British Rail Class 43 (HST)

The British Rail Class 43 (HST) is the TOPS classification used for the InterCity 125 High Speed Train power cars, built by BREL from 1976 to 1982.

The class is the fastest diesel unit in the world, with an absolute maximum speed of , and a regular service speed of . There are claims that this diesel rail speed record has been broken twice unofficially: by a Russian train in 1992 achieving , and a Spanish train reporting in 2002. Railway Gazette International August 2002

History and background

In the early 1970s the British Railways Board (BRB) decided to replace their main-line express diesel traction. Financial limitations were tight, so mass electrification was not possible. As a result, a new generation of high-speed diesel trains had to be developed.

Experience with the high-speed Class 55 Deltic locomotives had shown that a low axle weight was essential to avoid damage to the track at sustained high speed, and that high-speed engines were the only way to provide a good enough power/weight ratio for diesels. To power the HST at up to , each power car had a new diesel engine, the 12-cylinder Paxman Valenta, running at 1,500 rpm and developing . The 70-tonne weight of the power car gave it a 17.5-tonne axle loading.

Development and design

The prototype set was developed at the Railway Technical Centre, Derby, the power cars having been constructed by BREL Crewe Works and the British Rail Mark 3 passenger cars by BREL at Derby Litchurch Lane......
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