'X' Class locomotives (Nilgiri Mountain Railway)

Nilgiri Mountain Railway X class
Black locomotive with a blue cab
Nilgiri Mountain Railway locomotive No.37385, preserved in the Delhi Railway Museum
Type and origin
Power typeSteam
BuilderSwiss Locomotive and Machine Works, Winterthur, Switzerland (17)
Golden Rock Railway Workshop, Golden Rock, Tiruchirappalli, India (4)
Build date1914, 1920, 1925, 1952, 2011-2014
Total produced21
 • Whyte0-8-2T
Gauge1,000 mm (3 ft 3 38 in) metre gauge
Driver dia.815 mm (32.09 in)
Fuel typeCoal or fuel oil
Fuel capacity2011: 850 litres (190 imp gal; 220 US gal) of diesel and 2,250 litres (490 imp gal; 590 US gal) of fuel oil
CylindersFour, outside, compound
High-pressure cylinderAdhesion: 450 mm × 410 mm (17.72 in × 16.14 in)
Low-pressure cylinderRack: 450 mm × 430 mm (17.72 in × 16.93 in)
Valve gearWalschaerts
Performance figures
Maximum speedAdhesion: 30 km/h (19 mph)
Rack: 15 km/h (9 mph)

X class locomotives are metre gauge 0-8-2T rack and pinion compound locomotives on the Nilgiri Mountain Railway in the Nilgiri Hills of southern India. They are used on the 28-kilometre-long (17 mi) section between Coonoor and Mettupalayam, where the steepest gradient is 1 in 12.5. The railway uses the Abt system on these steep sections. The locomotives have two high-pressure and two low-pressure cylinders, located outside the locomotive's frames. The low-pressure cylinders drive the rack wheels, and are positioned above the two main high-pressure cylinders which drive the main wheels.

This class of engine was acquired to replace the line's original Beyer-Peacock 2-4-0 engines, which were not powerful enough to handle the traffic.[1][2] The X-class locomotives were bought in two batches from the Swiss Locomotive and Machine Works, Winterthur, Switzerland. The first batch of 12 was delivered between 1920 and 1925, and the second batch of five was delivered in 1952.[1][3] Four more members of the class were built in India between 2011 and 2014.

SLM orders[]

SLM orders[4][5]
SLM Works Nos. Year Quantity NMR No. All India No. Notes
2456–2459, 2469–2470 1914 6 1–6 37384 ex-No. 1
2734–2736, 2733 1920 4 7–10 37385–37388
3000–3001 1925 2 11–12 37389–37390
4069–4073 1952 5 13–17 37391–37395
unknown 2011 - 2014 4 18-21 37396-37399 Non-SLM

Conversion to oil[]

Black-and-blue locomotive, converted from coal to oil firing
Locomotive No.37395 at Coonoor Shed, February 2005

The coal-fired Locomotive No. 37395 was modified to oil firing in 2002, and another locomotive was similarly modified shortly afterwards. The railway intends to convert more locomotives to oil-fired system, since they are less likely to spark forest fires and are easier to refuel. Unlike coal-fired engines which require two firemen, only one fireman needs to travel with the driver of an oil-fired locomotive.[6][7]

New locomotives[]

To ease the load on existing X-class locomotives, four oil-fired X-Class 0-8-2T rack and pinion compound engine steam locomotives with a similar design were ordered. The first one (No. X 37396) arrived in February 2011 and entered service on March 24 of that year. The second one (X 37397) was rolled out at the Golden Rock Railway Workshop in February 2012, and entered service on the railway in March. The third one built by Golden Rock, Trichy (X 37398), entered service in March 2013. The fourth (X 37399) was rolled out on March 5, 2014 at the Central Workshop in Ponmalai, Tiruchirapalli, to join the fleet after trials on the railway.

In fiction[]

Ashima, a character based on the X Class and voiced by Tina Desai, appears in the 2016 animated film Thomas & Friends: The Great Race. She also appears in the twenty-second series and the twenty-third series of Thomas & Friends. [8][9][10]



  1. ^ a b Bhandari, R. R. (2008). "Steam in history". IRFCA. Retrieved 2 March 2010.
  2. ^ "Blue Mountain Railway". India for Visitors. indiaforvisitors.com. 2003. Retrieved 2 March 2010.
  3. ^ "National Railway Museum". Rail in India. Retrieved 2 March 2010.
  4. ^ Hughes 1992, p. 98
  5. ^ Hughes 1996, p. 58
  6. ^ Rajaram, R. (21 December 2009). "Work for manufacturing four new oil-fired steam locos begins". The Hindu. Chennai, India: The Hindu Group. Archived from the original on 31 December 2009.
  7. ^ "Oil fired Steam engine on Nilagiri Railway , India". Encyclopedia.com. HighBeam. 2009. Retrieved 2 March 2010.
  8. ^ "Meet Ashima, and Her Impact on Child Product Sales to India". India Briefing. March 31, 2016. Archived from the original on December 7, 2016. Retrieved July 13, 2017.
  9. ^ "Ashima - Character Profile & Bio". Thomas & Friends - Official Website. Retrieved August 26, 2017.
  10. ^ "Flying Scotsman on track to star in new 'more diverse' Thomas the Tank Engine film". ITV News. April 6, 2016. Archived from the original on August 11, 2016. Retrieved July 13, 2017.


  • Hughes, Hugh (1992). Indian Locomotives, Part 2 – Metre Gauge 1872–1940. Harrow, Middlesex: Continental Railway Circle. ISBN 978-0-9503469-9-1.CS1 maint: ref=harv (link)
  • Hughes, Hugh (1996). Indian Locomotives, Part 4 – 1941–1990. Harrow, Middlesex: Continental Railway Circle. ISBN 978-0-9521655-1-4.CS1 maint: ref=harv (link)

External links[]

Media related to Nilgiri Mountain Railway class X at Wikimedia Commons