Brake Systems

Question 1

Which 3 factors define braking?

Answer 1

• The amount of pressure applied to the 2 surfaces
• The amount of surface area that is in contact with each other
• The type of material that is used to cause friction between the surfaces

Question 2

How do drum brakes function?

Answer 2

When the brake pedal is applied, hydraulic pressure presses the brake shoes or shoe pad against the drum, slowing down the wheels

Question 3

How to disc brakes function?

Answer 3

When the brake pedal is applied, the hydraulic pressure pushes the pistons in the calliper outwards, which squeeze the pads against the rotor to stop wheel motion

Question 4

Compare and contrast drum and disc brakes

Answer 4

Disc brakes generally have a better performance and heat dissipation which helps prevent brake fade

Drum brakes are cheaper to manufacture and maintain due to simpler design

Question 5

What is the ABS system?

Answer 5

A safety feature in a car which prevents wheel from locking up during braking

Question 6

How does the ABS system work?

Answer 6

• Sensors on all wheels monitor wheel speed
• ABS automatically applies and releases brakes on the wheel to prevent lockup
• The pumping action allows wheels to maintain traction with the road surface

Question 7

How do speed sensors regulate pressure in the ABS System?

Answer 7

• Monitor the speed of each wheel
• Sends wheel speed data to the ECU

Question 8

How do valves regulate pressure in the ABS system?

Answer 8

The control the flow of brake fluid to wheel

Question 9

How does a pump regulate pressure in the ABS?

Answer 9

• They open the valves to release pressure when the wheel is about to lock up
• They reapply pressure when wheel speed increases to prevent lock-up

Question 10

How does the ECU regulate pressure in the ABS system?

Answer 10

• Receives wheel speed data and detects potential lock-ups
• Decides when to reduce, hold or increase pressure depending on the state of the wheel

Question 11

What is regenerative braking?

Answer 11

• A system where kinetic energy stored during deceleration is transferred into another energy store for other uses
• When the brakes are applied, the motor acts as a generator. Kinetic energy is transferred to electrical energy to recharge the battery

Question 12

What are the pros regenerative braking?

Answer 12

Pros:
- Energy recovery: Prevents kinetic energy being lost as heat
- Reduced brake wear: eletric motor is used to reduce speed insetad of friction brakes
- Lower emissions: increased efficiency = lower emissions, less brake dust pollution due to reduced use of friciton brales

Cons:
- Limited braking power
- Increased vehicle cost
- Less effective on slippery surfaces

Question 13

What are the cons of regenerative braking?

Answer 13

• Limited power: can’t stop the vehicle alone
• High complexity and cost: additional components are required: motor, inverter, battery
• Less effective on slippery surfaces: Can cause wheel slip in low traction conditions