What is a treadle assembly?
In many vehicles, the brake valve and treadle (pedal) assembly is mounted to the cab floor where it is subject to abrasive dirt and sand, as well as corrosive chemicals such as road salt and water. As a result, a small amount of corrosion in the metal parts of the assembly is normal (such as light rust or oxidization).
What is the purpose of a treadle valve?
The treadle valve is shown in Figure 2-6. Its function is to regulate the air pressure in the service line (blue line) that controls how forcefully each brake is applied.
What is a foot valve on a truck?
When you step on the brake pedal, this is the valve that starts the brake application. The foot valve can be mounted under the floor of the cab or inside the firewall.
How does a relay valve work?
In a truck’s air brake system, relay valves get a signal when a driver presses the treadle, which then opens the valve and allows air to enter the brake chamber via air inlet. The diaphragm gets pushed, then the rod, then the slack adjuster which twists to turn the brake camshaft.
What is a brake valve?
The driver’s brake valve is a complicated valve system for controlling the compressed air brake of a railway vehicle. In the simplest case the position of the lever controls the extent to which the valve opens, how quickly compressed air can be released from the pipes or the reservoir in the braking system.
What is the first thing you should do when a low air pressure warning comes on?
The first thing to do when a low air pressure warning comes on is: Stop and safely park as soon as possible.
What is an air Governor?
The governor (Fig. 20), which is usually compressor mounted, operates in conjunction with the compressor and maintains reservoir air pressure between a predetermined maximum and minimum pressure.
What is brake foot valve?
In this system, brake lag is minimized. Release of the foot valve stops the flow of application air. The relay portions of the valves return to their original positions, stopping the flow of air pressure. The exhaust ports of the valves exhaust air pressure from the brake chambers, releasing the brakes.
Where is relay valve located?
Applying the brake sends signals to the relay valve in a vehicle. The relay valve is hooked to the brake pedal and the rear brakes through various series of wires, which are wired through a central control unit in newer vehicles. It can usually be found on the frame underneath the vehicle next to the air tank.
What is a SR 1 valve?
The function of the SR-1 valve is to supply a specific, limited hold-off pressure to the spring brakes, and in the event of loss of No. 1 service air pressure, to modulate the spring brakes through the use of the service brake valve. The SR-1 valve must be mounted with the exhaust port down toward the road surface.