Industry's Vast Influence

By the early 1990s more than 50 million automobiles were being manufactured worldwide annually. Leading manufacturing areas were Japan, the United States, and Western Europe. There was also significant production in Eastern Europe and Latin America. The automotive industry is so vast that it influences, directly or indirectly, most of the people on Earth. In industrial nations the level of automobile production has become a barometer of the economy and is closely watched by political leaders and business analysts. Changes in auto production directly affect the large steel, aluminum, petroleum, and rubber industries and their suppliers and employees. A long strike in the automobile industry or a sharp drop in sales can result in a general business decline (see Automobile Industry).

Uses

Although the size of the automobile industry is impressive, it is the use of automotive vehicles that has had the greatest effect on people's lives. Foods arrive fresh at processing plants or at local markets because of the automotive vehicle. Many other products in common use are also distributed quickly and inexpensively by motor trucks.

Many services other than transportation depend on the automobile. Public utilities are built and maintained by crews using automotive equipment. Ambulance, fire, and police services depend on the automobile. The construction industry uses a variety of special vehicles to prepare building sites and to haul materials and to put them in place. Farmers use automobiles, trucks, tractors, and motorized harvest and planting equipment.

The armies of the world rely on motor vehicles to move soldiers and supplies and to assault the enemy. Modern military strategy involves highly mobile armies supported by tanks, armored personnel carriers, and supply trucks.

Way of Life

Before the automobile was developed, people lived near their places of work. Many now commute between suburban residential areas and industrial or office areas in the city. Shopping centers, banks, restaurants, and even churches have been arranged to serve people in automobiles. Because so much vacation and other pleasure touring is done in automobiles, motels and parks have accommodations for large numbers of passenger cars, vehicles towing trailers, and light trucks (often called recreational vehicles, or RV's) that contain kitchen facilities and beds. An entire industry supports automotive hobbyists who collect and restore antique or classic cars, collect and drive sports cars, or modify their vehicles in many ways. Both children and adults make miniature car models.

Types and Styles

A closed automobile that seats from four to six people is called a sedan. It may be a four-door or a two-door model. Two-door sedans sometimes have a rear lift-up door and a backseat that can be turned down to produce a flat storage, or hauling, space. This sedan is called a hatchback.

A coupe, or coupé, originally was a two-door automobile with a single wide seat. The modern coupe, or club coupe, usually has a backseat, enclosed in a somewhat smaller area than the rear seat of a sedan. A convertible is a car with a soft top that may be folded back and down. A hardtop is styled to resemble a convertible in the omission of a center post between front and back windows but has a permanent rigid top. A station wagon usually accommodates more people and cargo than a standard passenger car, and the backseats can be removed or turned down to provide still more cargo space. There is also a rear-end door, often a lift-up type as in a hatchback.

The long, heavy, and extravagantly designed full-size cars of the 1950s and 1960s were largely supplanted in the 1970s and 1980s by smaller, lighter, compact and subcompact cars. This happened as gasoline prices rose, making fuel-efficient cars economically desirable, and as manufacturers complied in some countries with government gas consumption mandates. The shrinking automobile was most evident in the United States, where fuel prices had been low, and large, powerful cars had long been popular. Some United States manufacturers produced models that lost as much as 1,000 pounds (450 kilograms) of weight and a foot (30 centimeters) in length from one year to the next.

A sports car is one of a variety of automobiles ordinarily used for pleasure driving. The typical sports car has low, sleek lines, high top speeds, and rapid acceleration. A limousine is a long luxury car usually driven by a chauffeur.

Two hybrid-type automotive vehicles are the van, a boxy truck that may be decorated elaborately and used to carry passengers, and the recreational vehicle (RV), a long van that is often equipped with beds and a kitchen.

Interior

The passenger car interior is designed to keep the driver safely in control. Gauges and switches, grouped and recessed into the dashboard, are surrounded with stiff padding.

Contemporary electronic instrumentation is reliable and informative. Much of the instrumentation has been computerized. Lights and alarms may indicate low fuel, outside light malfunction, improperly closed doors, or unfastened seat belts.

