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Drivers who want to drive combination vehicles must pass the combination vehicles test. The North Carolina 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 North Carolina CDL Manual. Take this practice test now to prepare for the actual NC CDL combination test!
1. Before driving a vehicle with a dual air brake system, you should allow time for the air compressor to build up a minimum of ____ pressure in both the primary and secondary systems.
150 psi
50 psi
100 psi
35 psi
2. While driving, you should use your mirrors to:
check where the rear of your vehicle is while you make turns.
check the condition of the tires and cargo.
know where other vehicles are around you.
All of the above.
3. If your vehicle gets stuck on the railroad tracks, you should:
gather up your paperwork and shipping papers while calling 911, then get out of the vehicle.
check for identifiable landmarks to give the location of the crossing.
get out of your vehicle and away from the tracks.
All of the above.
4. If a trailer does not have spring brakes, to keep the trailer from moving you should:
close the brake valve.
use wheel chocks.
park on a slight decline.
use the service brakes.
5. When backing a trailer, you should:
not back up in a straight line.
turn the steering wheel toward the direction you want to go.
pull-up frequently to reposition the vehicle.
avoid braking.
6. If loose or missing, _______ may cause movement between the frame and fifth wheel assembly.
safety chains
locking pins
electric connectors
mounting bolts
7. Cargo should be properly covered:
to protect people from spilled cargo.
to block your view or someone else’s.
to protect the weather from the cargo.
All of the above.
8. Foundation brakes are used:
only with the rear wheels.
only with the front wheels.
at each wheel.
only with the right wheels.
9. To prevent rollover, you should:
keep the cargo as close to the ground as possible.
drive slowly around on ramps and off ramps.
go slowly around turns.
All of the above.
10. When uncoupling, after you unlock the fifth-wheel you should:
chock the trailer wheels.
pull the tractor clear of the trailer.
pull the tractor partially clear of the trailer.
ease the pressure on the locking jaws.
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NC CDL Combination Test

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