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).
Where is a tractor protection valve located?
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.
Which valves are the tractor protection system?
The tractor protection system consists of 2 valves. One is the trailer supply valve (TSV), a push/pull valve located on the instrument panel. 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.
What controls the tractor protection valve?
When it comes to the red button, however – the trailer supply valve that controls the tractor protection control valve – there is an FMCSA regulation covering trip pressure.
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.
What does a Gladhand do?
This term refers to the coupling device used to connect the service and supply lines of the trailer to the truck or tractor. These couplers have a snap-lock position and a rubber seal that prevents air from escaping.
What is 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.
What does pressure protection valve do?
Protects the air brake system in the event of a leak or failure within the air suspension system.
When the emergency line loses pressure what happens to the tractor protection valve?
The tractor protection valve will close automatically if air pressure is low (in the range of 20 to 45 psi). 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.
What are three functions of the relay emergency valve?
The relay emergency valve serves three main functions in the system:
- It relays air from the trailer reservoir -> trailer brake chambers during a brake application. …
- It directs trailer reservoir air -> trailer brakes, causing an emergency application of the brakes.
When you test the tractor protection valve The Red air supply control knob should go into the
The trailer air supply control – or tractor protection valve control – should pop out – or go from “normal” to “emergency” position when the air pressure falls into the pressure range specified by the manufacturer. – usually within the range of 20-45 psi.
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).
Where are the shut off valves on a tractor trailer?
Shut-off valves (also called “cut-out cocks”) are used in the service and supply air lines at the back of trailers used to tow other trailers. These valves permit closing the air lines off when another trailer is not being towed.