page_title: South African Class 25 4-8-4
section_title: Rebuilding
hierarchical_section_title: South African Class 25 4-8-4 / Rebuilding
caption_attribution_description: English: Type EW2 tender rebuild plate of SAR Class 25NC no. 3454
context_page_description: The South African Railways Class 25 4-8-4 of 1953 was a condensing steam locomotive.
  Between 1953 and 1955, the South African Railways placed ninety Class 25 condensing steam locomotives with a 4-8-4 Northern type wheel arrangement in service. The Class 25NC which was placed in service at the same time was a non-condensing version of the Class 25 condenser.
context_section_description: The Class 25 was a complex locomotive which required high maintenance, especially on the turbine blower fans in the smokebox, the blades of which needed to be replaced frequently due to damage by solid particles in the exhaust. The equally complex condensing tender also needed frequent maintenance. Between 1973 and 1980, after serving for twenty years, and partially accelerated by the introduction of electric and diesel-electric traction over routes which were previously served exclusively by the Class 25, all but three of the condensing locomotives, numbers 3451, 3511 and 3540, were converted to free exhausting and non-condensing locomotives as they went through the workshops for major overhauls. The converted locomotives were reclassified to Class 25NC.
  It has been suggested that, had the Class 25 been modified to produce less black smoke or char as a result of incomplete combustion, in accordance with the Gas Producer Combustion System (GPCS) principles, which were applied by mechanical engineer David Wardale when he rebuilt a Class 25NC locomotive to the Class 26 Red Devil, the problem of char damage to the fan blades could have been largely eliminated. The GPCS program, however, only began near the end of the conversion of the Class 25s.
  The first conversion was done at De Aar on no. 3452, and consisted of the turbine and exhaust pipe being removed from the smokebox and replaced with a blastpipe and chimney. The tender was stripped of its condensing equipment, but retained its original fresh water and condensate tanks and feed pumps, with the radiator framing and roof panelled over. The locomotive's general appearance therefore changed little, but while the conversion of no. 3452 was aesthetically superior when compared with subsequent conversions, it did not carry enough water.
  The rest of the fleet was rebuilt at the Salt River shops in Cape Town. 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 them with a massive round-topped water tank.
  The shape and appearance of the tender conversion was dictated by strength considerations. Shortening the tender frame was considered, but it was eventually retained as it was. To replicate the Class 25NC tender tank and bunker on the longer Type CZ tender frame would have exceeded the permissible axle loading by a considerable amount. The long cast-steel frame of the tender was very flexible, but the radiator framing and roof contributed a great deal to the vertical stiffness. The final form of the rebuilt tender's tank supplied enough strength, with its semi-circular top welded to the original fresh water tank via the fan supports and the long triangular gussets set into the bunker sides which extended past the midpoint of the frame. Locomotives with rebuilt tenders were soon nicknamed Worshond, Afrikaans for dachshund and literally translated as sausage dog. The worshond tenders were reclassified as Type EW2.
  When the Class 25 condensers were converted to Class 25NC non-condensers, their number plates were copied and recast with the additional "NC" for "non-condensing" squeezed in next to the existing "25", which resulted in a lopsided class indication on their plates. Locomotives with all four characters neatly in line and centred were therefore usually identifiable as original Class 25NCs. After they were relieved of their condensing gear, these locomotives served for another eleven years, before being withdrawn from service by the SAR when steam was completely replaced by electric and diesel-electric traction.
caption: Salt River Shops rebuild plate
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