Traffic Laws

Study questions with answers

3 sample Traffic Laws questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.

1. 1. For a combination vehicle, what is the most air pressure that may be lost in one minute during the leakage test?

   Correct answer: 4 psi

   A combination vehicle may lose no more than four psi in one minute with the brakes held; anything more is a failing leak rate.

   Source: Wisconsin Commercial Driver's Manual (BDS356), Section 5.3.3 - Test air leakage rate

2. 2. How can you find out whether your vehicle was built with ABS?

   Correct answer: By checking the certification label's build date, or the yellow ABS lamps

   Read the build date printed on the vehicle's certification label, and watch for the yellow ABS lamps that equipped units carry.

   Source: Wisconsin Commercial Driver's Manual (BDS356), Section 5.1.16 - Antilock braking systems (ABS)

3. 3. With the foot brake fully applied and held for one minute on a single vehicle, how much air loss is too much?

   Correct answer: More than 3 psi in one minute

   For a single vehicle, a drop of more than three psi over that minute means the leak rate is out of limits and must be fixed.

   Source: Wisconsin Commercial Driver's Manual (BDS356), Section 5.3.3 - Test air leakage rate