The M class locomotive was an articulated Garratt locomotive with the wheel arrangement 4-4-2+2-4-4 that ran on the Tasmanian Government Railways system [1]. It was designed for relatively high speed on the narrow 1,067 mm (3 ft 6 in) gauge lines, for passenger use. They were the only eight-cylinder Garratt engines ever produced.[2] Despite their speed and haulage capabilities they were difficult to maintain, and after three fatal accidents in the late 1920s they were withdrawn from service.