Cam 1 reciprocates along fixed guides a-a and has a profiled ridge. Follower 2 reciprocates in fixed guides B-B and carries two rollers, 3 and 4, which roll along side surfaces, b and c, of the ridge on cam 1. The centres D and E of rollers 3 and 4 lie on axis d-d of follower motion. Positive motion is achieved because the distance between the theoretical, or pitch, curves of surfaces b and c, along any vertical, is constant and equal to D͞E, the distance between the centres of rollers 3 and 4.
$3025$SmC,3L$