Indian locomotive class YDM-4

The YDM-4 is a metre gauge diesel locomotive class of Indian Railways, with the letters standing for metre gauge, diesel and mixed traffic engine. The first units were built by the American Locomotive Company in 1961, after Indian Railways compared designs from Alco and from General Motors Electro-Motive Division and chose the Alco model for its heavier axle load and for a technology agreement that would let the locomotives be made in India. Once the Banaras Locomotive Works at Varanasi finished its factory, the first locally built unit, number 6199 Hubli, entered service in 1968 and was dedicated to Morarji Desai, then Deputy Prime Minister. The works went on producing the class from 1969 to 1993, in the number range 6289 to 6769, while Montreal Locomotive Works supplied a licensed variant classed YDM-4A. The article calls it the most successful metre gauge diesel locomotive in India, with a maximum speed of 100 km/h, and records the last unit being transferred to Myanmar Railways.