How can I power a wheel but let it spin freely when not under power?
I saw the question How can I modify a low cost hobby servo to run 'freely'? but I'm more interested in knowing if there is some sort of gearbox that disengages ( moves to 'neutral' ) when no torque is being applied to it.
Two ideas that come to mind are:
A drive gear on a spring loaded arm with a nominal amount of resistance before engaging. Perhaps when under power it would first use power to move in one direction, then it would engage with another gear, but without power the spring would return it to a non-engaged position
A centrifugal clutch - although I'd like something that works at low RPMs as well
The idea is to create a small bot that can move up and down a track, but if someone interacts with it when not under power it will just roll and won't damage the gearbox.