Locomotives were introduced for underground operation in coal mines in the early 1930s but their use did not become widespread until after the 1939-1945 war. The first diesel powered locomotive with a flameproof engine was introduced in 1939 following its approval by the Mines Department in conjunction with the Safety in Mines Research Board. To learn more about underground locomotive haulage, click here to download the PDF.
Thanks for the share, PMJ!