West's Encyclopedia of American Law Science of Everyday ThingsThe Columbia Encyclopedia, 6th ed. Further reading




No invention has so transformed the landscape of the United States as the automobile, and no other country has so thoroughly adopted the automobile as its favorite means of transportation. Automobiles are used both for pleasure and for commerce and are typically the most valuable type of personal property owned by U.S. citizens. Because autos are expensive to acquire and maintain, heavily taxed, favorite targets of thieves, a major cause of air and noise pollution, and capable of causing tremendous personal injuries and property damage, the body of law surrounding them is quite large. Automobile law covers the four general phases in the life cycle of an automobile: its manufacture, sale, operation, and disposal.

Brief History of the Automobile

The first automobile powered by an internal combustion engine was invented and designed in Germany during the 1880s. In 1903, Henry Ford founded the Ford Motor Company and started an era of U.S. leadership in auto production that lasted for most of the twentieth century. In 1908, Ford introduced the highly popular Model T, which by 1913 was being manufactured through assembly line techniques. Innovations by Ford, General Motors, and other manufacturers near Detroit, Michigan, made that city the manufacturing center for the U.S. car industry. By the 1920s, General Motors had become the world's largest auto manufacturer, a distinction it still held into 2004. Over time, the auto industry in all countries became increasingly concentrated in the hands of a few companies, and by 1939, the Big Three—Ford, General Motors, and Daimler Chrysler—had 90 percent of the U.S. market. As of 2003, Ford is the world's second-largest auto manufacturer after General Motors Corporation.

What to Do If You Are in an Auto Accident

Sooner or later, you are likely to have an accident. Fortunately, it will probably be a minor collision that damages only the vehicles involved. However, whether you are in a minor or major accident, behaving coolly, calmly, and properly after it occurs could save you a lot of money and trouble.

Some suggestions on what to do if you are in an auto accident:

  1. If possible, move your car to the side of the road or out of the way of traffic.
  2. Turn on your car flashers or set up flares to warn other motorists of the accident.
  3. Do not make any statements concerning who was at fault, or assign blame to anyone involved.
  4. Help any persons who are injured. Most states have laws requiring you to render aid to anyone injured in the accident. Call an ambulance if necessary.
  5. Write down the name, address, license plate number, and driver's license number of the other driver and ask to see his or her vehicle registration certificate and proof of insurance. Write down the insurance company name and policy number of the other driver. If asked, do the same for the other driver. Do not reveal the amount of your insurance coverage.
  6. Write down the names and addresses of all passengers involved and of any witnesses to the accident.
  7. Notify the police, particularly if anyone is hurt or injured at the scene.
  8. Write down the names and badge numbers of any police officers at the scene.
  9. If possible, take a picture of the scene of the accident, including damage to cars and skid marks.
  10. Draw a rough diagram of what happened in the accident, noting road conditions, weather, and lighting.
  11. If you suspect you have any injuries, obtain medical care.
  12. Talk to a lawyer if you intend to file a lawsuit regarding the accident.

All states require those involved in an accident to file a report with the police or bureau of motor vehicles if the accident involves a death, a personal injury, or property damage above a certain amount, such as $500. Some states require that the report be made immediately; others allow five to thirty days. Failure to file a report is a misdemeanor in most states and could result in the suspension of your driver's license.

Some insurance companies provide their policyholders with accident report forms. Such forms make it easier to obtain the necessary information if you are in an accident. If you have them, keep them handy in your vehicle.

In 1929, there were roughly 5 million autos in the United States. All those cars required an infrastructure of roads, and by the end of world war ii, the federal government had begun aggressively to fund highway development. With the intention of improving the nation's ability to defend itself, Congress passed the Federal-Aid Highway Act of 1944 (58 Stat. 838). It authorized construction of a system of multiple-lane, limited-access freeways, officially called the National System of Interstate and Defense Highways, designed to connect 90 percent of all U.S. cities of 50,000 or more people. In 1956, the Federal-Aid Highway Act (23U.S.C.A. § 103 [West 1995]) established the Federal Highway Trust Fund, which as of the early 2000s continued to provide 90 percent of the financing for interstate highways. By 1990, the interstate highway system was 99.2 percent complete and had cost $125 billion.

During the 1970s, the U.S. auto industry began to lose ground to Japanese and European automakers, and U.S. citizens relied to an increasing degree on imported autos. Japan, for example, surpassed the United States in auto production in the 1970s. Oil shortages and embargoes during the 1970s caused the price of gasoline to rise and put a premium on smaller autos, most of which were produced by foreign companies. Foreign cars also earned a reputation for higher quality during this period. The share of foreign cars in the U.S. market rose from 7.6 percent in 1960 to 24.9 percent in 1984.

In the early 1980s, the U.S. auto companies were suffering greatly, and the U.S. government bailed out the nearly bankrupt Chrysler Corporation. The U.S. government also negotiated a quota system with Japan that called for limits on Japanese autos imported into the United States, thereby raising the prices of Japanese cars. By the 1990s, the U.S. auto companies had regained much of the ground lost to foreign companies. In the mid-1990s, however, international manufacturing agreements meant that few cars, U.S. or foreign, were made entirely in one country.

Unsafe at Any Speed

For over half a century the automobile has brought death, injury, and the most inestimable sorrow and deprivation to millions of people." So ralph nader began his 1965 book Unsafe at Any Speed: The Designed-in Dangers of the American Automobile, a landmark in the history of U.S. consumer protection.

Nader's book recounts how U.S. automobile manufacturers resisted attempts to improve auto safety in the 1950s and 1960s. Even when makers of other vehicles such as planes, boats, and trains were forced to adhere to safety regulations, automakers were still largely uncontrolled in the area of safety. "The gap between existing design and attainable safety," Nader wrote, "has widened enormously in the postwar period."

Nader examined how auto companies lobbied against safety regulation and organized public relations campaigns that asserted over and over again that most injuries were the result of driver error. He argued that the best and most cost-effective way to reduce auto injuries is not to try to alter driver behavior—as honorable a goal as that might be—but to require automakers to design cars that better prevent accidents from occurring and better protect passengers if accidents do occur.

In telling his story, Nader cited sobering statistics on traffic injuries and fatalities, including the fact that auto accidents caused the deaths of 47,700 in 1964—

"the extinguishment of about one and three-quarter million years of expected lifetimes," he noted—and one-third of all hospitalizations for injuries and 25 percent of all cases of partial and complete paralysis due to injury. Borrowing the zeal and spirit of the civil rights reform movement and the faith in technology of the space program, Nader looked at traffic fatalities as a public health issue that can be resolved through public action and technological innovation. Quoting Walt Whitman's epigram "If anything is sacred, the human body is sacred," Nader asserted that he was attempting to protect the "body rights" of U.S. citizens.

To protect those rights, Nader used his book to call for a number of different strategies to reduce traffic fatalities and injuries: federal safety standards; a federal facility for auto safety research, design, and testing; increased manufacturer research and development for safety technology; improved consumer information with regard to auto safety; better disclosure of auto manufacturers' safety engineering efforts; and the creation of a department of transportation. It is a mark of Nader's foresight and determination that all of those goals were achieved in the decades following the publishing of Unsafe at Any Speed.


