Colorado CDL Air Brakes Practice Test (CO) 2

5 out of 5 (72 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Welcome to the ultimate Colorado CDL air brakes practice test, tailored to help you ace your commercial driver's license air brakes endorsement test. Our comprehensive Colorado CDL air brake practice test is designed to simulate the real test, with 20 multiple-choice questions covering crucial topics such as components, operation, safety inspections, and stopping distance calculations. Colorado's unique terrain, with its mountainous regions and varied weather conditions, demands that drivers have a thorough understanding of air brake systems to ensure safety on the road. This Colorado permit test practice is not just about answering questions; it's an interactive learning experience. Each question provides immediate feedback and detailed explanations, helping you understand why an answer is correct or incorrect. This immediate feedback mechanism enhances your learning process, ensuring you grasp the essential concepts required for the CDL test. Our focus on dual air brake systems, for example, highlights their importance in enhancing safety by providing a backup in case one system fails-a crucial feature when navigating Colorado's steep inclines and winding roads. Written and reviewed by professional driving instructors with decades of experience, our questions reflect real-world scenarios you might encounter while driving through Colorado. The expert input ensures that the content is both accurate and practical, giving you the confidence that you are learning from the best. You can take this practice permit test as many times as needed, allowing you to get comfortable with the questions and format before moving on to the next set of CDL practice tests. Preparing for your CDL air brake test with our Colorado permit practice test means you're getting ready to handle the challenges of driving in diverse Colorado conditions, from high-altitude passes to urban streets. With a passing score requirement of 16 out of 20, our practice test ensures you cover all necessary topics in one comprehensive session. By the time you complete this DMV practice test, you'll be well-equipped to face the real CDL air brake test and confident in your ability to drive safely and efficiently across Colorado.
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Sample Colorado Air Brakes Test Questions

Question 1

The three basic air-brake functions are service braking, parking braking, and emergency braking.

  1. A TRUE
  2. B FALSE

Correct answer: A – TRUE

Colorado's CDL manual describes air brakes as three braking systems: service, parking, and emergency. The service system operates during normal brake-pedal use, while the parking system holds the parked vehicle. The emergency system uses parts of the service and parking systems when a brake-system failure occurs.

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

Question 2

Which instrument is found on every air-brake-equipped vehicle?

  1. A A backup hydraulic-pressure gauge
  2. B Two electric brake heaters
  3. C An application-pressure gauge
  4. D A supply-pressure gauge

Correct answer: D – A supply-pressure gauge

Every air-brake vehicle has a supply-pressure gauge connected to an air tank. It displays the air pressure available in the tanks. A dual system uses separate gauges for its two parts or one gauge with two needles, while an application-pressure gauge is optional and shows the pressure being applied to the brakes.

Source: Commercial Driver License Manual — § 5.1.9, “Supply Pressure Gauges”

Question 3

During cold weather, what daily check is required if the air-brake system has an alcohol evaporator?

  1. A Drain all alcohol from the container
  2. B Lubricate the evaporator with engine oil
  3. C Replace the alcohol container each morning
  4. D Check the alcohol level and refill as needed

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

Colorado's CDL manual instructs drivers to check the alcohol container every day during cold weather and refill it as needed. The evaporator introduces alcohol into the air system to reduce the risk of ice formation. Air tanks must still be drained daily unless the system has automatic drain valves.

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

Question 4

During an applied air-leakage test, what is the maximum acceptable pressure loss for a combination vehicle?

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

Correct answer: D – 4 psi in one minute

For an applied-leakage test, build pressure to governor cutout, shut off the engine, release the parking brakes and tractor protection valve, and fully apply the foot brake. After the gauges stabilize, hold the pedal for one minute. A combination vehicle that loses more than 4 psi has excessive leakage and must be repaired before driving.

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

Question 5

For a typical air-brake vehicle, the visible low-pressure warning must activate before tank pressure falls below:

  1. A 80 psi
  2. B 55 psi
  3. C 45 psi
  4. D 20 psi

Correct answer: B – 55 psi

Colorado's CDL manual states that the visible low-air-pressure warning must activate before tank pressure falls below 55 psi. On an older vehicle, the threshold may be one-half of the compressor governor cutout pressure. Large buses commonly have warning devices that activate at a higher pressure, often between 80 and 85 psi.

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

Question 6

A supply-pressure gauge measures how long it will take an S-cam to rotate.

  1. A TRUE
  2. B FALSE

Correct answer: B – FALSE

A supply-pressure gauge displays the amount of air pressure in the vehicle's air tanks. In a dual air-brake system, each part has its own gauge or is represented by a separate needle on one gauge. The instrument does not measure S-cam movement or the time needed for the brakes to apply.

Source: Commercial Driver License Manual — § 5.1.9, “Supply Pressure Gauges”

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