Nilgiri Mountain Railway X class
 The X class locomotives are a class of metre gauge 0-8-2T rack and pinion compound locomotives working on the Nilgiri Mountain Railway in the Nilgiri Hills of southern India. They are used on the 20 km section between Coonoor and Kallar where the gradient of the track can be as steep as 1 in 12.5. At these steep sections the railway uses the Abt system. The X class locomotives are compound locomotives with two high-pressure and two low-pressure cylinders.