Practice question

What does the tractor protection valve do?

  1. Protects the tractor from being stolen
  2. Protects the tractor from exceeding a set speed
  3. Keeps air in the braking system, should the trailer break away or develop a leak
  4. Ensures oil adequately lubricates the engine

Answer: C — Keeps air in the braking system, should the trailer break away or develop a leak

The correct answer is shown above. Try the full quiz for additional practice.

Practice more: Indiana CDL Combination Test 2 →