NMR is the first mountain railway in the country that came up with the rack and pinion system. The rack and pinion system is used to cover the steep gradient the train chugs through in its journey from Mettupalayam to Udhagamandalam.

The journey starts at 1,069 ft above Mean Sea Level and travels up to a height of 7,228 ft. The rack and pinion system begins a little after Kallar station and goes up to Coonoor.

The line between Mettupalayam and Coonoor was first laid in 1898 and then it was extended up to Udhagamandalam in 1908. NMR has had Swiss x locomotives and then refurbished engines from the Golden Rock Workshop in Tiruchirapalli; it has travelled a long way from the steam fired engines using coal to the latest furnace oil fired locomotives that haul the mountain train.

In its 100 odd years of existence, the mountain railway has had its share of woes. Bridges and tracks have been washed away, landslides have disrupted its journeys and it has been considered economically unsound. But, the tracks were always restored as soon as possible after natural calamities and railway ministry or the board has always intervened to stem any talk of discontinuation of the NMR and ensure its continued services at any cost.

On Thursday, at a function organised by the Heritage Steam Chariot Trust at Udhagamandalam, founder of the trust K. Natarajan, former Chairman of the Atomic Energy Commission M.R. Srinivasan and Nilgiris District Collector P. Shankar greeted the tourists who arrived by the train and congratulated them for having chosen to travel on a day of historic significance to the NMR.

http://www.thehindu.com/todays-paper/tp-national/tp-tamilnadu/nilgiri-mountain-railway-completes-106-years/article7768035.ece