Slipping gear / clutch gear for RC cars

A slipping gear is a very simple torque limiting device like the torque limiter of a drill.

Why would you want that, and particularly in a RC car, which has an electrical brushless motor?

One use case could be to protect the motor in case the output gets blocked while you continue to throttle … 

But the reason I designed this was to be able to sense that the car was entering a steep incline for instance (or rough terrain) to be able to switch to low gear, thus decreasing speed but increasing output torque.

Like my printed shock absorbers, there is some tuning to be done… My very first design would not slip (!) the part named “AGA60-01-Clutch” slips quite easily and the part named “AGA63-01-Clutch 2” is an alternative (stronger) part and slips at a higher resistance.

This sub-assembly is supposed to be blocked in place on both sides by other parts inside the my automatic 2 speed gearbox (to come), that's why there is no specific fastening of parts.

I'm providing a small axle you can tighten in your drill while holding the gear to test the slippage. (set the drill on the lowest possible torque)

The gear is a left 20 teeth helical gear (angle 30°) with a module of 1.5 mm that is suitable for the gearbox but the ring and the clutch could be adapted to any gear (provided it's big enough).

Printing tips: @ 0.20

Print the clutch in PETG (it needs to flex and accept some heat - so PETG is better than PLA).

The other parts can use PLA.