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Coupling and Uncoupling — CDL Doubles Triples Practice Test

Coupling and UncouplingQuestion 1 of 30

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

Once the fifth wheel latch is released, how do you get the dolly out from under the rear trailer?

CDL Manual — Doubles and Triples (§7)

Questions are based on Section 7 (Doubles and Triples) of the official CDL manual (AAMVA model). The Doubles/Triples (T) endorsement is a knowledge test only — there is no separate skills test for the endorsement itself — and it is given in ENGLISH (real test); our Chinese & Spanish are study aids to help you learn the English material. The manual also directs you to study Sections 2, 5, and 6. Federal rules (FMCSA, 49 CFR 391.11) require English proficiency to drive commercially.

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This CDL Doubles Triples 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 Doubles Triples 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 does a doubles/triples driver need to know how to couple and uncouple correctly?

    • Because it is basic to safe operation and doing it wrong can be very dangerous — Correct answer
    • Because it lets you skip the pre-trip inspection
    • Because it is only needed when hauling hazardous materials
    • Because the law allows uncoupling only on public roads

    Explanation: Knowing how to couple and uncouple correctly is basic to safe operation of doubles and triples; wrong coupling or uncoupling can be very dangerous. English term: coupling (挂接 / acoplamiento).

    Handbook: Section 7: Doubles and Triples — Coupling and Uncoupling

  2. To secure a second trailer that does NOT have spring brakes, after driving the tractor close and connecting the emergency line, what do you do next?

    • Charge the trailer air tank, then disconnect the emergency line to set the trailer emergency brakes — Correct answer
    • Leave the emergency line connected and drive away immediately
    • Open the air tank petcock to drain the trailer air tank
    • Release the service line and raise the landing gear

    Explanation: Drive close, connect the emergency line, charge the trailer air tank, then disconnect the emergency line — this sets the trailer emergency brakes (if the slack adjusters are correctly adjusted). English term: emergency line (应急管路 / línea de emergencia).

    Handbook: Section 7: Doubles and Triples — Securing the Second Trailer

  3. What should you do if you have any doubt about the second trailer's brakes?

    • Chock the wheels — Correct answer
    • Drive faster so momentum carries the load
    • Disconnect the air lines and leave the trailer free
    • Ignore it because the tractor brakes hold everything

    Explanation: Chock the wheels if you have any doubt about the second trailer's brakes. English term: chock the wheels (用三角木垫轮 / calzar las ruedas).

    Handbook: Section 7: Doubles and Triples — Securing the Second Trailer