The safety valve protects air tanks and the rest of an air brake system from accumulating too much air pressure. The safety valve is usually set to open at 150 psi.

If you have an Anti-Lock Braking System (ABS) equipped on only the tractor, only the trailer, or only one axle, you will still have more control over the vehicle when braking than you would without ABS. You should brake normally.

In an air brake system, air tank drains are used to remove water and compressor oil from the air tanks. When operating a drain, be sure to drain the tank completely.

The purpose of an Anti-Lock Braking System (ABS) is to prevent wheel lockup while brakes are being applied.

Pressing and releasing the brake pedal unnecessarily can let air out of the braking system faster than the compressor can replace it. Air brakes may cease to work effectively if the pressure becomes too low.

While driving downhill, you should hold down the brake pedal until your vehicle reaches a speed 5 mph below your safe speed, then release the brake pedal. Repeat this process.

All trucks, truck tractors, and buses must be equipped with emergency brakes and parking brakes.

Compressed air in an air brake system usually contains a certain amount of water and compressor oil. The water and oil can damage the brakes if left to accumulate in the system. Tanks must be drained regularly to remove this build-up.

Some older vehicles have front brake limiting valves with "normal" and "slippery" settings. Setting a brake limiting valve to "slippery" reduces the vehicle's stopping power, so a driver should make sure the valve is in its "normal" position. Front wheel braking has proven to be effective in all driving conditions.

A dual air brake system is made up of two separate air brake systems. The systems share a single set of brake controls, but each has its own air tanks, hoses, and lines. One system typically operates the regular brakes on the rear axle or axles while the other system operates the regular brakes on the front axle.

While driving, spring brakes are generally held in place by air pressure. If the air pressure gets low enough, the springs will activate the brakes.

Vehicles with ABS have yellow malfunction lamps to alert drivers when the braking systems are not working. Be sure you know where the malfunction lamp on your vehicle is before beginning a trip.

If the low pressure warning signal activates while you are driving, it is important that you safely exit the roadway as soon as possible and park your vehicle. If the air pressure gets too low, the brakes will no longer work well enough for you to stop safely.

It is important to know the maximum air loss rate that is safe for your specific vehicle. A single vehicle with air brakes should have a leakage rate no higher than 3 psi in a minute during an applied leakage test.

Before driving a vehicle with a dual air brake system, allow time for the air compressor to build up a minimum of 100 psi pressure in both the primary and secondary systems. Watch the air pressure gauges to monitor the pressure levels.

The brakes in an air brake system use compressed air to function properly.

A vehicle with air brakes must be equipped with a low air pressure warning signal. If the warning signal goes off while a vehicle is being driven, the driver should bring the vehicle to a complete stop and have the system repaired.

Anti-Lock Braking System (ABS) malfunction lamps are usually yellow. Even if the ABS isn't working properly, a driver will still have access to the vehicle's usual braking functions.

Do not use the brake pedal when the spring brakes are on. This could damage the brakes by subjecting them to the combined forces of springs and air pressure.

If brakes are overused, they can become too hot. This overheating causes them to fade, making them less effective at slowing the vehicle.

In an air brake system, the air compressor pumps air into the air storage tanks. The air compressor is controlled by the air compressor governor.

Air brakes function through the use of compressed air.

An Anti-Lock Braking System (ABS) helps to provide additional control during hard braking, but does not necessarily shorten a vehicle's stopping distance.

If your vehicle has air brakes, the air compressor drive belt should be checked before each drive. Check the tightness of the belt and verify that it is in good condition.

When a brake pedal is pressed and the S-cam is turned, the S-cam presses the brake shoes against the inside of the brake drum. This causes friction and will cause the vehicle to slow.