Ontario AZ Licence Practice Test 2026: Practice test 4

Practice test 4 of 6 for the Ontario AZ Licence Practice Test: 25 more questions with answers and explanations.

Commercial vehicle
Ontario
150 questions
Checked October 10, 2026

Question 1 of 25
What applies the spring brakes?
- The driver's foot on the pedal
- A large spring, which air pressure holds back
- Air pressure pushing on the diaphragm
- Hydraulic fluid
Show answer
Answer: B. A large spring, which air pressure holds back
Spring brakes are applied by a strong spring and released by air pressure, so they apply when air is lost.
Question 2 of 25
The low air pressure warning must come on before pressure drops below what level?
- 690 kPa (100 psi)
- 380 kPa (55 psi)
- 138 kPa (20 psi)
- 552 kPa (80 psi)
Show answer
Answer: B. 380 kPa (55 psi)
The warning is defective if it does not activate or if it activates below 380 kPa (55 psi). Most activate at 414 kPa (60 psi) or higher.
Question 3 of 25
What is the adjustment limit for a type 30 long-stroke chamber?
- 64 mm (2-1/2 inches)
- 89 mm (3-1/2 inches)
- 45 mm (1-3/4 inches)
- 51 mm (2 inches)
Show answer
Answer: A. 64 mm (2-1/2 inches)
A type 30 long-stroke chamber (with square ports and stroke markings) has a 64 mm (2-1/2 inch) limit.
Question 4 of 25
How often should you check the push rod stroke (brake adjustment)?
- At least daily
- Only after a crash
- Once a month
- Once a year
Show answer
Answer: A. At least daily
The handbook says brake adjustment should be checked at least daily.
Question 5 of 25
What helps reduce brake heat on long downgrades?
- Shifting to neutral
- Pumping the brake pedal quickly
- Using an engine brake or retarder
- Turning off the air compressor
Show answer
Answer: C. Using an engine brake or retarder
Engine brakes and retarders slow the vehicle without heating the service brakes.
Question 6 of 25
How do you know the tractor protection valve is defective during the test?
- The low air warning comes on at 414 kPa (60 psi)
- Air exhausts from the trailer service line when you press the pedal
- The trailer spring brakes apply when you close the supply valve
- The governor cuts out at 828 kPa (120 psi)
Show answer
Answer: B. Air exhausts from the trailer service line when you press the pedal
With the trailer supply closed, pressing the pedal should not send air out of the trailer service line.
Question 7 of 25
When draining the air tanks at the end of the pre-trip check, which tank do you drain first?
- The primary tank
- The secondary tank
- The supply (wet) tank
- The trailer tank
Show answer
Answer: C. The supply (wet) tank
Drain the supply tank first, because it collects most of the water and oil, then check each drain valve.
Question 8 of 25
In the air brake practical exam, which brake adjustment method must you demonstrate?
- Adjusting the slack adjusters yourself
- The applied push rod stroke measurement method
- Kicking the tires
- Listening to the brakes while driving
Show answer
Answer: B. The applied push rod stroke measurement method
Candidates must show the applied method of measuring push rod stroke.
Question 9 of 25
Which item must you bring to the air brake practical test?
- Wheel chocks and a watch or stopwatch with a second hand
- A tire iron and a jack for the steering axle
- A spare brake chamber and a set of wrenches
- A second licensed driver to hold the steering wheel
Show answer
Answer: A. Wheel chocks and a watch or stopwatch with a second hand
Bring wheel chocks, a timing device, a way to hold the brake pedal down and tools to mark and measure push rod stroke.
Question 10 of 25
What does the air dryer do?
- Dries the tires after driving through rain
- Removes moisture before air enters the supply tank
- Measures the air pressure in each tank
- Heats the brake drums so they work in winter
Show answer
Answer: B. Removes moisture before air enters the supply tank
The air dryer removes moisture before the air reaches the supply tank.
Question 11 of 25
If you double both your weight and your speed, how much longer is the stopping distance?
- Two times longer
- Four times longer
- Eight times longer
- Sixteen times longer
Show answer
Answer: C. Eight times longer
Doubling both weight and speed makes the stopping distance eight times longer.
Question 12 of 25
What is the first step to get a Z endorsement in Ontario?
- Take an air brake endorsement course from an approved provider
- Pass a medical exam at a hospital or clinic
- Drive a vehicle with air brakes for six months
- Book a road test in a tractor-trailer at DriveTest
Show answer
Answer: A. Take an air brake endorsement course from an approved provider
You first take an air brake course from a fleet owner, community college or safety organization.
Question 13 of 25
What is the adjustment limit for a standard type 30 clamp-type brake chamber?
- 76 mm (3 inches)
- 32 mm (1-1/4 inches)
- 51 mm (2 inches)
