Cylinder cam 1 rotates about fixed axis A-A and has helical groove a with right- and left-hand portions of constant pitch. Follower 3 reciprocates along fixed guide 4 and carries pivoted lens-shaped member 2 which slides along groove a. When cam 1 rotates at constant speed, follower 3 travels at constant velocity. At its extreme positions, follower 3 is automatically reversed, being switched over from right- to left-hand portions of the groove or vice versa. This provides for continuous motion of follower 3. Axis B-B of follower travel is parallel to axis A-A.
$3039$SmC,3L$