Chapter 4: Spring Brake Subsystem

The “Spring Brake Subsystem” chapter in the Ontario air brake test manual focuses on the emergency and parking brake functions of air brake systems.

Ontario Air Brake Test - Chapter 4: Spring Brake Subsystem

1 / 30

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

To control the air compressor

To adjust the parking brake

To apply only the spring brakes

To apply the service brakes

2 / 30

What happens to the spring brake control valve knob when the spring brakes apply automatically due to low air pressure?

The knob becomes loose and spins

The knob changes color

The knob pops out

The knob locks in the pushed-in position

3 / 30

How can the spring brakes be applied in an emergency when the service brakes fail?

By pumping the brake pedal repeatedly

By shutting off the engine

By turning on the headlights

By using the spring brake control valve

4 / 30

How is the brake locked in the applied position in a DD3 brake chamber?

By an electronic solenoid only

By a mechanical means inside the chamber

By a large external coil spring

By a hydraulic locking device

5 / 30

What is the purpose of a “caging bolt” in a spring brake chamber?

To connect two chambers together

To automatically adjust the brake shoes

To manually compress and disable the spring brake

To increase the force of the spring brake

6 / 30

How many air line connections does a DD3 brake chamber have?

Two

Three

One

Four

7 / 30

What happens to spring brake effectiveness if the foundation brakes are out of adjustment?

It only affects service brakes, not spring brakes

It is reduced

It remains unchanged

It is greatly increased

8 / 30

Compared to a regular service brake chamber, a spring brake chamber is:

Smaller because it uses less air

Only used on the front axle

The same size and appearance

Larger because it has an additional section to house the coil spring

9 / 30

How are spring brakes applied?

They apply only when the driver presses the brake pedal

They apply when air pressure builds up in the brake chamber

They apply when air pressure leaves the brake chamber

They apply only when the vehicle is turned off

10 / 30

On most vehicles, how is the spring brake control valve operated to release the spring brakes?

Pull the valve out to supply air and release the spring brakes

Press the brake pedal while turning off the ignition

Turn the valve clockwise to release the spring brakes

Push the valve in to supply air and release the spring brakes

11 / 30

What type of valve is normally used as the spring brake (parking and emergency) control valve?

Push/pull type valve with a yellow, four-sided knob

Handwheel valve located on the steering column

Foot-operated valve with a red round button

Floor-mounted toggle switch with a green knob

12 / 30

What is a DD3 Safety Actuator?

A type of parking and emergency brake chamber that does not use a large coil spring

A specialized front axle service brake

A type of air compressor governor

A device used only on trailers with hydraulic brakes

13 / 30

Why is it important to ensure there is enough air pressure before driving a vehicle with spring brakes?

To keep the spring brakes from starting to apply

To prevent the service brakes from overheating

To make the compressor run faster

To disable the parking brake control valve

14 / 30

What additional control might some trucks and tractors have for their parking brakes?

A trailer exhaust valve with a red lever

A tractor parking-brake control valve with a round blue knob

A cab suspension control with a green knob

A front axle lock valve with a white knob

15 / 30

When system pressure falls below its normal operating range (around 414 kPa or 60 psi), what is the key point drivers must remember?

The engine will automatically shut down

The service brakes will automatically cool

The air compressor will stop working permanently

The spring brakes will begin to apply automatically

16 / 30

Why must drivers be familiar with the type of spring brake control valve used in their vehicle?

Because it must be adjusted during driving

Because the valve must be removed daily

Because the valve is only decorative

Because some vehicles may use different types (push/pull or toggle) and functions

17 / 30

How can a driver recognize a disabled (caged) spring brake chamber?

By the visible protrusion of the caging bolt or similar mechanism

By the absence of any air lines

By the chamber being smaller in size

By the chamber being painted a different color

18 / 30

Which statement about the large coil spring inside a spring brake chamber is correct?

It is designed to be serviced by drivers

It is under low tension and safe to handle

It is under high tension and can be hazardous if it fails

It is only used on steer axle brakes

19 / 30

What is required to release the brakes on a DD3 system after operating the control valve?

Press the brake pedal for three to five seconds

Turn off the ignition and restart the engine

Disconnect and reconnect the air lines

Pump the brake pedal repeatedly for one minute

20 / 30

What is the name of a brake chamber that includes both service brake and spring brake sections?

Service-only chamber

Parking-only chamber

Spring brake chamber

Dual-diaphragm chamber

21 / 30

What occurs when the spring brake control valve exhausts the air holding the spring brakes released?

The parking brake is fully released

The service brakes cool down

The spring brakes apply suddenly, causing an uncontrolled stop

The compressor stops building air

22 / 30

How much air pressure is normally required to release (compress or “cage”) the spring in a spring brake chamber?

About 690 kPa (100 psi)

About 414 kPa (60 psi)

About 138 kPa (20 psi)

About 276 kPa (40 psi)

23 / 30

Why should drivers never attempt to service or repair any air brake chamber containing a large coil spring?

The chambers contain flammable fluid

The chambers are sealed with permanent glue

The spring is under very high tension and can release violently

The chambers are too heavy to move

24 / 30

What happens when system air pressure drops below about 414 kPa (60 psi)?

The service brakes automatically release

The spring brakes fully release

The spring brakes start to apply automatically

The compressor shuts down immediately

25 / 30

Where is the service brake section located on a spring brake chamber?

Farthest from the pushrod end

Nearest the pushrod end

In the middle of the chamber

Inside the air dryer

26 / 30

What does the spring brake control valve do automatically when system pressure drops below about 414 kPa (60 psi)?

It shuts down the engine

It increases air supply to the service brakes

It exhausts the remaining air holding the spring brakes released

It opens the air dryer purge valve

27 / 30

What is the primary purpose of spring brakes on vehicles with air brakes?

To replace the need for regular brake inspections

To increase fuel efficiency during highway driving

To provide parking and emergency braking if the service brake system fails

To cool the service brakes during long downhill runs

28 / 30

On what types of vehicles are DD3 brake chambers commonly found?

Buses and motor coaches

Passenger cars

Light-duty pickup trucks

Off-road construction equipment only

29 / 30

What should a driver do after noticing a disabled spring brake chamber?

Continue driving normally until the next scheduled service

Turn off the spring brake control valve

Add more air pressure to reactivate the chamber

Have the vehicle inspected and repaired immediately

30 / 30

What effect does poor brake adjustment have on spring brake performance?

It reduces the ability of spring brakes to stop or hold a vehicle

It makes the spring brakes apply too quickly

It improves spring brake stopping power

It causes the spring brakes to overheat

Your score is

Spring brakes automatically engage when air pressure drops to a dangerous level, ensuring the vehicle can be safely stopped even if the main system fails. This chapter explains the components involved, such as the spring brake chambers and parking brake controls, and their role in vehicle safety. Understanding how to properly use, test, and maintain spring brakes is crucial for passing the Ontario air brake test and for preventing unintentional vehicle movement, especially on inclines or during emergencies.