These allowed a user to put the Antikythera mechanism into motion by carefully rotating a knob. This portable machine was incredibly capable. It predicted eclipses according to a Babylonian cycle ...

Cams are used to convert rotation into linear motion ... and demonstrates it’s use with a cam follower, locking mechanism, cam plate, and a knob that snaps to predefined positions.

Yet how exactly the mechanism might ... like face boasted rotating, bejeweled hands that depicted the movement of planetary objects. Users would wind the hands with a knob or handle on its side.