Automobile Systems
Automobiles are powered and
controlled by a complicated interrelationship between several systems. This
diagram shows the parts of a car with a gas engine and manual transmission (the
air filter and carburetor have been removed to show the parts beneath but
usually appear in the space above the intake manifold). The major systems of
the automobile are the power plant, the power train, the running gear, and the
control system. Each of these major categories include a number of subsystems,
as shown here. The power plant includes the engine, fuel, electrical, exhaust,
lubrication, and coolant systems. The power train includes the transmission and
drive systems, including the clutch, differential, and drive shaft. Suspension,
stabilizers, wheels, and tires are all part of the running gear, or support
system. Steering and brake systems are the major components of the control
system, by which the driver directs the car.
Automobile, self-propelled vehicle used
primarily on public roads but adaptable to other surfaces. Automobiles changed
the world during the 20th century, particularly in the United States and other industrialized
nations. From the growth of suburbs to the development of elaborate road and
highway systems, the so-called horseless carriage has forever altered the
modern landscape. The manufacture, sale, and servicing of automobiles have
become key elements of industrial economies. But along with greater mobility
and job creation, the automobile has brought noise and air pollution, and
automobile accidents rank among the leading causes of death and injury
throughout the world. But for better or worse, the 1900s can be called the Age
of the Automobile, and cars will no doubt continue to shape our culture and
economy well into the 21st century.
Automobiles are classified by size, style, number
of doors, and intended use. The typical automobile, also called a car, auto,
motorcar, and passenger car, has four wheels and can carry up to six people,
including a driver. Larger vehicles designed to carry more passengers are
called vans, minivans, omnibuses, or buses. Those used to carry cargo are
called pickups or trucks, depending on their size and design. Minivans are
van-style vehicles built on a passenger car frame that can usually carry up to
eight passengers. Sport-utility vehicles, also known as SUVs, are more rugged
than passenger cars and are designed for driving in mud or snow.
Auto manufacturing plants in 40 countries
produced a total of 63.9 million vehicles, including 42.8 million passenger
cars, in 2004, according to Ward’s Auto, an auto industry analyst. About 16.2
million vehicles, including 6.3 million passenger cars, were produced in North
America in 2004. For information on the business of making cars, see Automobile
Industry.
The automobile is built around an
engine. Various systems supply the engine with fuel, cool it during operation,
lubricate its moving parts, and remove exhaust gases it creates. The engine
produces mechanical power that is transmitted to the automobile’s wheels
through a drivetrain, which includes a transmission, one or more driveshafts, a
differential gear, and axles. Suspension systems, which include springs and
shock absorbers, cushion the ride and help protect the vehicle from being
damaged by bumps, heavy loads, and other stresses. Wheels and tires support the
vehicle on the roadway and, when rotated by powered axles, propel the vehicle
forward or backward. Steering and braking systems provide control over
direction and speed. An electrical system starts and operates the engine,
monitors and controls many aspects of the vehicle’s operation, and powers such
components as headlights and radios. Safety features such as bumpers, air bags,
and seat belts help protect occupants in an accident.
II
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POWER SYSTEM
|
Gasoline internal-combustion engines power most
automobiles, but some engines use diesel fuel, electricity, natural gas, solar
energy, or fuels derived from methanol (wood alcohol) and ethanol (grain
alcohol).
Most gasoline engines work in the following
way: Turning the ignition key operates a switch that sends electricity from a
battery to a starter motor. The starter motor turns a disk known as a flywheel,
which in turn causes the engine’s crankshaft to revolve. The rotating
crankshaft causes pistons, which are solid cylinders that fit snugly inside the
engine’s hollow cylinders, to move up and down. Fuel-injection systems or, in
older cars, a carburetor deliver fuel vapor from the gas tank to the engine
cylinders.
The pistons compress the vapor inside
the cylinders. An electric current flows through a spark plug to ignite the
vapor. The fuel mixture explodes, or combusts, creating hot expanding gases
that push the pistons down the cylinders and cause the crankshaft to rotate.
The crankshaft is now rotating via the up-and-down motion of the pistons,
permitting the starter motor to disengage from the flywheel.
A
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Engine
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The basic components of an
internal-combustion engine are the engine block, cylinder head, cylinders, pistons,
valves, crankshaft, and camshaft. The lower part of the engine, called the
engine block, houses the cylinders, pistons, and crankshaft. The components of
other engine systems bolt or attach to the engine block. The block is
manufactured with internal passageways for lubricants and coolant. Engine
blocks are made of cast iron or aluminum alloy and formed with a set of round
cylinders.
The upper part of the engine is
the cylinder head. Bolted to the top of the block, it seals the tops of the
cylinders. Pistons compress air and fuel against the cylinder head prior to
ignition. The top of the piston forms the floor of the combustion chamber. A
rod connects the bottom of the piston to the crankshaft. Lubricated bearings
enable both ends of the connecting rod to pivot, transferring the piston’s
vertical motion into the crankshaft’s rotational force, or torque. The pistons’
motion rotates the crankshaft at speeds ranging from about 600 to thousands of
revolutions per minute (rpm), depending on how much fuel is delivered to the
cylinders.
