Combination Vehicles · Question #179

When uncoupling, after lowering the landing gear, the next step is:

A. Disconnect air lines and electrical, secure them, then release fifth wheel
B. Pull away immediately
C. Set the brake only
D. Disconnect kingpin manually

Correct answer: A. Disconnect air lines and electrical, secure them, then release fifth wheel
Explanation: Lines first, then release fifth wheel, then drive forward slowly.

Why this question matters on the Combination Vehicles exam

This question is one of the 65 we have for the Combination Vehicles CDL knowledge test. The official AAMVA Commercial Driver License Manual chapter on Combination Vehicles covers exactly this topic, and most state DMV exams pull from the same chapter. Memorizing the right answer is fine for passing, but understanding the underlying rule is what keeps you safe on the road and out of trouble with FMCSA inspectors.

If this topic gave you trouble, take the full Combination Vehicles practice test to drill it across all the related questions. We recommend reading every explanation, even on the questions you got right, because the manual phrasing in the explanation often shows up word-for-word on the real exam.

Take the full Combination Vehicles practice test →