Cylinder cam 1 rotates about fixed axis A-A and has profiled helical ridge a. Follower 2 reciprocates in fixed guides B-B whose axis D-D is parallel to axis A-A. Follower 2 carries two rollers 3 which roll along the upper and lower side surfaces of ridge a. Positive motion is achieved because the vertical distance between the theoretical, or pitch, curves of the side surfaces of ridge a is constant and equal to the distance between the centres of rollers 3. The type of motion of the follower depends upon whether helical ridge a has a constant or variable pitch.
$3036$SmC,3L$