Fuel vapor enters and exhaust gases
leave the combustion chamber through openings in the cylinder head controlled
by valves. The typical engine valve is a metal shaft with a disk at one end
fitted to block the opening. The other end of the shaft is mechanically linked
to a camshaft, a round rod with odd-shaped lobes located inside the engine
block or in the cylinder head. Inlet valves open to allow fuel to enter the
combustion chambers. Outlet valves open to let exhaust gases out.
A gear wheel, belt, or chain links
the camshaft to the crankshaft. When the crankshaft forces the camshaft to
turn, lobes on the camshaft cause valves to open and close at precise moments
in the engine’s cycle. When fuel vapor ignites, the intake and outlet valves
close tightly to direct the force of the explosion downward on the piston.
B
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Engine Types
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The blocks in most internal-combustion
engines are in-line designs or V designs. In-line designs are arranged so that the
cylinders stand upright in a single line over the crankshaft. In a V design,
two rows of cylinders are set at an angle to form a V. At the bottom of the V
is the crankshaft. In-line configurations of six or eight cylinders require
long engine compartments found more often in trucks than in cars. The V design
allows the same number of cylinders to fit into a shorter, although wider,
space. Another engine design that fits into shorter, shallower spaces is a
horizontally opposed, or flat, arrangement in which the crankshaft lies between
two rows of cylinders.
Engines become more powerful, and use
more fuel, as the size and number of cylinders increase. Most modern vehicles
in the United States have 4-, 6-, or 8-cylinder engines, but car engines have
been designed with 1, 2, 3, 5, 12, and more cylinders.
Diesel engines, common in large trucks or
buses, are similar to gasoline internal-combustion engines, but they have a
different ignition system. Diesels compress air inside the cylinders with
greater force than a gasoline engine does, producing temperatures hot enough to
ignite the diesel fuel on contact. Some cars have rotary engines, also known as
Wankel engines, which have one or more elliptical chambers in which
triangular-shaped rotors, instead of pistons, rotate.
Electric motors have been used to power
automobiles since the late 1800s. Electric power supplied by batteries runs the
motor, which rotates a driveshaft, the shaft that transmits engine power to the
axles. Commercial electric car models for specialized purposes were available
in the 1980s. General Motors Corporation introduced a mass-production
all-electric car in the mid-1990s.
Automobiles that combine two or more types
of engines are called hybrids. A typical hybrid is an electric motor with batteries
that are recharged by a generator run by a small gas- or diesel-powered engine.
These hybrids are known as hybrid electric vehicles (HEVs). By relying more on
electricity and less on fuel combustion, HEVs have higher fuel efficiency and
emit fewer pollutants. Several automakers have experimented with hybrids.
In 1997 Toyota Motor Corporation
became the first to mass-produce a hybrid vehicle, the Prius. It became
available in Japan in 1997 and in North America in 2000. The first hybrid
available for sale in North America, the Honda Insight, was offered by Honda
Motor Co., Ltd., in 1999. Honda later introduced a hybrid version of the Honda
Civic. In August 2004 the Ford Motor Company became the first U.S. automaker to
release a hybrid vehicle when it began production of the Ford Escape Hybrid,
the first hybrid sport- utility vehicle (SUV). The Escape Hybrid was released
for the 2005 model year.
C
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Fuel Supply
|
The internal-combustion engine is powered by the
burning of a precise mixture of liquefied fuel and air in the cylinders’
combustion chambers. Fuel is stored in a tank until it is needed, then pumped
to a carburetor or, in newer cars, to a fuel-injection system.
The carburetor controls the mixture of gas
and air that travels to the engine. It mixes fuel with air at the head of a
pipe, called the intake manifold, leading to the cylinders. A vacuum created by
the downward strokes of pistons draws air through the carburetor and intake
manifold. Inside the carburetor, the airflow transforms drops of fuel into a
fine mist, or vapor. The intake manifold delivers the fuel vapor to the
cylinders, where it is ignited.
All new cars produced today are
equipped with fuel injection systems instead of carburetors. Fuel injectors
spray carefully calibrated bursts of fuel mist into cylinders either at or near
openings to the combustion chambers. Since the exact quantity of gas needed is
injected into the cylinders, fuel injection is more precise, easier to adjust,
and more consistent than a carburetor, delivering better efficiency, gas
mileage, engine responsiveness, and pollution control. Fuel-injection systems
vary widely, but most are operated or managed electronically.
High-performance automobiles are often fitted
with air-compressing equipment that increases an engine’s output. By increasing
the air and fuel flow to the engine, these features produce greater horsepower.
Superchargers are compressors powered by the crankshaft. Turbochargers are
turbine-powered compressors run by pressurized exhaust gas.
D
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Exhaust System
|
The exhaust system carries exhaust
gases from the engine’s combustion chamber to the atmosphere and reduces, or
muffles, engine noise. Exhaust gases leave the engine in a pipe, traveling
through a catalytic converter and a muffler before exiting through the
tailpipe.
Chemical reactions inside the catalytic
converter change most of the hazardous hydrocarbons and carbon monoxide
produced by the engine into water vapor and carbon dioxide.
The conventional muffler is an enclosed
metal tube packed with sound-deadening material. Most conventional mufflers are
round or oval-shaped with an inlet and outlet pipe at either end. Some contain
partitions to help reduce engine noise.
