The Tasmanian Government Railways M class is a class of 4-6-2 steam locomotives operated by the Tasmanian Government Railways.

Tasmanian Government Railways M class
M5 at the Tasmanian Transport Museum
Type and origin Power type Steam Builder Robert Stephenson and Hawthorns Serial number 7421-7430 Build date 1951 Total produced 10 Rebuilder Tasmanian Government Railways, Inveresk Rebuild date 1957 Number rebuilt 4 (MA class)
Specifications Configuration: ​  • Whyte 4-6-2 Gauge 1,067 mm (3 ft 6 in) Leading dia. 2 ft 2.5 in (0.673 m) Driver dia. M: 4 ft 7 in (1,397 mm) MA: M: 4 ft 0 in (1,219 mm) Trailing dia. 2 ft 4+1⁄2 in (0.724 m) Length 59 ft 2+3⁄4 in (18.053 m) Axle load Loco: 10.20 long tons (10.4 t) Tender: 10.60 long tons (10.8 t) Adhesive weight 37.25 long tons (37.8 t) Loco weight 54.20 long tons (55.1 t) Tender weight 42.40 long tons (43.1 t) Fuel type Coal Fuel capacity 6 long tons (6.1 t) Water cap. 4,000 imp gal (18,184.4 L) Firebox:  • Firegrate area 23.1 sq ft (2.146 m2) Boiler pressure 180 lbf/in2 (1.24 MPa) Heating surface:  • Tubes 601 sq ft (55.8 m2)  • Flues 371 sq ft (34.5 m2)  • Firebox 371 sq ft (34.5 m2) Superheater: ​  • Type 18 element  • Heating area 371 sq ft (34.5 m2) Cylinders 2 outside Cylinder size 16 in × 24 in (406 mm × 610 mm)
Performance figures Tractive effort M: 17,090 lbf (76.02 kN) MA: 19,600 lbf (87.19 kN) Factor of adh. 3.44
Career Operators Tasmanian Government Railways Numbers M1-M10 Disposition All preserved

History

On 12 March 1952, the Tasmanian Government Railways (TGR) took delivery of ten M class branch line locomotives from Robert Stephenson and Hawthorns, Newcastle-upon-Tyne. The locomotives were similar to the Indian Railways YB class.[1][2]

They were allocated to operate on the North-Eastern and Western lines and at Hobart. However with the TGR having already commenced dieselisation with the X class, some of the lines intended for M class operation had already been converted. Hence in 1957, four were fitted with smaller driving wheels recovered from withdrawn Australian Standard Garratts enabling them to operate heavier trains over the steeply graded North-Eastern line.[1][3][4]

As they fell due for overhaul, they were withdrawn from 1960, with the last removed from traffic in 1975.[1]

Preservation

All members of the class have been preserved to an extent, with four locomotives seeing further use on heritage trains.

Namesake

The M class designation was previously used by the M class, the last of which was withdrawn in 1931.

References