The Darjeeling Himalayan Railway's best-known and longest-lasting locomotive is the class B, which was built by several manufacturers from 1889 and is still in use today. Although the DHR had also procured larger locomotives and even Garratts, these small, two-axle saddle tank locomotives had apparently been best suited to the steep two-foot line with radii up to 60 feet. 

The coal capacity was later increased by planks. Due to the low quality of coal available and the cheap labor in India, the crew of these locomotives consists of up to six people. In addition to the driver, this includes two people who sit on the buffer beam and spread sand on the rails by hand. The fireman is assisted by one person who breaks the coal into equal-sized lumps and another who passes the coal to the fireman.

Locomotive Magazine, September 1918

The 34 class B members, supplied by British and American manufacturers, took on the brunt of the traffic over the decades. In 1997 they were reinforced by diesel locomotives as their number decreased due to age. Today most regular trains are pulled by the diesel locomotives, while class B mainly only takes on tourist trains. A locomotive came to the Beeches Light Railway in Great Britain around 2000, where it was used until the line closed in 2023.