Lever 1, turning about fixed axis A, has hinged pawl 3 at point B. Segment 2 turns about axis A independently of lever 1. When lever 1 is turned clockwise, pawl 3 turns segment 2 in the same direction, tensioning flat spring 4. Pawl 3 is disengaged from the segment when its tip b runs up against pin a. After disengagement of pawl 3, segment 2 is turned by spring 4 in the reverse direction up to stop c.
$137$SL,L$