What is the function of a tractor protection valve?
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 PSI should the tractor protection valve?
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 …
How is the tractor protection valve operation?
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). When the pressure in the supply line reaches 45 psi, the service line port of the tractor protection valve opens.
When should the tractor protection valve pop out?
Explanation In vehicles equipped with an automatic tractor protection valve, the valve will pop out if air pressure drops to a level between 20 and 45 psi. When the valve pops out, the protection valve will close, stopping the flow of air.
How can you manually check the slack adjusters?
With service brakes in the released position, mark the push rod even with the brake chamber. Make a full brake application and mark the push rod again. Measure between the two marks to determine the length of push-rod travel (stroke).
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.
When the emergency line loses pressure what happens to the tractor protection valve?
When the emergency line loses pressure, it also causes the tractor protection valve to close (the air supply knob will pop out). Emergency lines are often coded with the color red (red hose, red couplers, or other parts) to keep from getting them mixed up with the blue service line.
How do you test low air pressure warning signal?
The best way to test the low air pressure warning signal is to turn off the engine while leaving the electrical power on. Then step on and off the brake pedal. The low air pressure warning signal should come on when the pressure falls below 60 psi. You should never need to get down to 30 psi.
Which valves are the tractor protection system?
The trailer-supply valve and tractor protection valve make up the tractor protection system. This system prevents air loss from the tractor when not hooked to a trailer or if a trailer breaks away.
When you test the tractor protection valve The Red air supply control knob should go into the
When you test the tractor protection valve, the red air supply control knob should go into the ________ position. EXPLANATION: -45 psi, the trailer air supply control knob should pop out, or the valve control should go from the “normal” to the “emergency” position.
When checking the trailer emergency brakes the tractor protection valve should be placed in the what position?
Charge the trailer air brake system and check that the trailer rolls freely. Then stop and pull out the trailer air supply control (also called tractor protection valve control or trailer emergency valve), or place it in the “emergency” position.
At what PSI will the tractor protection valve control knob pop out when performing the air pump down test?
The tractor protection valve and parking brake valve should close (pop out) on a tractor-trailer combination vehicle and the parking brake valve should close (pop out) on other combination and single vehicle types when the air pressure falls to the manufacturer’s specification (20 – 40 psi).
Why do brakes fade?
Brake fade happens when the braking system components no longer generate the friction needed to stop your car in an appropriate amount of time or distance. To stop the car, you have to press the brake pedal farther down and for longer than before.
What are service brakes on a semi?
The service brake system applies and releases the brakes when one uses the brake pedal during normal driving. The parking brake system applies and releases the parking brakes when one uses the parking brake control.