Car manufacturers are experimenting with an
electronic muffler, which uses sensors to monitor the sound waves of the
exhaust noise. The sound wave data are sent to a computer that controls
speakers near the tailpipe. The system generates sound waves 180 degrees out of
phase with the engine noise. The sound waves from the electronic muffler
collide with the exhaust sound waves and they cancel each other out, leaving
only low-level heat to emerge from the tailpipe.
E
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Cooling and Heating
System
|
Combustion inside an engine produces
temperatures high enough to melt cast iron. A cooling system conducts this heat
away from the engine’s cylinders and radiates it into the air.
In most automobiles, a liquid coolant
circulates through the engine. A pump sends the coolant from the engine to a
radiator, which transfers heat from the coolant to the air. In early engines,
the coolant was water. In most automobiles today, the coolant is a chemical
solution called antifreeze that has a higher boiling point and lower freezing
point than water, making it effective in temperature extremes. Some engines are
air cooled, that is, they are designed so a flow of air can reach metal fins
that conduct heat away from the cylinders.
A second, smaller radiator is fitted to
all modern cars. This unit uses engine heat to warm the interior of the
passenger compartment and supply heat to the windshield defroster.
III
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DRIVETRAIN
|
The rotational force of the engine’s crankshaft
turns other shafts and gears that eventually cause the drive wheels to rotate.
The various components that link the crankshaft to the drive wheels make up the
drivetrain. The major parts of the drivetrain include the transmission, one or
more driveshafts, differential gears, and axles.
A
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Transmission
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The transmission, also known as the gearbox,
transfers power from the engine to the driveshaft. As the engine’s crankshaft
rotates, combinations of transmission gears pass the energy along to a
driveshaft. The driveshaft causes axles to rotate and turn the wheels. By using
gears of different sizes, a transmission alters the rotational speed and torque
of the engine passed along to the driveshaft. Higher gears permit the car to
travel faster, while low gears provide more power for starting a car from a
standstill and for climbing hills.
The transmission usually is located just
behind the engine, although some automobiles were designed with a transmission
mounted on the rear axle. There are three basic transmission types: manual,
automatic, and continuously variable.
A manual transmission has a gearbox from
which the driver selects specific gears depending on road speed and engine
load. Gears are selected with a shift lever located on the floor next to the
driver or on the steering column. The driver presses on the clutch to disengage
the transmission from the engine to permit a change of gears. The clutch disk
attaches to the transmission’s input shaft. It presses against a circular plate
attached to the engine’s flywheel. When the driver presses down on the clutch
pedal to shift gears, a mechanical lever called a clutch fork and a device
called a throwout bearing separate the two disks. Releasing the clutch pedal
presses the two disks together, transferring torque from the engine to the
transmission.
An automatic transmission selects gears
itself according to road conditions and the amount of load on the engine.
Instead of a manual clutch, automatic transmissions use a hydraulic torque
converter to transfer engine power to the transmission.
Instead of making distinct changes from
one gear to the next, a continuously variable transmission uses belts and
pulleys to smoothly slide the gear ratio up or down. Continuously variable
transmissions appeared on machinery during the 19th century and on a few
small-engine automobiles as early as 1900. The transmission keeps the engine
running at its most efficient speed by more precisely matching the gear ratio
to the situation. Commercial applications have been limited to small engines.
B
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Front- and
Rear-Wheel Drive
|
Depending on the vehicle’s design,
engine power is transmitted by the transmission to the front wheels, the rear wheels,
or to all four wheels. The wheels receiving power are called drive wheels: They
propel the vehicle forward or backward. Most automobiles either are front-wheel
or rear-wheel drive. In some vehicles, four-wheel drive is an option the driver
selects for certain road conditions; others feature full-time, all-wheel drive.
The differential is a gear assembly in
an axle that enables each powered wheel to turn at different speeds when the
vehicle makes a turn. The driveshaft connects the transmission’s output shaft
to a differential gear in the axle. Universal joints at both ends of the
driveshaft allow it to rotate as the axles move up and down over the road
surface.
In rear-wheel drive, the driveshaft
runs under the car to a differential gear at the rear axle. In front-wheel
drive, the differential is on the front axle and the connections to the
transmission are much shorter. Four-wheel-drive vehicles have drive shafts and
differentials for both axles.
IV
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SUPPORT SYSTEMS
|
Automobiles would deliver jolting rides,
especially on unpaved roads, without a system of shock absorbers and other
devices to protect the auto body and passenger compartment from severe bumps
and bounces.
A
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Suspension System
|
The suspension system, part of the
undercarriage of an automobile, contains springs that move up and down to
absorb bumps and vibrations. In one type of suspension system, a long tube, or
strut, has a shock absorber built into its center section. Shock absorbers
control, or dampen, the sudden loading and unloading of suspension springs to
reduce wheel bounce and the shock transferred from the road wheels to the body.
One shock absorber is installed at each wheel. Modern shock absorbers have a
telescoping design and use oil, gas, and air, or a combination to absorb
energy.
Luxury sedans generally have a soft
suspension for comfortable riding. Sports cars and sport-utility vehicles have
firmer suspensions to improve cornering ability and control over rough terrain.
