Abstract: In this reverser mechanism the winding wheel is assembled on a common axis with two ratchet wheels each assigned to one of the pivoting direction of the oscillating mass.The winding wheel is pierced by rivets which bear respectively a pawl and a spring. The spring which is thus mounted on a pivot means of a pawl cooperating with one of the ratchet wheels loads the pawl which cooperates with the other ratchet wheel.The mechanism is for use with timepieces having automatic winding of the mainspring.