Some automobiles have microcomputer instrumentation, including a bar chart fuel gauge, digital speedometer, and message center. The center can provide information about numerous mechanical conditions and can tell how many miles remain to a particular destination. Some vehicles use a computer chip to determine fuel consumption on both an overall average and an instantaneous basis.

Many cars have bucket seats in front. These are individual rounded seats, set close to the floor. Other automobile interior features include heaters and air conditioners, power-operated windows and seats, and radios and audio tape players.

Bumpers, Lights, and Accessories

Bumpers that absorb impact from minor collisions at low speeds, therefore protecting a car's body from damage, are standard on many automobiles. These bumpers are of two types: the mechanical telescoping model and the one made of material that yields on impact and springs back into shape.

An automobile's lighting system includes dim and bright headlights, parking lights, turn signals, tail lights, backup lights, stoplights, ceiling lights, and dashboard lights. Some cars have map lights, floor lights, and cornering lights, or sidelights, that switch on automatically when the car is turned.

Other accessories, which can be both standard and optional, include safety glass, defrosters, rearview and side view mirrors, windshield wipers and washers, clocks, and cigarette lighters. Safety belts are now standard equipment.

Classification

There are many types of automotive power plants. They may be classified in a number of ways—by the number and arrangement of pistons and cylinders, by the means of ignition, or by the type of cooling system. When vertical pistons are arranged in a single row, the engine is called in-line. When the cylinders are in two rows, sloping inward at the bottom, the engine is called a V-type. Designations such as V-8 or V-6 indicate the number of cylinders.

Some compact cars have flat, or opposing, cylinder arrangements in their power plants. The pistons lie horizontally in pairs and oppose each other, with a crankshaft between them. Gas turbine engines have been used in trucks and military vehicles. The turbine is rotated by the force of expanding gas. Some of the heat given off by the gas is in turn reused, or regenerated, by the engine.

The free-piston engine, an experimental type, operates by internal combustion, though the pistons do not produce torque, or rotating power. Riding free in a chamber, they are bounced back by trapped air to compress the air-fuel mixture. The burning and expanding gas is ignited and then expelled into a turbine to provide torque.

There is an engine without pistons or a turbine. This is the rotating engine. Sometimes it is called a rotary engine, though this term is also used to describe a piston engine with cylinders that rotate around a crankshaft. The Wankel rotating engine, which was developed by Felix Wankel of West Germany, has three moving parts.

A three-sided rotor in the engine is mounted eccentrically (off-center) on a drive shaft. Compartments are formed between each side of the rotor and the chamber walls. As the rotor turns, the sealed compartments alternately become larger and smaller in rapid succession, serving much like the varying chambers of a piston engine—drawing in fuel and air, compressing the mixture and igniting it, and expelling the burned gas. The expansion of the gas forces the rotor to spin in a circular motion and turn the shaft. The Wankel engine is used by one automobile manufacturer. It is much smaller and lighter than the conventional piston engine.

Fuel System

The fuel system of an automobile includes the fuel tank, fuel pump, one or more carburetors, and connecting fuel lines. An air cleaner is mounted on top of the carburetor to remove dust and dirt from incoming air that is to be mixed with fuel and used for combustion. The throttle valve is controlled by the accelerator pedal. A choke valve is used to shut off some of the air during the starting of the car. This produces an air-fuel mixture rich in fuel. The choke valve is controlled either manually from the car's dashboard or, more often, automatically.

Most carburetors have at least two fuel passages, called jets, from the float chamber to the mixing chamber. The first jet provides fuel for idling and low speeds; the second provides fuel for higher speeds. Passages called intake manifolds transmit the air-fuel mixture to the cylinders. Some engines, and all diesel engines, use fuel injection, a system whereby a carefully measured amount of fuel is forced into the combustion chamber at high pressure.

