Quick Answer: What is 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.

How does a tractor protection valve work?

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). … This allows application air pressure to travel down the service line to the trailer when a brake application is made.

What happens when a tractor protection valve fails?

When the valve fails to close before pressure drops below 20 psi (138 kPa), the power unit is defective. This vehicle has a violation* that is an OOS condition. 5. When the gladhand couplings are disconnected, the trailer emergency (spring) brakes must also apply automatically.

What is the main purpose of the 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.

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What are the five basic components of an air brake system?

5 Basic Components of an Air Brake System in Trucks

  • Air compressor.
  • Reservoirs.
  • Foot valve.
  • Brake chambers.
  • Brake shoes and drums.

How fast should a truck build air pressure?

Air pressure build-up from 85 psi to 100 psi should take 45 seconds or less. While driving, observe the air pressure gauge during build-up to ensure proper air system operation. braking, pull over at a safe place and perform the 2 minute / 5 psi leakage test.

Which shutoff valves should be open and closed?

If you’re only pulling one trailer, the shut off valves should always be closed or else the air will simply escape out the back of the trailer. If you’re pulling more than one trailer, all valves should be open except the very last trailer, which should have all valves in the closed position.

What is the emergency air line for?

Emergency air line:

The emergency line (also called the supply line) has two purposes: (1) To supply air to the trailer air tanks, and (2) to control the emergency brakes on combination vehicles. Loss of air pressure in the emergency line causes the trailer emergency brakes to come on.

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 …

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When the emergency line loses pressure what happens to the tractor protection valve?

D. The suspension springs to extend. The tractor protection valve keeps air in the trailer’s braking system should the trailer break away or develop a leak. A loss of air pressure in the emergency line will cause the tractor protection valve to open and the emergency trailer brakes to activate.