Abstract: A push-piece-crown (1) mounted on a guide tube (T) secured in a case (C) housing a timepiece, and fixed in rotation as well as axially to a control stem (TR) adapted to occupy at least two axial positions, of which a first ("0") is stable and a second ("-1") is transitory, comprising a head (2) fixed to said stem and mounted to be axially movable on said tube (T), and a return spring (8) bearing at one end on said head (2) for urging it towards said stable position, in which said spring (8) also bears at its other end on an annular abutment (9) movable within said head (2) between said stable position, in which said abutment (9) bears on a shoulder (13) on the interior of said head (2) and said transitory position, in which the abutment (9) rests on a shoulder (E3) of said tube (T).

Abstract: In order to open the watch case (1) by extraction of the crystal (2) such case is secured in an enclosure (3) after its stem and crown have been removed. Next, a suction cup (4) is applied to the crystal, such suction cup being maneuverable from outside the enclosure by means of a handle (40). By means of a pump controlled by a lever (37) the enclosure is subjected to a predetermined overpressure, following which a pulling force (A) is exerted on the suction cup until extraction of the crystal. The overpressure being the same at both the exterior and interior of the case, no displacement of air is brought about and hence no damage to the watch mechanism when the crystal is separated from the case.

Abstract: This pushpiece (1) for a timepiece includes a movable head (3) slidingly mounted on a tube (4), said head partially enveloping such tube. The head exhibits a central cylindrical core (5) which penetrates into the tube, at least one O ring seal (6) being located between the tube and the core. A return spring (7) urges the head towards the exterior. The core (5) is extended by a stem (8), the diameter of which is greater than the diameter of the core, the spring being arranged between the stem and the tube. In this manner the spring is located in a sealed zone of the pushpiece and the mean diameter of the O ring seal is less than the mean diameter of the spring.

Abstract: This valve (1) for a watch case comprises a head (3) and a tube (4) onto which the head can be screwed. A stem (8) fixed to a core (5) borne by the head is surrounded by a return spring (7) bearing, on the one hand, under the head and, on the other hand, onto a bottom (3) exhibited by the tube through a ring (14) and a first packing (6). A second packing (18) is mounted under the head in line with the tube. When the head is screwed down the second packing (18) is compressed and the valve is inoperative and at the same time totally sealed. When the head is unscrewed the first packing (6) is able to rise up against the return force of spring (7) if the fluid pressure prevailing within the case is higher than that on the exterior thereof. An excessive interior pressure which can damage the case is thus avoided.