South African Class 21 2-10-4

The locomotive class 21 of the South African Railways (SAR ) was a steam locomotive with the wheel arrangement 1'E2 ' (Texas ). The single piece with the train number 2551 was delivered in 1937 by North British.

The locomotive was developed with the intention to build a powerful as possible, but not articulated locomotive with 15 t axle load. To be able to go through tighter turns, the wheels of the driving axle and another dome axis without wheel flanges were performed. The boiler was the standard boiler 3B, which was also used in the class 15E and F, and 23. A Caprotti valve control provided the locomotive was built but then with Walschaerts control - Originally - as many in this period built for the SAR locomotives.

Also, the six-axle tender - the first of the SAR - was an experimental design: He had the wheel arrangement 1'4 1 ', four mounted firmly in the frame axes and two designed as a bissel end axles. The experiment was not repeated; all other six-axle tender of the SAR received three-axle bogies.

Quintuple -coupled locomotives were in South Africa also not prevail. Only one type has been built in series, which in 1899 introduced " Reid ten- wheeler" of the Natal Government Railways. The only four five -coupled Tender locomotives were distributed among three experimental designs: the 1927 -built Class 18 ( 1'E1 ') with three-cylinder engine, the 1934 -built Class 20 ( also 1'E1 ") and finally the class 21

The No. 2551 was mainly in the region around Pretoria in use and was scrapped in 1952 after 15 years of operation.

Class 22

The SAR had another 1'E2' locomotive in planning, which was designed, in contrast to class 21 for 22 t axle load. Provided a driving wheel diameter of 5 feet (1524 mm), a grate area of 7.43 m² and a total weight ( without tender ) was of about 142 tons. The locomotive would therefore have been larger and heavier than the built after the war Class 25 ( wheel arrangement 2'D2 ' with the same driving wheel diameter ).

Although the draft was given the class designation 22 was not built because the high axle load would have limited the use of the locomotive on a few main routes. The 22 is thereby the only gap in the class designations 1 to 26 for the Tender Steam Locomotives of the SAR.