South African Class S 0-8-0

South African Class S 0-8-0
No. 355 at Millsite, 8 April 1966
Type and origin Power type Steam Designer South African Railways (Col F.R. Collins DSO) Builder Henschel and Son Serial number 21071-21084 Model Class S Build date 1928 Total produced 14
Specifications Configuration: ​  • Whyte 0-8-0 (Eight-coupled)  • UIC Dh2 Driver 3rd coupled axle Gauge 3 ft 6 in (1,067 mm) Cape gauge Coupled dia. 48 in (1,219 mm) Tender wheels 34 in (864 mm) Wheelbase 48 ft 2 1⁄16 in (14,683 mm)  • Engine 14 ft 9 in (4,496 mm)  • Coupled 14 ft 9 in (4,496 mm)  • Tender 20 ft 5 in (6,223 mm)  • Tender bogie 6 ft 2 in (1,880 mm) Length: ​  • Over couplers 64 ft 10 5⁄16 in (19,769 mm) Height 13 ft (3,962 mm) Frame type Bar Axle load 18 LT (18,290 kg)  • Coupled 18 LT (18,290 kg)  • Tender bogie Bogie 1: 29 LT 4 cwt (29,670 kg) Bogie 2: 31 LT 19 cwt (32,460 kg)  • Tender axle 15 LT 19 cwt 2 qtr (16,230 kg) Adhesive weight 72 LT (73,160 kg) Loco weight 72 LT (73,160 kg) Tender weight 61 LT 3 cwt (62,130 kg) Total weight 133 LT 3 cwt (135,300 kg) Tender type GT (2-axle bogies) Fuel type Coal Fuel capacity 8 LT (8.1 t) Water cap 6,000 imp gal (27,300 l) Firebox type Round-top  • Firegrate area 41 sq ft (3.8 m2) Boiler: ​  • Pitch 8 ft 6 in (2,591 mm)  • Diameter 5 ft 6 1⁄8 in (1,680 mm)  • Tube plates 14 ft (4,267 mm)  • Small tubes 135: 2 in (51 mm)  • Large tubes 28: tubes 5 1⁄2 in (140 mm) Boiler pressure 170 psi (1,172 kPa) Safety valve Pop Heating surface 1,699 sq ft (157.8 m2)  • Tubes 1,554 sq ft (144.4 m2)  • Arch tubes 20 sq ft (1.9 m2)  • Firebox 125 sq ft (11.6 m2) Superheater: ​  • Heating area 450 sq ft (42 m2) Cylinders Two Cylinder size 23 1⁄4 in (591 mm) bore 25 in (635 mm) stroke Valve gear Walschaerts Valve type Piston Couplers AAR knuckle
Performance figures Tractive effort 35,890 lbf (159.6 kN) @ 75%
Career Operators South African Railways Class Class S Number in class 14 Numbers 360-373 Delivered 1929 First run 1929 Withdrawn 1976
The 3rd coupled axle had flangeless wheels

The South African Railways Class S 0-8-0 of 1929 was a steam locomotive.

In 1929, the South African Railways placed fourteen purpose-built Class S steam shunting locomotives with a 0-8-0 wheel arrangement in service.

Throughout the history of railways in South Africa, shunting was traditionally performed by downgraded mainline locomotives. Considering the enormous amount of shunting performed, the number of dedicated shunting locomotives on the South African Railways (SAR) roster in the steam era was remarkably low, amounting to only 151 locomotives on a railway whose steam stock at one stage reached a maximum of nearly 2,800 locomotives.

When it did eventually introduce purpose-built shunting locomotives, the SAR preferred to adhere to the American practice of using tender locomotives for shunting rather than the European practice of using tank engines.

In spite of the conversion of Class A tank locomotives to Class 17 tank-and-tender shunting locomotives, increasing rail traffic throughout the country and particularly on the Witwatersrand in the 1920s still made it necessary to use heavy mainline locomotives for shunting work. Specifications for the Class S 0-8-0 tender type steam shunting locomotive were therefore prepared by Colonel F.R. Collins DSO, Chief Mechanical Engineer of the SAR.

In 1928, fourteen locomotives were built to the SAR specifications by Henschel and Son in Germany. They were delivered in 1929 and numbered in the range from 360 to 373. Since they were designed to operate at low speeds in tightly curved shunting yards, there was no need for the leading or trailing wheels which are necessary on mainline locomotives to improve high speed stability. In addition, it was desirable to have as large a proportion of the engine weight as possible carried on the coupled wheels to obtain the maximum adhesion possible.

The Class S locomotives were superheated, were built on bar frames and used Walschaerts valve gear with piston valves. They were delivered with Type GT tenders with a fuel capacity of 8 long tons (8.1 tonnes), a water capacity of 6,000 imperial gallons (27,300 litres) and a maximum axle load of 15 long tons 19 hundredweight 2 quarters (16,230 kilograms). To improve the crew's rearward vision, the top sides of the tender's coal bunker were set inwards and the water tank top was rounded.