50000 / 56000 Derby 2-car DMU

Description - transmission

This vehicle's hydraulic torque converter was based in the American twin disc type. It had operational differences from the Leyland - Lysholm Smith type in use at the time fitted to the West Riding Derby Lightweights. On these earlier cars manual change of the controls was necessary when the driver wished to isolate the torque converter and chance to direct mechanical drive. On 50000 this change was automatic.

The control system was designed by Rolls Royce and was not compatible with any other vehicles at the time. It used a Westinghouse variable air pressure throttle control.

The cut-away drawing below shows the items on the drive train, numbered 4 - 8.

The internal layout and design appears to be identical to the Class 114 vehicles.

In 1958 there were 100 Cravens vehicles ordered for the LMR each fitted with the same 238hp Rolls Royce engine. Half were to be built with torque converters (supplied by Rolls Royce) and half with gearboxes (supplied by BUT). A common control system was needed to ensure the different types would operate together and be compatible with other Blue Square units. Rolls Royce and BUT both submitted proposals, with the Rolls Royce system being chosen. To test this system, 50000 and 56000 were converted to Blue Square at Derby Works at the end of 1958. Some notes on the conversion can be found in this letter (incomplete).

Livery

The set was delivered in lined green with the lion over wheel British Railways logo (only the power car 50000) and without whiskers. The cab dome was nominally white although appears more grey in the works photograph when taken on the Wirksworth branch. It also had white tyres brightening up the otherwise black underframe equipment.

The vehicles would have received whiskers and then a yellow panel on the cab ends, the livery it would probably be withdrawn in.