South African Class 25 4-8-4
The class 25 of the South African Railways (SAR ) is a steam locomotive with Kondenseinrichtung, the most powerful and longest- used locomotive of this type. The series was ( so "non condensing " without Kondenseinrichtung ) supplied as Class 25 NC.
Development and testing
On long routes through the Karoo desert, the water consumption of the locomotives was a serious problem. Some of the water with tank car trains had to be brought to the supply locations so that more water features were in particularly dry years as freight trains go.
Even before World War II, the SAR was aware of the constructed by Richard Roosen and built by the Henschel factory Kondenslokomotiven for Argentina, Iraq and the Soviet Union. This technique, which could reduce water consumption by up to 90 %, would be able to solve the problem.
Only after the war, the idea could be pursued and Henschel delivered in 1950 the first attempt tender. It was a conversion of a still existing Kriegslok - Kondenstenders 3'2'T16. The tender had been extended to adapt it to the increased power and to the special conditions in South Africa (higher temperatures, lower air pressure due to the sometimes very high-altitude routes). Of course, he also received other bogies for the common in South Africa Cape gauge.
The condensation tender was provided for the built of the SAR itself single piece of class 20, a 1'E1' locomotive, but could also be coupled with the classes 19D and 24. The tests were successful; the locomotive had under favorable conditions, a range of more than 1000 km and there were no major technical problems.
The SAR then ordered 90 locomotives of Class 25 and a further 50 Class 25 NC, which were supplied by the Henschel factory as well as the North British Locomotive Company in the years 1953 and 1954. They were given the operating numbers 3451-3540 (Class 25) and 3401-3450 ( Class 25 NC). Note: Unlike the German railways operating numbers of the SAR contained a defined reference to the class of locomotive: the respective series or classes were permanently assigned to certain allocated only once numbers.
Technology
Although the locomotives of the class were built for the 25 predominant in southern Africa Cape gauge, they are heavier and more powerful than almost all standard gauge steam locomotives outside North America. The main lines of the SAR were then designed for an axle load of 20 t; corresponding amount of power ( 2,500 kW) and traction were able to develop the eight-axle locomotives with the wheel arrangement 2'D2 ' (Northern).
The locomotives were on the latest technology and had cast steel frame, roller bearings on all axles and rods as well as Stoker and a steam-driven reversal. The driving wheel diameter was five feet ( 1,524 mm), so that the locomotives could be used both for travel and for freight trains. Both the condensation and the conventional tender had two three-axle bogies, where the condensation tender but were significantly longer.
The fan and fan turbines were operated with the exhaust steam, which while still a power of about 125 kW was taken. Also, the air escaping from the safety valves steam condensation was supplied. The tender for leading from the cylinders exhaust pipe was - as for the series 52 - on the left side of the locomotive.
The smoke chamber were self-cleaning ("self -cleaning front end" ), wherein a gas guide made sure that the Delete could not settle, but along with the exhaust gases was blown out of the chimney.
Rebuilding
After the operation the condensing locomotives was no longer necessary by the use of diesel and electric locomotives, they were converted because of their higher operating costs in 1978 in the workshops of the Salt River / Cape Town in the class NC 25. Only two specimens retained their condensation tender.
The rebuilt locomotives were out of their operation number can also be seen in the unusually long, rounded up tenders, which were created by the reconstruction of the Kondenstendern whose cast steel frame could not be shortened.
End of the operational use
The locomotives of Class 25 NC were among the last steam locomotives used on main lines in South Africa and were until the early 90s into scheduled service.
A locomotive, No. 3540, was rebuilt in 1981 in the class of 26. The goal was a significant reduction of water and carbon consumption while increasing performance. It remained, however, with this one modification, as well as in South Africa, the end of the steam locomotive operation became apparent. This locomotive, named after its red color " Red Devil ", is considered as the most modern steam locomotive in the world.
Some of the locomotives are operable to part, nor received today, which has taken place the last ride of the two non- converted Kondenslokomotiven (No. 3511 ) in 1992. The locomotive is but preserved in museums to this day. Locomotive No. 3405, was taken in 1991 shortly after they are decommissioned, returned to England and is in Buckinghamshire Railway Centre near Aylesbury (see image ).