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CDL Air Brakes Endorsement Practice Test

Pass the CDL Air Brake Test on your very first try! Take our FREE Practice Test for the ultimate test preparation. Our practice tests have 25 multiple choice questions straight from the handbook and give immediate feedback.

Questions number
Mistakes Allowed
Passing Score

Air Brake Connections
Air Brakes ready for Inspection

What do you need to know before you start the Air Brake Endorsement Test?

The Commercial Motor Vehicle Safety Act of 1986 states that operators of trucks and buses with air brakes have to undertake the Air Brake Endorsement (code 15) test. Generally, your initial CDL application includes the fees associated with the are air brake knowledge test. However, if you add the air brake endorsement to your existing CDL, you will have to pay an extra fee that varies by state. Make sure that you check with your licensing office to confirm the actual cost of the endorsement. 


What's on the Air Brake Knowledge Test

There are two parts to the air brake endorsement test; the written and the practical part. The written portion consists of 20 to 25 multiple-choice questions; this test is administered on a computer. Take note! The number of questions might vary depending on the state. For instance, Florida uses a 20-question test, while Alabama uses a 25-question test. The pass mark for the written exam is 80%. Some of the important contents for the written exam includes:

  • Components of an air brake system and dual air brakes.
  • Inspection of the air brake system.The
  • safe use of air brakes. 

For first-time CDL drivers, the knowledge exam is included in the skill test. Those adding an endorsement to their CDL will have to schedule their skill test through their local licensing office. The essence of the practical exam is to ensure that you can safely use air brakes. To pass the practical test (skills test), you will have to demonstrate that you are good at:

  • Using appropriate pressure for different tasks
  • Building air pressure
  • Releasing brakes
  • Testing low air and,
  • Gauging air pressure 

You will not be eligible for the air brake endorsement test with an L and Z restriction on your CDL. L restriction- you cannot drive any vehicle with any air brake system, and with a Z restriction- you can only drive vehicles with a partial air brake system. 

Who needs the Air Brake Written Test?

The air brakes endorsement test applies to all applicants who intend to operate vehicles with air brakes. 

What do you need to have ready to take the Air Brake Knowledge Exam?

  • Your Identification document (You should be at least 21 years of age).
  • Proof of residence
  • a medical examiner's certificate form. 
  • Relevant fees. 

CDL Sample Test Questions

Automatic adjusters should ________.
  • Not have to be manually adjusted.
  • Only be adjusted manually during warm weather.
  • Not have to be adjusted manually except when you are performing maintenance on the brakes and during installation of the slack adjusters.
  • Only be adjusted manually during installation of the slack adjusters.
Automatic slack adjusters ________.
  • Do not need to be checked.
  • Only need to be checked during warm weather.
  • Need to be checked regularly.
  • None of the listed answers.
Brake linings should not be _______.
  • Thin.
  • Loose.
  • Soaked with oil or grease.
  • Loose, thin, or soaked with oil or grease.
How often should alcohol containers be checked during cold weather?
  • Every month.
  • Every week.
  • Every five hours.
  • Every two weeks.
  • Every day.
On newer vehicles with ABS, the malfunction lamp ________.
  • The malfunction lamp comes on when you turn off the car.
  • The malfunction lamp only comes on when something is wrong.
  • The malfunction lamp comes on at start-up for a bulb check and then goes out quickly.
  • The malfunction lamp never comes on.


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