A brake pedal unit includes a housing defining a bore formed therein. An input piston is slidably disposed in the bore. The input piston is connected to a brake pedal such that engagement of the brake pedal causes movement of the input piston within the bore of the housing of the brake pedal unit. The brake pedal unit is defined to be in an at rest position when the brake pedal in not engaged causing movement of the input piston. A primary piston is slidably disposed in the bore for pressurizing a primary chamber. A primary passageway permits fluid communication between the primary chamber and the reservoir, wherein fluid flow through the primary passageway is blocked when the brake pedal unit is in the rest position. A secondary piston is slidably disposed in the bore for pressurizing a secondary chamber. A secondary passageway permits fluid communication between the secondary chamber and the reservoir, wherein fluid flow through the secondary passageway is blocked when the brake pedal unit is in the rest position

A master cylinder and an electronic brake system including the same are disclosed. The electronic brake system includes a main hydraulic-pressure supply device to generate hydraulic pressure by sensing displacement of a brake pedal and a sub hydraulic-pressure supply unit to supply hydraulic pressure to at least one wheel cylinder during an abnormal operation of the main hydraulic-pressure supply device. The master cylinder includes a first piston disposed in a bore of a cylinder body so as to be directly pressurized by the brake pedal, a first hydraulic chamber pressurized by the first piston to discharge hydraulic pressure, a second piston indirectly pressurized by the first piston, and a second hydraulic chamber pressurized by the second piston to discharge hydraulic pressure. The second hydraulic chamber includes a slippage prevention means connected to the sub hydraulic-pressure supply unit so as to prevent the second piston from moving toward the first piston by the hydraulic pressure received from the sub hydraulic-pressure supply unit.

A master cylinder and an electronic brake system including the same are disclosed. The electronic brake system includes a main hydraulic-pressure supply device to generate hydraulic pressure by sensing displacement of a brake pedal and a sub hydraulic-pressure supply unit to supply hydraulic pressure to at least one wheel cylinder during an abnormal operation of the main hydraulic-pressure supply device. The master cylinder includes a first piston disposed in a bore of a cylinder body so as to be directly pressurized by the brake pedal, a first hydraulic chamber pressurized by the first piston to discharge hydraulic pressure, a second piston indirectly pressurized by the first piston, and a second hydraulic chamber pressurized by the second piston to discharge hydraulic pressure. The second hydraulic chamber includes a slippage prevention means connected to the sub hydraulic-pressure supply unit so as to prevent the second piston from moving toward the first piston by the hydraulic pressure received from the sub hydraulic-pressure supply unit.

An emergency braking device including an actuator (2), a pressurizing circuit (3) supplying the actuator (2) via a control pressure and a discharge circuit (4). The discharge circuit (4) includes restrictors (13, 14) for controlling the pressure and/or flow rate of the supply fluid of the actuator (2) during a discharge of the actuator. The restrictors (13, 14) are configured to define an intermediate pressure between a low pressure level and the control pressure of the actuator (2).

An emergency braking device including an actuator (2), a pressurizing circuit (3) supplying the actuator (2) via a control pressure and a discharge circuit (4). The discharge circuit (4) includes restrictors (13, 14) for controlling the pressure and/or flow rate of the supply fluid of the actuator (2) during a discharge of the actuator. The restrictors (13, 14) are configured to define an intermediate pressure between a low pressure level and the control pressure of the actuator (2).

A hydraulic block of a slip regulation of a hydraulic vehicle power brake system that has a master brake cylinder bore and forms a master brake cylinder. In order to prevent a hard impact of a piston of the master brake cylinder against an end stop when the master brake cylinder is released, in particular when there is an abrupt release, for example when the foot slides off a foot brake pedal, a hydraulic return damper that is integrated in the piston is provided.

A braking system for vehicles having a master cylinder, and at least one braking device. The master cylinder may be provided with a first and a second output circuit, containing respectively a first and second brake fluid. The first output circuit may be fluidically connected to a braking simulator and the second output circuit may be fluidically connected to the at least one braking device for its actuation. An automatic hydraulic actuation unit operatively connected to the master cylinder by a hydraulic actuation circuit traversed by an actuation fluid distinct from the first and second brake fluid may be provided. A processing and control unit of the system that supervises the operation of the braking systems may also be provided.

A braking system for vehicles having a master cylinder, and at least one braking device. The master cylinder may be provided with a first and a second output circuit, containing respectively a first and second brake fluid. The first output circuit may be fluidically connected to a braking simulator and the second output circuit may be fluidically connected to the at least one braking device for its actuation. An automatic hydraulic actuation unit operatively connected to the master cylinder by a hydraulic actuation circuit traversed by an actuation fluid distinct from the first and second brake fluid may be provided. A processing and control unit of the system that supervises the operation of the braking systems may also be provided.

A system and method for controlling wheel brakes on a trailer in a tractor-trailer are provided. Upon receiving a command to apply a trailer wheel brake, the system determines a speed of the tractor-trailer responsive to a speed signal generated by a vehicle speed sensor. The system also estimates a threshold speed based on a level of friction between the tractor-trailer and a road surface on which the tractor-trailer is travelling. The system then generates a control signal to control delivery of fluid pressure to the trailer wheel brake. The control signal causes delivery of a first fluid pressure to the trailer wheel brake when the speed meets a predetermined condition relative to the threshold speed and a second fluid pressure, less than the first fluid pressure, when the speed does not meet the predetermined condition.

A system and method for controlling wheel brakes on a trailer in a tractor-trailer are provided. Upon receiving a command to apply a trailer wheel brake, the system determines a speed of the tractor-trailer responsive to a speed signal generated by a vehicle speed sensor. The system also estimates a threshold speed based on a level of friction between the tractor-trailer and a road surface on which the tractor-trailer is travelling. The system then generates a control signal to control delivery of fluid pressure to the trailer wheel brake. The control signal causes delivery of a first fluid pressure to the trailer wheel brake when the speed meets a predetermined condition relative to the threshold speed and a second fluid pressure, less than the first fluid pressure, when the speed does not meet the predetermined condition.