Older automobiles were equipped with
one-piece front axles attached to the frame with semielliptic leaf springs,
much like the arrangement on horse-drawn buggies. Front wheels on modern cars
roll independently of each other on half-shafts instead of on a common axle.
Each wheel has its own axle and suspension supports, so the shock of one wheel
hitting a bump is not transferred across a common axle to the other wheel or
the rest of the car. Many rear-axle suspensions for automobiles and heavier
vehicles use rigid axles with coil or leaf springs. However, advanced passenger
cars, luxury sedans, and sports cars feature independent rear-wheel suspension
systems.
Active suspensions are computer-controlled
adjustments of the downward force of each wheel as the vehicle corners or rides
over uneven terrain. Sensors, a pump, and hydraulic cylinders, all monitored
and controlled by computer, enable the vehicle to lean into corners and
compensate for the dips and dives that accompany emergency stops and rapid acceleration.
B
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Wheels and Tires
|
Wheels support the vehicle’s weight and
transfer torque to the tires from the drivetrain and braking systems.
Automobile wheels generally are made of steel or aluminum. Aluminum wheels are
lighter, more impact absorbent, and more expensive.
Pneumatic (air-filled) rubber tires, first
patented in 1845, fit on the outside rims of the wheels. Tires help smooth out
the ride and provide the automobile’s only contact with the road, so traction
and strength are primary requirements. Tire treads come in several varieties to
match driving conditions.
V
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CONTROL SYSTEMS
|
A driver controls the automobile’s
motion by keeping the wheels pointed in the desired direction, and by stopping
or slowing the speed at which the wheels rotate. These controls are made
possible by the steering and braking systems. In addition, the driver controls
the vehicle’s speed with the transmission and the gas pedal, which adjusts the
amount of fuel fed to the engine.
A
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Steering
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Automobiles are steered by turning the front
wheels, although a few automobile types have all-wheel steering. Most steering
systems link the front wheels together by means of a tie-rod. The tie-rod
insures that the turning of one wheel is matched by a corresponding turn in the
other.
When a driver turns the steering
wheel, the mechanical action rotates a steering shaft inside the steering
column. Depending on the steering mechanism, gears or other devices convert the
rotating motion of the steering wheel into a horizontal force that turns the
wheels.
Manual steering relies only on the force
exerted by the driver to turn the wheels. Conventional power steering uses
hydraulic pressure, operated by the pressure or movement of a liquid, to
augment that force, requiring less effort by the driver. Electric power
steering uses an electric motor instead of hydraulic pressure.
B
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Brakes
|
Brakes enable the driver to slow or
stop the moving vehicle. The first automobile brakes were much like those on
horse-drawn wagons. By pulling a lever, the driver pressed a block of wood,
leather, or metal, known as the shoe, against the wheel rims. With sufficient
pressure, friction between the wheel and the brake shoe caused the vehicle to
slow down or stop. Another method was to use a lever to clamp a strap or brake
shoes tightly around the driveshaft.
A brake system with shoes that
pressed against the inside of a drum fitted to the wheel, called drum brakes,
appeared in 1903. Since the drum and wheel rotate together, friction applied by
the shoes inside the drum slowed or stopped the wheel. Cotton and leather shoe
coverings, or linings, were replaced by asbestos after 1908, greatly extending
the life of the brake mechanism. Hydraulically assisted braking was introduced
in the 1920s. Disk brakes, in which friction pads clamp down on both sides of a
disk attached to the axle, were in use by the 1950s.
An antilock braking system (ABS) uses a
computer, sensors, and a hydraulic pump to stop the automobile’s forward motion
without locking the wheels and putting the vehicle into a skid. Introduced in
the 1980s, ABS helps the driver maintain better control over the car during
emergency stops and while braking on slippery surfaces.
Automobiles are also equipped with a
hand-operated brake used for emergencies and to securely park the car,
especially on uneven terrain. Pulling on a lever or pushing down on a foot
pedal sets the brake.
VI
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ELECTRICAL SYSTEM
|
The automobile depends on electricity for
fuel ignition, headlights, turn signals, horn, radio, windshield wipers, and
other accessories. A battery and an alternator supply electricity. The battery
stores electricity for starting the car. The alternator generates electric
current while the engine is running, recharging the battery and powering the
rest of the car’s electrical needs.
Early automotive electrical systems ran on 6
volts, but 12 volts became standard after World War II (1939-1945) to operate
the growing number of electrical accessories. Eventually, 24- or 48-volt
systems may become the standard as more computers and electronics are built
into automobiles.
A
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Ignition System
|
The ignition system supplies
high-voltage current to spark plugs to ignite fuel vapor in the cylinders.
There are many variations, but all gasoline-engine ignition systems draw
electric current from the battery, significantly increase the current’s
voltage, then deliver it to spark plugs that project into the combustion
chambers. An electric arc between two electrodes at the bottom of the spark
plug ignites the fuel vapor.
In older vehicles, a distributor,
which is an electrical switching device, routes high-voltage current to the
spark plugs. The distributor’s housing contains a switch called the breaker
points. A rotating shaft in the distributor causes the switch to open and
close, interrupting the supply of low-voltage current to a transformer called a
coil. The coil uses electromagnetic induction (see Electricity: Electromagnetism)
to convert interruptions of the 12-volt current into surges of 20,000 volts or
more. This high-voltage current passes back to the distributor, which
mechanically routes it through wires to spark plugs, producing a spark that
ignites the gas vapor in the cylinders. A condenser absorbs excess current and
protects the breaker points from damage by the high-voltage surge. The
distributor and other devices control the timing of the spark-plug discharges.
