the form of 'dead-man pedals' are provided in some locos, such as the WAP-7. In the WAP-7 system, the vigilance pedal (PVEF) has to be depressed periodically; alternatively a button on a panel can also be depressed. If this is not done, and if the master controller is not being used for braking or acceleration, and if the A9 or SA9 (train / loco brakes) are not being used (any of which temporarily override the vigilance system), an alarm is sounded. This must be acknowledged by the pedal or switch; if acknowledgement is not provided with 60 seconds, power to the traction motors is cut. If there is no acknowledgement within 10 seconds after this, the main circuit breaker (DJ) is opened and the brakes are applied bringing the loco to a halt. Resetting this afterwards involves a number of manual steps at the main computer unit ('HBB') and re-building brake pressure. A similar system is provided in the WDP-4 and WDG-4, as well as in the WAP-5 and WAG-9.

Q. How are locomotives 'run in' to prepare them for service?

New locomotives are run in for a period of time after being commissioned from the factory in order to shake out any possible initial manufacturing defects and for all the components to settle into normal wear and usage patterns. In order to give the loco a reasonable load and much starting and stopping opportunities, usually the new loco is run in by hauling a passenger train rather than running it by itself (which also avoids the need to free up block sections for the light loco).

Normally an ordinary stopping passenger is used and not a mail or express train since the latter are less 'tolerant' of delays and breakdowns if any, and also since the running speeds on them tend to be higher. The normal loco for the passenger train is usually coupled in with the train too, but left unpowered, to allow it to take over in case the new loco develops a fault. Sometimes some passenger trains are specially designated for the running in of new locos (e.g., the Tata Passenger which often carries new locos from CLW towards Lallaguda, Erode, Bhusawal, Ajni, etc. The Kazipet Passenger is used for taking locos from Nagpur to Kazipet). These trains are often also the ones that are usually used for coupling dead locos for transport back to sheds.

Freight trains are usually not used for such movement of new or dead locos since they tend to run without stops for long periods, and also because delays due to coupling or uncoupling the additional loco(s) would in some cases be excessive.

Q. What does 'microprocessor control' for a locomotive mean?

'Microprocessor control' can mean a few different things. A few of the newer electric locomotive models such as the WAP-5 or WAG-9 with complex 3-phase AC drives have circuitry and equipment controlled by microprocessors. In these, the microprocessor or computerized control is an integral part of the locomotives' design. Some of the newer diesel locos such as the WDG-4, WDP-4, WDM-3D, etc., also use a fair bit of microprocessor control for their onboard systems. These advanced locomotives can be truly described as being computer-controlled or microprocessor-controlled.

However, the term 'microprocessor control' is also widely applied to certain models of WAP-4 and other locos that have been retrofitted with a monitoring system that uses computerized circuitry to replace some of the electromechanical relays and switches that were part of the original design of these locos. Systems monitored by the microprocessor circuits include the DJ, silicon rectifier, battery chargers, etc. The advantage of this is that the status of the monitored equipment is displayed on an LCD panel in front of the driver and he does not have to look around and inspect the state of each relay or switch behind him manually. In such cases the microprocessor does not actually control anything.

Typical relays replaced by the monitoring circuits are QV60, QV61, QV61, QV63, QV64, QV65, QVLSOL, etc. Among the WAP-4 locos, 'Yugantar', #22591, was the first one to get such a microprocessor-based monitoring system (all later locomotives in the series seem to have been produced or retrofitted with this). Many sheds (Kanpur, Vadodara, etc.) display the annotation 'microprocessor controlled' very prominently on the loco itself. A few older locos (e.g., #22547) have also been retrofitted with the microprocessor monitoring. Apart from WAP-4 locos, some WAG-7 locos (Jhansi, Kanpur) have also been retrofitted with such systems.

Q. What does 'Static Converter Fitted' or similar annotation mean on a locomotive?

Locos traditionally had a rotary converter (of Arno make) to generate 3-phase AC on board to power auxiliary equipment such as traction motor blowers, compressors, exhausters, etc. Starting in the 1980s static converters using solid-state circuitry to generate 3-phase AC on board have been used instead of the Arno converter, driving up efficiency and reliability by eliminating the moving parts that the Arno contained.

