Rolling stock An X Class Steam Locomotive A YDM 4 Biodiesel Locomotive NMR uses 'X' Class steam rack locomotives, manufactured by the Swiss Locomotive and Machine Works of Winterthur in Switzerland. In 1854, first plans w the rack and pinion section of its tracks. The X Class locomotives are six to eight decades old. These locomotives give NMR a distinct charm, taking scores of passengers to Coonoor and Udhagamandalam, crossing 45.8 kilometres (28 mi), 108 curves, 16 tunnels and 250 bridges.