Maryland CDL Air Brakes Exam With
Actual Questions & Correct Answers,
Plus Rationales/Expert Verified For
Guaranteed Pass 2026/Latest
Update/Instant Download Pdf
1. What is the main purpose of an air brake system?
A. Increase fuel efficiency
B. Provide braking force using compressed air
C. Reduce tire wear
D. Improve steering control
Answer: B
Rationale: Air brake systems use compressed air to apply
braking force, making them suitable for heavy vehicles.
2. What happens if the air compressor fails?
A. Brakes become stronger
B. Air pressure increases
C. Air pressure will drop and brakes may fail
D. Nothing happens
Answer: C
Rationale: Without the compressor, air pressure decreases,
leading to possible brake failure.
3. What is the normal operating air pressure range?
A. 50–70 psi
B. 80–100 psi
C. 100–125 psi
, D. 130–150 psi
Answer: C
Rationale: Most systems operate between 100–125 psi for safe
braking.
4. What device removes moisture from compressed air?
A. Governor
B. Air dryer
C. Slack adjuster
D. Brake chamber
Answer: B
Rationale: Air dryers prevent moisture buildup that could freeze
or corrode components.
5. What is the function of the governor?
A. Controls braking force
B. Controls compressor operation
C. Stores air
D. Applies brakes
Answer: B
Rationale: The governor regulates when the compressor cuts in
and out.
6. When does the low air pressure warning activate?
A. Below 100 psi
B. Below 80 psi
C. Below 60 psi
D. Below 40 psi
Answer: C
Rationale: Warning typically activates around 60 psi to alert
drivers.
Actual Questions & Correct Answers,
Plus Rationales/Expert Verified For
Guaranteed Pass 2026/Latest
Update/Instant Download Pdf
1. What is the main purpose of an air brake system?
A. Increase fuel efficiency
B. Provide braking force using compressed air
C. Reduce tire wear
D. Improve steering control
Answer: B
Rationale: Air brake systems use compressed air to apply
braking force, making them suitable for heavy vehicles.
2. What happens if the air compressor fails?
A. Brakes become stronger
B. Air pressure increases
C. Air pressure will drop and brakes may fail
D. Nothing happens
Answer: C
Rationale: Without the compressor, air pressure decreases,
leading to possible brake failure.
3. What is the normal operating air pressure range?
A. 50–70 psi
B. 80–100 psi
C. 100–125 psi
, D. 130–150 psi
Answer: C
Rationale: Most systems operate between 100–125 psi for safe
braking.
4. What device removes moisture from compressed air?
A. Governor
B. Air dryer
C. Slack adjuster
D. Brake chamber
Answer: B
Rationale: Air dryers prevent moisture buildup that could freeze
or corrode components.
5. What is the function of the governor?
A. Controls braking force
B. Controls compressor operation
C. Stores air
D. Applies brakes
Answer: B
Rationale: The governor regulates when the compressor cuts in
and out.
6. When does the low air pressure warning activate?
A. Below 100 psi
B. Below 80 psi
C. Below 60 psi
D. Below 40 psi
Answer: C
Rationale: Warning typically activates around 60 psi to alert
drivers.
