Provided is a hydraulic unit of a brake system including a housing; an oil supply part configured to supply oil to the housing; an oil discharge part configured to discharge the oil, supplied to the housing through the oil supply part, to the outside of the housing; and a piston movably mounted on the housing, and configured to open and close the oil supply part and the oil discharge part.

Disclosed herein a caliper brake includes a carrier in which a pair of pad plates are installed to move forward and backward toward a disk; a caliper housing slidably installed on the carrier and provided with a cylinder; a piston installed in the cylinder and configured to move forward and backward toward the pair of pad plates by a braking hydraulic pressure; a seal member in close contact with an outer surface of the piston and an inner surface of the cylinder, the seal member having a ring-shaped; and a seal groove formed to be recessed in the inner surface of the cylinder to accommodate the seal member, the seal groove including a front braking surface facing a front surface of the seal member; wherein the front braking surface includes a protrusion protruding toward the seal member.

Disclosed herein a caliper brake includes a carrier in which a pair of pad plates are installed to move forward and backward toward a disk; a caliper housing slidably installed on the carrier and provided with a cylinder; a piston installed in the cylinder and configured to move forward and backward toward the pair of pad plates by a braking hydraulic pressure; a seal member in close contact with an outer surface of the piston and an inner surface of the cylinder, the seal member having a ring-shaped; and a seal groove formed to be recessed in the inner surface of the cylinder to accommodate the seal member, the seal groove including a front braking surface facing a front surface of the seal member; wherein the front braking surface includes a protrusion protruding toward the seal member.

A seal ring is an annular seal ring which is configured to be interposed between first and second members, and seals a gap between the first and second members. The second member is inserted into the first member, and reciprocates in its axial direction with respect to the first member. The seal ring includes an annular base part, an annular innermost end part, and a widening protrusion part. The annular base part has a radially exterior end to contact the first member. The annular innermost end part is integrally formed with a radially interior end of the base part to contact the second member. The widening protrusion part is integrally formed with the innermost end part, and protrudes with respect to the base part in the axial direction of the second member.

A piston assembly is provided for a human-powered vehicle. The piston assembly includes a main body and a primary seal. The main body is configured to be movable from a rest position to an actuated position along an actuation direction in a cylinder bore. The primary seal includes a primary seal body arranged on the main body. The primary seal body is made of a resin material. The primary seal body has a primary lip portion configured to be in contact with the cylinder bore in an arranged state where the piston assembly is arranged in the cylinder bore. The primary seal further includes a biasing part configured to be in contact with an outer circumferential surface of the main body to outwardly bias the primary lip portion of the primary seal body in the arranged state.

To provide a wire for a taper-faced compression ring, which can be provided with a running-in surface (contact surface) uniformly and rapidly in the production process of the taper-faced compression ring, a surface of the wire corresponding to an outer peripheral surface of the ring is provided with adjacent outward inclined first and second tapered portions, the inclination angle θ2 of the second tapered portion being larger than the inclination angle θ1 of the first tapered portion, and an outer end of the second tapered portion being located radially outward than an outer end of the first tapered portion by 0.005-0.05 mm. A long-life taper-faced compression ring with reduced friction and improved fuel efficiency is formed by the above wire, the second tapered portion having a lapped surface located radially outward than an outer end of the first tapered portion by 0.001-0.048 mm.

A combination hydraulic master cylinder comprising two typically parallel pumps disposed within adjacent compartments within a common body of the combination hydraulic master cylinder. Each pump's piston physically pressurizes hydraulic fluid that has been separately drawn into its respective cylinder and in hydraulic isolation, however the proximate location of the independent pumps allows for convenient operation using one hand on one handlebar with reduced congestion of space rather than the more conventional arrangement of two separate master cylinders. The pistons are actuated mechanically using dedicated levers mounted externally to the cylinders. The levers are adjustable in the manner to which they are disposed to the pistons. One lever is oriented such that it is operable using a finger pull action; the second lever is oriented such that it is operable using a thumb push action.

A combination hydraulic master cylinder comprising two typically parallel pumps disposed within adjacent compartments within a common body of the combination hydraulic master cylinder. Each pump's piston physically pressurizes hydraulic fluid that has been separately drawn into its respective cylinder and in hydraulic isolation, however the proximate location of the independent pumps allows for convenient operation using one hand on one handlebar with reduced congestion of space rather than the more conventional arrangement of two separate master cylinders. The pistons are actuated mechanically using dedicated levers mounted externally to the cylinders. The levers are adjustable in the manner to which they are disposed to the pistons. One lever is oriented such that it is operable using a finger pull action; the second lever is oriented such that it is operable using a thumb push action.

A guide ring for a pump element of a hydraulic unit of a vehicle brake system is configured to guide a pump piston in a pump housing when the pump piston is displaced along the axis thereof in the pump housing. On the inner side of the guide ring facing the pump piston, the guide ring includes a first step that has a first inner diameter and a second inner diameter.

A guide ring for a pump element of a hydraulic unit of a vehicle brake system is configured to guide a pump piston in a pump housing when the pump piston is displaced along the axis thereof in the pump housing. On the inner side of the guide ring facing the pump piston, the guide ring includes a first step that has a first inner diameter and a second inner diameter.