Texas CDL Air Brake Test (TX) 2026

4.9 out of 5 (297 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Howdy, future CDL holders! Get ready to test your knowledge of air brakes with our Texas air brakes practice test . This comprehensive driving practice test features 20 multiple-choice questions that cover all crucial aspects of air brake systems. You'll dive into the nuts and bolts of components like compressors, reservoirs, and brake chambers, while also getting a solid grasp on the operational principles and safety protocols essential for commercial driving. Understanding air brakes is critical for safe driving, and this Texas CDL air brake test goes the extra mile by including questions about the unique "brake lag" time that air brakes have. This lag time is something every driver needs to account for when calculating stopping distances to ensure safety on the road. To pass this Texas drivers license practice test, you'll need to correctly answer at least 16 questions, demonstrating a solid understanding of air brake systems. After you complete the CDL air brakes practice test, you'll receive a detailed summary of your performance. This summary highlights the questions you missed and provides the correct answers, turning each mistake into a learning opportunity. The best part? You can take this Texas DMV practice test anytime, day or night, since it's available online 24/7. No more adjusting your schedule to fit in a test session; you can practice at your convenience. Whether it's early in the morning or late at night, our CDL practice test is always ready for you. All our driving test questions and answers are sourced directly from the official Texas driver's manual. This means you're studying the exact material that will appear on the real DMV permit test. If it's in the manual, it's on our practice test. This ensures you're getting the most accurate and relevant preparation possible. Start preparing for your commercial driver's license air brakes endorsement today. By mastering the fundamentals with our Texas CDL air brakes practice test, you'll be well on your way to safe and effective air brake operation, paving the way for a successful driving career.
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Sample Texas Air Brakes Test Questions

Question 1

The air-compressor governor controls when the compressor pumps air into the storage tanks.

  1. A TRUE
  2. B FALSE

Correct answer: A – TRUE

The governor starts and stops compressor operation according to air-tank pressure. It typically allows pumping to begin near the cut-in pressure of 100 psi and stops pumping near the cut-out pressure of 125 psi. The vehicle manufacturer's specifications determine the applicable operating pressures.

Source: Texas Commercial Motor Vehicle Drivers Handbook — § 5.1.2, “Air Compressor Governor”

Question 2

What directly affects the braking power of spring-operated emergency and parking brakes?

  1. A The brakes becoming hotter
  2. B Proper adjustment of the foundation brakes
  3. C The color of the parking-brake control
  4. D The amount of fuel carried

Correct answer: B – Proper adjustment of the foundation brakes

Spring-brake effectiveness depends on the brakes being properly adjusted. When the foundation brakes are out of adjustment, neither normal service braking nor emergency and parking braking will operate correctly. Drivers should inspect accessible slack adjusters and have adjustment or mechanical problems corrected before operating the vehicle.

Source: Texas Commercial Motor Vehicle Drivers Handbook — § 5.1.14, “Spring Brakes”, Texas Commercial Motor Vehicle Drivers Handbook — § 5.3.2, “Check Slack Adjusters on S-cam Brakes”

Question 3

If the wheels are not chocked, it is acceptable to leave an air-brake vehicle unattended without setting the parking brakes when the stop will be brief.

  1. A TRUE
  2. B FALSE

Correct answer: B – FALSE

Never leave the vehicle unattended without applying the parking brakes or properly chocking the wheels. An unsecured commercial vehicle can roll and cause injury or property damage even during a short absence. If extremely hot brakes or wet brakes in freezing weather make parking-brake use unsafe, secure the vehicle with wheel chocks as directed by the handbook.

Source: Texas Commercial Motor Vehicle Drivers Handbook — § 5.4.8, “Parking Brakes”

Question 4

After securing the vehicle and shutting off the engine, how do you check whether the spring brakes apply automatically?

  1. A Release the parking brakes as required, then repeatedly apply and release the foot brake to reduce air pressure
  2. B Keep the parking brakes applied and hold the foot brake down continuously
  3. C Make a sudden stop at 20 mph or faster
  4. D Repeatedly pull and push the parking-brake control

Correct answer: A – Release the parking brakes as required, then repeatedly apply and release the foot brake to reduce air pressure

During the Texas air-brake inspection sequence, the driver fans the foot brake to lower tank pressure after completing the preceding checks. The parking or emergency-brake valve should pop out between 20 and 45 psi, or at the vehicle manufacturer's specified level. This indicates that the spring brakes have applied automatically as air pressure falls.

Source: Texas Commercial Motor Vehicle Drivers Handbook — § 11.1.2, “Air Brake Check—Emergency Brake(s) Test”

Question 5

During a low-speed service-brake test, pulling to either side may indicate that the brakes are not working correctly.

  1. A TRUE
  2. B FALSE

Correct answer: A – TRUE

The service-brake check is performed by moving forward at about 5 mph, applying the foot brake, and coming to a complete stop. The vehicle should stop effectively without pulling to either side. Pulling or poor stopping performance indicates that the brakes may not be operating correctly and the problem must be addressed before driving.

Source: Texas Commercial Motor Vehicle Drivers Handbook — § 11.1.1, “Service Brake Check”

Question 6

During the applied-brake air-leakage test on a combination vehicle, what is the maximum allowable pressure loss after the gauge stabilizes?

  1. A No more than 2 psi in one minute
  2. B No more than 3 psi in two minutes
  3. C No more than 3 psi in one minute
  4. D No more than 4 psi in one minute

Correct answer: D – No more than 4 psi in one minute

With the engine off, the parking brake and tractor-protection valve released as applicable, fully apply the foot brake. After the initial pressure drop stabilizes, a combination vehicle must not lose more than 4 psi in one minute. The corresponding limit for a single vehicle is no more than 3 psi in one minute.

Source: Texas Commercial Motor Vehicle Drivers Handbook — § 11.1.2, “Air Brake Check—Air Leakage Rate Test”

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