Air Line color
Every tank has a label, and every control port has a small sticker as well. European truck manufacturers usually install black tubes, which are sometimes numbered; however, some trucks have a slightly different air line routine, but the aniway air line system meets DOT and ECE requirements.
What color is the emergency line on a tractor trailer?
The tractor protection valve closes when the emergency line loses pressure (the air supply knob pops out). Emergency lines are often coded with the color red (red hose, red couplers, or other parts) to avoid being mixed up with the blue service line.
What is the service line on a tractor trailer?
The emergency line, which is usually smaller and blue or has blue fittings, provides air pressure to fill the semi-trailer’s reservoir tank and the pistons that activate the brakes. The service line, which is usually smaller and blue or has blue fittings, is pressurized by pressing the brake pedal during normal braking.
What color is the service line on a semi?
The trailer couplers are usually color-coded during manufacturing, with red for the supply line and blue for the service line (see Diagram 5-2), and the lines are connected properly by matching these colors.
What Colour is the service line on a tractor unit?
Connect the service airline ( yellow ) and electrical connections. Connect the emergency airline ( red ) and watch for any unexpected movement. Apply the tractor unit parking brake, stop the engine, and remove the keys.
What color is the tractor brake?
The yellow one controls all axle brakes, the red one only controls trailer brakes, and the blue one only controls the truck unit.
Where are the shut off valves on a tractor trailer?
Shut-off Valves These valves allow you to shut off the air lines when another trailer isn’t being towed; make sure all shut-off valves are open, except those at the back of the last trailer, which must be closed.
What is another name for the service line?
The foot brake or trailer hand brake controls the service line, also known as the control line or signal line, which transports air to the trailer brakes.
What are spring brakes on a tractor trailer?
Spring brakes are commonly used as parking brakes and can be found on the rear axle of heavy trucks. They work as follows: pressure is applied to the spring side, which allows the parking brake to disengage, and parking brakes are applied when the spring is decompressed (at 20 lbs).
Are air brakes better than hydraulic?
Air brakes are a lot easier to connect than hydraulic brakes, and using air instead of hydraulic fluid prevents a lot of potential problems. For example, minor leaks in the brake lines won’t cause the system to fail completely, and air brakes can even work with major leaks.
What will happen if the trailer supply line is disconnected from the truck?
If the brake application is held long enough to cause enough loss of pressure in the tractor system, the service line will rupture, causing the tractor protection system to close off, exhausting the supply line to the trailer.
When you get ready to back under the semi trailer you should line up?
4. When you’re ready to back under the semi trailer, line up as follows: A About 12 degrees off the trailer’s line.
What will happen if the air lines are crossed when you hook up to an old trailer?
What happens if the air lines are crossed when you hook up to an old trailer? If the trailer does not have spring brakes, you can drive away but you will not have trailer brakes.
What are Suzie lines?
When coupling/uncoupling to a (semi) trailer, the ‘Suzies’ air lines are found at the rear of the tractor unit. There are usually two air lines: red for the emergency line and yellow for the service lines, which provide compressed air from the tractor unit to the trailer brakes.
What is the yellow air line on a lorry?
The supply air line (red) and the service air line (yellow) are the two air lines that supply the trailer with air in modern trucks.