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Drivers who want to drive combination vehicles must pass the combination vehicles test. The Colorado 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 Colorado CDL Manual. Take this practice test now to prepare for the actual CO CDL combination test!
1. ABS:
should only be used on dry roads.
is an addition to your normal brakes.
allows you to brake harder.
replaces your normal brakes.
2. In combination vehicles with air brakes, the trailer air supply control:
is used to control the tractor protection valve.
supplies air to the trailer air tanks.
is used to keep the trailer behind the tractor.
is a coupling devices used to connect the service and emergency air-lines from the tractor to the trailer.
3. When checking the air and electric lines to the trailer, be sure that the air lines are properly connected to the gland hands, and are:
secured with enough air leaks for turns.
properly greased.
secured with enough slack for turns.
None of the above.
4. Empty trucks:
have better traction than fully-loaded trucks.
may have poor traction.
require shorter stopping distances than fully-loaded trucks.
None of the above.
5. On a tractor-trailer equipped with a trailer brake hand valve, the hand valve can be used to:
reduce the chance of the front wheels skidding.
hold compressed air.
prevent movement of cargo.
keep from rolling back.
6. The center of gravity of a trailer should be:
as high as possible.
as low as possible.
at the front of the trailer.
at the rear of the trailer.
7. The tractor protection valve:
works the trailer brakes.
controls the emergency brakes on combination vehicles.
keeps air in the tractor brake system should the trailer break away or develop a bad leak.
supplies air to the trailer air tanks.
8. Passive railroad crossings:
do not have traffic control devices.
have at least one traffic control device.
usually have a person directing traffic.
should never be crossed using a CMV.
9. Placards must be at least _____ inches square.
10. Most heavy trucks with manual transmissions require ____ to change gears.
triple clutching
double clutching
single clutching
None of the above.
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CO CDL Combination Test

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