A system for maintaining brake cylinder pressure includes a brake cylinder passage configured to be in fluid communication with a brake cylinder, a brake pipe passage configured to be in fluid communication with a brake pipe and a brake cylinder, a first valve member moveable between a first position and a second position, and a second valve member in fluid communication with a reference pressure. The second valve member is configured to move the first valve member from the first position to the second position based on a differential between a pressure within the brake cylinder passage and the reference pressure, where the brake pipe passage is configured to only supply air from a brake pipe to a brake cylinder when the first valve member is in the second position.

A low-pressure vehicle braking system and method of operation that controls the supply of brake fluid based on the pressure differential between left and right master cylinders associated with the different wheel brakes allowing for pressure harmonization between the left and right wheel brake circuits and a brake system module suitable for installation on an existing vehicle.

A wheel brake apparatus for implementing a braking operation via a hydraulic service brake and for implementing a braking operation via an electromechanical parking brake includes at least two pressing elements and a brake caliper. The at least two pressing elements are configured for achieving a braking effect by way of pressing a brake lining against a brake disk. The brake caliper is configured for supporting the at least two pressing elements. The service brake and the parking brake have separate pressing elements. The pressing element of the service brake and the pressing element of the parking brake are attached to the same brake caliper.

A overrun brake system includes a gas spring with a gas-tight cylinder and a piston with holes allowing gas to slip through so that the pressure is the same on both sides. Since the free end of the piston has a larger area than the side where the piston rod is located, the gas spring will act as a compression spring. To prevent the overrun brakes from being activated during reversing, the gas spring has a solenoid controlled valve receiving current from the reverse light circuit and closing the flow of gas through the piston when the towing unit's gear is set into reverse. When the gear is set into forward position the solenoid loses its current and a mechanical return spring opens the valve, so that the overrun brakes may act normally again.

A method of controlling an electromechanical brake system. The method comprises measuring a voltage of a motor, measuring a current of the motor, and estimating a position of a component of the electromechanical brake system based on the voltage and the current. The method comprises estimating a force imposed by the component based on the voltage and the current, and estimating a hydraulic pressure associated with a hydraulic brake system. In an apply operation, the force of the component is corrected based on the hydraulic pressure. In a release operation, the position of the component is corrected based on the hydraulic pressure.

When an ON operation of an electric parking brake apparatus is performed when a vehicle is moving, a vehicle brake control apparatus executes an EPB stop process in order to stop the vehicle by braking force generated by a hydraulic brake apparatus. If a hydraulic brake malfunction wheel, at which the hydraulic brake apparatus cannot generate braking force properly, is detected during a time period from the beginning of the EPB stop process to the stop of said vehicle, the vehicle brake control apparatus makes the hydraulic brake apparatus stop generating braking force at wheels including the hydraulic brake malfunction wheel. Meanwhile, the vehicle brake control apparatus makes the electric parking brake apparatus start generating braking force at a rear wheel. Subsequently, the vehicle brake control apparatus makes the electric parking brake apparatus start generating braking force to the other rear wheel.

When an ON operation of an electric parking brake apparatus is performed when a vehicle is moving, a vehicle brake control apparatus executes an EPB stop process in order to stop the vehicle by braking force generated by a hydraulic brake apparatus. If a hydraulic brake malfunction wheel, at which the hydraulic brake apparatus cannot generate braking force properly, is detected during a time period from the beginning of the EPB stop process to the stop of said vehicle, the vehicle brake control apparatus makes the hydraulic brake apparatus stop generating braking force at wheels including the hydraulic brake malfunction wheel. Meanwhile, the vehicle brake control apparatus makes the electric parking brake apparatus start generating braking force at a rear wheel. Subsequently, the vehicle brake control apparatus makes the electric parking brake apparatus start generating braking force to the other rear wheel.

A brake retarder valve for a tractor-trailer combination includes a valve housing and a valve assembly. The valve assembly includes a poppet valve biased by a spring and a gravity spool. The valve assembly is selectively operable between the operative closed configuration and an open configuration in response to a resultant of the fluid pressure between a trailer axle brake and a tractor axle brake. The tractor axle brake is actuated with a time delay from actuation of the trailer axle brake. This delay is actuation of the tractor axle brake prevents jack knifing of the trailer onto the tractor in a tractor-trailer combination, thereby ensuring safety during operation of a tractor-trailer combination.

A stroke-controlled balancing device for hydraulic braking systems, comprising a balancing duct, a normally closed balancing valve, configured, in use, to maintain a connection between the hydraulic braking system and the balancing duct either closed or open, a stem having an external surface and an internal surface. A balancing channel is provided on the internal surface of the stem, said channel being hydraulically connected to the balancing duct, and the balancing valve is configured to slide, in use, along the external surface of the stem in order to open the connection between the braking system and the balancing duct. A braking system comprising the balancing device, as well as a method of operation of the braking system, are also described.

Disclosed is a hydraulic control apparatus of a brake system including a modulator block having a motor bore, and a motor including a cover that covers an opening of a case accommodating a stator and a rotor and is supported on one side of the modulator block, wherein a vent hole for air flow between the inside and the outside of the motor is formed on the cover and a communication passage for communicating the motor bore and the vent hole is formed in the modulator block.