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Based on 2025 ON commercial driver's licence manual
Updated for May 2025
ON Air Brake Test 6
Ready to pass your Ontario Commercial Air Brake endorsement test? Look no further! This comprehensive practice Test 6 is tailored to help you understand the intricacies of air brake system controls and maintenance. With 50 carefully crafted questions, we cover the essential topics and details that you're likely to encounter on your actual test. Don't leave it to chance—get the practice you need and ensure you're prepared on exam day.
Perfect for first-time and renewal commercial applicants, and those adding endorsements
Triple-checked for accuracy
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List of questions (classic view)
Where is the heat produced by friction between brake shoes or pads and brake drums or rotors absorbed and dissipated?
Is there generally a brief delay in air brake response when the brake pedal is pressed or released?
What does the air compressor do with the air it takes in at ambient pressure?
What occurs when you press the brake pedal in a vehicle with disc brakes?
What happens when the brake pedal is pressed for drum brakes?
How much is the cut-out pressure above the cut-in pressure, generally?
Why are air brakes typically used in heavy commercial vehicles?
When you press the brake pedal, pressurized air has to move from one part of the system to another. What helps to make this process as quick as possible?
Which is not a kind of braking system used in commercial vehicles?
Do you need to understand how an air brake system works and how it's different from other vehicle braking systems when operating a vehicle with air brakes?
What is the term for the pressure level when the air compressor starts pumping air?
Which class of vehicles typically use air-over-hydraulic brakes?
An air compressor can be powered directly by the vehicle's engine or by
Another name for the primary and secondary air tanks in a vehicle's air brake system is...
What is the key role of the governor in an air brake system?
What is the benefit of having dual delivery circuits in an air brake system?
What might a decrease in air pressure below the cut-in setting indicate?
In an air brake system, what is the function of the safety valve in the supply tank?
What substance can the mixture of moisture and oil collected from the supply tank form?
The maximum number of separate air pressure gauges a vehicle can have is...
What does the air drawn in by the air compressor contain?
What does the governor do when the air pressure drops to a certain level?
Which air tank should always be drained first when carrying out maintenance on a vehicle's air brake system?
In an air brake system, what device stops the return flow of air to the supply tank?
How frequently should moisture and oil be drained from the tanks in a vehicle's air brake system?
Once the air pumped by the air compressor enters the air dryer, what happens to it?
In certain scenarios, a single cylinder in a vehicle's air brake system may house how many tanks?
Alongside air, what else can mix and settle at the bottom of the tank during the air compressor operation?
What happens if the governor does not signal the compressor to cut out when there is too much pressure build-up?
If the mixture of moisture and oil that collects in the supply tank passes into the rest of the air brake system, it can cause all of the following problems EXCEPT
The actual air brake system pressure range must never exceed...
Where in the air brake system is an air dryer positioned?
Which device can be used in vehicles to decrease the amount of moisture passing into the air brake system?
What is mixed with the air in an air brake system to diminish the freezing propensity of any moisture or ice present?
What could potentially happen if the mixture of moisture and oil accumulating in the supply tank passes into the entire air brake system?
Under what range of air pressure should a vehicle be driven?
What happens with the moisture collected in the air dryer of an air brake system?
Where are the air tanks in a vehicle's air brake system typically located?
What is the name of the initial tank into which compressed air enters in an air brake system?
Another term used to refer to the supply tank in an air brake system is...
When the air exits the supply tank, into how many circuits does it typically split?
Apart from "dual-service tanks", what other term is often used to refer to the primary and secondary air tanks in a vehicle's air brake system?
For each type, size, and style of brake chamber, what specific aspect is distinctive?
In addition to a visible warning, the low air pressure warning device may also activate
What causes the pushrod to return to its original position when the air pressure is released?
What influences the pushrod stroke?
Which term refers to the distance that the pushrod travels out of the chamber when brakes are applied?
If one circuit fails in a dual circuit braking design, what is the outcome?
Are you allowed to drive a vehicle when the air pressure is beyond the routine operating range?
The distribution of air to wheels through the primary or secondary circuits depends on what factor?
Where is the heat produced by friction between brake shoes or pads and brake drums or rotors absorbed and dissipated?
Is there generally a brief delay in air brake response when the brake pedal is pressed or released?
What does the air compressor do with the air it takes in at ambient pressure?
What occurs when you press the brake pedal in a vehicle with disc brakes?
What happens when the brake pedal is pressed for drum brakes?
How much is the cut-out pressure above the cut-in pressure, generally?
Why are air brakes typically used in heavy commercial vehicles?
When you press the brake pedal, pressurized air has to move from one part of the system to another. What helps to make this process as quick as possible?
Which is not a kind of braking system used in commercial vehicles?
Do you need to understand how an air brake system works and how it's different from other vehicle braking systems when operating a vehicle with air brakes?
What is the term for the pressure level when the air compressor starts pumping air?
Which class of vehicles typically use air-over-hydraulic brakes?
An air compressor can be powered directly by the vehicle's engine or by
Another name for the primary and secondary air tanks in a vehicle's air brake system is...
What is the key role of the governor in an air brake system?
What is the benefit of having dual delivery circuits in an air brake system?
What might a decrease in air pressure below the cut-in setting indicate?
In an air brake system, what is the function of the safety valve in the supply tank?
What substance can the mixture of moisture and oil collected from the supply tank form?
The maximum number of separate air pressure gauges a vehicle can have is...
What does the air drawn in by the air compressor contain?
What does the governor do when the air pressure drops to a certain level?
Which air tank should always be drained first when carrying out maintenance on a vehicle's air brake system?
In an air brake system, what device stops the return flow of air to the supply tank?
How frequently should moisture and oil be drained from the tanks in a vehicle's air brake system?
Once the air pumped by the air compressor enters the air dryer, what happens to it?
In certain scenarios, a single cylinder in a vehicle's air brake system may house how many tanks?
Alongside air, what else can mix and settle at the bottom of the tank during the air compressor operation?
What happens if the governor does not signal the compressor to cut out when there is too much pressure build-up?
If the mixture of moisture and oil that collects in the supply tank passes into the rest of the air brake system, it can cause all of the following problems EXCEPT
The actual air brake system pressure range must never exceed...
Where in the air brake system is an air dryer positioned?
Which device can be used in vehicles to decrease the amount of moisture passing into the air brake system?
What is mixed with the air in an air brake system to diminish the freezing propensity of any moisture or ice present?
What could potentially happen if the mixture of moisture and oil accumulating in the supply tank passes into the entire air brake system?
Under what range of air pressure should a vehicle be driven?
What happens with the moisture collected in the air dryer of an air brake system?
Where are the air tanks in a vehicle's air brake system typically located?
What is the name of the initial tank into which compressed air enters in an air brake system?
Another term used to refer to the supply tank in an air brake system is...
When the air exits the supply tank, into how many circuits does it typically split?
Apart from "dual-service tanks", what other term is often used to refer to the primary and secondary air tanks in a vehicle's air brake system?
For each type, size, and style of brake chamber, what specific aspect is distinctive?
In addition to a visible warning, the low air pressure warning device may also activate
What causes the pushrod to return to its original position when the air pressure is released?
What influences the pushrod stroke?
Which term refers to the distance that the pushrod travels out of the chamber when brakes are applied?
If one circuit fails in a dual circuit braking design, what is the outcome?
Are you allowed to drive a vehicle when the air pressure is beyond the routine operating range?
The distribution of air to wheels through the primary or secondary circuits depends on what factor?
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