Sri Lanka Railways M1

The M1 locomotive was a class of locomotives, used by Sri Lanka Railways, imported from 1953, and manufactured by Brush Bagnall Traction.

Sri Lanka Railways class M1
M1 No.560
Type and origin
Power typeDiesel-electric
BuilderBrush Bagnall Traction
Serial number3025–3049[1]
Build date1952[1]
Total produced25[1]
Gauge5 ft 6 in (1,676 mm)
Loco weight88 long tons (89 t; 99 short tons)
Fuel typeDiesel
Prime moverMirlees JS12VT[2]
Engine typeV12, 4 stroke diesel[2]
Performance figures
Power output1,000 hp (746 kW)
OperatorsCeylon Government Railway
» Sri Lanka Railways
First run1953–1956
Sources:[3] except where noted

The locomotives weighed 88 long tons (89 t) had a 1,000 hp (746 kW) V12 Mirlees JS12VT four-stroke engine. The Sri Lanka railway had a fleet of 25 of these Class M1 locomotives which began introduction in 1953 and were removed from service from 1983.[2]

Locomotive number 560 is the subject of a restoration attempt.[4]


In the 1950s Sri Lankan railway was seeking replacements for old rolling stock, routine replacement of which had been delayed by World War II. Specifications were for 25 locomotives with 750 hp (559 kW) power at the wheel, available from 12 mph (19 km/h) upwards, and up to an altitude of 6,200 ft (1,900 m).[5] The train was expected to be used for suburban trains centered on Colombo, as well as mail trains in the north of the country, and trains in hill areas: approximately requirements were for a vehicle capable of pulling 550 long tons (560 t; 620 short tons) at 18 mph (29 km/h) on a gradient of 1 in 44 (2.27%) on track with 5-chain (330 ft; 101 m) reverse curves; preferably within a 80 long tons (81 t; 90 short tons) locomotive weight on 6 axles (A1A-A1A). Several firms tendered for the contact; American suppliers were unable to enter a competitive bid due to the devaluation of both the rupee and British pound.[6]

Brush offered a locomotive with 1,000 hp (746 kW) power, and a generator output of 625 hp (466 kW), capable of multiple working,[7] and was awarded the contract.[5] Five locomotives were supplied (deliveries beginning Jan. 1953) for operational testing – Brush had not been able to fully stress test the units in England due to an absence of a full scale 5 ft 6 in (1,676 mm) test track.

During testing engine overheating was found to be a serious problem on the steeply graded and curving mainline. Other issues requiring attention included fuel pump problems including air-locks, and bogie frame cracking. The electrical circuit for torque control was also modified.[8]

The remaining twenty locomotives, with modifications required to resolve the issues found during testing were delivered from May 1954, at a rate of approximately 1 per month.[9]

See also


  1. Hughes 1996, p. 92.
  2. "Diesel Locomotives of Sri Lanka : Locomotive classification". M1. Archived from the original on 29 October 2013.
  3. Ravi Fernando (30 August 2001). "The unforgettable 'M1' locomotive". Daily News (Sri Lanka). Retrieved 7 November 2013. Also reprinted at
  4. "Brush Bagnall Sri Lanka - Restoration Website". Class M1 Locomotive Restoration web site. Retrieved 11 June 2012.
  5. Rapala 1956, p. 325.
  6. Rapala 1956, pp. 325-7.
  7. Rapala 1956, pp. 328-9.
  8. Rapala 1956, pp. 331-2.
  9. Rapala 1956, p. 339.


  • Hughes, Hugh (1996). Indian Locomotives: Part 4 – 1941–1990. Harrow, Middlesex: The Continental Railway Circle. ISBN 978-0-9521655-1-4.
  • Rapala, B. D. (1956), "Diesel electric traction in Ceylon", Journal of the Institution of Locomotive Engineers, 46 (252): 314–326, doi:10.1243/JILE_PROC_1956_046_044_02
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