Abstract: A master cylinder for use in a hydraulically actuated clutch or brake system of a motor vehicle, includes a casing formed with a bore, and a piston unit axially displaceable within the bore. The piston unit includes a piston-shaft sleeve received in the bore and having one end formed with a bottom to define an interior, at least two retainer shells received in the interior of the sleeve free of play, and a piston rod having a spherical head swingably mounted to the retainer shells and provided to respond to a manual actuation of a pedal. The retainer shells are each formed at a pedal-proximate end of the piston-shaft sleeve with a spherical recess to define a ball socket in which the spherical head snaps in and is received in form-fitting manner.

Abstract: A hydraulically actuatable device (1) for disengaging a gearshift clutch of an automotive vehicle, having an annular piston (4) arranged for sliding displacement with its inner peripheral surface (9) on a guide sleeve (6) and its outer peripheral surface (13) in a clutch output cylinder (2), a release bearing (5) positionally fixed by a disc spring (20) being lodged in an end of the annular piston (4) away from a pressure chamber (8), characterized in that, there is arranged on end of the annular piston (4) a fixing ring (12) comprising a cylindrical portion (14) which engages around a part of the outer peripheral surface (13) of the annular piston (4) to which it is fixed by positive engagement, and a radially inwards oriented arm (17) of an inner ring (16) of the release bearing (5) engages into a portion (15,45) of the fixing ring (12) having a U- or L-shaped cross-section and extending beyond end of the annular piston (4), arm (17) of the inner ring (16) being urged by the disc spring (20) supported on a