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Broad Gauge Diesel Locomotives

 

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 (double-headed by WDM-1's before WDM-2's and WDM-4's were introduced). Most of the WDM-1 locos had Co-Co 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all in SER, based at Bondamunda and perhaps some at Waltair and relegated to shunting or piloting duties as they were withdrawn / condemned.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 Today all have been withdrawn.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).

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 WDM-2S 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 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. specifications.

Following the new mainline diesel classification scheme, new WDM-2C's converted or overhauled by DCW, Patiala, are being labelled WDM-3A

WDM-2D There are a few WDM-2D units in ER used for push-pull operations (Sealdah-Hasnabad, 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.

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.

WDM–3DA higher-powered version of the basic WDM-2C (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 'DM-3D-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.

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.

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. They have been spotted with conventional dynamic brake equipment.

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 turbo-supercharged 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.

All are now decommissioned [7/00]. About 20 are at Mughalsarai shed [7/01], and the rest at Alambagh stores depot destined for scrapping. One (#18001, second of class) is now [2/01] at the NRM. IR numbers 18000-39, 18080-111. Interestingly, the gap in serial numbers corresponds to the 40 units of this model delivered by GM to Pakistan at the same time. Four units (18004, 18022, 18098, and 18107) were purchased by IRCON in 2000, and sent to Bangladesh for construction work. 

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 YDM-4 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.

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 power-pack 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.

WDP–1 (Class name carried over from old system.) A poor adaptation of the WDM-2 intended for hauling commuter trains with small numbers of coaches, this model never performed well and has always had a lot of ride quality and maintenance problems. With a 12-cylinder engine and low overall weight, the decision was made to use a Bo-Bo wheelset for it, unsual for IR diesels. These locos have a left-hand driving position in the cab and thus are often manned by a single driver when working long hood forward (the left-hand position enables easy token collection by the driver). Homed at Tughlakabad and Vijaywada. Used mostly for ordinary passenger trains.

Rated at 2300hp. Bo-Bo fabricated bogies. Produced from April 1995, last loco on March 26, 1999. WDP-1 locos are excepted from the new mainline diesel classification scheme and will remain known as WDP-1 and not WDP-2C or some such.

WDP–2(Class name carried over from old system, new name WDP-3A.) New 3100hp dedicated passenger diesel loco. Twin full-forward cabs, streamlined design, Alco 251-C V-16 power unit, with an ABB/GE turbo supercharger and provided with an electronic governor to control the engine's power output.

The first one, #15501, rolled out in October 1998. Used on KR (e.g., Trivandrum Rajdhani) ,some SR sections [8/00] (Chennai Egmore - Kanyakumari) and NR. Rated top speed is 160km/h (in both directions). Two-stage suspension with Flexicoil Mark IV fabricated bogies (Co-Co). Air-braked. The WDP-2A variant is essentially the same, but with dual brakes. The new class name for these is WDP-3A.

WDP–3(Class name carried over from old system.) Prototype design with WDP-1 power-pack and Co-Co wheelset; never entered serial production. (1996) It's not clear how widely the class name 'WDP-3' was applied to this design, since it never entered service, but some documents refer to it in this way and we have followed that practice since this prototype design fills an otherwise empty slot in the WDP series. (However, note that WDP-3A is the new class name for what used to be known as the WDP-2.

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 turbo-supercharged 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.

All are now decommissioned [7/00]. About 20 are at Mughalsarai shed [7/01], and the rest at Alambagh stores depot destined for scrapping. One (#18001, second of class) is now [2/01] at the NRM. IR numbers 18000-39, 18080-111. Interestingly, the gap in serial numbers corresponds to the 40 units of this model delivered by GM to Pakistan at the same time. Four units (18004, 18022, 18098, and 18107) were purchased by IRCON in 2000, and sent to Bangladesh for construction work. 

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 YDM-4 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.

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 power-pack 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.

WDP–1 (Class name carried over from old system.) A poor adaptation of the WDM-2 intended for hauling commuter trains with small numbers of coaches, this model never performed well and has always had a lot of ride quality and maintenance problems. With a 12-cylinder engine and low overall weight, the decision was made to use a Bo-Bo wheelset for it, unsual for IR diesels. These locos have a left-hand driving position in the cab and thus are often manned by a single driver when working long hood forward (the left-hand position enables easy token collection by the driver). Homed at Tughlakabad and Vijaywada. Used mostly for ordinary passenger trains.

