Oregon CDL Air Brakes Practice Test (OR) 2

5 out of 5 (54 votes)
80% Passing score
20 Questions
4 Mistakes allowed
If you're preparing for your CDL air brakes endorsement in Oregon, you're in the right place. Our Oregon CDL air brake practice test is designed to give you the confidence and knowledge needed to pass the real test. With 20 multiple-choice questions that mirror the format and content of the official test, you'll become familiar with the types of questions you can expect. To pass the Oregon CDL air brakes practice test, you'll need to answer at least 16 questions correctly, ensuring a thorough understanding of essential topics such as air brake components, operation, safety inspections, and stopping distance calculations. This Oregon DMV air brake test is tailored to cover the specific endorsement requirements, focusing solely on questions that appear on the CDL permit test for air brakes. While this is an essential step in your commercial driver's license journey, remember that you must also pass the general knowledge test to obtain your CDL. We offer a range of general knowledge prep tests to support you in that endeavor. Available online 24/7, the Oregon DMV practice test is convenient and flexible, allowing you to study at a time that suits your schedule. Whether you're nestled in the lush greenery of the Willamette Valley or navigating the bustling streets of Portland, this test is accessible anytime, anywhere. Understanding the unique driving conditions in Oregon, from rainy days in the Pacific Northwest to mountain driving in the Cascades, is crucial. This practice test not only helps you master the mechanics of air brakes but also prepares you for the diverse driving challenges you might face across the state. With an emphasis on realism and relevance, the Oregon practice permit test ensures you're well-prepared to tackle the real test. Dive into this comprehensive preparation tool and take the next step towards earning your CDL with confidence. Ready when you are, this permit practice test is your gateway to mastering the air brakes endorsement.
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Sample Oregon Air Brakes Test Questions

Question 1

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

  1. A. A mechanical arm that warns of low air pressure
  2. B. A valve that limits pressure to the front brakes
  3. C. An air-operated switch for the brake lights
  4. D. A gauge that displays brake application pressure

Correct answer: A. – A mechanical arm that warns of low air pressure

Oregon’s CDL manual describes a wig-wag as a low-air warning device that lowers a mechanical arm into the driver’s view when system pressure drops below 55 psi. An automatic model rises when pressure exceeds 55 psi. A manual-reset model must be repositioned by hand and will not remain out of view until sufficient pressure is restored.

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

Question 2

If an S-cam slack adjuster moves more than about one inch where the push rod attaches, it probably needs adjustment. True or false?

  1. A. True
  2. B. False

Correct answer: A. – True

To check an accessible slack adjuster, park on level ground, chock the wheels, release the parking brakes, and pull firmly while wearing gloves. Movement exceeding about one inch at the push-rod connection indicates that adjustment is probably needed. An out-of-adjustment automatic slack adjuster may indicate a mechanical problem that should be professionally corrected.

Source: Oregon Commercial Driver Manual — § 5.3.2, “During Step 5 Walk-around Inspection”

Question 3

Under normal conditions, when should you apply the parking brakes on an air-brake-equipped vehicle?

  1. A. Only during vehicle inspections
  2. B. Whenever you park the vehicle
  3. C. Only when parked on a grade
  4. D. Whenever you need to slow in traffic

Correct answer: B. – Whenever you park the vehicle

Oregon’s CDL manual directs drivers to use the parking brakes whenever they park. Exceptions apply when the brakes are extremely hot or are very wet in freezing temperatures; wheel chocks should then be used on a level surface. Never leave a vehicle unattended without applying the parking brakes or chocking the wheels.

Source: Oregon Commercial Driver Manual — § 5.4.8, “Parking Brakes”

Question 4

Which driving practice can overheat the brakes and cause brake fade or failure?

  1. A. Driving through heavy rain
  2. B. Overusing the service brakes
  3. C. Operating in congested traffic
  4. D. Checking the parking brake

Correct answer: B. – Overusing the service brakes

Braking produces heat, and repeated or prolonged use of the service brakes can create more heat than the system can manage. Excessive heat changes the brake lining and expands the drums, reducing braking force. On downgrades, proper gearing and the engine’s braking effect help limit service-brake use.

Source: Oregon Commercial Driver Manual — § 5.4.5, “Brake Fading or Failure”

Question 5

What information does an air supply pressure gauge provide?

  1. A. The pressure currently being applied to the brakes
  2. B. The air pressure stored in the tanks
  3. C. The amount of air used during the trip
  4. D. The temperature of the air compressor

Correct answer: B. – The air pressure stored in the tanks

The supply pressure gauge indicates how much pressure is in the air tanks. A dual air-brake system has a gauge for each half of the system or one gauge with two needles. An application pressure gauge, when provided, shows the pressure being applied to the brakes instead.

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

Question 6

What is the primary purpose of an engine retarder?

  1. A. To prevent every type of skid
  2. B. To apply the brakes on non-drive axles
  3. C. To help slow the vehicle and reduce brake wear
  4. D. To replace the emergency braking system

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

Oregon’s CDL manual explains that retarders provide another way to slow a vehicle, reducing service-brake use and wear. When activated, they generally apply retarding force to the drive wheels after the accelerator is released. Because poor traction can allow those wheels to skid, the retarder should be turned off on wet, icy, or snow-covered roads.

Source: Oregon Commercial Driver Manual — § 2.3.4, “Retarders”

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