Static convertors and microprocessor control have now become standard kit for all new production WAP-4s beginning from the 22640 series. Static convertors have become standard for all new WAG-7's too. This has also meant that the new locos may not carry the 'Static Convertor' or 'Microprocessor Fitted' markings despite being equipped with these systems. These locos are now being distributed to all sheds.

Q. What kinds of bogies (trucks) are used by IR's locomotives?

For mainline BG locomotives, there were, until the 1980s, two main alternatives. The venerable WDM-2 which existed (exists) in vast numbers, along with the WDS-6, WAM-4, WAG-5, and some of the WCAM-1/2 locos used an Alco design asymmetric trimount (Co-Co) cast bogie design. Most other mainline BG locos used some variant of the GM-EMD 'Flexicoil' design, starting with the 'Mark 1' version for the WAP-1 and WAP-4 locos as well as the EMD-designed WDM-4 locos (export model SD-24), and variants known as 'Mark 2' or 'Mark II', 'Mark 3', etc., for other electrics such as the WAP-3. These were all cast bogies. RDSO experimented a lot with the designs of these bogies, to improve top speed, ride characteristics, etc., so that many variations can be found. The Flexicoil model was originally designed by GM-EMD and used in the American SD-7 locomotive of the 1950s. The innovation of the Flexicoil design at the time it was introduced was the isolation of lateral vibration by a swing hanger.

A newer generation of the Flexicoil design was introduced later in the form of the 'Mark 4' ('Mark IV') model which had a fabricated bogie frame assembly. This was used for the WAP-6, WDP-3A, and some other classes. These bogies were supposed to work up to 160km/h but turned out to be unsuitable for Indian track conditions at such high speeds and were restricted to 105km/h or so after initial oscillation trials. WDP-3A locos are now allowed to run at 120km/h on select sections such as the Konkan Railway stretch and the WR trunk route. The Mark IV Flexicoil bogies have some adhesion-increasing characteristics and have a rated top speed of 140km/h. The WAP-7 and WAG-9 locos use an ABB freight bogie design and have been tested and approved for speeds up to 140km/h.

Alco High-Adhesion bogies (which have a fabricated bogie assembly) were also introduced in the 1980s, and are used for the WDG-3A, WAG-7, WCAM-3, WDM-3D, WCAG-1, WCM-6, and other locos such as the Sri Lankan export model of the WDM-2. They are said to have several enhanced characteristics for providing high adhesion and good damping of vertical and lateral oscillations.

In addition there are some odd home-grown models of bogies such as the fabricated Bo-Bo bogies seen on the WDP-1 (based on a variant of the Flexicoil design) and WDM-6 locos. MG and NG locos have their own bogie designs, in most cases carried forward and adapted from the original imported loco models -- there has not been a lot of active work at RDSO on developing new bogie designs for these narrower gauges.

Q. Were/are battery-powered electric locos used in India?

Yes. Western Railway inherited from the BB&CI Railway two broad-gauge battery-powered shunters that were used in a yard that was not electrified (and where the use of steam or diesel locos was thought to be too noisy). There is a picture of one of these in Jal Daboo's book. These were locomotives built in England in 1927, and for their time were among the most powerful battery-electrics.

The NBM-1 class of 2' gauge locos are battery-driven, in use by CR on the NG network around Gwalior. They were manufactured by BHEL in 1987, and have a fairly modern thyristor-based AC motor drive. There were only 3 of them in use. (Are these still being used?)

Battery locomotives have also been used by some industrial concerns and mines or collieries. English Electric supplied two dual overhead/battery electric locomotives to a colliery in Ballarpur in the early 1930's. Several battery locomotives have also been supplied by Indian manufacturers.

Q. Serial numbers: How are/were locomotives numbered in India?

Prior to 1940 or so, each railway company had its own system of numbering different classes of locomotives. Beginning in the early 1940s, the state began taking over several of the railway companies, and newer locomotives acquired thereafter were allotted numbers based on the ‘IRS’ (and later ‘IGR’) classes; but numbers were duplicated across the different railways well into the 1950s. Some effort was made (especially by NR and WR) after 1952, when the zonal railways were set up, to avoid duplication of locomotive numbers across the zonal railways.

