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Doubles triples practice questions

25 questions from the cdl endorsements practice test.

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Doubles triples practice test

10 questions, graded as you go, with the reason for every answer. No sign-up.

What this covers

Sample questions

Which combination has the greatest rearward amplification?

  1. A set of doubles
  2. A tractor-semitrailer
  3. A straight truck
  4. A set of triples
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D. A set of triples

Rearward amplification grows with the number of trailers and articulation points, so triples have the most. A straight truck has none because it has no trailer.

Reference: AAMVA CDL Manual, Section 6.1 and 7.1

Compared with a five-axle tractor-semitrailer, a set of doubles needs:

  1. Less following distance because it has more brakes
  2. The same space, since the gross weight is similar
  3. More following distance and larger gaps in traffic
  4. More space only when the trailers are fully loaded
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C. More following distance and larger gaps in traffic

Doubles and triples are longer and cannot be turned or stopped suddenly, so they need more room ahead and bigger gaps to enter or cross traffic. Extra axles do not make up for the extra length and instability.

Reference: AAMVA CDL Manual, Section 7.1

Why are doubles and triples more likely to skid or lose traction in bad weather?

  1. They have fewer brakes than a single trailer would have
  2. They carry less weight on each trailer axle
  3. They must run at lower tire pressures
  4. They have more length and more dead axles to pull
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D. They have more length and more dead axles to pull

The drive axles must pull more length and more non-driven (dead) axles, so traction runs out sooner on slick roads. Every axle still has brakes.

Reference: AAMVA CDL Manual, Section 7.1

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