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Coupling and Uncoupling — CDL Combination Vehicles Practice Test

Coupling and UncouplingQuestion 1 of 30

39 questions in this topic · 30 drawn at random this round

Uncoupling Step 2 — How do you ease pressure on the fifth wheel locking jaws so you can release the locking lever?

CDL Manual — Combination Vehicles

Questions are based on the official CDL manual (AAMVA model) used by state DMVs. The real CDL knowledge test is given in English — federal rules (FMCSA, 49 CFR 391.11) require English proficiency to drive commercially; our Chinese & Spanish are study aids. Some states also offer the written test in other languages (see the per-state table).

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This CDL Combination Vehicles Coupling and Uncoupling 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 Coupling and Uncoupling bank with the correct answer and an explanation. The practice quiz above draws 30 questions at random from the same bank.

  1. Why is it important to know how to couple and uncouple correctly?

    • Wrong coupling or uncoupling can be very dangerous — Correct answer
    • It is only needed to save fuel
    • It lets you skip the pre-trip inspection
    • It is required only for empty trailers

    Explanation: Wrong coupling (挂接 / acople) and uncoupling (摘挂 / desacople) can be very dangerous, so it is basic to safe operation of combination vehicles. English terms: coupling, uncoupling, combination vehicle (组合车 / vehículo combinado).

    Handbook: Coupling and Uncoupling — Why It Matters

  2. Step 1 — When inspecting the fifth wheel before coupling, what must you check about its mounting and frame?

    • It is securely mounted with no cracks in the frame — Correct answer
    • That it is painted the same color as the trailer
    • That the tires are inflated
    • Nothing — the fifth wheel needs no inspection

    Explanation: Step 1 (Inspect Fifth Wheel): check for damaged/missing parts and that the mounting to the tractor is secure with no cracks in the frame. English term: fifth wheel (第五轮 / quinta rueda).

    Handbook: Coupling and Uncoupling — Step 1 Inspect Fifth Wheel

  3. Step 1 — For proper coupling, how should the fifth wheel be tilted and what position should the jaws be in?

    • Tilted down toward the rear of the tractor with the jaws open — Correct answer
    • Tilted up toward the front with the jaws closed
    • Perfectly level with the jaws closed
    • Tilted to the left with the jaws open

    Explanation: The fifth wheel should be tilted down toward the rear of the tractor with the jaws open, and the safety unlocking handle in the automatic-lock position. English terms: fifth wheel, locking jaws (锁止钳口 / mordazas de bloqueo).

    Handbook: Coupling and Uncoupling — Step 1 Fifth Wheel Position