In 1957, new ‘all-India’ numbers were issued for most working locomotives in all the zonal railways to establish unique numbers throughout the country. The all-Indian numbers had blocks for each class of locomotive: e.g., numbers 22301 - 22500 were reserved for the BG XD class locos, and numbers 1000-1500 were reserved for MG diesel shunters. Some locos, such as the WCG-1 shunters, continued to be numbered with their old numbers together with the all-India numbers (e.g., 20038 (4513) where the number in parentheses might be, for instance, the old GIPR loco number). Over the years, the decline of steam and the growth in diesel and electric motive power has led to the reuse of numbers from blocks originally meant for steam locomotives for various diesel or electric locos.

A locomotive which has undergone extensive repair work (perhaps following a collision) usually has an ‘R’ suffixed to the serial number. The ‘R’ suffix is also used for mid-life reconditioning overhauls such as those performed by DCW, Patiala or Golden Rock workshops. DCW, Patiala always used the 'R' suffix for overhauled WDM-2 locos (not upgraded to WDM-2C) before March 2000. Later, they used to renumber locos with the 'R' suffix even when they carried out the class upgrades to WDM-2C / WDM-3A (starting with 18690R). However, in recent years it's been seen that as these upgraded locos are repainted by the various loco sheds where they are homed, sometimes the 'R' is omitted. E.g., Lucknow shed's WDM-3A #18476, the oldest (1968) loco converted to a WDM-3A, no longer [2004] sports the 'R' suffix. Such locos (which had the 'R' in the serial number but later lost it) will always be in the shed-specific livery and not in the standard DCW livery.

If a loco, coach, or wagon is condemned (perhaps following severe damage in an accident), or not working well enough so that it is notionally written off, it may nevertheless be used after repairs in some limited circumstances; for example, condemned locos have been put to good use as shunting engines in yards. In such cases, a ‘0’ is prefixed to the serial number.

From about 1999, some sheds of IR (perhaps only on SR?) have begun the practice of adding a 2-digit year of manufacture in large stencilled numerals next to the road number for some electric locos, such as WAP-4's or WAM-4's. E.g., some SR WAP-4's sport road numbers like 22219/97, 22536/02, 22626/05, etc. (the first two from Erode, the last from Arakkonam [7/06]).

Serial numbers were earlier painted or stencilled on in small numerals on the side of the loco cab; for locos up until the 1950s, usually the initials of the old railway company were painted on much larger. Since the late 1970s or early 1980s IR has been painting the serial numbers in large numerals on the sides of the loco bodies. Often the numerals are enclosed in a stylized oval or hexagonal frame that connects up to a stripe or stripes running along the length of the body.

This no longer applies to newly produced locomotives. New diesels do not have numbers painted on the long hoods. WAP-5s and WAP-7s do not have numbers painted on the sides. WAG-9s starting from the 3106x series again have standard sized numbers painted on the sides. Earlier WAG-9s had road numbers painted near cab doors under the yellow band in half the standard size. This was done away with for a few units starting 3104x and 3105x.

Serial number ranges for diesel and electric classes are in the loco specifications section.

Serial numbers are not always serial! Sometimes locos in the same class are assigned numbers out of sequence. The most recent example is that of the indigenous WAP-5 locos from CLW; the first was 30011, the second was 30013, and the third was 30012.

Hugh Hughes' books are probably the best source of detailed numbering information for locomotives in India up till 1990.

Special-purpose units have various numbering schemes. E.g., EMU and DMU units sometimes have numbers such as ‘MC 0004’ where the MC stands ‘motor coach’. Accident relief vans are numbered, e.g., as ‘ARMV 5101’ etc. (ARMV = Accident Relief Medical Van). Cranes, diesel-electric tower cars for maintaining the OHE, and other such vehicles are numbered separately. DMUs of various kinds have their own numbering system which resembles the road numbers of locomotives in consisting just of digits without any alphabetic prefixes or suffixes. The 1400hp HPDMUs have been seen numbered in the 14xxx and 15xxx range.

Locomotive Plate Numbers Almost every IR locomotive has a manufacturer's plate with information such as the date of manufacture on it, along with a number (also known as a works number), although the works number is often missing for electric locos. The plates are usually located on the side of the loco, either on the main body or on the cab. On several of the early imported locomotives, the original plates have been removed or lost over time, or painted over so that they are now unreadable. Different manufacturers use different conventions for plates. The convention for Alco / DLW plate numbers is explained below. WCM-1 and WCM-2 DC electrics have / had plates with their dates of manufacture along with the English Electric / Vulcan Foundry works numbers. CLW and BHEL loco plates only show the maker's name, without any works number or other similar information. New plates are sometimes attached to a loco when it undergoes serious overhauling. The information on these new plates may then just show the date of the overhaul, and may even show the new class code for the loco if the classification has changed since the loco was originally built (e.g., WDG-2 being re-classified as WDG-3A). This can create some confusion (for railfans!) in assessing the chronology of different locos.

