Abstract: The present invention relates to a friction member comprising a support plate (26, 30) and a friction element (22, 24) arranged on one side of the support plate 26, 30), the friction element (22, 24) being adapted to engage one face of a rotating member (12), and at least one wear indicator (32) associated with the support plate (26, 30) so as to generate an audible signal when the friction element (22, 24) possesses, on account of its wear, a predetermined thickness (L). According to the invention, the wear indicator (32) is formed by a spring comprising an intermediate part (34) for fixing of the wear indicator (32) onto the support plate (26, 30) on the side of the latter which bears the friction element (22, 24), a first end part (36) for emission of the audible signal and a second end part (40, 50, 36') for locking of the wear indicator (32) in rotation with respect to the support plate (26, 30).

Abstract: A mobile pre-etched data carrier is provided in which the pre-etching is formed by a succession of discrete non continuous elements materializing the mean axis of the tracks. The spatial distribution of these discrete elements may be uniform or not. In a first embodiment, each discrete element is formed by a smooth track section. In a second embodiment, each discrete element comprises several sections defining a particular code. In other preferred variations of the invention, each element comprises, besides a portion centered on the mean axis of the tracks, one or more portions offset with respect to the axis. Finally, each of the pre-etchings may itself be preceded by an additional pre-etching element used for the purpose of synchronization. The tracking device comprises photodetector means, measuring circuits comprising sampler-inhibitors or storage integrator circuits and sampling circuits. A radial tracking error is formed from the evolution of the signals detected during successive passages.

Abstract: A mobile pre-etched data carrier is provided in which the pre-etching is formed by a succession of discrete non continuous elements materializing the mean axis of the tracks. The spatial distribution of these discrete elements may be uniform or not. In a first embodiment, each discrete element is formed by a smooth track section. In a second embodiment, each discrete element comprises several sections defining a particular code. In other preferred variations of the invention, each element comprises, besides a portion centered on the mean axis of the tracks, one or more portions offset with respect to the axis. Finally, each of the pre-etchings may itself be preceded by an additional pre-etching element used for the purpose of synchronization. The tracking device comprises photodetector means, measuring circuits comprising sampler-inhibitors or storage integrator circuits and sampling circuits. A radial tracking error is formed from the evolution of the signals detected during successive passages.

Abstract: A disc brake comprising a caliper straddling a rotary disc and carrying a pair of friction pads is disclosed. The friction pads are slidably received and anchor on guides defined by the circumferentially spaced edges of a radial aperture in the caliper. The caliper is slidably mounted on a fixed support member and carries a fluid pressure motor comprising a piston received in a cylinder and capable to occupy an idle position, an operating position closer to the disc than the idle position and a retracted position further from the disc than the idle position. Slots are provided in the guides to permit removal of the pads when the piston occupies its retracted position, and a detachable resilient clip is normally mounted on an axially extending portion of the cylinder between said cylinder and the adjacent pad to prevent the latter from moving back opposite the corresponding slot whatever the position occupied by the piston.