Your trailer breaks away on the highway. What keeps air in the tractor's brakes?
Right! The tractor protection valve keeps air in the tractor if the trailer breaks away or leaks badly. 📖 p. 6-5
From Section 6 of the North Carolina Commercial Driver License Manual
North Carolina CDL Combination Vehicles Practice Test
Who takes it: Class A.
Tractor-trailers and trucks pulling a heavy trailer. 20 questions, 16 right to pass (80%).
Practice Combination Vehicles
- 10questions a round
- 1manual section
Take the Combination Vehicles test
- 20questions
- 16correct to pass
- –no test taken yet
A Combination Vehicles question to try
Tap an answer to see if you’re right, and the page
Where it is in the North Carolina Commercial Driver License Manual
Your score on each part fills in as you study.
- Manual section 6
- Combination vehiclesNot practiced yetp. 6-1 to 6-11
North Carolina answers about this test
Practice material, not the official test: check every answer in your state's current handbook. Disclaimer · How the rounds work · DMV
All North Carolina CDL tests
- General Knowledge
- Combination VehiclesYou're here
- Air Brakes
- Doubles and Triples
- Passenger
- School Bus
- Tank Vehicles
- Hazardous Materials
- Which tests do you need?Pick what you'll drive and get your North Carolina CDL plan, in order.