Alco/DLW (WDM-2) plate numbers (Explanation from Sheldon Perry, adapted.) A typical plate number for a WDM-2 locomotive may be I-3389-03-0292. The "I" stands for India. The "3389" is a portion of a larger Alco order numbering system. (The DLW order is also referred to as D3389.) For example, (G)3388 was a Goodwin order for DL500's. (M)3390 was a cancelled MLW order for RS-18/DL718's, and so on. (DLW also has/had another order number, I-6026. This was applied to DL535's (YDM-4's). You probably won't find this number on any of the plates though.) The "03" is believed to be some kind of phase in the WDM-2 production series. There are also plates that read I-3389-01-xxxx (the very first WDM-2 locos started with I-3389-01-001) and I-3389-02-xxxx. It is not generally known where these different phases or series have their transitions. The last four digits ("0892") represent the on-going numerical sequence of works numbers. Again, it is worth emphasizing that the works number analysis here applies only to particular Alco/DLW locos (WDM-2 class). Other loco classes have different schemes for their works numbers.


Public-sector locomotives

There are numerous locomotives (WDM-2, WDS-6, and other models) that are used by various public-sector units — power plants, steel or cement plants, collieries, mines, etc. for their internal freight-hauling and marshalling operations. These may have various additional markings or serial numbers, e.g. "BSP" followed by a number indicates a loco of the Bhilai Steel Plant; "NTPC" followed by numbers indicates a loco of the National Thermal Power Corporation. A loco belonging to the Rihand thermal power plant has been seen with the number 'RhSTPP-II No. 04'. There is a rich variety here, which is unfortunately not very well documented anywhere, and is not treated by any of the more detailed works on Indian locomotives such as the books by Hughes, or Simon Darvill's Indusrial Locomotive List. These industrial locomotives can often be seen on IR mainline routes as they travel to and from their maintenance and overhauling facilities which are usually at the bigger regional IR sheds.

Industrial locomotives

Please consult reference works such as Hughes' books for detailed information on the numbering of locomotives used by private industry and public-sector industrial concerns. Hughes' books have a lists of many locomotives sent to the public sector concerns and approximate serial number ranges or years of manufacturers for those manufactured by DLW or CLW. Also see Simon Darvill's Indusrial Locomotive List.

Q. How many locomotives does IR have in its fleet?

As of 1998, IR operated a fleet of about 4,400 diesel locos, and about 2,550 electric locos. In mid-1997, it still counted 85 steam locos in its fleet, although most of those are not in service any more (see the section on the last of steam. In 2005, IR had about 4,800 diesels, 3,065 electrics, and 44 steam locos.

Q. Does IR have push-pull operations?

Push-pull operations are seen in a few places. The Bangalore-Mysore Passenger has a loco at one end and driving trailer cab at the other end for true push-pull operation. The trailer cab is sometimes seen in the middle of a rake instead of the very end (Bangalore-Arsikere-Nanjangud Passenger)

[7/02] The 6057/6058 Sapthagiri Express between Chennai Central and Tirupati (via Renigunta) has a WAM-4 permanently coupled to the rake at one end, with a cabin in the last coach at the other end which has all the controls of the WAM-4 replicated.

Though not strictly push-pull, some suburban or short passenger services are operated with a loco in the middle of a rake instead of at the end (e.g. Diva-Vasai, Solapur-Bijapur). The Diva-Vasai Passenger has 4 coaches on either side of the locomotive; the end coaches are special-purpose modified units and have a driver's cabin, a ladies' compartment, and a luggage compartment. A few trains have a loco at one end and a DMU at the other end, e.g., Diva-Roha.

Q. Where can I find pictures of various kinds of locomotives?

Try the IRFCA Picture Gallery, especially the albums on steam, diesel, and electric locomotives.

Two other good places to start are the loco picture pages at the Indian Train Gallery and RailInIndia. See S Shankar's IR pages for dozens of links and pages on different kinds of locomotives with pictures.

