The pure-rolling cam-equivalent of the Geneva mechanism

This paper deals with the kinematic synthesis of a pure-rolling cam mechanism kinematically equivalent to a conventional Geneva mechanism. This mechanism was designed as composed of a primary and a secondary mechanism, which work in parallel to produce an indexing motion on the driven link, identical to the wheel of the Geneva mechanism. The conjugate profiles of the primary mechanism are obtained from the centrodes of the relative motion of the Geneva mechanism. The cam profile of the secondary mechanism is obtained by assuming a suitable oscillating roller follower and imposing the same motion program that is given by the centrodes of the Geneva mechanism. Moreover, the Geneva mechanism is compared with its pure-rolling cam-equivalent from a static point of view by using the pressure angle as index of merit for the force transmission. Several numerical examples and simulations of their indexing motion are shown.