forging new generations of engineers. brakes friction & braking friction: a force that opposes...

Forging new generations of engineers

Brakes

Friction & Braking

• Friction: A force that opposes motion, it prevents the sliding between two surfaces that are in contact.

• Amount of friction depends upon:– surface material– surface finish– force, acting upon the surfaces

• By using friction, brakes slow down or stop a rotating object.

Braking Action

• Brakes slow down a moving object by converting the kinetic energy of motion into another form.

• Most braking systems convert this kinetic energy into heat.

• The brake is cooled by moving air.

• If a brake becomes too hot, it will begin to lose its efficiency. This is called fade.

• Good brake design includes methods for adequate cooling of the brakes.

Brakes

• There are many different types of braking systems. Some of the more common types are:– Disc– Mechanical– Hydraulic– Pneumatic

Disc Brakes

• A friction pads is pressed against both sides of a rotating disc.

• This type of brake is commonly found on the front wheels of cars.

• They have good air flow around the brake which quickly dissipates heat.

Disc Brake

Mechanical Brakes

• Braking action is applied by physical force without the aid of hydraulics or pneumatics.

Hydraulics & Pneumatics

• Hydraulic and Pneumatic systems are closely related. Both use cylinders to produce a linear motion at varying speeds and forces.

• Hydraulics uses a fluid, hydraulic oil.• Pneumatics uses air.• Advantage of hydraulics is that oil can’t be

compressed.

Hydraulic - Pneumatic System

Hydraulic Brake