Q. Which locos are the rarest ones on IR?

The situation is changing all the time with many old locos reaching the end of their useful lives. The list below shows the loco classes that can be considered as being really rare on the IR network [1/05].

  • YAM-1 : Only at Tambaram (SR), decommissioned and probably scrapped by now [2006] but were occasionally used for departmental duties as late as 2005.
  • YDM-2 : Only at Golden Rock (SR) and Gandhidham (WR).
  • WCAM-1 : Only at Valsad (WR).
  • WCAM-2, WCAM-2P : Only at Valsad (WR).
  • WCAM-3 : Only at Kalyan (CR).
  • WCM-6 : Only one left.
  • WCG-2 : Only at Kalyan (CR).
  • WCAG-1 : Only at Kalyan (CR).
  • WDP-1 : Only at Tughlakabad (WCR) and Vijayawada (SCR).
  • WDP-2 : Only at Tughlakabad (WCR) and Golden Rock (SR).
  • WDM-3D : Only at Krishnarajapuram (SWR) and Erode (SR).
  • WDM-6 : Only two were built, #18901, #18902; both at Bardhhaman (ER).
  • WDM-7 : Only at Tondiarpet and Ernakulam (both SR).
  • WDS-5 : Only at Mughalsarai (ECR) and Bondamunda (SER).
  • WAG-6A, WAG-6B, WAG-6C : Only at Vishakhapatnam (ECoR).
  • WAP-6 : Only at Asansol (ER).
  • WDG-4 : Only at Hubli (SWR) -- more are expected to be built.
  • WDP-4 : Only at Hubli (SWR) -- more are expected to be built.
  • WAP-5 : Only at Ghaziabad (NR) -- more are expected to be built.
  • WAP-7 : Only at Gomoh (ECR) and Ghaziabad (NR) -- more are expected to be built.
  • WAG-9 : Only at Gomoh (ECR) and Ajni (CR) -- more are expected to be built.
  • WP : The premier passenger locomotive in steam days is now found only at the Rewari steam shed
  • WL : This steam loco is now found only at the Rewari steam shed.
  • Other steam : Steam as a whole rates as being very rare on IR's network today. The 'X' class locos are found only on the Nilgiri Mountain Railway line (Cooonoor shed), and the DHR 'B' class locos are found only on the Darjeeling Himalayan Railway (Tindharia shed). The Rewari shed has some other steam locos, including some MG steam, YG, AWD, etc. A few other steam locos (WP's, WG's, etc.) are found in other zonal railways and used for special excursions. See the section on steam.

Q. Were Garratts used in India?

Yes. Bengal Assam Railway had 2-6-2+2-6-2 Meter Gauge Garrats made by Beyer Peacock & Co. Manchester, the same maker of the earlier Garrats in Burma. A B/W picture of Garrats from Bengal Assam Railway appears on page 19 of Indian Locomotives, Part 2 (Meter Gauge) by Hugh Hughes. There were also a few 4-8-2+2-8-4 MG Garratts in use. One is plinthed at the Guwahati steam shed.

The Bengal Nagpur Railway had several BG Garratts, of classes P (4-8-2+2-8-4), N (4-8-0+0-8-4), NM (??), etc. These were quite powerful, and could haul 2400-ton loads on 1:100 gradients without any problem.

The DHR had a 0-4-0+0-4-0 Garratt (‘class D’, essentially two class B locos put together) built by Beyer Peacock in 1910, on its 2' NG line until 1948. (? Some reports suggest it was working into the mid-1950's.)

Consult Hughes' books for more details of Garratts used in India.

And elsewhere in or around the subcontinent:


Of the total 12 pre-war Garrats in Burma, only 10 were active in 1947. Twelve 2-8-2+2-8-2 were added in 1943 and nine 4-8-2+2-8-4 were added in 1945, all made by Beyer & Peacock. Post war Garrats in Burma were of two types. 12 locos were 2-8-2+2-8-2 and 9 locos were 4-8-2+2-8-4. Four 4-8-2+2-8-4 were transferred to Tanganyika (Tanzania) in 1948 and five 4-8-2+2-8-4 were transferred to East African Railways (Kenya) in 1952, according to Hughes, Indian Locomotives Part 4 page 85.


