Class 74

In the late 1960s Southern Region required some more electro-diesels for the Bournemouth electrification scheme. Instead of building more Class 73s BR decided to rebuild 10 Class 71 DC electric locomotives as these could be more powerful than the Class 73s and rebuilds were thought to be cheaper than building new locomotives [1]. As with other Southern locomotives they could work in multiple with multiple units and other SR locomotives and be used for push-pull operations.

Number built: 10
Built: 1958-60 (Electric locomotives)
1967-68 (Rebuilds)
Builder: BR Doncaster, rebuilds at BR Crewe
Engine: 4 EE532A traction motors (750v DC third rail)
Paxman 6YJXL diesel
Power: 2, 300 hp (1, 715 kW) electric
650 hp (485 kW) diesel
Wheel arrangement: Bo-Bo

While the Class 74 seemed a great idea the execution let it down. The conversions were not simple with a lot of modifications and strengthening needed to fit the additional equipment [2]. Reliability in the early days was poor, the Paxman diesel not being as reliable as the English Electric unit in the Class 73, there were numerous problems with the complicated control equipment (the Class 74s were test beds for new thyristor controls [3]) and crews disliked the noise of the engine due to the location of the engine silencer near the cab.

By the late 1970s SR saw it had enough Class 33s and 73s to cover traffic requirements and the Class 74s were withdrawn by 1977 as non-standard. All have been scrapped though a Class 71 has been preserved.
74 009, location unknown (KD Collection)

[1] Brian Haresnape, Electric Locomotives (Ian Allan, 1983) p. 78
[2] David Brown, Southern Electric Vol 2 (Capital Transport, 2010) p. 220
[3] R.L. Vickers, DC Electric Trains and Locomotives in the British Isles (David & Charles, 1983) p. 81