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Drivers who want to drive combination vehicles must pass the combination vehicles test. The Iowa 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 Iowa CDL Manual. Take this practice test now to prepare for the actual IA CDL combination test!
1. Which of the following is NOT part of the procedure to raise the landing gear?
Safely securing the crank handle, after raising the landing gear
Using the high range gear, if equipped, to begin raising the landing gear
Raising the landing gear all the way up
2. If you are being tailgated, you should:
move to the left lane.
speed up.
increase your following distance.
3. If the safety relief valve in the air brake system releases air:
something is wrong.
the valve is fully operational.
this will supply more power to the brakes.
4. When you get ready to back under the semi-trailer, you should:
line up directly in front of the trailer.
line up about 15 degrees off the line of the trailer.
back under the trailer at an angle to avoid pushing the trailer sideways.
5. During a trip:
you should not watch gauges as they can be misleading.
you should watch gauges for signs of trouble.
you should watch gauges to make sure that valve caps are not missing.
6. Tests have shown that trucks with a high center of gravity:
are less likely to roll over when entering a curve.
can roll over if the driver exceeds the posted speed limit for a curve.
can roll over at the posted speed limit for a curve.
7. When going down grades, you should:
put the transmission in Neutral.
downshift to a lower gear.
shift up.
8. Axle weight is:
the weight of all the axles added together.
the maximum safe weight your tires can carry at a specified pressure.
the weight transmitted to the ground by one axle or one set of axles.
9. The best way to recognize that your trailer has started to skid is:
by seeing it in your mirrors.
by recognizing tire failure.
by feeling the brakes come on.
10. If the ABS is not working:
you still have normal brake functions.
the vehicle will have weak brakes.
the vehicle will have no brakes.
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CDL Combination Test (IA)

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