Inspecting a Combination Vehicle — CDL Combination Vehicles Practice Test

This CDL Combination Vehicles Inspecting a Combination Vehicle practice set has 39 practice questions based on the official exam materials, each with an instant explanation. You need 80% on the real CDL Combination Vehicles knowledge test to pass.

Sample questions

Three questions from the Inspecting a Combination Vehicle bank with the correct answer and an explanation. The practice quiz above draws 30 questions at random from the same bank.

1. How do you inspect a combination vehicle compared with a single vehicle?

   • Use the same seven-step procedure, but inspect additional and new items unique to the combination — Correct answer
   • Skip the seven-step procedure because the trailer covers most parts
   • Inspect only the trailer, since the tractor was checked at the depot
   • Use a completely different three-step procedure made for trailers

   Explanation: Use the same seven-step inspection procedure described in Section 2, but there are MORE things to inspect on a combination vehicle, plus some NEW items (the coupling system, lines, and combination brake check). English term: combination vehicle（组合车 / vehículo combinado）.

   Handbook: Inspecting a Combination Vehicle — Walk-around Inspection

2. When checking the lower fifth wheel, how should it be mounted?

   • Securely mounted to the tractor frame, with no cracks or missing parts — Correct answer
   • Loosely bolted so it can pivot freely in any direction
   • Held on only by the weight of the trailer resting on it
   • Welded directly to the trailer apron

   Explanation: The lower fifth wheel must be securely mounted to the tractor frame. A loose or cracked mounting can let the trailer come loose. English term: fifth wheel（第五轮 / quinta rueda）.

   Handbook: Inspecting a Combination Vehicle — Lower Fifth Wheel

3. What must you check about the parts of the lower fifth wheel?

   • That there are no missing or damaged parts — Correct answer
   • That all parts are painted the same color
   • That the parts are warm to the touch
   • Only that the manufacturer's label is present

   Explanation: Check the lower fifth wheel for no missing or damaged parts — any defect in the coupling can be dangerous. English term: fifth wheel（第五轮 / quinta rueda）.

   Handbook: Inspecting a Combination Vehicle — Lower Fifth Wheel