Nader, Ralph.


Throughout the twentieth century, automakers were required to conform to ever stricter standards regarding the manufacture of their vehicles. These rules were designed to improve the safety, fuel consumption, and emissions of the auto.

Safety Standards As autos increased in number and became larger and faster, and people traveled more miles a year in them, the number of motor vehicle deaths and injuries rose. By 1965, some 50,000 people were being killed in motor vehicle accidents every year, making automobiles the leading cause of accidental death for all age groups and the overall leading cause of death for the population below age 44. Between 1945 and 1995, 2 million people died and about 200 million were injured in auto accidents—many more than were wounded and injured in all the wars in the nation's history combined.

Beginning in the 1960s, consumer and automobile safety advocates began to press for federal safety standards for the manufacture of automobiles that would reduce such harrowing statistics. The most famous of these advocates was ralph nader, who published a 1965 book on the deficiencies of auto safety, called Unsafe at Any Speed: The Designed-in Dangers of the American Automobile. From 1965 to 1995, more than 50 safety standards were imposed on vehicle manufacturers, regulating the construction of windshields, safety belts, head restraints, brakes, tires, lighting, door strength, roof strength, and bumper strength.

In 1966, Congress passed the National Traffic and Motor Vehicle Act (15 U.S.C.A. § 1381 note, 1391 et seq. [1995]), which established a new federal regulatory agency, the National Highway Safety Bureau, later renamed the National Highway Traffic Safety Administration (NHTSA). NHTSA was given a mandate to establish and enforce rules that would force manufacturers to build vehicles that could better avoid and withstand accidents. It was also given the power to require manufacturers to recall and repair defects in their motor vehicles and the authority to coordinate state programs aimed at improving driver behavior. Also in 1966, Congress passed the Highway Safety Act (23 U.S.C.A. §§ 105, 303 note, et seq. [1995]), which provided for federal guidance and funding to states for the creation of highway safety programs.

As a result of these new laws, 19 federal safety regulations came into effect on January 1, 1968. The regulations specified accident avoidance standards governing such vehicle features as brakes, tires, windshields, lights, and transmission

controls. They also mandated more costly crash-protection standards. These included occupant-protection requirements for seat belts, energy-absorbing steering wheels and bumpers, head restraints, padded instrument panels, and stronger side doors. These auto safety standards significantly reduced traffic fatalities. Between 1968 and 1979, the annual motor vehicle death rate decreased 35.2 percent, from 5.4 to 3.5 deaths per 100 million vehicle miles.

The seat belt requirement is usually considered the most important and effective safety standard. According to one study, seat belts that attach across both the lap and the shoulder reduce the probability of serious injury in an accident by 64 percent and of fatalities by 32 percent for front-seat occupants. However, because people do not always use restraints that require their active participation, autos began to be required to have passive restraint systems such as automatic seat belts and air bags. Air bags pop out instantly in a crash and form a cushion that prevents the occupants from hitting the windshield or dashboard. These devices can substantially reduce the motor vehicle death rate. Cars made after 1990 must have either automatic seat belts or air bags, for front-seat occupants.

However, many auto safety experts point out that regulations on the manufacture of automobiles can only go so far in reducing injuries. Studies indicate that only 13 percent of auto accidents result from mechanical failure, and of those that do, most are caused by poor maintenance, not inadequate design or construction. Other analysts assert that safety regulations cause a phenomenon known as offsetting behavior. According to this theory, people will drive more dangerously because they know their risk of injury is lower, putting themselves, their passengers, and other drivers, passengers, and pedestrians at greater risk and thereby offsetting the gain in safety caused by stricter manufacturing standards.

The NHTSA may also authorize recalls of cars on the road that it deems are safety hazards. In a recall, the federal government mandates that a manufacturer must repair all the vehicles that it has made that have a specific problem.

Between 1976 and 1980, the NHTSA authorized the recall of over 39 million vehicles. Recall is a controversial policy. One problem with it is that, typically, only 50 percent of auto owners respond to recall notices.

No-Fault Automobile Insurance

Ever since the invention of automobiles, there have been automobile accidents. And with those accidents have come legal disputes about who was most at fault in causing them—and who should be forced to pay damages. The U.S. legal and political systems have struggled to determine the best way to handle the large number of legal disputes related to automobile accidents. Although the states vary in their procedures, two basic approaches have evolved. The first and older approach is the traditional liability litigation system, which attempts to determine, usually through jury trials, who is more liable, or more at fault, and must pay damages. The second and more recent approach is no-fault insurance, which simply allows each party to be compensated, regardless of fault, by its own insurance company for accident damages. Both approaches have their advantages and disadvantages, and the debate about which is better continues.

The traditional liability litigation system developed out of the English common law. Under this system, anyone who suffers an injury from a wrong or negligent act of another is free to sue the other party for damages. For example, someone who is paralyzed in an automobile accident and becomes confined to a wheelchair may sue the other driver or drivers involved in the accident. Whether or not the injured person receives payment for those damages is largely dependent on a determination of who was more at fault in causing the accident. If, in a court of law, it is determined that the other driver is at fault, then the injured person may collect a large sum from the other driver or, if the other driver has liability insurance, from the other driver's insurance company; if it is determined that the other driver is not at fault, the injured person may not receive any payments beyond those from her or his own insurance company.

This system of resolving disputes is also called the tort litigation process. In relation to automobile accidents, a tort is a civil (as opposed to criminal) wrong that causes an accident—for example, failure to practice caution while driving, thus causing a collision with another car and injuries to its passengers.

As time passed and auto accidents became more frequent, some people began to point out problems in the liability litigation system for resolving accident disputes. They noted that, owing to the complicated nature of many automobile accidents, it often took a great deal of time to determine who was at fault. As a result, many accident victims had to wait a considerable period before they could receive adequate compensation for their injuries. Other victims who may have been unable to work because of injuries, frequently settled for smaller amounts or even waived their right to a trial, in order to receive faster payment from insurance companies. Other critics of the liability litigation process claimed that the awards granted in auto accident cases varied greatly. Some people were overpaid, and others underpaid, for their damages. A better system, critics maintained, would make all drivers share in the cost of accidents. These critics began to press for a no-fault insurance system as an alternative to liability litigation.

As early as 1946, the Province of Saskatchewan, Canada, enacted no-fault auto insurance. Under a no-fault system, those involved in an accident are compensated for their physical injuries up to a certain limit; even the driver who causes the accident is paid for damages. In its purest form, no-fault automobile insurance does not allow those involved in an accident to sue each other, nor can any party recover damages for pain and suffering. However, no-fault plans are often combined with traditional liability systems to allow accident victims to sue when damages exceed a certain threshold. For example, in New York, it is possible to sue to recover for economic damages greater than $50,000 or for pain and suffering because of death or serious injury. No-fault insurance plans are always compulsory, and every driver who wishes to register a vehicle must obtain at least the minimum standard of no-fault insurance.