- 64 mm (2-1/2 inches)
Show answer
Answer: C. 51 mm (2 inches)
A standard type 30 chamber has an adjustment limit of 51 mm (2 inches).
Question 14 of 25
As air pressure drops, in what range does the trailer supply valve close by itself?
- 0 to 69 kPa (0 to 10 psi)
- 552 to 690 kPa (80 to 100 psi)
- 138 to 311 kPa (20 to 45 psi)
- 690 to 828 kPa (100 to 120 psi)
Show answer
Answer: C. 138 to 311 kPa (20 to 45 psi)
The trailer supply valve pops out automatically between 138 and 311 kPa (20 and 45 psi).
Question 15 of 25
You find an air brake defect during your inspection. What does Ontario law say about driving the vehicle?
- It is illegal to drive a defective vehicle, and you must report the defect
- You may drive it if the load is light or the trailer is empty
- You may drive it if you drive carefully and below 50 km/h
- You may drive it for up to 7 days before getting it fixed
Show answer
Answer: A. It is illegal to drive a defective vehicle, and you must report the defect
Drivers must report defects, and it is illegal to drive a defective vehicle.
Question 16 of 25
How long do you watch the gauge during the air-loss rate test?
- 5 minutes
- 15 minutes
- 1 minute
- 10 seconds
Show answer
Answer: C. 1 minute
The air-loss test measures the pressure drop over one minute.
Question 17 of 25
What makes an air tank defective in the mechanical inspection?
- It is not securely mounted
- It has some water in it before draining
- It has a drain valve
- It is painted
Show answer
Answer: A. It is not securely mounted
Air tanks must be securely mounted.
Question 18 of 25
What are foundation brakes?
- The brake parts at each wheel, such as drums and shoes
- The concrete pads that trucks park on at terminals
- The brakes on the trailer's landing gear legs
- The engine brake that slows the vehicle on hills
Show answer
Answer: A. The brake parts at each wheel, such as drums and shoes
Foundation brakes are the wheel-mounted parts, such as drums or rotors and shoes or pads, worked by the air system.
Question 19 of 25
At about what pressure does the supply tank safety valve normally open?
- 690 kPa (100 psi)
- 552 kPa (80 psi)
- 1380 kPa (200 psi)
- 1035 kPa (150 psi)
Show answer
Answer: D. 1035 kPa (150 psi)
The safety valve protects the system from too much pressure. It normally opens at 1035 kPa (150 psi).
Question 20 of 25
During the build-up test, how long may it take for pressure to rise from 587 to 690 kPa (85 to 100 psi) at 600 to 900 rpm?
- No more than 10 seconds
- No more than 2 minutes
- No more than 5 minutes
- No more than 10 minutes
Show answer
Answer: B. No more than 2 minutes
If build-up from 587 to 690 kPa takes more than two minutes, the system is defective.
Question 21 of 25
How do you test the spring (parking) brakes' holding ability?
- With them applied, gently apply engine power and see if they hold
- Drain all the air tanks first, then try to roll the vehicle
- Drive at highway speed and pull the parking brake control
- Release the spring brakes and push the pedal hard
Show answer
Answer: A. With them applied, gently apply engine power and see if they hold
The spring brakes are defective if they do not hold the vehicle still when engine power is applied gently.
Question 22 of 25
Which brake drum condition is a defect?
- A crack or break in the drum
- A drum that is warm after driving
- Dust on the outside of the drum
- A drum painted black
Show answer
Answer: A. A crack or break in the drum
Inspect brake drums or rotors for cracks or breaks.
Question 23 of 25
According to the Ontario handbook, what is the highest allowed governor cut-out pressure?
- 1200 kPa (175 psi)
- 828 kPa (120 psi)
- 1000 kPa (145 psi)
- 1035 kPa (150 psi)
Show answer
Answer: C. 1000 kPa (145 psi)
The cut-out pressure must not be above 1000 kPa (145 psi).
Question 24 of 25
What is the difference between version 1 and version 2 of the air brake practical test?
- Version 2 is only for people who failed version 1 before
- Version 1 is for buses and version 2 is for straight trucks only
- Version 1 is given in English and version 2 is given in French
- Version 1 is for tractor-trailer air systems; version 2 is for other vehicles
Show answer
Answer: D. Version 1 is for tractor-trailer air systems; version 2 is for other vehicles
Version 1 covers vehicles with a tractor-trailer air brake system; version 2 covers vehicles without that system.
Question 25 of 25
In Ontario, which vehicles need a Z endorsement on your licence?
- Only tractor-trailers with a trailer over 4,600 kg
- Vehicles with air brakes or air-over-hydraulic brakes
- Only school buses and other passenger vehicles
- Any vehicle with anti-lock brakes, of any type
Show answer
Answer: B. Vehicles with air brakes or air-over-hydraulic brakes
You need a Z endorsement to drive any vehicle with air brakes or air-over-hydraulic brakes.

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