Chapter 10b: Inspecting Air Brake System Operation

An Ontario air brake practice test covering the chapter “Inspecting Air Brake System Operation” is a valuable study tool for aspiring commercial drivers.

Ontario Air Brake Test - Chapter 10b: Inspecting Air Brake System Operation

1 / 35

A vehicle fails the tractor protection valve test if:

Air exhausts from the trailer service line during the test

The service brakes build pressure quickly

The trailer supply valve is pulled out

The air‑pressure warning activates

2 / 35

When testing the tractor protection valve, what must be done with the trailer supply valve?

It must be opened (pushed in)

It must be closed (pulled out)

It must be turned off at the dashboard fuse

It must be partially opened

3 / 35

A trailer fails the automatic spring brake application test if:

The low air-pressure warning activates

The tractor protection valve closes

The trailer spring brakes do not apply when the trailer supply valve is closed

The air‑pressure build‑up time is less than two minutes

4 / 35

How must a trailer’s spring brakes behave when the trailer is disconnected from the towing vehicle?

They must stay in the same position

They must release automatically

They must apply automatically

They must apply only when the service brakes are applied

5 / 35

What is considered abnormal and must be reported when draining the remaining air tanks (not the supply tank)?

A slight hissing sound

No air discharge at all

A small amount of moisture discharge

A significant quantity of moisture being discharged

6 / 35

A vehicle fails the air‑tank drain valve test when:

Any drain valve fails to function properly

The warnings lights turn off

Any tank discharges air

The supply tank discharges moisture

7 / 35

What is the reason for always draining the supply tank first?

To test the low‑pressure warning device

To increase system pressure quickly

To warm up the system

To prevent accumulated moisture in the supply tank from passing farther into the system

8 / 35

An air brake system is considered defective if the air‑pressure build‑up time from 587 to 690 kPa (85 to 100 psi) is:

Equal to the low‑pressure cut‑in time

Less than one minute

Exactly ninety seconds

Greater than two minutes

9 / 35

On some vehicles, what may limit safe access to air tanks and drains?

Body design and suspension

Tire pressure

Weather conditions

Engine temperature

10 / 35

When testing low air‑pressure warning devices, how must the device be activated?

By draining only the trailer tanks

By applying maximum engine power

By increasing air pressure

By reducing air pressure

11 / 35

How should a sudden increase in the amount of moisture or oil drained from any tank be handled?

It should be noted but no action is required

It means the tanks no longer need draining

It must be reported and repaired

It should be ignored if brakes seem normal

12 / 35

Which tank should always be drained first?

The rear service tank

The supply tank

The trailer reservoir tank

The front service tank

13 / 35

Finding oil in any air tank other than the supply tank indicates:

Low governor cut‑in pressure

Risk of air brake system contamination that must be reported

Normal compressor operation

Excessive brake lining wear

14 / 35

When testing spring (parking and emergency) brakes, what is their required capability?

They must release quickly

They must operate silently

They must hold the vehicle in place

They must reduce stopping distance

15 / 35

At what pressure must the low air‑pressure warning device activate to be considered acceptable?

Below 345 kPa (50 psi)

Exactly 300 kPa (44 psi)

Only above 900 kPa (130 psi)

At or above 380 kPa (55 psi)

16 / 35

Which vehicle is preferable for performing the spring brake holding test when using a towing vehicle and trailer?

The towing vehicle’s spring brakes

The steering axle only

Both at the same time

The trailer’s spring brakes

17 / 35

How are spring brakes tested for holding power?

By fully releasing the spring brakes and coasting

By rapidly pumping the brake pedal

By gently applying engine power in a low gear while the spring brakes are applied

By checking the air gauge only

18 / 35

What is the main purpose of the tractor protection valve on a towing vehicle?

To reduce brake wear on the trailer

To prevent loss of air from the towing vehicle if there is an air‑loss problem in the trailer

To automatically adjust air‑tank drain intervals

To increase air pressure in the trailer tanks

19 / 35

Under what conditions might safe access to the air tanks and drains require a hoist, pit, or ramp?

