CDL Exam’s Air Brakes Endorsement

The open road on a big rig. There’s nothing quite like it. Whether it’s long or short-haul driving, there are more than 3.5 million professional truckers in the United States. Handling these big rigs entails more than getting behind the wheel. Drivers must understand their truck’s parts and how they perform. That’s why truckers who drive vehicles with air brakes take the CDL Exam’s Air Brakes Endorsement test. The exam tests a driver’s knowledge of air brake systems and encompasses several important areas that directly tie to a vehicle’s braking performance. It’s a huge safety issue. What’s on the test? How can you study for this test? Our guide answers those questions.

What is CDL Exam’s Air Brakes Endorsement test?

It’s an exam that tests a driver’s ability to inspect air brakes. Understanding system leaks, warning signals, and emergency breaking are all important. It’s also an important test because anyone who fails may not be eligible to take the road test.

Is there one CDL exam?

Not necessarily. The exam components can differ from state to state. That’s why it’s important to understand the local rules.

Where can I take the exam?

You should consult with your local driver’s license or motor vehicle bureau to see where you can take the exam in your area.

Do I have to take the CDL Exam’s Air Brakes Endorsement exam?

All truckers who drive vehicles with air brakes must take and pass the exam. Truckers who do not pass the test will not be allowed to drive vehicles with air brakes.

What about fees? How do I find out about those?

Again, check with your local bureau. While states generally assess a fee for background checks, there could be additional fees that vary.    

What are the common themes I can expect to see on the test?

The exam is likely to test your knowledge in several areas involving breaking systems, including parts, dual systems, air brake inspection, and air brake usage. You can expect to see content areas that include:

  • Air brake system parts
  • The air compressor, compressor governor, storage tanks, and tank drains
  • Alcohol evaporator and the brake pedal
  • Foundation brakes that include drums, shoes, linings, wedge and disc brakes
  • Pressure issues, including supply pressure and application pressure gauges, and low pressure warnings
  • Parking brake controls, like dual parking and modulating control valves
  • Anti-local breaking issues

Drivers could also be asked to:

  • Show they understand dual air system minimum psi pressure issues to ensure the air brake system is operating properly
  • Conduct air brake inspections
  • Check the condition and tightness of the air compressor drive belt
  • Perform a walk around inspection
  • Perform a low-pressure warning signal test
  • Make sure the spring brakes automatically come on
  • Check the rate of air pressure buildup
  • Test the air leak rate
  • Check the air compressor governor cut-in and cut-out pressures
  • Check the parking and service brakes
  • Show a knowledge of braking systems during normal and emergency stops
  • Show a knowledge of proper antilock brakes application and braking techniques
  • Demonstrate an understanding of the brake lag distance and the total stopping distance
  • Demonstrate a knowledge of air brake system components and location

Other questions could include:

  • The importance of being in the proper gear before going downhill
  • The factors that can lead to fading or failure of breaks
  • Factors for parking brake usage
  • Techniques for air tank draining
  • Slack adjusters, including understanding what they are and how to check them
  • Checks to ensure spring brakes automatically deploy
  • Understanding supply pressure gauge and spring brakes

What are the best study materials I can buy to help me pass the CDL Air Brakes test?

Mometrix has the study materials you need. Our study guide can help you prepare for the CDL exam. Our study guide offers tips to solving the questions you’re most likely to see on the test. The study guide explains concepts in an easy-to-understand way that sticks with the candidates. Our flashcards are another handy tool. Truckers are on the road a lot, and this portable tool means you can study where ever your rig takes you. The large-format cards are easy to read and the answers to the questions easy to understand. Both are excellent materials.

by Enoch Morrison | Last Updated: January 11, 2019