Indian locomotive class WDM-7

The WDM-7 is a diesel–electric locomotive of Indian Railways. It has been manufactured by Banaras Locomotive Works, Varanasi. The model name stands for broad gauge (W), diesel, mixed traffic engine.
These units have been retro-fitted with air brakes, in addition to the original vacuum brakes. The WDM-7 locos have a maximum speed of, restricted to when run long hood forward - the gear ratio is 94:17.

History

Fifteen of these locomotives were built from 1987 to 1989 as a low-powered, “lightweight” version of the original ALCO. Like the WDM-6, the IR wanted a lower powered locomotive to handle small rake local and passenger services. However, all sheds declined them and they ended up at Ernakulam where they were used to handle local and shuttle services with good degrees of efficiency. Becoming aware of their abilities, the Southern Railway moved all the WDM-7s out of Ernakulam to Tondiarpet, where they are housed there as of 2023. These days, they are seen being used as shunters at Chennai Central or for light passenger haulage. One has been modified to run on bio-diesel.
These Co-Co diesel-electric locomotives were designed primarily for branch-line duties. They have two 3-axle bogies. The power-pack is a 12-cylinder Alco 251B unit. They are a lower-powered variant of the WDM-2. They were formerly housed at Erode and Ernakulam as well. They are reliable and rugged locomotives even though low-powered. They can be easily recognised by the lack of grilles on the short hood; in fact, they look exactly the same as the WDM-2 except for the “clean” short-hood-forward nose without grilles. Two locos operated on a mixture of bio-diesel and diesel. Retirement and scrapping of these locomotives began on March 2025. As of November 2025, a single unit out of the 15 locomotives built is still in service.

Locomotive shed

Former

Preserved examples

A single WDM-7 locomotive has been earmarked for preservation by IR.

Class	Manufacturer	Loco Number	Previous shed	Name	Livery	Location	ref
WDM-7	BLW	11001	Golden Rock		TNP blue/dark blue/blue	Earmarked for preservation: I.R. Heritage Website