Indiana CDL Air Brake Test (IN) 2026

4.8 out of 5 (130 votes)
80% Passing score
20 Questions
4 Mistakes allowed
As a proud Hoosier, getting ready for your commercial driver's license in Indiana involves mastering the essentials of air brake systems, a critical component for safe driving. Our Indiana CDL air brakes practice test is here to assist you in this important task. This Indiana CDL air brake test features 20 multiple-choice questions, each designed to cover various aspects of air brake systems. You'll delve into the workings of key components such as compressors, reservoirs, and brake chambers. Understanding the operational principles and safety protocols is crucial, and our practice test ensures you are well-prepared. One unique feature of air brakes is the brake lag time, which significantly affects stopping distances. Our Indiana air brakes CDL test includes questions to help you understand and calculate this critical factor. To pass, you'll need to correctly answer at least 16 questions, giving you a well-rounded preparation for your air brakes endorsement. Unlike some DMV test cheat sheets that promise quick fixes and shortcuts, our Indiana practice drivers test is a reliable and trustworthy study tool. You can take your time, as the permit practice test is not timed, allowing you to work through each question thoroughly. Immediate feedback and detailed explanations are provided for each question, ensuring you understand why an answer is correct or incorrect, aiding in your learning process. This method helps build a solid foundation, crucial for safe and effective air brake operation. Choosing our Indiana CDL air brake practice test means opting for a lawful and effective way to prepare for your DMV air brake test. Our resources are designed to offer you the best chance of success, ensuring you're well-equipped with the knowledge needed for your commercial driving career. With a proven history of effectiveness, this Indiana practice permit test is your go-to resource for mastering air brakes. Prepare confidently with our Indiana CDL air brake test, knowing you have a trusted and comprehensive tool at your disposal. By focusing on understanding rather than shortcuts, you'll ensure a successful and safe driving experience in your commercial driving career.
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Sample Indiana Air Brakes Test Questions

Question 1

After securing the vehicle and turning off the engine, how do you test whether the spring brakes apply automatically?

  1. A Release the parking brake and repeatedly apply and release the foot brake
  2. B Set the parking brake and repeatedly press the foot brake
  3. C Make a hard stop while traveling at least 20 mph
  4. D Repeatedly apply and release only the parking-brake control

Correct answer: A – Release the parking brake and repeatedly apply and release the foot brake

The Indiana CDL procedure begins with the vehicle safely secured and the air system charged. With the engine off and parking brake released, repeatedly apply and release the foot brake to reduce tank pressure. The appropriate brake-control valve should pop out at the manufacturer’s specification, generally between 20 and 45 psi, applying the spring brakes.

Source: Indiana Commercial Driver’s License Manual — § 5.3.3, “Step 7 Final Air Brake Check”

Question 2

What additional factor makes an air-brake vehicle’s total stopping distance longer than that of a hydraulic-brake vehicle?

  1. A Perception distance
  2. B Reaction distance
  3. C Brake-lag distance
  4. D Sight distance

Correct answer: C – Brake-lag distance

Air brakes do not begin working immediately when the driver presses the pedal. The time required for air to travel through the lines and activate the brakes is called brake lag. Total stopping distance includes perception distance, reaction distance, brake-lag distance, and braking distance.

Source: Indiana Commercial Driver’s License Manual — § 5.4.4, “Stopping Distance”

Question 3

Which air-brake system is intended to help stop the vehicle if the service brake system fails?

  1. A Hand-brake system
  2. B Drum-brake system
  3. C Emergency brake system
  4. D Parking-brake control only

Correct answer: C – Emergency brake system

An air-brake vehicle has service, parking, and emergency brake systems. The emergency brake system uses parts of the service and parking systems to stop the vehicle during a brake-system failure. Spring brakes commonly provide the mechanical force needed for emergency and parking braking.

Source: Indiana Commercial Driver’s License Manual — § 5, “Air Brakes”

Question 4

For the standard CDL air-brake check, the low-air warning should activate before pressure falls below approximately what level?

  1. A 80 psi
  2. B 55 psi
  3. C 40 psi
  4. D 20 psi

Correct answer: B – 55 psi

The Indiana CDL manual uses 55 psi as the standard low-air warning threshold, unless the vehicle manufacturer specifies another level for the inspection procedure. The warning must activate before pressure falls below that point. Some large buses normally provide the warning at a higher pressure, often around 80–85 psi.

Source: Indiana Commercial Driver’s License Manual — § 5.1.11, “Low Air Pressure Warning”

Question 5

If an air-brake vehicle does not have automatic tank drains, when should its air tanks be drained?

  1. A At the end of each week
  2. B At the beginning of each week
  3. C At the beginning of each working day
  4. D At the end of each working day

Correct answer: D – At the end of each working day

Indiana CDL guidance calls for manually drained air tanks to be emptied at the end of each working day. Draining removes accumulated water and compressor oil. Water can freeze in cold weather and interfere with the air-brake system, potentially causing brake failure.

Source: Indiana Commercial Driver’s License Manual — § 5.1.4, “Air Tank Drains”

Question 6

During an applied-brake leakage test, a combination vehicle is limited to only 1 psi of air-pressure loss per minute.

  1. A True
  2. B False

Correct answer: B – False

With the service brake fully applied, a combination vehicle may lose no more than 4 psi in one minute. The corresponding maximum for a single vehicle is 3 psi per minute. A loss exceeding the applicable limit indicates excessive leakage that must be corrected before the vehicle is driven.

Source: Indiana Commercial Driver’s License Manual — § 5.3.3, “Step 7 Final Air Brake Check”

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