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Doubles & Triples Practice Question 27

TDoubles & Triples · Question 27

When you couple to a second trailer using a converter dolly, the trailer brakes for the second trailer get air supply through:

• AA separate compressor
• BThe dolly's air lines connected from the first trailer's rear glad hands
• CThe radio antenna
• DIndependent batteries

Correct answer: B. The dolly's air lines connected from the first trailer's rear glad hands

Why: Air flows from tractor → first trailer → rear glad hands of first trailer → dolly air lines → second trailer. Each handoff must be sealed and tested.

How this question fits the Doubles/Triples test

Each additional articulation point multiplies rearward amplification. A driver pulling triples must steer earlier, brake sooner, and inspect twice as much equipment as a single-trailer driver.

Study technique for this topic

Learn the correct trailer placement order by weight, the procedure for converting a single to a double, and the special inspection items unique to converter dollies and pintle hook assemblies.

Related Doubles/Triples practice questions

• Q19. The rear trailer in a triple can swing how much more than the tractor on a quick steering …
• Q33. A converter dolly that drops its tongue when uncoupled can:
• Q46. The converter dolly tongue is:
• Q59. Mirror checks for doubles/triples should be:
• Q12. When braking a doubles or triples combination, you should:

Continue your CDL preparation

The Doubles & Triples portion of the CDL knowledge exam covers more than this single question. Use this site's full Doubles & Triples bank to drill every topic, then test yourself with one of our state-specific practice sets to confirm you are ready for the actual DMV exam in your state. Always check your state's CDL handbook for any local addenda before the test day.

If you are still building your overall CDL foundation, start with the General Knowledge bank — every CDL applicant must pass it — and then work outward to the endorsements you plan to add.