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Due to flooding, the Everett Driver Licensing Services Office is closed. We'll update this message when we have a reopening date. In the meantime, customers are encouraged to access our online services or visit these nearby offices: Smokey Point, Lynnwood, and Shoreline.

Practice CDL knowledge test: Question 18 of 20

The trailer hand valve (also called the trolley valve or Johnson bar) works the trailer brakes. Don't use it in driving because of the danger of making the trailer skid. The trailer hand valve should only be used when:

A There is ice and snow, to prevent skidding.
B Testing the trailer brakes after hooking up to a trailer.
C You will be parked for a short time.
A INCORRECT

The correct answer is:
Testing the trailer brakes after hooking up to a trailer.

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B CORRECT

Testing the trailer brakes after hooking up to a trailer.

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C INCORRECT

The correct answer is:
Testing the trailer brakes after hooking up to a trailer.

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