Maryland CDL Air Brake Test (MD) 2026

5 out of 5 (94 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Preparing for your Maryland CDL air brakes endorsement has never been easier with our DMV practice test. This Maryland CDL air brakes practice test features 20 multiple-choice questions that cover the entire scope of air brake systems. From essential components like compressors, reservoirs, and brake chambers to operational principles and vital safety protocols, this Maryland CDL air brakes practice test ensures you're well-versed in every aspect of air brake operation. One unique feature of the Maryland CDL air brakes practice test is its inclusion of questions about brake lag time. This often-overlooked aspect of air brakes is crucial for calculating stopping distances, and mastering this will give you a significant advantage on your actual test. The Maryland CDL air brakes practice test is designed to be stress-free, providing an ideal learning environment without the pressure of the real test. With no time constraints, you can focus on understanding the material thoroughly. Our questions are meticulously written and reviewed by professional driving instructors who have decades of teaching experience and have assisted thousands of drivers in obtaining their licenses. Additionally, this Maryland CDL air brakes practice test is packed with study aids to enhance your learning experience. If you find yourself stuck on a difficult question, you can request a hint to steer you in the right direction. If you answer a question incorrectly, a detailed explanation of the correct answer will be provided, helping you to learn from your mistakes and improve. To pass this Maryland CDL air brakes practice test, you need to correctly answer at least 16 questions. Achieving this score will demonstrate your readiness for the Maryland CDL air brakes endorsement and solidify your understanding of the fundamental concepts necessary for safe and effective air brake operation. By taking this Maryland MVA air brake test, you are setting yourself up for success and ensuring that you have the knowledge and confidence to operate air brakes safely and efficiently.
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Sample Maryland Air Brakes Test Questions

Question 1

The air-compressor governor's cut-in pressure is usually around:

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

Correct answer: B – 100 psi

When tank pressure falls to the cut-in level, the governor allows the compressor to begin pumping again. The CDL manual gives a typical cut-in level of about 100 psi. Federal vehicle standards specify a minimum cut-in pressure of 100 psi for trucks and 85 psi for buses.

Source: Maryland Commercial Driver License Manual — § 5.1.2, “Air Compressor Governor”, 49 CFR 571.121, S5.1.1.1 — Standard No. 121; Air Brake Systems

Question 2

The air-compressor governor's cut-out pressure is usually around:

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

Correct answer: C – 125 psi

As air-tank pressure rises to the cut-out level, the governor stops the compressor from pumping. The typical cut-out level given in the CDL manual is about 125 psi. Cut-in occurs later, after tank pressure drops to approximately 100 psi.

Source: Maryland Commercial Driver License Manual — § 5.1.2, “Air Compressor Governor”

Question 3

The S-cam drum brake is the most common type of foundation brake.

  1. A TRUE
  2. B FALSE

Correct answer: A – TRUE

Foundation brakes are installed at the vehicle’s wheels, and the S-cam drum brake is the most common type. Air pressure moves a pushrod and slack adjuster, rotating the S-cam. The S-shaped cam forces the brake shoes against the inside of the drum to slow the vehicle.

Source: Maryland Commercial Driver License Manual — § 5.1.8, “Foundation Brakes”

Question 4

If you will be away from an air-brake vehicle only briefly, you may leave it unattended without applying the parking brake or chocking the wheels.

  1. A TRUE
  2. B FALSE

Correct answer: B – FALSE

A brief absence does not make it safe to leave the vehicle unsecured. Apply the parking brakes or use wheel chocks to prevent the vehicle from rolling. If the brakes are extremely hot or wet in freezing conditions, the manual directs the driver to use chocks while allowing the brakes to cool or dry.

Source: Maryland Commercial Driver License Manual — § 5.4.8, “Parking Brakes”

Question 5

Which method should be used to control an air-brake vehicle on a long, steep downgrade?

  1. A Apply the service brakes continuously throughout the downgrade
  2. B Use only the trailer brakes to hold a safe speed
  3. C Use stab braking each time the vehicle gains speed
  4. D Use engine braking, then brake at the safe speed until about 5 mph below it

Correct answer: D – Use engine braking, then brake at the safe speed until about 5 mph below it

Select the proper low gear before beginning the downgrade and use the engine’s braking effect as the main speed control. When the vehicle reaches its safe speed, apply the brakes firmly enough to produce a definite slowdown. Release them at about five mph below the safe speed, then repeat as necessary.

Source: Maryland Commercial Driver License Manual — § 5.4.6, “Proper Braking Technique Downhill”

Question 6

As air-tank pressure drops, the visible low-air warning should activate before pressure falls below:

  1. A 40 psi
  2. B 50 psi
  3. C 55 psi
  4. D 90 psi

Correct answer: C – 55 psi

Maryland’s current CDL manual states that the visible warning must activate before tank pressure falls below 55 psi. Older vehicles may use one-half of the governor cut-out pressure, while large buses commonly warn at 80–85 psi. Federal vehicle standards require a continuous warning whenever service-reservoir pressure is below 60 psi, so the warning may activate earlier.

Source: Maryland Commercial Driver License Manual — § 5.1.11, “Low Air Pressure Warning”, 49 CFR 571.121, S5.1.5 — Standard No. 121; Air Brake Systems

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