Indian locomotive class WDM-3A

The Indian locomotive class WDM-3A is a class of diesel-electric locomotive that was developed in 1993 by Diesel Locomotive Works (DLW), Varanasi for Indian Railways. The model name stands for broad gauge (W), Diesel (D), Mixed traffic (M) engine, with 3300 horsepower (3A). The WDM-3A is a later classification of earlier WDM-2C. They entered service in 1994. A total of 143+ WDM-3A was built at ALCO and Diesel Locomotive Works (DLW), Varanasi between 1994 and 2003 with rest of the 1246 units being rebuild from WDM-2 which made them the most numerous class of mainline diesel locomotive until the WDG-4.

WDM-3A of Vatva loco shed
Type and origin
Power typeDiesel
BuilderDLW, Diesel Loco Modernisation Works
ModelALCO DL560C variant
Build dateAugust 22, 1994, onwards
Total producedWDM-3A: 1402 as of December 2015
RebuilderDiesel-Loco Modernisation Works, Patiala
 • UICCo-Co
Gauge1,676 mm (5 ft 6 in)
BogiesALCO Asymmetric cast frame trimount
Wheel diameter1,092 mm (3 ft 7 in)
Wheelbase12.834 m (42 ft 1 14 in)
Length17.12 m (56 ft 2 in)
Width2.864 m (9 ft 4 34 in)
Height4.185 m (13 ft 8 34 in)
Axle load18,800 kg (41,400 lb)
Loco weight112.8 t (111.0 long tons; 124.3 short tons)
Fuel typeDiesel
Fuel capacity5,000 L (1,100 imp gal; 1,300 US gal)
Prime moverALCO 251-C
RPM range400 - 1050 rpm
Engine typeV16 Diesel engine
AspirationABB VTC304-15 or Napier NA 295 IR turbocharger
Traction motorsBHEL TA 10102 CW (new), BHEL TG 10931 AZ(old)
Cylinder size228 mm × 266 mm (8.98 in × 10.47 in)
bore x stroke
TransmissionDiesel electric
MU working2
Train brakesAir, Vacuum and Dual
Performance figures
Maximum speed120 km/h (75 mph)
Power outputWDM-3A: 3100 HP, WDM-3D: 3300 HP, WDM-3E: 3500 HP,WDM3F: 3600 HP.
Tractive effort30.45 t (30 long tons; 34 short tons)
Factor of adh.0.27
OperatorsIndian Railways
Numbers13xx,14001-14057, 14058-14143, 16000-, few in 18xxx series and 17xxx series
NicknamesCheetah, Prabal, Velociti, Awadh, Firex, Sher Punjab, Veer
LocaleAll over Indian Railways

The WDM-3A is one of the most successful locomotives of Indian Railways serving both passenger and freight trains for over 26 years. A few WDM-3A units were exported to neighboring countries like Sri Lanka and Bangladesh. Despite the introduction of more modern types of locomotives like WDG-4 and electrification, a significant number are still in use, both in mainline and departmental duties. As of 2020, 1081 locomotives still retain "operational status" on the mainline as WDM-3A, with further examples having been converted back to WDM-2 or WDM-2S. The loco is now widely used across India for long-distance passenger trains due to its ruggedness and high tractive loads and acceleration.


WDM3A with Padatik Express
WDM3A VTA Shunting in Rajkot
A WDM-3A Loco from Gooty Loco Shed hauling an Express train

The first one was delivered on August 22, 1994, It was then WDM-2C.[1][2] First 57 units produced till March 1996 (Indian Railway road number 14001-14057) had rounded front hood profile similar to contemporary newer classes of locos built by DLW (WDG3A and WDP1). After that there was a gap of long four years in the WDM3A production line in DLW. These units have been retro-fitted with dual brakes, in addition to the air and vacuum brakes. The WDM-3A locos have a maximum speed of 120 km/h (75 mph). The gear ratio is 65:18.[3] These new locomotives had their control stand shifted to the left side of the cabin. Meanwhile, Diesel Loco Modernization Works (erstwhile Diesel Modification Works which again was known as Diesel Component Works) in Patiala started rebuilding the existing WDM2 locomotives, which had reached midlife, with upgraded power-packs. DLMW Patiala re-calibrates the power-pack and upgrades the output power rating to 3100HP.[4] DLW again started building WDM3A from the year 2000 and continued till the end of 2002 with locomotive road numbers in the range 14058–14143. All the locomotives rebuilt by DLMW and later batch from DLW had regular WDM2 type square short hood profile and control stand position. DLW again built WDM3A variant locomotives, during 2005–2006, in the road number range 14144-14167 which were classified as WDM3B due to their difference in bogie design from classic ALCo asymmetrical trimount to HAHS design which was employed in WDG2 and later WDM3D classes too. Most of the WDM3B were later converted to WDM3D. In 2011, DLMW rebuilt locomotive number 16502 as WDM3A and equipped it with an Electronic Fuel Injection (EFI) system jointly developed by Engine Research Laboratory of IIT Kanpur, Engine Development Directorate of RDSO, and DLMW Patiala.[5] DLMW continues to rebuild WDM2 as WDM3A and recently they have started rebuilding the DLW built WDM3A too when they reach their midlife. Recent rebuilt locomotives are rated at 3300 HP, and from 2009 onward they are equipped with Daulat Ram DBR, and since 2014 they are also equipped with an Auxiliary Power Unit (APU) in the short hood.[6] Some rebuilt locomotives have Co-Co-fabricated ATHS (Advanced Trimount High Speed) bogies instead of ALCo cast-iron type.[7] All the rebuilt WDM3A bear the "-R" suffix to their road numbers.

