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Doubles & Triples Practice Question 9

TDoubles & Triples · Question 9

Air supply lines for the rear trailer pass through:

• AThe first trailer's frame
• BEach preceding trailer/dolly via additional glad hand connections
• CThe tractor cab
• DThe exhaust pipe

Correct answer: B. Each preceding trailer/dolly via additional glad hand connections

Why: Air must travel through every unit. Each trailer/dolly has its own glad hand pair, and one bad connection anywhere can disable rear brakes.

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

• Q52. When triples are not allowed on a route:
• Q5. The pintle hook is:
• Q19. The rear trailer in a triple can swing how much more than the tractor on a quick steering …
• Q32. A driver of doubles/triples should keep a minimum following distance of:
• Q45. When pulling out from a stop sign with doubles, 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.