In modern ignition systems, the
distributor, coil, points, and condenser have been replaced by solid-state
electronics controlled by a computer. A computer controls the ignition system
and adjusts it to provide maximum efficiency in a variety of driving
conditions.
VII
|
SAFETY FEATURES
|
Manufacturers continue to build lighter vehicles
with improved structural rigidity and ability to protect the driver and
passengers during collisions.
Bumpers evolved as rails or bars to
protect the front and rear of the car’s body from damage in minor collisions.
Over the years, bumpers became stylish and, in some cases, not strong enough to
survive minor collisions without expensive repairs. Eventually, government
regulations required bumpers designed to withstand low-speed collisions with
less damage. Some bumpers can withstand 4-km/h (2.5-mph) collisions with no
damage, while others can withstand 8-km/h (5-mph) collisions with no damage.
Modern vehicles feature crumple zones,
portions of the automobile designed to absorb forces that otherwise would be
transmitted to the passenger compartment. Passenger compartments on many
vehicles also have reinforced roll bar structures in the roof, in case the
vehicle overturns, and protective beams in the doors to help protect passengers
from side impacts.
Seat belt and upper-body restraints
that relax to permit comfort but tighten automatically during an impact are now
common. Some car models are equipped with shoulder-restraint belts that slide
into position automatically when the car’s doors close.
An air bag is a high-speed
inflation device hidden in the hub of the steering wheel or in the dash on the
passenger’s side. Some automobiles have side-impact air bags, located in doors
or seats. At impact, the bag inflates almost instantaneously. The inflated bag
creates a cushion between the occupant and the vehicle’s interior. Air bags
first appeared in the mid-1970s, available as an optional accessory. Today they
are installed on all new passenger cars sold in the United States.
Air bags inflate with great force,
which occasionally endangers a child or infant passenger. Some newer automobile
models are equipped with switches to disable the passenger-side air bags when a
child or infant is traveling in the passenger seat. Automakers continue to
research ways to make air-bag systems less dangerous for frail and small
passengers, yet effective in collisions.
VIII
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HISTORY
|
The history of the automobile
actually began about 4,000 years ago when the first wheel was used for
transportation in India. In the early 15th century the Portuguese arrived in
China and the interaction of the two cultures led to a variety of new
technologies, including the creation of a wheel that turned under its own
power. By the 1600s small steam-powered engine models had been developed, but
it was another century before a full-sized engine-powered vehicle was created.
In 1769 French Army officer
Captain Nicolas-Joseph Cugnot built what has been called the first automobile.
Cugnot’s three-wheeled, steam-powered vehicle carried four persons. Designed to
move artillery pieces, it had a top speed of a little more than 3.2 km/h (2
mph) and had to stop every 20 minutes to build up a fresh head of steam.
As early as 1801 successful but
very heavy steam automobiles were introduced in England. Laws barred them from
public roads and forced their owners to run them like trains on private tracks.
In 1802 a steam-powered coach designed by British engineer Richard Trevithick
journeyed more than 160 km (100 mi) from Cornwall to London. Steam power caught
the attention of other vehicle builders. In 1804 American inventor Oliver Evans
built a steam-powered vehicle in Chicago, Illinois. French engineer Onésiphore
Pecqueur built one in 1828.
British inventor Walter Handcock built a
series of steam carriages in the mid-1830s that were used for the first omnibus
service in London. By the mid-1800s England had an extensive network of steam
coach lines. Horse-drawn stagecoach companies and the new railroad companies
pressured the British Parliament to approve heavy tolls on steam-powered road
vehicles. The tolls quickly drove the steam coach operators out of business.
During the early 20th century steam
cars were popular in the United States. Most famous was the Stanley Steamer,
built by American twin brothers Freelan and Francis Stanley. A Stanley Steamer
established a world land speed record in 1906 of 205.44 km/h (121.573 mph).
Manufacturers produced about 125 models of steam-powered automobiles, including
the Stanley, until 1932.
A
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Internal-Combustion
Engine
|
Development of lighter steam cars during the
19th century coincided with major developments in engines that ran on gasoline
or other fuels. Because the newer engines burned fuel in cylinders inside the
engine, they were called internal-combustion engines.
In 1860 French inventor
Jean-Joseph-Étienne Lenoir patented a one-cylinder engine that used kerosene
for fuel. Two years later, a vehicle powered by Lenoir’s engine reached a top
speed of about 6.4 km/h (about 4 mph). In 1864 Austrian inventor Siegfried
Marcus built and drove a carriage propelled by a two-cylinder gasoline engine.
American George Brayton patented an internal-combustion engine that was
displayed at the 1876 Centennial Exhibition in Philadelphia, Pennsylvania.
