Are you a Commercial Driver’s License (CDL) driver wanting to drive a compressed – air- brake system? Then taking the CDL Air brakes Test is a must. In this CDL Air Brakes Study Guide, we are going to provide you all the information you need about this test and how to ace it. Check it out now!

cdl air brakes test
CDL Air Brakes Test Study guide

1. Why do you need to take the CDL Air Brakes test?

 Drivers of Commercial Motor Vehicles (CMVs) are required to have a Commercial Driver’s License (CDL). In order to get a CDL, you must take The CDL Test, which consists of a General knowledge test, Endorsement tests, and an Air Brakes test. An Air Brakes test is one of the requirements for anyone wishing to drive a vehicle with air brakes (heavy trucks or buses). If you fail the Air Brakes test, there will be a mark of restriction (restriction L) in your CDL, which means that you are not able to drive a CMV with air brakes. You can look at the table below to know more about the basic restrictions in all American states:


Restriction Description
E Drivers can’t operate a commercial vehicle with a manual transmission
L Drivers can’t drive a vehicle equipped with a full air brakes system
M Drivers can only operate:

  • School busses
  • Class B passenger vehicles
  • Class C passenger vehicles
N Drivers can only operate:

  • School bus
  • Class C passenger
O Drivers can’t drive a Class A vehicle with a fifth-wheel connection
V Drivers have medical variances:

  • Diabetic
  • Hearing
  • Seizure
  • Vision impairments
Z Drivers can’t operate a vehicle with a full air brake system


>> See more: CDL General Knowlege Test Study guide

2. What is the format of the CDL Air brakes test?

air brakes test
CDL Air brakes test format

2.1. How many questions on the CDL Air Brakes test?

CDL Air brakes test includes 2 main parts: written and practical part. 

The written CDL air brakes test depending on which state are you in is about 20 – 25 multiple choices questions. Besides, the written test will be done on computers, you should pay attention to this issue. To qualify for the written test, your score should be at least 80%.

If this is your first time as a CDL driver, you must take the practical test (skill test). This test will be done when you show up at the local licensing office and show the staff here your skill in using air brakes safely.

2.2. What are the contents of the CDL Air Brakes test?

The written test contains some important content, make sure you all remember and clearly understand about CDL air brakes test system:

  • Components and Features of air brakes system: The examination will check your knowledge of how air brakes system work and your ability to use them.
  • Inspection of the air brakes system: You must understand the advantage and disadvantages of the air brakes system and know how to fix it
  • Main differences between traditional and air brakes: There is a big difference between them, it is the properties of air, make sure you know what they are.
  • Safety in using the air brakes system: Ensure you know how to control the system and use it effectively.

In the Practical test (skills test), you will have to demonstrate skills that you are good at:

  •  Using appropriate pressure for different task
  • Building air pressure
  • Releasing brakes
  • Testing low air 
  • Gauging air pressure 

3. How to pass the CDL Air Brakes test?

3.1. Practice carefully

Not only on the CDL Air Brakes test but also on every test that you take, the best way to get a high score is to practice as much as you can. Make sure that you’re well-prepared and have a clear opinion about what you are going to deal with in the test. There are various ways to practice, in this article, we suggest you some:

  • Read the DMV manual: the manual provides you the general information on the CDL Brakes test, a study guide, and some tips. This is the most trustworthy source to read before taking the test.
  • Prepare some flashcards: If online programs can not help, do the traditional way. You can write questions on flashcards, pick them up randomly and answer them.
  • Take practice tests: You can practice by taking the online CDL Practice test. Check on our website now, we have everything you need to practice for not only CDL Brake Test but also the whole CDL system. 
air brakes cdl
Make sure you remember all of the air brake system

3.2. Attend offline or online courses

Nowadays, there are many virtual and non-virtual classes for CDL tests. You can register for a course on CDL, they will guide you on how to succeed in CDL tests, including the Air Brakes test. However, we recommend you take some online courses, to save your time. You can look for free courses or websites to prepare before taking the CDL air brakes test. 

3.3. Keep calm and relax

Emotional feeling plays an important role in the result of the test. Don’t be too nervous, keep calm and show the examiner your good attitude (especially in practical tests). Besides, make sure that you feel your best by eating well and staying hydrated before your test. 

3.4. Be on time

Do not forget to include the time you need to find the test center, the parking place, and the room to take the test. If possible, you should be earlier 5 – 10 minutes to prepare and revise all the knowledge of the test.


In conclusion, we hope that the CDL Air brakes test study guide will help you have a closer look at the CDL Air brakes test. Do not forget to practice all flashcards and mock tests on our website to master the CDL Air brakes test and get a flying score in the actual test. Good luck with your exam!