Cam 1 rotates about fixed axis A and its working surfaces consist of two curvilinear portions a-a and b-b, and two concentric circular arcs c-c and d-d, described from centre A. Cross-shaped follower 2 rotates about fixed axis B and carries rollers 3, 4, 5 and 6 which roll along the inner and outer working surfaces of cam 1. When cam 1 rotates through angle ψ follower 2 turns through the angle φ. The first half of this turning motion is accomplished by the action of portion a-a of the cam surface on roller 3, and the second half by the action of profiled groove b-b on roller 4. Upon further rotation of cam 1 through the angle 360°-ψ follower 2 has a dwell during which rollers 3, 4, 5 and 6 roll along outer and inner concentric circular arcs c-c and d-d of cam 1, thereby preventing unintentional rotation of follower 2.
$3099$SmC,ML$