In the United States, no-fault automobile insurance was first enacted by Massachusetts in 1971 (Mass. Gen. Laws Ann. ch. 90 § 34A et seq. [West 1995]) in response to public dissatisfaction with long, drawn-out, and expensive court cases for compensation of losses suffered in traffic accidents. In the same year, Congress considered no-fault as a comprehensive national automobile insurance plan, but the proposal never became law. That unsuccessful bill evolved into the National Standards for No-Fault Insurance Plans Act, which would have set federal standards for state no-fault insurance laws. It too did not pass. Opponents of the bill claimed that the states should be allowed to experiment with this new approach before a national plan was adopted. By the mid-1990s, roughly half the states had enacted no-fault insurance plans.

In arguing for no-fault insurance, advocates pointed out a number of advantages, including faster benefits payment and more equal damages awards to accident victims. They claimed that no-fault insurance would reduce the number of traffic-related court cases, thereby freeing up the courts to consider other cases. No-fault, they argued, would also reduce the cost of car insurance premiums as the legal costs associated with settling auto-related cases decreased. Since the establishment of no-fault insurance in many states, no-fault advocates have bolstered their cause even more by pointing to statistics showing that no-fault plans increase the percentage of insurance benefits payments that go to victims rather than to lawyers and court costs. According to those statistics, in states without no-fault insurance, only forty-eight cents of each dollar spent for insurance premiums goes to those injured in accidents, whereas thirty-two cents goes to court costs and lawyers' fees. However, under the no-fault system in force in Michigan, for example, seventy-three cents of each insurance premium dollar goes to accident victims and four cents goes to court costs and lawyers' fees (Carper 1992).

On the other side of the issue, critics make a number of different points against no-fault insurance. Many, including trial lawyers and some consumer advocates, object to no-fault insurance's elimination of or substantial restrictions on the right to sue for damages. Many states, for example, allow injured parties to sue for "pain and suffering" only if they have sustained specific injuries such as dismemberment, disfigurement, or fracture. Often, "soft-tissue" injuries like whiplash are not allowed as adequate grounds for a lawsuit. Critics also maintain that no-fault insurance takes away the incentive to drive safely. Under the system of no-fault insurance, careless, negligent drivers are entitled to the same compensation in an accident as are careful, responsible drivers. In addition, critics of no-fault insurance cite evidence that the system has not reduced insurance premiums. Under no-fault plans, they argue, the number of persons receiving benefits payments has increased, thus offsetting the reduction in legal costs.

It remains to be seen whether no-fault insurance will continue to spread to other states. Nevada and Pennsylvania have tried no-fault insurance plans and repealed them, with Nevada returning to a financial responsibility law and mandatory liability and property damage insurance. California has considered no-fault insurance for many years but has never adopted it. Some states are looking at compromise plans that preserve elements of both the traditional liability litigation system and the no-fault system. These plans, such as the one in New York, compensate all accident victims, regardless of fault, for basic economic losses—including medical and hospital expenses and lost wages or services—and in the process eliminate small cases where litigation is least cost-effective. At the same time, such plans preserve the right to sue for damages in cases of death or serious injury or when damages exceed a certain amount.

In the end, the question of how to handle auto accident disputes will be decided on the basis of which system—liability litigation, no-fault insurance, or a compromise between the two—is deemed better at limiting costs and at the same time preserving the value of fairness that underlies the U.S. system of justice.

further readings

Lascher, Edward L., Jr., and Michael R. Powers, eds. 2001. The Economics and Politics of Choice No-Fault Insurance. Boston: Kluwer Academic Publishers.

Liao, Y-Ping, and Michelle J. White. 2002."No-Fault for Motor Vehicles: an Economic Analysis." American Law and Economics Review 4 (fall): 258–94.

Mandell, Mark S. 1999. "What's Wrong with Auto No-Fault: S. 625, the Auto-Choice Reform Act." Trial Lawyers Quarterly 29 (winter): 31–42.

Schwartz, Gary T. 2000. "Auto No-Fault and First-Party Insurance: Advantages and Problems." Southern California Law Review 73 (March): 611–75.


Insurance; Tort Law.

Emissions Standards Emissions standards are intended to reduce the amount of pollution coming from a car's exhaust system. Autos are major contributors to air pollution. Some cities, such as Los Angeles, have notorious problems with smog, a situation that can cause serious health problems for those with respiratory problems such as asthma and bronchitis. Air pollution also damages plants, reduces crop yields, lowers visibility, and causes acid rain. In 1970, Congress passed the Clean Air Act Amendments (Pub. L. No. 91-604, 84 Stat. 1676–1713 [42 U.S.C.A. § 7403 et seq. (1995)]), which set an ambitious goal of eliminating, by 1975, 90 to 95 percent of the emissions of hydrocarbons, carbon monoxide, and oxides of nitrogen as measured in 1968 automobiles. Manufacturers did not meet the target date for achieving this goal, and the deadline was extended. Also, the new emissions standards caused problems because they reduced fuel economy and vehicle performance.

Congress modified emissions standards in the 1977 Clean Air Act Amendments (42U.S.C.A. § 7401 et seq.) and in the Clean Air Act Amendments of 1990 (Pub. L. No. 101-549, 104 Stat. 2399 [42 U.S.C.A. § 7401 et seq. (1995)]). The modified standards, as defined and monitored by the environmental protection agency (EPA), included new requirements for states with low air quality to implement inspection and maintenance programs for all cars. These inspections were designed to ensure that vehicle emissions systems were working properly. In 1992, the EPA implemented strict emissions testing requirements for 18 states and 33 cities with excessive levels of carbon monoxide and ozone.

California has been a leader in setting air quality standards. In 1989, it announced new guidelines that called for the phasing out of gasfueled cars in southern California by the year 2010.

Critics maintain that federal emissions regulations have been too costly and that regulators should focus on reducing the emissions of more significant polluters, such as power plants and factories.

Fuel Efficiency Standards In the 1975 Energy Policy and Conservation Act (Pub. L. No. 94-163, 89 Stat. 871 [codified as amended in scattered sections of 12 U.S.C.A., 15 U.S.C.A., and 42 U.S.C.A.]), Congress created a set of corporate average fuel economy (CAFE) standards for new cars manufactured in the United States. The secretary of transportation was empowered with overseeing these standards. The standards mandated that each car manufacturer achieve an average fuel economy of 27.5 miles per gallon (mpg) for its entire fleet of cars by 1985. Manufacturers that did not achieve these standards were to be fined. In 1980, an additional sales tax at purchase was placed upon "gas guzzlers" (cars that fail to achieve certain levels of fuel economy). The more a car's gas mileage is below a set standard—which was 22.5 mpg in 1986—the greater the tax. For example, a 1986 car that achieved less than 12.5 mpg was charged an additional sales tax of $3,850. Some members of Congress have lobbied for fuel efficiency standards as high as a 40 mpg fleet average for auto manufacturers.

The fleet-average fuel efficiency of cars nearly doubled between 1973 and 1984. However, detractors of fuel efficiency standards maintain that the increase in efficiency was not entirely due to federal standards. They argue that fuel efficiency would have risen without regulation, in response to higher gas prices and consumer demand for more efficient cars.

