CDL AIR BRAKES

Why must air tanks be drained?

A. To drain all the air out of the tank.
B. To keep anyone from moving the vehicle.
C. To drain moisture and oil out of the tank.

What is a supply pressure gauge used for?

A. To tell you how much diesel is in the vehicle.
B. To tell you how much water is in the air tank.
C. To tell you how much air is in the air tanks.

All vehicles with air brakes must have a low air pressure warning signal.

A. True
B. False

What are spring brakes?

A. The spring on the brake pedal.
B. If the airbrakes leak down, springs press the brakes on to stop the vehicle.
C. Brakes used for parking.

Front wheel brakes are good under all conditions.

A. True
B. False

When you apply your brakes, the air brake system works with an electric switch, by air pressure, to turn on the brake lights.

A. True
B. False

What do air brakes use to make the brakes work?

A. Compressed oil
B. Compressed gas
C. Compressed air

Air brakes are really three different braking systems: service brake, parking brake and emergency brake.

A. True
B. False

The service brake applies and releases:

A. The brake when you use the brake pedal during normal driving.
B. In the event of an emergency.
C. The parking brake when you use the parking brake control.

The parking brake applies and releases:

A. In the event of an emergency.
B. The parking brakes when you use the parking brake control.
C. The brake pedal during normal driving.

The emergency brake system:

A. Uses the service brake to stop the vehicle in the event of a brake system failure.
B. Uses the parking brake to stop the vehicle in the event of a brake system failure.
C. Uses parts of the service and parking brake system to stop the vehicle in the event of a brake system failure.

The governor controls when the air compressor will pump into the air storage tanks.

A. True
B. False

The air storage tanks are used to hold compressed air.

A. True
B. False

When you put on the brakes by pushing down the brake pedal:

A. The air pressure is reduced to the brake pads.
B. Air pressure is applied to the brake pads.
C. Compressed air is let go out of the system.

The S-cam forces the brake shoes away from one another and presses them against the inside of the brake drum. It is called the S-cam because:

A. It is shaped like the letter Z.
B. It is shaped like the letter N.
C. It is shaped like the letter S.

The air compressor is connected to the engine through:

A. Gears
B. Hoses
C. V Belt
D. Both A and C

The Air Compressor Governor controls:

A. When the air is released from the tank
B. When the warning light is activated
C. When the brakes should be applied
D. When the air compressor pumps air into the storage tanks

Compressed air is stored:

A. In the fuel tank
B. In the hoses
C. In the engine compartment
D. In the storage tank

The Governor stops pumping air when it reaches the "cut out" level, or around:

A. 175 psi
B. 225 psi
C. 125 psi
D. 200 psi

The Governor allows the air to start pumping again when it reaches the cut in level, or around:

A. 125 psi
B. 200 psi
C. 150 psi
D. 100 psi

An air tank is equipped with a drain valve to remove:

A. Air and water
B. Oil and air
C. Dirt and oil
D. Water and oil

Some air brake systems have an alcohol evaporator which helps:

A. Remove oil from the air lines
B. Reduce the risk of water in the air brake valves in warm weather
C. Remove fuel from the air lines
D. Reduce the risk of ice in the air brake valves during cold weather

The air tank should be drained how often?

A. Once a day
B. Every two or three days
C. Every four hours
D. Once a week

The safety valve in the air compressor tank is set to open at:

A. 150 psi
B. 100 psi
C. 200 psi
D. 175 psi

When the safety valve releases air it means that:

A. The pressure has exceeded 150 psi
B. Too much air is in the air compressor
C. Something is wrong, and you should have it checked by a mechanic
D. All of the above

When you apply pressure to the brake pedal, you are:

A. Releasing air pressure to the brakes
B. Activating the safety valve
C. Reducing air in the tanks
D. Pushing against a spring and against air pressure to the brakes

Brake drums:

A. Are bolted to the wheels
B. Are located at each end of the vehicle's axles
C. Hold the brake shoes and linings
D. All of the above

Which type of brake is the most common in commercial vehicles?

A. Disk brakes
B. Wedge brakes
C. S Cam brakes
D. Drum brakes

An air pressure gauge:

A. Is connected to the generator
B. Shows how much pressure you are applying to the brakes
C. Prevents brake failure
D. Releases air when you accelerate

All vehicles with air bakes are required to have a low pressure warning signal. This could be:

A. A red light
B. A wig wag mechanical arm
C. A buzzer
D. Any one of the above

When the low pressure warning is activated, you should:

A. Monitor your air pressure gauge and maintain highway speeds
B. Wait for the air brakes to come on automatically
C. Pump the brake pedal hard to stop
D. Bring the vehicle to a safe stop while you still control the brakes

A dual air brake system:

A. Must have two warning alarms
B. Has one set of air tanks and hoses
C. Takes less time to build air pressure
D. Has two air brake systems and one set of controls

An emergency brake:

A. Is required on commercial vehicles
B. Must be held on by mechanical force
C. Could be activated by the loss of air pressure
D. All of the above

To check the slack adjusters on S Cam brakes, you should:

A. Drain the air from the system and pull on the slack adjusters
B. Make sure the slack adjusters move more than one inch each way
C. Leave the parking brakes on and pull on the slack adjuster
D. Wear gloves and pull hard on each slack adjuster

To test the low pressure warning signal, you should do all BUT the following:

A. Turn the electrical power on
B. Shut the engine off
C. Ask a friend to listen for the signal
D. Step on and off the brake pedal to reduce air pressure

With dual air systems, the air pressure should build:

A. From 85 to 150 psi in 45 seconds
B. From 70 to 100 psi in 60 seconds
C. From 70 to 150 psi in 60 seconds
D. From 85 to 100 psi in 45 seconds

A fully charged air system typically has ____ psi:

A. 125
B. 100
C. 175
D. 150

To test air leakage rate you should:

A. Depress the brake pedal and monitor the air pressure gauge
B. Charge the air system and leave the engine running
C. Turn off the engine and release the service brake
D. Leave the engine running and release the service brake

A combination vehicle air brake system should not lose air faster than:

A. 3 psi per 30 seconds
B. 2 psi per minute
C. 3 psi per minute
D. 4 psi per minute

To check the air compressor governor "cut in" and "cut out" pressures:

A. Run the engine at a fast idle
B. Step on and off the brake to reduce tank pressure
C. Monitor the air pressure gauge
D. All of the above

To test your service brakes you should:

A. Put parking brake on and release air pressure
B. Release the parking brake, move forward slowly and depress brakes
C. Depress brakes when traveling at highway speeds
D. Stop the vehicle and put the parking brake on

Stab braking occurs when you:

A. Press on the brake pedal as hard as you can
B. Release the brakes when the wheels lock up
C. Apply the brakes when the wheels start rolling
D. All of the above

Air brakes take longer to stop than hydraulic brakes because:

A. The reaction time is longer for the driver
B. It takes longer for the air to flow through the lines
C. The linings get hotter more quickly
D. None of the above

The proper way to go down long grades is to:

A. Use a low gear and push hard on the brakes
B. Use a low gear and apply light pressure on the brakes
C. Brake on and off down the hill
D. Let up on the brakes from time to time to cool them

You should use the parking brake:

A. On level surfaces
B. Any time you park
C. Only on steep hills
D. When the brakes are hot