Worm 1 rotates about fixed axis B and meshes with worm wheel 6 whose bearing 5 can turn about fixed axis A. Plate cam 2 is rigidly attached to worm wheel 6 and has a working surface along an Archimedean spiral. Slide 3 can be moved along fixed guides a-a. Slide 3 mounts roller 7 which contacts cam 2. Slide 3 can be precisely set by turning worm 1. Spring 4 eliminates backlash in the worm gearing. The weight of slide 3 holds roller 7 in contact with cam 2.
$3301$GrC,ML$