A new approach to the kinematical analysis of universal joints

In this paper, universal joint is treated from the viewpoint of the theory of mechanisms, and firstly, its degree of freedom as a spherical mechanism is calculated and discussed. Then, two different systems which are used to transmit rotational motions, are kinematically analysed. The first of these systems consists of two shafts connected via a universal joint, while the other comprises of three shafts and two universal joints connecting them. For both systems, the relationships between rotation angles of shafts are derivated by applying the rigidity condition on the cross arms.