pinion section of its tracks. The X Class locomotives are up to eight decades old, but the newest was completed August 2021 at the Golden Rock workshops in India. These locomotives give NMR a distinct charm, taking scores of passengers to Coonoor and Udhagamandalam, crossing , 108 curves, 16 tunnels and 250 bridges. The steam locomotives can be used on any part of the line, while the diesel locomotives can operate only on the section between Coonoor and Udagamandalam. Each diesel engine weighs a little over 50 tonnes and cost Rs. 10 crore. They have pilot and primary burners. Separate tanks hold about of diesel and of furnace oil. The hauling capacity of this new engine is . It can run at a speed of on plains and at an hour climbing a gradient. The arrival of the new engines eliminated the disruptions in service that occurred frequently. The steam locomotives are marshalled at the downhill (Mettupalayam) end of the train. The average gradient in this rack section is 1 in 24.5 (4.08%), with a maximum of 1 in 12 (8.33%). Between Coonoor and Udagamandalam, the train is operated by a YDM4 diesel locomotive using conventional rail adhesion principles. On this section, the locomotive is always at the Coonoor end of the train as although the line is not steep enough to need a rack rail, the ruling gradient out of Coonoor is steep at 1 in 25 (4%). Southern Railway carries out the majority of the locomotive repairs at the Coonoor shed but has rebuilt many of the steam locomotives at the Golden Rock Workshops. Many carriage repairs take place at Mettupalayam. Like the locomotives, major work on the carriages takes place at one of the larger railway workshops. Route The uphill journey takes around 290 minutes (4.8 hours), and the downhill journey takes 215 minutes (3.6 hours). It has the steepest track in Asia with a maximum gradient of 8.33%. During Meter Gauge era in 1990s, The Nilgiri Express used to run between Chennai(then Madras) & Udhagamandalam(then Ooty) directly. Timings were:- Madras 21.00; Ooty 10.20 & in return:- Ooty 16.30; Madras 05.50.But it was stopped after NMR got UNESCO World Heritage Tag in 1994. As of 2007, a daily train crosses the rack section, which starts from Mettupalayam at 07:10 and reaches Udhagamandalam at noon. The return train starts from Udhagamandalam at 14:00, and reaches at 17:35. The