NC CDL AIR BRAKES EXAM 2025
QUESTIONS AND ANSWERS
Oil and water usually collect in compressed air tanks. If you do not have an automatic tank
drain, when should you drain the air tanks? - ANS After every working day
Why drain water from the compressed air tanks? - ANS Water can freeze in cold weather and
cause brake failure.
The air brake system for a straight truck or bus should not leak at a rate of more than ___ PSI
per minute with the engine off and the brakes released. - ANS 2
To make an emergency stop with air brakes using the stab braking method, you should: -
ANS Press on the brake pedal as hard as you can, release the brakes when the wheels lock,
put on the brakes again when the wheels start rolling.
You should know that your brakes are fading when: - ANS You have to apply the brake pedal
harder to control speed on a downgrade.
If the air compressor should develop a leak, what keeps the air in the tanks? - ANS The one-
way check valve.
To check the brake slack on S-cam brakes you should: - ANS Park on level ground, chock the
wheels, and release the parking brake.
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@COPYRIGHT FYNDLAY 2025/2026
, The application pressure gauge shows how much pressure you have: - ANS When you are
applying the brakes.
The spring brakes used on the chambers in a straight truck will bring you to a stop when air
pressure drops below ___ PSI. - ANS 20
The safety valve is set to automatically reduce pressure at ___ PSI. - ANS 150
Your truck has a dual air system and one of the system loses its pressure. What will happen? -
ANS Either the front or back brake will not be fully operational.
If your truck or bus has dual parking control valves, you can use pressure from a separate tank
to: - ANS Release the spring emergency/parking brakes to move a short distance.
During normal driving, spring brakes are usually held back by: - ANS Air pressure.
During normal driving, spring brakes are usually held back by: - ANS Air pressure.
The air compressor stops pumping air at what PSI? - ANS 125
The driver must be able to see a warning before pressure in the service air tanks falls below ___
PSI. - ANS 55
Excessive use of the service brakes results in overheating, which can lead to: - ANS Expansion
of the brake drums.
The most common type of foundation brakes found on heavy vehicles is the: - ANS S-cam
drum.
2
Page
@COPYRIGHT FYNDLAY 2025/2026
QUESTIONS AND ANSWERS
Oil and water usually collect in compressed air tanks. If you do not have an automatic tank
drain, when should you drain the air tanks? - ANS After every working day
Why drain water from the compressed air tanks? - ANS Water can freeze in cold weather and
cause brake failure.
The air brake system for a straight truck or bus should not leak at a rate of more than ___ PSI
per minute with the engine off and the brakes released. - ANS 2
To make an emergency stop with air brakes using the stab braking method, you should: -
ANS Press on the brake pedal as hard as you can, release the brakes when the wheels lock,
put on the brakes again when the wheels start rolling.
You should know that your brakes are fading when: - ANS You have to apply the brake pedal
harder to control speed on a downgrade.
If the air compressor should develop a leak, what keeps the air in the tanks? - ANS The one-
way check valve.
To check the brake slack on S-cam brakes you should: - ANS Park on level ground, chock the
wheels, and release the parking brake.
1
Page
@COPYRIGHT FYNDLAY 2025/2026
, The application pressure gauge shows how much pressure you have: - ANS When you are
applying the brakes.
The spring brakes used on the chambers in a straight truck will bring you to a stop when air
pressure drops below ___ PSI. - ANS 20
The safety valve is set to automatically reduce pressure at ___ PSI. - ANS 150
Your truck has a dual air system and one of the system loses its pressure. What will happen? -
ANS Either the front or back brake will not be fully operational.
If your truck or bus has dual parking control valves, you can use pressure from a separate tank
to: - ANS Release the spring emergency/parking brakes to move a short distance.
During normal driving, spring brakes are usually held back by: - ANS Air pressure.
During normal driving, spring brakes are usually held back by: - ANS Air pressure.
The air compressor stops pumping air at what PSI? - ANS 125
The driver must be able to see a warning before pressure in the service air tanks falls below ___
PSI. - ANS 55
Excessive use of the service brakes results in overheating, which can lead to: - ANS Expansion
of the brake drums.
The most common type of foundation brakes found on heavy vehicles is the: - ANS S-cam
drum.
2
Page
@COPYRIGHT FYNDLAY 2025/2026
