SAR class GA
| SAR class GA | |
|---|---|
_Ex_1649.jpg) The locomotive around 1921
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| Numbering: | 1649, later 2140 |
| Number: | 1 |
| Manufacturer: | Beyer-Peacock |
| Year of construction (s): | 1920 |
| Retirement: | 1938 |
| Type : | (1'C) (C1 ') h4 (Garratt) |
| Gauge : | 1067 mm ( cape track ) |
| Length over coupling: | 19,960 mm |
| Service mass: | 136 t |
| Friction mass: | 106 t |
| Wheel set mass : | 17.8 t |
| Driving wheel diameter: | 1219 mm |
| Impeller diameter: | k. A. |
| Cylinder diameter: | 457 mm |
| Piston stroke: | 660 mm |
| Boiler overpressure: | 124.1 N / cm² |
| Grate area: | 4.81 m² |
| Radiant heating surface: | 19.63 m² |
| Tubular heating surface: | 217.7 m² |
| Superheater area : | 48.9 m² |
| Train brake: | Suction air brake |
The SAR class GA refers to the first Garratt steam locomotive of the then South African Railways (SAR). The only example of this class built was by far the largest Garratt locomotive built to date. It was intended for mainline service on the South African rail network with Cape gauge and had an axle load of 17.8 tons.
Together with three locomotives of the NGG 11 class and one of the GB class , the locomotive had already been ordered in 1914; However, it was not delivered until 1920 because of the First World War.
The locomotive with the wheel arrangement (1'C) (C1 ') was compared extensively with the (1'C) C1'Mallet locomotives of class MH , which could generate roughly the same tractive effort. This resulted in significantly lower water and coal consumption for the GA at a higher average speed and a higher train weight. The Mallett locomotives were only equivalent to the Garratt locomotive on inclines. In addition, the empty weight of the GA boiler was almost 11 tons below that of the MH boiler with roughly the same boiler output, which was due to the more favorable ratio between radiant and tubular heating surface in the comparatively short and larger diameter Garratt boiler.
The results of the comparison brought the breakthrough for the Garratt design in South Africa. However, since there was a high level of flange wear on the inner coupling wheels , which in turn was attributed to the lack of internal running axles , no further copies of the same type were built.
The locomotive was mainly used in Natal and last pulled passenger trains between Ladysmith and Harrismith , where a pass with gradients of up to 33.3 ‰ had to be crossed. As a single item, the locomotive was retired and scrapped in 1938; the boiler was used as a replacement part for the GE class .
literature
- AE Durrant: Garratt locomotives of the world. Birkhäuser, Basel 1984, ISBN 3-7643-1481-8
