Cylinder cam 1 has continuous groove a-a of which, in end portion b, the bottom of the groove slopes gradually toward the outside of the cam. Slide 2 reciprocates in fixed guides of base 8. Roller 3 is mounted on plunger 9 which can slide in guide 10. Guide 10 is integral with slide 2. Levers 5 and 6 turn about axis A of slide 2 and are connected together by coil spring 7 which holds lever 5 against pin 13 in lever 6. Pin 12 in lever 6 slides a long slot 11 in plunger 9. When cam 1 rotates counterclockwise (looking from the right), slide 2 is traversed by roller 3 to the left until the roller reaches portion b of groove a-a and is forced out of the groove, pushing back plunger 9. As soon as the roller is disengaged from cam 1, slide 2 is rapidly returned to its right-hand position by a counterweight (not shown) on cable 4. This motion is limited by stop B on slide 2 and adjusting screw C in base 8. Just before slide 2 reaches its extreme right-hand position, lever 5 comes into contact with stop D on the base, swinging lever 6 upward and forcing roller 3 into the groove of cam 1 by the action of spring 7.
$3184$CmL,ML$