- Updated for January 2025
- Based on 2025 IL commercial driver's license manual
Free Illinois CDL Air Brakes Test 2025
Planning to drive commercial motor vehicles (CMVs) equipped with air brakes? Our practice materials are the perfect tool to prepare you for the DMV tests. Without passing, your CDL will include the restriction “L,” indicating you’re prohibited from operating CMVs with air brakes. Since semi-trucks and tractor-trailers are typically equipped with air brakes, obtaining this endorsement is essential. In fact, in Illinois, the air brakes qualification is a requirement of most companies due to the commonality of this braking system. From the flat plains of southern Illinois to the urban interchanges around Chicago and the icy winter conditions on major highways, air brake qualification is key to safety and control.
Industries across the Prairie State rely on drivers with the air brake qualification. Logistics and freight companies, charter bus services, school transportation, agriculture, manufacturing, and warehousing are just a few that require this. Schneider National, J.B. Hunt, and FedEx Freight all use vehicles equipped with air brakes. Intercity bus services like Greyhound and Megabus rely on drivers with the qualification. Additionally, regional groups like Windy City Limousine (in Chicago) and school districts are on the list because their vehicles are outfitted with air brakes. In the agriculture sector, air brakes are needed for the transport of corn, soybeans, and livestock. Likewise, the manufacturing and warehousing industries need the qualification for jobs with Caterpillar and Amazon. Simply put, the “L” restriction makes operating CMVs equipped with air brakes illegal, thus limiting your job prospects.
The official two-part DMV test covers the parts of an air brake system, effective operation, and air-brake inspection procedures. The skills test requires you to physically inspect an air brake system, identify its components, and operate a vehicle equipped with air brakes. This test includes checking air pressure, testing the brakes for leaks, and more. The multiple-choice written test requires a score of at least 80% to pass and features questions directly from material found in the state’s CDL manual (https://m.driving-tests.org/illinois/il-cdl-handbook/).
Our Illinois CDL Air Brakes Practice Tests take into consideration all that is required for the official DMV knowledge test and mimic the content and format you will face on the test. Our practice test questions and answers provide responses in real time so you can learn quickly and be confident of passing your official exam.
- Perfect for first-time and renewal CDL/CLP applicants, and those adding endorsements
- Triple-checked for accuracy
What you need to know
What to expect on the actual IL DMV exam
questions
correct answers to pass
passing score
Helpful links
List of questions (classic view)
- Which of the following are true about a dual air brake system?
- At what measurement is the safety valve USUALLY set to open?
- Slack adjusters are
- The tractor protection valve
- Which of the following is NOT part of the air brake system?
- How do brakes work on a long, steep downgrade?
- Which of the following can cause brakes to fail or fade?
- Why must you study air brakes in the state of Illinois?
- Which of the following is NOT part of the braking process when driving a tractor-trailer combination vehicle with an anti-lock braking system (ABS)?
- When should you use the parking brake?
- What is the best way to test your vehicle's low air pressure warning signal?
- What is the best way to test if your vehicle's spring brakes come on automatically?
- Which of the following should you do before leaving your vehicle unattended?
- The purpose of a supply pressure gauge is
- How would you check your truck's slack adjusters?
- After the initial drop, the maximum acceptable leakage rates per minute are
- Which of the following will be true about your brake function if your anti-lock braking system (ABS) fails?
- If the air tanks are not drained,
- How can you tell if your vehicle is equipped with an anti-lock braking system (ABS)?
- Which of the following is NOT part of the drum brake?
- When should you drain your air tanks?
- Spring brakes are
- An anti-lock braking system (ABS)
- Which vehicles must have low air pressure warning signals?
- Under which conditions are front wheel brakes good?
- The low air pressure warning signal will come on before the pressure in the air tanks falls below
- A low pressure warning signal is required on
- All vehicles equipped with air brakes have
- With air brake-equipped vehicles, the parking brakes should be used
- The use of air brakes on a downgrade is only a supplement to the
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Here's an inside look at how we maintain the highest quality in our practice tests.
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We leverage feedback from our vast community of users to understand which topics are most frequently tested. This helps us focus on the areas that are most relevant and beneficial for your preparation. - Expert Content Creation:
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Our thorough quality control process ensures that you have access to practice tests that are as accurate and up-to-date as possible. We believe in the power of well-prepared drivers and are dedicated to providing you with the best study tools to help you succeed on your DMV exam.
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