CDL (Commercial Driver)
CDL Air Brakes Practice Test 3
Free — no payment neededPractice betaLevel: Mixed
20 original CDL Air Brakes questions based on the federal motor carrier safety rules (49 CFR). Practice test, not affiliated with any government agency. Practice beta.
Created by AI
Practice test, not affiliated with any government agency. Original questions written from public sources, checked by a second AI reviewer and automated checks. Rules change; confirm with the official handbook. Available in 2 languages (translations are machine-made and checked automatically).
Before you start
- Questions
- 20 multiple-choice questions, one at a time
- Time
- About 12 minutes. Untimed — take as long as you need.
- Pass mark
- 16 out of 20 correct (80%)
- Feedback
- Your score, the correct answers and short explanations when you finish
- Account
- Not needed. Your answers stay in this browser.
What this test covers
Inspecting air brakesUsing air brakesAir brake system parts
Preview the first question
Under federal rules, the low air warning must come on before tank pressure drops below what?
- 55 psi, or half the governor cut-out pressure if lower
- The pressure set by the driver before the trip
- 20 psi on the secondary tank only, at any governor setting
- 100 psi in every vehicle
Answers are revealed on the results page after you finish.