Tennessee CDL Air Brakes Practice Test (TN) 2

4.9 out of 5 (78 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Get ready for your commercial driver's license with our TN CDL air brake practice test, specifically designed to help you master the air brakes endorsement. This Tennessee DMV practice test offers 20 multiple-choice questions, covering essential topics like air brake components, operation, safety inspections, and stopping distance calculations. One of the critical aspects you'll learn about is the dual air brake system, which ensures safety by providing a backup in case one system fails. To pass this test, you'll need to answer at least 16 questions correctly, making it a thorough preparation tool for your CDL test. Our permit practice test is entirely free, giving you access to high-quality study materials without any cost. We believe that financial barriers shouldn't stand in the way of obtaining your CDL, so our TN DMV permit test practice is packed with features and opportunities that rival any paid test. You'll find that our test is regularly updated to reflect the most current driving laws and regulations, ensuring that you're studying the most relevant information. As of 2026, all our materials have been revised to stay up-to-date with the latest requirements. Living and driving in Tennessee comes with its unique challenges. From the winding roads of the Smoky Mountains to the bustling streets of Nashville, understanding local driving conditions is crucial. Our TN DMV air brake test incorporates state-specific information to help you navigate these roads with confidence. We tailor our questions to the specific rules, regulations, and road signs of Tennessee, providing you with a comprehensive and relevant study experience. Whether you're preparing to drive through the scenic beauty of the Cumberland Plateau or the urban landscape of Memphis, our CDL air brakes practice test ensures you're well-prepared for any situation. This test not only prepares you for the test but also equips you with knowledge that will be invaluable on the road. Take the first step towards earning your CDL by using our TN CDL air brake test - a reliable, up-to-date, and locally relevant study tool designed to help you succeed.
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Sample Tennessee Air Brakes Test Questions

Question 1

When air pressure is removed, what applies the spring brakes?

  1. A Compressed air
  2. B Electrical current
  3. C Hydraulic pressure
  4. D Mechanical force from powerful springs

Correct answer: D – Mechanical force from powerful springs

In a spring-brake system, powerful springs provide the mechanical force that applies the parking and emergency brakes. Air pressure holds the springs back while the vehicle is moving; removing that pressure allows the brakes to apply. The Tennessee manual emphasizes mechanical holding force because compressed air can eventually leak away.

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

Question 2

During cold weather, what daily maintenance does an alcohol evaporator require?

  1. A Drain all alcohol from its container
  2. B Lubricate it with lightweight engine oil
  3. C Replace the alcohol container each day
  4. D Check the alcohol container and refill it as needed

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

Check the alcohol container every day during cold weather and add alcohol when necessary. The evaporator puts alcohol into the air system to reduce ice formation in valves and other components. Air tanks must still be drained daily to remove water and oil unless the system has automatic drain valves.

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

Question 3

A lightly loaded vehicle is less likely to skid when low air pressure causes the spring brakes to apply. True or false?

  1. A True
  2. B False

Correct answer: B – False

Lightly loaded vehicles may skid out of control when their spring brakes apply, especially on slippery roads. The spring brakes can come on after air pressure falls into the low-pressure range. Stop and park safely while enough air remains to use the foot brake in a controlled manner.

Source: Tennessee Commercial Driver’s License Manual — § 5.4.7, “Low Air Pressure”

Question 4

Which description correctly identifies a dual air brake system?

  1. A Two separate air systems operated through one set of brake controls
  2. B Two sets of brake controls connected to one air system
  3. C One air system with separate brake pedals for each axle
  4. D One brake assembly that supplies two air compressors

Correct answer: A – Two separate air systems operated through one set of brake controls

A dual air brake system consists of two separate systems operated by one set of brake controls. Each system has its own tanks, hoses, lines, and pressure indication. The Tennessee manual identifies the two parts as the primary and secondary systems.

Source: Tennessee Commercial Driver’s License Manual — § 5.2, “Dual Air Brake”

Question 5

You should avoid setting the parking brakes while the brakes are extremely hot. True or false?

  1. A True
  2. B False

Correct answer: A – True

Parking brakes should not be applied while the brakes are very hot, such as immediately after descending a steep grade. Heat can damage the parking brakes if they are applied in that condition. On a level surface, use wheel chocks to hold the vehicle and allow the brakes to cool before setting them.

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

Question 6

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

  1. A To reduce ice formation in air brake valves and other parts
  2. B To increase the pressure stored in the air tanks
  3. C To eliminate the need to drain air tanks
  4. D To remove alcohol that collects inside the tanks

Correct answer: A – To reduce ice formation in air brake valves and other parts

An alcohol evaporator introduces alcohol into the air system to reduce the risk of ice forming in valves and other components during cold weather. Ice can interfere with brake operation. The evaporator does not replace daily tank drainage unless the vehicle has automatic drain valves.

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

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