Trivia Quiz: CDL Air Brake Practice Test
- 1.The air brake lag distance at 55 mph on dry pavement adds about ______ feet to your stopping distance?
- A.
12
- B.
52
- C.
32
- 2.The most important thing to do when a low air pressure warning comes on is?
- A.
Upshift and drive to a safe place.
- B.
Downshift and drive to a safe place.
- C.
Stop and safely park as soon as possible.
- 3.How should you check that your service brakes are working properly?
- A.
Park on a slight incline, drain off air pressure, set the parking brakes, and check for movement.
- B.
Wait for normal pressure, release the parking brake, move the truck forward slowly, and firmly step on the brake.
- C.
Park on level ground, chock the wheels, engage the parking brake, and shut the engine off.
- 4.The stop light switch:
- A.
Turns on the brake lights to warn drivers behind you.
- B.
Tells you when you need to use your emergency brakes.
- C.
Tells you when the air brake system is low on pressure.
- 5.If your vehicle has an alcohol evaporator, it is there to:
- A.
Rid the wet tank of alcohol that condenses and sits at the bottom.
- B.
Eliminates the need for daily tank draining.
- C.
Reduce the risk of ice in air brake valves in cold weather.
- 6.The most common type of foundation brake found on heavy vehicles is the:
- A.
Wedge drum.
- B.
S-Cam drum.
- C.
Disc brake.
- 7.During normal driving, spring brakes are usually held back by:
- A.
Bolts.
- B.
Spring pressure.
- C.
Air pressure.
- 8.A truck with air brakes going 55 mph would require a stopping distance of?
- A.
Less than 100 feet.
- B.
100-300 feet.
- C.
More than 300 feet.
- 9.Your truck has a properly functioning dual air brake system and minimum size air tanks. The air pressure should build from 85 to 100 psi within:
- A.
30 seconds.
- B.
45 seconds.
- C.
60 seconds.
- 10.If your truck has a dual air system and one of the systems is low on pressure:
- A.
The brake drums will not be fully pressurized.
- B.
Either the front or rear brakes will not be fully operational.
- C.
The manual slack adjusters on the S-cam brakes are not set properly.
- 11.In air brake vehicles, the parking brakes should be used:
- A.
As little as possible.
- B.
To hold your speed when going downhill.
- C.
Any time the vehicle is parked.
- 12.The braking power of the spring brakes:
- A.
Is not affected by the condition of the service brakes.
- B.
Depends on the service brake being in adjustment.
- C.
Increases when the service brakes are hot.
- 13.What is emergency stab braking?
- A.
Press hard on the brake pedal and apply full hand valve until you stop.
- B.
Use light, steady pressure on the brake pedal.
- C.
Brake hard, release the brakes when the wheels lock, and reapply the brakes when the wheels start rolling.
- 14.When you apply the brakes, the brake shoes/linings are pressed against the:
- A.
Brake drum or disc.
- B.
Slack adjuster.
- C.
S-cam.
- 15.The air compressor governor controls:
- A.
When air is pumped into the air tanks.
- B.
The speed of the air compressor.
- C.
Air pressure applied to the brakes.
- 16.What is emergency controlled braking?
- A.
You apply the brakes as hard as you can without locking the wheels.
- B.
You brake as hard as you can, release the brakes when the wheels lock, and reapply the brakes when the wheels start rolling.
- C.
You apply the hand valve for one second, then push hard on the brake pedal.
- 17.The driver must be able to see a low air pressure warning which comes on before pressure in teh service air tanks fall below ______ psi?
- A.
40
- B.
60
- C.
80
- 18.The safety valve is usually set to reduce air pressure at _____ psi.
- A.
50
- B.
100
- C.
150
- 19.Repeatedly pressing and releasing (fanning) the brake pedal may result in:
- A.
A loss of brake air pressure.
- B.
A build up of brake air pressure.
- C.
No change in brake air pressure.
- 20.The brake pedal in an air brake system:
- A.
Controls the speed of the air compressor.
- B.
Controls the air pressure applied to put on the brakes.
- C.
Is connected to slack adjusters by a series of rods and linkages.
- 21.If you must make an emergency stop, brake so you:
- A.
Can steer hard while braking hard.
- B.
Use the hand brake first.
- C.
Can steer your vehicle in a straight line.
- 22.Truck and bus parking or emergency brakes must be held on by:
- A.
Air pressure.
- B.
A modulating control valve.
- C.
Mechanical force.
- 23.You should know your brakes are fading when:
- A.
You have to push the brake pedal harder to control speed on a downgrade.
- B.
The brake pedal feels "spongy" when you apply pressure.
- C.
Your speed increases when you reduce pressure on your brake pedal.
- 24.The air compressor should stop pumping at about _____ psi.
- A.
100
- B.
125
- C.
150
- 25.The air loss rate for a straight truck or bus with the engine off and the brake on should not be more than:
- A.
1 psi in one minute.
- B.
2 psi in 45 seconds.
- C.
3 psi in one minute.
Questions: 20 | Attempts: 8484 | Last updated: May 16, 2019
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Sample QuestionWhy must air tanks be drained?
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