Oklahoma CDL Air Brakes Practice Test (OK) 2

4.9 out of 5 (58 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Navigating the roads in Oklahoma requires more than just a standard driver's license; it requires a deep understanding of the specific conditions and challenges drivers might face. That's why we've crafted this Oklahoma CDL air brake test specifically for those seeking their commercial driver's license endorsement. With this comprehensive written driving test practice, you'll dive into 20 multiple-choice questions designed to prepare you thoroughly for the Oklahoma permit test practice. Unlike many paid alternatives, our Oklahoma CDL air brake test is entirely free, yet it boasts all the features you'd expect from a high-quality practice permit test. You'll explore a wide range of topics essential for any aspiring CDL holder, including the components of air brake systems, operational nuances, safety inspections, and the crucial calculations for stopping distances. Understanding how dual air brake systems function as a safety net in case of system failure is just one of the many critical insights you'll gain. Each question in our Oklahoma DMV air brake test has been carefully crafted and reviewed by professional driving instructors with decades of experience. These experts have guided thousands of drivers toward obtaining their licenses, ensuring that the questions you encounter are both accurate and relevant. Our Oklahoma DMV practice test provides immediate feedback on each question, complete with detailed explanations to clarify why an answer is correct or incorrect. This feedback is crucial for deepening your understanding and boosting your confidence as you prepare for the real test. Driving in Oklahoma is unique, with its mix of urban environments and wide-open spaces, each posing distinct challenges. Whether you're cruising down Route 66 or navigating the bustling streets of Oklahoma City, having a robust understanding of your vehicle's air brake system is crucial for safety. Our air brakes CDL test equips you with the knowledge you need to handle these diverse driving conditions confidently. Prepare to tackle your Oklahoma permit test practice with confidence. Our free, expertly designed test ensures you're well-equipped to join the ranks of CDL drivers who navigate the beautiful and challenging roads of Oklahoma with skill and safety.
FREE CDL Practice Test App
Pass your Oklahoma CDL Air Brake test with the NextDoorDriving app. Real questions and answers—100% free and ad-free.
Download on the App Store

Sample Oklahoma Air Brakes Test Questions

Question 1

Which practice can overheat air brakes and lead to brake fade?

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

Correct answer: B – Overusing the service brakes

Repeated or continuous use of the service brakes generates excessive heat and can reduce friction at the brake linings. Continued overheating may leave the vehicle unable to slow or stop effectively. The Oklahoma manual advises using proper gearing and engine braking rather than depending too heavily on the service brakes, especially on downgrades.

Source: Oklahoma Commercial Driver’s License Manual — § 5.4.5, “Brake Fading or Failure”

Question 2

What medium transmits braking force through an air-brake system?

  1. A Water
  2. B Compressed air
  3. C Compressor oil
  4. D A mixture of water and oil

Correct answer: B – Compressed air

Compressed air is stored in tanks and used to operate the brakes. The Oklahoma manual notes that compressed air may contain water and compressor oil, but these substances are harmful contaminants. They collect in the tanks and must be removed through the drain valves to help prevent improper operation or freezing.

Source: Oklahoma Commercial Driver’s License Manual — §§ 5.1.3–5.1.4, “Air Storage Tanks” and “Air Tank Drains”

Question 3

What does an air-brake “wig wag” do?

  1. A Drops a mechanical warning arm into the driver’s view when air pressure is low
  2. B Automatically adjusts excessive brake-chamber travel
  3. C Activates the vehicle’s stop lamps
  4. D Drains moisture from the air tanks

Correct answer: A – Drops a mechanical warning arm into the driver’s view when air pressure is low

A wig wag warns the driver of low air pressure by dropping a mechanical arm into view. The manual describes it as operating when system pressure falls below 55 psi. An automatic model rises when pressure recovers, while a manual-reset model must be returned to its normal position by hand.

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

Question 4

What should you do when the low-air-pressure warning activates while driving?

  1. A Stop and safely park as soon as possible
  2. B Shift into a higher gear
  3. C Pump the brake pedal repeatedly
  4. D Open the trailer air-supply control

Correct answer: A – Stop and safely park as soon as possible

The Oklahoma manual directs the driver to stop promptly and park safely when the low-air warning activates. Low pressure can prevent part of a dual air-brake system from operating fully and increase stopping distance. Do not continue until the air-brake problem has been repaired.

Source: Oklahoma Commercial Driver’s License Manual — § 5.2, “Dual Air Brake”

Question 5

How should you prepare to check reachable slack adjusters by hand?

  1. A Apply the service brakes and leave the wheels unchocked
  2. B Drain every air tank and start the engine
  3. C Park on level ground, chock the wheels, and release the parking brakes
  4. D Apply the parking brakes and place the transmission in gear

Correct answer: C – Park on level ground, chock the wheels, and release the parking brakes

Park on level ground, chock the wheels, and release the parking brakes before pulling firmly on each reachable slack adjuster. Releasing the parking brakes allows the adjusters to move during the inspection. Movement of more than about one inch where the pushrod connects indicates that adjustment or repair is probably needed.

Source: Oklahoma Commercial Driver’s License Manual — § 5.3.2, “During Step 5 Walk-around Inspection”

Question 6

For a truck or bus covered by FMVSS No. 121, the low-air warning must operate when service-reservoir pressure is below:

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

Correct answer: C – 60 psi

Federal equipment standards require a continuous warning when service-reservoir pressure falls below 60 psi on trucks and buses covered by FMVSS No. 121. The warning must be visible within the driver’s forward field of view or be both audible and visible. Separate requirements apply to older power units that were not covered by that standard.

Source: 49 CFR § 393.51(c) — Warning signals, air pressure and vacuum gauges, 49 CFR § 571.121 S5.1.5 — Standard No. 121; Air brake systems

More Oklahoma CDL Practice Tests
Other CDL Endorsements