Air Brakes Flashcards
TRUE or FALSE The use of brakes on a long steep downgrade is only a supplement to the braking effect of the engine
TRUE
How often should drain air tanks?
Drain your air tanks at the end of each working day
What is a supply pressure gauge used for?
The gauges tell you how much pressure is in the air tanks
How can you check slack adjusters?
By pulling hard on each slack adjuster.
What are the maximum leakage rates for an air brake system?
The loss rate should be less than two psi in one minute for single vehicles and less than three psi in one minute for combination vehicles.
Why must air tanks be drained?
To keep oil and water from building up in the tank.
TRUE or FALSE all vehicles with air brakes must have a low air pressure warning signal
TRUE
What factors can cause brakes to fade or fail?
- brakes can fade or fail from excessive heat caused by using them too much
- brakes that are out of adjustment
TRUE or FALSE Front wheel brakes are good under all conditions?
TRUE
What are spring brakes?
Powerful springs that are held back by air pressure. If the air pressure is removed, the springs put on the brakes.
Why should you be in the proper gear before starting down a hill?
Brakes can fade or fail from excessive heat caused by using them too much and not relying on the engine break effect.
TRUE or FALSE if you are away from your vehicle only a short time, you don’t need to use the parking brake?
FALSE
What are the slack adjusters?
A lever connecting the brake chamber push rod with the foundation brake camshaft
What is a dual air brake system?
A dual air break system has two separate air brake systems, the first system is called primary and the other secondary
How can you check that the spring brakes will come on automatically?
Step on and off the brake pedal to reduce the air tank pressure, the parking brake knob should pop out when the air pressure falls to the manufacturers specification
How can you test the low pressure warning signal?
Turn the electrical power on and step on and off the brake pedal to reduce air tank pressure. The low air pressure warning signal must come on before the pressure drops to less than 60 psi in the air tank
Modern air brake systems combine three different systems. They are the service brakes, the parking brakes and the:
Emergency brakes
Oil and water usually collect in compressed air tanks. If you do not have automatic tank drain, when should you drain the air tanks?
After every working day
Why drain water from the compressed air tanks?
Water can freeze in cold weather and cause brake failure.
Air brake equipped vehicles must have:
A supply pressure gauge
What can legally hold a parking or emergency brake in position for a truck, tractor or bus?
Spring pressure
Air loss in a straight truck or bus should not be more than _ with the engine off and brakes on
3 psi in one minute
To make an emergency stop with air brakes, using the stab braking method, you should:
Brake as hard as you can, get off the brakes when the wheels lock, get back on the brakes when the wheels start rolling again.
You should know that your brakes are fading when:
You have to push harder on the brake pedal to control your speed on a downgrade
To check the free play of manual slack adjusters on s-cam brakes you should:
Park on level ground, chock the wheels, and release the parking brakes.
If the air compressor should develop leak, what keeps the air in the tanks?
The one way check valve
When driving down a long steep hill you should:
Release the brake when you are 5 mph below your safe speed
The brake system thy applies and releases the brakes when the driver uses the brake pedal is the:
Service brake system
The most common type of foundation brakes found on heavy vehicles is the:
S-cam drum
Vehicles with air brakes must have:
An air pressure gauge to show the pressure available for braking
The driver must be able to see a warning that is given before air pressure on the derive air tanks falls below:
60 psi
Which of the following makes the total stopping distance for air brakes longer than that for hydraulic brakes
Brake lag distance
The first thing to do when a low air pressure warning comes on is:
Stop and safely park asap
The braking power of spring brakes:
Depends on the adjustment of the service brakes
The air compressor governor controls:
When air is pumped into the air tanks
The application pressure gauge shows the driver how much pressure:
Is being applied to the brakes
If the vehicle has an alcohol evaporator, every day during could weather you should:
Check and fill the alcohol level.
During normal driving, spring brakes are usually held back by:
Air pressure.
Air braking takes more time than hydraulic braking because air brakes:
Need to have airflow through the lines to work.
In air brake vehicles, the parking brakes should be used:
Whenever the vehicle is parked.
The brake pedal in an air brake system:
Controls the air pressure applied to put on the brakes.
If your truck or bus has dual parking control valves it means that you can use pressure from a separate tank to:
Release the spring brakes to move a short distance.
A straight truck or bus air brake system should not leak at a rate of more than_ PSI per minute with the engine off and the brakes released.
2
If your vehicle has an alcohol evaporator, it is there to:
Reduce the risk of ice in air brake valves in cold weather.
If you must make an emergency stop, you should brake so that you;
Stay in a straight line and can steer
Your truck or bus has a du air brake system. If a low air pressure warning comes on for only one system, what should you do?
Stop. Safely park, and continue only after the system is fixed.
