Barrel for automatic winding time piece, has friction surfaces that are limited on downstream face with respect to sliding direction of outer turn through round salient angle or sharp or round reentrant angle

摘要

The barrel has a circular drum (10) including an inner side wall (11) with friction surfaces (12) alternating with notch-shaped locking structures (16) to form a round salient angle and a round or sharp salient angle at the limit of the surfaces. A main spring (20) forms a winding with an outer turn (21), which is coupled with the friction to the wall and free to slide against the wall in case of over voltage of the main spring. The surfaces are limited on a downstream face with respect to sliding direction of the outer turn via the round salient angle or sharp or round reentrant angle (18b). An independent claim is also included for a time piece comprising an automatic winding movement.