Rated at 2300hp. Bo-Bo fabricated bogies. Produced from April 1995, last loco on March 26, 1999. WDP-1 locos are excepted from the new mainline diesel classification scheme and will remain known as WDP-1 and not WDP-2C or some such.

WDP–2(Class name carried over from old system, new name WDP-3A.) New 3100hp dedicated passenger diesel loco. Twin full-forward cabs, streamlined design, Alco 251-C V-16 power unit, with an ABB/GE turbo supercharger and provided with an electronic governor to control the engine's power output.

The first one, #15501, rolled out in October 1998. Used on KR (e.g., Trivandrum Rajdhani) ,some SR sections [8/00] (Chennai Egmore - Kanyakumari) and NR. Rated top speed is 160km/h (in both directions). Two-stage suspension with Flexicoil Mark IV fabricated bogies (Co-Co). Air-braked. The WDP-2A variant is essentially the same, but with dual brakes. The new class name for these is WDP-3A.

WDP–3(Class name carried over from old system.) Prototype design with WDP-1 power-pack and Co-Co wheelset; never entered serial production. (1996) It's not clear how widely the class name 'WDP-3' was applied to this design, since it never entered service, but some documents refer to it in this way and we have followed that practice since this prototype design fills an otherwise empty slot in the WDP series. (However, note that WDP-3A is the new class name for what used to be known as the WDP-2.

WDP–4These are GM EMD GT46PAC locos. Starting in June 2001, 10 of them (#20000 to #20009) were provided by GM, operating out of Hubli (but frequently seen at Guntakal, Gooty, Bangalore and Secunderabad). In April 2002 DLW started producing these locomotives with 20011, 20013 and 20014 being assembled from completely knocked down kits. 20012 was the first indigenously manufactured WDP-4 and features a modified fibre glass shell over the standard cab. DLW had plans only for these 5 in its first production batch, but started to produce them in large numbers starting in late 2003.

These are 4000hp locos with the 16-cylinder EMD 16-710 (16-V-710G3B-EC) turbocharged engines (AC-AC transmission) with unit fuel injection. The fabricated underframe has a rigid design. The bogies are GM's light-weight cast HTSC bogies similar to those of WDG-4 locos but meant for passenger use. (See the WDG-4 notes for some more information.) The bogies are said to have a 'million mile' overhaul interval because of a reduction in the number of wearing surfaces. The suspension is a two-stage suspension. They have an interesting Bo1-1Bo wheel arrangement. At 119t they are 7t lighter than the WDG-4 because they have 2 fewer traction motors. Max. speed 160km/h, although in trials it is said to have been run at speeds up to 180km/h. However, in most cases today [2/05] the loco is restricted to 110km/h or so since it used for hauling heavier 24-coach passenger trains. Factor of adhesion is claimed to be around 32% (all-weather). The EM2000 onboard microprocessor system provides a flexible and expandable control system with complete self-diagnostic and unit history features. The cab body is made of fibreglass. It is expected that these will need to return to their home sheds only once in about 90 days for regular maintenance. However, the links at Hubli [1/05] are such that these end up being 'home' every 15 days in any case. Indigenization has proceeded well with many components being made in India now: motors by Crompton, alternators by Kirloskar, etc.

Unusually for IR locos, the DLW-built WDP-4's have cab air-conditioning factory-installed. However, the Hubli shed apparently discourages the use of the air-conditioning equipment for fear it affects fuel consumption adversely [10/04].

Starting in April 2005, these locos were allocated in large numbers to Krishnarajpuram shed of the SWR with Siliguri in the NFR receiving a few locos in late 2006. [12/08] More sheds are expected to home these locos, but currently, along with Hubli, these are the only sheds that handle this class. The current holding of all sheds combined is 75+.

#20040 homed at KJM shed is the first IGBT based WDP-4. The traction conversion system was supplied by Siemens.

WDP–4B These locos are modified versions of the WDG-4 class locos, used for passenger operations. They have a reduced axle load of 20.2t (compared to the WDG-4's 21t axle load), achieved mainly by trimming the weight of the underframe. The gear ratio is 17:77, horsepower rating of 4500hp (brake horsepower 4150hp), and the maximum tractive effort is 384.4kN. It has an operational design speed of 130km/h and a maximum speed of 150km/h. All other features are essentially the same as with the WDG-4. Please see the WDG-4 class information for more details on this loco.