Garratts were in operation on the Janakpurdham-Jaynagar line until fairly recently.

Sri Lanka

Sri Lanka had BG & NG Garratts. One BG Garratt is now at the Ratmalana Works, Colombo, and another at the Dematagoda Running Shed, Colombo; neither is operational.

Q. What about other articulated locomotives?

Other than the Garratts mentioned above a few articulated locos were used in India. Perhaps the best known are the WCG-1 (EF/1) 1.5kV DC locos ('Crocodile') and the NDM-1 dual-engined diesel loco for the Neral-Matheran hill run. The bonnets of both these types of locos were able to swivel around.

Other articulated locomotives used in the past:

  • NWR's MAS class #460 Mallet (broad gauge)
  • WIPR's IM class Mallets (meter gauge)
  • ISR's double Fairlies, 4 of which went to the Nilgiri under the NMR (meter gauge) (Hughes, part 2, p.70)
  • NWR's KST TS class #180, #181, Kitson-Myers

Q. What is bio-diesel? What are bio-diesel locomotives?

Biodiesel is the name given to various fuels or diesel fuel mixtures that incorporate varying amounts of oils derived from plants. While in western countries interest has centred on soybean oil and other crops' oils for use in diesel engines, in India, local plants such as 'Ratanjyothi' (Jatropha curcas), 'Karanjia' (Pongammia pinnata), and 'Neem' trees have proven useful as sources of oil suitable for use in diesel fuel. The benefits of such fuel mixtures are lower levels of polluting emissions, and lower fuel costs with large-scale cultivation of the plants. Byproducts include oilcake and glycerine. The characteristics of the diesel fuel have to be carefully balanced when these bio-diesel additives are used in order to maintain engine performance.

IR has been conducting trials with bio-diesel for some time now. A YDM-4 locomotive hauled the Trichi-Tanjore Passenger with a blend of 5% bio-diesel several times in July 2004 and later. Even earlier, the New Delhi - Amritsar Shatabdi Express was hauled by a 5% bio-diesel fueled locomotive on December 31, 2002 as a one-off experiment. Some other such trials are being carried out [4/04]. YDM-4 #6225 is now run by SR using a 10% biodiesel mixture, as is WDM-7 #11008. IR has plans for cultivation of the plants involved. A pilot plant capable of producting 150 liters of bio-diesel daily has been set up at the Loco Workshop in Chennai.

Q. What other alternative fuels does IR use?

Compressed Natural Gas (CNG) is another fuel that IR has experimented with. [1/05] Trials with a stationary diesel engine modified to use CNG were carried out at Shakurbasti station. More recently [5/05] two diesel railcars have been modified to run on CNG. A DEMU rake (one diesel power coach and three trailer coaches) has been modified for CNG use and has been running for several months on NR (the DEMU rake is homed at Shakurbasti shed). Seating capacity on the rake has been reduced from 384 to 354. Early trials used up to 50% CNG in the fuel mix; in the field trials the rake is running with 35% CNG. It is expected that the resulting savings in fuel costs will pay for the modifications within about 20 months of regular use. It is expected that a CNG DMU rake with 14 coaches will be run on the Delhi-Rewari line, and later on to include Shamli and Rohtak.

Also see the section on historical uses of other fuels in internal combustion engines in Indian Railways.

Q. Where can I find diagrams of locomotives?

In the UK, diagrams from major locomotive manufacturers are preserved at several libraries:

  • Mitchell Library, Glasgow (drawings from North British Locomotive)
  • University Library 'Business Archives', Glasgow (also NBL)
  • Museum of Science and Industry, Manchester (Beyer Peacock drawings)
  • National Rail Museum, York

In India, diagrams and other data are preserved at:

  • National Railway Museum, Delhi. Not many engineering drawings, but the NRM does have a large, if haphazard, collection of diagrams. Recently [4/02] a separate section called Indian Rail Archives has been set up at the NRM, with many diagrams and other material available to the public for perusal.
  • Research, Design, and Standards Organization of IR
  • Production units and major repair workshops might still have some of the engineering drawings of older locos. A personal visit to a workshop with authorization from the CME is the only way to get access to these.

It may also be possible to get information and specification sheets from manufacturers such as TELCO or BHEL directly. Overseas too, information may sometimes be obtained from manufacturers or firms that are successors to the original manufacturers. (CLW -> Bombardier, SLM -> DLM, etc.)

