Abstract: Brake master cylinder (10) for a motor vehicle, of the type which comprises a substantially axial body (12) inside a bore (14) of which at least one axial piston is slideably mounted, of the type in which the bore (14) comprises two seals, front (30, 34) and rear, interposed between the piston and the bore (14), the seals (30, 34) comprising three radially concentric lips accommodated in grooves (70, 72) in the bore (14), characterized in that the seals (30, 34) comprise central lips of reduced cross section.

Abstract: A pneumatic brake booster 1 comprising: a sealed structure 3 comprising a rigid casing 11 forming a funnel 19 furnished with an opening and a movable wall 13 dividing the sealed structure 3 into a low-pressure chamber 25 and a working chamber 27, a pneumatic piston 5 comprising a boss 31 fixedly attached to the movable wall 13 and mounted so as to slide in the funnel opening, a valve element 33 housed in the boss 31 and a seal 35 positioned between the boss 31 and the funnel 19, an input rod 7 and an output rod 9 coupled on either side of the pneumatic piston 5, and a return spring 37 to return the pneumatic piston 5 to a rest position, the return spring 37 being placed in the low-pressure chamber 25 between an internal surface 45 of the rigid casing and the pneumatic piston 5, and a force sensor 39 placed in the low-pressure chamber 25 and subjected to the pressure variations of the return spring 37.

Abstract: Master cylinder for a hydraulic braking circuit, particularly for a motor vehicle, comprising an annular seal (1) placed in a housing (6) of the body comprising an internal dynamic sealing lip (14) surrounding the piston, fitting into an annular groove (20) of the piston when this piston is in a rear rest position, an outer static sealing lip (10) pressing against a wall of the housing, and an additional static sealing lip (16) which presses against a wall of the housing of this seal and with the outer lip defines a small closed volume (V) of liquid.

Abstract: Master cylinder of a hydraulic braking circuit, particularly for a motor vehicle, comprising a piston (2) sliding axially in a body (4) comprising an annular lip seal (51) produced by molding, and comprising an internal, dynamic sealing lip (14) surrounding the piston and connected by a curved surface (36) to a planar rear face (30) comprising radial passages which are defined by blocks formed as projections on the rear face of the seal, these blocks being separated from the curved surface (36).

Abstract: The invention relates to a master cylinder (1) with reduced free travel (23). Current master cylinders have a free travel during the displacement of a piston (6) in a bore (5) of a master cylinder body (3). Such a free travel may be reduced with the aid of a frustoconical portion (24) in the piston, an orifice (14) for communication of hydraulic fluid being situated on said inclined wall, a gap (26) between the inclined wall and an inner wall (12) of the bore allowing a passage for hydraulic fluid capable of filling a pressure chamber (4). However, such inclined walls create a change in the slope of an outer wall (29) of the piston, this change being able to cause a separation of an inner lip (19) of a sealing cup (17). To prevent this separation, the invention provides that the inclined wall forms a convex rounded surface (32).

Abstract: Brake master cylinder (10) for a motor vehicle, of the type which comprises a substantially axial body (12) inside a bore (14) of which at least one axial piston is slideably mounted, of the type in which the bore (14) comprises two seals, front (30, 34) and rear, interposed between the piston and the bore (14), the seals (30, 34) comprising three radially concentric lips accommodated in grooves (70, 72) in the bore (14), characterized in that front faces of the grooves (70, 72) are configured at least in part as a slope.

Abstract: Brake master cylinder (10) for a motor vehicle, of the type which comprises a substantially axial body (12) inside a bore (14) of which at least one axial piston is slideably mounted, of the type in which the bore (14) comprises two seals, front (30, 34) and rear, interposed between the piston and the bore (14), the seals (30, 34) comprising three radially concentric lips accommodated in grooves (70, 72) in the bore (14), characterized in that the seals (30, 34) comprise central lips of reduced cross section.

Abstract: A pneumatic brake booster 1 comprising: a sealed structure 3 comprising a rigid casing 11 forming a funnel 19 furnished with an opening and a movable wall 13 dividing the sealed structure 3 into a low-pressure chamber 25 and a working chamber 27, a pneumatic piston 5 comprising a boss 31 fixedly attached to the movable wall 13 and mounted so as to slide in the funnel opening, a valve element 33 housed in the boss 31 and a seal 35 positioned between the boss 31 and the funnel 19, an input rod 7 and an output rod 9 coupled on either side of the pneumatic piston 5, and a return spring 37 to return the pneumatic piston 5 to a rest position, the return spring 37 being placed in the low-pressure chamber 25 between an internal surface 45 of the rigid casing and the pneumatic piston 5, and a force sensor 39 placed in the low-pressure chamber 25 and subjected to the pressure variations of the return spring 37.

Abstract: A master cylinder (1) having a bore (3) fitted with at least one piston (4, 5) and at least one seal (19, 20, 21, 22). The seal (19, 20, 21, 22) is partially stiffened by a reinforcement member (25). In order to retain the piston (4,5) in the bore (3) a groove (31) is located on a circumference of the piston (4,5) against which the sealing member (25) bears with the piston (4,5) in a rest position to retain the piston (4,5) in bore (3).