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Class 114 Derby 2-car DMUs

Power Train

The first 48 power cars were built with the then standard BUT 150hp engine, although this was the first use of the Leyland 680 rather than the AEC 220 as fitted to the Lightweights. The rest of the power train was the same, being coupled to a SCG gearbox and AEC F239C final drive. The original underframe layout is seen below (on 50001).

Class 114 with Leyland 150hp engine

While there had already been many power trailer sets already in traffic which were successful, the longer heavier steel bodies meant a lower power / weight ratio.


The final power car to be built, delivered around a year after the first, was fitted with the newly developed Albion 230hp engines (also supplied under the BUT badge), each fitted with a 20" fluid flywheel. They drove a SCG SE4 gearbox and RF28 final drive. This was an experiment in an attempt to overcome the insufficency of power which had been found where fairly severe gradients and tail loads were met.

Class 114 with Albion 230hp engine

The second image shows the BUT Albion 230hp engine newly fitted to 50049. The easiest difference in telling the two engine types apart is the exhaust manifold is below the rocker covers on the Albion, above on the Leyland. The radiators also differed, the conventional 150hp radiator was square and the bigger version was rectangular with a bar down the centre.

The coupling code was the same, yet it had provision made for the fitting of fully-automatic gear control, which would relieve the driver of having to do appropriate gear changes (this system was also applied to Derby Lightweight 79135 in 1957).

After testing it was announced at the start of 1958 that the rest of the class would be fitted with the Albion engines. By late summer '58, 50048 became the 2nd car to receive the new equipment. It wasn't the end of experimenting though, the drive train equipment after re-enginning become:

Vehicles BUT DTO No. Engines Gearboxes Final Drives
No.1 Position No.2 Position
Type List No. Type. List. No. Type List No.

50001-50024 1/35 Leyland 900/6 SE4 6494 SE4 6494 RF28 6489
50025 1/42 Leyland 900/9 SE3 (R17) 6718 SE3 (R17) 6718 RF28 6727
50026-50031 1/35 Leyland 900/6 SE4 6494 SE4 6494 RF28 6489
50032 1/42 Leyland 900/9 SE3 (R17) 6718 SE3 (R17) 6718 RF28 6727
50033-50047 1/35 Leyland 900/6 SE4 6494 SE4 6494 RF28 6489
50048 1/28A Leyland 900/2 SE4 5744 SE4 5744 RF28 6489
50049 1/28 Leyland 900/2 SE4 6085 SE4 6085 RF28 6489

Also fitted to E50025 & E50032 - 17 in. D.F. Torque Converter, List No. 6793 and V.S. Control Equipment (Generator) List No.6947

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