- Updated for March 2025
- Based on 2025 TX commercial driver's license manual
Free Texas CDL Air Brakes Test 2025
Passing the Texas DMV CDL Air Brakes Knowledge Test is essential for anyone looking to operate commercial motor vehicles (CMVs). Without passing, your CDL will include the restriction “L,” preventing you from operating CMVs with air brakes. Failing the air brakes test results in a one-day waiting period and a fee before you can retake it. Our Texas DMV CDL Air Brakes Practice Tests are designed to help you pass your knowledge exam on the first attempt.
Air brakes are essential for navigating Texas’s flat plains and rolling hills as well as the steep inclines and winding highways of its deserts and mountains. The winter snow and ice in the northwestern regions make air brakes important for heavy rigs to safely navigate.
Texas is a major transportation hub for the U.S. and Mexico, with such critical highways as I-10 (crossing east-west through flat and mountainous terrain), I-20 (connecting to Georgia and the southeastern U.S.), I-35 (connecting to Mexico and Oklahoma), and I-45 (linking Houston and Dallas). As most semi-trucks and tractor-trailers are equipped with air brakes, restriction “L” would limit your marketability.
The air brake qualification is crucial for employment across the Lone Star State’s leading industries, including oil, technology, agriculture, and logistics. Major companies using air brakes include ExxonMobil, Chevron, and Texas Instruments in the manufacturing sector and Halliburton and Baker Hughes in the energy industry. Pilgrim’s Pride and JBS in the agriculture sector require air brake-qualified drivers as do Greyhound Lines and Texas Trails in the tourism and charter bus services. Even the thousands of Texas full-size school buses use air brakes and have this requirement. The “L” restriction makes operating CMVs equipped with air brakes illegal and these jobs unattainable.
Our CDL Air Brakes Practice Tests cover essential knowledge for the official DMV Air Brakes knowledge test. This test features multiple-choice questions based on the state’s CDL manual (Texas CDL Handbook 2025) and requires a minimum passing score of 80%. The information you learn will also help you pass your skills test, which includes inspecting components, testing for air pressure and leaks, and operating air brake-equipped vehicles.
Our Practice Tests are engineered to offer real-time feedback on all responses and mimic material you will face on the official knowledge test. This approach improves retention and ensures you’re prepared to pass the official test.
- 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 TX DMV exam
questions
correct answers to pass
passing score
List of questions (classic view)
- What is the best way to test if your vehicle's spring brakes come on automatically?
- How do brakes work on a long, steep downgrade?
- At what measurement is the safety valve USUALLY set to open?
- The purpose of a supply pressure gauge is
- Slack adjusters are
- Which of the following should you do before leaving your vehicle unattended?
- Under which conditions are front wheel brakes good?
- How can you tell if your vehicle is equipped with an antilock braking system (ABS)?
- After the initial drop, the maximum acceptable leakage rates per minute are
- Which of the following is NOT part of the air brake system?
- How would you check your truck's slack adjusters?
- Which of the following can cause brakes to fade or fail?
- An antilock braking system (ABS)
- Spring brakes are
- Which of the following is NOT part of the drum brake?
- When should you drain your air tanks?
- When should you use the parking brake?
- The tractor protection valve
- Why must you pass a knowledge test on air brakes?
- Which of the following is NOT part of the braking process when you're driving a tractor-trailer combination vehicle with an antilock braking system (ABS)?
- Which of the following are true about a dual air brake system?
- Which vehicles must have low air pressure warning signals?
- What is the best way to test your vehicle's low air pressure warning signal?
- If the air tanks are not drained,
- Which of the following will be true about your brake function if your antilock braking system (ABS) fails?
- 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
- You are on a steep downgrade and have reached your safe speed of 40 mph. You would apply the service brakes until your speed drops to
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