Constant-breadth cam 1 rotates about fixed axis A and is rigidly attached to gear 3 which meshes with gear 5, rotating about fixed axis B and rigidly attached to eccentric 4. Cam 1 is confined between the flat faces of yoke b of link 2 which carries claw a. Eccentric 4 is enclosed between the flat faces of yoke c of link 2 which has slot d sliding along fixed pin C. When cam 1 rotates, claw a of link 2 is inserted into a perforation of the film, advances the film and is withdrawn from the perforation.
$3330$GrC,OC$