The WDM-7 is a diesel–electric locomotive of Indian Railways. It has been manufactured by Banaras Locomotive Works (BLW), Varanasi. The model name stands for broad gauge (W), diesel (D), mixed traffic (M) 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 (road numbers #11001 to #11015) 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 (#11008) has been modified to run on bio-diesel.
These Co-Co diesel-electric locomotives were designed primarily for branch-line duties (top speed 105 km/h). 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 (the latter produces 2600 hp of usable power, as opposed to the WDM-7 which produces 2000 hp). 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 in March 2025.https://indianrailways.gov.in/railwayboard/uploads/directorate/mec_engg/2025/Availability%20target%20March%202025.pdf As of November 2025, a single unit out of the 15 locomotives built is still in service.
Locomotive shed Zone Name Shed Code QuantitySRGolden RockGOC1Total Locomotives Active as of November 2025 1
Former Ernakulam Erode Tondiarpet
Preserved examples A single WDM-7 locomotive has been earmarked for preservation by IR. ClassManufacturerLoco NumberPrevious shedNameLiveryLocationrefWDM-7BLW11001Golden Rock (GOC)TNP blue/dark blue/blueEarmarked for preservation: I.R. Heritage Website [November 2018]
See also Indian locomotive class WDM-2 List of diesel locomotives of India Rail transport in India Rail transport in India#History
References Notes
Bibliography
External links
Ministry of Railways (Railway Board) [IRFCA] Indian Railways Locomotive Roster Changes