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South African class 12A
The 4-8-2 locomotive of the class 12A was the last design by D.A. Hendrie for the South African Railways. It was based on the class 12 that had been introduced before World War I. The biggest change was that the area ...
General
| Property | South African class 12A 12A |
|---|---|
| Built | 1919-1929, 1947-1953 |
| Manufacturers | North British, Henschel |
| Wheel arrangement | 4-8-2 (Mountain) |
| Gauge | 1,067 mm (Cape gauge) |
Dimensions and weights
| Property | South African class 12A 12A |
|---|---|
| Length | 20.41 m |
| Wheelbase | 9.78 m |
| Rigid wheelbase | 4.12 m |
| Total wheelbase | 17.86 m |
| Service weight | 100.6 t |
| Adhesive weight | 70.3 t |
| Axle load | 17.6 t |
| Total weight | 152.5 t |
| Water capacity | 19,321 l |
| Fuel capacity | 10.2 t (coal) |
Boiler
| Property | South African class 12A 12A |
|---|---|
| Grate area | 3.763 m² |
| Firebox surface | 19.417 m² |
| Tube heating surface | 213.77 m² |
| Evaporative heating surface | 233.187 m² |
| Superheater surface | 43.293 m² |
| Total heating surface | 276.5 m² |
Power plant
| Property | South African class 12A 12A |
|---|---|
| Driver diameter | 1,295 mm |
| Boiler pressure | 13.1 bar |
| Expansion type | simple expansion |
| Cylinders | two, 610 x 660 mm |
Power
| Property | South African class 12A 12A |
|---|---|
| Power source | steam |
| Estimated power | 969 kW (1,317 PS) |
| Starting effort | 211.0 kN |
Calculated values
| Property | South African class 12A 12A |
|---|---|
| Factor of adhesion | 1 : 3.27 |
| Optimal speed | 27 km/h |
| Power-to-weight ratio | 9.6 kW/t |
| Heating Surface Equivalent | 416.9 m² |
| Cylinder volume/HSE | 1 : 924.76 |
| Adhesive weight/Total | 1 : 1.43 |
| Tractive force/Heating surface | 1 : 15.94 |
| Grate area/Heating surface | 1 : 73.47 |
| Firebox/Tube surface | 1 : 11.01 |
| Total/Superheater | 1 : 5.39 |