Valves and Camshaft

The air-fuel mixture enters a combustion chamber, or cylinder, of the engine whenever the corresponding valve is opened. The opening and closing of the valves are accomplished by the camshaft, which turns with the engine. In most engines projections on the camshaft raise a pushrod that is connected with a valve. In the overhead valve engine the pushrod moves the rocker arm, which in turn opens the intake valve. As the cam continues to turn, the pushrod moves down again, and the intake valve closes. The exhaust valve operates on the same principle. The camshaft is geared to the crankshaft, or central power shaft. Gearing of the two shafts so that the valves will open and close at the correct moment is called timing the valves.

Electrical System

Instantaneous ignition of the explosive air-fuel mixture in each cylinder of the engine requires a strong, hot electric spark. This spark is caused by a momentary surge of high voltage, which may reach 20,000 to 25,000 volts. The voltage is supplied by a small induction coil. The surge occurs when the flow of electricity in the primary winding of the induction coil is interrupted by the opening of a breaker arm. A rotor permits the high-voltage surge to pass to each spark plug and trigger combustion in the cylinders in precisely timed sequence.

In the 1970s transistorized circuitry replaced the points and condenser in automotive ignitions. The resulting electronic ignition, combined with spark plugs of extended life, improved automotive reliability and lengthened the normal interval between tune-ups from 4,000 to 12,000 miles (6,000 to 18,000 kilometers).

The ignition system, as well as lights and other electrical devices in the car, is supplied with current from a 6- or 12-volt storage battery (see Battery and Fuel Cell). The battery is charged during operation of the vehicle by a direct-current (DC) generator powered by the engine. A variation of the generator, called an alternator, or alternating-current (AC) generator, has been developed. The AC is changed, or rectified, to DC by means of a diode, or type of electron tube. Unlike the ordinary car generator, the alternator continues to charge the battery while the engine is at its lowest, or idling, speed. The storage battery also powers the starter. This is an electric motor that cranks, or turns, the engine until the spark plugs ignite the air-fuel mixture.

Four-Stroke Cycle Engine

Most automotive engines are four-stroke cycle engines. Each up and each down movement of the piston is a stroke. Four strokes are needed to complete one cycle. The strokes of the cycle are the intake, compression, power, and exhaust strokes.

An important characteristic of engine operation is the compression ratio. This is the relation of the size of the piston chamber when the piston is at its lowest position to its size when the piston is in the top position. If the total volume of a cylinder is, for example, 35 cubic inches (574 cubic centimeters) and the piston at the top of the stroke leaves a space of 5 cubic inches (82 cubic centimeters), the air-fuel mixture has been compacted to one seventh of its original volume, and the compression ratio is seven to one.

The ability of gasoline to operate at a specified compression ratio is measured in octane ratings (see Gasoline). Gasoline rated too low for a specified engine may ignite prematurely and produce a pinging sound, called knock.

Another cause of engine knock is accumulation of soot (carbon) as a hard deposit inside the cylinder. Pieces of carbon become red-hot and act like a spark to cause premature ignition. Occasionally running the engine at high speed or driving the car at maximum highway speeds does much to avoid or clean out this accumulation of carbon. Missing is a term used to describe failure of the air-fuel mixture to ignite. It may be caused by a cold engine. The compression ratio is a good indication of engine performance. The greater the ratio of an engine, the more power it delivers per unit of fuel. An automobile's horsepower rating is also usually given. One horsepower is the force needed to move 33,000 pounds (15,000 kilograms) one foot (30 centimeters) in one minute.

The cylinders of the engine are molded into a cylinder block, a heavy block of metal. The cylinder head is a separate casting that is bolted to the block. Most cylinder blocks and heads are made of cast iron, though some are made of aluminum. The pistons turn the crankshaft by means of connecting rods. Attached to the crankshaft is a heavy flywheel, which helps keep engine speed steady.

Exhaust System

The exhaust system includes the exhaust manifold, muffler, exhaust pipe, and tail pipe. Through the manifold the burned gases are carried off to the muffler, which reduces the pressure of the gases and discharges them quietly through the tail pipe.

Since about 1975 most automotive exhaust systems have been equipped with catalytic converters—flat and rectangular devices placed along the tail pipe in much the same fashion as a muffler. They contain pellets that are coated with tiny amounts of platinum and palladium. These metals act as catalysts in a chemical reaction within the converter that transforms the exhaust pollutants into carbon dioxide and water.

