Michigan CDL Air Brakes Practice Test (MI) 2

4.8 out of 5 (67 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Preparing for your Michigan CDL air brakes practice test is an essential step toward getting your commercial driver's license in Michigan. This Michigan CDL air brakes practice test offers a robust selection of 20 multiple-choice questions that delve into crucial topics such as air brake components, operation, safety inspections, and stopping distance calculations. Covering all these areas ensures that you're well-versed in the knowledge needed to safely operate vehicles equipped with air brakes. Michigan's diverse weather conditions can greatly affect driving, making it even more important to understand how air brakes work under different circumstances. From snowy winters to rainy springs, knowing how to handle your vehicle in any weather is crucial. This Michigan CDL air brakes practice test also includes questions about dual air brake systems, a key feature that enhances safety by providing a backup system in case of failure. Our Michigan driving test practice is designed to be comprehensive and up-to-date, reflecting the latest driving laws and regulations for 2026. With a large pool of questions and answers, this DMV practice test provides ample learning opportunities, thoroughly preparing you for the actual DMV written test. Despite being free, this Michigan permit practice test offers the same level of depth and quality as many paid alternatives, ensuring you get the best possible preparation without any cost. Driving in Michigan involves understanding local culture and conditions. Whether it's navigating through Detroit's busy streets or driving across the Mackinac Bridge, this Michigan practice permit test equips you with the necessary knowledge to handle these unique challenges. To pass the air brakes CDL test, you need to answer at least 16 out of 20 questions correctly, a standard that helps ensure you're fully prepared. By using this Michigan CDL air brakes practice test, you can confidently approach your CDL test, knowing that you have covered all the necessary material. The Michigan DMV air brake test is your best resource for thorough and effective preparation, making sure you are ready for any driving situation that comes your way.
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Sample Michigan Air Brakes Test Questions

Question 1

Which instrument is required in an air-brake-equipped commercial vehicle?

  1. A A hydraulic backup gauge
  2. B Two brake-temperature indicators
  3. C An application pressure gauge on every vehicle
  4. D A supply pressure gauge

Correct answer: D – A supply pressure gauge

Federal equipment rules require an air-braked commercial vehicle to have a pressure gauge visible from the normal driving position. The Michigan manual explains that it shows the pressure in the air tanks. A dual system uses separate gauges for each half or one gauge with two needles.

Source: 2024 Michigan Commercial Driver’s License Manual — § 5.1.9, “Supply pressure gauges”, 49 CFR § 393.51(c) – Warning signals, air pressure and vacuum gauges

Question 2

Spring brakes are commonly used to provide which braking functions?

  1. A Hydraulic and power-assist braking
  2. B Normal service braking only
  3. C Parking and emergency braking
  4. D Trailer service braking only

Correct answer: C – Parking and emergency braking

Spring brakes normally provide parking and emergency braking. Air pressure holds powerful springs back while the vehicle is being driven. Releasing or losing that pressure allows the springs to apply the brakes mechanically, rather than depending on air pressure to keep the brakes applied.

Source: 2024 Michigan Commercial Driver’s License Manual — § 5.1.14, “Spring brakes”

Question 3

The safety relief valve is installed in the first tank supplied by the air compressor.

  1. A True
  2. B False

Correct answer: A – True

The safety relief valve is installed in the first tank to which the compressor sends air. It protects that tank and the rest of the system from excessive pressure. The valve is usually set to open at approximately 150 psi, and a release indicates that the system needs mechanical attention.

Source: 2024 Michigan Commercial Driver’s License Manual — § 5.1.6, “Safety valve”

Question 4

On a modern air-brake truck, the low-air warning must operate before reservoir pressure falls below:

  1. A 40 psi
  2. B 50 psi
  3. C 60 psi
  4. D 90 psi

Correct answer: C – 60 psi

The federal vehicle standard requires a continuous warning when service-reservoir pressure is below 60 psi. During the CDL inspection procedure, the warning must activate before the lowest tank drops below that level. Some large buses are designed to warn earlier, commonly at 80 to 85 psi.

Source: 2024 Michigan Commercial Driver’s License Manual — § 5.1.11, “Low air pressure warning”, 49 CFR § 571.121, S5.1.5 – Standard No. 121; Air brake systems

Question 5

On newer air-brake vehicles, what color identifies the diamond-shaped parking-brake control knob?

  1. A Red
  2. B Green
  3. C Yellow
  4. D Pink

Correct answer: C – Yellow

The Michigan CDL manual identifies the newer parking-brake control as a yellow, diamond-shaped push-pull knob. Pulling it out applies the parking or spring brakes, while pushing it in releases them. Older vehicles may use a lever instead of this knob.

Source: 2024 Michigan Commercial Driver’s License Manual — § 5.1.15, “Parking brake controls”

Question 6

What is the primary purpose of a vehicle retarder?

  1. A To prevent every wheel skid
  2. B To apply additional braking to non-drive axles
  3. C To help slow the vehicle and reduce service-brake wear
  4. D To serve as the vehicle’s emergency brake

Correct answer: C – To help slow the vehicle and reduce service-brake wear

Retarders help slow a vehicle, reducing service-brake use and wear. When activated, they generally provide retarding force through the drive wheels when the accelerator is fully released. Because this force can cause drive-wheel skids, the retarder should be turned off on wet, icy, or snow-covered roads.

Source: 2024 Michigan Commercial Driver’s License Manual — § 2.3.4, “Retarders”

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