This mechanism consists of a driven wheel with radial slots and a continuously rotating drive wheel equipped with a pin. As the drive wheel turns, the pin enters a slot and advances the driven wheel by one step, then exits the slot, leaving the driven wheel stationary until the next revolution. Engineers use it in indexing tables, automated assembly lines, and older film projectors to achieve precise, repeatable step-and-hold movements without complex electronics.
Check the pin on the drive side of the Geneva wheel because the indexing table is missing steps at high speed.
Because the pin engages the slot at a non-zero velocity, this mechanism experiences a sudden spike in acceleration, which can cause severe wear if run at high speeds without proper lubrication.
Also heard as
- Maltese cross mechanism
- Geneva stop
Do not mix it up with
- Escapement: An escapement releases stored energy in discrete steps to regulate speed, whereas a Geneva wheel converts continuous input rotation into discrete output rotation.