South Australian Railways S class
S class locomotive no 17 at Tailem Bend in 1952
Type and origin Power type Steam Builder James Martin & Co Serial number 71–76, 93–98, 176–181 Build date 1894 (12), 1903–1904 (6) Total produced 18 Rebuilder Islington Railway Workshops Rebuild date 1915 (No. 13) Number rebuilt 1
Specifications Configuration: ​  • Whyte 4-4-0 (2′B 2′2′) Gauge 1,600 mm (5 ft 3 in) Leading dia. 2 ft 11 in (889 mm) Driver dia. 6 ft 6 in (1,981 mm) Length 57 ft 5⁄8 in (17,389 mm) Height 13 ft 3 in (4,038.6 mm) Axle load 12 long tons 15 hundredweight (14.3 short tons; 13.0 tonnes) Loco weight 87,360 lb (39,625.829 kg) Tender weight 96,746 lb (43,883.247 kg) Total weight 184,106 lb (83,509.077 kg) Fuel type Coal Fuel capacity 7 long tons 16 hundredweight (8.7 short tons; 7.9 tonnes), 4 long tons 18 hundredweight 3 quarters (5.53 short tons; 5.02 tonnes) (6 wheel tender) Water cap. 4,120 imperial gallons (18,700 litres; 4,950 US gallons), 2,040 imperial gallons (9,300 litres; 2,450 US gallons) (6 wheel tender) Firebox: ​  • Grate area 17.37 square feet (1.614 m2) Boiler pressure 150 psi (1,034 kPa) Heating surface: ​  • Firebox 100.24 square feet (9.313 m2)  • Tubes 1,038 square feet (96.4 m2) Cylinders 2 Cylinder size 18 in × 24 in (457 mm × 610 mm) Valve gear Stephenson Valve type Piston
Performance figures Tractive effort 12,711 lbf (56.54 kN) Factor of adh. 4.49
Career Operators South Australian Railways Class S Number in class 18 Numbers 11, 13, 14, 17, 26, 50, 127-137, 154 First run 26.2.1894 Withdrawn 1942-1960 Scrapped 1956-1961 Disposition all scrapped

The South Australian Railways S class was a class of 4-4-0 steam locomotives operated by the South Australian Railways.

The S Class locomotives were designed as an express locomotive for the route between Murray Bridge and the border with Victoria. The first 12 were delivered by James Martin & Co in 1894, followed by a further six in 1903/04. They type was notably used to haul the Melbourne Express. The S class had 6'6" driving wheels, the largest of any Australian locomotive, to give it high speeds on low grades.^[1][2][3]

The engines were pushed out of main line service in the 1920s by 600 class locomotives and Brill railcars. They continued to serve on secondary services into the 1950s. Some locomotives even served in shunting duties despite being unsuitable due to their large wheel diameter. The last examples were retired in 1961.^[1][3]

S136 was set aside for preservation at Islington Railway Workshops while moves were made to preserve it. These fell through and it was scrapped.^[3]

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