North Dakota CDL Air Brake Test (ND) 2026

4.9 out of 5 (49 votes)
80% Passing score
20 Questions
4 Mistakes allowed
If you're preparing for your North Dakota CDL air brake endorsement, our ND DMV air brake test is your best resource. This comprehensive North Dakota practice permit test includes 20 multiple-choice questions designed to cover all critical aspects of air brake systems. From understanding compressors, reservoirs, and brake chambers to mastering operational principles and safety protocols, this ND drivers permit practice test ensures you're well-prepared for your endorsement test. One unique feature of air brakes is the brake lag time, which is crucial for calculating stopping distances accurately. Our permit test practice covers these specific nuances to help you understand and anticipate real-world driving conditions. Achieving a passing score requires correctly answering at least 16 questions, making sure you have a solid grasp of the essentials needed for safe and efficient air brake operation. The North Dakota air brakes CDL test is accessible online through various platforms, including mobile, desktop, and mobile apps. This flexibility means you can study anytime, anywhere, making it easier to fit preparation into your busy schedule. And the best part? Our ND DMV air brake test is completely free. Unlike many other paid practice tests, our CDL air brake practice test offers just as many features and study opportunities without any cost to you. It's important to note that obtaining your commercial driver's license requires passing the general knowledge test as well. If you need additional preparation, we offer a variety of general knowledge prep tests to ensure you're fully equipped for all aspects of the CDL test. Our free and comprehensive North Dakota CDL air brake test provides you with the focused preparation you need to pass your air brakes endorsement test with confidence.
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Sample North Dakota Air Brakes Test Questions

Question 1

Which air-brake component may introduce alcohol into the system to reduce cold-weather icing?

  1. A. An air-compressor heater
  2. B. An air-reservoir warmer
  3. C. An alcohol evaporator
  4. D. A one-way check valve

Correct answer: C. – An alcohol evaporator

Some air-brake systems use an alcohol evaporator to introduce alcohol into the compressed air. This reduces the risk of ice forming in valves and other components during North Dakota's cold-weather conditions. If the vehicle has this equipment, check and fill its alcohol container as necessary; daily air-tank drainage is still needed unless automatic drains are installed.

Source: North Dakota Commercial Driver License Manual 2025–2027 — § 5.1.5, “Alcohol Evaporator”

Question 2

In a dual air system with standard-size reservoirs, pressure should rise from 85 to 100 psi within 45 seconds when the engine is at operating rpm.

  1. A. True
  2. B. False

Correct answer: A. – True

The CDL air-brake check uses a benchmark of 85 to 100 psi within 45 seconds for a dual system when the engine is running at operating rpm. A vehicle with reservoirs larger than the minimum size may safely take longer. Always compare the result with the vehicle manufacturer's specifications before driving.

Source: North Dakota Commercial Driver License Manual 2025–2027 — § 5.3.3, “Step 7 Final Airbrake Check”

Question 3

The stopping power of spring parking and emergency brakes depends primarily on:

  1. A. The air-compressor cut-out pressure
  2. B. The size of the air reservoirs
  3. C. Whether the tanks have automatic drain valves
  4. D. The adjustment of the foundation brakes

Correct answer: D. – The adjustment of the foundation brakes

Spring brakes apply mechanical force when air pressure is released, but their braking power still depends on correctly adjusted brake assemblies. If the brakes are out of adjustment, the regular service brakes and the emergency or parking brakes will not work properly. Brake adjustment is therefore important to every part of the air-brake system's performance.

Source: North Dakota Commercial Driver License Manual 2025–2027 — § 5.1.14, “Spring Brakes”

Question 4

What is the main reason air-brake reservoirs must be drained?

  1. A. To complete the lighting inspection
  2. B. To activate the air-leak warning device
  3. C. To remove accumulated water and compressor oil
  4. D. To test the governor's cut-out pressure

Correct answer: C. – To remove accumulated water and compressor oil

Compressed air normally contains some moisture and compressor oil, which collect at the bottoms of the reservoirs. North Dakota's CDL manual instructs drivers to drain manually operated tanks completely at the end of each driving day. Removing these contaminants helps prevent corrosion and cold-weather freezing that could interfere with brake operation.

Source: North Dakota Commercial Driver License Manual 2025–2027 — § 5.1.4, “Air Tank Drains”

Question 5

Which condition can reduce the effectiveness of both the service brakes and the spring parking or emergency brakes?

  1. A. Low hydraulic fluid in an unrelated system
  2. B. Brake assemblies that are out of adjustment
  3. C. An empty alcohol-evaporator container in warm weather
  4. D. Normal air pressure at governor cut-out

Correct answer: B. – Brake assemblies that are out of adjustment

Poor brake adjustment affects more than normal service braking. Spring parking and emergency brakes act through the foundation brake assemblies, so they also lose effectiveness when those brakes are not properly adjusted. Correct adjustment is necessary for the vehicle's regular, parking, and emergency braking functions to work as intended.

Source: North Dakota Commercial Driver License Manual 2025–2027 — § 5.1.14, “Spring Brakes”

Question 6

Why must the correct low gear be selected before starting down a long, steep grade?

  1. A. Engine braking should control most of the speed, with service brakes used as a supplement
  2. B. The selected gear guarantees that the brakes cannot overheat
  3. C. The transmission will eliminate the need to monitor speed
  4. D. A low gear allows the brake pedal to be held down continuously

Correct answer: A. – Engine braking should control most of the speed, with service brakes used as a supplement

Engine braking should be the principal method of controlling speed on a long or steep downgrade. Selecting the proper low gear before the descent provides that braking effect before speed builds. Service brakes should supplement engine braking; excessive use can create enough heat to cause brake fade or failure.

Source: North Dakota Commercial Driver License Manual 2025–2027 — §§ 2.16.2, “Select the Right Gear Before Starting Down the Grade”; 2.16.4, “Proper Braking Technique”

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