Vermont CDL Air Brake Test (VT) 2026

5 out of 5 (43 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Welcome to our Vermont CDL air brakes practice test. If you're gearing up for your CDL air brake endorsement, this Vermont CDL air brakes practice test is designed to provide you with a thorough and effective study experience. Unlike questionable 'DMV test cheat sheets,' our VT CDL air brakes practice test offers a reliable and legal way to prepare, with a proven history of success. Our learner's permit practice test includes a diverse range of 20 multiple-choice questions that cover every crucial aspect of air brake systems. From understanding the key components like compressors, reservoirs, and brake chambers to mastering the operational principles and safety protocols, this Vermont DMV air brake test ensures you are well-prepared. Special focus is given to the unique brake lag time in air brakes, an essential concept for calculating stopping distances accurately. Achieving a passing score requires correctly answering at least 16 questions. This ensures that you have a comprehensive understanding of the fundamentals necessary for safe and efficient air brake operation. Our Vermont DMV practice test is designed to closely mirror the real DMV test, covering identical topics with similar phrasing. This approach not only helps you familiarize yourself with the test format but also reinforces your knowledge of the essential concepts. In addition to the well-structured questions, our VT practice permit test offers several study aids to enhance your learning experience. If you find yourself stuck on a challenging question, you can request a hint to guide you toward the correct answer. Moreover, if you answer a question incorrectly, a detailed explanation will be provided, helping you understand the reasoning behind the correct answer and reinforcing your learning. By choosing our Vermont DMV air brake test, you are opting for a legitimate and effective study tool. Prepare with confidence, knowing that you are using a trusted resource that is designed to help you succeed. Master the essentials of air brake systems and take a significant step toward earning your CDL air brake endorsement.
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Sample Vermont Air Brakes Test Questions

Question 1

Which sequence describes stab braking during an emergency stop?

  1. A Apply the pedal and hand valve together until the vehicle stops
  2. B Lock the wheels, then release the brakes for the same length of time
  3. C Apply fully until the wheels lock, release until they roll, and apply fully again
  4. D Pump the brake pedal rapidly using light pressure

Correct answer: C – Apply fully until the wheels lock, release until they roll, and apply fully again

With stab braking, apply the brakes fully and release them when the wheels lock. Wait until the wheels begin rolling, then apply the brakes fully again. Reapplying them before the wheels roll can prevent the vehicle from straightening and reduce the driver’s ability to maintain directional control.

Source: Vermont Commercial Driver’s Manual — § 5.4.3, “Emergency Stops—Stab Braking”

Question 2

What is the function of a slack adjuster in an S-cam air brake?

  1. A It regulates pressure inside the air tanks
  2. B It controls when the spring brakes apply
  3. C It changes the amount of brake-pedal free play
  4. D It accounts for slack in the brake linkage

Correct answer: D – It accounts for slack in the brake linkage

The slack adjuster is part of the linkage between the brake chamber pushrod and the S-cam brake camshaft. Pushrod movement turns the slack adjuster, rotating the camshaft and applying the brake shoes. Automatic slack adjusters compensate during full brake applications, but they must still be inspected for excessive movement or mechanical problems.

Source: Vermont Commercial Driver’s Manual — § 5.1.8, “Foundation Brakes—S-cam Brakes”, Vermont Commercial Driver’s Manual — § 5.3.2, “During Step 5 Walk-around Inspection—Check Slack Adjusters on S-cam Brakes”

Question 3

Under normal conditions, when should an air-brake vehicle’s parking brakes be used?

  1. A Only during vehicle inspections
  2. B Whenever the vehicle is parked
  3. C Only when wheel chocks are unavailable
  4. D Whenever the vehicle is slowing

Correct answer: B – Whenever the vehicle is parked

Apply the parking brakes whenever you park under normal conditions. Do not leave the vehicle unattended without applying them or properly chocking the wheels. If the brakes are extremely hot or very wet in freezing temperatures, use wheel chocks on a level surface and allow the brakes to cool or dry before applying the parking brakes.

Source: Vermont Commercial Driver’s Manual — § 5.4.8, “Parking Brakes”

Question 4

With the engine off and brakes released, what air-pressure loss rate is acceptable for a single vehicle?

  1. A Less than 1 psi per minute
  2. B Less than 2 psi per minute
  3. C Less than 3 psi per minute
  4. D Less than 4 psi per minute

Correct answer: B – Less than 2 psi per minute

Begin with a fully charged air system, shut off the engine, and release the parking brake while preventing vehicle movement. Time the pressure drop for one minute. The loss should be less than two psi for a single vehicle; the manual gives a less-than-three-psi rate for a combination vehicle during this released-brake test.

Source: Vermont Commercial Driver’s Manual — § 5.3.3, “Step 7 Final Air Brake Check—Test Air Leakage Rate”

Question 5

During the applied-brake leakage test, how much air may a single vehicle lose?

  1. A No more than 3 psi in one minute
  2. B No more than 2 psi in 45 seconds
  3. C No more than 1 psi in one minute
  4. D No more than 1 psi in 30 seconds

Correct answer: A – No more than 3 psi in one minute

Build the air pressure to governor cutout, shut off the engine, secure the vehicle, release the parking brake, and fully apply the foot brake. Hold the pedal for one minute while watching the gauge. A single vehicle may lose no more than three psi; a greater loss indicates an excessive leak that must be repaired before driving.

Source: Vermont Commercial Driver’s Manual — § 5.3.3, “Step 7 Final Air Brake Check—Test Air Leakage Rate”

Question 6

What is the purpose of an alcohol evaporator in an air-brake system?

  1. A To reduce the chance of ice forming in air valves and other parts
  2. B To increase air-tank pressure above governor cutout
  3. C To eliminate the need to drain manually operated air tanks
  4. D To remove alcohol that has collected in the air tanks

Correct answer: A – To reduce the chance of ice forming in air valves and other parts

The Vermont manual explains that an alcohol evaporator adds alcohol to the air system to reduce ice formation in valves and other components during cold weather. Ice can interfere with brake operation. The alcohol container should be checked during cold weather, and tanks with manual drains must still be drained daily to remove accumulated water and oil.

Source: Vermont Commercial Driver’s Manual — § 5.1.5, “Alcohol Evaporator”

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