CDL Airbrakes Practice Test

Question 1

What is the normal operating pressure range for a commercial vehicle air brake system?

Accepted Answer

100–125 psi

Answer

60–80 psi

Answer

140–160 psi

Answer

75–95 psi

Question 2

If the low air pressure warning activates while driving, what should you do?

Accepted Answer

Stop safely as quickly as possible

Answer

Pump the brakes to build pressure

Answer

Increase speed to reach a service station faster

Answer

Downshift and continue to the nearest exit

Question 3

What does the air pressure governor control in an air brake system?

Accepted Answer

When the air compressor pumps air into the reservoir

Answer

The amount of braking force applied to each wheel

Answer

The release of air from the brake chambers

Answer

The pressure in the brake lines during application

Question 4

What is the purpose of the air dryer in an air brake system?

Accepted Answer

To remove moisture and oil from compressed air before it enters the tanks

Answer

To cool the compressed air to prevent overheating

Answer

To increase air pressure above compressor output

Answer

To regulate brake application force

Question 5

During a pre-trip inspection of air brakes, you apply the parking brake and release the service brake. Air pressure should not drop more than ____ in one minute.

Accepted Answer

2 psi

Answer

5 psi

Answer

10 psi

Answer

1 psi

Question 6

What are spring brakes, and when do they apply?

Accepted Answer

Mechanically-applied brakes that activate automatically when air pressure falls too low

Answer

Air-powered brakes that engage at high speeds

Answer

Supplemental brakes on the trailer only

Answer

Electric brakes that back up the air system