Pneumatic antiskid braking system

Claim 1

A pneumatic antiskid braking system of the type wherein the variable volume motor chamber of a pneumatic brake actuator controlling the braking operation of at least one of the vehicle wheels is connected to a variable pneumatic braking pressure control source through an antiskid control valve means which are adapted, when actuated by an antiskid control unit in response to the skidding of said braked wheel, to terminate the connection between said control source and said motor chamber and thereafter to connect this latter to an exhaust conduit leading on the one hand to the variable volume exhaust chamber of said brake actuator opposite to said motor chamber and on the other hand to a relatively low fluid pressure reservoir (atmosphere) through a normally open shutoff valve operative to block fluid flow to said reservoir upon actuation of said antiskid control valve means by said antiskid control unit, characterized in that a normally closed exhaust valve, controlled by piston means, responsive to the pneumatic differential pressure between said opposed motor and exhaust chambers, is provided to directly connect said motor chamber to said low-pressure reservoir (atmosphere) when said pressure differential falls below a predetermined value.