Initially two prototypes of the WDP-4B class were built using components for the WDP-4 class loco were built (#20047, #20075 - in the number series for the WDP-4 class). Serial production of these locos began in March 2010.

Note that although the class designation makes it seem like a minor variant of the WDP-4 class, it has significant differences from it, being much closer to the WDG-4 class. In particular, the WDP-4 has 4 PAC traction motors (Bo-Bo) whereas the WDP-4B has 6 traction motors (Co-Co). In addition, the traction motors have individual inverters, so that in the case of one inverter failing, 5 traction motors are still available, allowing the loco to reach its destination under reduced power. The WDP-4B also has a provision for an inverter-driven head-end power unit, allowing running trains without a generating car (EOG) for hotel power. 

WDG–1 Non-existent!! :-) There does not appear to have been a WDG-1 class; Jal Daboo's book and some other documents refer to such a loco class, but that class is what was later classified as the WDG-4. (There was originally no WDG-3 either, in the old classification scheme. But with the new classification scheme there are of course new classes in the WDG-3 series.)

WDG-3A / WDG–2(Old class name was WDG-2, new class name is WDG-3A.) This 3100hp model was developed in response to problem areas noted with the WDM-2, such as ride quality, lateral oscillations, and poor traction with heavy loads. Power-pack is the same as that of the WDP-2.

First loco delivered on July 18, 1995. A WDG-3A / WDG-2 can haul about 3000 tonnes on ordinary gradients. Shares bogie design with WCAG-1, WCAM-3, WAG-7 (high-adhesion trucks). They are the most common goods locos seen on KR. The gear ratio is 74:18. Most of these are air-braked, but some (e.g., at Pune) are being retrofitted with vacuum brakes to make them dual-braked to handle the vacuum-braked freight stock (TP, TK petroleum tankers between Loni petrol depot and Miraj; some BCX rakes, etc.).

Balancing speed of 69km/h with a 58 BOXN wagon load. Max. speed 100km/h. The WDG-2A variants are dual-braked. Some older WDG-3A units were made with left-hand-side driving position in the cab. [7/02] Newer units of the class are being fitted with microprocessor governors. The first of these variants, Garuda (#14951) is at Gooty. One WDG-3A, #14944 at Erode, has an air-conditioned cabin.

• Builders: DLW
• Engine: Alco 251C-16 upgraded by DLW, 3100hp. 1050rpm max / 400rpm idle. Fuel injection, cooling, fan, bore/stroke as with WDM-2C. Compression ratio 12.5:1. NAP NA2951R or ABB VTC304-15 turbo-supercharger.

WDG–3B : A few locos are known to carry this class marking (4 units at at Gooty [2/05] in a distinctive blue-cream livery, some seen around Bangalore too). Thought to be an upgraded version of the WDG-2 (WDG-3A), but details are not known. Numbered in the #149xx range.

WDG–4 New dedicated goods diesel locos. These are GM's GT46MAC models. First units were imported in 1999 (13 fully built, 8 in kit form). Now [4/02] DLW has begun local production; 3 have been built and a further 25 or so were built in 2002. As of [1/06] 60+ units have been built.

The loco shed at Hubli has been modified to handle these; initially all will be based at Hubli and will be used to haul mineral ore freight from Bellary or Hospet to Vasco da Gama.

The locos are rated at 4000hp and use 3-phase AC traction motors. They can start a load of 58 BOXN wagons on a 1 in 150 grade and have a balancing speed of 85km/h for such a load on level track. Max. speed is 100km/h. They can be MU'd with up to 4 units operating in tandem. Gear ratio 85:16. Axle load 21 tonnes. They have an evaporation-bath-cooled converter system, and the Siemens SIBAS 16 traction control system. The locos also have slip-control mechanisms.

They are expected to have lower maintenance costs, as they need to return to the home shed only once in 90 days instead of every 7-10 days as with the earlier diesels. Fuel costs are also about 20% lower than with the WDM-2. [1/05] Earlier plans to home more of these at Golden Rock seem to have been dropped; instead more are expected to go to the northeast (Siliguri? New Alipurduar?).

The first units from GM were #12001-12013 manufactured between 7/97 and 9/98; followed by a second order (#12014-12021) manufactured around 12/98. The first unit, #12001, has been seen often [1/05] in a green-black livery with no IR markings and instead '9001 / General Motors' painted on it.