The YDM-4 is a class of

diesel locomotive A diesel locomotive is a type of railway locomotive in which the prime mover (locomotive), power source is a diesel engine. Several types of diesel locomotives have been developed, differing mainly in the means by which mechanical power is con ...

s operating on

Indian Railways Indian Railways is a state-owned enterprise that is organised as a departmental undertaking of the Ministry of Railways (India), Ministry of Railways of the Government of India and operates India's national railway system. , it manages the fou ...

. The first units were built by the

American Locomotive Company The American Locomotive Company (often shortened to ALCO, ALCo or Alco) was an American manufacturer that operated from 1901 to 1969, initially specializing in the production of locomotives but later diversifying and fabricating at various time ...

(Alco) in 1961. Since 1968, members of the class have been manufactured in India by the

Banaras Locomotive Works The Banaras Locomotive Works (BLW), formerly Diesel Locomotive Works (DLW), is a production unit of Indian Railways situated in Varanasi, Uttar Pradesh. DLW was renamed BLW in 2020. History Founded in 1956 as the ''DLW'', it manufactures locom ...

(BLW), Varanasi. The model name stands for

metre gauge Metre-gauge railways ( US: meter-gauge railways) are narrow-gauge railways with track gauge of or 1 metre. Metre gauge is used in around of tracks around the world. It was used by several European colonial powers including France, Britain and ...

(Y), diesel (D), mixed traffic (M) engine. The YDM-4 has been the most successful metre gauge diesel locomotive in India. The YDM-4 locos have a maximum speed of , restricted to . The YDM-4A is a variant of the YDM-4 that is supplied by MLW. Originally equipped with

vacuum brake The vacuum brake is a brake, braking system employed on trains and introduced in the mid-1860s. A variant, the automatic vacuum brake system, became almost universal in British train equipment and in countries influenced by British practice. Va ...

s, some were later equipped with dual brakes, particularly those working in the

Northeast Frontier Railway The Northeast Frontier Railway (abbreviated NFR) is one of the 19 railway zones of the Indian Railways. It is headquartered in Maligaon, Guwahati in the state of Assam, and responsible for operation and expansion of rail network all across N ...

History

In the mid 1950s

began introducing diesel locomotives to its metre gauge system. Metre gauge, though rare in the 21st century, used to be a dominant gauge at that time. After the introduction of YDM-1 locomotives by the

North British Locomotive Company The North British Locomotive Company (NBL, NB Loco or North British) was created in 1903 through the merger of three Glasgow locomotive manufacturing companies; Sharp, Stewart and Company (Atlas Works), Neilson, Reid and Company (Hyde Park W ...

, Indian Railway considered more powerful ones and hence General Motors Electro-Motive Division (EMD) and the

(ALCO) submitted designs of YDM-3/ YDM-5 ( 12-567C) and YDM-4 respectively for new diesel locomotives. Each company supplied 30 locomotives in 1961. While the YDM-3 was 13 tons lighter than the YDM-4, Indian Railways opted for the ALCO design because of the heavier axle load and technology agreement that would allow these locomotives to be manufactured in India. After

(BLW) completed construction of its factory in Varanasi, production of the class began in India. The initial 30 YDM-4 locomotives supplied by ALCO in 1961 were numbered between #6020 and #6049. Another batch of 8 locomotives soon followed and were numbered #6105 to #6112. YDM-4 #6113-6129 were built around 1964. Siliguri Diesel Locoshed was the first DLS to station YDM-4 locomotives in 1962. The very first YDM4, #6020, was allotted to the New Guwahati Diesel Loco Shed, which was an outbase of Siliguri DLS on 30 October 1962. YDM4 #6130 to #6198 were built by

Montreal Locomotive Works Montreal Locomotive Works (MLW) was a Canadian railway locomotive manufacturer that existed under several names from 1883 to 1985, producing both Steam locomotive, steam and diesel locomotives. For many years it was a subsidiary of the American ...

(MLW) in 1964 under the license of ALCO and were classified as YDM-4A. All the YDM-4 delivered up to then were presumably based at three premier DLS across India namely Siliguri (SGUJ), Ponmalai Goldenrock (GOC) and Sabarmati (SBI). Another batch of YDM-4A was dispatched from MLW in 1969, numbered #6259 to #6288. The first YDM-4 built by Banaras Locomotive Works (BLW) Varanasi was #6199 ''Hubli''. This loco entered service in 1968 and was dedicated to the then Deputy Prime Minister of India,

Morarji Desai Morarji Ranchhodji Desai (29 February 1896 – 10 April 1995) was an Indian politician and Indian independence activist, independence activist who served as the Prime Minister of India, prime minister of India between 1977 and 1979 leading th ...

. DLW built locos in the range #6199 to #6258. From 1969 till 1993 DLW produced YDM-4 locomotives for Indian Railways in the number range #6289 to #6769. The last YDM-4 was based at Rangapara North outbase of Siliguri DLS but later on transferred to Myanmar (Burma) Railways and possibly renumbered as DF1332.

Locomotive sheds

Technical specifications

Source:

References

External links

YDM-4 Diesel Locomotive Internals
{{Metre gauge locomotives of India, state=expanded M, Y-4 Co-Co locomotives ALCO locomotives Banaras Locomotive Works locomotives MLW locomotives Railway locomotives introduced in 1961 Metre-gauge locomotives