Until the mid-1970s most automobiles used gasoline to which compounds of lead had been added. These substances improve engine performance but enter the atmosphere in automotive exhausts, causing pollution. Most cars now use lead-free gasoline. Leaded fuel contaminates catalytic converters, reducing their effectiveness.

Afterburners have also been devloped to reduce pollution. They burn compounds in exhaust gases so they do not reach the atmosphere. The blow-by, a variation, recirculates smog-producing gases into the combustion chamber to be burned.

Cooling System

Water from the radiator is circulated through the water jacket, or passages around the cylinders, to cool the engine. A centrifugal water pump generally is used in automobiles. The water, entering at the center, is caught by the vanes of the pump and is thrown to the outside by centrifugal force. The pressure imparted to the water carries it to the pipe leading to the water jacket. A thermostatic valve prevents water from circulating through the radiator until the temperature has reached a degree suitable for efficient engine operation. Some engines depend on a flow of air over the engine and have no liquid coolant.

Lubrication System

The presence of an oil film between two metal surfaces working together reduces friction and prevents parts from overheating and wearing. Several different systems are used to keep the engine parts of a car lubricated. The one most in use is a pressure system called force feed. A pump supplies oil through lines to wherever it is needed.

A simpler arrangement is the splash system. Troughs of oil are located inside the crankcase under the connecting rods. The rods are fitted with dippers at the lower ends. As the engine runs, these throw and splash oil inside the engine.

Few cars now depend on the splash system alone. Oil is usually pumped to the main bearings of the crankshaft, the connecting rod bearings, and the camshaft bearings. In most systems it reaches the main bearings through passages in the crankshaft.

Screens are provided at the intake opening of the oil pump to prevent the entrance of dirt. To permit a change of the engine oil supply, a drain plug is provided. Some parts of the car that formerly needed lubrication are now greased permanently. The lubricant is sealed in before the car leaves the factory.

Clutch

It is not practical to connect the wheels of an automobile directly to the engine. A device is needed to uncouple the wheels from the running engine so that the driver can warm the engine and keep it running while the vehicle is not moving. The engine must also be separated from the gearbox when the driver is shifting gears. Most automobiles provide for this uncoupling either with a friction (disk) clutch or with a fluid coupling.

Transmission

The transmission is a device installed at some point between the engine and the driving wheels of a vehicle to change speed and power. Power from the engine is provided in the form of torque, or twisting force. The amount of this force varies a great deal, depending on the individual characteristics of the engine and the speed at which the engine is running. At high speeds the torque is greater. The amount of torque needed to move a car is not always directly related to speed. When a car is traveling at moderate speed on a level road, the engine does not need to supply much torque to keep it going. When the car is starting from a dead stop or moving up a hill, however, the engine must deliver enough torque to get or keep the car moving. Turning speed (revolutions per minute) from the engine may be reduced or increased by gears and thus converted to provide greater torque or greater speed.

The gearshift lever of a car moves shifting forks, which engage or disengage various combinations of gears. These combinations provide more or less torque and speed, and they determine the direction in which the vehicle will move. Most modern cars are equipped with an automatic transmission, which alters the combinations of gears or of torque converters without the movement of a lever by hand.

Drive Shaft

The drive shaft carries the torque from the transmission to the axle. The shaft must be equipped with several universal joints. These permit the axle to move freely up and down or from side to side as the wheels roll over road irregularities.

A sliding, or telescoping, joint also is used on drive shafts. This joint permits the shaft to change its length slightly with the up-and-down movement of the rear axle.

A flexible drive shaft with a minimum number of joints has been used on some cars. This small-diameter shaft is of alloy steel. Vibration and whip of the shaft as it turns are limited by two center bearings mounted around the shaft. A plastic-type coating prevents corrosion.

Differential

The rear end of the drive shaft leads into a bulge in the rear-axle housing where the differential is located. The differential applies power as needed to the wheels while they turn at different speeds on curves.

