Readers ask: What Is The Little Valve On The Red Supply Line Of A Tractor And Trailer For?

What is a tractor trailer 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 color is the tractor protection valve?

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. The driver opens (pushes in) the TSV when a trailer is being towed and closes it (pulls out) when there is no trailer present.

Where are the shut off valves on a tractor trailer?

Shut – off Valves 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.

Where is the trailer hand valve located?

Subsequently, one may also ask, where is the trailer hand valve? Often, a hand valve is also fitted on the steering column or the instrument panel of the towing vehicle so the driver can apply the trailer service brakes independent of the towing vehicle’s brakes.

What color is the supply line on a tractor trailer?

Generally these lines are color coded where the service line is blue and the supply line is red. If the trailer connectors are not color coded, then both are usually black or silver and the emergency line will connect to the receptacle closest to the driver’s side on the front of the trailer.

What gear should the tractor engine be in after you have uncoupled?

15. You want to inspect the trailer support. You should place the tractor transmission in which gear after you have uncoupled the trailer? Neutral.

What is the maximum air loss rate for a tractor and trailer?

Air loss rate should be less than 3 psi in 1 minute for a single vehicle. Air loss rate should be less than 4 psi in 1 minute for combination vehicles (vehicles with a trailer ).

How do you test a tractor protection valve?

To test the tractor protection valve, the trailer supply valve must be closed (pulled out), the trailer service line must be disconnected, and the service brakes applied. No air should be exhausting from the trailer service line. If air exhausts from the service line, the tractor protection valve is defective.

Which shutoff valve is open and closed?

All shut – off valves should be in the open position, except the rear shut – off valves. 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.

Where are the shut-off valves?

Locating the proper valve Basements – the shut – off valve is typically located near the front foundation wall. The main water may come through the concrete floor or through the wall. The valve is typically within three to five feet of where the main water enters.

What might happen if the trailer is too high?

What might happen if the trailer is too high when you try to couple? If the trailer is too low, the tractor may stike and damage the trailer nose; if the trailer is too high, it may not couple correctly. If there is space something is wrong and the trailer would come loose very easily.

When should you use the hand valve?

The trailer hand valve, also called the trolley valve or Johnson bar, is used to work the trailer brakes. It should be used only to test the brakes. Using it while a vehicle is in motion could cause a skid.

When should a trailer hand valve be used?

The trailer hand valve should be used only to test the trailer brakes. Do not use it in driving because of the danger of making the trailer skid. The foot brake sends air to all the brakes on the vehicle (including the trailer (s). There is much less danger of causing a skid or jackknife when using just the foot brake.