Nilgiri Mountain Railway X class

Nilgiri Mountain Railway X class
Nilgiri Mountain Railway locomotive No.37385 preserved in the Delhi Railway Museum.
Power type	Steam
Builder	Swiss Locomotive and Machine Works, Winterthur, Switzerland (17) Golden Rock Workshop, Tiruchirapalli, India (4)
Build date	1914, 1920, 1925, 1952, 2011
Total produced	17 (21 including the four new 2011 ones)
Configuration	0-8-2T
Gauge	1,000 mm (3 ft 3 3⁄8 in)
Driver diameter	815 mm (32.09 in)
Fuel type	Coal or Oil
Fuel capacity	2011: 850 litres (190 imp gal; 220 US gal) of diesel and 2,250 litres (490 imp gal; 590 US gal) of fuel oil
Cylinders	Four, outside, compound
High-pressure cylinder size	Adhesion: 450 × 410 mm (17.72 × 16.14 in)
Low-pressure cylinder size	Rack: 450 × 430 mm (17.72 × 16.93 in)
Valve gear	Walschaerts
Top speed	Adhesion: 30 km/h (19 mph) Rack: 15 km/h (9 mph)

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. All cylinders are outside the locomotive's frames. The two low-pressure cylinders drive the rack wheels. These cylinders are positioned above the two main high-pressure cylinders, which drive the main wheels.

Engines of this class were first brought as replacements for the line's original Beyer-Peacock 2-4-0 engines whose traction power was too weak for the traffic. The X class locos were bought in two batches from the Swiss Locomotive and Machine Works, Winterthur, Switzerland. The first batch (12-nos.) were brought into operation over the years between 1920 and 1925 and the newer batch (5-nos.) in 1952.

Table of SLM orders

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

Replacements

Four new oil-fired steam locomotives have been ordered to replace or ease the load on the existing X class locomotives. They too will be of basically the same design as the existing locomotives and are also described as being of the X Class. The first of these, No. X 37396, arrived in Feb 2011, and entered service on March 24, 2011. The second oil fired steam engine, No. X 37397, with a welded boiler used for the first time, was rolled out at Golden Rock in Feb. 2012, and is to enter service on NMR in March 2012.

Conversion to oil

Nilgiri Mountain Railway locomotive No.37395 at Coonor Shed, February 2005

One locomotive, No. 37395, was modified changing it from coal to oil-fired in 2002, another has been modified and the Railway is looking to retro-fit further locomotives to oil-firing. Conversion of coal into oil-fired system has the potential to reduce the danger of forest fires that could be caused by embers flying out from the locomotive. Additionally, the effort involved in the manual lifting of coal and putting it into the boiler is eliminated. The current oil-fired locomotives need only one fireman to accompany the driver, while coal-fired engines need two firemen. However, X 37395 was reconverted to coal-burner in August 2009 for unknown reasons.

References

• Hughes, Hugh (1992). Indian Locomotives, Part 2 – Metre Gauge 1872–1940. Harrow, Middlesex: Continental Railway Circle. ISBN 0-9503469-9-3. 
• Hughes, Hugh (1996). Indian Locomotives, Part 4 – 1941–1990. Harrow, Middlesex: Continental Railway Circle. ISBN 0-9521655-1-1.