Wickham Railbus no DB999507 technical

The main engine is an unusual Meadows 6HDC500 diesel, these horizontal engines were fairly common in busses in the 1950s and quite a few Scammell lorries use the vertical version, but the company had ceased to exist by 1960 and only Wickham seem to have used the engines in rail vehicles.  

The drive is through a Wickham centrifugal clutch (rather than the more common fluid flywheel), four speed epicyclic gearbox with a separate reversing gearbox and a later speed reduction gearbox. The reduction box is unique (the drawings came with the vehicle) while the speed changing one is a four-speed Self Changing Gears R11 (a bus component) and the final drive is a standard Wickham one.

Gearbox and centrifugal clutch

The controls are similar to contemporary busses but with a hand throttle incorporating the deadmans handle.  

Driving controls (only this end has the handbrake)

The auxiliary engine is a two cylinder horizontally-opposed air-cooled Enfield diesel with a later 240v AC alternator, these are rather more common than the Meadows but still unusual and this has been out of use for some time so will need some work if it is decided to use it.

The brakes are Clayton-Dewandre straight air brakes based on road vehicle practice and only operate on the driven wheel this is a relic of the original measurement system where the free axle could not be allowed to spin or slip as this would spoil the distance and acceleration measurements.  There are no continuous brakes but there is an emergency valve and cylinder that operates if the main air pressure falls and the throttle lever incorporates a 'deadmans' valve.

The standard diesel-fuelled DMU heater was removed by the Middleton as it did not belong to the vehicle (it had electric heating towards the end of its research career).




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Copyright R. Hingley (2002-2010)