Table of Contents
What are the red and blue air lines?
On the back of the truck, on the driver side, there are 3 lines: red, green, and blue. The red line is the air line for the trailer’s emergency brake. The blue line is the air line for the trailer’s service brake. Connect these lines to the corresponding couplers and socket on the trailer before moving the trailer.
What is a service air line on a truck?
Service air line (normally blue): The service line (also called the control line or signal line) carries air which is controlled by the foot brake or the trailer hand brake. The pressure in the service line will similarly change depending on how hard you press the foot brake or hand valve.
What will happen if the air lines are crossed?
To keep the dirt and water out of the lines. What happens when you cross the air lines of an older trailer without spring brakes? You could drive away, but have no trailer brakes.
How do emergency air brakes work?
Air brakes use compressed air rather than hydraulic fluid. At idle, air pressure overcomes the diaphragm, resulting in a released brake system. When you depress the brake pedal, the air pressure decreases, turning the s-cam and spreading the brake shoes against the drum.
What does the red emergency supply line do?
The red line is the emergency or supply line and the reason it’s called the supply line is because it fills the air tank in the trailer and fills the air brake chambers releasing the spring brakes, and thus the parking brakes keeping them off when you’re going up and down the road.
What does Blue Air Line do?
As you can see in the picture above, the blue color hose, called service line, is used to carry air to the brakes. It is controlled by the foot brake on the trailer. The red one, called supply line or emergency line, is used to supply a steady stream of air to the air tanks.
What is the purpose of the service Air Line?
The Service Air Line controls the service brakes when you use the brake pedal. The Emergency Air Line supplies air to the trailer air tanks and the emergency brakes.
How does the air system work on a truck?
Air brakes work using compressed air instead of hydraulic fluid. The air compressor then pumps the air into the air storage tanks, which store the compressed air until it’s needed. Air pressure is used to apply the service brakes and release the parking brake. There are multiple air circuits in the system.
Which vehicles off track the most?
Longer vehicles will offtrack more. The rear wheels of the powered unit (truck or tractor) will offtrack some, and the rear wheels of the trailer will offtrack even more. If there is more than one trailer, the rear wheels of the last trailer will offtrack the most.
Why should you lock the tractor glad hands?
1. Why should you lock the tractor glad hands (or dummy couplers) to each other when you are not towing a trailer? A The connected brake circuit becomes a back up air tank.
What are air brakes on a truck?
An air brake or, more formally, a compressed air brake system, is a type of friction brake for vehicles in which compressed air pressing on a piston is used to apply the pressure to the brake pad or brake shoe needed to stop the vehicle.
What Colour are the airlines on a truck?
Modern trucks have two air lines which supply the trailer with air. The first is the supply air line (red) and the second is the service air line (yellow).
What is the emergency line on a combination car?
The service line is connected to relay valves. These valves allow the trailer brakes to be applied more quickly than would otherwise be possible. The emergency line (also called the supply line) has two purposes: (1) To supply air to the trailer air tanks, and (2) to control the emergency brakes on combination vehicles.
What’s the difference between emergency and service Air Lines?
Be sure you understand the difference between the Service Air Line and the Emergency Air Line. The Service Air Line controls the service brakes when you use the brake pedal. The Emergency Air Line supplies air to the trailer air tanks and the emergency brakes. What does the Service Air Line do?
What are the Air Lines and electrical lines on a trailer?
The red line is the air line for the trailer’s emergency brake. The green line is the electrical line. The blue line is the air line for the trailer’s service brake. Connect these lines to the corresponding couplers and socket on the trailer before moving the trailer. We recommend starting with the blue line since it is the farthest away.
Where are the air and electrical lines on a truck?
The electrical and air lines need to be connected and the landing gear needs to be raised all the way up. On the back of the truck, on the driver side, there are 3 lines: red, green, and blue. The red line is the air line for the trailer’s emergency brake. The green line is the electrical line.