South Australian Railways W class

South Australian Railways W/Wx class
NF5 (formerly W53) preserved at Pine Creek, Northern Territory
Type and origin Power type Steam Builder Beyer, Peacock & Co Build date 1877-1882 Total produced 35
Specifications Configuration: ​  • Whyte 2-6-0 Gauge 1,067 mm (3 ft 6 in) Driver dia. 3 ft 3 in (0.991 m) Adhesive weight 33,040 lb (14,987 kg) Loco weight 42,000 lb (19,051 kg) Fuel type Coal Firebox:  • Firegrate area 45 sq ft (4.2 m2) Boiler pressure W: 130 psi (896 kPa) Wx: 145 psi (1,000 kPa) Heating surface 544 sq ft (50.5 m2) Cylinders 2 Cylinder size 12 in × 20 in (305 mm × 508 mm)
Performance figures Tractive effort 8,159 lbf (36.29 kN) Factor of adh. 4.05
Career Operators South Australian Railways 1877–1929 Commonwealth Railways 1911–1950 Numbers 32, 33 Disposition 2 preserved, 1 destroyed in air raid, 32 scrapped

The South Australian Railways W/Wx class was a class of 2-6-0 steam locomotives operated by the South Australian Railways and later the Commonwealth Railways.

The W class were ordered as light goods locomotives for use on the expanding South Australian Railways (SAR) 3 ft 6 in (1,067 mm) gauge networks, limited in size and weight by the requirement they must be able to run on 40 lb/yd rails as were in use at the time. The locomotives were built by Beyer, Peacock & Co of Manchester as a variation on the narrow gauge Mogul design widely used in Australia at the time.

Early W class units were used during construction of the Central Australia Railway between Port Augusta and Quorn in 1878 prior to entering revenue service with SAR. During their operational career, the locomotives were used within South Australia on the isolated Eyre Peninsular Railway, in the south east on now closed lines in the Kingston, Naracoorte and Mount Gambier areas as well as the line north from Port Augusta. Many were sold or leased to contractors and they were also used by the Railways Construction Branch. Several of the locomotives were sold to C&E Millar and used for construction of the Palmerston and Pine Creek Railway in the Northern Territory and would continue to work the isolated line for the remainder of their operational lives.