CDL Class B - Air Brakes Exam 2025
Questions and Answers
Air brakes use ____ to make the brakes work. - --CORRECT ANSWER--
Compressed air
The ____ brake system applies and releases the brakes when you use the brake
pedal during normal driving. - --CORRECT ANSWER--Service
The _____ brake system applies and releases the parking brakes when you use the
parking brake control. - --CORRECT ANSWER--Parking
The ______ brake system uses parts of the service and parking brake systems to
stop the vehicle in a brake system failure. - --CORRECT ANSWER--Emergency
What does the air compressor do? - --CORRECT ANSWER--The air compressor
pumps air into the storage tanks (reservoirs)
The air compressor is connected to the engine through ________. - --CORRECT
ANSWER--Gears or a v-belt
There are different kinds of air compressors. How may the air compressor be
cooled? - --CORRECT ANSWER---Air cooled
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 1
, -Engine cooling system
If the compressor has its own oil supply, what must you be sure to do? - --
CORRECT ANSWER--Check the oil level before driving
What does the air compressor governor do? - --CORRECT ANSWER--The
governor controls when the air compressor will pump air into the air storage tanks.
What do the air storage tanks do? - --CORRECT ANSWER--Used to hold
compressed air
When air tank pressure rises to the "cut-out" level, the governor stops the
compressor from pumping air. What level is the "cut-out" level? - --CORRECT
ANSWER--Around 125 pounds per square inch (psi)
When the tank pressure falls to the "cut-in" pressure, the governor allows the
compressor to start pumping again. What is the "cut-in" level? - --CORRECT
ANSWER--Around 100 pounds per square in (psi)
True or false? The number and size of air tanks varies among vehicles. The tanks
will hold enough air to allow the brakes to be used several times even if the
compressor stops working. - --CORRECT ANSWER--True
Compressed air usually has some water and some compressor oil in it which is bad
for the air brake system. Why is it bad for the air brake system? - --CORRECT
ANSWER--The water can freeze in cold weather and cause break failure
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 2
Questions and Answers
Air brakes use ____ to make the brakes work. - --CORRECT ANSWER--
Compressed air
The ____ brake system applies and releases the brakes when you use the brake
pedal during normal driving. - --CORRECT ANSWER--Service
The _____ brake system applies and releases the parking brakes when you use the
parking brake control. - --CORRECT ANSWER--Parking
The ______ brake system uses parts of the service and parking brake systems to
stop the vehicle in a brake system failure. - --CORRECT ANSWER--Emergency
What does the air compressor do? - --CORRECT ANSWER--The air compressor
pumps air into the storage tanks (reservoirs)
The air compressor is connected to the engine through ________. - --CORRECT
ANSWER--Gears or a v-belt
There are different kinds of air compressors. How may the air compressor be
cooled? - --CORRECT ANSWER---Air cooled
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 1
, -Engine cooling system
If the compressor has its own oil supply, what must you be sure to do? - --
CORRECT ANSWER--Check the oil level before driving
What does the air compressor governor do? - --CORRECT ANSWER--The
governor controls when the air compressor will pump air into the air storage tanks.
What do the air storage tanks do? - --CORRECT ANSWER--Used to hold
compressed air
When air tank pressure rises to the "cut-out" level, the governor stops the
compressor from pumping air. What level is the "cut-out" level? - --CORRECT
ANSWER--Around 125 pounds per square inch (psi)
When the tank pressure falls to the "cut-in" pressure, the governor allows the
compressor to start pumping again. What is the "cut-in" level? - --CORRECT
ANSWER--Around 100 pounds per square in (psi)
True or false? The number and size of air tanks varies among vehicles. The tanks
will hold enough air to allow the brakes to be used several times even if the
compressor stops working. - --CORRECT ANSWER--True
Compressed air usually has some water and some compressor oil in it which is bad
for the air brake system. Why is it bad for the air brake system? - --CORRECT
ANSWER--The water can freeze in cold weather and cause break failure
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 2
