Cam 1 rotates about fixed axis A and consists of constant member a and adjustable member b which can be turned about axis C of the constant member by means of screw device 3 to change the working surface of cam 1 as a whole. Follower 2 reciprocates in fixed guides B-B and carries rollers 4 which roll a long the working surface of cam 1. When the working surface of cam 1 is changed, it is necessary to change the distance between the centres of rollers 4 by means of screw device 5 which displaces left-hand roller 4 a long the axis of follower 2. This adjustment retains positive motion.
$3138$SmC,LL$