Saturday, May 31, 2008

An automobile, usually called a car (an old word for carriage) or a truck, is a wheeled vehicle that carries its own engine. (Older terms include motor car, with "motor" referring to what is now usually called the engine, and horseless carriage.) It has seats for the driver and, almost without exception, for at least one passenger.

Table of contents
1 General
2 History
3 Safety
4 Renewable energy and the future
5 Major possible subsystems

The vehicle is designed to travel on roads, although some, notably sport utility vehicles, allow off-road driving. Roads and highways are shared with other traffic such as motorcycles, tractor trailers, and farm implements.

The typical vehicle has just an internal combustion engine and four wheels, although as of 2001, gas-electric hybrid engine-powered cars have begun to enter the market. Other vehicles run on electricity and fuel cells. Three-wheeled automobiles have been built, but are not common due to stability problems. Some gyrocar, two wheeled automobiles have been built as well, using gyroscopic stabilization.

Automobiles/cars come in configurations such as

Bubble car
Sports coup
Coupé convertible
Station wagon or Estate car
Sport utility vehicles (SUVs)
Pickup trucks
Truck (or lorry)
Van and minivan.

See car classification.

The first vehicles were steam engine powered, then electric vehicles were produced by a small number of manufacturers. Later on gasoline (petrol) and diesel engines were implemented.

Steam-powered self propelled vehicles were devised in the late 18th century. Nicolas-Joseph Cugnot successfully demonstrated such a vehicle as early as 1769.

Cugnot's invention initially saw little application in his native France, and the center of innovation passed to Britain, where Richard Trevithick was running a steam-carriage in 1801. Such vehicles enjoyed a vogue for a time, and over the next decades such innovations as hand brakes, multi-speed transmissions, and improved speed and steering were developed. Some were commercially successful in providing mass transit, until a backlash against these large speedy vehicles resulted in passing laws that self-propelled vehicles on public roads in Britain must be proceeded by a man on foot waving a red flag and blowing a horn (!). This effectively killed road auto development in the UK for most of the rest of the 19th century, as inventors and engineers shifted their efforts to improvements in railway locomotives. The red flag law was not repealed until 1896.

It is generally claimed that the first automobiles with gasoline powered internal combustion engines were completed almost simultaneously in 1886 by German inventors working independently, Gottlieb Daimler on 3 July 1886 in Mannheim and later Karl Benz and Wilhelm Maybach in Stuttgart. The major breakthrough came with the historic drive of Berta Benz in 1888. Steam, electric, and gasoline powered autos competed for decades, with gasoline internal combustion engines achieving dominence in the 1910s.

The first automobile patent in the United States was granted to Oliver Evans in 1789; in 1804 Evens demonstrated his first successful self-propelled vehicle, which not only was the first automobile in the USA but was also the first amphibious vehicle, as his steam-powered vehicle was able to travel on wheels on land and via a paddle wheel in the water. On November 5, 1895, George B. Selden was granted a United States patent for a two-stroke automobile engine. This patent did more to hinder than encourage development of autos in the USA until it was overturned on a challenge by Henry Ford.

The large scale, production-line manufacturing of affordable automobiles was debuted by Oldsmobile in 1902, then greatly expanded by Henry Ford in the 1910s. Early automobiles were often referred to as 'horseless carriages', which gives some idea of their design. Through the period from 1900 to the mid 1920s, development of automotive technology was rapid, due in part to a huge (hundreds) number of small manufacturers all competing to gain the world's attention. Key developments included electric ignition and the electric self-starter (both by Charles Kettering, for the Cadillac Motor Company in 1910-1911), independent suspension, and four-wheel brakes.

By roughly 1930, most of the technology used in automobiles had been invented, although is was often re-invented again at a later date and credited to someone else. For example, front-wheel drive was re-introduced by Andre Citroën with the launch of the Traction Avant in 1934, though it appeared several years earlier in road cars made by Alvis and Cord, and in racing cars by Miller (and may have appeared as early as 1897). After 1930, the number of auto manufacturers declined sharply as the industry consolidated and matured. Since 1960, the number of manufacturers has remained virtually constant, and geniune innovation slowed. For the most part, "new" automotive technology was a refinement on earlier work, though these refinements were sometimes so extensive as to render the original work nearly unrecognizable. The chief exception to this is electronic engine management, which only appeared in the 1960s with the advent of electronic parts that were cheap enough to be mass-produced and rugged enough to handle the harsh automobile environment. Developed by Bosch, these electronic systems have enabled automobiles to drastically reduce exhaust emissions while increasing efficiency and power.

