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machine,arrangement of moving and stationary mechanical parts used to perform some useful workwork,
in physics and mechanics, transfer of energy by a force acting to displace a body. Work is equal to the product of the force and the distance through which it produces movement.
..... Click the link for more information. or to provide transportation. From a historical perspective, many of the first machines were the result of human efforts to improve war-making capabilities; the term engineer at one time had an exclusively military connotation. In the United States the original colonies were not permitted to make or import machine tools; it was only after the Revolution that the first manufacturing machines were built (c.1790) by Samuel Slater for a textile mill in Pawtucket, R.I.
Types of Machines
By means of a machine an applied force is increased, its direction is changed, or one form of motion or energy is changed into another form. Thus defined, such simple devices as the leverlever,
simple machine consisting of a bar supported at some stationary point along its length and used to overcome resistance at a second point by application of force at a third point. The stationary point of a lever is known as its fulcrum.
..... Click the link for more information. , the pulleypulley,
simple machine consisting of a wheel over which a rope, belt, chain, or cable runs.
A grooved pulley wheel like that used for ropes is called a sheave. A single sheave mounted in a block and fixed in place simply changes the direction of force exerted on the rope
..... Click the link for more information. , the inclined planeinclined plane,
simple machine, consisting of a sloping surface, whose purpose is to reduce the force that must be applied to raise a load. To raise a body vertically a force must be applied that is equal to the weight of the body, i.e.
..... Click the link for more information. , the screwscrew,
simple machine consisting essentially of a solid cylinder, usually of metal, around which an inclined plane winds spirally, either clockwise or counterclockwise. It is used to fasten one object to another, to lift a heavy object, or to move an object by a precise amount.
..... Click the link for more information. , and the wheel and axlewheel and axle,
simple machine consisting of a wheel mounted rigidly upon an axle or drum of smaller diameter, the wheel and the axle having the same axis. It is fundamentally a form of lever, the center common to both the wheel and the axle corresponding to the fulcrum, the
..... Click the link for more information. are machines. They are called simple machines; more complicated machines are merely combinations of them. Of the five, the lever, the pulley, and the inclined plane are primary; the wheel and axle and the screw are secondary. The wheel and axle combination is a rotary lever, while the screw may be considered an inclined plane wound around a core. The wedgewedge,
piece of wood or metal thick at one end and sloping to a thin edge at the other; an application of the inclined plane. It is employed in separating two objects from each other or in separating one part of a solid object from an adjoining part, as in splitting wood.
..... Click the link for more information. is a double inclined plane.
Complex machines are designated, as a rule, by the operations they perform; the complicated devices used for sawing, planing, and turning, for example, are known as sawing machines, planing machines, and turning machines respectively and as machine toolsmachine tool,
power-operated tool used for finishing or shaping metal parts, especially parts of other machines. An establishment that is equipped with such tools and specializes in such work is known as a machine shop.
..... Click the link for more information. collectively. Machines used to transform other forms of energy (as heat) into mechanical energy are known as engines, i.e. the steam enginesteam engine,
machine for converting heat energy into mechanical energy using steam as a medium, or working fluid. When water is converted into steam it expands, its volume increasing about 1,600 times. The force produced by the conversion is the basis of all steam engines.
..... Click the link for more information. or the internal-combustion engineinternal-combustion engine,
one in which combustion of the fuel takes place in a confined space, producing expanding gases that are used directly to provide mechanical power.
..... Click the link for more information. . The electric motormotor, electric,
machine that converts electrical energy into mechanical energy. When an electric current is passed through a wire loop that is in a magnetic field, the loop will rotate and the rotating motion is transmitted to a shaft, providing useful mechanical work.
..... Click the link for more information. transforms electrical energy into mechanical energy. Its operation is the reverse of that of the electric generatorgenerator,
in electricity, machine used to change mechanical energy into electrical energy. It operates on the principle of electromagnetic induction, discovered (1831) by Michael Faraday.
..... Click the link for more information. , which transforms the energy of falling water or steam into electrical energy.
