Michigan CDL DMV Air Brakes 2

On long and/or steep downgrades, you should primarily use engine braking to control the speed of your vehicle. Use your brakes only as a supplement to this effect.

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.

In a vehicle with dual parking control valves, there is a separate air tank that can be used to temporarily release the spring brakes if they have been activated due to low air pressure. Pushing in the proper control will release the spring brakes for a short period of time, allowing the driver to move the vehicle in an emergency.

When pressing the brake pedal in a vehicle with S-cam brakes, air will enter the brake chambers. The added air pressure will push out the rods and move slack adjusters, twisting the brake camshafts.

It is important to know the maximum air loss rate that is safe for your specific vehicle. A triple combination should have a leakage rate no higher than 6 psi in a minute during an applied leakage test.

In an air brake system, the air storage tanks hold compressed air to be used by the brakes. The number and size of air tanks varies among vehicles.

A vehicle that is equipped with air brakes must also be equipped with a supply pressure gauge. This gauge tells the driver how much air pressure is in each of the vehicle's air tanks.

In situations where a driver cannot use a parking brake, wheel chocks can be used to hold a parked vehicle in place on a level surface.

Before driving a vehicle with air brakes, you should ensure that the spring brakes come on automatically when air tank pressure falls to a level between 20 and 45 psi. You can do this by chocking the wheels and releasing air from the braking system by stepping on and off the brake pedal. Once the pressure levels drop to an unsafe level, the parking brake valve should pop out and spring brakes should come on.

Compressed air in an air brake system usually has a certain amount of water and oil in it. This can harm the system if allowed to accumulate. Air tanks have drain valves to aid in removing water and oil from the compressed air.

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.

An air compressor governor will stop the compressor from pumping air once the air tanks are at an air pressure level around 125 psi. This air pressure level is referred to as the "cut-out" level.

If you need to make an emergency stop, you can use either the controlled braking method or the stab braking method. It's important to brake in a way that keeps your vehicle in a straight line but will still allow you to turn if necessary.

Air brakes are really three different braking systems: the service brake, the parking brake, and the emergency brake. Emergency and parking brakes are applied with mechanical force.

Friction inside a brake drum is caused when the brake shoes and linings push against the inside of the drum. The friction in the drums will slow and stop the vehicle.

When parking on a level surface, you should use wheel chocks. If the vehicle is not equipped with spring brakes, this is essential to prevent the trailer from moving.

If equipped, ABS is in addition to a vehicle's normal braking system and does not increase or decrease the braking power of any other system. ABS only activates when a vehicle's wheels are about to lock.

Components of an air brake system include an air compressor, an air compressor governor, air storage tanks, air tank drains, an alcohol evaporator, a safety valve, a brake pedal, foundation brakes, supply pressure gauges, an application pressure gauge, a low air pressure warning signal, a stop light switch, a front brake limiting valve (on some older vehicles), spring brakes, and parking brake controls.

A modulating control valve allows a driver to gradually apply spring brakes. In equipped vehicles, the valve is controlled by a lever located on the dashboard.

In an air brake system, the air compressor governor controls when the air compressor pumps air into the air storage tanks.

Never push down the brake pedal while the spring brakes are activated. The combined force of springs and air pressure could damage the brakes.

When performing a static leakage test on a triple combination vehicle with air brakes, the leakage rate should be no more than 5 psi in one minute. If the air leaks from the air brake system at a quicker rate, the vehicle should not be driven because something likely needs to be repaired.

Vehicles with air brakes are required to be equipped with a low pressure warning device. A wig wag is a type of low air pressure warning device. This device drops a mechanical arm into the driver's view if the pressure in the tanks drops to a level between 55 and 75 psi.

In a dual air brake system, either the front or rear brakes will not be fully operable if one of the air systems gets too low on pressure. If the air pressure in either tank gets too low while you are driving, you should exit the road and park as soon as possible.

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.