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CDL · Coupling and Uncoupling

After coupling a doubles combination, what verification should be performed before driving?

Reviewed by Jordan Morley, Editorial Lead at 247SimpleTests. Written by the 247SimpleTests Editorial Team from the official source material cited on every question.

Correct answer

Tug tests on each fifth wheel coupling, visual inspection of pintle hook and safety chains, verification of all air and electrical connections, and brake testing for all trailers

  1. A Just visual inspection from the cab
  2. B Tug tests on each fifth wheel coupling, visual inspection of pintle hook and safety chains, verification of all air and electrical connections, and brake testing for all trailers
  3. C Driving briefly to test
  4. D Just checking the tractor's gauges

Why this is the answer

Verification of a complete doubles coupling involves multiple checks: (1) tug test on the tractor-to-lead-trailer fifth wheel coupling; (2) tug test on the dolly-to-rear-trailer fifth wheel coupling (pull against each kingpin to verify engagement); (3) visual inspection of the pintle hook with safety chains/cables; (4) air and electrical line connections at every coupling point checked for proper seal and operation; (5) brake test using the trailer hand valve and the foot brake to verify all trailers brake correctly; (6) low-pressure warning and spring brake tests as on any combination. Skipping any check risks a catastrophic failure on the road.
Source: FMCSA CDL Manual 7.2.4 Coupling Verification

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About this topic: Coupling and Uncoupling

Coupling and uncoupling doubles and triples adds the converter dolly and the pintle hook to the usual fifth-wheel procedure, and the order matters — heaviest trailer first, lightest last. These questions walk through the steps and the checks that confirm a secure connection. This is one of 16 Doubles and Triples questions on coupling and uncoupling, each with a full explanation on a single study page.

New to this exam? Our CDL exam guide explains the format, scoring, and how to prepare.

Related questions

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What is a 'converter dolly' in a doubles combination?

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When uncoupling a converter dolly, what is the safe sequence?

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When inspecting the pintle hook on a converter dolly before coupling, what should you verify?

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