SR Leader class
| SR/BR Leader class |
| Type and origin |
| Power type |
Steam |
| Designer |
Oliver Bulleid |
| Builder |
SR Brighton Works |
| Build date |
1946–1949 |
| Total produced |
5 (only one completed) |
|
| Specifications |
Configuration:
|
|
| • Whyte
|
0-6-0+0-6-0 |
| • UIC
|
C′C′ h6t |
| Gauge |
4 ft 8 1⁄2 in (1,435 mm) standard gauge
|
|
Driver dia. |
5 ft 1 in (1.549 m) |
| Length |
67 ft (20.42 m) |
| Loco weight |
150 long tons (168 short tons; 152 tonnes) |
| Fuel type |
Coal |
| Fuel capacity |
4 long tons (4.5 short tons; 4.1 tonnes) |
| Water cap |
4,000 imp gal (18,000 l; 4,800 US gal) |
Firebox:
• Firegrate area |
25.5 sq ft (2.37 m2) |
| Boiler pressure |
280 lbf/in2 (1.93 MPa) |
| Cylinders |
Six (Three in each bogie) |
| Cylinder size |
12 1⁄4 in × 15 in (311 mm × 381 mm) |
|
|
|
|
|
| Type and origin |
| Power type |
Steam |
| Designer |
Oliver Bulleid |
| Builder |
SR Brighton Works |
| Build date |
1946–1949 |
| Total produced |
5 (only one completed) |
| Specifications |
Configuration:
|
|
| • Whyte
|
0-6-0+0-6-0 |
| • UIC
|
C′C′ h6t |
| Gauge |
4 ft 8 1⁄2 in (1,435 mm) standard gauge
|
|
Driver dia. |
5 ft 1 in (1.549 m) |
| Length |
67 ft (20.42 m) |
| Loco weight |
150 long tons (168 short tons; 152 tonnes) |
| Fuel type |
Coal |
| Fuel capacity |
4 long tons (4.5 short tons; 4.1 tonnes) |
| Water cap |
4,000 imp gal (18,000 l; 4,800 US gal) |
Firebox:
• Firegrate area |
25.5 sq ft (2.37 m2) |
| Boiler pressure |
280 lbf/in2 (1.93 MPa) |
| Cylinders |
Six (Three in each bogie) |
| Cylinder size |
12 1⁄4 in × 15 in (311 mm × 381 mm) |
The Leader was a class of experimental 0-6-0+0-6-0 articulated steam locomotive, produced in the United Kingdom to the design of the innovative engineer Oliver Bulleid. The Leader was an attempt to extend the life of steam traction by eliminating many of the operational drawbacks associated with existing steam locomotives. It was intended as a replacement for the ageing fleet of M7 class tank engines still in operation on the Southern Railway (SR). Design work began in 1946 and development continued after the nationalisation of the railways in 1948, under the auspices of British Railways (BR).
The Leader project was part of Bulleid's desire to modernise the steam locomotive based on experience gained with the Southern Railway's fleet of electric stock. Bulleid considered that attitudes towards the labour-intensity of steam operation had changed during the post-war period, favouring dieselisation and electrification. In an effort to demonstrate the continued potential of steam, Bulleid pushed forward the boundaries of steam-power, allowing it to compete with diesel and electric locomotives in terms of labour-saving and ease of operation.
The design incorporated many novel features, such as the use of thermic siphons, bogies and cabs at each end of the locomotive, resulting in its unique—for a steam locomotive—modern diesel-like appearance. Several of its innovations proved to be unsuccessful however, partly accounting for the project's cancellation in the early 1950s. Five Leader locomotives were begun, although only one was completed. The operational locomotive was trialled on the former Southern Railway network around Brighton. Problems with the design, indifferent reports on performance and political pressure surrounding spiralling development costs, led to all locomotives of the class being scrapped by 1951.
The basis of the Leader originated from a 1944 review of the Southern Railway's steam locomotive fleet, resulting in a Southern Railway design brief which called for a high-powered locomotive requiring little maintenance to replace the ageing fleet of M7 class tank engines. The brief also stipulated that the locomotive would be used on both passenger and freight trains, requiring high route availability. Bulleid proposed an initial design based on his SR Q1 class locomotive, which had proved easy to maintain in service. As the proposal progressed, Bulleid saw that certain tasks required with conventional steam locomotives could be eliminated by adopting some of the features of the contemporary Southern electric locomotives. However, one of the subsequent designs of a 0-4-4-0 wheel arrangement had an unacceptably high axle-loading of 20 long tons (20.3 tonnes; 22.4 short tons), which increased the risk of damaging the Southern Railway's track. By developing the proposal further, Bulleid settled for a 0-6-0+0-6-0 design of bogied tank locomotive, which spread the weight more evenly over the rails and reduced the axle-loading.
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Wikipedia
