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Iowa CDL Permit Test - Combination

(From the 2020 Iowa CDL driver handbook)
Number of questions: 20
Passing score: 16
Directions: All applicants who are applying for a Class A CDL should be prepared to take the Combination test. This test covers information found in Section 6 of the Commercial Driver License Manual. Section 6 provides the information needed to safely operate tractor-trailers, doubles, triples, and straight trucks with trailers. The test is made up of 20 multiple-choice questions, and applicants will need to correctly answer a minimum of 16 questions to pass. The Combination test is not a replacement for the Double/Triple endorsement test.
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Passing grade —
4 or fewer errors
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1.
In a vehicle equipped with an automatic tractor protection valve, the valve will pop out when air pressure drops to a level between:
20 and 45 psi.
75 and 105 psi.
50 and 65 psi.
2.
If a trailer begins to jackknife, the driver:
Should not apply the trailer hand brake.
Should firmly apply the brakes.
Can straighten the trailer with the parking brake.
3.
To prevent a rollover, cargo should be:
Loaded with most weight on the driver’s side of the trailer.
Placed near the rear of the trailer.
Spread out in the trailer.
4.
Before a trip, you can make sure air flows to all trailers by:
Checking for moving air inside of each trailer.
Listening for air at the rear shut-off valve.
Feeling for air at the front shut-off valve.
5.
What is the tractor protection valve?
A valve that keeps air in the brake system should a bad leak occur
A valve that prevents the trailer from being accidentally released
A valve that prevents the vehicle from going too fast
6.
When backing up your tractor while coupling it to a trailer, the trailer brakes should be:
Deactivated.
Locked.
Unlocked.
7.
When coupling a trailer:
Make sure to couple the proper glad hands.
Glad hands can be connected to any other glad hands.
Only one set of glad hands should be connected.
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