Three-lobe constant-breadth cam 1 and round eccentric constant-breadth cam 3 are rigidly attached together and rotate about fixed axis A. The contour of cam 1 is enclosed by the flat faces of slide 4 which reciprocates vertically along fixed guides b-b. The contour of cam 3 is enclosed by the flat faces of slide 2 which has pin d that reciprocates in guide f of slide 4 and has claw a. When cams 1 and 3 rotate, claw a is inserted into a perforation of the film, advances the film and is withdrawn from the perforation.
$3112$SmC,OC$