Chapter 3: Service Brake Subsystem

The “Service Brake Subsystem” chapter in the Ontario air brake test manual highlights the main braking system used during regular driving.

Ontario Air Brake Test - Chapter 3: Service Brake Subsystem

1 / 25

In a dual-circuit air brake system, air is drawn from:

Only the secondary tank

A single combined tank

Only the primary tank

Both primary and secondary tanks

2 / 25

What are the brakes used for normal stopping on vehicles with air brakes called?

Service brakes

Emergency brakes

Spring brakes

Parking brakes

3 / 25

When air pressure is released from a service brake chamber, what returns the pushrod to its original position?

The slack adjuster

The parking brake mechanism

The spring inside the chamber

The driver pulling back the pedal

4 / 25

What happens to brake force when pushrod stroke exceeds the adjustment limit?

Brake force remains unchanged

Brake force moves to the steering axle only

Brake force drops significantly

Brake force increases excessively

5 / 25

In common brake designs, why can pushrod stroke length be measured?

The pushrod is monitored electronically only

Stroke length is always hidden inside the drum

Some brake linkage components are exposed

The chambers are transparent

6 / 25

What are the two kinds of air brake chambers mentioned?

Service and spring brake chambers

Front and rear chambers

Primary and secondary chambers

Drum and disc chambers

7 / 25

The front wheel-limiting valves (where used) have what function?

Lock the front wheels during braking

Disable the rear brakes when turning

Increase fuel delivery to the engine

Reduce the force of the service brakes on the front steering axle

8 / 25

When you press the brake pedal, what causes the pushrod in the brake chamber to move out?

Hydraulic fluid pressure

Compressed air filling the chamber and moving the diaphragm

A mechanical cable pulling on the rod

Gravity acting on the rod

9 / 25

What is a key rule regarding pushrod stroke?

You must not let the pushrod stroke exceed the adjustment limit

Stroke should be adjusted only when brakes are new

You must always set the stroke to the maximum possible

Stroke length does not need to be checked

10 / 25

What flexible component inside a service brake chamber moves when air pressure is applied?

Pushrod return spring

Diaphragm

Slack adjuster

Brake drum

11 / 25

What is the function of an air brake chamber?

Lubricate the brake components

Convert compressed air into mechanical force to apply the brakes

Store engine coolant

Control the vehicle’s electrical system

12 / 25

What does pressing the brake pedal directly control?

The fuel flow to the engine

The air pressure applied to the service brakes

The electrical system voltage

The parking brake application

13 / 25

What is the primary function of the brake pedal in an air brake system?

Apply the parking brakes only

Apply the service brakes

Release the spring brakes only

Control engine braking only

14 / 25

Why is it important to correctly identify brake type and chamber size?

To select the proper tire pressure

To determine the correct pushrod stroke-adjustment limit

To choose the correct engine oil

To adjust steering alignment

15 / 25

Why must brake linkage be readjusted as brakes wear?

To increase fuel economy

To change brake shoe type

To keep pushrod stroke within its normal operating range

To reduce air tank size

16 / 25

Brake hoses and tubes used in air brake systems must:

Be interchangeable regardless of size

Be the correct size and type

All be made from metal only

All be colourless

17 / 25

What is “pushrod stroke”?

The speed at which the wheels turn

The diameter of the brake drum

The amount of air in the reservoir

The distance the pushrod travels out of the brake chamber

18 / 25

Why is it critical that brakes are correctly adjusted?

Only to make the vehicle ride more smoothly

To prevent tire wear only

To ensure brake function is retained and legal requirements are met

To reduce engine noise

19 / 25

Who is allowed to perform brake re-adjustments on manual and automatic slack adjusters?

Only the vehicle owner

Any mechanic without specific certification

Only certified technicians

Any driver with a licence

20 / 25

What happens as the brake pedal is pressed harder?

The valve opens farther, increasing air pressure to the service brakes

The air compressor turns off

The parking brakes automatically apply

The valve closes, reducing air pressure to the brakes

21 / 25

How does increased application pressure (for example, from 69 kPa to 552 kPa) affect pushrod stroke?

The stroke decreases

The stroke increases noticeably

The stroke always remains the same

The stroke becomes zero

22 / 25

What component links the brake chamber pushrod to the brake assembly?

Slack adjuster

Brake pedal

Diaphragm

Brake hose

23 / 25

Why is a dual-circuit brake design used?

To increase fuel efficiency

To reduce the need for air compressors

So that if one circuit fails, the other circuit still operates some brakes

To eliminate the need for regular inspections

24 / 25

What is the purpose of brake hoses and tubes in an air brake system?

Circulate coolant in the engine

Transmit electrical signals to dash gauges

Deliver compressed air to all components of the air brake system

Deliver fuel to the engine

25 / 25

What are clamp-type brake chambers?

Chambers held together by a clamp assembly

Chambers that cannot be disassembled

Chambers made only of plastic

Chambers welded permanently

Your score is

This section explains how the service brakes work: air pressure applied to brake chambers activates the brakes on each wheel. It details key components such as brake pedals, chambers, push rods, and slack adjusters. Drivers are taught how to identify proper function, recognize warning signs of malfunction, and understand the importance of regular inspections. Mastering this chapter is essential for passing the Ontario air brake test and for ensuring safe, controlled stops when operating vehicles equipped with air brakes.