Tie-rod 5 transmits oscillating motion to cam 1 about fixed axis A. Follower 2 oscillates about fixed axis B and carries two rollers, 3 and 4, which roll along working surface a of cam 1. Positive motion is achieved because the distance C͞D between two points lying on the theoretical, or pitch, curve (not shown) is equal for all positions of centres C and D of rollers 3 and 4.
$3087$SmC,ML$