Fluid pressure braking system with parking brake-service brake interlock
AssigneeThe Bendix Corporation
InventorRichard C. Fannin
Life of this patent
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Abstract
A vehicle fluid pressure braking system is disclosed which includes brake-applying devices having separate service and parking actuators. Separate service and parking actuation circuits are provided to control actuation of the service and parking actuators, respectively. An interlocking valve is provided which prevents release of the parking actuator until a predetermined fluid pressure level is communicated to the service actuator. This interlocking valve prevents inadvertent release of the parking actuators, and also prevents release of the parking actuators in a situation in which a malfunction of the service braking circuit would render operation of the vehicle dangerous.
Claims15
In a vehicle fluid pressure braking system having a service braking circuit and a parking braking circuit, a brake actuator having service braking means connected in said service braking circuit and communicated to a fluid pressure source when a service brake application is effected, said brake actuator including parking means connected in said parking braking circuit for holding said actuator in a brake-applied condition when a parking application is effected, an operator-actuated control valve for controlling communication in said service braking circuit, and actuable to communicate fluid pressure to said service braking means, and interlock valve means responsive to actuation of said control valve to prevent release of said parking means until said control valve is actuated to communicate a predetermined pressure level to said service braking means, said interlock valve means including means responsive to the fluid pressure level in the parking circuit to maintain release of said parking means after the control valve is released until the fluid pressure level in the parking braking circuit drops below a predetermined level.
In a vehicle fluid pressure braking system having a service braking circuit and a parking braking circuit, a brake actuator having service braking means connected in said service braking circuit and communicated to a fluid pressure source when a service brake application is effected, said brake actuator including parking means connected in said parking braking circuit for holding said actuator in a brake-applied condition when a parking application is effected, and interlock valve means responsive to the fluid pressure level communicated to said service braking means to prevent release of said parking means until a predetermined pressure level is communicated to said service braking means, said interlock valve means including a vent port, an inlet port connected in said parking circuit, an outlet port connected to said parking means, and a control port adapted for communication in said service braking circuit, said valve means being responsive to the pressure level at said control port to shift from a first condition preventing communication between said inlet and outlet ports and communicating said outlet port to said vent port to a second condition communicating the inlet to the outlet and closing said vent port when the pressure level at said control port exceeds a predetermined value, pressure differential responsive valve means connected to said control port, said pressure differential responsive valve means comparing the pressure level at said outlet port with the pressure level in said service braking circuit and communicating the greater of said pressure levels to said control port.
Dependencies are inferred from the claim text.