In 1876 German engineer Nikolaus August
Otto built a four-stroke gas engine, the most direct ancestor to today’s
automobile engines. In a four-stroke engine the pistons move down to draw fuel
vapor into the cylinder during stroke one; in stroke two, the pistons move up
to compress the vapor; in stroke three the vapor explodes and the hot gases
push the pistons down the cylinders; and in stroke four the pistons move up to
push exhaust gases out of the cylinders. Engines with two or more cylinders are
designed so combustion occurs in one cylinder after the other instead of in all
at once. Two-stroke engines accomplish the same steps, but less efficiently and
with more exhaust emissions.
Automobile manufacturing began in earnest in
Europe by the late 1880s. German engineer Gottlieb Daimler and German inventor
Wilhelm Maybach mounted a gasoline-powered engine onto a bicycle, creating a
motorcycle, in 1885. In 1887 they manufactured their first car, which included
a steering tiller and a four-speed gearbox. Another German engineer, Karl Benz,
produced his first gasoline car in 1886. In 1890 Daimler and Maybach started a
successful car manufacturing company, The Daimler Motor Company, which
eventually merged with Benz’s manufacturing firm in 1926 to create
Daimler-Benz. The joint company makes cars today under the Mercedes-Benz
nameplate (see DaimlerChrysler AG).
In France, a company called
Panhard-Levassor began making cars in 1894 using Daimler’s patents. Instead of
installing the engine under the seats, as other car designers had done, the
company introduced the design of a front-mounted engine under the hood.
Panhard-Levassor also introduced a clutch and gears, and separate construction
of the chassis, or underlying structure of the car, and the car body. The
company’s first model was a gasoline-powered buggy steered by a tiller.
French bicycle manufacturer Armand Peugeot
saw the Panhard-Levassor car and designed an automobile using a similar Daimler
engine. In 1891 this first Peugeot automobile paced a 1,046-km (650-mi)
professional bicycle race between Paris and Brest. Other French automobile
manufacturers opened shop in the late 1800s, including Renault. In Italy, Fiat
(Fabbrica Italiana Automobili di Torino) began building cars in 1899.
American automobile builders were not far
behind. Brothers Charles Edgar Duryea and James Frank Duryea built several
gas-powered vehicles between 1893 and 1895. The first Duryea, a one-cylinder,
four-horsepower model, looked much like a Panhard-Levassor model. In 1893
American industrialist Henry Ford built an internal-combustion engine from
plans he saw in a magazine. In 1896 he used an engine to power a vehicle
mounted on bicycle wheels and steered by a tiller.
B
|
Early Electric Cars
|
For a few decades in the
1800s, electric engines enjoyed great popularity because they were quiet and
ran at slow speeds that were less likely to scare horses and people. By 1899 an
electric car designed and driven by Belgian inventor Camille Jenatzy set a
record of 105.8810 km/h (65.79 mph).
Early electric cars featured a large
bank of storage batteries under the hood. Heavy cables connected the batteries
to a motor between the front and rear axles. Most electric cars had top speeds
of 48 km/h (30 mph), but could go only 80 km (50 mi) before their batteries
needed recharging. Electric automobiles were manufactured in quantity in the
United States until 1930.
IX
|
AUTOMOBILES IN THE
20TH CENTURY
|
For many years after the
introduction of automobiles, three kinds of power sources were in common use:
steam engines, gasoline engines, and electric motors. In 1900 more than 2,300
automobiles were registered in New York City; Boston, Massachusetts; and
Chicago, Illinois. Of these, 1,170 were steam cars, 800 were electric cars, and
only 400 were gasoline cars. Gasoline-powered engines eventually became the
nearly universal choice for automobiles because they allowed longer trips and
faster speeds than engines powered by steam or electricity.
But development of gasoline cars in the
early 1900s was hindered in the United States by legal battles over a patent
obtained by New York lawyer George B. Selden. Selden saw a gasoline engine at
the Philadelphia Centennial Exposition in 1876. He then designed a similar one
and obtained a broad patent that for many years was interpreted to apply to all
gasoline engines for automobiles. Although Selden did not manufacture engines
or automobiles, he collected royalties from those who did.
Henry Ford believed Selden’s patent was
invalid. Selden sued when Ford refused to pay royalties for Ford-manufactured
engines. After eight years of court battles, the courts ruled in 1911 that
Selden’s patent applied only to two-stroke engines. Ford and most other
manufacturers were using four-stroke engines, so Selden could not charge them
royalties.
Improvements in the operating and
riding qualities of gasoline automobiles developed quickly after 1900. The 1902
Locomobile was the first American car with a four-cylinder, water-cooled,
front-mounted gasoline engine, very similar in design to most cars today.
Built-in baggage compartments appeared in 1906, along with weather resistant tops
and side curtains. An electric self-starter was introduced in 1911 to replace
the hand crank used to start the engine turning. Electric headlights were
introduced at about the same time.
Most automobiles at the turn of the
20th century appeared more or less like horseless carriages. In 1906
gasoline-powered cars were produced that had a style all their own. In these
new models, a hood covered the front-mounted engine. Two kerosene or acetylene
lamps mounted to the front served as headlights. Cars had fenders that covered
the wheels and step-up platforms called running boards, which helped passengers
get in and out of the vehicle. The passenger compartment was behind the engine.
Although drivers of horse-drawn vehicles usually sat on the right, automotive steering
wheels were on the left in the United States.
