CDL Key Vocabulary
Essential terms and definitions you must know before exam day.
Key Vocabulary
HOS
Hours of Service — DOT regulations limiting driving and on-duty time.
Pre-trip inspection
Mandatory vehicle safety check before each trip.
Fifth wheel
The coupling device on a tractor that connects to the trailer's kingpin.
Placard
Diamond-shaped signs on trucks carrying hazardous materials identifying the hazard class.
Vocabulary Study Tips
- 1.Your state's CDL manual is the only source you need — read it cover to cover.
- 2.Hours of Service rules are complex — make a cheat sheet with the key numbers (11h driving, 14h window, 10h reset, 70h in 8 days).
- 3.Air brakes endorsement: know the three brake tests (static, governor, low air warning).
- 4.For HazMat: memorize the 9 hazard classes and their placard requirements.