Brake Information & Brake Links at HealthHaven.com

This article is about the vehicle component. For other uses, see Brake (disambiguation).

A brake is a device that decelerates a moving object such as a machine or vehicle by converting its kinetic energy into another form of energy, or a device which prevents an object from accelerating.

Most commonly brakes use friction convert kinetic energy into heat, but in regenerative braking much of the energy is converted instead into useful electrical energy or potential energy (in the form of pressurized air).

Since kinetic energy increases quadratically with velocity ( $K = m v 2 / 2$ ), an object traveling at 10 kilometers per second takes 100 times more energy to stop than one traveling at 1 kilometer per second, and consequently the braking distance is 100 times as long.

Almost all wheeled vehicles have a brake of some sort. Even baggage carts and shopping carts may have them for use on a moving ramp. Most fixed-wing aircraft are fitted with wheel brakes on the undercarriage. Some aircraft also feature air brakes designed to reduce their speed in flight. Notable examples include gliders and some World War II-era aircraft, primarily some fighter aircraft and many dive bombers of the era. These allow the aircraft to maintain a safe speed in a steep descent. The Saab B 17 dive bomber used the deployed undercarriage as an air brake.

Friction brakes on automobiles store the heat in the drum brake or disc brake while braking then conduct it to the air gradually. When traveling downhill some vehicles can use their engines to brake.

When the brake is pushed the caliper containing piston pushes the pad towards the brake disc which slows the wheel down. On the brake drum it is similar as the cylinder pushes the brake shoes towards the drum which also slows the wheel down.

[edit] Noise

Brake lever on a horse-drawn hearse.

Main article: Roadway noise

Although ideally an brake would convert all the kinetic energy into heat, in practice a significant amount may be converted into acoustic energy instead, contributing to noise pollution.

For road vehicles, the noise produced varies significantly with tire construction, road surface, and the magnitude of the deceleration.^[1] Noise can be caused by different things. These are signs that there may be issues with brakes wearing out. Looking at http://www.braketeam-portland.com/braketeam/brakechange.html

[edit] Inefficiency

A significant amount of energy is always lost while braking, even with regenerative braking which is not perfectly efficient. Therefore a good metric of efficient energy use while driving is to note how much one is braking. If the majority of deceleration is from unavoidable friction instead of braking, one is squeezing out most of the service from the vehicle. Minimizing brake use is one of the fuel economy-maximizing behaviors.