Abstract: A brake system includes a tandem-type master cylinder, a tandem-type slave cylinder with front and rear fluid pressure chambers and front and rear pistons arranged such that fluid pressure is generated in the fluid pressure chambers when the rear piston is advanced by an actuator, wheel cylinders connected to the fluid pressure chambers of the master cylinder, respectively, and a regulator which regulates a maximum distance between the front and rear pistons. The regulator prevents excessive increase in the volume of the rear fluid pressure chamber.

Abstract: A brake system includes a tandem-type master cylinder, a tandem-type slave cylinder with front and rear fluid pressure chambers and front and rear pistons arranged such that fluid pressure is generated in the fluid pressure chambers when the rear piston is advanced by an actuator, wheel cylinders connected to the fluid pressure chambers of the master cylinder, respectively, and a regulator which regulates a maximum distance between the front and rear pistons. The regulator prevents excessive increase in the volume of the rear fluid pressure chamber.

Abstract: A brake system includes a master cylinder, a slave cylinder and a wheel cylinder for braking a wheel. The master cylinder and the slave cylinder are connected via a first and a second fluid passage. A shutoff valve is provided in the first fluid passage. The first fluid passage communicates with the slave cylinder at a position in front of an advance limit of a cup seal of a piston of the slave cylinder. The second fluid passage branches from the first fluid passage on a side of the master cylinder relative to the shutoff valve. When the shutoff valve is closed, stroke loss is automatically minimized from the time the piston starts to advance to the time brake fluid pressure is generated.

Abstract: When an electrical fluid pressure generator fails and a wheel cylinder is operated by brake fluid pressure generated by a master cylinder, if a first fluid pressure system leading to a rear fluid chamber of the electrical fluid pressure generator fails and is opened to the atmosphere, braking is performed by brake fluid pressure of a second fluid pressure system transmitted from the master cylinder through a front fluid chamber of the electrical fluid pressure generator to a wheel cylinder. At this time, a front supply port, which communicates through a front second cup seal facing rearward with the rear fluid chamber opened to the atmosphere due to the failure, does not communicate with the master cylinder but with a reservoir.

Abstract: A main object of the present invention is to provide a technique capable of improving the assembling performance of a double seal ring. According to the first embodiment of the invention, on the piston 31 side to which a seal ring is attached, there are provided a ring retaining portion 300 having an outside diameter L0 and for retaining a double seal ring 51, a first land portion 310 adjacent to the ring retaining portion 300 and having an outside diameter L1 (where L1>L0), and a second land portion 320 adjacent to an opposite side of the ring retaining portion 300 to the first land portion 310 and having an outside diameter L2 (where L2<L1). The outside diameter L2 of the second land portion 320 is set to be equal to or smaller than an inside diameter of the outer peripheral resin ring 55, and one side surface of the outer peripheral resin ring 55 on the side of the second land portion 320 is supported by a retainer ring 80 retained by the piston 31.