Sri Lanka Railway - Class M1 locomotives

Loco Builder                           : Brush Bagnall in England

Engine Builder & Model        : Mirrlees - J V S 12

Power                                      : 1000 h.p.

Max Speed                              : 88 Km/h

Dead Weight                           : 88 ton

Length                                    : 50” 9’

Wheel Arrangement               : A1A-A1A

Introduced Year                     : 1953-1956

Withdrawn Year                    : 1980-1984

No Range                                : 539-563

No of Locos                            : 25

Introduction

In the 1950s Sri Lankan railway was seeking replacements for old rolling stock, routine replacement of which had been delayed by the 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) at 18 mph (29 km/h) on a gradient of 1 in 44 on track with 5-chain (330 ft; 100 m) reverse curves; preferably within a 80 long tons (81 t) 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 the 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 scale5 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 fortorque 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]