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 trailer fails the automatic spring brake application test if:

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

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

The low air-pressure warning activates

The tractor protection valve closes

2 / 35

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

The vehicle may roll several meters

The vehicle must not move or rock at all

The vehicle may move freely if on level ground

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

3 / 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

4 / 35

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

At or above 380 kPa (55 psi)

Exactly 300 kPa (44 psi)

Only above 900 kPa (130 psi)

Below 345 kPa (50 psi)

5 / 35

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

Tire pressure

Weather conditions

Engine temperature

Body design and suspension

6 / 35

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

It allows operation at reduced speed only

It allows operation if the trailer is empty

It allows operation during daylight hours only

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

7 / 35

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

The spring brakes must be caged

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

The tanks must be completely empty

The trailer must be disconnected

8 / 35

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

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

To test the low‑pressure warning device

To warm up the system

To increase system pressure quickly

9 / 35

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

That the low‑pressure warning sounds

That air pressure increases

That the spring brakes release

That each drain valve functions properly and discharge is observed

10 / 35

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

They must operate silently

They must reduce stopping distance

They must release quickly

They must hold the vehicle in place

11 / 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:

Less than one minute

Greater than two minutes

Equal to the low‑pressure cut‑in time

Exactly ninety seconds

12 / 35

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

Both at the same time

The towing vehicle’s spring brakes

The steering axle only

The trailer’s spring brakes

13 / 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 engine speed increases

The parking brake light remains on

14 / 35

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

Only the supply tank drains moisture

The trailer supply valve stays open

No discharge from any drain valve

Each drain valve functions properly

15 / 35

A vehicle fails the tractor protection valve test if:

The air‑pressure warning activates

Air exhausts from the trailer service line during the test

The service brakes build pressure quickly

The trailer supply valve is pulled out

16 / 35

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

It must be drained more often

It must be closed permanently

It must be repaired

It must be bypassed with a hose

17 / 35

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

Apply and release the parking brake repeatedly

Turn the engine off and observe the gauges

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

Disconnect the service line only

18 / 35

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

Any tank discharges air

The supply tank discharges moisture

The warnings lights turn off

Any drain valve fails to function properly

19 / 35

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

By increasing air pressure

By applying maximum engine power

By reducing air pressure

By draining only the trailer tanks

20 / 35

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

A steady stream of air exhausting

Air exhausting only when the spring brakes are applied

No air exhausting from the trailer service line

Air exhausting only when the engine is off

21 / 35

Which tank should always be drained first?

The rear service tank

The trailer reservoir tank

The supply tank

The front service tank

22 / 35

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

When body design and suspension limit access

When the air pressure is above cut‑out

When the temperature is below freezing

When the vehicle is empty

23 / 35

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

The trailer service line begins exhausting air

The low air-pressure warning activates

The trailer moves slightly when power is applied

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

24 / 35

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

It allows operation if the vehicle is empty

It allows operation at night only

It allows operation within city limits only

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

25 / 35

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

Normal compressor operation

Excessive brake lining wear

Risk of air brake system contamination that must be reported

Low governor cut‑in pressure

26 / 35

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

It means the tanks no longer need draining

It should be noted but no action is required

It should be ignored if brakes seem normal

It must be reported and repaired

27 / 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 apply only when the service brakes are applied

They must release automatically

They must apply automatically

28 / 35

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

To increase air pressure in the trailer tanks

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

To reduce brake wear on the trailer

To automatically adjust air‑tank drain intervals

29 / 35

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

It must be turned off at the dashboard fuse

It must be closed (pulled out)

It must be opened (pushed in)

It must be partially opened

30 / 35

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

In the supply tank

In the rear service tank only

In all air tanks equally

In the trailer spring brake chamber

31 / 35

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

Only the location of the supply tank

The location of all air tanks and drains

Only the location of the trailer tanks

Only the number of tanks, not their locations

32 / 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

Ten minutes

Five minutes

Two minutes

33 / 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

34 / 35

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

The secondary service tank

The primary service tank

The supply tank

The trailer reservoir only

35 / 35

Why must air tanks be drained regularly?

To reduce fuel consumption

To increase governor cut‑out pressure

To cool the brake system

To remove accumulated moisture and oil and check for abnormalities

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.