page_title: 4-8-4
section_title: South Africa
hierarchical_section_title: 4-8-4 / Usage / South Africa
caption_attribution_description: English: SAR Class 25 3511 (4-8-4) NBL 27371Location: Hartswater
context_page_description: Under the Whyte notation for the classification of steam locomotives, 4-8-4 represents the wheel arrangement of four leading wheels on two axles, eight powered and coupled driving wheels on four axles and four trailing wheels on two axles. The type was first used by the Northern Pacific Railway, and initially named the Northern Pacific, but railfans and railroad employees have shortened the name when referring to the type, and now is most commonly known as a Northern.
context_section_description: Between 1953 and 1955, the South African Railways (SAR) placed fifty Class 25NC 4-8-4 Northern locomotives in service. Designed under the direction of Chief Mechanical Engineer L.C. Grubb, eleven of these locomotives were built by North British Locomotive Company (NBL) and 39 by Henschel & Son. They were tended by Type EW1 tenders which rode on six-wheeled bogies. Two versions of the same locomotive were built, the Class 25NC being the non-condensing version, hence the "NC" suffix to the class number.
  Ninety Class 25 condensing locomotives were introduced simultaneously, acquired as a means to deal with the shortage of adequate supplies of suitable locomotive water in the arid Karoo. The design work on the engine’s condensing apparatus and the enormous condensing tender was carried out by Henschel, who built one locomotive complete with tender as well as sixty of the condensing tenders, to which they held the patent. The other 89 condensing locomotives and thirty tenders were built by NBL.
  The Type CZ condensing tenders were slightly longer than their engines. One-third of the total length of the tender was taken up by the water tank and coal bunker, while the rest was taken up by eight large radiators on each side, cooled by five steam-driven roof-mounted fans. Roller bearings were used throughout on all these locomotives, including the coupling and connecting rods, the crosshead gudgeon pins as well as the three-axle bogies of both the standard and condensing tenders. The leading bogies and coupled wheels had Cannon-type axle boxes. The cylinders and frames were cast in one piece, while the steel cylinders and steam chests were fitted with cast iron liners. The tender frames of both locomotive types were also one-piece steel water-bottom castings. Since they were entirely mounted on roller bearings, very little effort was required to move these big locomotives.
  On the condensing locomotives, spent steam was recycled and condensed back to water for repeated use. Since the steam was not expelled up the chimney, the smokebox contained a steam turbine-driven fan beneath the chimney to keep the draught going. Visual evidence of this altered and slightly longer smokebox is the locomotive’s banjo-face smokebox front. The condensing system proved extremely efficient and reduced water consumption by as much as 90% by using the same water up to eight times over, which gave the Class 25 a range of 800 kilometres (500 miles) between water refills. In addition, the hot condensate feedwater resulted in significantly reduced coal consumption.
  However, the Class 25 was a complex locomotive that required high maintenance, especially on the turbine blower fans in the smokebox, whose blades needed to be replaced frequently due to damage by solid particles in the exhaust. The equally complex condensing tender also required frequent maintenance. Between 1973 and 1980, partly motivated by the spread of electric and diesel-electric traction, all but three of the locomotives were converted to free-exhausting and non-condensing locomotives and reclassified to Class 25NC. In the process their condensing tenders were also rebuilt to ordinary coal-and-water tenders by removing the condensing radiators and roof fans and replacing it with a massive round-topped water tank. Since the tenders were built on single cast-steel main frames, it was impractical to attempt to shorten them. Locomotives with these rebuilt Type EW2 tenders were soon nicknamed Worshond (Sausage dog or Dachshund).
  The Class 26, popularly known as the Red Devil, was rebuilt from Henschel-built Class 25NC no. 3450 by mechanical engineer David Wardale. The rebuilding took place at the Salt River shops of the SAR in Cape Town and was based on the principles developed by Argentinian mechanical engineer Livio Dante Porta. The primary objectives of the modifications were to improve the combustion and steaming rate to reduce the emission of wasteful black smoke and to overcome the problem of clinkering. This was achieved by the use of a Gas Producer Combustion System (GPCS), which relie
caption: SAR Class 25 no. 3511
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