Abstract: The manual valve normally attached to the wet tank of an air pressure system in a motor vehicle which accumulates moisture is replaced by an automatic valve which has an inlet port connected to the drain line from the wet tank and an outlet port vented to the atmosphere. This valve is operable between an open position where the inlet and outlet ports are interconnected and a closed position where these two ports are isolated from each other. An air line which is used to activate the valve is interconnected to the parking brake of the motor vehicle and is operable to move the valving means to the closed position during normal operation of the vehicle and to the open position whenever the parking brake is engaged to thereby automatically drain moisture from the wet tank while the vehicle is parked.

Abstract: Valving apparatus for use in automotive vehicles which employ an air pressure system utilizing an air pressure tank, a wet tank interconnected to the air pressure tank for accumulating moisture and a manual valving system for draining moisutre from the wet tank. The manual valve is replaced by an automatic valve which has an inlet port connected to the drain line from the wet tank and an outlet port vented to atmosphere and operable between open and closed positions. The valve actuation means is interconnected to the electrical system of the vehicle and also to the pressure system of the vehicle and is operable to move the valving means to a closed position during operation of the vehicle and to an open position during vehicle shut down to automatically drain moisture from the wet tank while the vehicle is idle.