The difference in speeds is necessary because the outer wheels must travel both farther and faster than the inner wheels when the vehicle is going around a turn. This could not occur if the two wheels were rigidly attached to a solid axle. The two front wheels of an automobile with rear-wheel drive present no problem, as each is mounted on its own spindle and turns independently. The rear wheels, however, drive the car, and they must be attached to a strong axle supplying torque from the engine. The rear axle, therefore, is in two pieces connected through the differential.

In some ways the differential works like planetary gears, for, depending on need, some gears will move slower or faster than others or even remain stationary. The system turns the wheel that is easiest to turn. This aids in turning corners but has other disadvantages.

One of these disadvantages, for example, if one wheel of an automobile is on dry pavement and the other is in slippery mud, the wheel in the mud will spin and the other will remain stationary. To eliminate this problem, a complex controlled slip differential has been developed. It prevents one wheel from slipping while the other is standing still.

Some front-wheel drive and rear-engine cars use a transmission-axle combination called a transaxle. In this arrangement a gearbox or torque converter is positioned so that it will drive the axle directly, eliminating a drive shaft connection. Few cars of this type are currently manufactured.

Suspension System

The suspension assembly is designed to absorb much of the up-and-down movement and tilting from side to side as the wheels move over irregularities in the road. The system keeps the body of the car more or less at an even level as well as relatively free from road shock.

Most cars made in North America use coil springs to provide what is called independent front suspension. This permits each front wheel to move up and down independently. Another system uses a torsion bar—a round, heat-treated steel bar that is sufficiently elastic to twist slightly and act as a spring. Leaf springs usually consist of several layers. A durable single-leaf spring has also been developed. Air or air-oil springs are used on some European cars.

Shock absorbers slow the reaction during compression and rebound of the springs. They are filled with a fluid or use Freon gas in a plastic bag.

Axles and Wheels

A rear axle called a swing axle is free to move or swing as either wheel goes up or down. There are variations of this axle. Rear axles are equipped with differentials as described earlier. Trucks usually have rigid front axles.

Most wheels are disks of steel or aluminum. An early type had spokes; spoked wheels are still used on some sports cars.

Tires

Automobiles use pneumatic (air-filled) tires. In the past they had separate inner tubes to hold air. Today's tires are tubeless, sealed airtight to the wheel rim at the bead (edge of their inner circumference).

Tires may be bias type, belted bias, or belted radial. Bias tires, which were standard through the late 1960s, are made of two, four, or more layers of rayon, nylon, polyester, or other synthetic cords laid at an angle from one bead to another. Successive layers, or plies, alternate in direction to strengthen the tire's body. Belted bias tires are made the same way but have belts of synthetic or fine steel wire just beneath the tread (the part of the tire that touches the road). The belts add strength and stability. A belted radial tire has layers of rubber-coated synthetic cords that are laid straight across the tire from bead to bead and covered along the tread with belts. The radial tire's tread is very stable, therefore making the car easier to control. It also reduces rolling resistance and improves fuel economy.

Braking System

Every car has a service brake system, operated by foot pressure on a pedal while the car is in motion, and a hand-operated emergency brake system employed for parking and as a backup to the service brake system. The service brake system uses fluid forced by pistons through small flexible pipes (brake lines) to transmit the pressure of the driver's foot to the brake mechanisms within each wheel and is, therefore, a hydraulic system. Emergency brakes make use of purely mechanical techniques (cables attached to the brake lever) to stop the car. They are intended to be effective if the hydraulic system fades (loses its braking ability).

Steering System

The recirculating ball steering system involves a worm shaft steering gear at the base of the steering column that turns a Pitman arm, causing a device called the drag link to turn the wheels. A simpler system is rack-and-pinion steering. A pinion gear at the base of the steering column moves a rack, transmitting turning motion to the wheels. Rack-and-pinion steering improves control but is not suitable for larger cars because it requires too much strength. Power steering systems make steering virtually effortless. They employ a hydraulic pump and a power cylinder.

Forerunners of the Automobile

Nicolas Cugnot of France built a three-wheeled steam-powered artillery carriage in 1769. This was probably the first automotive vehicle.

