That valve should be adequate to release the spring brakes, but it will not work with the service brake section of the spring brake pot. The two output lines should be plumbed to the "Park" lines of the spring brake chambers, with direct system pressure plumbed to the input line of the valve. The pilot valve line needs to be plumbed to the in-cab parking brake release valve. Air pressure from the pilot line opens the relay valve and sends full air pressure to the spring brake release. If pressure drops at the relay port, due to pulling the park valve out or loss of system pressure, the spring brakes apply.
You'll need another valve from the foot pedal to modulate pressure to the service brakes for stopping. That system uses a different type of relay valve, not a simple on/off type.
Jerry
