The valve is an octagon-shaped red button on the dashboard.
The tractor protection valve protect the tractors air supply from being depleted in the event of a trailer breakaway.
Must be used whenever two sources of air are used to operate a single device or system.
For CDL air brake test, the driver must know there are 2 in the system.
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.
Several relay valve throughout the air brake system reduce brake lag, thus allowing the brakes to apply faster.
OBSOLETE |
Fills the trailer air tanks (reservoir) and applies and releases the trailer service brakes. The relay emergency valve also applies the trailer emergency brakes in the event of a trailer breakaway or normal disconnect.
Knowledge Test Question: In the event of a trailer break away, the relay emergency valve is required to apply the trailer service brakes for a minimum of 15 minutes.
The quick release valve moves to reduce brake lag in the air brake system.