Mechanical Advantage and Efficiency of Machines
By means of a machine, a small force, or effort, can be applied to move a much greater resistance, or load. In doing so, however, the applied force must move through a much greater distance than it would if it could move the load directly. The mechanical advantage (MA) of a machine is the factor by which it multiplies any applied force. The MA may be calculated from the ratio of the forces involved or from the ratio of the distances through which they move. Ideally, the two ratios are equal, and it is simpler to calculate the ratio of the distance the effort moves to the distance the resistance moves; this is called the ideal mechanical advantage (IMA). In any real machine some of the effort is used to overcome friction. Thus, the ratio of the resistance force to the effort, called the actual mechanical advantage (AMA), is less than the IMA.
The efficiency of any machine measures the degree to which friction and other factors reduce the actual work output of the machine from its theoretical maximum. A frictionless machine would have an efficiency of 100%. A machine with an efficiency of 20% has an output only one fifth of its theoretical output. The efficiency of a machine is equal to the ratio of its output (resistance multiplied by the distance it is moved) to its input (effort multiplied by the distance through which it is exerted); it is also equal to the ratio of the AMA to the IMA. This does not mean that low-efficiency machines are of limited use. An automobile jack, for example, must overcome a great deal of friction and therefore has low efficiency, but it is extremely valuable because small effort can be applied to lift a great weight.
Although most machines are used to multiply an effort so that it may move a greater resistance, they may have other purposes. For example, a single, fixed pulley merely changes the direction of the applied force; the pulley may make it easier to lift the load, since a person can pull down on a rope, thus adding his or her own weight to the effort, rather than simply lifting the load. In a catapult an effort greater than the load moves through a short distance, causing the load to be moved through a large distance before being released. As the load is being moved, it picks up speed so that it is traveling at a considerable velocity when it leaves the catapult.
a device that performs mechanical motions for the conversion of energy or the processing of materials and information. Three types of machines are distinguished, depending on the basic purpose (the predominant kind of conversion): power, operating, and information machines.
Power machines used for conversion of any kind of energy into mechanical energy are called engines. They include electric motors, turbines, and internal-combustion, piston, and steam engines. Electric generators are also a widely used type of power machine.
Operating machines are subdivided into technological and transportation machines. In technological machines the “material” is the object on which operations are performed (the workpiece, which may be solid, liquid, or gaseous). The processing of material in these machines is a change in shape, properties, state, and position. In transportation machines the “material” is the object being moved; its “conversion” consists only of a change in position. Technological machines include metal working machines, rolling mills, looms, packing machines, typesetting machines, and printing presses. Transportation machines include motor vehicles, diesel locomotives, airplanes, helicopters, elevators, and conveyors.
Information machines are used in data processing. If the information is presented in digital form, the machine is called a calculator or computer (for example, calculators, mechanical integrators, and accounting machines). Strictly speaking, an electronic computer is not a machine, since mechanical motion in it is used only to carry out auxiliary operations (the designation of the computer as a machine was preserved as the historic successor of calculating machines of the arithmometer type).
Machines in which all conversions of energy, material, or information are executed without direct human participation are called automatic machines or simply automatons. The aggregate of automatic machines connected in sequence and used to carry out a certain technological process is an automatic transfer machine. A correctly used machine, particularly an automatic machine, makes human labor easier, increases labor productivity, and ensures high quality of production.
I. I. ARTOBOLEVSKII and N. I. LEVITSKII
A combination of rigid or resistant bodies having definite motions and capable of performing useful work. The term mechanism is closely related but applies only to the physical arrangement that provides for the definite motions of the parts of a machine. For example, a wristwatch is a mechanism, but it does no useful work and thus is not a machine. Machines vary widely in appearance, function, and complexity from the simple hand-operated paper punch to the ocean liner, which is itself composed of many simple and complex machines. See Machinery, Simple machine
machineAny electronic or electromechanical unit of equipment. A machine is always hardware; however, "engine" may refer to hardware or software. See engine.
The term can sound old fashioned or high-tech. For example, when an older generation is subjected to a new technology, a new device is often called a machine. In times past, even a microphone was called a machine. However, "machine language" is 21st century terminology, and "machine architecture," "machine tools" and other "machine" terminology is not at all antiquated.