Cam 1 rotates about fixed axis A and its contour a is composed of three portions: a concentric circular arc of radius r within central angle φ, a straight line within central angle ψ and semicircular recess b within angle θ. Follower 2 turns about fixed axis B and carries roller 3 which rolls along contour a of cam 1. When cam 1 rotates clockwise, follower 2 has a rapid drop, then a slow rise and, finally, a long dwell. When cam 1 rotates counterclockwise, follower 2 has a long dwell, then a slow fall, and finally, when roller 3 enters recess b, follower 2 is locked. Roller 3 is held in contact with cam 1 by spring 4.
$3015$SmC,3L$