- Based on 2025 ON commercial driver's licence manual
- Updated for April 2025
ON Air Brake Test 9
Get ready for Ontario Commercial Air Brake Test 9. This exam will take you through the ins and outs of emergency braking techniques. With 50 questions, we've meticulously curated this test to ensure it covers all the material you'll face in the real deal. Start practicing now to get ahead.
- Perfect for first-time and renewal commercial applicants, and those adding endorsements
- Triple-checked for accuracy
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What you need to know
Verified by Steven Litvintchouk, M.S., Chief Educational Researcher, Member of ACES. See our detailed commitment to accuracy and quality in our practice tests.
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What to expect on the official exam
50
questions
40
correct answers to pass
80
passing score
Our commitment to accuracy and quality in our practice tests
Explore our rigorous, multi-tiered verification process that ensures each question mirrors the official manual for unparalleled accuracy.
Written by Andrei Zakhareuski Updated over a week ago
At Tests.ca, we understand the importance of reliable and accurate practice tests to help you prepare for your driver's knowledge exam. That's why we've developed a meticulous process to create and continually update our practice questions, ensuring they reflect the most current driving laws and regulations.
Here's an inside look at how we maintain the highest quality in our practice tests.
Content Creation and Verification Process
- Alignment with Official Driving Handbooks:
Every question we develop is based on the most recent version of each province's official driving manual. Our team regularly monitors each province's official website for the latest updates to ensure our practice tests are always aligned with the most current information. - Community Feedback Integration:
We leverage feedback from our vast community of users to understand which topics are most frequently tested. This helps us focus on the areas that are most relevant and beneficial for your preparation. - Expert Content Creation:
Our in-house editor, Steven, who has extensive experience in driver education, crafts each question with precision. He conducts a thorough review of each question against the official manuals to ensure accuracy. - Rigorous Review Process:
Once Steven has finalized a set of questions, our team conducts a joint review session. This second level of scrutiny involves content accuracy, proofreading, and fact-checking to eliminate any errors. - User Feedback Mechanism:
After a question goes live on our site, we keep the lines of communication open. Each question features a feedback button, inviting users to report any issues or errors. This continuous feedback loop allows us to address and rectify any concerns promptly. - Responsive Updates:
In line with our commitment to accuracy, we quickly update our practice questions to reflect any changes in the provincial government manuals. Additionally, we update the free electronic copy of the state's driver's license manuals on our site, typically within a few days after the government publishes them.
Our thorough quality control process ensures that you have access to practice tests that are as accurate and up-to-date as possible. We believe in the power of well-prepared drivers and are dedicated to providing you with the best study tools to help you succeed on your driver's knowledge exam.
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List of questions (classic view)
- Where should ABS indicators typically be mounted on trailers?
- Who can be charged for driving a vehicle with defects or for failing to conduct the required inspections?
- Which statement is incorrect? Drivers are expected to identify brake components that are...
- To ensure balanced braking, how should slack adjusters on each side of an axle be?
- Which brake hoses and tubes are the most prone to damage?
- If all other air brake chambers function but one has a defect, is it lawful to drive the vehicle on any road or highway?
- When must air compressors always be inspected?
- Slack adjusters usually have how many holes designed for pushrod attachment?
- Which statement is incorrect? Damage or deterioration to brake hoses and tubes may be in the form of...
- What typically influences the setting of the governor pressure?
- At what point do the air pressure gauges cease to rise?
- The low air pressure warning device should be tested at _______ or higher.
- What is the maximum acceptable rate of air loss for a tractor and trailer combination?
- What should occur after the regular draining of air tanks?
- How long should you observe air pressure readings to test the air loss rate of a brake system?
- To test air pressure build up time, what should be the speed of the engine?
- A vehicle passes the system air-loss rate test when the drop in pressure is...
- The vehicle passes the test when the device activates at or above what psi on both primary and secondary air tank gauges?
- Whenever what event occurs, a trailer's spring brakes must automatically engage?
- Which of the following is not one of the procedures for testing air-compressor governor settings?
- Even with regular drainage, a prominent amount of moisture being discharged from the supply tank is...
- Which of the following does not apply when testing a tractor (towing vehicle) protection valve?
- The low air pressure warning device fails if it does not activate or if it turns on when pressure is below
- What is the maximum acceptable air loss rate for a straight truck, tractor, or bus?
- Any oil found in any air tank except the supply tank should be
- Which of the following is not a procedure for testing low air-pressure warning devices?
- When the engine is idling between 600 and 900 rpm, how long should it take for the air pressure to rise from 85 to 100 psi?
- In testing the low air-pressure warning device, pressure in the system must be reduced to the point where the device activates or at what psi, whichever is higher?
- The vehicle fails the test if the low air pressure warning device does not activate or activates when pressure is below what psi on both primary and secondary air tank gauges?
- For the test of air-pressure build-up time, the system air pressure should be reduced to below
- The vehicle fails the system air-loss rate test when...
- What poses a concern if oil is discovered in any air tank, apart from the supply one?
- The range of the system pressure is controlled by what?
- The air brake system should be considered defective if the cut-out pressure is
- What's the maximum acceptable air loss rate for a tractor towing two or more trailers?
- When the tractor protection valve is tested, the tractor passes the test when...
- What isn't a step when testing spring (parking and emergency) brakes?
- What's the effect of compressor cut-in during air compressor governor settings test?
- What isn't a required step when testing the automatic activation of trailer spring brakes?
- Which of the following is not correct? You should inspect brake chambers at each wheel for...
- Is it possible to fit brake-stroke indicators to brake linkage?
- If a driver is found to be operating a vehicle with defects, what will happen to the vehicle?
- You are testing the tractor protection valve with a trailer that lacks an anti-compounding valve. What should you do?
- Certain body designs and suspensions of some vehicles may hinder safe access to air tanks and drains. What should be done in such cases?
- When checking the automatic application of trailer spring brakes, if you're unsure whether they have been applied, what should you do?
- Which of the following is not a requirement for a brake inspection of a truck in a practical examination? You must know your vehicle's brake chamber size and type and bring which of these?
- Which of the following is not a mandatory step when testing the air-tank drain valves?
- A brake chamber pushrod is normally labeled with what?
- What is the most common size for a brake chamber?
- When testing the tractor protection valve, from where should you note if air is escaping?
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