District of Columbia DMV CDL Combination Quick Practice Test

District of Columbia DMV CDL Combination Quick Practice Test For 2024

CDL Class A, B or C. Complete CDL driver training course. All the questions in this test are from the official DMV written exam. You can use our free online tests to evaluate how likely you are to pass the official DMV test. Or you can just cut to the chase and increase your chances of passing by upgrading to Premium Membership and unlock official DMV tests. In addition, you will also receive a master cheat sheet which contains all your state’s DMV questions and answers. Premium membership also unlocks a smart tracker which keeps an inventory of all incorrectly answered questions for easy, fast and effective revision. Practice with our free tests or hit Upgrade button below for premium access and increase your chances of passing your DMV written exam.

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Quick Facts:

Number of Questions – 20

Passing Percentage – 80%

Test Type – Free Test

1. Fully-loaded rigs:

Are less likely to roll over than empty rigs.
Are more likely to roll over than empty rigs.
Are just as likely to roll over as empty rigs.
Should not be driven.

2. If colors are being used to distinguish glad hands, which color is used for service lines?

Orange
Yellow
Green
Blue

3. Rearward amplification refers to:

The amount of noise projected to the rear of a vehicle.
The cause of the "crack-the-whip" effect.
The number of trailers that can be pulled by a tractor.

4. What is a tractor protection valve?

A valve to keep air in the brake system should there be a bad leak
A valve that prevents the truck from being stolen
A valve that prevents the driver from going too fast
A valve that prevents the trailer from accidentally being released

5. A trolley valve:

Should be used while driving.
Should only be used to test trailer brakes.
Should be used when parking uphill.

6. How many air lines does a combination vehicle have?

One
Two
Three
Four

7. Starting in which year were newly manufactured trailers required to have ABS?

1972
1987
1998
2004

8. When the wheels of a trailer lock up:

The trailer will stay straight.
The trailer tends to swing around.
The cab will swing, but the trailer will stay straight.
They will likely go flat.

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