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CDL · Pulling Doubles and Triples

On a long downgrade with a doubles or triples combination, what braking approach keeps the vehicle under control?

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

Select a low gear before the descent and use the engine and a steady, controlled braking technique to keep speed in check, avoiding overheating the brakes through constant light application

  1. A Ride the brakes continuously all the way down
  2. B Select a low gear before the descent and use the engine and a steady, controlled braking technique to keep speed in check, avoiding overheating the brakes through constant light application
  3. C Brake only at the bottom
  4. D Coast in neutral to save fuel

Why this is the answer

Long downgrades are managed primarily with the proper low gear selected before the descent, letting engine braking help control speed, combined with a controlled braking technique that keeps the brakes from overheating. Continuously riding the brakes causes them to overheat and fade, which is extremely dangerous with a heavy, long combination. Coasting in neutral is illegal and unsafe. The driver chooses a safe speed for the grade, uses the gearing to hold it, and applies the brakes firmly enough to control speed without keeping constant light pressure that builds heat. With multiple trailers, a runaway on a downgrade would be nearly impossible to recover, so preparation before the hill is critical.
Source: FMCSA CDL Manual 7.1.10 Downgrade Braking

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About this topic: Pulling Doubles and Triples

Pulling doubles and triples means managing the most unstable combination on the road: the rear trailer whips, rolls and jackknifes more easily, following distance must grow, and the sequence of air-line and brake checks is longer. These questions cover the handling rules specific to multiple trailers. This is one of 29 Doubles and Triples questions on pulling doubles and triples, 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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