When the vehicle is empty

When body design and suspension limit access

When the temperature is below freezing

When the air pressure is above cut‑out

20 / 35

What must be done with any malfunctioning air‑tank drain valve?

It must be repaired

It must be closed permanently

It must be bypassed with a hose

It must be drained more often

21 / 35

In the spring brake holding test, what indicates a failure?

The spring brakes do not hold the vehicle in place

The vehicle rocks slightly but does not move

The parking brake light remains on

The engine speed increases

22 / 35

During the air‑tank drain valve test, what must be observed for each tank?

That air pressure increases

That each drain valve functions properly and discharge is observed

That the spring brakes release

That the low‑pressure warning sounds

23 / 35

Which tank is expected to have some moisture, possibly a significant quantity, even when drained regularly?

The supply tank

The trailer reservoir only

The secondary service tank

The primary service tank

24 / 35

What is the recommended method to test the automatic application of trailer spring brakes?

Close (pull out) the trailer supply valve after the trailer is fully charged

Disconnect the service line only

Turn the engine off and observe the gauges

Apply and release the parking brake repeatedly

25 / 35

During the tractor protection valve test, what should you observe at the disconnected trailer service-line coupler if the valve is functioning properly?

Air exhausting only when the engine is off

A steady stream of air exhausting

No air exhausting from the trailer service line

Air exhausting only when the spring brakes are applied

26 / 35

What indicates a pass in the air‑tank drain valve test?

The trailer supply valve stays open

Each drain valve functions properly

Only the supply tank drains moisture

No discharge from any drain valve

27 / 35

What does the Ontario Highway Traffic Act say about operating a vehicle with a defective tractor protection valve?

It prohibits operation of a vehicle with a defective tractor protection valve

It allows operation at reduced speed only

It allows operation during daylight hours only

It allows operation if the trailer is empty

28 / 35

What is the acceptable maximum air‑pressure build‑up time from 587 to 690 kPa (85 to 100 psi) at 600–900 rpm?

One minute

Two minutes

Five minutes

Ten minutes

29 / 35

Why must air tanks be drained regularly?

To reduce fuel consumption

To increase governor cut‑out pressure

To remove accumulated moisture and oil and check for abnormalities

To cool the brake system

30 / 35

What does the Ontario Highway Traffic Act say about operating a vehicle with defective air‑tank drain valves?

It allows operation at night only

It allows operation if the vehicle is empty

It allows operation within city limits only

It prohibits the operation of a vehicle with defective air‑tank drain valves

31 / 35

Where might a small amount of oil be acceptable, though any visible quantity should be reported or repaired?

In the trailer spring brake chamber

In the supply tank

In all air tanks equally

In the rear service tank only

32 / 35

When testing air‑tank drain valves, what initial condition must be met?

The tanks must be completely empty

The air brake system must be within its normal operating pressure range

The trailer must be disconnected

The spring brakes must be caged

33 / 35

When testing automatic trailer spring brake application, what indicates a pass?

The low air-pressure warning activates

The trailer service line begins exhausting air

The trailer spring brakes apply automatically when the trailer supply valve is closed

The trailer moves slightly when power is applied

34 / 35

During the spring brake holding test, what vehicle behavior is acceptable?

The vehicle may rock and shake and the wheels may move slightly

The vehicle must not move or rock at all

The vehicle may move freely if on level ground

The vehicle may roll several meters

35 / 35

What must drivers know regarding the air tanks and drains on their vehicle?

Only the location of the trailer tanks

Only the number of tanks, not their locations

Only the location of the supply tank

The location of all air tanks and drains

Your score is

This practice test emphasizes essential procedures, such as checking for air pressure buildup, ensuring that warning signals activate at the correct levels, and assessing the operation of the service and parking brakes. By simulating real exam questions, the practice test helps users become familiar with typical scenarios and testing formats. Regular practice enhances understanding and confidence, making it easier to identify potential issues in the actual air brake system. Ultimately, these tests prepare drivers to perform safe, thorough inspections required by Ontario regulations.