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CDL · Coupling and Uncoupling

After coupling, how do you verify the converter dolly's pintle hook and the trailer connections are secure?

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

Visually confirm the pintle hook is fully latched (not just resting), the safety chains are secured, the fifth wheel shows no gap with the trailer, and the kingpin is locked, then test by gently pulling against the connection

  1. A Visually confirm the pintle hook is fully latched (not just resting), the safety chains are secured, the fifth wheel shows no gap with the trailer, and the kingpin is locked, then test by gently pulling against the connection
  2. B Only check the air lines
  3. C Assume they are fine if they look connected
  4. D Skip checks to save time

Why this is the answer

A doubles or triples coupling has several connection points that must each be verified. The pintle hook on the trailer ahead must be fully closed and latched around the dolly's eye, not merely resting on it, and the safety chains must be secured. At the fifth wheel, there must be no space between the upper and lower fifth wheel or between the trailer and the fifth wheel, and the locking jaws must be closed around the kingpin. The driver should also connect and check the air and electric lines. A gentle pull test against the locked connection confirms it will hold. A missed connection can let a trailer separate at speed — a catastrophic failure.
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.

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