Engineering: Braking Systems

Historical Development of Braking Systems

• Contracting Band Brakes

• Drum Brake

• Disc Brake

• Anti Lock Braking System ( ABS )

• Exhaust and Engine

• Regnerative Braking System

• Automotive Hand Break

1. Contracting Band Brake

• In 1895, cars used contracting band brakes as pneumatic rubber tyrers made “block brakes” less effective

• Had “Servo-assistance”

Servo Assistance- Brakes naturally tried to increase braking force

Advantage

• Less damage of road debris

Disadvantage

• Heat caused the drum to expand and drag againsnt the band

• Not enough force for faster cars

Drum Brake

• The shoes are lined with a friction material such as woven asbestos or a pressed asbestos composite

• The shoes are enclosed in the drum, so the friction lining is away from water and dirt

• Also has servo assistance

• Hydraulically operated pistons opened the shoes, as the hydraulic cylinder was connected by piping to a master cylinder

DISADVANTAGE

• Poor heat dissipation, difficulty to remove heat

Disc Brake

• Most common type of brakes used in modern cars

• Offers better heat dissipation other than drum brake

• Offer wet weather performance as water is thrown off the disc by centrifugal force

• Ventillated Discs to improve heat dissipation

Disadvantage

• No servo-assistance, so that means the force at the pedal is very large. To reduce the effort the pedal force is boosted, a Vacum Booster is used.

Anti Lock Braking System (ABS) - More in Depth as a short answer question

• It is a safety system that prevents the wheels from locking up during heavy braking.

Locking up- Wheels wheel stops rotating even though the car is still moving

• It can lead to a loss of control and consequently accidents

MAIN INFO

• In order for wheels to not lock up, it is achieved by “wheel sensors and computer control over the braking circuit”

1. The wheel begins to lock up, the wheel sensor will detect

2. Send a message to the computer

3. The computer will realease hydraulic pressure and allow the wheel to spin again.

It says ABS sensors are also used for:

Traction control → controls wheel spin during acceleration

Dynamic stability control → helps with handling and cornering

Exhaust and Engine Brakes

Engine Braking: Engine will tend to retard (slow down) the veichle

Exhaust Braking: Involves constricting the exhaust system

Regenerative Braking System ( Short Answer)

• More environmentally friendly approach

• In hybrid cars, the motor drives a generator that provides electricity to an electric motor. They also use batteries so in city areas the petrol or diesel motor does not need to run.

• The advantage of this means that it is also possible to use electricity generation to slow the car.

The car’s kinetic energy is converted into useful electrical energy instead of being given off as heat energy.

ADVANTAGE

So instead of only using normal friction brakes:

the car can also slow down through electricity generation

Generator- Mechanical to Electric

Motor- Electric to Mechanical

Automotive Hand Brake

• To hold a veichle in a parked position

Environmental Implications from the use of materials in Braking System

• When asbestos breaks into tiny fibres, people can breathe them in. These fibres can get stuck in the lungs and may eventually cause lung cancer.

ASBESTOS