What is a Tractor Protection Valve?

The Tractor Protection Valve is an important part of the air brake system and it helps to prevent a total loss of air from the tractor in case the trailer breaks away or the connection lines between them gets separated or ruptured. The engineers named this system because it works to protect the truck’s air supply against catastrophic air losses that can occur when, for example, a semi-trailer falls off the back of a truck.

The TPS has been designed to detect any sudden drops in pressure so that drivers are alerted right away if there is a problem with their brakes. It also has safeguards built into it such as secondary pressure valves which help maintain optimal pressure levels even when one side experiences an unexpected drop. This ensures that tractors remain safely attached and able to stop quickly and efficiently should any emergency arise on the road.

Tractor Protection System

tractor protection system
tractor protection system

The Tractor Protection System consists of two valves: the Trailer Air Supply Valve and the Tractor Protection Valve. Both of these valves are integral components of the tractor protection system, working together to protect it from any potential damage or malfunctioning. The Trailer Air Supply Valve regulates the amount of air supplied to the trailer while the Tractor Protection Valve monitors and protects against any irregularities in performance. This system ensures that both tractors and trailers are safe and well-maintained at all times.

Tractor Protection Valve

tractor protection valve
tractor protection valve

When the tractor protection valve detects catastrophic air loss from the trailer, it functions as a “panic button” which shuts off air supply to the trailer when system pressure drops between 20psi (138kPa) and 45psi (310kPa). This helps protect against any potential danger by stopping airflow before it has time to cause any damage.

The tractor protection valve is designed to safeguard the air brake system of a tractor in the event of trailer breakaway and extreme leakage in either the tractor or trailer. It prevents further damage, allowing for safe operation and compliance with all applicable safety regulations. The valve provides an important level of protection for both drivers and cargo by ensuring that brakes can still be applied as needed, even under difficult circumstances.

The Tractor Protection System is an important safety system that provides protection to both the tractor and trailer in emergency braking situations. This system includes remotely controlled cutout valves, which are installed on the service and emergency lines of the tractor and trailer. When the control valve is in its normal position, it allows for normal service and emergency braking functions for both components.

In case of a severe air loss or any other condition which may require an emergency application of the trailer brakes, operators can move the control valve lever to its Emergency position, whereupon both service and emergency brake lines will be closed off at the tractor protection valve. This provides a convenient daily check of all relay valves on trailers where tractors aren’t present. The Tractor Protection System ensures maximum safety against unexpected issues during operation with minimal effort required from operators for regular maintenance checks.

Importance of Tractor Protection Valve

importance of tractor protection valve
importance of tractor protection valve

The trailer air supply valve must shut off air to the trailer between 20psi (138kPa) and 45psi (310kPa).

With the truck (parking brake) and trailer (air supply) spring parking brake buttons pushed in on the instrument panel, it is necessary to pump the brake pedal to reduce the system air pressure.

When the system air pressure is between 20psi (138kPa) and 45psi (310kPa), the trailer air supply valve should pop automatically, shutting off air to the trailer.

The operator must move the control to the EMERGENCY position whenever a trailer is disconnected, or when operating a tractor without one if cut-off valves are not installed in the trailer connections on the tractor. It is important to note that using the tractor protection valve as a parking brake should be avoided, as it was not designed for this purpose.

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1 thought on “What is a Tractor Protection Valve?”

  1. I have been in the trucking industry for a long time and I’ve seen firsthand the importance of the Tractor Protection System. It ensures that the tractor and trailer remain securely attached while allowing for quick and efficient braking when needed. On more than one occasion, I have seen the Tractor Protection Valve come to the rescue and prevent a major accident from occurring. It’s an incredibly valuable system and one that I believe all truckers should be aware of and be familiar with.


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