Air Brakes practice test
The test that removes the restriction on air-brake vehicles.
Air Brakes is the knowledge test for vehicles with air brake systems. It is not an endorsement — it removes a restriction. A licence issued to a driver who tests in a vehicle with air brakes carries no restriction; a driver who tests in a vehicle without air brakes gets an 'L' restriction that says they may not drive a vehicle with air brakes. Most heavy vehicles use air brakes, which is why most drivers choose to remove the restriction. The test covers the parts of an air brake system, how air pressure is built and held, the low-pressure warning, the parking and emergency brakes, spring brakes, slack adjusters, brake fade and brake balance, air loss rates, anti-lock brakes, and the pre-trip air brake check. This site practises the written test only; it never teaches anyone to operate air brakes. The full explanation for every item here is free.
Air brakes remove an 'L' restriction rather than adding an endorsement. Most drivers take it because most heavy vehicles have air brakes.
AB-001
Air brakes use the force of compressed air to:
These questions are written to the federal knowledge areas every state is required to test. They are not your state's questions — no free site has those. Your state writes its own test from its own CDL manual, and that manual is the thing to study.
All the tests
The requirement matrix on the home page computes which of the eight you need.
This site prepares for a written knowledge test. It is not driver training, it is not ELDT, and nothing on it substitutes for your state's CDL manual or a registered training provider. Air brake procedure, coupling, load securement and hazardous-materials handling are safety-critical, and this site never teaches them as something to do.
Common questions
- Why does air brakes matter if it is not an endorsement?
- Because it removes a restriction. If you test in a vehicle without air brakes, your licence carries an 'L' restriction against air-brake vehicles. Most heavy vehicles use air brakes, so most drivers take the test to remove the restriction.
- Are these questions from my state's air brakes test?
- No. These are written to the federal knowledge areas every state is required to test. Your state writes its own air brakes questions from its own manual, and that manual is the thing to study. No free site has a state's own test questions.