The dual application valve is a manual valve activated by the brake pedal. The valve has two separate supply and delivery circuits for the front and rear service brakes. Separating the circuits allows the driver to gradually apply and release the brakes.

The supply, delivery and exhaust ports are identified by letters cast into the valve body next to the ports. The primary supply and delivery ports are located in the upper body portion and the secondary supply and delivery ports are located in the lower body portion of the valve. Both circuits serve as flow control valves. The flow of air directly relates to the travel of the brake pedal. The primary and secondary circuits use a common exhaust port protected by an exhaust diaphragm.