The British Railways Standard Class 4 4-6-0 is a class of steam locomotives, 80 of which were built during the 1950s. Six have been preserved.

Background

The class was introduced in 1951. They were designed for mixed traffic use on secondary routes where the otherwise ubiquitous BR Standard Class 5 and their predecessors, the Black Fives, would be too heavy. They were essentially a tender version of the Class 4 2-6-4T, with similar characteristics to the GWR 7800 Class, though unlike the 7800s they were built to the universal loading gauge. They used the same running gear as the tank engine (with the leading bogie from the Standard Class 5), and substantially the same firebox, smokebox and boiler, although the boiler barrel was increased in length by 9 in. Design work was done at Brighton by R. A. Riddles, with help from Swindon, Derby and Doncaster. Construction was at the BR Swindon Works. The engine weighed 67.90 LT, was 60 ft long, with 5 ft diameter driving wheels. It had two cylinders of 18 in diameter and 28 in stroke operated at maximum boiler pressure of 225 lbf/in2, to produce 25515 lbf tractive effort. Its British Railways power classification was 4MT. It normally used the standard BR2 or BR2A tender, which weighed 42.15 LT and carried 3500 impgal of water and 6.00 LT of coal. In this configuration its route availability was 4, almost universal over the British Railways network.

In service

The class was initially allocated to the London Midland Region (45) and the Western Region (20). The last 15 were allocated to the Southern Region. The Southern batch were built with BR1B tenders, which weighed 49.15 LT, and carried 4725 impgal of water and 7.00 LT of coal. This reduced their route availability to 7, the same as the Standard Class 5.

Preservation

Six members of the class survive with both single chimney and double chimney examples. Two were purchased directly from BR (75027 & 75029); the remaining four were rescued from Woodham Brothers' scrapyard at Barry Island. No member of the class is presently main line approved but three (75014, 75029 and 75069) have worked on the main line at various points in preservation. 75029 was passed to work on the main line between Grosmont and Whitby with occasional visits to Battersby during galas. All except for 75079 have operated in preservation.

Model railways

Bachmann and Hornby have both recently released models of these engines in 00 gauge. Mainline Railways also released a OO gauge model of the Standard Class 4MT 4-6-0 in the 1970s, although this is no longer in production. In 1983, Mainline's model was reintroduced to their catalogue as locomotive 75033 in BR lined black.