Abstract: A fluid pressure responsive valve includes a valve member mounted on a guide pin slidably carried by a piston. A valve guide is engaged by one side of the valve element, and the piston engages the opposite side. The piston controls the valve member. The valve guide acts as a stop for a check valve element that controls communication through the inlet port, and also guides and supports the spring controlling the check valve element.

Abstract: A fluid pressure braking system for a tractor-trailer combination vehicle includes a proportioning relay valve which controls communication to the rear wheel brakes of the tractor. When the tractor pulls a trailer, the proportioning control within the relay valve is disabled, but when the vehicle is operated in the "bobtail" mode without pulling a trailer a proportioned brake application is effected in which the braking pressure communicated to the rear brake actuator is a predetermined percentage of that in the front wheel braking circuit. The proportioning mechanism is also disabled when the front axle braking circuit malfunctions, so that upon loss of pressure of the front axle system, the driver effects a non-proportioned rear brake application.

Abstract: An electro-pneumatic braking system includes a tandem brake actuator including a service brake actuating section and an emergency/parking spring actuated section. Hold-off pressure is communicated to the emergency/parking section through a three-way solenoid valve from a pressure reservoir, and communication to the service actuator is controlled by an electro-pneumatic modulator. Service pressure is taken both from the branch of the conduit communicating with the air reservoir, and from the hold-off pressure in the emergency/parking reservoir. Accordingly, only a single line communicates fluid pressure from the reservoir to the brake, and service brake response time is improved because the hold-off pressure and the emergency/parking section of the actuator is used as a small reservoir immediately adjacent the service actuator.

Abstract: A proportioning control valve for heavy duty fluid pressure braking system includes a proportioning piston which is normally held in engagement with an abutment by control pressure. A tare pressure spring urges a caging member into engagement with a stop which is spaced a predetermined distance from the end of the proportioning piston, which is less than the distance between the valve engaging member carried by the proportioning piston in the proportioning valve member. Upon loss of pressure at the control pressure port, the proportioning piston is urged toward the caging member. The proportioning piston moves between the gap defined between the end of the proportioning piston and the caging member without opposition from the tare pressure spring, thereby permitting the full force of fluid pressure to break seal friction between the seals carried by the proportioning piston and the wall of the housing.

Abstract: A rotor for a disc brake assembly is provided with a first portion (52) adapted for attachment to a wheel assembly (28), a second portion (54) engageable with at least a pair of friction elements and a connecting portion (56) extending between the first and second portions. The second portion (54) defines an inboard surface (60) and an outboard surface (64) facing the first portion (52). The connecting portion (56) cooperates with the second portion (54) to define a heat sink (78) at the radially inner edge of the inboard surface (60) to substantially offset tilting of the second portion toward the first portion in response to temperature expansion of the rotor second portion (54).

Abstract: An adaptive braking system for a vehicle having fluid pressure actuated brakes. The system includes a wheel speed sensor which generates a speed signal proportional to the rotational velocity of a vehicle wheel, and an incipient skid detecting circuit which is responsive to the speed signal to generate a skid detecting signal when an incipient skidding condition of the vehicle wheel is sensed. A modifying circuit is responsive to the output of the skid detection circuit, and generates a signal relieving the fluid pressure in the vehicle brakes when the skid detection circuit senses an incipient skidding condition. Upon termination of the incipient skidding condition, the modifying circuit causes the brake pressure communicated to the vehicle's brakes to be increased at a rate lesss than the maximum rate at which the braking pressure in the system is capable of increasing, to thereby provide a "slow build" cycle until another incipient skidding condition is sensed.

Abstract: An adaptive braking system for a vehicle having fluid-pressure operated brakes which includes a skid detecting circuit and a signal modifying circuit. The signal modifying circuit responds to the output of the skid detecting circuit to drive a duty cycle translator to generate a control signal which controls actuation of a modulating relay valve adapted to control fluid communication to the brake actuators. The duty cycle translator includes a pseudo-pressure-feedback control circuit which generates a signal approximating the response characteristics of the modulating relay valve and the brake actuators. The pseudo-pressure-feedback control enhances response of the system without requiring a pressure transducer to be used in the modulator or brake actuators to sense a feedback pressure.