Two Station Geneva Mechanisms

Abstract

A conventional Geneva mechanism must have at least three radial slots (stations). This paper shows that it is possible to design a Geneva mechanism with only two slots, provided that the shape of the slot is not a straight radial line but a curved line. The design procedure of the two slot Geneva wheel is outlined in this paper. In addition, two different methods are provided to reduce the size of the slot and change its shape in order to make the mechanism feasible for practical applications. The reduction of the slot size is achieved either by choosing appropriate values for α0 , which is the half indexing angle of the crank, or by using the method of offsetting. The offsetting technique presents an excellent capability of suitably altering the slot shape without affecting the kinematic properties of the mechanism. The paper also shows the superior kinematic characteristics of Geneva wheels having two slots. The design and manufacture of these mechanisms are simple, and they have a good potential for wide ranging practical applications.