South African class HF
The class HF was a 2-8-2+2-8-2 Modified Fairlie that did not only have two driving axles more than the preceding classes FC and FD, but also a higher axle loading. The class designation should have been “FE”, but obviously “HF” was chosen to denote it as a “Henschel Fairlie” in contrast to the other Fairlies built by North British. It had a direct competitor in the class GE Garratt with the same wheel arrangement that was introduced two years earlier.
When put into service, they had some problems with steam production which had to be addressed in the Durban Workshops. A general problem of Modified Fairlies were the overly long frames which did not only have to carry the boiler, but also the supplies. So there were often cracks in the frames and also the pivot bearings were subject to a huge amount of wear and tear. So all in all, they were not as successful as the Garratts and no further Modified Fairlies were ordered by the SAR. The eleven class HF locomotives were withdrawn by 1951.
Technical data
General
- Built
- 1926-1927
- Manufacturers
- Henschel
- Wheel arrangement
- 2-8-2+2-8-2T (Modified Fairlie)
- Gauge
- 1,067 mm (Cape gauge)
Dimensions and weights
- Length
- 12.64 m
- Wheelbase
- 21.29 m
- Service mass
- 152.5 t
- Adhesion mass
- 104.5 t
- Rigid wheelbase
- 3.89 m
- Axle load
- 13.3 t
- Water capacity
- 20,911 l
- Fuel capacity
- 9.1 t (coal)
Boiler
- Grate area
- 4.924 m²
- Firebox surface
- 19.417 m²
- Tube heating surface
- 191.566 m²
- Evaporative heating surface
- 210.983 m²
- Superheater surface
- 55.556 m²
- Total heating surface
- 266.5 m²
Power plant
- Driver diameter
- 1,168 mm
- Boiler pressure
- 12.4 bar
- Expansion type
- simple expansion
- Cylinders
- four, 457 x 610 mm
Power
- Power source
- steam
- Estimated power
- 1,193 kW (1,622 PS)
- Starting effort
- 230.1 kN
Calculated values
- Factor of adhesion
- 1 : 4.45
- Optimal speed
- 32 km/h
- Power-to-weight ratio
- 7.8 kW/t
- Heating Surface Equivalent
- 419.2 m²
- Cylinder volume/HSE
- 1 : 955.01
- Adhesive weight/Total
- 1 : 1.46
- Tractive force/Heating surface
- 1 : 18.03
- Grate area/Heating surface
- 1 : 54.13
- Firebox/Tube surface
- 1 : 9.87
- Total/Superheater
- 1 : 3.80