Pushy props

[Simon Chaddock]

Just a point about pushy props and bearings. The prop thrust on the engine will be reversed so any motor (electric or i.c.) with ball bearings should be no problem but a plain bearing engine (older i.c.) might not be designed to take reverse prop thrust.

[Alistair Taylor]

Spot on Simon

Some manufacturers of IC engines )and electric motors come to think of it) put a thin steel thrust washer between the prop driver and crankcase. This reduces the wear you would otherwise get when the aluminium prop driver is pushed against the aluminium crankcase if the engine is run in pusher mode; as is the case with cox babe bee engines, which will generate a grey-black aluminium paste around the crankcase/prop driver until the wear is such that the crankshaft hits the reed valve holder. The higher performance cox tee dees came with a thrust washer I believe which avoided this.

AlistairT