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District Of Columbia CDL Combination Test 1
Practice mode
Question
1
of 20
QUESTION 1 / 20
Failure to keep the fifth wheel plate properly greased could:
Choose one answer below.
A
Cause the trailer to disconnect.
✓
B
Cause steering problems.
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C
Cause braking problems.
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D
Affect the lights.
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QUESTION 2 / 20
If a parked trailer does not have spring brakes, you should keep the trailer from moving by:
Choose one answer below.
A
Using the air brakes.
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B
Using wheel chocks.
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C
Parking near a wall.
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D
Parking on a slight incline.
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QUESTION 3 / 20
A combination vehicle has:
Choose one answer below.
A
One air line.
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B
Two air lines.
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C
Three air lines.
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D
Four air lines.
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QUESTION 4 / 20
Avoid needing to make sudden lane changes by:
Choose one answer below.
A
Using your horn to encourage other drivers to move out of your lane.
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B
Only driving slower than the posted speed limit.
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C
Watching the road ahead while driving.
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D
Pulling off the road and waiting when there is high traffic.
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QUESTION 5 / 20
During a trip, which shut-off valves should be open?
Choose one answer below.
A
All shut-off valves should be open.
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B
The rear shut-off valves should be open.
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C
All shut-off valves should be in the open position, except the rear shut-off valves.
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D
No shut-off valves should be open.
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QUESTION 6 / 20
In a combination rig, it is best to make:
Choose one answer below.
A
Quick, sudden stops.
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B
Sharp turns.
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C
Quick accelerations.
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D
Slow, planned stops.
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QUESTION 7 / 20
If a load is placed on one side of a trailer, the trailer:
Choose one answer below.
A
May lean, and could result in a rollover.
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B
May add extra support during turns.
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C
Have improved braking.
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D
Have improved steering.
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QUESTION 8 / 20
To prevent a trailer from rolling over, you should:
Choose one answer below.
A
Speed up when nearing a corner.
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B
Make sudden steering moves.
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C
Take on-ramps faster than the posted speed limit.
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D
Drive slowly around corners.
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QUESTION 9 / 20
When the wheels of a trailer lock up:
Choose one answer below.
A
The trailer will stay straight.
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B
The trailer tends to swing around.
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C
The cab will swing, but the trailer will stay straight.
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D
They will likely go flat.
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QUESTION 10 / 20
If unsure if a trailer is equipped with ABS, you can:
Choose one answer below.
A
Check under the trailer for wheel speed sensors coming from the back of the brakes.
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B
Try driving on a slippery surface and see if ABS kicks in.
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C
Assume it does have ABS.
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D
Remove a tire and look for the ABS sensor on the axle.
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QUESTION 11 / 20
Which of the following types of vehicles is most prone to the “crack-the-whip" effect?
Choose one answer below.
A
An automobile
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B
A three-axle tractor
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C
A bobtail tractor
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D
A triple combination
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QUESTION 12 / 20
A shut-off valve:
Choose one answer below.
A
Is located on the front of a trailer.
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B
Is located on the instrument panel.
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C
Prevents air from escaping an air brake system.
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D
Should always be open.
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QUESTION 13 / 20
Using the trailer hand brake while experiencing a trailer jackknife will:
Choose one answer below.
A
Stop the skid.
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B
Straighten the trailer.
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C
Increase traction.
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D
Continue the skid.
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QUESTION 14 / 20
In a sudden turn, the ____ trailer is the most likely to turn over.
Choose one answer below.
A
Front
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B
Last
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C
Middle
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D
First
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QUESTION 15 / 20
When driving a tractor-trailer equipped with ABS, you should:
Choose one answer below.
A
Stop harder than you would otherwise.
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B
Use extra braking force to ensure the ABS kicks in.
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C
Brake as you normally would.
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D
Brake using less pressure than you would otherwise use.
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QUESTION 16 / 20
If colors are being used to distinguish glad hands, which color is used for emergency lines?
Choose one answer below.
A
Orange
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B
Yellow
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C
Blue
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D
Red
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QUESTION 17 / 20
A tractor protection valve is:
Choose one answer below.
A
A device that keeps air in the tractor or truck brake system, should the trailer break away or develop a bad leak.
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B
A device that prevents theft.
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C
A device that controls fuel levels.
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D
A device that allows the battery to recharge efficiently.
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QUESTION 18 / 20
While inspecting a coupling, you should go under the trailer and:
Choose one answer below.
A
Detach the jaws from around the kingpin.
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B
Make sure the locking lever is in the "emergency" position.
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C
Remove the safety latch.
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D
Look into the back of the fifth wheel.
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QUESTION 19 / 20
Simply changing lanes can cause:
Choose one answer below.
A
A “crack-the-whip” effect, resulting in a rollover.
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B
A trailer to straighten out.
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C
Confusion over which lane the driver is hoping to use.
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D
Other drivers to reduce their speed.
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QUESTION 20 / 20
When driving a combination rig, following distance should be:
Choose one answer below.
A
Decreased in poor weather.
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B
Shorter than when driving a single vehicle.
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C
About the same as when driving a single vehicle.
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D
Longer than when driving a single vehicle.
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