South African Class 15 4-8-2

In 1914 the South African Railways placed ten Class 15 steam locomotives with a 4-8-2 Mountain wheel arrangement in service.^[4]

Manufacturer

The Class 15 was introduced by D.A. Hendrie, Chief Mechanical Engineer (CME) of the South African Railways (SAR) from 1910 to 1922, as a large mixed traffic locomotive for use in the Orange Free State where grades and curvature were less severe than on the coastal sections. Designs were prepared in 1913 for this locomotive, similar in general layout to the Class 12 and Class 14, but with larger 57 inches (1,450 millimetres) coupled wheels. Ten locomotives were built by the North British Locomotive Company (NBL) and delivered in 1914, numbered 1561 to 1570.^[2]

They had plate frames, Walschaerts valve gear, Belpaire fireboxes without combustion chambers and were superheated. In order to reduce the weight on the trailing wheels, steel fireboxes were used. This last feature became standard on large locomotives, but necessitated the introduction of water treatment plants in some parts of the country to prevent corrosion.^[2][4][5]

The locomotive’s one flaw was excessively long fire tubes. On later models like the Class 15A Hendrie improved the boiler by adding a combustion chamber and shortening the distance between tube plates from 21 feet 9 inches (6.629 metres) to 19 feet (5.791 metres) in the process.^[2]

Watson Standard boilers

During the 1930s many serving locomotives were reboilered with a standard boiler type designed by A.G. Watson, CME of the SAR from 1929 to 1936, as part of his standardisation policy. Such Watson Standard reboilered locomotives were reclassified by adding an "R" suffix to their classification.^[3][4]

When all ten Class 15 locomotives were reboilered with Watson Standard no. 2A boilers, they were reclassified to Class 15AR since the only differences between the as delivered Class 15 and the Class 15A lay in the length of their boilers and whether they were built with or without combustion chambers. In the process they were also equipped with Watson cabs, with their distinctive slanted fronts, compared to the conventional vertical fronts of their original cabs. Some were equipped with steel and others with copper fireboxes.^[4]

An obvious visual difference between an original and a Watson Standard reboilered locomotive is usually a rectangular regulator cover just to the rear of the chimney on the reboilered locomotive. In the case of the Class 15 and Class 15AR two even more obvious visual differences are the Watson cab and the absence of the Belpaire firebox hump between the cab and boiler on the reboilered locomotives.^[3]

Service

The Class 15 was placed in service in the Orange Free State, stationed at Bloemfontein. After reboilering and reclassification they became part of the much larger Class 15AR fleet and saw service widely throughout the country, getting used in every kind of role from dock shunting to mainline passenger work.^[2][4]

The Cape Northern examples were scattered between De Aar, Kimberley and Klerksdorp. The Cape Midland was a major user of the class, with locomotives shedded at Sydenham in Port Elizabeth, Klipplaat, Graaff Reinet and Noupoort. The Class 15AR also handled the suburban services between Port Elizabeth and Uitenhage until they were replaced by diesel power.^[5]

Near the end of their service lives in the early 1980s they were all relegated to shunting work at centres all around the country, except for some that were hired out to Swaziland and that were still employed in main line service on the Swaziland Railway, until they were also eventually replaced by diesel traction and retired.^[5]

Gallery

The main picture shows number 1566, reboilered and reclassified to Class 15AR, at Port Elizabeth on 3 April 1978.

See also

• South African Class 15A 4-8-2
• South African Class 15B 4-8-2
• South African Class 15C 4-8-2
• South African Class 15CA 4-8-2
• South African Class 15E 4-8-2
• South African Class 15F 4-8-2
• Tender locomotive numbering and classification
• Watson Standard boilers
• The 4-8-2 "Mountain"
• List of South African locomotive classes

References

1. ^ ^{a b} North British Locomotive Company works list, compiled by Austrian locomotive historian Bernhard Schmeiser
2. ^ ^{a b c d e} Holland, D.F. (1972). Steam Locomotives of the South African Railways, Volume 2: 1910-1955 (1st ed.). Newton Abbott, Devon: David & Charles. p. 26. ISBN 0715354272. 
3. ^ ^{a b c} South African Railways and Harbours Locomotive Diagram Book, 2’0” & 3’6” Gauge Steam Locomotives, 15 August 1941, as amended
4. ^ ^{a b c d e} Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 10-11, 59-60. ISBN 0869772112. 
5. ^ ^{a b c} Durrant, A E (1989). Twilight of South African Steam (1st ed.). Newton Abbott, London: David & Charles. pp. 83-84. ISBN 0715386387.