Import Quotas Faced with increasingly stiff competition from Japan and Europe, U.S. car manufacturers in the early 1980s pressed the federal government to limit the number of foreign cars imported into the United States. The administration of President ronald reagan responded by negotiating quotas, or limits, on Japanese car imports from 1981 to 1985. The Japanese voluntarily continued quotas on their car exports through the late 1980s, and quotas on pickup trucks from Japan remained in effect through the mid-1990s.

Tort Law and Automobile Manufacturing Courts have established that manufacturers may be held liable and sued for property damage and personal suffering caused by the products they have manufactured. Automobile manufacturers, like all manufacturers, are thus subject to product liability law. Anyone who suffers harm, injury, or property damage from an improperly made auto may sue for damages. Actions that involve a breach of the manufacturer's responsibility to provide a reasonably safe vehicle are called torts.

Courts have found that auto manufacturers have a duty to reasonably design their vehicle against foreseeable accidents. The most important legal concept in this area is crashworthiness—a manufacturer's responsibility to make the car reasonably safe in the event of a crash. The standard of crashworthiness makes it possible to hold manufacturers liable for a defect that causes or enhances injuries suffered in a crash, even if that defect did not cause the crash itself. Auto injuries are often the result of a "second collision," when the occupant's body strikes the interior of the car or strikes an exterior object after being thrown from the vehicle. Second collisions can occur when the seat belt fails, for example. Other examples of failures in crash-worthiness include instruments that protrude on a dashboard or a fuel tank that explodes after impact. A landmark case in this area of manufacturer liability is Larsen v. General Motors Corp., 391 F.2d 495 (8th Cir. 1968), in which an individual was compensated for injuries suffered when his head struck a steering wheel in an accident. In another significant case, Grimshaw v. Ford Motor Co., 119 Cal. App. Ct. 3d 757, 174 Cal. Rptr. 348 (1981), a California jury required Ford Motor Company to pay $125 million in punitive damages (later lowered to $3.5 million) to a teenager who was severely burned in a fire that resulted when his Ford Pinto was rear-ended and the fuel tank exploded.

Automakers may also be held liable for failure to warn of a product's dangerous tendencies. Manufacturers have, for example, been sued for failing to warn drivers that certain vehicles had a tendency to roll over in some conditions.

One of the more high-profile cases involving defects in automobiles and their parts involved Ford Motor Company and the tire manufacturer Bridgestone/Firestone. On May 2, 2000, the NHTSA began an investigation involving Firestone tires. By that time, the agency had received 90 complaints from consumers who had suffered accidents because the tread on the tires of their Ford Explorers had allegedly caused their vehicles to roll over. These accidents had resulted in at least 27 injuries and four deaths. On August 9, 2000, Bridgestone/Firestone announced the recall of 6.5 million tires, many of which were standard equipment on Explorers.

Ford and Bridgestone/Firestone eventually faced more than 1,000 lawsuits in state and federal court. Many of these cases were settled, including several cases that had been followed closely by the national media. In one case, Marisa Rodriguez of Texas suffered permanent paralysis in 1998 when a faulty tire in the Ford Explorer in which she was riding caused the vehicle to roll over. Rodriguez sought damages of $1 billion when she brought suit in the U.S. District Court for the Southern District of Texas, though she eventually settled the case for a reported $6 million.

By 2002, the total number of fatalities had increased to more than 271, with more than 1,000 injuries. By February 2003, several class action and other suits were pending against Bridgestone/Firestone. In 2001, Congress conducted a series of hearings investigating the Ford and Bridgestone/Firestone fiasco. Congress eventually enacted the Transportation Recall Enhancement, Accountability, and Documentation Act, Pub. L. No. 106-414, 114 Stat. 1800 (49U.S.C.A. §§ 30101 et seq.). It provides criminal penalties for misleading the Secretary of Transportation with respect to vehicle and equipment-related safety defects. Although the provisions of the statute do not apply to the Firestone/Ford cases.

Sale, Lease, and Rental

When shopping for a car, consumers generally receive their first information through advertising. States regulate automobile ads in different ways. In some states, an ad must state

the number of advertised vehicles available for sale, the price, the dealer, and the factory-installed options and warranty terms. Car buyers should beware of bait-and-switch advertising, in which a dealer advertises a specific car for sale without the intention of actually selling it. The ad lures the customer into the showroom so that she or he may be persuaded to buy a higher-priced, unadvertised vehicle. When buyers encounter this type of fraud, or any other type of consumer fraud, they should contact the consumer protection division of their state attorney general's office.

The statute of frauds of the uniform commercial code (UCC) governs the sale of autos in every state except Louisiana. According to the UCC, an auto contract must be in writing in order to be considered valid in court. The purchaser and an agent of the seller—an authorized salesperson, supervisor, or manager—must sign the contract. Buyers should read all terms of the contract before signing. The contract should specify whether the car is new or used and include a description of the car, the car's vehicle identification number (VIN) (on the driver's side of the dashboard near the window), details of any trade-in, and the terms of financing, including the annual percentage rate.

In most states, the title for a new or used car passes to the buyer when the seller endorses the certificate of title. If the buyer does not maintain payments according to the finance agreement, the creditor can repossess the car as collateral for the loan. The debtor has the right to buy back the car (redeem the collateral) and can do so by paying the entire balance due plus repossession costs. Eventually, the creditor may sell the car to another party. If the profit from the sale does not satisfy the debt, the debtor is liable for the difference. If the profit from the sale is greater than the debt, the creditor must pay the difference to the debtor. In some states, the creditor is required by the UCC to notify the debtor of the time, place, and manner of any sale of the car.

All used-car dealers must attach a buyer's guide to the side window of any car they are selling. It must state whether the car comes with a warranty; outline the specific coverage of any warranty; recommend that an independent mechanic inspect the car; state that all promises should be put in writing; and provide a list of potential problems with the car. The buyer's guide becomes part of any contract with the seller. The seller must be truthful about the car and should provide the buyer with the car's complete service records and a signed, written statement of the odometer reading and its accuracy. If the car does not perform as promised, a breach of warranty may have occurred. If an individual pays more than $500 for a used car, he or she should have a written contract and a bill of sale. The latter is required in many states to register a car and should include the date of sale; the year, make, and model of the car; the VIN; the odometer reading; the amount paid for the car and what form it took; the buyer's and seller's names, addresses, and phone numbers; and the seller's signature.

The sale of new automobiles is subject to what are popularly called lemon laws. Lemon is the slang term for a car that just does not work right. Lemon laws, in force in all states as of 2003, entitle a car buyer to a replacement car or a refund if the purchased car cannot be satisfactorily repaired by the dealer. States vary in their requirements for determining whether a car is a lemon. Most define a lemon as a vehicle that has been taken in at least four times for the same repair or is out of service for a total of 30 days during the coverage period. The coverage period is usually one year from delivery or the duration of the written warranty, whichever is shorter. The owner must keep careful records of repairs and submit a written notice to the manufacturer stating the problems with the car and an intention to declare it unfit for use. Many states require that the buyer and the manufacturer or dealer submit to private arbitration, a system of negotiating differences out of court. Increasingly, states are passing lemon laws for used as well as new cars.

