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

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

By using the spring brake control valve

By pumping the brake pedal repeatedly

By shutting off the engine

By turning on the headlights

2 / 30

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

Press the brake pedal while turning off the ignition

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

Turn the valve clockwise to release the spring brakes

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

3 / 30

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

The spring brakes start to apply automatically

The compressor shuts down immediately

The service brakes automatically release

The spring brakes fully release

4 / 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

5 / 30

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

To automatically adjust the brake shoes

To increase the force of the spring brake

To connect two chambers together

To manually compress and disable the spring brake

6 / 30

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

Buses and motor coaches

Light-duty pickup trucks

Passenger cars

Off-road construction equipment only

7 / 30

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

Only used on the front axle

Smaller because it uses less air

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

The same size and appearance

8 / 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

9 / 30

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

Foot-operated valve with a red round button

Handwheel valve located on the steering column

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

Floor-mounted toggle switch with a green knob

10 / 30

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

Parking-only chamber

Dual-diaphragm chamber

Spring brake chamber

Service-only chamber

11 / 30

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

Three

One

Four

Two

12 / 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 276 kPa (40 psi)

About 138 kPa (20 psi)

13 / 30

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

It is greatly increased

It remains unchanged

It only affects service brakes, not spring brakes

It is reduced

14 / 30

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

Inside the air dryer

Nearest the pushrod end

Farthest from the pushrod end

In the middle of the chamber

15 / 30

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

Turn off the spring brake control valve

Continue driving normally until the next scheduled service

Have the vehicle inspected and repaired immediately

Add more air pressure to reactivate the chamber

16 / 30

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

To adjust the parking brake

To apply the service brakes

To apply only the spring brakes

To control the air compressor

17 / 30

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

It causes the spring brakes to overheat

It makes the spring brakes apply too quickly

It improves spring brake stopping power

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

18 / 30

How are spring brakes applied?

They apply only when the vehicle is turned off

They apply when air pressure leaves the brake chamber

They apply only when the driver presses the brake pedal

They apply when air pressure builds up in the brake chamber

19 / 30

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

A trailer exhaust valve with a red lever

A cab suspension control with a green knob

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

A front axle lock valve with a white knob

20 / 30

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

By the absence of any air lines

By the visible protrusion of the caging bolt or similar mechanism

By the chamber being smaller in size

By the chamber being painted a different color

21 / 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 spring brakes will begin to apply automatically

The service brakes will automatically cool

The air compressor will stop working permanently

The engine will automatically shut down

22 / 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 is only decorative

Because the valve must be removed daily

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

23 / 30

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

By a mechanical means inside the chamber

By an electronic solenoid only

By a hydraulic locking device

By a large external coil spring

24 / 30

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

To make the compressor run faster

To disable the parking brake control valve

To prevent the service brakes from overheating

To keep the spring brakes from starting to apply

25 / 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

26 / 30

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

Disconnect and reconnect the air lines

Pump the brake pedal repeatedly for one minute

Turn off the ignition and restart the engine

Press the brake pedal for three to five seconds

27 / 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 chambers are too heavy to move

The spring is under very high tension and can release violently

28 / 30

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

The knob locks in the pushed-in position

The knob pops out

The knob becomes loose and spins

The knob changes color

29 / 30

What is a DD3 Safety Actuator?

A specialized front axle service brake

A device used only on trailers with hydraulic brakes

A type of air compressor governor

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

30 / 30

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

The service brakes cool down

The parking brake is fully released

The compressor stops building air

The spring brakes apply suddenly, causing an uncontrolled stop

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.