In order to provide a master cylinder, in particular for a clutch system, an actuating system or a braking system of a vehicle, which enables secure sealing of the cylinder chamber relative to the outside, as well as a reliable flow of hydraulic medium into the cylinder chamber, it is proposed that the piston comprises a first section which has a cylindrical lateral surface and a second section which has at least one region which is set back radially inwardly with respect to the cylindrical lateral surface of the first section, wherein at least one set-back region extends to an end of the piston and wherein the first and second sections are arranged on the piston in such a way that in an actuating position of the piston, the main sealing element in the first section of the piston abuts in sealing manner thereagainst and in the pressure equalization position of the piston, in the second section of the piston between the piston and the main sealing element, at least one gap is formed, through which hydraulic medium can flow along the piston from the supply chamber into the cylinder chamber in order to equalize the pressure.

A master cylinder includes: a cylinder housing; a piston which is movably disposed in the cylinder housing so as to form a pressure chamber and a hydraulic fluid supplying chamber; and a sealing member which is interposed between the cylinder housing and the piston. An indentation portion is provided on an outer circumferential surface of the piston, wherein a rear wall of the indentation portion is formed as a slanted surface. A plurality of first communication holes are formed on a bottom surface of the indentation portion and a second communication hole is formed on the rear wall of the indentation portion.

Disclosed herein is a hydraulic master cylinder body having a bore defined at least in part by a bore wall, wherein the bore wall includes an opening for hydraulic fluid to be passed into the bore, and a piston assembly situated at least substantially in the bore, the assembly having a piston with a piston body and at least one cup seal situated substantially around the piston body, the cup seal situated adjacent to the bore wall so as to be in sealing engagement therewith, and a back-up ring that is situated about the piston body, wherein the back-up ring is positioned to at least partially cover a portion of the cup seal that is adjacent to the bore wall and to prevent at least a portion of the cup seal from contacting the bore wall and the opening for hydraulic fluid during piston actuation.

Disclosed herein is a hydraulic master cylinder body having a bore defined at least in part by a bore wall, wherein the bore wall includes an opening for hydraulic fluid to be passed into the bore, and a piston assembly situated at least substantially in the bore, the assembly having a piston with a piston body and at least one cup seal situated substantially around the piston body, the cup seal situated adjacent to the bore wall so as to be in sealing engagement therewith, and a back-up ring that is situated about the piston body, wherein the back-up ring is positioned to at least partially cover a portion of the cup seal that is adjacent to the bore wall and to prevent at least a portion of the cup seal from contacting the bore wall and the opening for hydraulic fluid during piston actuation.

A sealing element for sealing a pressure chamber is provided in a master cylinder for a clutch or brake system. The sealing element has a sealing lip for sealing a feed of hydraulic fluid from a reservoir mounted on a housing of the master cylinder into the pressure chamber and has a sealing structure for sealing the pressure chamber from the surroundings of the pressure chamber.

A sealing element for sealing a pressure chamber is provided in a master cylinder for a clutch or brake system. The sealing element has a sealing lip for sealing a feed of hydraulic fluid from a reservoir mounted on a housing of the master cylinder into the pressure chamber and has a sealing structure for sealing the pressure chamber from the surroundings of the pressure chamber.

A hydraulic brake master cylinder (12) for a vehicle braking system defines a first smaller fluid path (70, 50, 56, 34, 42, 44) and a second larger fluid path (72, 50, 56, 34, 44, 42) for connecting a working chamber (32) with a fluid reservoir at ambient pressure when the cylinder piston (28) is retracted and the brakes are not applied. A pressure relief valve (76) normally closes the second fluid path but is arranged to open when subject to a pressure differential at or above a threshold value. The first fluid path allows a restricted return flow of fluid to the reservoir should a standard knock-back event occur. If a larger knock-back event occurs causing a fluid pressure spike at or above the threshold value, the pressure relief valve (76) opens to allow a higher volume return flow through the second fluid path to dissipate the pressure quickly.

A hydraulic brake master cylinder (12) for a vehicle braking system defines a first smaller fluid path (70, 50, 56, 34, 42, 44) and a second larger fluid path (72, 50, 56, 34, 44, 42) for connecting a working chamber (32) with a fluid reservoir at ambient pressure when the cylinder piston (28) is retracted and the brakes are not applied. A pressure relief valve (76) normally closes the second fluid path but is arranged to open when subject to a pressure differential at or above a threshold value. The first fluid path allows a restricted return flow of fluid to the reservoir should a standard knock-back event occur. If a larger knock-back event occurs causing a fluid pressure spike at or above the threshold value, the pressure relief valve (76) opens to allow a higher volume return flow through the second fluid path to dissipate the pressure quickly.

Disclosed is a master cylinder. The master cylinder includes a hydraulic block provided with a main bore formed therein in an axial direction, a first piston having one side inserted into the main bore to be displaceable and the other side exposed to an outside of the hydraulic block and connected to a brake pedal, a second piston inserted into the main bore more inside than the first piston to be displaceable, an elastic member provided between the first piston and the second piston and configured to provide a pedal feel, and a mounting block provided with a sub bore formed therein in the axial direction and the sub bore where the first piston is inserted thereinto and passes therethrough to be displaceable and having one side coupled to the other side of the hydraulic block, wherein the hydraulic block includes at least one hydraulic flow path formed through the other side, and the mounting block includes a connection flow path allowing the sub bore to communicate with the hydraulic flow path.

A hydraulic braking system for a bicycle may include a hydraulic control device that is configured with multiple timing ports positioned within a stroke of a piston of the hydraulic control device. The multiple timing ports are located at different positions along an operational and/or axial length of a cylinder of the hydraulic control device.