Pressure holding valve
AssigneeWagner Electric Corporation
InventorJohn M. Ury
Life of this patent
Estimating the term…
Abstract
A pneumatic vehicle spring parking brake pressure holding valve abruptly seals an atmospheric outlet and enables the valving of brake release air pressure to the spring parking brakes when the vehicle reservoir attains a first pressure. Parking brake release is thus enabled. In the case of loss of air pressure from the system, the pressure holding valve retains the brakes fully released until the vehicle reservoir air pressure drops to a second pressure which is lower than the first. The pressure holding valve thereupon abruptly opens its atmospheric outlet thereby rapidly exhausting the air pressure in the spring parking brakes and setting them.
Claims6
A pressure holding valve suitable to effect the application and removal of release air pressure to spring-actuated parking brakes comprising:
- a. means for blocking the entry of air pressure into said pressure holding valve until a first predetermined input air pressure is attained;
- b. an exhaust valve in said pressure holding valve for admitting atmospheric air pressure to said parking brakes;
- c. means for closing said exhaust valve when said first predetermined air pressure is attained;
- d. means for connecting said input air pressure to said parking brakes;
- e. means for holding the air pressure in said parking brakes substantially equal to the highest input air pressure attained after said first predetermined air pressure is once exceeded and until the input air pressure decreases to a second predetermined level;
- f. said second predetermined air pressure being lower than said first predetermined air pressure;
- and
- g. means for fully opening said exhaust valve when said second predetermined air pressure is attained whereby the brake air pressure is fully exhausted.
Dependencies are inferred from the claim text.