
Trailer Air Supply Valve
The valve is an octagon-shaped red button on the dashboard. Supplies air to the trailer reservoirs, and by doing so controls the application and release of the trailer’s spring brakes. If you forget how the button works you can always read what’s written...
Tractor Protection Valve
The tractor protection valve protect the tractors air supply from being depleted in the event of a trailer breakaway. Any truck or tractor designed to pull a trailer fitted with air brakes will be equipped with a tractor protection system. The tractor protection...
Tractor Parking Brake Control Valve
Applies and releases the truck or bus’ parking brakes and is found on the vehicle’s dash. It is a yellow 4-sided button on the dashboard. If your vehicle has a air brake equipped trailer attached, the tractor parking brake will also cause the trailer...Spring Brake Modulator (Inversion) Valve
OBSOLETE Used on some vehicles with dual air systems. This device provides a means of using the force of the spring brakes to assist in stopping a vehicle in an event of a failure in the rear (primary) air system.