A popular method of purchasing the use of a car is leasing. Leasing is essentially long-term rental. For persons who drive few miles a year, like to change cars often, or use their cars for business, leasing is an attractive option. A lease contract may or may not include other expenses such as sales tax, license fee, and insurance. In a closed-end, or "walkaway," lease contract, the car is returned at the end of the contract period and the lessee is free to "walk away" regardless of the value of the car. In an open-end lease, the lessee gambles that the car will be worth a stated price at the end of the lease. If the car is worth more than that price, the lessee may owe nothing or may be refunded the difference; if the car is worth less, the lessee will pay some or all of the difference. Payments are usually higher under a closed-end lease than under an open-end lease. Open-end leases more commonly have a purchase option at the end of the lease term.

To lease or rent an auto, an individual must show a valid driver's license and, usually, a major credit card. A rental business may require that a customer have a good driving record and be of a certain age, sometimes 25 years old or older. An auto rental, as opposed to a lease, may be as short as one day. A rental company may offer a collision damage waiver (CDW) option, which provides insurance coverage for damages to the rented car. The CDW option does not cover personal injuries or personal property damage.

Operation and Maintenance

The operation of an automobile on a public street or highway is a privilege that can be regulated by motor vehicle laws. The individual states derive authority to control traffic from their police power, but often they delegate this authority to a local police force. On the national level, Congress is empowered to regulate motor vehicles that are engaged in interstate commerce.

Automobile regulations are provided for the safety and protection of the public. The laws must be reasonable and should not impose an extraordinary burden on the owners or operators. Such laws also provide a means of identifying vehicles involved in an accident or a theft and of raising revenue for the state by fees imposed on the owner or operator.

Registration and Licensing Every state requires the owner of a vehicle to possess two documents: a certificate of ownership, or title, and a certificate of registration. Through registration, the owner's name, the type of vehicle, the vehicle's license plate number, and the VIN are all registered with the state in a central government office. On payment of a fee, a certificate of registration and license plates are given to the owner as evidence of compliance with the law. The operator is required to display the license plates appropriately on the car—one on the back of the vehicle and sometimes one on the front and the back—and have the certificate of registration and license in possession while driving and ready to display when in an accident or requested to do so by a police officer. If a driver moves to another state, she or he must register the vehicle in that state within a certain amount of time, either immediately or within 20 to 30 days.

A driver's license is also mandatory in every state. The age at which a state allows a person to drive varies, though it is usually sixteen. Other qualifications for a driver's license include physical and mental fitness, comprehension of traffic regulations, and ability to operate a vehicle competently. Most states require a person to pass a written examination, an eye test, and a driving test before being issued a license. States generally allow an individual with a learner's permit or temporary license to operate a vehicle when accompanied by a licensed driver. This arrangement enables a person to develop the driving skills needed to qualify for a license. A license can be revoked or suspended when the motorist disregards the safety of people and property, when a physical or mental disability impairs driving ability, or if the motorist fails to accurately disclose information on the license application. When the state revokes a person's license, it permanently denies that person the right to drive; when it suspends a license, it temporarily denies the right to drive.

Because teenaged drivers are more likely to cause traffic accidents, several states have adopted systems of graduated driver licensing (GDL). Under this system, teenaged drivers typically first receive a learner's permit for about six months, during which time all driving must be supervised by an adult. During the next stage, an intermediate level, teen drivers may drive without the supervision of an adult during the daytime but cannot drive at night without an adult until the age of 18, and cannot have more than one teenaged passenger in the car during unsupervised driving times. More than 30 states and the District of Columbia have adopted a GDL system.

Traffic Laws Dozens of laws are related to the operation of an automobile, a large number of which vary by state. Minor traffic offenses include parking and speeding violations. More serious traffic offenses are reckless driving, leaving the scene of an accident, and driving without a license. Most states require motorists to file reports with the proper authorities when they are involved in accidents.

Speed limits vary by state. In 1973, during the height of the energy crisis, Congress defined a national speed limit of 55 mph in order to reduce gasoline consumption; the 55-mph limit also had the unintended effect of lowering the traffic fatality rate. Since then, most states have returned to an upper limit of 65 mph. Two types of speed limits are imposed: fixed maximum and prima facie. Under fixed maximum limits, it is unlawful to exceed the stated limit anywhere and at any time. Under prima facie limits, it is possible for a driver to prove in certain cases that a speed in excess of the limit was not unsafe and therefore not unlawful, given the condition of the highway, amount of traffic, and other circumstances.

All states require children riding in automobiles to be restrained using safety belts or safety seats. Most states require adults to wear belts as well, though some require belts only for adults in the front seat. Violation of such laws results in a fine. In 1984, New York became the first state to pass a law making seat belts mandatory for adults.

Driving under the Influence Driving under the influence of alcohol and other drugs is the major cause of traffic deaths in the United States. Drunk drivers kill an estimated 25,000 people a year. States use different terms to describe driving under the influence of mind-altering chemicals, or what is popularly known as drunk driving. These include driving underthe influence (DUI), operating under the influence (OUI), and driving while intoxicated (DWI). To arrest someone for drunk driving, the state must have proof that the person is under the influence of alcohol or other drugs, and the person must be in actual physical control of a vehicle and impaired in the ability to operate it safely. Every state has "implied consent" laws that require those with a driver's license to submit to sobriety tests if a police officer suspects they are intoxicated. These tests may include a field sobriety test (a test at the scene, such as walking a straight line), or blood, breath, or urine tests, usually administered at a police station. Refusal to take a sobriety test can result in suspension of the driver's license. Most states have "per se" laws that prohibit persons from driving if they have a blood-alcohol reading above a certain level. Several states have lowered their per se blood-alcohol limits to 0.08 percent. Penalties vary by state but can be particularly severe for repeat offenders, often involving jail sentences and revocation of driving privileges.

dramshop acts make those who sell liquor for consumption on their premises, such as bars and restaurants, liable for damages caused by an intoxicated patron's subsequent actions. In some states, individuals injured by a drunk driver have used such laws to sue bars and restaurants that served liquor to the driver. "Social host" statutes make hosts of parties who serve alcohol and other drugs liable for any damages or injuries caused by guests who subsequently drive while under the influence.

Several national organizations have been formed to combat drunk driving. These include mothers against drunk driving (MADD) and Students Against Drunk Driving (SADD). The legal drinking age has been raised to 21 in every state, largely in an attempt to reduce drunk driving. Most states also make it illegal to transport an open alcoholic beverage container in a vehicle. Alcohol-related deaths as a proportion of all traffic deaths decreased from about 56 percent in 1982 to 47 percent in 1991.

