Cam 1 rotates about fixed axis A and its surface, in which cam groove a-a is machined, is an internal spherical surface of radius r. Follower 2 oscillates about fixed axis B and carries roller 3 which rolls and slides along groove a-a. Roller 3 rotates about axis C. Axes B and C of follower and roller rotation intersect and are perpendicular to each other, as are axes A and B of cam and follower rotation. Thus, the axes of rotation of all the links intersect at a common point which is the centre of the spherical surface of radius r.
$3045$SmC,3L$