Geneva Drive is a gear mechanism that translates rotation motion into intermittent rotary motion.
The rotating drive wheel has a pin that enters into the slot of driven wheel and make it rotate step by step. The driving wheel has also an elevated half circle that lock the driven wheel in position between steps.
The main difference between Geneva drive and other gears is that Geneva drive have unusual teeth. Unlike other gears ,in Geneva drive the interaction between the driving and the driven part is not continuous and the resultant motion is intermittent.
Working of Geneva Drive :-
In Geneva drive there are two wheels, driving and driven wheel. The driving wheel has a pin and a little more than semi circular disc which is elevated.
Image Source :- https://en.wikipedia.org/wiki/Geneva_drive
The driven wheel has 4, 6 or more slots in which the pin of driving wheel passes and rotates the driven wheel to angle depending upon number of slots. If it has 4 slots ,it will be rotated 90 degrees in one step and if it has 6 slots, it will be rotated 60 degrees at one step. The circular elevated disc is used to lock the driven wheel after each step.
Types of Geneva Drive:-
1) External Geneva Drive
2) Internal Geneva Drive
3) Spherical Geneva Drive
1) External Geneva Drive :-
In this External Geneva Drive, the driven wheel is connected with rotating drive wheel externally. This is the most popular Geneva Drive and used in many mechanical products like watch and film projector. It can withstand higher mechanical stresses.
2) Internal Geneva Drive :-
In Internal Geneva Drive, the driven wheel is connected with the rotating drive wheel internally.
Image Source : https://en.wikipedia.org/wiki/Geneva_drive
Both the driver and the driven wheel rotate in the same direction. Its disadvantage is that it cannot be built smaller and cannot withstand higher mechanical stresses like external Geneva drive .
3) Spherical Geneva Drive :-
In Spherical Geneva Drive, the driven wheel is in spherical shape and is connected to rotating drive wheel externally. In this driving and the driven wheel are on perpendicular shafts i.e input and output shafts are perpendicular to each other.
Applications of Geneva Drive :-
1) The most common application of Geneva Drive is Movie Projectors.
2) Bank Note Counting Machines
3) Automated sampling machines.
4) Plotters – Plotter is a computer printer for printing vector graphics.
5) Wrist Watches.