Abstract: Drive member for timepiece movement comprising: a barrel comprising a drum mounted on an arbor; a main spring wound inside the barrel, and a core coaxial with and pivoting on the arbor; the exterior end of the spring being coupled to the drum and the interior end of the spring being coupled to the core; the exterior end of the spring is coupled to the drum by a first clamp that is pivot-mounted in the drum so that when the spring is unwound, the first clamp pivots in such a way as to hold the exterior turn of the first spring against the drum and when the spring is wound up, the first clamp pivots towards the center of the barrel to follow the exterior turn of the spring. The bending stresses in the spring are reduced.

Abstract: The oscillating mass able to be fixed to a frame (1) pivoted on the exterior of a timepiece movement has toothing kinematically connected to the ratchet of a barrel of the timepiece movement. This oscillating mass has, on the one hand, a mount (4) which is annular or is in the form of an annular sector and is able to be fixed to the frame (1) and, on the other hand, a central part (7) located mainly or exclusively in one half of the surface delimited by the mount (4).

Abstract: The oscillating mass able to be fixed to a frame (1) pivoted on the exterior of a timepiece movement has toothing kinematically connected to the ratchet of a barrel of the timepiece movement. This oscillating mass has, on the one hand, a mount (4) which is annular or is in the form of an annular sector and is able to be fixed to the frame (1) and, on the other hand, a central part (7) located mainly or exclusively in one half of the surface delimited by the mount (4).