A sub master cylinder includes a body formed with a chamber in which oil is stored; a first sub piston having one end which is secured to one end of the body and the other end which extends toward the other end of the body and is disposed to cross the chamber; and a second sub piston disposed between an inner surface of the body and an outer surface of the first sub piston to be moved in the chamber.

A master cylinder for a regulated braking system having at least one piston, which is movable in a housing and which is sealed from a pressure chamber by a sealing element arranged in a ring groove of the housing, which can be connected to an unpressurized supply chamber by control passages designed in the pistons. In order to reduce the flow resistance of the control passages at the same dead stroke, the control passages have a control edge designed parallel to a piston end face of at least one of the pistons.

A primary piston composed of a skirt and an intermediate back wall having a rear face receiving the servobrake thrust rod and a forward face for the telescoping rod and the spring pushing the secondary piston. The front of the skirt has longitudinal grooves open in front and closed in the rear. The thickness of the skirt beneath the grooves and the part of the skirt between two successive grooves in the peripheral direction form a front face enabling the principal piston to push the secondary piston. The principal piston is made of a single piece of plastic material.

A brake booster and related method for its operation for a vehicle, having a master brake cylinder having a first primary piston chamber that is variable using an adjustable first primary piston component, a braking force transmission component, using which at least one driver braking force is transmittable by the adjustable first primary piston component contacted by the braking force transmission component, and an adjustable second primary piston component, the master brake cylinder having a second primary piston chamber that is variable using the adjustable second primary piston component, and the brake booster has a booster force transmission component, using which a booster force from the actuator device is transmittable at least partially to the adjustable second primary piston component contacted by the booster force transmission component, and the braking force transmission component in its force-free initial position is distanced by a first free play from the first primary piston component and/or the booster force transmission component, in its force-free initial position, is distanced by a second free play from the second primary piston component.

A brake booster and related method for its operation for a vehicle, having a master brake cylinder having a first primary piston chamber that is variable using an adjustable first primary piston component, a braking force transmission component, using which at least one driver braking force is transmittable by the adjustable first primary piston component contacted by the braking force transmission component, and an adjustable second primary piston component, the master brake cylinder having a second primary piston chamber that is variable using the adjustable second primary piston component, and the brake booster has a booster force transmission component, using which a booster force from the actuator device is transmittable at least partially to the adjustable second primary piston component contacted by the booster force transmission component, and the braking force transmission component in its force-free initial position is distanced by a first free play from the first primary piston component and/or the booster force transmission component, in its force-free initial position, is distanced by a second free play from the second primary piston component.

A master cylinder includes pressurizing chambers and atmospheric pressure chambers which are in communication with a reservoir provided upstream. The pressurizing chambers of the master cylinder are connected to a brake fluid pressure control valve device through master pressure pipes provided with master cut valves. The atmospheric pressure chambers of the master cylinder bypass the master cut valves and are connected to the brake fluid pressure control valve device through bypass pipes provided with check valves. A pump constituting a brake fluid pressurizing section of the brake hydraulic control valve device suctions the brake fluid from the reservoir preferentially through the bypass pipes provided with the check valves and pressurizes the brake fluid to supply a brake fluid pressure to brake fluid pressure adjust sections.

A master cylinder includes pressurizing chambers and atmospheric pressure chambers which are in communication with a reservoir provided upstream. The pressurizing chambers of the master cylinder are connected to a brake fluid pressure control valve device through master pressure pipes provided with master cut valves. The atmospheric pressure chambers of the master cylinder bypass the master cut valves and are connected to the brake fluid pressure control valve device through bypass pipes provided with check valves. A pump constituting a brake fluid pressurizing section of the brake hydraulic control valve device suctions the brake fluid from the reservoir preferentially through the bypass pipes provided with the check valves and pressurizes the brake fluid to supply a brake fluid pressure to brake fluid pressure adjust sections.

A brake modulator (1) for providing an ABS brake function to a vehicle (200) includes a main body (17), a first ABS valve unit (47) configured to provide a first brake pressure (pB1) and a second ABS valve unit (53) configured to provide a second brake pressure (pB2), and a main cover (19) for closing of an assembly side (27) of the main body (17). The cover portions (127, 131, 133, 135) for covering corresponding valve cavities (33, 35, 37, 39) are formed separately from a main cover plate (20) of the main cover (19). A relay valve cover plate (137) is formed integrally with or separately from the main cover plate (20). The present disclosure further relates to a commercial vehicle (202) and to an assembly method (300) for a brake modulator (1).

A brake modulator (1) for providing an ABS brake function to a vehicle (200) includes a main body (17), a first ABS valve unit (47) configured to provide a first brake pressure (pB1) and a second ABS valve unit (53) configured to provide a second brake pressure (pB2), and a main cover (19) for closing of an assembly side (27) of the main body (17). The cover portions (127, 131, 133, 135) for covering corresponding valve cavities (33, 35, 37, 39) are formed separately from a main cover plate (20) of the main cover (19). A relay valve cover plate (137) is formed integrally with or separately from the main cover plate (20). The present disclosure further relates to a commercial vehicle (202) and to an assembly method (300) for a brake modulator (1).