A diagram of a Darjeeling Himalayan Railway 'B' class loco that originally appeared in the Railway Board's Technical Bulletin No. 58 (1899 or so) has been much reprinted in DHR-related publications. Other drawings of 'B' locos are:

  • A & B class 0-4-0Ts, drawings by D. John & S. Bell. Indian Railway Study Group Newsletter, No. 6, July 1992, pp. 8-9. Great detail.
  • Roche, F.J., "Darjeeling-Himalaya(sic) Railway 0-4-0 Tank," (Class B) Railway Modeller, Vol. 8, No. 85, November 1957, p. 259. 4mm scale. These have several errors.
  • Back, N.T., "Darjeeling-Himalaya(sic) Railway Class B 0-4-OST," Model Railway News, Vol. 43, No. 508, April 1967, pp. 180-181. 7mm scale.

The Darjeeling Himalayan Railway Supporters Association of Australia (see the section on organizations) provides members a comprehensive list of DHR loco diagrams.

A primer on notations for Wheel Arrangements

Wheel arrangements and other technical design features of locomotives can be found in many sources. See, for instance, Jal Daboo's book or Hugh Hughes' books on Indian locomotives, which provide exhaustive coverage. Here, only an explanation of the general notation is provided.

Q. What do the notations such as '2-4-2' mean?

Traditionally, steam locomotives have been classified by their wheel arrangements. The system most widely used was the Whyte system. In this, the loco's leading non-powered wheels, the (usually coupled) driving wheels, and the trailing non-powered wheels are indicated separately. Indian practice (following the UK) was to count wheels and not just the axles.

Hence, ‘2-4-2’ refers to a loco with two wheels (1 axle) in the front, 4 driving (powered) wheels in the middle (2 axles) and 2 wheels (1 axle) trailing. A suffixed ‘T’ indicates a tank engine (variants include ‘ST’ for saddle tank, ‘WT’ for well tank, ‘PT’ for pannier tank, etc.). Garratts and other articulated locos are usually indicated by juxtaposing the wheel arrangements of each individual component of the compound loco: e.g., 4-8-2+2-8-4. A loco may have two or three sets of coupled powered driving axles; in which case the notation might be something like 2-8-8-2 indicating two sets of 4 driving axles each, or 2-6-6-6-2 for three sets of 3 driving axles each.

In European texts, one finds often that axles are counted, so 2-4-2 is replaced by 1-2-1, sometimes writtein 121, or even (as in France sometimes) 1B1.

Q. What does 'Bo-Bo' or 'Co-Co' mean?

Diesel and electric locos' wheel arrangements are described using a system where the axles of a loco are counted, with powered axles being described using letters and the unpowered axles (if any) indicated by digits. A set of two independently powered axles on a bogie is indicated by ‘Bo’, and a set of three independently powered axles on a bogie is indicated by ‘Co’.

Hence, a loco with two bogies, each having two separately powered axles is classified ‘Bo-Bo’; with three such bogies it would be ‘Bo-Bo-Bo’; with two bogies each with three powered axles it would be ‘Co-Co’. Sometimes locos have some leading or trailing unpowered axles too, so for instance a loco with two bogies, each having three powered axles and one unpowered one is indicated ‘1-Co-Co-1’. The ‘o’ in the powered axle description is left off to indicate that the axles are not independent, but coupled mechanically – the same motor drives all axles in the bogie (‘B-B’ instead of ‘Bo-Bo’).

A single powered axle on a bogie is indicated by ‘A’ a set of 4 powered axles is indicated ‘D’ or ‘Do’; there don't appear to be any locos in India using such arrangements, but outside India arrangements such as ‘A1A-A1A’, ‘1-D-1’, etc. have been used. A ‘+'’ may be used to separate trucks of articulated locos. Multiple unit locos are shown by parenthesizing the unit specifications and prefixing a number corresponding to the number of units, e.g., 2(1-D-1) for a 2-unit loco, each unit having one unpowered leading axle, one unpowered trailing axle, and a 4 coupled powered axles.

A primarily European variation is to use apostrophes to mark each bogie instead of using hyphens to separate them. So, "Co‘Co" is the same as "Co-Co".

Continue on to the section on notes on selected locomotive classess. Also see the section on multiple units and the section on preserved locomotives, and names of locomotives.

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