Indiana CDL Air Brakes Practice Test (IN) 2

4.9 out of 5 (75 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Getting ready for your Indiana CDL air brakes endorsement is a crucial step in ensuring you're fully prepared to drive safely and efficiently on the roads of our great state. This Indiana CDL air brakes practice test is designed to help you master the necessary skills and knowledge required to pass the actual DMV air brake test. With 20 multiple-choice questions, you'll cover essential topics like the components of the air brake system, operational procedures, safety inspections, and stopping distance calculations. In Indiana, understanding the specific nuances of local driving conditions can be a game-changer. For instance, knowing how to handle the unique challenges of our seasonal weather-from icy winter roads to rainy spring conditions-can make a significant difference in your driving safety and efficiency. This Indiana CDL air brakes practice test includes questions that mirror those you'll encounter on the actual DMV test, ensuring you're studying the right material straight from the official driver's manual. If the information isn't in the manual, it won't be on the test, giving you confidence that your preparation is spot on. The permit practice test offers immediate feedback on each question, complete with detailed explanations to help you understand why an answer is correct or incorrect. This feature is invaluable in reinforcing your learning and helping you retain critical information. Remember, to pass this Indiana CDL air brake test, you need to answer at least 16 out of 20 questions correctly. Additionally, it's important to note that to obtain your full commercial driver's license, you'll also need to pass the general knowledge test. If you haven't started preparing for that yet, we have a range of general knowledge prep tests available to help you get ready. Indiana's diverse driving environments, from the bustling streets of Indianapolis to the rural backroads of Brown County, demand well-prepared and knowledgeable drivers. This Indiana CDL air brake practice test is an essential tool to ensure you're ready for whatever the road throws your way. So, take advantage of this resource to confidently move one step closer to your CDL endorsement.
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Sample Indiana Air Brakes Test Questions

Question 1

Why do air brakes respond more slowly than hydraulic brakes after the pedal is pressed?

  1. A Air-brake drums rotate at a different speed
  2. B Compressed air must travel through the lines to the brakes
  3. C The return springs must compress first
  4. D The spring brakes must release during every stop

Correct answer: B – Compressed air must travel through the lines to the brakes

The Indiana CDL manual calls this added delay brake lag. After the pedal is pressed, compressed air needs time to travel through the lines and activate the brakes. This commonly takes one-half second or more. Hydraulic brakes do not have this additional air-flow delay.

Source: Commercial Driver’s License Manual – Modernized Testing System — § 5.4.4, “Stopping Distance”

Question 2

What is the primary benefit of an engine retarder?

  1. A It prevents the drive wheels from skidding
  2. B It applies the brakes on non-drive axles
  3. C It helps slow the vehicle while reducing service-brake wear
  4. D It replaces the vehicle’s emergency brakes

Correct answer: C – It helps slow the vehicle while reducing service-brake wear

Retarders supplement the vehicle’s normal braking system by helping reduce speed and service-brake use. Reduced service-brake use can limit wear and heat buildup. When activated, a retarder generally applies its braking effect to the drive wheels as the driver fully releases the accelerator. It does not replace emergency or parking brakes.

Source: Commercial Driver’s License Manual – Modernized Testing System — § 2.3.4, “Retarders”

Question 3

Which instrument is required on an air-braked commercial motor vehicle?

  1. A A gauge showing brake-drum temperature
  2. B A pressure gauge showing the air available for braking
  3. C A separate gauge for each brake chamber
  4. D A gauge showing spring-brake force

Correct answer: B – A pressure gauge showing the air available for braking

An air-braked CMV must have a pressure gauge that the driver can see from the normal driving position. The gauge indicates the air pressure available for braking. A dual system may use separate gauges or one gauge with two needles. Federal safety rules also require an appropriate low-air warning signal.

Source: Commercial Driver’s License Manual – Modernized Testing System — § 5.1.9, “Supply Pressure Gauges”, 49 CFR § 393.51(c) – Warning signals, air pressure and vacuum gauges

Question 4

In an air-brake system, what is a wig-wag device?

  1. A A mechanical arm that drops into view when air pressure is low
  2. B An air-operated switch that activates the brake lights
  3. C An indicator showing excessive slack-adjuster movement
  4. D A lever that controls the trailer relay valve

Correct answer: A – A mechanical arm that drops into view when air pressure is low

The Indiana CDL manual describes a wig-wag as a mechanical low-pressure warning device. Its arm drops into the driver’s view when system pressure falls below 55 psi. An automatic model rises out of view after pressure recovers, while a manual-reset model must be repositioned by the driver. It is not part of the brake-light system.

Source: Commercial Driver’s License Manual – Modernized Testing System — § 5.1.11, “Low Air Pressure Warning”

Question 5

On an older air-brake vehicle with a driver-controlled front-brake limiting valve, which setting should normally be used?

  1. A Normal
  2. B Slippery

Correct answer: A – Normal

The control should remain in the normal position to provide normal stopping power. The slippery setting reduces air pressure to the front brakes by approximately half. Although limiting valves were intended to reduce front-wheel skids, testing showed such skids are unlikely even on ice. Normal front-wheel braking remains important under slippery conditions.

Source: Commercial Driver’s License Manual – Modernized Testing System — § 5.1.13, “Front Brake Limiting Valve”

Question 6

With the engine off and parking brakes released, a single vehicle’s air-loss rate should be less than:

  1. A 1 psi in one minute
  2. B 2 psi in one minute
  3. C 3 psi in one minute
  4. D 4 psi in one minute

Correct answer: B – 2 psi in one minute

Begin with a fully charged air system, turn off the engine, release the parking brake, and monitor the pressure. A single vehicle should lose less than 2 psi in one minute. The released-brake limit for a combination vehicle is less than 3 psi per minute. Excessive leakage must be corrected before driving.

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

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