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Drivers who want to drive combination vehicles must pass the combination vehicles test. The District of Columbia 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 District of Columbia CDL Manual. Take this practice test now to prepare for the actual DC CDL combination test!
1. Containerized loads:
should exceed gross weight and axle weight limits.
must be inspected before and after the trip.
are generally used for freight carried part way by rail or ship.
All of the above.
2. Do not use the trailer hand valve in driving because:
the trailer emergency brakes will come on.
the brakes can overheat and lose their braking power.
of the danger of making the trailer skid.
All of the above.
3. The best way to recognize that your trailer has started to skid is:
by recognizing tire failure.
by opening the window and feeling the front of the mirror.
by seeing it in your mirrors.
by feeling the brakes come on.
4. When coupling a tractor to a semi-trailer, after checking if the fifth-wheel is in proper position for coupling you should:
make sure the area around the vehicle is clear and the trailer wheels are chocked.
connect the electrical cord and check the air lines.
secure the vehicle.
connect the air lines to the trailer.
5. Before connecting the converter dolly to the rear trailer, make sure that:
the kingpin rests on the fifth-wheel.
the shut-off valves at the rear of the first trailer are open.
the locking jaws rest on the kingpin.
the trailer height is slightly lower than the center of the fifth-wheel.
6. What is countersteering?
Turning the steering wheel quickly the other way after steering in an emergency situation.
Locking your wheels while turning in an emergency situation.
Driving too fast for conditions.
Staying off the brake while steering to the right to avoid an accident.
7. If your vehicle has dummy couplers, why should you use them when the air lines are not connected to a trailer?
To prevent overheating.
Because if you don't, you will never build system pressure.
To prevent water and dirt from getting into the coupler and the air lines.
To prevent freezing of the washer liquid.
8. To avoid rollovers, you should drive slowly:
off ramps.
around corners.
on ramps.
All of the above.
9. To reduce the chance of rollover, you should:
place the cargo as high as possible inside the trailer.
distributed the cargo as low as possible inside the trailer.
put the lightest parts of the cargo under the heaviest parts.
None of the above.
10. If your trucks has a high center of gravity, which of the following is true for curves?
You should slow down, as your truck can roll over at the posted speed limit for the curve.
You should travel at the posted speed limit.
Reduce your speed to a crawl.
None of the above.
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DC 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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