- 0 Incorrect (6 allowed to pass)
- 0 Correct
- Updated for February 2025
- Based on 2025 IA commercial driver's license manual
Free Iowa CDL Air Brakes Test 2025
Passing the Iowa DOT CDL Air Brakes Test is crucial for driving large commercial motor vehicles (CMVs). Our practice materials are the perfect tool to prepare you for the DOT tests. Without passing, your CDL will include the restriction “L” prohibiting you from operating CMVs with air brakes. Semi-trucks, tractor-trailers, and full-size buses are typically equipped with air brakes. As such, the air brakes qualification is a requirement of most companies due to the commonality of this braking system. Iowa’s flat terrain can often be accompanied by strong winds (especially in open agricultural areas), which require precise braking and control to manage these gusts. Heavy rains and flooding often make roads slick and hazardous, necessitating air brakes.
Industries across the Hawkeye State rely on drivers with the air brake qualification. These include agriculture, manufacturing, renewable energy, transportation and logistics, and insurance and finance (particularly in Des Moines). Key companies requiring the air brakes qualification include Molex (Lincoln) and Heartland Express (North Liberty), both large outfits in the trucking industry. Charter bus companies like Iowa Motorcoach (Des Moines) and Luxury Bus Charters (Des Moines) and bus drivers across the state’s many school districts provide transportation for large groups, thus needing air-brake-qualified drivers. Iowa is a major agricultural state, relying on drivers for the transport of farm equipment, grains, and livestock. The state is home to Landus Cooperative (Ames) and Farmers Cooperative (Marion), both requiring air brake qualifications. Simply put, the “L” restriction makes operating CMVs equipped with air brakes illegal, and the above job prospects won’t be open to you.
The official two-part DOT 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 the state’s CDL manual.
Our CDL Air Brakes Practice Tests cover all topics likely to be addressed on the official DOT knowledge test. Their format is similar to that of the official test. If you miss a question, you will be notified immediately so you can learn quickly and pass 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 IA DOT exam
questions
correct answers to pass
passing score
List of questions (classic view)
- How would you check your truck's slack adjusters?
- Which of the following will be true about your brake function if your anti-lock braking system (ABS) fails?
- Under which conditions are front wheel brakes good?
- Which vehicles must have low air pressure warning signals?
- Which of the following is NOT part of the drum brake?
- Which of the following can cause brakes to fail or fade?
- Which of the following should you do before leaving your vehicle unattended?
- When should you use the parking brake?
- The purpose of a supply pressure gauge is
- If the air tanks are not drained,
- Which of the following are true about a dual air brake system?
- Which of the following is NOT part of the air brake system?
- Slack adjusters are
- 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)?
- What is the best way to test if your vehicle's spring brakes come on automatically?
- The tractor protection valve
- How do brakes work on a long, steep downgrade?
- At what measurement is the safety valve USUALLY set to open?
- An anti-lock braking system (ABS)
- Spring brakes are
- Why must you study air brakes in the state of Iowa?
- What is the best way to test your vehicle's low air pressure warning signal?
- When should you drain your air tanks?
- How can you tell if your vehicle is equipped with an anti-lock braking system (ABS)?
- After the initial drop, the maximum acceptable leakage rates per minute are
- 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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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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