A diagnostic method for a bicycle hydraulic disc braking system, having a master cylinder assembly with a cylinder inside which a piston reciprocates against the action of a return spring. The master cylinder has a hydraulic tank with a bottom, a ceiling, and a membrane that divides the hydraulic tank into two chambers. The hydraulic tank is connected to the cylinder through the bottom. A metering device measures the distance between the membrane and the ceiling of the tank. The output signal of the metering device is evaluated to determine that operation is correct when the membrane temporarily approaches the ceiling by a predetermined extent range, or incorrect otherwise. A positive evaluation reflects the correct operating condition, and a negative evaluation reflects an incorrect operating condition.

A master cylinder for a brake may include: a cylinder housing a first piston installed in the cylinder housing, and movable by an operation force received from a brake pedal; and a second piston within the cylinder housing, and movable in connection with the first piston, wherein the first piston comprises: a first piston body partially within the cylinder housing; and a booster connection within the direction opposite to that in which the first piston body faces the second piston, integrated with the first piston body, and connected to a booster so as to receive the operation force of the brake pedal.

A hydraulic master apparatus for a hydraulic brake or clutch of handlebar-guided vehicles having a handlebar tube includes a support, a lever pivotally connected to the support, a hydraulic cylinder sized to fit in the handlebar tube and having a piston, and a pulling device configured to exert a pulling force on the piston when the lever is actuated. The apparatus also includes a grip width adjusting apparatus, by which a distance between the support for the lever and the hydraulic cylinder is adjusted to adjust a grip width. Also included is a cover that, responsive to being connected in the handlebar tube, defines with the hydraulic cylinder in the handlebar tube a compensating chamber therebetween.

An electro-hydraulic brake system comprises a single-circuit master cylinder (MC) fluidly coupled to a first MC fluid passageway and configured to supply fluid into the first MC fluid passageway in response to pressing force on a brake pedal coupled thereto. The electro-hydraulic brake system also comprises a pressure supply unit (PSU) assembly including an electric motor coupled to a ball screw actuator, a PSU housing defining a piston bore having a terminal end opposite the electric motor, and a PSU piston disposed within the piston bore and movable by the ball screw actuator through the piston bore and dividing the piston bore into a first chamber and a second chamber, with each of the first chamber and the second chamber containing a hydraulic fluid. The ball screw actuator includes an actuator nut assembly having a plurality of ball bearings each disposed within the piston bore and submerged in the hydraulic fluid.

The actuating device for a vehicle brake system comprises a force input member, which can be coupled to a brake pedal, and a brake master cylinder. The brake master cylinder has at least one force transmission member. The force transmission member is coupled to the force input member in an articulating fashion. The force transmission member is positioned to transmit a force, which has been exerted onto the force input member, to the brake master cylinder. The actuating device has at least one elastically deformable positioning element. The at least one positioning element produces a holding force with which the at least one positioning element holds the at least one force input member in an installation position relative to the brake master cylinder.

One embodiment provides a hydraulic pressure generation apparatus including: a base body; a motor; a reservoir tank; a master cylinder which generates a brake hydraulic pressure by a brake manipulator; and a slave cylinder which generates a brake hydraulic pressure the motor. The base body includes: a first cylinder hole which is a bottomed cylinder hole, and in which the first piston is inserted; a second cylinder hole which is a bottomed cylinder hole, and in which the second piston is inserted; and a supply passage which leads from the reservoir tank to a hydraulic chamber of the slave cylinder. The supply passage is provided with a check valve which permits only inflow of brake fluid from the reservoir tank to a side of the slave cylinder, near a brake fluid discharge port of the second cylinder hole.

A hydraulic pressure generating device includes a base body having a master cylinder configured to generate a brake hydraulic pressure and a slave cylinder configured to generate a brake hydraulic pressure. The base body is provided with a motor configured as a driving source for the slave cylinder and a control device configured to control the motor. A motor shaft of the motor, a cylinder axis of the master cylinder, and a cylinder axis of the slave cylinder are disposed in parallel with each other. Then a virtual plane including the cylinder axis of the master cylinder is set as a reference plane, a housing of the control device is disposed on one side of the reference plane and the motor is disposed on the other side of the reference plane.

A hydraulic pressure generating device includes a base body, a master cylinder provided on the base body and configured to generate a brake hydraulic pressure by a first piston connected to a brake operating element, a housing attached to the base body, a control board contained in the housing, a stroke sensor configured to detect an amount of movement of the first piston; and a detection object member which is detected by the stroke sensor. The housing has a facing wall portion provided so as to face the base body. The stroke sensor is provided inside the housing on the opposite side of the facing wall portion to the base body, and is electrically connected to the control board.

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 master cylinder for a hydraulic brake system or clutch system, in particular of a vehicle steered by handlebars, in particular of a bicycle, includes a housing containing a piston chamber. The housing accommodates a piston slidable therein and a pressure chamber. A compensating chamber communicates with the pressure chamber through at least one compensating bore. The housing has an attachment portion for attachment to a handlebar tube and the compensating chamber extends to the attachment portion and has a separating member for separating the hydraulic fluid from a compensating volume. The attachment portion has a clamping part made and arranged to attach the separating member to the attachment portion.