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CDL: Combination Vehicles

Required for Class A: coupling, off-tracking, jackknife, trailer swing and air-line / fifth-wheel checks.

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What this section covers

Combination Vehicles is the Class A knowledge test — typically 20 questions, 80%. You sit it if you will pull a trailer of 10,001 lb or more behind a 26,001+ lb power unit.

What this section is for:

  • Off-tracking and wide turns
  • Jackknife vs trailer swing vs rearward amplification
  • Fifth wheel, kingpin, locking jaws, glad hands
  • Service line vs emergency (supply) line
  • Why you never park with the trailer hand valve

Class B drivers do not take this test. See Class A vs Class B. Doubles/triples is a separate T endorsement on top of this.

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