The British Railways Standard Class 4 tank is a class of steam locomotive, one of the BR standard classes built during the 1950s. They were used primarily on commuter and outer suburban services. They were capable of reaching speeds of .
Background
On the nationalisation of British Railways (BR) in 1948, the London Midland Region had a number of ex-London, Midland and Scottish Railway 2-6-4T and the Western Region a number of GWR Large Prairie 2-6-2T types. These tank engines were particularly suited to commuter and secondary services. However, particularly in Scotland and the Southern Region, the situation was not so good, with large numbers of pre-grouping types struggling on.
Design and construction
On the decision to build the BR standard series of locomotives, a series of class four tank engines was ordered, based on the ex-LMS Fairburn 2-6-4T with some modifications. The lineage of the class could therefore be tracked through the LMS/BR Class 4 2-6-4T locomotives back to the Fowler design of 1927.
Design work was done at Brighton, the overall programme being overseen by Robert Riddles. The principal modifications to the Fairburn design involved the reduction of their envelope to enable them to fit into the L1 loading gauge. To do this, the tanks and cab were made more curved than the Fairburn design, the Fairburn having a straight-sided tank. The biggest mechanical change was a reduction in cylinder size, also to reduce cross-section, and a corresponding increase in boiler pressure to compensate. Other visible changes included the re-introduction of plating ahead of the cylinders.
130 of the class of 155 were built at Brighton, 15 (80000–80009, 80054–80058) at Derby Works and 10 (80106–80115) at Doncaster Works between 1951 and 1956. The first to emerge was 80010 from Brighton in 1951. Fifteen that were due to be constructed in 1957 were cancelled, due to impending dieselisation, and the last five would have been, too, had they not been at an advanced stage of construction when the order came to cancel them.
No significant modifications were made to the design. The tank vent was found to restrict the driver's vision and was moved further forward from 80059 onwards. Initially built with fluted coupling rods, these caused problems on other classes and, from 80079, plain section coupling rods were substituted.
The BR Standard Class 4 4-6-0 was essentially a tender engine derivative of the Standard Class 4 tank.
Service
The Standard 4 tanks were originally allocated to all regions of British Railways, bar the Western. They became particularly associated with the London, Tilbury and Southend line (LT&S) working commuter services out of London, until that route was electrified in 1962. They were also widely used in East Sussex and Kent, working from Brighton, Tunbridge Wells and Three Bridges on those lines of the former London Brighton and South Coast Railway that were not electrified. Another group worked from Polmadie depot in the Scottish region on the Glasgow commuter services. Note that, from July 1962, a batch displaced by electrification of the LT&S was transferred to the Western Region's Swansea (East Dock) and Shrewsbury districts, as well as other regions.
Accidents and incidents
On 24 April 1956, locomotive No. 80119 was derailed at , Yorkshire when the track spread under it whilst shunting. An instruction banning heavy locomotives from shunting at Scalby had been forgotten. On 30 January 1958, locomotive No. 80079 was hauling a passenger train that overran signals and was in a rear-end collision with another passenger train at , Essex. Ten people were killed and 89 were injured. On 18 April 1961, locomotive No. 80075 was hauling a passenger train that was derailed at Pitsea, Essex due to a pointsman's error during single line working. On 9 December 1962, locomotive No. 80102 was derailed at , Hampshire due to vandalism.
Withdrawal
There was a mass withdrawal of steam locomotive classes in the 1960s. Older types were withdrawn in preference to the Standard 4s, whose class remained intact until 1964 (except for 80103 as noted below). The final nine were withdrawn from the Southern Region on 9 July 1967. One Scottish Region example, 80002, remained in Glasgow past the end of steam haulage until 1969 as a static carriage heating boiler; eventually being preserved on the Keighley & Worth Valley Railway.