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Drivers who want to drive combination vehicles must pass the combination vehicles test. The Alabama 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 Alabama CDL Manual. Take this practice test now to prepare for the actual AL CDL combination test!
1. Which of the following is NOT part of testing the tractor protection valve?
Pulling forward slowly, then applying the trailer brakes.
Stepping on and off the brake pedal several times to reduce the air pressure in the tanks.
Charging the trailer air brake system.
Shutting off the engine.
2. _________ can make vehicle handling unsafe.
Dry roads
Poor weight balance
Poor ventilation
3. Glad hands are:
coupling devices.
warning devices.
electronic devices.
securement devices.
4. If your cargo only fills one-third of the length of your trailer, make sure your cargo is:
loaded so there is a high center of gravity.
piled up high with heavy cargo on top.
to one side and as close to the ground as possible.
centered and spread out as much as possible.
5. In vehicles with air brakes, the tractor protection valve:
carries air, which is controlled by the trailer hand brake or the foot brake.
provides the air pressure used to operate trailer brakes.
keeps air in the tractor or truck brake system.
is used to connect the service and emergency air lines from the truck/tractor to the trailer.
6. What is the emergency air line for?
It controls the front brakes of the tractor in case of an emergency.
It tells you the amount of brake pressure you need to stop the vehicle.
It supplies air to the trailer air tanks, and controls the emergency brakes on combination vehicles.
All of the above.
7. If you smell exhaust fumes in the cab, you should:
open the windows.
wait for the next stop, then inspect your vehicle.
remember to conduct a post-trip inspection.
stop immediately.
8. Which of the following is NOT part of checking the sliding fifth-wheel?
Checking that the slide is not damaged or parts are missing
Checking that all locking pins are present and locked in place
Checking that it is properly greased
Testing the tractor protection valve
9. When the wheels of a trailer lock up:
ABS will increase stopping power.
the trailer will tend to swing around.
the vehicle will gradually come to a complete stop.
All of the above.
10. Over-length loads:
require special transit permits.
require special driving care.
may require special equipment such as "wide load" or flags.
All of the above.
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CDL Combination Test (AL)

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