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.

The locomotives weighed 88 LT had a 1000 hp 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.

Locomotive number 560 is the subject of a restoration attempt.

Introduction
In the 1950s Sri Lankan Railways 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 power at the wheel, available from 12 mph upwards, and up to an altitude of 6200 ft. 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 LT at 18 mph on a gradient of 1 in 44 (2.27%) on track with 5 chain reverse curves; preferably within an 80 LT 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.

Brush offered a locomotive with 1000 hp power, and a generator output of 625 hp, capable of multiple working, and was awarded the contract. 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 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.

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.