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Drivers who want to drive combination vehicles must pass the combination vehicles test. The Kentucky 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 Kentucky CDL Manual. Take this practice test now to prepare for the actual KY CDL combination test!
1. In a vehicle with a dual air brake system:
each system has its own air tanks.
both systems typically operate the regular brakes on the rear axle.
one system supplies air to the trailer.
All of the above.
2. A bridge formula permits less maximum axle weight for axles that:
are further apart than normal
have a high center of gravity
are closer together
have poor weight balance
3. Dual tires:
should come in contact with each other whenever possible.
are dangerous.
should always come in contact with each other.
should not come in contact with each other.
4. If you unlock the pintle hook with the dolly still under the rear trailer:
your vehicle might roll away.
the brakes could be damaged by the combined forces of the springs and the air pressure.
steam and boiling water can spray under pressure.
the dolly tow bar may fly up.
5. Which of the following statements about off-tracking is true?
When a vehicle goes around a corner, the rear wheels follow the same path as the front wheels.
Longer vehicles off-track less.
If there is more than one trailer, the rear wheels of the last trailer will off-track the most.
None of the above.
6. Axle weight is:
the maximum safe weight your tires can carry at a specified pressure.
the weight of all the axles added together.
the value specified by the manufacturer as the loaded weight of one axle.
the weight transmitted to the ground by one axle or one set of axles.
7. You are driving on a steep downgrade in the proper low gear. Your "safe" speed is 40 mph. When your speed reaches 40 mph, you should:
maintain your current speed, and apply the brakes when you reach 50 mph to gradually reduce your speed to 40 mph.
increase your speed to approximately 45 mph, and then apply release the brakes.
apply the brakes to quickly reduce your speed to 25 mph, and then release the brakes.
apply the brakes to gradually reduce your speed to 35 mph, and then release the brakes.
8. If the safety relief valve in the air brake system releases air:
this will supply more power to the brakes.
the valve is fully operational.
something is wrong.
this will supply more power to the drive wheels.
9. When driving on slippery surfaces, you should:
make turns as quickly as possible.
change lanes often.
not pass slower vehicles unless necessary.
All of the above.
10. Headlights:
can blind other drivers.
should be out of adjustment.
must be turned on a half hour before sunset to a half hour after sunrise.
should not be used when driving at night.
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CDL Combination Test (KY)

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