Steam carriages were produced in England during the late 18th and early 19th centuries. In 1786 William Murdock built a three-wheeled steam-driven wagon. Richard Trevithick produced several steam carriages in the early 1800s. Steam-driven carriages, built and operated by Goldsworthy Gurney and by Walter Hancock, transported passengers in the London area during this same period. Hancock's “steam bus,” built in 1832, was in regular service between London and Paddington.

Oliver Evans built the first steam-powered motor vehicle in the United States in 1805. A combination dredge and flatboat, it operated on land and water. Richard Dudgeon's road engine of 1867 could carry ten passengers. It resembled a farm tractor.

Steam Automobiles

Steam-driven automobiles were turned out by some 100 manufacturers during the late 1890s and early 1900s. The most famous of these steam-car makers were Francis E. and Freelan O. Stanley of the United States—twin brothers who developed an automobile called the “Stanley Steamer” in 1897. Steam cars burned kerosene to heat water in a tank that was part of the car. The pressure of escaping steam activated the car's driving mechanism. Perhaps the chief asset of the steam car was its simple power mechanism. It did not have an ignition system or a clutch. No transmission was needed because its engine was connected directly to the wheel axle.

The steam car had some disadvantages, however. Most of these centered in the water tank, also called the “boiler.” It took too long for the water to heat up. In addition there was a constant fear of explosion, though this proved groundless. The popularity of the steam car declined at about the time of World War I. Steam car production came to an end in 1929.

Electric Automobiles

Several experimental, electrically powered automobiles were built in Europe during the 1880s. One of the first “electrics” in the United States was produced by William Morrison in 1891. About 54 United States manufacturers turned out almost 35,000 electric cars between 1896 and 1915—the period of their greatest popularity. The Columbia, the Baker, and the Riker were among the more famous makes.

The electric car ran smoothly and was simple to operate. However, it did not run efficiently at speeds of more than 20 miles per hour and could not travel more than 50 miles without having its batteries recharged. Thus it was limited to city use.

Early Gasoline Automobiles

Gasoline-driven automobiles were developed in Europe. A practical gas engine was designed and built by Étienne Lenoir of France in 1860. It ran on illuminating gas. In 1862 he built a vehicle powered by one of his engines. Siegfried Marcus of Austria built several four-wheeled gasoline-powered vehicles. By 1876 Nikolaus Otto, a German, was perfecting his four-stroke cycle engine (see Internal-Combustion Engine). Two other Germans, Karl Benz and Gottlieb Daimler, built gasoline cars in 1885.

Beginning of the Automobile Industry

By the early 1900s many inventors in the United States were developing new models. In 1893 J. Frank and Charles E. Duryea produced the first successful gasoline-powered automobile in the United States. They began commercial production of the Duryea car in 1896—the same year in which Henry Ford operated his first successful automobile in Detroit.

The first automobile salesroom was opened in New York City in 1899 by Percy Owen. In 1900 the first automobile show was held—also in New York City.

Mass production in the automobile industry was introduced in 1901 by Ransom E. Olds, a pioneer experimenter since 1886. His company manufactured more than 400 of the now historic curved-dash Oldsmobiles in that first year. Each car sold for only $650. Henry M. Leland and Henry Ford further developed mass production methods during the early 1900s. (See also Automobile Industry.)

The Selden Patent

In 1879 George B. Selden, an American attorney, applied for a patent which covered the general features of a gasoline-powered automobile. He received his patent in 1895. In 1903 the Association of Licensed Vehicle Manufacturers was formed by companies who recognized the Selden patent. They agreed to pay Selden a royalty on each car built.

Henry Ford refused to join this association. He sued to break Selden's hold on the industry. After extensive litigation, Ford won. In 1911 a District Court of Appeals held that Selden's patent applied only to a two-stroke cycle engine—not to the Otto engine. This decision permitted all manufacturers to use the Otto engine. It also led to a cross-licensing agreement among most of the American manufacturers. This is administered by the Automobile Manufacturers Association. The association can license any signer of the agreement to use a patent held by another signer. Usually the patent holder has a year of exclusive use first.

