The class WDM-3A is Indian Railways' workhorse diesel-electric locomotive. Since 1993, it has been manufactured in India by the Diesel Locomotive Works (DLW), Varanasi. The model name stands for broad gauge (W), diesel (D), mixed traffic (M) engine. The WDM-3A is the most common diesel locomotive of Indian Railways. The WDM-3A is a variant of the original WDM-2C.[8] 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.[2]

The loco is now widely used across India for long distance passenger trains due to its ruggedness and high tractive loads and acceleration.


Location map of the Diesel Locomotive Sheds of Indian Railways

The first one was delivered on August 22, 1994, It was then WDM-2C.[9] More than 150 locos were produced till 1998.

Sheds that hold WDM 3A

The following loco sheds have stabled this locomotive type:[19]

Technical specifications

Technical details are as follows:[3]

ManufacturersAlco, DLW
EngineAlco 251-C, 16 cylinder, 3,300 hp (2,500 kW) (2,430 hp or 1,810 kW site rating) with Alco 710/720/?? turbo supercharged engine. 1,050 rpm max, 400 rpm idle; 228 mm × 266 mm (8.98 in × 10.47 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 1,000 rpm), fan driven by eddy current clutch (86 hp or 64 kW at 1,000 rpm)
GovernorGE 17MG8 / Woodwards 8574-650
TransmissionElectric, with BHEL TA 10102 CW alternator (1,050 rpm, 1130 V, 4,400 amperes) (Earlier used BHEL TG 10931 AZ alternator)
Traction motorsGE752 (original Alco models) (405 hp or 302 kW), BHEL 4906 BZ (AZ) (435 hp or 324 kW) and (newer) 4907 AZ (with roller bearings)
Axle load18.8 tonnes (18.5 long tons; 20.7 short tons), total weight 112.8 t (111.0 long tons; 124.3 short tons)
BogiesAlco design cast frame trimount (Co-Co) bogies
Starting TE30.45 t (29.97 long tons; 33.57 short tons), at adhesion 27%
Length over buffer beams15,862 mm (52 ft 12 in)
Distance between bogies10,516 mm (34 ft 6 in)

See also