Recycled Detritus - The Clutch and Gears
by Dave Watkins
How the clutch works and reduction gears
A flywheel is fixed to the engine crankshaft. A simple disc clutch is pressed against the end face of the flywheel by a coil spring. The nut holding the flywheel to the crankshaft sits in a recess in the flywheel so does not get in the way of the clutch.
The clutch pressure plate consists of a disc of brass to which a disc cut from model aircraft plywood is glued. This plywood forms the friction surface.
The clutch is carried on a sliding shaft running through the gearbox. It carries a pinion which meshes with a large cog to provide the first stage speed reduction. The pinion is long enough to allow for the shaft to slide to and fro.
The clutch is operated by a lever which projects out of the top of the gearbox. This lever is forked at the bottom end to fit round the sliding shaft. The lever rocks about a pivot arranged above the shaft. When the top of the lever is pushed towards the engine, the fork presses on a collar pinned to the sliding shaft. This releases the clutch. Letting go of the lever engages the clutch.
As orginally built, a simple catch held the clutch operating leaver in the release position. Moving the catch engaged the clutch and the loco would move away. Pushing the operating lever forward released the clutch and engaged the catch. hence the locomotive would stand still with the engine idling.
Here is a sketch of the clutch mechanism. This is not to scale.
Another sketch showing how the reduction gears are arranged, again not to scale.
The clutch is now operated by radio control. The same servo operates the forward and reverse gear lever as well. I am hoping, in the near future, to add some pictures showing how the R/C has been fitted.
If you want to contact me about leisure activities Send e-mail to: dave.watkins@blueyonder.co.uk