Abstract: A unit is formed by a winding ratchet (1) and a barrel arbor (4) having an end which includes a non-circular driving formation (5) and a groove (6) adjacent thereto that defines a small-section portion whose shape and dimensions are such that they extend into the section of the driving formation, whereby a shoulder (18) of the barrel arbor limits the height of the groove. The ratchet includes a central opening (2) corresponding to the driving formation and at least one off-centered tapping (3) relative to the ratchet. It includes an attachment washer (8) having a central passage (9) corresponding to the driving formation and engaged therewith in an assembled position, and at least one off-centered piercing (10), at least one screw for screwing the attachment washer onto the ratchet in a position angularly offset so that in this assembled position, the central opening is not aligned with the central passage.

Abstract: In order to counter the effects of the Earth's gravitational force on the operation of a watch movement, the timepiece includes an escapement mechanism designed to drive a finish gear-train of a watch movement which defines a reference plane, and a balance co-operating with the escapement mechanism. Particularly, the balance is mounted in a frame (28, 60), said frame pivoting about a first axis (AA, CC) relative to the reference plane, and the orientation of the frame (28, 60) relative to the first axis (AA, CC) depends on the orientation of the Earth's gravitational force.