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 mechanism preventing rate variations caused by the effect of gravity on a regulating member (2, 3) of a timepiece movement comprises a regulating member comprising a balance-spring (2) and an escapement wheel (3) which are mounted on a platform (4). This platform (4) comprises an unbalance and is mounted so as to freely rotate about at least one first axis (A-A) with respect to a plate (1) of the movement so that the platform (4) rotates about said first axis (A-A) under the effect of the Earth's gravity. The mechanism comprises a going train comprising a kinematic drive chain (M) arranged to connect the escapement wheel (3) to a barrel system (10) of the timepiece as well as a kinematic correcting chain (C) which compensates for the displacements and speed of the platform (4) with respect to the plate (1).

Abstract: The method for regulating the time-keeping of a mechanical timepiece movement intended to operate in a low-pressure atmosphere, comprises the following successive steps: 1. placing the movement in a low-pressure atmosphere pre-established for normal operation of the movement, 2. measuring the gain or recoil (typically a gain +?P) of the time-keeping precision of the movement at this low pressure, 3. returning the movement to ambient atmospheric pressure, 4. regulating the movement to compensate for the previously measured gain or recoil (typically by performing a recoil ??P) in low-pressure operation, 5. returning the movement to atmosphere, at the low pressure pre-established for normal operation of the movement.