Geneva Mechanisms

A Geneva Mechanism, sometimes known as a Geneva Drive, is a frequently used mechanism designed to produce rotary motion intermittently from a uniform speed of input. The driven part – the star wheel – features slots which the roller of the driving crank fits into. Essentially, as the drive wheels turns and begins to enter the star wheel slots, motion commences. The driven wheel will be indexed as the pin leaves the slot and will remain stationary until the pin rotates through again. The number of slots of a Geneva Mechanism determines the ratio between the stationary period (the dwell) and the motion period. Three slots are the minimum requirement, but more may be added. The basic principle of a Geneva Mechanism is used widely across many applications, such as in mechanical watch mechanisms. For industry, any machine that is indexable may utilise a Geneva Mechanism, such as lathes and screw machines.