When the pressure in the supply line reaches 45 psi, the service line port of the tractor protection valve opens. … This allows application air pressure to travel down the service line to the trailer when a brake application is made.
How do you test a tractor protection valve?
You should test the tractor protection valve by allowing the air supply to properly charge, turning off the engine, then releasing air from the system by pressing the brake pedal several times. The tractor protection valve should move into its emergency position when psi drops to an unsafe level.
What is the function of a tractor protection valve?
Application: Tractor protection valves are commonly mounted at the rear of the cab. The purpose of the Tractor Protection valve is to protect the tractor air brake system in the event of a trailer breakaway or severe air leak. They are also used to shut off air to the trailer before disconnecting the lines.
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.)
When the tractor protection valve is opened it allows air to?
When the pressure in the supply line reaches 45 psi, the service line port of the tractor protection valve opens. This allows application air pressure to travel down the service line to the trailer when a brake application is made.
At what pressure must the tractor protection valve operate to pass inspection?
Title 49, Section 393.43, which addresses breakaway and emergency braking, establishes an “explicit requirement that the tractor protection valve or similar device operate when the air pressure –both primary and secondary reservoirs – on the towing vehicle is between [20 and 45 psi].” The regulation is intended to …
What color is tractor protection valve?
The other is the tractor protection valve (TPV), located on the towing vehicle’s frame or body. The TPV is also called a ‘towing vehicle’ protection valve. The TSV has a red colored, eight-sided knob and is controlled by the driver.
What does the blue service line do?
The blue line is the air line for the trailer’s service brake.
When testing the tractor protection system the 2 main components you are testing are?
1) the first one is to pump down the air pressure in the system between 20 and 45psi (pounds per square inch) the trailer air supply will pop out, shutting air off to the trailer. 2) the second test is to go out to the trailer to ensure that the parking brakes have indeed applied.
When hooking a tractor to a trailer you will know the trailer is at the correct height when the?
The trailer is at the right height when: It will be raised slightly when the tractor is backed under it. Which part of the kingpin should the locking jaws close around?
Why should you lock the tractor glad hands to each other?
1. Why should you lock the tractor glad hands (or dummy couplers) to each other when you are not towing a trailer? A The connected brake circuit becomes a back up air tank.
Why do many trailers built before 1975 have no parking brakes?
You could drive away, but have no trailer brakes. Why do many trailers built before 1975 have no parking brakes? They don’t have spring brakes. If the service air line comes apart while driving but the emergency line is okay, what happens immediately?