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 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.
How does a pressure protection valve work?
This serves to allow a build up of air pressure in the system before it is allowed to become available to an accessory such as an air suspension. … When the pressure on the supply side falls the valve closes to preserve some amount of air pressure on the delivery side of the valve.
How does a multi circuit protection valve work?
The Multi-Circuit Protection Valve takes compressed air from the air supply system comprising the air compressor and air treatment devices (contaminant removal and pressure control) then distributes the compressed air to the system reservoirs.
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 color is the service line on a tractor trailer?
In most cases, the trailer couplers are colour-coded during manufacturing – red for the supply line and blue for the service line (See Diagram 5-2). By matching these colours, the lines are properly connected.
At what pressure must the tractor protection valve operate to pass inspection?
Between approximately 20-40 PSI on a tractor-trailer combination vehicle, the tractor protection valve and parking brake valve should close (pop out). On other combination vehicle types and single vehicle types, the parking brake valve should close (pop out).
When should you drain your air tanks?
Each air tank is equipped with a drain valve in the bottom. There are two types: Manually operated by turning a quarter turn or by pulling a cable. You must drain the tanks yourself at the end of each day of driving.
What is a pressure protection valve?
Pressure protection valves are used to isolate auxiliary air systems from the brake system. This is done to preserve air for braking in the event that the auxiliary system develops a major leak.
What is the normal operating range for an air brake system?
Normal air brake system pressure range is around 690 to 828 kPa (100 to 120 psi). Drivers should know the normal pressure range of the vehicle they operate and should report any abnormal condition.
When the tractor protection valve is opened it allows air to?
When the pressure in the supply line reaches 45 psi, the service line port of the tractor protection valve opens. This allows application air pressure to travel down the service line to the trailer when a brake application is made.
What does a quick release valve do?
The function of a quick-release valve (Fig. 23) is to rapidly exhaust air from the controlled device. It is normally located adjacent to the controlled device, rather than requiring exhaust air to return and exhaust through the control valve.