Minnesota CDL Air Brake Test (MN) 2026

4.9 out of 5 (129 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Preparing for your CDL air brakes endorsement in Minnesota is crucial, and the MN CDL air brake test provides a focused, effective way to ensure you are thoroughly prepared. This Minnesota permit practice test is a vital tool for those aiming to pass the CDL air brake section of their licensing test. The test features 20 multiple-choice questions designed to cover all key aspects of air brake systems, including the compressors, reservoirs, and brake chambers. You'll also delve into the operational principles and safety protocols essential for managing these complex systems. Understanding the unique brake lag time in air brakes and how it affects stopping distances is a critical component of the test, equipping you with the knowledge needed to drive safely and effectively. To pass the MN CDL air brake test, you must correctly answer at least 16 out of the 20 questions, setting a high standard for mastery and readiness. Each question on the DPS practice test is derived directly from the official driver's manual-the same source used for the real DMV permit test. This ensures that all the material is accurate and up-to-date, reflecting the latest driving laws and regulations as updated for 2026. Our practice permit test stands out by being tailored specifically to Minnesota's driving conditions, rules, and regulations, providing you with a state-specific study experience that directly prepares you for what to expect on test day. By using the MN DMV air brake test, you're not just practicing; you're enhancing your understanding and ability to handle air brakes effectively under Minnesota's specific driving conditions. This preparation is your stepping stone to achieving your CDL certification, paving the way for a successful career in commercial driving.
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Sample Minnesota Air Brakes Test Questions

Question 1

During an applied air-leakage test on a single vehicle, what is the maximum permitted pressure drop in one minute?

  1. A 3 psi
  2. B 2 psi
  3. C 1 psi
  4. D 4 psi

Correct answer: A – 3 psi

With the system charged to governor cutout, shut off the engine, release the parking brake, fully apply the service brake, and hold it for one minute. A single vehicle must not lose more than 3 psi during that minute. Excessive leakage must be located and repaired before the vehicle is driven.

Source: Minnesota Commercial Driver’s License Manual — § 5.3.3, “Test Air Leakage Rate”.

Question 2

What is the maximum permitted pressure drop during a one-minute applied leakage test on a combination vehicle?

  1. A 2 psi
  2. B 3 psi
  3. C 5 psi
  4. D 4 psi

Correct answer: D – 4 psi

For the applied test, charge the system to governor cutout, turn off the engine, release the parking brakes and tractor-protection valve, and fully apply the service brake. A combination vehicle must not lose more than 4 psi in one minute. A greater loss indicates excessive leakage that must be corrected before driving.

Source: Minnesota Commercial Driver’s License Manual — § 5.3.3, “Test Air Leakage Rate”.

Question 3

During Minnesota cold weather, what daily check is required if the air-brake system has an alcohol evaporator?

  1. A Drain the alcohol container completely
  2. B Add lightweight engine oil to the evaporator
  3. C Replace the alcohol container every day
  4. D Check the alcohol container and fill it as needed

Correct answer: D – Check the alcohol container and fill it as needed

Check the alcohol container every day during cold weather and refill it as necessary. The evaporator introduces alcohol into the air system to reduce the risk of ice forming in valves and other components. Air tanks must still be drained to remove water and oil unless the system has automatic drain valves.

Source: Minnesota Commercial Driver’s License Manual — § 5.1.5, “Alcohol Evaporator”.

Question 4

An alcohol evaporator works by condensing the air inside an air-brake system.

  1. A TRUE
  2. B FALSE

Correct answer: B – FALSE

The statement is false. An alcohol evaporator introduces alcohol into the compressed-air system; it does not condense the air. The alcohol helps reduce the risk of water freezing in brake valves and other components during cold weather, where ice could interfere with brake operation.

Source: Minnesota Commercial Driver’s License Manual — § 5.1.5, “Alcohol Evaporator”.

Question 5

At approximately what pressure does an air-compressor governor normally cut in?

  1. A 80 psi
  2. B 100 psi
  3. C 125 psi
  4. D 150 psi

Correct answer: B – 100 psi

The governor normally allows the compressor to begin pumping again when tank pressure falls to about 100 psi. The Minnesota CDL manual places normal cutout around 120 to 140 psi, but the driver should check the vehicle manufacturer’s specifications. A governor that does not cut in properly may fail to maintain adequate air pressure.

Source: Minnesota Commercial Driver’s License Manual — § 5.1.2, “Air Compressor Governor”.

Question 6

Which foundation-brake design is most common on heavy commercial vehicles?

  1. A S-cam drum brake
  2. B Wedge drum brake
  3. C Hydraulic disc brake
  4. D Band brake

Correct answer: A – S-cam drum brake

Foundation brakes are the brake assemblies located at the wheels. The most common design on heavy commercial vehicles is the S-cam drum brake. When air pressure moves the brake chamber pushrod, the S-cam rotates and forces the brake shoes outward against the inside of the drum.

Source: Minnesota Commercial Driver’s License Manual — § 5.1.8, “Foundation Brakes”.

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