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District Of Columbia CDL Air Brakes Test 1
Practice mode
Question
1
of 25
QUESTION 1 / 25
Friction inside a brake drum is caused when the brake shoes and linings:
Choose one answer below.
A
Push against each other.
✓
B
Separate from the axle.
✓
C
Push against the inside of the drum.
✓
D
Create excess heat.
✓
QUESTION 2 / 25
If a vehicle has air brakes, the air compressor drive belt should be checked before each drive. In what condition should the belt be?
Choose one answer below.
A
Loose
✓
B
Tight
✓
C
Cracked
✓
D
Bumpy
✓
QUESTION 3 / 25
What is brake lag?
Choose one answer below.
A
The time required for the brakes to work after the brake pedal is pushed
✓
B
The distance between the brake pedal’s resting position and the floor
✓
C
The amount of air pressure used to stop a vehicle
✓
D
How faded the brakes are
✓
QUESTION 4 / 25
When the spring brakes are activated in a vehicle with air brakes, you should never:
Choose one answer below.
A
Turn on the lights.
✓
B
Turn the vehicle off.
✓
C
Push the brake pedal down.
✓
D
Open the trailer doors.
✓
QUESTION 5 / 25
While driving, spring brakes are generally held in place by:
Choose one answer below.
A
Air pressure.
✓
B
Chocks.
✓
C
Foundation brakes.
✓
D
Sturdy ties.
✓
QUESTION 6 / 25
The air storage tanks:
Choose one answer below.
A
Hold only enough air for one braking cycle.
✓
B
Hold enough air for brakes to be used several times if the compressor stops working.
✓
C
Do not hold air unless there is an emergency.
✓
D
Hold enough air for more than 1,000 braking cycles.
✓
QUESTION 7 / 25
Emergency brakes:
Choose one answer below.
A
Are not required on trucks.
✓
B
Are only required on trailers.
✓
C
Are required on tractors.
✓
D
Are optional.
✓
QUESTION 8 / 25
To confirm that a trailer has ABS, you can:
Choose one answer below.
A
Look under the trailer for wheel speed sensors coming from the back of the brakes.
✓
B
Look under the hood for the ABS sticker.
✓
C
Look at the tires.
✓
D
Remove a tire and look for the ABS sensor on the axle.
✓
QUESTION 9 / 25
An air compressor governor will stop the compressor from pumping air once the air tanks have an air pressure level of:
Choose one answer below.
A
125 psi.
✓
B
100 psi.
✓
C
150 psi.
✓
D
80 psi.
✓
QUESTION 10 / 25
Air tanks usually hold enough compressed air:
Choose one answer below.
A
For one stop before needing to be refilled.
✓
B
For several stops before needing to be refilled.
✓
C
For a day’s worth of braking.
✓
D
For an unlimited number of stops.
✓
QUESTION 11 / 25
If one air system in a dual air brake system is very low on pressure:
Choose one answer below.
A
None of the brakes will work at all.
✓
B
Either the front or rear brakes will not be operating fully.
✓
C
There will be no noticeable affect.
✓
D
Lights on the outside of the tractor will flash.
✓
QUESTION 12 / 25
An air brake-equipped vehicle traveling at a speed of 55 mph under ideal driving conditions will need approximately ____ to come to a complete stop.
Choose one answer below.
A
100 feet
✓
B
250 feet
✓
C
300 feet
✓
D
450 feet
✓
QUESTION 13 / 25
A low air pressure warning signal should activate:
Choose one answer below.
A
When tank pressure falls below 120 psi.
✓
B
When tank pressure falls below 60 psi.
✓
C
When tank pressure falls below 10 psi.
✓
D
When tank pressure falls below 5 psi.
✓
QUESTION 14 / 25
Braking mechanisms are located ____ a brake drum.
Choose one answer below.
A
Outside
✓
B
Inside
✓
C
Next to
✓
D
On top of
✓
QUESTION 15 / 25
What can happen if parking brakes are used in very wet weather with temperatures below freezing?
Choose one answer below.
A
The brakes will squeak.
✓
B
The brakes may freeze so the vehicle cannot move.
✓
C
The brakes may suddenly release by themselves.
✓
D
The brakes may become too smooth to be used.
✓
QUESTION 16 / 25
When you press the brake pedal in a vehicle with S-cam brakes, air pressure pushes out the rod and moves the:
Choose one answer below.
A
Slack adjuster.
✓
B
Axle.
✓
C
Brake drum.
✓
D
Alcohol evaporator.
✓
QUESTION 17 / 25
What color are ABS malfunction lamps?
Choose one answer below.
A
Orange
✓
B
Yellow
✓
C
Green
✓
D
Blue
✓
QUESTION 18 / 25
Air tank drains:
Choose one answer below.
A
Allow rain water to enter the tanks.
✓
B
Are used to drain water and oil from the air tanks.
✓
C
Should never be opened.
✓
D
Must remain open while driving.
✓
QUESTION 19 / 25
To stop in a vehicle that uses air brakes, the driver should:
Choose one answer below.
A
Pull the air brake lever.
✓
B
Engage the brake lever.
✓
C
Push the brake pedal down.
✓
D
Pull the brake pedal up.
✓
QUESTION 20 / 25
In a dual air brake system:
Choose one answer below.
A
Air tanks are shared by both systems.
✓
B
Each system has its own air tanks.
✓
C
You must designate which system you are using.
✓
D
Brakes on only one side of the vehicle will work.
✓
QUESTION 21 / 25
Applying the brake pedal causes air pressure to activate an electric switch and:
Choose one answer below.
A
Turn off the brake lights.
✓
B
Turn on the low pressure warning light.
✓
C
Turn on the brake lights.
✓
D
Turn off the low pressure warning light.
✓
QUESTION 22 / 25
Both systems in a dual air brake systems share:
Choose one answer below.
A
Air tanks.
✓
B
Hoses.
✓
C
Air lines.
✓
D
An air compressor.
✓
QUESTION 23 / 25
Most heavy-duty vehicles use ____ air brake systems.
Choose one answer below.
A
Single
✓
B
Dual
✓
C
Triple
✓
D
Quad
✓
QUESTION 24 / 25
All air tanks must include:
Choose one answer below.
A
A drain valve.
✓
B
A lock.
✓
C
A trap door.
✓
D
A warning sticker.
✓
QUESTION 25 / 25
What is a wig wag?
Choose one answer below.
A
A type of warning system
✓
B
A tube used to move air from the compressor to the tanks
✓
C
A noise made by air brakes when used
✓
D
A part within the braking unit that allows air to move freely
✓
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