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CDL · Inspection

Why must the safety chains (or cables) between a converter dolly and the trailer ahead be inspected and properly secured?

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

Because if the pintle hook connection fails, the safety chains are the backup that keeps the dolly and rear trailer attached, so they must be in good condition and correctly secured with no excessive slack

  1. A They are decorative
  2. B Safety chains are optional
  3. C Because if the pintle hook connection fails, the safety chains are the backup that keeps the dolly and rear trailer attached, so they must be in good condition and correctly secured with no excessive slack
  4. D They are only for parking

Why this is the answer

Safety chains (or cables) provide a critical backup connection between the converter dolly's drawbar and the trailer ahead. If the pintle hook were to come open or fail, the chains keep the dolly and the trailer it carries from breaking completely away from the combination, helping the driver bring things to a controlled stop rather than losing a trailer at speed. During inspection the driver checks that the chains are not worn, cracked, or stretched, and that they are correctly attached with the proper amount of slack — enough to allow turning but not so much that they drag or fail to hold. Damaged or improperly secured safety chains must be corrected before the combination is driven.
Source: FMCSA CDL Manual 7.3.3 Pintle Hook and Safety Chains

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About this topic: Inspection

Air brake inspection is its own structured procedure: build-up, leakage rate, low-air warning, and spring-brake activation must all check out before you drive. This is one of 15 Doubles and Triples questions on inspection, each with a full explanation on a single study page.

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