Practice test

CDL Practice Exam 12

Advanced CDL practice exam 12 on air brake system diagnostics, restriction codes, and regulatory edge cases. 25 questions with full explanations.

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These questions are for study practice only and are not official exam questions.

Question 1

1

During a pre-trip inspection, a driver runs the engine and lets air pressure build to governor cutout. What is the driver checking by then applying the brakes and watching for pressure loss?

Question 2

2

With the engine off and a fully charged air system, a driver applies and holds the foot brake for one minute. For a single vehicle, what is the maximum allowable air pressure drop during this test?

Question 3

3

What does ABS (Antilock Braking System) do on a commercial motor vehicle?

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