Mississippi CDL Air Brake Test (MS) 2026

4.8 out of 5 (51 votes)
80% Passing score
20 Questions
4 Mistakes allowed
As you prepare for your commercial driver's license in Mississippi, mastering the air brake systems is crucial. Our Mississippi CDL air brakes practice test is designed to give you a thorough understanding of the air brake components and their operational principles. This Mississippi DMV practice test consists of 20 multiple-choice questions that delve into essential parts of the system such as compressors, reservoirs, and brake chambers. You'll also tackle questions on the unique brake lag time inherent to air brakes, a vital factor in calculating stopping distances. To pass, you need to correctly answer at least 16 questions, ensuring you're well-prepared for the real test. The Mississippi CDL air brake test is complementary to your formal driver's education. While it doesn't replace a state-certified course, it serves as an excellent supplementary tool to reinforce your learning. By working through these permit test practice questions, you can solidify your understanding of air brake systems, identify any gaps in your knowledge, and ensure you are ready for your Mississippi CDL air brake endorsement. One of the key features of our MS CDL air brakes practice test is its multiple-choice format. This format mirrors the actual written permit test, helping you become familiar with the process of eliminating incorrect answers and honing in on the correct ones. This practice can significantly boost your confidence and improve your test-taking skills. Focusing on your weak areas is essential for success. Our Mississippi air brakes CDL test allows you to pinpoint the areas where you need improvement. By retaking the test as many times as necessary, you can ensure that you fully grasp all the critical aspects of air brake systems. Each attempt will bring you closer to mastering the knowledge required for safe and effective air brake operation. Get started with the Mississippi CDL air brake practice test today, and take a significant step towards acing your commercial driver's license test. With diligent practice and a thorough understanding of the material, you'll be well-equipped to handle any air brake-related challenges on the road.
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Sample Mississippi Air Brakes Test Questions

Question 1

What activates the electrical stop-light switch in an air-brake system?

  1. A A hand control operated by the driver
  2. B Air pressure
  3. C Hydraulic-fluid pressure
  4. D Spring pressure

Correct answer: B – Air pressure

The stop-light switch in an air-brake system is operated by air pressure. When the driver applies the air brakes, the switch completes the electrical circuit and turns on the brake lights. This warns following drivers that the vehicle is braking.

Source: Mississippi Commercial Driver’s License Manual — § 5.1.12, “Stop Light Switch”

Question 2

At 55 mph on dry pavement, air-brake lag adds approximately 32 feet to the stopping distance.

  1. A True
  2. B False

Correct answer: A – True

Air brakes do not respond instantly because compressed air needs time to travel through the system. At 55 mph on dry pavement, the estimated brake-lag distance is about 32 feet. Under good traction and brake conditions, the manual estimates that total stopping distance for an average driver exceeds 450 feet.

Source: Mississippi Commercial Driver’s License Manual — § 5.4.4, “Stopping Distance”

Question 3

On a long, steep downgrade, service brakes should supplement the braking effect of the engine.

  1. A True
  2. B False

Correct answer: A – True

The Mississippi CDL manual teaches that engine braking should be the principal method of controlling speed on a long or steep downgrade. Once the vehicle is in the proper low gear, the service brakes supplement the engine’s braking effect. Excessive brake use creates heat and can cause brake fade or failure.

Source: Mississippi Commercial Driver’s License Manual — § 5.4.6, “Proper Braking Technique”

Question 4

What force normally applies spring parking or emergency brakes when air is released?

  1. A Air pressure
  2. B Spring force
  3. C Hydraulic-fluid pressure
  4. D Electrical force

Correct answer: B – Spring force

Spring brakes use mechanical spring force to apply the brakes. During normal driving, air pressure holds the springs back. Pulling the parking-brake control releases air from the spring-brake chambers, allowing the springs to apply the brakes; a major loss of system air can also cause them to apply.

Source: Mississippi Commercial Driver’s License Manual — § 5.1.14, “Spring Brakes”

Question 5

What indicates that a tractor, truck, or bus is equipped with an antilock braking system?

  1. A A red ABS lamp on the instrument panel
  2. B A yellow ABS malfunction lamp on the instrument panel
  3. C A red lamp on the vehicle’s left exterior
  4. D A red lamp on the vehicle’s right exterior

Correct answer: B – A yellow ABS malfunction lamp on the instrument panel

In the Mississippi CDL manual, tractors, trucks, and buses equipped with ABS have a yellow malfunction lamp on the instrument panel. On newer vehicles, the lamp normally illuminates briefly during startup and then goes out. Trailers use a separate yellow ABS lamp on the left side, near a front or rear corner.

Source: Mississippi Commercial Driver’s License Manual — § 5.1.16, “Antilock Braking Systems (ABS)”

Question 6

Under good conditions, an air-brake vehicle traveling at 55 mph needs only about 100 feet to stop.

  1. A True
  2. B False

Correct answer: B – False

At 55 mph, 100 feet is far too short for the total stopping distance of an air-brake vehicle. The manual’s estimate includes perception distance, reaction distance, approximately 32 feet of air-brake lag, and the distance traveled while the brakes stop the vehicle. Under good conditions, the resulting total is more than 450 feet.

Source: Mississippi Commercial Driver’s License Manual — § 5.4.4, “Stopping Distance”

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