Skip to content

The CDL Air Brake Restriction

The air brake restriction blocks a CDL holder from driving any commercial motor vehicle equipped with air brakes. Under 49 CFR 383.95, a state must place this restriction on a CLP or CDL if the applicant either fails the air brake portion of the knowledge test, or takes the skills test in a vehicle that doesn't have air brakes. The restriction's definition of "air brakes" is broad: it covers any braking system that operates fully or partially on the air brake principle, not just a traditional air-over-hydraulic or full air system.

Why it exists

Air brakes have their own failure modes, like a slow air leak, a dropping pressure gauge, or a parking brake that engages automatically at low pressure, that a driver trained only on hydraulic brakes wouldn't necessarily know to watch for. The restriction keeps someone who hasn't passed the air brake knowledge test, or tested in an air-braked vehicle, from driving one on the road.

How to avoid or remove it

To avoid the restriction in the first place, pass the air brake component of the knowledge test and take your skills test in a vehicle equipped with air brakes. If you already have the restriction, 49 CFR 383.135(b)(7) governs removing it: you don't have to retake the complete skills test, since the State may give a modified skills test that just confirms you can safely operate full air brakes (or air-over-hydraulic brakes). What's required is passing the air brake knowledge test and successfully performing the air brake pre-trip inspection. OurAir Brakes practice testcovers the 25 questions in the knowledge area that test actually draws on, each with a written explanation and a citation to the regulation behind it, and ourAir Brakes simulated testscores you against the federal 80% passing standard.

What this doesn't tell you

Your state DMV handles the actual paperwork and schedules whatever modified skills test it offers under 383.135(b)(7); exactly how that's booked and what it costs varies by state. Confirm the process with your state's licensing agency.

Start practicing Air Brakes

Frequently asked questions

What triggers a CDL air brake restriction?

A state must place the restriction on your CLP or CDL if you fail the air brake portion of the knowledge test, or if you take your skills test in a vehicle without air brakes, under 49 CFR 383.95(a). It blocks you from driving any vehicle equipped with air brakes.

How do I remove an air brake restriction?

Your state may give you a modified skills test instead of the complete test, under 49 CFR 383.135(b)(7), confirming you can safely operate air brakes. You still need to pass the air brake knowledge test and the air brake pre-trip inspection; you just don't have to retake the whole skills test over again.

What counts as 'air brakes' for this restriction?

It depends on which test you took. Testing in a vehicle with no air brakes at all triggers the broad restriction under 49 CFR 383.95(a), blocking any system that works fully or partially on the air brake principle, including air-over-hydraulic. Testing in an air-over-hydraulic vehicle instead triggers a narrower restriction under 383.95(b), blocking only full air brake systems.