Prevents a trailer from being accidentally released. A tractor protection valve keeps air in a tractor or truck air brake system should the trailer break away or develop a bad leak. The valve will close automatically if the pressure drops to an unsafe level.
What happens when the tractor protection valve closes?
When the tractor protection valve closes, it stops any air from going out of the tractor. It also lets the air out of the trailer emergency line. This causes the trailer emergency brakes to come on, with possible loss of control. (Emergency brakes are covered later.)
What is another name for the tractor protection valve?
Any truck designed to pull a trailer with air brakes is going to be equipped with tractor protection system, which consists of the tractor protection valve–just to confuse you [CHCUCKLING] the system and the valve are called the same thing – the tractor protection valve and the red, eight-sided trailer air supply …
Where are the shut off valves on a tractor trailer?
These valves permit closing the air lines off when another trailer is not being towed. You must check that all shut-off valves are in the open position except the ones at the back of the last trailer, which must be closed.
How is the tractor protection valve operation?
A tractor protection valve (Fig. 38) is usually mounted on the cab or chassis of the tractor. When the trailer-supply valve is open, air passes through the bottom of the tractor protection valve and charges the trailer through the supply line (also called the emergency line).
Which shutoff valves should be open and closed?
All shut-off valves should be open. … When starting a trip, be sure that all shut-off valves are in the open position, except for the last valves on the rear trailer. It is important that air reaches the brakes on all trailers and that the air is not able to escape from the back of the vehicle.
What is the blue air brake button for?
The yellow one controls brakes on all axles, the red is only for trailer, and the blue is only for the truck unit.