On soil plate compactors (like the Wacker type)I have 7.5 Robin motor. These motors drive via a belt a small vibrator unit which makes the whole unit vibrate. We have tried with and without clutches on the` motors.The result is always the`same, broken woodruff keys !Its strange that the Honda motors dont do this as much! These are E spec Robin motors!

Why do the woodruffs always break?

Does having the centrifugal clutch on make it easier or harder for the woodruffs to break?

Is the problem linked to shutting the motor off when it is running full tilt and using the electrical cut off button? hence the vibratory unit spins faster than the motor and the sudden jolt brakes the key?

Any solutions?

thnx