Other Crimes Criminals both target and use automobiles in a number of different types of crime. Cars have been a favorite object of theft ever since their invention. As early as 1919, the dyer act, or National Motor Vehicle Theft Act (18 U.S.C.A. § 2311 et seq.), imposed harsh sentences on those who transported stolen vehicles across state lines. Car theft remains a serious problem in many areas of the country and is a major contributor to high insurance premiums in many urban areas. In 1994, Congress passed the Motor Vehicle Theft Prevention Act (18U.S.C.A. § 511 et seq.; 42 U.S.C.A. § 13701 note, § 14171 [West 1995]), which established a program whereby owners can register their cars with the government, provide information on where their vehicles are usually driven, and affix a decal or marker to the cars. Owners who register their cars in the program authorize the police to stop the cars and question the occupants when the vehicles are out of their normal areas of operation.

Autos are also frequently used to commit crimes. Drivers whose negligence causes accidents that result in the death of other human beings may be found guilty of manslaughter (the unlawful killing of another without malice aforethought, that is, without the intention of causing harm through an illegal act), including criminally negligent manslaughter, a crime punishable by imprisonment. Two types of crime that have received a great deal of public attention are drive-by shootings, in which occupants of a vehicle fire guns at pedestrians or at people in other cars, and car-jackings, in which criminals hijack, or take over, cars from their owners or operators, often robbing and sometimes killing the victims in the process. Because of the usually random nature of such crimes, the public has called for severe penalties for them. The violent crime control and law enforcement act of 1994 (Pub. L. No. 103-322, 108 Stat. 1796) made killings caused by drive-by shootings or car-jackings punishable by death.

Insurance Most states require the owner to acquire auto insurance or deposit a bond before a vehicle can be properly registered. Insurance provides compensation for innocent people who suffer injuries resulting from the negligent operation of a vehicle. Other states have liability, or financial responsibility, statutes that require a motorist to pay for damages suffered in an accident resulting from his or her negligence and to furnish proof of financial capability to cover damages that he or she may cause in the future. These statutes do not necessarily require vehicle liability insurance.

About half of all states require that licensed drivers carry automobile insurance with liability, medical, and physical damage coverage. Liability insurance protects a vehicle owner against financial responsibility for damages caused by the negligence of the insured or other covered

drivers. It consists of bodily injury, or personal liability protection and property damage protection. Medical payments insurance covers the insured's household for medical and funeral expenses that result from an auto accident. Physical damage insurance consists of collision coverage, which pays for damage to a car resulting from collision, regardless of fault, and comprehensive coverage, which pays for damage from theft, fire, or vandalism. Over 20 states also require that drivers carry coverage to protect against uninsured motorists. Such coverage allows insured drivers to receive payments from their own insurer should they suffer injuries caused by an uninsured driver. Most insurance policies offer a choice of deductible, which is the portion of an insurance claim that the insured must pay. The higher the deductible, the lower the annual insurance premium or payment.

Many states have laws requiring no-fault automobile insurance. Under no-fault insurance, each person's own insurance company pays for injury or damage in an auto accident, up to a certain limit, irrespective of whose fault the accident is. Each person is entitled to payment for loss of wages or salary, not exceeding a certain percentage of the value of such loss or a fixed weekly amount.

No-fault statutes provide that every person who receives personal injury benefits gives up the right to sue for damages. However, a person who is licensed to drive in a state that requires no-fault insurance may sue someone who has caused an accident and who is licensed in another state that does not require no-fault insurance. In some states, a person who has not obtained no-fault auto insurance is personally liable to pay damages. Some states do not abolish liability arising from the ownership, maintenance, or operation of a motor vehicle in certain circumstances, such as those in which the harm was intentionally caused, the injured person has suffered death or serious injuries, or medical expenses exceed a certain limit.

States that do not have compulsory automobile insurance typically have financial responsibility acts. These laws are designed to ensure that negligent drivers who injure others will pay any resulting claims. They require a proof of financial responsibility from drivers involved in an accident. After reporting the accident to a state agency, drivers who do not have adequate insurance coverage must post a cash deposit or equivalent bond of up to $60,000, unless the other driver provides a written release from liability.


The last stage in the life cycle of an automobile is its disposal and recycling. In the United States, between 10 and 12 million cars are disposed of each year. In most cases, the first stage of disposal is handled by a wrecking or salvage yard. Most states require the salvage yard to have the title to an auto before the vehicle can be destroyed and to contact a state agency regarding its destruction. This step helps to prevent the destruction of cars used in crimes. Salvage yards typically must be licensed with a state pollution control agency for hazardous waste disposal. Salvage yards remove parts and items of value that can be recycled from the vehicle, such as batteries and fluids. What is left of the automobile is then sold to a shredder, a business that breaks the car up into small parts and separates the metal from the nonmetal parts. Roughly 25 percent of the auto cannot be recycled and must be disposed of in a landfill. Auto residue to be disposed of in a landfill typically must be tested to see that it meets the standards for disposal of hazardous waste.

further readings

American Automobile Association. 1993. Digest of Motor Laws. Heathrow, Fla.: American Automobile Association.

"Automobiles." 1994. In American Bar Association Family Legal Guide. New York: Random House.

Carper, Donald L., et al. 1995. "Owning and Operating Motor Vehicles." In Understanding the Law. 2d ed. St. Paul, Minn.: West.

Crandall, Robert W., et al. 1986. Regulating the Automobile. Washington, D.C.: Brookings.

Goodman, Richard M. 1983. Automobile Design Liability. 2d ed. Rochester, N.Y.: Lawyers Cooperative.

Haas, Carol. 1991. Your Driving and the Law. Bountiful, Utah: Horizon.

Mashaw, Jerry L., and David L. Harfst. 1990. The Struggle for Auto Safety. Cambridge: Harvard Univ. Press.

Nader, Ralph. 1965. Unsafe at any Speed. New York: Grossman.

Research Institute of America, Inc. 2000. Tax Consequences of Using Autos for Business. New York: Research Institute of America.

Winston, Clifford, et al. 1987. Blind Intersection? Policy and the Automobile Industry. Washington, D.C.: Brookings.


Alcohol; Automobile Searches; Collision; Consumer Protection; Environmental Law; Highway; Import Quotas; Personal Property; Product Liability; Punitive Damages; Title; Transportation Department.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Automobiles." West's Encyclopedia of American Law. 2005. Encyclopedia.com. 24 May. 2016 <http://www.encyclopedia.com>.

"Automobiles." West's Encyclopedia of American Law. 2005. Encyclopedia.com. (May 24, 2016). http://www.encyclopedia.com/doc/1G2-3437700416.html

"Automobiles." West's Encyclopedia of American Law. 2005. Retrieved May 24, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3437700416.html




Torque is the application of force where there is rotational motion. The most obvious example of torque in action is the operation of a crescent wrench loosening a lug nut, and a close second is a playground seesaw. But torque is also crucial to the operation of gyroscopes for navigation, and of various motors, both internal-combustion and electrical.


Force, which may be defined as anything that causes an object to move or stop moving, is the linchpin of the three laws of motion formulated by Sir Isaac Newton (1642-1727.) The first law states that an object at rest will remain at rest, and an object in motion will remain in motion, unless or until outside forces act upon it. The second law defines force as the product of mass multiplied by acceleration. According to the third law, when one object exerts a force on another, the second object exerts on the first a force equal in magnitude but opposite in direction.