In 2012 Bangladesh Railway ordered 26 WDM3A from DLW. They are classified as Class 6500 there. These units, however, lack the dynamic braking which happens to be an essential component in their Indian counterparts.

Sub ClassesEdit


The WDM-3C were just upgraded and more powerful WDM3As with the ALCO engine gain rebuilt to output 3300 hp. It was the first follow-up experiment after the WDM-3A to squeeze more power out of the ALCO engine, an intermediary that would later lead to the development of the WDM-3D. Not many were produced, all of which were rebuilds of the WDM2 or WDM3A and were identical to the previous variants in every aspect. They can no longer be found over the railway network as all of them have been rebuilt into the WDM-3A or WDM-2 type.[8]

Locomotive shedsEdit

Zone Name Shed Code Quantity
Central Railway Pune PA 11
Kurla CLA 2
Eastern Railway Howrah HWH 9
Bardhaman BWN 50
Andal UDL 8
Jamalpur JMP 28
East Central Railway Patratu PTRU 17
Mughalsarai MGS 20
Samastipur SPJ 32
East Coast Railway Visakhapatnam VSKP 36
Northern Railway Tughlakabad TKD 34
Ludhiana LDH 105
Lucknow LKO 25
North Central Railway Jhansi JHS 32
North Eastern Railway Gonda GD 99
Northeast Frontier Railway Malda Town MLDT 58
Guwahati NGC 15
North Western Railway Abu Road ABR 68
Southern Railway Erode ED 4
Ernakulam ERS 34
Golden Rock GOC 11
Tondiarpet TNP 20
South Central Railway Kazipet KZJ 12
Gooty GY 7
Guntakal GTL 22
Moula Ali MLY 18
South Eastern Railway Kharagpur KGP 31
Bondamunda BNDM 29
Bokaro Steel City BKSC 19
South East Central Railway Raipur R 26
South Western Railway Krishnarajapuram KJM 22
Western Railway Ratlam RTM 24
Vatva VTA 34
West Central Railway Itarsi ET 56
New Katni Junction KTE 47
Total Locomotives Active as of 01-08-2020[9] 1065

Technical specificationsEdit

Technical details are as follows:[10][11]

Manufacturers DLW, DLMW (DMW/DCW)
Engine Alco 251-C, 16 cylinder, 3,300 hp (2,500 kW), earlier 3,100 hp (2,300 kW) (3,007 hp or 2,242 kW site rating, earlier 2,900 hp (2,200 kW)) with Napier NA2951R/ ABB VTC-304-VG15/ GE 7s 1716 turbo supercharged engine. 1,050 rpm max, 400 rpm idle; 228.6 mm × 266.7 mm (9.00 in × 10.50 in) bore x stroke; compression ratio 12.5:1. Direct fuel injection, centrifugal pump cooling system (2,457 L/min (540 imp gal/min; 649 US gal/min) at 1,050 rpm), fan driven by eddy current clutch (90 hp or 67 kW at 1,050 rpm)
Governor EDC / Woodward 8574-650
Transmission Electric, with BHEL TA 10102 CW alternator (1,050 rpm, 1100 V, 4,400 amperes) (Earlier used BHEL TG 10931 AZ alternator)
Traction motors BHEL TM 4906 AZ/ 4907 BZ (435 hp or 324 kW) (with roller bearings)
Axle load 18.8 tonnes (18.5 long tons; 20.7 short tons), total weight 112.8 t (111.0 long tons; 124.3 short tons)
Bogies Alco design cast frame asymmetric trimount (Co-Co) bogies
Starting TE 30.45 t (29.97 long tons; 33.57 short tons) at adhesion 27%, continuous 28.05 t (27.61 long tons; 30.92 short tons)
Length over buffer beams 15,862 mm (52 ft 12 in)
Distance between bogies 10,516 mm (34 ft 6 in)

See alsoEdit


  1. ^ "IR History: Part - V (1970-1995)". Indian Railways Fan Club. Retrieved 22 August 2017.
  2. ^ Agarwal, Avinash Kumal; Dhar, Atul; Gautam, Anirudh; Pandey, Ashok, eds. (2017). Locomotives and Rail Road Transportation - Technology, Challenges and Prospects. Springer. p. 16. ISBN 978-981-10-3787-0. LCCN 2017930134 – via Google Books.
  3. ^ "About WDM-3A". Indian Railways Fan Club.
  4. ^ (PDF). Indian Railways Retrieved 2 March 2018. Missing or empty |title= (help)
  5. ^ "Direction Article Development of EFI for 204-stroke locomotive diesel engine" (PDF). Indian Railways. 2018. Retrieved 2 March 2018.
  6. ^ "Company Profile" (PDF). Indian Railways. Retrieved 2 March 2018.
  7. ^ "Motive Power" (PDF). RDSO. 2018. Retrieved 2 March 2018.
  8. ^ "Diesel Loco Roaster WDM(ALCO) series".
  9. ^ "Railway Website Mechanical Department". Retrieved 16 May 2020.
  10. ^ "Diesel Locomotive Classes – Broad Gauge". Indian Railways Fan Club.
  11. ^ "Diagram Book of WDM2C Locomotive" (PDF). RDSO.