A valve system includes an isolation check valve delivering pneumatic fluid as a supply pressure, a double-check valve adapted to deliver a braking demand control signal of the pneumatic fluid based on a higher of a first braking demand in a first pneumatic braking circuit and a second braking demand in a second pneumatic braking circuit, and a control module. The control module is adapted to receive the supply pressure as a control module supply pressure of the pneumatic fluid, receive a control module control pressure of the pneumatic fluid based on the braking demand control signal, and deliver a control module delivery pressure of the pneumatic fluid based on the control module supply pressure and the control module control pressure. A park control module selectively transmits the pneumatic fluid at the supply pressure based on a park brake control signal.

A valve system includes an isolation check valve delivering pneumatic fluid as a supply pressure, a double-check valve adapted to deliver a braking demand control signal of the pneumatic fluid based on a higher of a first braking demand in a first pneumatic braking circuit and a second braking demand in a second pneumatic braking circuit, and a control module. The control module is adapted to receive the supply pressure as a control module supply pressure of the pneumatic fluid, receive a control module control pressure of the pneumatic fluid based on the braking demand control signal, and deliver a control module delivery pressure of the pneumatic fluid based on the control module supply pressure and the control module control pressure. A park control module selectively transmits the pneumatic fluid at the supply pressure based on a park brake control signal.

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.

A brake system having a wheel brake and being operable under a non-failure normal braking mode and a manual push-through mode. The system includes a master cylinder operable by a brake pedal during the manual push-through mode to provide fluid flow at an output for actuating the wheel brake. A first source of pressurized fluid provides fluid pressure for actuating the wheel brake under the normal braking mode. A second source of pressurized fluid generates brake actuating pressure for actuating the wheel brake under the manual push-through mode.

A brake system for motor vehicles has a master brake cylinder having at least a first and a second master brake cylinder piston, arranged one behind the other and bound a first and second pressure space. Wheel brakes are connected to each a brake circuit. The first master brake cylinder piston is connected to a brake pedal via a pressure rod. An atmospheric pressure medium storage tank is assigned to the pressure spaces at, per brake circuit, an electrically controllable pressure source with a suction connection and a pressure connection. The pressure connection connected to the wheel brakes. The suction connection connected to the master brake cylinder via a normally closed valve, and, per brake circuit, a normally open valve via which the master brake cylinder is connected to the wheel brakes. Per brake circuit, the suction connection is connected to the pressure medium storage tank via a first valve.

A brake system for motor vehicles has a master brake cylinder having at least a first and a second master brake cylinder piston, arranged one behind the other and bound a first and second pressure space. Wheel brakes are connected to each a brake circuit. The first master brake cylinder piston is connected to a brake pedal via a pressure rod. An atmospheric pressure medium storage tank is assigned to the pressure spaces at, per brake circuit, an electrically controllable pressure source with a suction connection and a pressure connection. The pressure connection connected to the wheel brakes. The suction connection connected to the master brake cylinder via a normally closed valve, and, per brake circuit, a normally open valve via which the master brake cylinder is connected to the wheel brakes. Per brake circuit, the suction connection is connected to the pressure medium storage tank via a first valve.

When a brake system on a commercial vehicle, lateral acceleration and/or yaw of the vehicle are monitored and compared to a first predetermined threshold. If the first predetermined threshold is exceeded, a precharge command is sent to the brake system to precharge one or more air chambers by temporarily deactivating a modulator valve and activating an antilock traction relay valve in order to charge the air chambers up to a level permitted by the modulator valve. Upon detecting a panic braking event, a command signal is sent to the brake system to release the precharged air to facilitate braking.

When a brake system on a commercial vehicle, lateral acceleration and/or yaw of the vehicle are monitored and compared to a first predetermined threshold. If the first predetermined threshold is exceeded, a precharge command is sent to the brake system to precharge one or more air chambers by temporarily deactivating a modulator valve and activating an antilock traction relay valve in order to charge the air chambers up to a level permitted by the modulator valve. Upon detecting a panic braking event, a command signal is sent to the brake system to release the precharged air to facilitate braking.

A brake modulator (1) for a compressed air braking system (80) of a vehicle is disclosed. The brake modulator (1) has a main housing (8) and two relay valves (2, 3). Each relay valve is configured with a delivery valve seat (31, 131) and a vent valve seat (30, 130) and a vent position, wherein compressed air inlets (2d, 3d) are connected via a transverse bore (27) to a common compressed air inlet port (25, 26), and a delivery duct (12a, 112a) extends in the axial direction (A) in each relay valve (2, 3). The relay valves (2, 3) have guide body inserts (12, 112) which are inserted into a longitudinal bore (29) of the main housing (8), which longitudinal bore (29) extends in the axial direction (A), and the relay valves (2, 3) in each case have the delivery duct (12a, 112a).