In 1965, in California, legislation was introduced to regulate exhaust emissions, the first such legislation in the world. Answering this new interest in environmental and public safety issues, the Department of Transportation (DOT) and the Environmental Protection Agency (EPA) both introduced legislation in 1968 which substantially altered the course of automotive development. Since the US market was the largest in the world (and California was the largest in the US), manufacturers worldwide were forced to adapt. For the first time, safety devices were mandatory, as were controls on harmful emissions. Prior to this legislation, even seat belts were considered extra-cost options by many manufacturers. Other countries introduced their own safety and environmental legislation. In time, meeting regulations became the main challenge for the engineers designing new cars. In the decade from 1975 to 1985, all of the world's manufacturers struggled to meet the new regulations, often producing mediocre to awful cars with reduced reliability. However, by the end of this period, everyone had learned how to handle the new heavily regulated environment. The manufacturers discovered that safety and environmentalism sold cars, and began introducing some safety advances on their own.

Among these advances are the so-called alternative fuels for the internal combustion engine, which have been around for many years. Early in automotive history, before gasoline was widely available at corner pumps, cars ran on many fuels, including kerosine (aka paraffin) and coal gas. Alcohol fuels were used in racing cars before and just after WWII. Today, methanol and ethanol (alcohols) are used as petrol extenders in some countries, notably in Australia and the United States. In countries with warmer climate, such as Brazil, alcohol derived from sugar cane is often used as a fuel on its own.

In many countries, plentiful supplies of natural gas have seen methane sold as compressed natural gas (CNG) and propane sold as liquified petroleum gas (LPG) alongside petrol and diesel fuels since the 1970s. While a standard automotive engine will run on these fuels with very low exhaust emissions, there are some performance differences, notably a loss of power, due to the lower energy content of the alternative fuels. The need to equip filling stations and vehicles with pressure vessels to hold these gaseous fuels and the more stringent safety inspections means that they are only economical in high mileage vehicles or if there are installation incentives. They are most economical where petrol has high taxes and the alternative fuels do not.

The many varieties of automobile racing (also called motorcar racing) collectively constitute one of the most popular categories of sport in the world.

Accidents seem as old as automobile vehicles themselves. Joseph Cugnot crashed his steam-powered "Fardier" against a wall in 1770. The first recorded automobile fatality was Bridget Driscoll in August 17, 1896 in London, England.

Every year more than a million people are killed and about 50 million people are wounded in traffic (according to WHO estimates), either by crashing into something, or by being crashed into. Major factors in accidents include driving under the influence of alcohol or other drugs, inattentive driving, overtired driving, road hazards such as snow, potholes and animals, and reckless driving. Special safety features have been built into cars for years (some for the safety of car's occupants only, some for the safety of others):

ABS, Anti-lock Braking System, which prevents the car from skidding
Airbags, which inflate in a crash to cushion the blow of a head on the dashboard
Electronic Stability Program, ESP.
crumple zones, which buffers the impact when the car hits something
seat belts (or safety belts), which keep a person from being thrown forward
cage construction

There are standard tests for safety in new automobiles, like the EuroNCAP. Despite these technological advances, the death toll of car accidents remains high: about 40,000 people die every year in the US, a number which increases annually in line with rising population and increased travel (although the rate per capita and per mile travelled decreases steadily), and a similar number in Europe. The death toll is expected to nearly double worldwide by 2020. A much higher number of accidents result in permanent disability.
See also Car safety, Unsafe at Any Speed by Ralph Nader

Renewable energy and the future
With heavy taxes on fuel, particularly in Europe and tightening environmental laws, particularly in California USA, and the possibility of further restrictions on greenhouse gas emissions, work on alternative power systems for vehicles continues.

Diesel-powered cars can run with little or no modification on 100% pure biodiesel, a fuel that can be made from vegetable oils. Many cars that currently use gasoline can run on ethanol, a fuel made from plant sugars. Most cars that are designed to run on gasoline are capable of running with 15% ethanol mixed in, and with a small amout of redesign, gasoline-powered vehicles can run on ethanol concentrations as high as 85%. All petrol fueled cars can run on LPG.

Attempts at building viable battery-powered electric vehicles continued throughout the 1990s (notably General Motors with the EV1), but cost, speed and inferior driving range made them unviable.

Current research and development is centred on "hybrid" vehicles that use both electric and combustion (pollution) power, and longer-term efforts are based around electric vehicles powered by fuel cells.

Other alternatives being explored involve methane and hydrogen-burning vehicles, fuel cells, and even the stored energy of compressed air (see Air Engine).

Major possible subsystems

carburetor or fuel injection
fuel pump
engine configuration: rotary or reciprocating (V, inline, flat).
engine management systemss
exhaust system
ignition system
self starter
pollution control devices
turbo-chargers and superchargers
front engine
rear engine
mid engine

transmission (gearbox)
manual transmission
automatic transmission
2 Wheel Drive
4 Wheel Drive
limited slip differential
Live axle

disc brakes
drum brakes
anti-lock braking systems (ABS)

wheels and tires
custom wheels

rack and pinion
Ackermann steering geometry
Castor angle
Camber angle

MacPherson strut
double wishbone
torsion beam
semi-trailing arm

crumple zones
monocoque (or unibody) construction
suicide doors

interior equipment
passive safety
seat belts
child safety locks
ancillary equipment such as stereos, air conditioning, cruise control, positioning systems, cup holders, etc.

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