SAR class U
| SAR class U | |
|---|---|
 SAR class U
|
|
| Numbering: | 1370-1379 |
| Number: | 10 |
| Manufacturer: | Maffei |
| Year of construction (s): | 1927 |
| Retirement: | 1952-1957 |
| Type : | (1'C1 ') (1'C1') h4 |
| Gauge : | 1067 mm ( cape track ) |
| Length over coupling: | 23,062 mm |
| Service mass: | 167.2 t |
| Friction mass: | 111.7 t |
| Wheel set mass : | 18.9 t |
| Driving wheel diameter: | 1,219 mm |
| Impeller diameter: | k. A. |
| Cylinder diameter: | 470 mm |
| Piston stroke: | 660 mm |
| Boiler overpressure: | 124.1 N / cm² |
| Grate area: | 5.53 m² |
| Radiant heating surface: | 18.39 m² |
| Tubular heating surface: | 240.3 m² |
| Superheater area : | 56.7 m² |
| Train brake: | Suction air brake |
The U-class vehicles of the South African Railways (SAR) were articulated locomotives of the Union-Garratt design .
In contrast to real Garratts , these locomotives were a hybrid of Garratt and Modified Fairlie : the front water tank was built on the front bogie like a Garratt, while the coal box, like a Modified Fairlie, was mounted on the bridge frame, which also carried the boiler and driver's cab . A second water tank was hung under the boiler frame.
10 pieces were delivered by Maffei in 1927. In the same year the manufacturer also delivered the two Union-Garratts of the GH class . Why the one type with the designation "GH" was classified as a real Garratt and the other with "U" as a Union Garratt is no longer understandable today.
The class U locomotives were intended for freight train service on main lines and had the wheel arrangement (1'C1 ') (1'C1') and at 18.9 t the highest axle load of all South African articulated locomotives until then, later only of the GL class just outbid. However, their cylinders, which had turned out to be too small, prevented full utilization of the tractive force that was possible with it, while the high axle load limited the possible applications. As with the machines of the FC and FD classes , the large rear transition, compared to Garratts, led to greater wear on the pivot pins, which led to the class being withdrawn relatively early. The locomotives were equipped with a stoker , which was removed again in later years because it was not considered necessary for the services performed by the locomotives.
The locomotives were retired between 1952 and 1957. No copy has survived.
literature
- AE Durrant: Garratt locomotives of the world. Birkhäuser, Basel et al. 1984, ISBN 3-7643-1481-8 .