Developments of the Early 1900s

The Ford Motor Company was organized in 1903, the General Motors Corporation in 1908, and the Chrysler Corporation in 1925. The first Model T Ford was made in 1908. More than 15 million were to be sold in the next 20 years. The Model T, nicknamed the “flivver” and the “tin lizzie,” was probably more responsible for the development of large-scale motoring than was any other car in automotive history. It also spurred the building of roads and streets in the United States (see Automobile Driving).

Many men contributed to the development of the automobile industry in the United States. These included Elmer and Edgar Apperson, who built a car conceived by Elwood G. Haynes in 1894; the Studebaker brothers, manufacturers of horse-drawn vehicles, who began making motorcars in 1902; David Dunbar Buick, who built his first car in 1903; Frederic J. Fisher, founder of the Fisher Body Company (1908), which became a part of General Motors in 1926; Louis Chevrolet, the Swiss-American who founded the Chevrolet Motor Company in 1911; Charles F. Kettering, who invented the self-starter in 1911; John and Horace Dodge, the bicycle parts producers who founded the Dodge Motor Company in 1914; and Charles W. Nash, an executive with other automobile manufacturers until he founded the Nash Motors Company in 1916.

World War I and After

By 1916 annual passenger-car sales in the United States had reached more than 1¹/₂ million. During World War I the manufacture of automobiles for civilian uses was virtually halted as the industry was mobilized to produce vehicles, motors, and other war matériel for the armed forces.

The automobile assumed a significant new role in the American way of life immediately after World War I. No longer an extravagant novelty, the motorcar was rapidly becoming a necessity rather than a luxury for many American families. By the early 1920s most of the basic mechanical problems of automotive engineering had been solved. Manufacturers then concentrated their efforts on making motorcars safer, more stylish, and more comfortable.

Four-wheel brakes were used in production models in 1920. By the late 1920s safety glass and balloon tires were standard equipment. Steel bodies, hydraulic brakes, and hot-water heaters were also common. In 1919, 90 percent of the passenger cars made were open touring cars and roadsters. In 1929 about 90 percent were closed models.

By the mid-1920s Henry Ford had decided to abandon the three-pedaled Model T and replace it with the Model A, which was to be equipped with a conventional gearshift. The last Model T was produced in May 1927. A slowdown in Model T production had been in effect for several months. The first Model A rolled off the assembly line in October 1927, and several were in the showrooms by Dec. 1, 1927. An enthusiastic public was soon buying thousands. In 1928 the Chrysler Corporation announced the production of its answer to the Model A—a new low-cost automobile called the Plymouth.

Despite the Great Depression, the United States automotive industry continued to make engineering progress. The Chrysler Corporation introduced its airflow streamlined models in 1934. Window defrosters became available in 1936, automatic transmissions in 1937, and sealed-beam headlights were introduced in 1940 before the industry once more went into full-time war production for World War II.

Innovations After World War II

Power steering, power brakes, wraparound windshields, tubeless tires, and automatic window and seat controls were among the innovations developed after World War II. Engines became more powerful—horsepower ratings of 200 or 300 were commonplace. Streamlined contours gave way to the boxier shapes of the 1950s. The 1960s models featured longer silhouettes and more window area.

Small European and Japanese compact cars began to capture a larger share of the American market in the mid-1950s. United States manufacturers introduced their own compacts, but it was not until the fuel crisis of the 1970s that they became significant.

Alternatives to Gasoline

In the 1970s came a renewed interest in automobiles propelled by electric motors powered by storage batteries. Enormous expense and two technological problems prevented widespread adoption. However, General Motors announced in 1990 that it would begin work on a new experimental electric car, called the Impact, that would perform as well as internal- combustion engine vehicles. Electric cars are made and used in limited numbers for light passenger use and for mail delivery.

Some passenger cars have diesel engines, which function differently from gas-burning engines. Diesels use less-expensive fuel and can get 20 to 30 percent more miles or kilometers per gallon. They are high polluters and are noisy, however, so research has gone into solving these problems. Also promising is the stratified-charge engine, which supplies lean and rich fuel mixtures simultaneously to each cylinder.

