Pulley 1 turns about fixed axis A. Flexible link 3, usually designed as a steel belt, is attached at one end to pulley 1 at point D. At its other end, link 3 is connected by turning pair B to slider 2 which reciprocates in fixed guides a-a. When pulley 1 oscillates, slider 2 moves to the left when the pulley turns counterclockwise, and to the right when the pulley turns clockwise if the flexible link is sufficiently stiff. If not, pulley 1 is returned to its initial position by shifting slider 2 to the right.
$3482$SFL,4L$