In 1903 Henry Ford incorporated
the Ford Motor Company, which introduced its first automobile, the Model A, in
that same year. It closely resembled the 1903 Cadillac, which was hardly
surprising since Ford had designed cars the previous year for the Cadillac
Motor Car Company. Ford’s company rolled out new car models each year, and each
model was named with a letter of the alphabet. By 1907, when models R and S
appeared, Ford’s share of the domestic automobile market had soared to 35
percent.
Ford’s famous Model T debuted in 1908
but was called a 1909 Ford. Ford built 17,771 Model T’s and offered nine body
styles. Popularly known as the Tin Lizzy, the Model T became one of the
biggest-selling automobiles of all time. Ford sold more than 15 million before
stopping production of the model in 1927. The innovative assembly-line method
used by the company to build its cars was widely adopted in the automobile
industry.
By 1920 more than 8 million
Americans owned cars. Major reasons for the surge in automobile ownership were
Ford’s Model T, the assembly-line method of building it, and the affordability
of cars for the ordinary wage earner.
Improvements in engine-powered cars during
the 1920s contributed to their popularity: synchromesh transmissions for easier
gear shifting; four-wheel hydraulic brake systems; improved carburetors;
shatterproof glass; balloon tires; heaters; and mechanically operated
windshield wipers.
From 1930 to 1937, automobile
engines and bodies became large and luxurious. Many 12- and 16-cylinder cars
were built. Independent front suspension, which made the big cars more
comfortable, appeared in 1933. Also introduced during the 1930s were stronger,
more reliable braking systems, and higher-compression engines, which developed
more horsepower. Mercedes introduced the world’s first diesel car in 1936.
Automobiles on both sides of the Atlantic were styled with gracious
proportions, long hoods, and pontoon-shaped fenders. Creative artistry merged
with industrial design to produce appealing, aerodynamic automobiles.
Some of the first vehicles to
fully incorporate the fender into the bodywork came along just after World War
II, but the majority of designs still had separate fenders with pontoon shapes
holding headlight assemblies. Three companies, Ford, Nash, and Hudson Motor Car
Company, offered postwar designs that merged fenders into the bodywork. The
1949 Ford was a landmark in this respect, and its new styling was so well
accepted the car continued in production virtually unchanged for three years,
selling more than 3 million. During the 1940s, sealed-beam headlights, tubeless
tires, and the automatic transmission were introduced.
Two schools of styling emerged in the
1950s, one on each side of the Atlantic. The Europeans continued to produce
small, light cars weighing less than 1,300 kg (2,800 lb). European sports cars
of that era featured hand-fashioned aluminum bodies over a steel chassis and
framework.
In America, automobile designers borrowed
features for their cars that were normally found on aircraft and ships,
including tailfins and portholes. Automobiles were produced that had more
space, more power, and smoother riding capability. Introduction of power
steering and power brakes made bigger cars easier to handle. The Buick Motor
Car Company, Olds Motor Vehicle Company (Oldsmobile), Cadillac Automobile
Company, and Ford all built enormous cars, some weighing as much as 2,495 kg
(5,500 lb).
The first import by German
manufacturer Volkswagen AG, advertised as the Beetle, arrived in the United
States in 1949. Only two were sold that year, but American consumers soon began
buying the Beetle and other small imports by the thousands. That prompted a
downsizing of some American-made vehicles. The first American car called a
compact was the Nash Rambler. Introduced in 1950, it did not attract buyers on
a large scale until 1958. More compacts, smaller in overall size than a
standard car but with virtually the same interior body dimensions, emerged from
the factories of many major manufacturers. The first Japanese imports, 16
compact trucks, arrived in the United States in 1956.
In the 1950s new automotive
features were introduced, including air conditioning and electrically operated
car windows and seat adjusters. Manufacturers changed from the 6-volt to the
12-volt ignition system, which gave better engine performance and more reliable
operation of the growing number of electrical accessories.
By 1960 sales of foreign and
domestic compacts accounted for about one-third of all passenger cars sold in
the United States. American cars were built smaller, but with increased engine
size and horsepower. Heating and ventilating systems became standard equipment
on even the least expensive models. Automatic transmissions, power brakes, and
power steering became widespread. Styling sometimes prevailed over
practicality—some cars were built in which the engines had to be lifted to
allow simple service operations, like changing the spark plugs. Back seats were
designed with no legroom.
In the 1970s American manufacturers
continued to offer smaller, lighter models in addition to the bigger sedans
that led their product lines, but Japanese and European compacts continued to
sell well. Catalytic converters were introduced to help reduce exhaust
emissions.
During this period, the auto industry
was hurt by the energy crisis, created when the Organization of Petroleum
Exporting Countries (OPEC), a cartel of oil-producing countries, cut back on
sales to other countries. The price of crude oil skyrocketed, driving up the
price of gasoline. Large cars were getting as little as 8 miles per gallon
(mpg), while imported compacts were getting as much as 35 mpg. More buyers
chose the smaller, more fuel-efficient imports.
Digital speedometers and electronic prompts
to service parts of the vehicle appeared in the 1980s. Japanese manufacturers
opened plants in the United States. At the same time, sporty cars and family
minivans surged in popularity.
Advances in automobile technology in the
1980s included better engine control and the use of innovative types of fuel.
