Pulley 1 rotates about fixed axis A-A. Pulley 3 has a spiral conical working surface and rotates about fixed axis B-B. One end of flexible link 2 is secured to pulley 1 at point C and the other end to pulley 3 at point D. When pulley 1 rotates at uniform speed, pulley 3 rotates at a nonuniform speed whose variation depends upon the profile of the spiral conical working surface. After the flexible link has been wound from pulley 3 onto pulley 1, pulley 3 becomes the driving link. Thus rotation of pulleys 1 and 3 is periodically reversed.
$3491$SFL,4L$