What an air brake endorsement is and why you need it
An air brake endorsement is a notation on your Class B commercial driver's license that shows you have been tested on the operation and maintenance of air brake systems. If you drive a vehicle with air brakes — including many buses, box trucks, and dump trucks — most states require this endorsement before you can legally operate that vehicle for commercial purposes.
Without the endorsement, you can still drive a Class B vehicle with air brakes, but only if you have an air brake restriction on your license, which limits you to vehicles with hydraulic brakes only. Getting the endorsement removes that restriction and opens up more job opportunities in commercial driving.
The endorsement itself does not cost much — usually between $10 and $50 depending on your state — but the real cost is in the study time and the written test. Some states also require a skills test or a brief inspection of your vehicle's air brake system.
Key Takeaways
- You must pass a written test on air brake systems, which covers how they work, how to inspect them, and how to respond when they fail.
- Study materials are usually free or low-cost and are available from your state's Department of Motor Vehicles or commercial driver's license manual.
- Some states require a pre-trip inspection or skills demonstration in addition to the written test.
- The endorsement fee is typically $10 to $50 and is paid when you take the test or renew your license.
- You do not need to retake your Class B knowledge or skills test — only the air brake test is required.
Where to get the air brake test in your state
Your state's Department of Motor Vehicles (DMV) or equivalent agency administers the air brake endorsement test. You can find the testing location nearest you by visiting your state's DMV website and searching for "commercial driver's license testing" or "air brake endorsement." Some states allow you to take the test at any DMV office; others have designated testing centers.
Many states also allow third-party testers — private companies licensed by the DMV — to administer the air brake written test. These testers often have more flexible hours and shorter wait times than the DMV itself. You can ask your employer or a local truck driving school whether they know of a third-party tester in your area.
Before you go to the test site, call ahead to confirm they offer air brake endorsement testing, ask what documents you need to bring, and find out whether you need to schedule an appointment or whether it is walk-in.
What to study before the air brake test
The air brake test covers how air brake systems work, how to inspect them before driving, and what to do if they fail. The test is usually 25 to 30 multiple-choice questions, and you typically need to score 80 percent or higher to pass.
Your state's commercial driver's license manual contains all the material you need to know. You can read it free from your state's DMV website, usually as a PDF. The air brake section is typically 10 to 15 pages and covers topics like air pressure, brake chambers, slack adjusters, and emergency procedures.
Some states also offer practice tests online through their DMV website. Taking a practice test once or twice before the real test can help you understand the format and identify weak areas. If you are studying on your own, budget 4 to 8 hours of reading and review time.
Documents and fees you will need
Bring your current Class B commercial driver's license and a valid form of identification — usually a passport or state ID card. Some states also require proof of residency, such as a utility bill or lease agreement dated within the last 60 days. Call the testing site ahead of time to confirm what they require.
The test fee is typically $10 to $50, depending on your state. A few states include it in your license renewal fee; others charge it separately at the time of the test. Some states allow you to pay by cash, check, or card; others accept only certain payment methods. Ask when you call to schedule.
If your state requires a pre-trip inspection or skills demonstration, you will need to bring a vehicle with an air brake system to the testing site. The tester will walk you through a checklist of brake components and may ask you to explain how to perform certain checks or adjustments.
The written test and what happens if you fail
The air brake written test is administered on a computer at most DMV offices and third-party testing sites. You will be seated at a terminal, shown the test rules, and given a set amount of time — usually 30 to 60 minutes — to complete the questions. You can review your answers before submitting, and you will receive your score when ready after you finish.
If you pass, the endorsement is usually added to your license on the spot or within a few days. If you fail, you can retake the test, but you may have to wait a certain number of days — often 7 to 14 days — before your next attempt. There is usually a fee for each retake.
Failing is not uncommon, especially if you have not worked with air brakes before. Most people who study the manual and take a practice test pass on the first or second try. If you fail, review the areas where you struggled and study those sections more carefully before retaking the test.
Air brake restriction versus air brake endorsement
When you first get your Class B license, the DMV may place an air brake restriction on it if you took your skills test in a vehicle without air brakes. This restriction means you can drive Class B vehicles, but only those with hydraulic brakes. You cannot legally drive a Class B vehicle with air brakes unless you remove the restriction by passing the air brake endorsement test.
Some drivers choose to keep the restriction if they know they will only drive hydraulic-brake vehicles. Others remove it right away to keep their options open. There is no penalty for having the restriction — it straightforward limits which vehicles you can operate.
Once you pass the air brake endorsement test, the restriction is removed from your license and replaced with the endorsement notation. This change is permanent unless you let your license expire without renewing it.
Timeline and next steps after passing
After you pass the air brake test, the endorsement is usually added to your license when ready or within 1 to 3 business days. If you took the test at a third-party tester, the results are sent electronically to the DMV, and the endorsement appears in the system within a few days. You can check your license status online through your state's DMV website.
Your physical license card will show the endorsement the next time you renew your license, which is typically every 4 to 8 years depending on your state. In the meantime, you can print a temporary license or receipt from the DMV website that shows the endorsement has been added. Some employers accept this temporary proof; others wait for the updated card.
Once the endorsement is on your record, you can legally operate any Class B commercial vehicle with air brakes. You do not need to renew the endorsement separately — it renews automatically when you renew your Class B license.
Frequently Asked Questions
Can I take the air brake test if I do not own a vehicle with air brakes?
Yes. The written test does not require you to bring a vehicle. However, if your state requires a pre-trip inspection or skills demonstration, you will need access to a vehicle with air brakes. Ask your employer, a truck driving school, or a friend whether you can use their vehicle for the test.
Do I have to retake my Class B skills test to get the air brake endorsement?
No. The air brake endorsement requires only the written test (and possibly a pre-trip inspection in some states). You do not need to retake your Class B knowledge or driving skills test.
What if I fail the air brake test multiple times?
You can retake the test as many times as you need. There is usually a waiting period of 7 to 14 days between attempts and a fee for each retake. If you are struggling, consider taking a truck driving school course on air brakes, which can provide hands-on instruction and practice tests.
Does the air brake endorsement expire?
No. Once you pass the test, the endorsement stays on your license for life, as long as you keep your Class B license active. It renews automatically when you renew your license.
Can I get the air brake endorsement if I have a restriction on my license for other reasons?
Yes. Other restrictions (such as corrective lenses or hearing aids) do not prevent you from getting the air brake endorsement. You only need to pass the air brake test and meet your state's other requirements for that endorsement.