How to Get Your Airbrake Endorsement on Your CDL

What the airbrake endorsement is and why you need it

The airbrake endorsement, often called the "L" restriction removal, is a notation on your Commercial Driver's License that shows you can operate trucks and buses with air brake systems. If you hold a CDL without this endorsement, you have an "L" restriction printed on your license — which means you are legally prohibited from driving any vehicle that uses air brakes, even if you are otherwise may have access to to drive that class of truck.

Most heavy trucks and all large buses use air brakes instead of hydraulic brakes. If your job requires you to drive these vehicles, you must have the airbrake endorsement. Without it, you cannot legally operate the vehicle, and your employer cannot legally assign you to drive it. The endorsement is not optional for most commercial driving roles — it is a legal requirement tied to the vehicle itself, not the driver's choice.

Key Takeaways

You must pass a written knowledge test about air brake systems and then pass a skills test in a vehicle with air brakes to remove the "L" restriction from your CDL.
The written test covers how air brakes work, maintenance, inspection, and safe operation — you study from your state's CDL manual and take the test at your state's licensing office.
The skills test (also called the road test or driving exam) must be performed in an actual truck or bus with a functioning air brake system; you cannot use a vehicle with air brakes disabled.
You can take the written test and skills test on the same day or on separate days, depending on your state's rules and your own readiness.
The cost varies by state but typically ranges from $10 to $50 for the written test and $0 to $100 for the skills test, though some states bundle them into your CDL renewal fee.

Step-by-step process to earn the airbrake endorsement

Step 1: Study the air brake section of your state's CDL manual. Your state's Department of Motor Vehicles publishes a free CDL manual (usually available online and in print at the licensing office). The air brake section covers system components, how they work, pre-trip inspection procedures, and common failures. Read this section thoroughly — the written test draws directly from it.

Step 2: Schedule and pass the written knowledge test. Visit your state's DMV or licensing office and request the air brake knowledge test. You will answer multiple-choice questions about air brake operation, maintenance, and safety. The number of questions and passing score vary by state, but typically you need to answer 70 to 80 percent correctly. You can usually take this test the same day you request it, though some offices require an appointment.

Step 3: Arrange a vehicle with air brakes for your skills test. You must perform your road test in an actual commercial vehicle equipped with a functioning air brake system. Many CDL training schools provide vehicles for this purpose. If you are training independently, you may need to borrow or rent a truck from your employer or a training facility. The vehicle must be the same class as the CDL you hold (Class A, B, or C).

Step 4: Schedule and pass the skills test. Contact your state's DMV to book a road test appointment with an examiner. During the test, the examiner will observe your pre-trip inspection (including air brake checks), your operation of the vehicle, and your ability to handle the air brake system safely. The test typically lasts 30 to 45 minutes. You must demonstrate safe operation and proper use of the air brakes under various conditions.

What the written test covers

The air brake written test focuses on practical knowledge you need to operate and maintain the system safely. You will be tested on how air compressors, reservoirs, and brake chambers work together; how to inspect air brake components during your pre-trip walk-around; warning signs of air brake failure; and how to respond if your brakes fail while driving.

The test also covers the difference between service brakes and parking brakes, how to use the brake pedal and hand valve correctly, and the dangers of moisture and contamination in the air system. Some states include questions about dual air brake systems and how they protect you if one system fails. Study the exact section in your state's manual — the test questions come directly from that material, and you will not face surprises if you have read it carefully.

What the skills test requires

The road test has three main parts: the pre-trip inspection, the basic vehicle control test, and the road driving test. During the pre-trip inspection, the examiner will ask you to walk around the vehicle and point out and explain the air brake components — the air compressor, brake lines, slack adjusters, brake chambers, and safety devices. You must show you know where these parts are and what they do.

In the basic vehicle control portion, you will perform maneuvers like backing, turning, and parking while the examiner watches for smooth, controlled operation of the air brakes. During the road test, you will drive on public roads or a closed course, demonstrating normal braking, emergency braking, and proper use of the service and parking brakes. The examiner is watching for safe operation, awareness of the air brake system's response time, and your ability to control the vehicle in different conditions.

Timing and scheduling considerations

You can take the written test and skills test in either order, and on the same day or different days. Many drivers take the written test first to confirm their knowledge, then schedule the skills test once they feel ready and have access to a suitable vehicle. Some states allow you to take both tests in one visit if you pass the written test and a vehicle is available.

Wait times for skills test appointments vary widely by state and season. In busy periods, you may wait two to four weeks for an appointment. Plan ahead if you have a job start date or important date. Some states offer expedited testing or have multiple examiners available; call your local DMV to ask about current wait times before you schedule the written test.

Cost and fees

The cost of the airbrake endorsement varies by state. The written test typically costs $10 to $30, and the skills test costs $0 to $100, depending on whether your state charges separately or includes it in your CDL renewal fee. A few states charge nothing for either test if you are renewing your CDL at the same time. Some states bundle the airbrake test into a larger CDL renewal fee.

Check your state's DMV website or call your local licensing office to confirm the exact fees before you go in. If you fail the skills test, you usually pay a retest fee (often $25 to $50) to schedule another attempt. There is no limit to how many times you can retake the test, but each attempt costs money and requires scheduling a new appointment.

What happens after you pass

Once you pass both the written and skills tests, the examiner will process your endorsement at the licensing office. Your new CDL will be printed without the "L" restriction, meaning you are now legally permitted to operate any commercial vehicle with air brakes in your licensed class. The new license is usually ready within a few days to a week, depending on your state's processing speed.

If you are renewing your CDL soon, you may be able to add the airbrake endorsement to your renewal process at the same time, which can save you a trip to the DMV. Ask the licensing office whether you can combine these tasks when you call to schedule your tests.

Frequently Asked Questions

Can I take the written test without having a vehicle lined up for the skills test?

Yes. Many drivers take the written test first to confirm they understand the material, then arrange a vehicle and schedule the skills test later. There is no rule requiring you to do both on the same day or in a specific order. However, once you pass the written test, you will want to schedule the skills test within a reasonable time while the material is fresh in your mind.

What if I fail the skills test?

You can retake it. There is no limit to the number of attempts. You will need to pay the retest fee (typically $25 to $50), schedule a new appointment, and arrange the vehicle again. Many drivers use the feedback from the examiner to practice specific maneuvers before their next attempt.

Do I need to attend a CDL training school to get the airbrake endorsement?

No. You can study the manual on your own, take the written test at the DMV, and arrange your own vehicle for the skills test. However, many drivers find that a CDL training school or a few hours of professional instruction help them pass the skills test on the first attempt, which saves time and retest fees.

Can I use a vehicle with air brakes that are not fully functional for the skills test?

No. The vehicle must have a fully functioning air brake system. The examiner will test the brakes during the pre-trip inspection and will not allow the test to proceed if the system is not working properly. This is a safety requirement, not a technicality.

How long is the airbrake endorsement valid?

The endorsement is valid for as long as your CDL is valid. When you renew your CDL, the airbrake endorsement renews with it. You do not need to retake the test unless your state requires periodic recertification (which is rare) or unless your license is suspended or revoked and you have to reapply.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.