Cam 1 rotates about fixed axis A and has four profiled ridges. Follower 6 reciprocates in fixed guides B-B and carries four rollers, 2, 3, 4 and 5. When cam 1 rotates counterclockwise, rollers 2, 3, 4 and 5 roll along cam ridges a, b, c, d, e, f and g, reciprocating follower 6. When rollers 2 and 3, 3 and 4, and 4 and 5 roll along ridges a, b and c, respectively, follower 6 travels downward. Follower 6 has a dwell when rollers 4 and 5 roll along ridge d which is concentric to the shaft of cam 1. When rollers 5 and 4, 4 and 3, and 3 and 2 roll along ridges e, f and g, respectively, follower 6 travels upward. Positive motion is achieved because the distance between the theoretical, or pitch, curves of the two sides of each ridge is equal to the distance between the centres of adjacent rollers.
$3093$SmC,ML$