Abstract: On the basis of the engagement principle of the spatial curved surface, the engagement features of a new type spherical indexing cam mechanism is systematically studied by using rolating matrix operators. Some conclusions such as the instantaneous contact lines are line, the pressure angles are equal on each contact line, there is no relative sliding between cam and roller. The base of kinematics and geometry on this mechanism is set up.

Key words: Cam, Engagement, Indexing mechanism, Sliding, Velocity