Three-lobe constant-breadth cam 1 rotates about fixed axis A. Contour a of cam 1 is enclosed by a square opening of follower 2 which has claw b and straight slot d. Slot d slides along member 3 which turns about fixed axis B. When cam 1 rotates, follower 2 has a complex motion in which claw b is inserted into a perforation of the film, advances the film and is withdrawn from the perforation.
$3108$SmC,OC$