| The sound of screeching tires may be one of the | | | | braking hard on wet or slippery surfaces. By |
| most annoying things you get to hear on the | | | | 1990, ABS was available on about 25 percent of |
| streets. However, for some people, the violent | | | | all new cars and trucks. Today, ABS is available |
| screech of tires and the nauseous whiff of brake | | | | on over 90 percent of all new vehicles. |
| fluid can mean something totally different: that | | | | Other Braking Systems |
| their brakes are doing their job of keeping | | | | In 1869, George Westinghouse invented a |
| passengers safe from a collision. | | | | different system of applying brakes. Instead of |
| Brakes are devices that are used to slow rotating | | | | using liquid pressure to apply the brakes, he used |
| wheels until they stop. Friction brakes are the | | | | a system wherein it is the air pressure that |
| most common examples of such brakes. Brakes | | | | prevents the brakes from applying. |
| like the ones used on everyday vehicles such | | | | This is helpful since the Achilles heel of hydraulic |
| automobiles, bicycles, trucks and trains use friction | | | | brakes is that when there is a loss of pressure, |
| between brake pad and a wheel to slow the | | | | the brakes become ineffective. In Westinghouse's |
| motion of a vehicle. | | | | system, when there is loss of air pressure, the |
| However, the friction created by the brakes | | | | brakes automatically apply. |
| generates a great deal of heat. The brake | | | | This is a safer alternative that is useful in high-load |
| system should be able to dissipate this heat or | | | | transportation such as trains. |
| else the brake could lose its efficacy. | | | | Large, heavy-duty trucks, as well as buses and |
| There are many kinds of brakes - the most | | | | trains, use compressed air pressure rather than |
| common of which are the ones used in | | | | hydraulic fluid to operate their brakes. |
| automobiles: the disc and drum brakes. Both, | | | | Tomorrow's Brakes |
| however, rely on hydraulics, or the use of brake | | | | While we still mostly rely on friction for braking, |
| fluid pressure to activate the brakes. | | | | many technological advances call for new braking |
| The drum brakes work by the constriction of | | | | methods. |
| brake shoes installed on the inside of the wheel. | | | | For example aircraft also use spoilers, and flaps to |
| The friction generated by this action slows the | | | | slow its velocity through the air. |
| motion of the vehicle. | | | | Electric cars and other electric vehicles use drum |
| The disc brake works by clamping the rotors of | | | | and disc brakes to stop, but some vehicles also |
| the wheel itself. Disc brakes are superior to drum | | | | make use of magnetic brakes, which create |
| brakes due to the fact that disc brakes are not | | | | opposing magnetic fields to resist motion. This |
| prone to malfunction even when wet or | | | | type of braking is called regenerative braking. This |
| immersed in water. This malfunction is called | | | | technique recaptures some of the vehicle's |
| brake fade. Disc brakes can also handle higher | | | | momentum as electrical energy. Regenerative |
| braking temperatures and dissipate heat more | | | | braking uses the magnets within the electric |
| quickly. Also, disc brakes do not trap water as | | | | motor itself to slow the vehicle. When the driver |
| drum brakes can. | | | | releases the accelerator pedal, the electric motor |
| In 1985, the first antilock brake system (ABS) | | | | changes into a generator, thus recapturing the |
| was introduced for motor vehicles in the United | | | | energy from the moving car and transforming it |
| States. ABS works as a safety feature to give | | | | back into electricity |
| drivers more control when braking. ABS has a | | | | As transportation becomes faster, safety |
| microprocessor and individual wheel-speed sensors | | | | becomes a primary concern. More powerful |
| that monitors the brakes of a vehicle. The | | | | means of controlling speed are needed, and the |
| hydraulic control valves for each brake circuit | | | | evolution of braking systems is not far off. |
| prevent skidding during panic stops or when | | | | |