In 1981 Bayerische Motoren Werke AG (BMW) introduced an on-board computer to
monitor engine performance. A solar-powered vehicle, SunRaycer, traveled 3,000
km (1,864 mi) in Australia in six days.
X
|
NEW TECHNOLOGIES
|
A
|
Antipollution
Strategies
|
Pollution-control laws adopted at the beginning
of the 1990s in some of the United States and in Europe called for automobiles
that produced better gas mileage with lower emissions. The California Air
Resources Board required companies with the largest market shares to begin
selling vehicles that were pollution free—in other words, electric. In 1996
General Motors became the first to begin selling an all-electric car, the EV1,
to California buyers. The all-electric cars introduced so far have been limited
by low range, long recharges, and weak consumer interest.
Engines that run on hydrogen have
been tested. Hydrogen combustion produces only a trace of harmful emissions, no
carbon dioxide, and a water-vapor by-product. However, technical problems
related to the gas’s density and flammability remain to be solved.
Diesel engines burn fuel more
efficiently, and produce fewer pollutants, but they are noisy. Popular in
trucks and heavy vehicles, diesel engines are only a small portion of the
automobile market. A redesigned, quieter diesel engine introduced by Volkswagen
in 1996 may pave the way for more diesels, and less pollution, in passenger
cars.
B
|
Hybrid-Electric
Vehicles (HEVs)
|
While some developers searched for
additional alternatives, others investigated ways to combine electricity with liquid
fuels to produce low-emissions power systems. The hybrid-electric vehicle (HEV)
uses both an electric motor or motors and a gasoline or diesel engine that
charges the batteries in order to extend the distance that the vehicle can
travel without having to recharge the batteries. An HEV at a stoplight
typically sits silent, burning no fuel and making no pollution, if the
batteries are sufficiently charged. If driven slowly, as in heavy traffic, the
vehicle might move only on electric power. Only when more power is demanded for
acceleration or to move a heavy load, does the gasoline or diesel engine come
into play.
Two automobiles with such hybrid
engines, the Toyota Prius and the Honda Insight, became available in the late
1990s. The Prius hit automobile showrooms in Japan in 1997, selling 30,000
models in its first two years of production. The Prius became available for
sale in North America in 2000. The Honda Insight debuted in North America in
late 1999. Both vehicles promised to double the fuel efficiency of conventional
gasoline-powered cars while significantly reducing toxic emissions. The Ford
Motor Company introduced the first U.S.-made hybrid when it began production
for the Ford Escape Hybrid in August 2004. The 2005 model year Escape was also the
first hybrid in the sport-utility vehicle (SUV) category. Electric Car.
C
|
Computers and
Navigation Devices
|
Computer control of automobile systems
increased dramatically during the 1990s. The central processing unit (CPU) in modern
engines manages overall engine performance. Microprocessors regulating other
systems share data with the CPU. Computers manage fuel and air mixture ratios,
ignition timing, and exhaust-emission levels. They adjust the antilock braking
and traction control systems. In many models, computers also control the air
conditioning and heating, the sound system, and the information displayed in
the vehicle’s dashboard.
Expanded use of computer technology,
development of stronger and lighter materials, and research on pollution
control will produce better, “smarter” automobiles. In the 1980s the notion
that a car would “talk” to its driver was science fiction; by the 1990s it had
become reality.
Onboard navigation was one of the new
automotive technologies in the 1990s. By using the satellite-aided global
positioning system (GPS), a computer in the automobile can pinpoint the
vehicle’s location within a few meters. The onboard navigation system uses an
electronic compass, digitized maps, and a display screen showing where the
vehicle is relative to the destination the driver wants to reach. After being
told the destination, the computer locates it and directs the driver to it,
offering alternative routes if needed.
Some cars now come equipped with
GPS locator beacons, enabling a GPS system operator to locate the vehicle, map
its location, and if necessary, direct repair or emergency workers to the
scene.
Cars equipped with computers and
cellular telephones can link to the Internet to obtain constantly updated traffic
reports, weather information, route directions, and other data. Future built-in
computer systems may be used to automatically obtain business information over
the Internet and manage personal affairs while the vehicle’s owner is driving.
D
|
Other Improvements
|
During the 1980s and 1990s,
manufacturers trimmed 450 kg (1,000 lb) from the weight of the typical car by
making cars smaller. Less weight, coupled with more efficient engines, doubled
the gas mileage obtained by the average new car between 1974 and 1995. Further
reductions in vehicle size are not practical, so the emphasis has shifted to
using lighter materials, such as plastics, aluminum alloys, and carbon
composites, in the engine and the rest of the vehicle.
Looking ahead, engineers are devising ways
to reduce driver errors and poor driving habits. Systems already exist in some
locales to prevent intoxicated drivers from starting their vehicles. The
technology may be expanded to new vehicles. Anticollision systems with sensors
and warning signals are being developed. In some, the car’s brakes
automatically slow the vehicle if it is following another vehicle too closely.
New infrared sensors or radar systems may warn drivers when another vehicle is
in their “blind spot.”
Catalytic converters work only when they are
warm, so most of the pollution they emit occurs in the first few minutes of
operation. Engineers are working on ways to keep the converters warm for longer
periods between drives, or heat the converters more rapidly.
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