One way to envision the third law is in terms of an active eventfor instance, two balls striking one another. As a result of the impact, each flies backward. Given the fact that the force on each is equal, and that force is the product of mass and acceleration (this is usually rendered with the formula F = ma ), it is possible to make some predictions regarding the properties of mass and acceleration in this interchange. For instance, if the mass of one ball is relatively small compared to that of the other, its acceleration will be correspondingly greater, and it will thus be thrown backward faster.

On the other hand, the third law can be demonstrated when there is no apparent movement, as for instance, when a person is sitting on a chair, and the chair exerts an equal and opposite force upward. In such a situation, when all the forces acting on an object are in balance, that object is said to be in a state of equilibrium.

Physicists often discuss torque within the context of equilibrium, even though an object experiencing net torque is definitely not in equilibrium. In fact, torque provides a convenient means for testing and measuring the degree of rotational or circular acceleration experienced by an object, just as other means can be used to calculate the amount of linear acceleration. In equilibrium, the net sum of all forces acting on an object should be zero; thus in order to meet the standards of equilibrium, the sum of all torques on the object should also be zero.


Seesaws and Wrenches

As for what torque is and how it works, it is best discuss it in relationship to actual objects in the physical world. Two in particular are favorites among physicists discussing torque: a seesaw and a wrench turning a lug nut. Both provide an easy means of illustrating the two ingredients of torque, force and moment arm.

In any object experiencing torque, there is a pivot point, which on the seesaw is the balance-point, and which in the wrench-and-lug nut combination is the lug nut itself. This is the area around which all the forces are directed. In each case, there is also a place where force is being applied. On the seesaw, it is the seats, each holding a child of differing weight. In the realm of physics, weight is actually a variety of force.

Whereas force is equal to mass multiplied by acceleration, weight is equal to mass multiplied by the acceleration due to gravity. The latter is equal to 32 ft (9.8 m)/sec2. This means that for every second that an object experiencing gravitational force continues to fall, its velocity increases at the rate of 32 ft or 9.8 m per second. Thus, the formula for weight is essentially the same as that for force, with a more specific variety of acceleration substituted for the generalized term in the equation for force.

As for moment arm, this is the distance from the pivot point to the vector on which force is being applied. Moment arm is always perpendicular to the direction of force. Consider a wrench operating on a lug nut. The nut, as noted earlier, is the pivot point, and the moment arm is the distance from the lug nut to the place where the person operating the wrench has applied force. The torque that the lug nut experiences is the product of moment arm multiplied by force.

In English units, torque is measured in pound-feet, whereas the metric unit is Newtonmeters, or N·m. (One newton is the amount of force that, when applied to 1 kg of mass, will give it an acceleration of 1 m/sec2). Hence if a person were to a grip a wrench 9 in (23 cm) from the pivot point, the moment arm would be 0.75 ft (0.23 m.) If the person then applied 50 lb (11.24 N) of force, the lug nut would be experiencing 37.5 pound-feet (2.59 N·m) of torque.

The greater the amount of torque, the greater the tendency of the object to be put into rotation. In the case of a seesaw, its overall design, in particular the fact that it sits on the ground, means that its board can never undergo anything close to 360° rotation; nonetheless, the board does rotate within relatively narrow parameters. The effects of torque can be illustrated by imagining the clockwise rotational behavior of a seesaw viewed from the side, with a child sitting on the left and a teenager on the right.

Suppose the child weighs 50 lb (11.24 N) and sits 3 ft (0.91 m) from the pivot point, giving her side of the seesaw a torque of 150 pound-feet (10.28 N·m). On the other side, her teenage sister weighs 100 lb (22.48 N) and sits 6 ft (1.82 m) from the center, creating a torque of 600 pound-feet (40.91 N·m). As a result of the torque imbalance, the side holding the teenager will rotate clockwise, toward the ground, causing the child's side to also rotate clockwiseoff the ground.

In order for the two to balance one another perfectly, the torque on each side has to be adjusted. One way would be by changing weight, but a more likely remedy is a change in position, and therefore, of moment arm. Since the teenager weighs exactly twice as much as the child, the moment arm on the child's side must be exactly twice as long as that on the teenager's.

Hence, a remedy would be for the two to switch positions with regard to the pivot point. The child would then move out an additional 3 ft (.91 m), to a distance of 6 ft (1.83 m) from the pivot, and the teenager would cut her distance from the pivot point in half, to just 3 ft (.91 m). In fact, however, any solution that gave the child a moment arm twice as long as that of the teenager would work: hence, if the teenager sat 1 ft (.3 m) from the pivot point, the child should be at 2 ft (.61 m) in order to maintain the balance, and so on.

On the other hand, there are many situations in which you may be unable to increase force, but can increase moment arm. Suppose you were trying to disengage a particularly stubborn lug nut, and after applying all your force, it still would not come loose. The solution would be to increase moment arm, either by grasping the wrench further from the pivot point, or by using a longer wrench.

For the same reason, on a door, the knob is placed as far as possible from the hinges. Here the hinge is the pivot point, and the door itself is the moment arm. In some situations of torque, however, moment arm may extend over "empty space," and for this reason, the handle of a wrench is not exactly the same as its moment arm. If one applies force on the wrench at a 90°-angle to the handle, then indeed handle and moment arm are identical; however, if that force were at a 45° angle, then the moment arm would be outside the handle, because moment arm and force are always perpendicular. And if one were to pull the wrench away from the lug nut, then there would be 0° difference between the direction of force and the pivot pointmeaning that moment arm (and hence torque) would also be equal to zero.


A gyroscope consists of a wheel-like disk, called a flywheel, mounted on an axle, which in turn is mounted on a larger ring perpendicular to the plane of the wheel itself. An outer circle on the same plane as the flywheel provides structural stability, and indeed, the gyroscope may include several such concentric rings. Its focal point, however, is the flywheel and the axle. One end of the axle is typically attached to some outside object, while the other end is left free to float.

Once the flywheel is set spinning, gravity has a tendency to pull the unattached end of the axle downward, rotating it on an axis perpendicular to that of the flywheel. This should cause the gyroscope to fall over, but instead it begins to spin a third axis, a horizontal axis perpendicular both to the plane of the flywheel and to the direction of gravity. Thus, it is spinning on three axes, and as a result becomes very stablethat is, very resistant toward outside attempts to upset its balance.

This in turn makes the gyroscope a valued instrument for navigation: due to its high degree of gyroscopic inertia, it resists changes in orientation, and thus can guide a ship toward its destination. Gyroscopes, rather than magnets, are often the key element in a compass. A magnet will point to magnetic north, some distance from "true north" (that is, the North Pole.) But with a gyroscope whose axle has been aligned with true north before the flywheel is set spinning, it is possible to possess a much more accurate directional indicator. For this reason, gyroscopes are used on airplanesparticularly those flying over the polesas well as submarines and even the Space Shuttle.

