Abstract: The braking system of a vehicle is securely engaged in response to the operator of the vehicle causing the vehicle to stop. The vehicle being stopped is determined in response to several conditions including a predetermined time of stopping as well as suspensions settling time. The braking system remains securely engaged in the event of a moving vehicle colliding with the stopped vehicle. The braking system also remains securely engaged even if the foot of the operator is removed from the vehicle's brake pedal. The braking system is disengaged in response to the operator accelerating the vehicle, such as the operator's pressing of the vehicle's gas pedal, release of the vehicle's clutch and/or release of the vehicle's brake pedal. The rate of release of the braking system is responsive to the gas pedal position. The braking system is released rapidly in response to a substantially depressed gas pedal to facilitate a rapid start.

Abstract: A fluid control circuit (10) for operation of a brake comprises a first circuit part (11) including an actuator (12) having a chamber (13) and an operating part (14), the operating part (14) being movable to release or apply the brake when fluid under an operating pressure is fed to the chamber (13), an arrangement (17) to expel fluid from the chamber (13) when the operating pressure is released, thus to apply or release the brake, a second circuit part (18), a control valve (20) operable in a first condition to permit fluid to pass under the operating pressure to the chamber (13) of the actuator (12) in the first circuit (11) part and when in a second condition to permit fluid to pass from the first circuit part (11) into the second circuit part (18), the second circuit part (18) further comprising a buffer (23) to which fluid pressure is communicated from the first circuit part (11) when the control valve (20) is moved to its second condition, and a proportional fluid valve (30) to control the flow of fluid

Abstract: An anti-lock hydraulic brake system provides a phase of pressure increase, a phase of pressure decrease as well as a phase in which the pressure is kept constant. To this end, an outlet valve and a selector valve are provided. The selector valve is not connected to the pressure side of the pump as is usual but to the suction side of the pump. This arrangement produces the advantage that the selector valve is disposed in the low-pressure area of the brake system thereby eliminating the occurrence of great pressure surges which result in the emission of noise.

Abstract: A parking brake circuit for a hydraulically driven vehicle which prevents the occurrence of an erroneous operation at the time when the vehicle travels on a downward slope. The parking brake circuit comprises first and second main circuits (2, 3) for supplying hydraulic operating fluid into a hydaulically driven motor (1) for traveling the vehicle. A counterbalance valve (4) provided between these main circuits for feeding hydraulic operating fluid on the side of high hydraulic pressure into a pressure receiving chamber (6a) of a parking brake actuating actuator (6). A conduit (5) for connecting an outlet port of the counterbalance valve to the pressure receiving chamber, and a slow return valve (12) are provided in the conduit so as to control a flow of hydraulic operating fluid directed from the pressure receiving chamber to the counterbalance valve.

Abstract: A hydraulic parking brake controller for a motor vehicle for controlling the operation of a parking brake of the transmission output-shaft mounted type in response to the operating unit. The controller comprises a primary control and a secondary control. The primary control actuates and releases the parking brake at a first rate. The secondary control actuates the parking brake at a second rate slower than the first rate in an instance in which the parking brake is in the released state and the operation unit malfunctions. If a circuit break should occur in the operation unit while the parking brake is in the released state, the secondary control actuates the parking brake at the second rate. The parking brake is thus not actuated suddenly in the event of an abrupt wire disconnection, such that the braking action is dampened.

Abstract: A freight brake control valve device having an improved quick service function provided by suppressing premature cut off operation of the quick service limiting valve. In one embodiment of the invention, this is accomplished by connecting the quick service volume pressure to the underside of the quick service limiting valve piston during preliminary quick service to counteract the pressure pulse on the opposite side of the piston that occurs during the transition between the preliminary and secondary stages of quick service. In a second embodiment, pressure is created at the underside of the quick service limiting valve piston by dashpot action of the piston itself.

Abstract: In an hydraulic anti-skid braking system for a vehicle of the four wheel type in which an anti-skid modulator is adapted to control the brake on a rear wheel, an apportioning valve is incorporated in a line between each modulator and the brake, and a pressure-responsive control valve assembly is also incorporated in the line. The valve assembly comprises a pressure-responsive member, for example a piston working in a bore, and operable when subjected to a differential pressure in excess of a predetermined value, to restrict the effective area of passage through which fluid is dumped from the brake. This reduces the rate at which the pressure is released from the rear brake, thereby enabling this brake to do more work. Hence the stopping distance for the vehicle can be shortened.

Abstract: A snow brake control system in which application of the snow brake pressure during release of a normal brake application is withheld for a duration sufficient to assure movement of the vehicle brake apparatus from a brake application position to a release position, to thereby cause automatic slack adjuster action to take place. In one embodiment, operation of a piloted pneumatic valve is delayed by restricting the exhaust of pressure from a volume reservoir via a choke to thereby momentarily withhold the connection of snow brake control pressure to one inlet of a double check valve that is subject at its opposite inlet to normal brake control pressure. The double check valve is effective to connect the predominant one of the pressures at its opposite inlets to a relay valve to produce brake pressure. In a second embodiment, the double check valve is eliminated and the pilot pneumatic valve controls the connection of either snow brake or normal brake control pressure to the relay valve.

Abstract: A valve is used in a system employed on a vehicle for effecting the selected automatic disengagement of the transmission or main clutch upon the application of the vehicle service brakes, as well as the reengagement of the transmission when the brakes are released. Such valve allows rapid pressure buildup to the brakes, so that they may be rapidly applied, but delays the release of the brakes to allow ample time for reengagement of the transmission.