Cam 1 rotates about fixed axis A and its working surface consists of a continuous vee-groove, making several turns, which engages corresponding grooves in follower 3. The grooves in follower 3 are not continuous, but are separate annular grooves. Over a certain angle φ, corresponding to portion a-a of the working surface, the vee-grooves are deflected to one side a distance equal to the pitch of the grooves. Portion a-a is along a circular arc described from centre A. When cam 1 rotates, link 2 with follower 3 turns about fixed axis B until the ridges of portion a-a of the cam engage the grooves of follower 3. Then link 2 has a dwell in its oscillating motion but begins to slide along guides b-b a distance equal to one pitch of the grooves. Thus the motion of link 2 consists of oscillation with a dwell about axis B and a horizontal indexing motion, parallel to axis A, equal to one pitch per revolution of cam 1.
$3083$SmC,ML$