Torque, along with angular momentum, is the leading factor dictating the motion of a gyroscope. Think of angular momentum as the momentum (mass multiplied by velocity) that a turning object acquires. Due to a principle known as the conservation of angular momentum, a spinning object has a tendency to reach a constant level of angular momentum, and in order to do this, the sum of the external torques acting on the system must be reduced to zero. Thus angular momentum "wants" or "needs" to cancel out torque.

The "right-hand rule" can help you to understand the torque in a system such as the gyroscope. If you extend your right hand, palm downward, your fingers are analogous to the moment arm. Now if you curl your fingers downward, toward the ground, then your fingertips point in the direction of g that is, gravitational force. At that point, your thumb (involuntarily, due to the bone structure of the hand) points in the direction of the torque vector.

When the gyroscope starts to spin, the vectors of angular momentum and torque are at odds with one another. Were this situation to persist, it would destabilize the gyroscope; instead, however, the two come into alignment. Using the right-hand rule, the torque vector on a gyroscope is horizontal in direction, and the vector of angular momentum eventually aligns with it. To achieve this, the gyroscope experiences what is known as gyroscopic precession, pivoting along its support post in an effort to bring angular momentum into alignment with torque. Once this happens, there is no net torque on the system, and the conservation of angular momentum is in effect.

Torque in Complex Machines

Torque is a factor in several complex machines such as the electric motor thatwith variationsruns most household appliances. It is especially important to the operation of automobiles, playing a significant role in the engine and transmission.

An automobile engine produces energy, which the pistons or rotor convert into torque for transmission to the wheels. Though torque is greatest at high speeds, the amount of torque needed to operate a car does not always vary proportionately with speed. At moderate speeds and on level roads, the engine does not need to provide a great deal of torque. But when the car is starting, or climbing a steep hill, it is important that the engine supply enough torque to keep the car running; otherwise it will stall. To allocate torque and speed appropriately, the engine may decrease or increase the number of revolutions per minute to which the rotors are subjected.

Torque comes from the engine, but it has to be supplied to the transmission. In an automatic transmission, there are two principal components: the automatic gearbox and the torque converter. It is the job of the torque converter to transmit power from the flywheel of the engine to the gearbox, and it has to do so as smoothly as possible. The torque converter consists of three elements: an impeller, which is turned by the engine flywheel; a reactor that passes this motion on to a turbine; and the turbine itself, which turns the input shaft on the automatic gearbox. An infusion of oil to the converter assists the impeller and turbine in synchronizing movement, and this alignment of elements in the torque converter creates a smooth relationship between engine and gearbox. This also leads to an increase in the car's overall torquethat is, its turning force.

Torque is also important in the operation of electric motors, found in everything from vacuum cleaners and dishwashers to computer printers and videocassette recorders to subway systems and water-pumping stations. Torque in the context of electricity involves reference to a number of concepts beyond the scope of this discussion: current, conduction, magnetic field, and other topics relevant to electromagnetic force.


Beiser, Arthur. Physics, 5th ed. Reading, MA: Addison-Wesley, 1991.

Macaulay, David. The New Way Things Work. Boston: Houghton Mifflin, 1998.

"Rotational Motion." Physics Department, University of Guelph (Web site). <http://www.physics.uoguelph.ca/tutorials/torque/> (March 4, 2001).

"Rotational MotionTorque." Lee College (Web site). <http://www.lee.edu/mathscience/physics/physics/Courses/LabManual/2b/2b.html> (March 4, 2001).

Schweiger, Peggy E. "Torque" (Web site). <http://www.cyberclassrooms.net/~pschweiger/rotmot.html> (March 4, 2001).

"Torque and Rotational Motion" (Web site). <http://online.cctt.org/curriculumguide/units/torque.asp> (March 4, 2001).



A change in velocity over a given time period.


A situation in which the forces acting upon an object are in balance.


The product of mass multiplied by acceleration.


The tendency of an object in motion to remain in motion, and of an object at rest to remain at rest.


A measure of inertia, indicating the resistance of an object to a change in its motionincluding a change in velocity.


For an object experiencing torque, moment arm is the distance from the pivot or balance point to the vector on which force is being applied. Moment arm is always perpendicular to the direction of force.


The rate at which the position of an object changes over a given period of time.


The product of momentarm multiplied by force.


A quantity that possesses both magnitude and direction. By contrast, a scalar quantity is one that possesses only magnitude, with no specific direction.


The speed of an object in a particular direction.


A measure of the gravitational force on an object; the product of mass multiplied by the acceleration due to gravity.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Torque." Science of Everyday Things. 2002. Encyclopedia.com. 24 May. 2016 <http://www.encyclopedia.com>.

"Torque." Science of Everyday Things. 2002. Encyclopedia.com. (May 24, 2016). http://www.encyclopedia.com/doc/1G2-3408600075.html

"Torque." Science of Everyday Things. 2002. Retrieved May 24, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3408600075.html

marine engine

marine engine, machine for the propulsion of watercraft. The earliest marine power plants, reciprocating steam engines, were used almost exclusively until the early 1900s. In later ship construction these were largely replaced by the steam turbine and the internal-combustion engine (see also diesel engine). For some applications, notably ferries, electric motors are used to allow greater maneuverability. Steam turbines having 1,000 shaft horsepower and more are used for the most powerful ships. Diesel engines may supply power for vessels ranging in size from small boats to medium-size ships requiring as much as 40,000 total horsepower. Gas turbines and fast diesels usually have a reduction-gear drive making it possible to run them at high speeds (for maximum economy) while the propeller turns at low speeds (for maximum efficiency). Gas turbines have been used experimentally in merchant ships and naval patrol boats. Some submarines, merchant ships, and icebreakers have nuclear power plants in which a nuclear reactor replaces the boiler of a stream turbine plant. Conventional submarines have a diesel-electric drive and run on batteries when submerged. Small boats usually have gasoline outboard engines that clamp on the stern or inboard engines to drive propeller shafts. Shallow-draft boats for use in swamps have aircraft engines and air propellers. A few small boats are propelled by a pumped jet of water. The inboard-outboard motor for small vessels incorporates features of both types: the engine, the reduction gearing, and the vertical propeller shaft compose a self-contained unit that is mounted with the engine inboard, usually just forward of the transom; the gear housing projects through an opening in the transom and the propeller shaft extends down from it. This arrangement makes possible the combination of a relatively large power plant with the convenience and maneuverability of an outboard installation; e.g., the propeller may be tilted up in order to beach the boat.

See C. Miller, Small Boat Engines (1961); J. E. Flack et al., Marine Combustion Practice (1969); K. T. Rowland, Steam at Sea (1971).

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"marine engine." The Columbia Encyclopedia, 6th ed.. 2016. Encyclopedia.com. 24 May. 2016 <http://www.encyclopedia.com>.

"marine engine." The Columbia Encyclopedia, 6th ed.. 2016. Encyclopedia.com. (May 24, 2016). http://www.encyclopedia.com/doc/1E1-marineen.html

"marine engine." The Columbia Encyclopedia, 6th ed.. 2016. Retrieved May 24, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-marineen.html

Facts and information from other sites