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CDL Air Brake Practice Test
Questions And Verified Answers
Modern air brakes systems combine three different systems. They are the service,
parking, and the _________ brakes.
a. Emergency
b. Foot
c. S-cam
d. Drum - correct-answer - a. Emergency
To check the free play of the manual slack adjusters on the S-cam brakes, you
should park on:
a. Level ground with the parking brake on, then apply the service brake.
b. Level ground, chock the wheels, and turn off the parking brakes.
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c. Level ground and drain off air pressure before adjusting.
d. A slight grade, release the parking brake, apply the service brake and check for
vehicle movement. - correct-answer - b. Level ground, chock the wheels, and turn
off the parking brakes.
Of the choices below, the first thing to do when a low air pressure warning comes
on is:
a. Stop and safely park as soon as possible.
b. Shift to next higher gear.
c. Adjust the brake pedal for more travel.
d. Open the air supply control valve. - correct-answer - a. Stop and safely park as
soon as possible.
The air compressor governor controls:
a. The speed of the air compressor.
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b. When the brake chambers release pressure.
c. Air pressure is applied to the brakes.
d. When air is pumped into the air tanks. - correct-answer - d. When air is
pumped into the air tanks.
The braking power of the spring brakes:
a. Is not affected by the condition of the service brakes.
b. Can only be tested by highly trained brake service people.
c. Depends on the service brakes being in adjustment.
d. Increases when the service brakes are hot. - correct-answer - c. Depends on the
service brakes being in adjustment.
To test air service brakes, you should brake firmly when moving slowly forward.
The brakes are "OK" if you notice:
a. A delayed stopping action.
CDL Air Brake Practice Test
Questions And Verified Answers
Modern air brakes systems combine three different systems. They are the service,
parking, and the _________ brakes.
a. Emergency
b. Foot
c. S-cam
d. Drum - correct-answer - a. Emergency
To check the free play of the manual slack adjusters on the S-cam brakes, you
should park on:
a. Level ground with the parking brake on, then apply the service brake.
b. Level ground, chock the wheels, and turn off the parking brakes.
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c. Level ground and drain off air pressure before adjusting.
d. A slight grade, release the parking brake, apply the service brake and check for
vehicle movement. - correct-answer - b. Level ground, chock the wheels, and turn
off the parking brakes.
Of the choices below, the first thing to do when a low air pressure warning comes
on is:
a. Stop and safely park as soon as possible.
b. Shift to next higher gear.
c. Adjust the brake pedal for more travel.
d. Open the air supply control valve. - correct-answer - a. Stop and safely park as
soon as possible.
The air compressor governor controls:
a. The speed of the air compressor.
, 3|Page
b. When the brake chambers release pressure.
c. Air pressure is applied to the brakes.
d. When air is pumped into the air tanks. - correct-answer - d. When air is
pumped into the air tanks.
The braking power of the spring brakes:
a. Is not affected by the condition of the service brakes.
b. Can only be tested by highly trained brake service people.
c. Depends on the service brakes being in adjustment.
d. Increases when the service brakes are hot. - correct-answer - c. Depends on the
service brakes being in adjustment.
To test air service brakes, you should brake firmly when moving slowly forward.
The brakes are "OK" if you notice:
a. A delayed stopping action.
