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Drivers who want to drive combination vehicles must pass the combination vehicles test. The Colorado CDL combination test consists of 20 questions, and you'll need at least 16 correct answers to pass (80%). The test covers the combination vehicles section of the Colorado CDL Manual. Take this practice test now to prepare for the actual CO CDL combination test!
1. Air brakes use ________ to make the brakes work.
compressed oil
compressed gas cylinders
compressed air
compressed gases
2. Which of the following is most likely to roll over?
The rear trailer of a double
The middle trailer of a triple
The rear trailer of a triple
The front trailer of a double
3. When parking a trailer without spring brakes, it is very important for safety that you use wheel chocks. Why?
You may not notice a major leak in the service line until you try to put the brakes on.
if you don't use wheel chocks, supply air will be sent to the service line instead of going to charge the trailer air tanks.
The air could leak out of the trailer air tank, releasing its emergency brakes.
None of the above.
4. Combination vehicles _________ than single CMVs.
require more driving skill
are much easier to drive
are safer in bad weather
All of the above.
5. Which of the following is NOT a step in backing up with a trailer?
Backing quickly when the path is straight
Looking at your line of travel before you begin
Checking the outside mirrors on both sides frequently
Backing slowly
6. Off-tracking is:
when a vehicle makes a turn and the rear wheels of the trailer end up driving in a different path than the tractor and the front wheels of the trailer.
when a vehicle towing a trailer skids, and the trailer pushes the towing vehicle from behind until it spins the vehicle around.
when the tires lose their contact with the road and have little or no traction.
None of the above.
7. When you are uncoupling a loaded trailer, lower the landing gear until:
the tractor frame is under the trailer.
the pressure in the system is above 55 psi.
it makes firm contact with the ground.
makes contact with the ground, and leave the trailer off the fifth wheel.
8. When driving on slippery roads, you should NOT:
go slowly.
try to anticipate stops early.
use the engine brake.
watch far enough ahead to keep a steady speed.
9. Never drive with landing gear only part way up. Why?
It makes it harder to brake.
It must be exactly 5 feet off the ground.
It may be harder to use.
It may catch on railroad tracks.
10. After coupling the trailer, begin raising the landing gear by using:
the electrical cord.
the high gear range.
the crank handle.
the low gear range.
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CO CDL Combination Test

Number of questions: 20
Correct answers to pass:16
Passing score:80%
Number of questions: 20
Correct answers to pass:16
Passing score:80%
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