Ethyl alcohol, or ethanol, has been used in cars for many years, either alone or in combination with gasoline to make gasohol. Ethanol is easy to manufacture from renewable plant sources such as corn and sugarcane. It is neither difficult nor expensive to adjust most automobile engines to burn ethanol. This fuel is used widely in Brazil, which depends heavily on imported oil but produces a large sugar crop. In the Philippines there are cars that burn ethanol distilled from coconut husks.

Ethanol's major disadvantage is its high cost in most countries. It can also cause some damage to metal engine parts in high concentrations and should be used only as a supplement rather than a complete substitute for gasoline. If research and development can reduce the drawbacks of ethanol while gasoline prices continue to rise, it may be used on a broader scale.

Other substitutes for gasoline include methyl alcohol, or methanol, which is distilled from wood products or natural gas, and synthetic fuels that can be made from coal, oil, shale, or tar sands. Electric cars would eliminate the need for gasoline entirely, but they face technological obstacles before they can be used widely.

Reducing Pollution

Government regulations have reduced automotive air pollution by forcing the adoption of lead-free gasoline and catalytic converters. Newer engines that burn fuel more efficiently can reduce the volume of emissions while they economize on gasoline.

In the United States, Congress passed the Clean Air Act of 1990, calling for reductions of some auto emissions by as much as 70 percent. California introduced the strictest auto emission standards in the world. The goal was to decrease output of hydrocarbons by 70 percent in new cars by the year 2003.

Increased Safety

In response to legislative requirements, automakers have made many improvements. Disk brakes, for example, are safer than most others because they are less prone to fading, or loss of braking ability. Anti-lock braking systems (ABS), which control skidding on roads during hard braking, are often available. Impact-absorbing bumpers are now standard on many cars. Makers have investigated the crashworthiness of their vehicles and have developed models that have a rigid central box to protect passengers.

All cars are equipped with seat belts, and many have an alarm that warns the driver to fasten them before starting the vehicle. One alternative to seat belts is the air bag. This has a sensor that in a crash activates a gas cylinder in one tenth of a second. The cylinder inflates a nylon bag positioned so that it will prevent a passenger from pitching forward.

Other safety research has centered on improvements in exterior body design to reduce injuries to pedestrians. Electronic instrumentation has been improved so that drivers are warned of unsafe conditions such as an unfastened door.

Fuel Efficiency

Much work goes into transmission improvements. Manual transmissions with four or five speeds are roughly 10 percent more efficient than automatic transmissions. Makers also try to improve automatic transmission performance. A possible substitute for current transmissions is the continuously variable transmission (CVT), which has an infinitely variable set of gears for close matching between engine speed and engine load. Laboratory models indicate a possible savings of as much as 20 percent.

Turbochargers, which force the air-fuel mixture into the cylinder with the pressure of exhaust gases, have been modified from racing cars in which they were first used. Turbochargers improve mileage from 5 to 10 percent. Other possible means to improve economy include styling to reduce wind resistance, improvements in tires, more efficient accessories, and better ignition control. Almost anything that reduces the overall weight of a car will allow it to travel farther on a gallon of fuel.

Better Manufacturing

Research and development in automobile manufacturing are centered on substituting machines for labor and the employment of better materials. One recent manufacturing technique is the use of robotic arms for welding, painting, and assembling automobiles and parts. Plastics have been used as substitutes for metal in many parts of automobiles. As technology has advanced, early durability problems with plastics have been overcome. Because plastic weighs less than metal, its use also saves fuel. Ceramic materials were of interest as possible replacements for engines or engine parts.

Styling for Efficiency

An average-size car traveling at 55 miles (85 kilometers) per hour uses more than 60 percent of its fuel and power to overcome wind resistance. Aerodynamically efficient design greatly reduces the car's drag, improving gas mileage. This information comes from wind tunnel tests on auto bodies.

Better designs are usually considered to be better looking as well. With windshields raked back and a lower hood, a car takes on a dashing, sporty look. Some of the most sensible designs are incidentally attractive. (See also Automobile Industry.)