Cam 1 rotates about fixed axis A and has groove a with three points of self-intersection of the theoretical, or pitch, curve of the groove. Follower 2 reciprocates in fixed guide B and carries pivoted lens-shaped member 3 which slides along groove a. Groove a has three helical turns of constant pitch for slow motion of follower 2 to the right at constant velocity. From its extreme right-hand position, follower 2 travels rapidly to its extreme left-hand position because member 3 slides along portion b of the groove. This portion is a helical half- turn milled in the rear half (as shown) of the cylindrical surface of cam 1.
$3053$SmC,3L$