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simple machinemachine,
arrangement of moving and stationary mechanical parts used to perform some useful work 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
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 consisting essentially of a solid cylinder, usually of metal, around which an 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.
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 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. The ridge forming the inclined plane is called the thread; in cross section the ridge may be approximately triangular, square, or rounded. The vertical distance from any point on one thread to a corresponding point on the next successive thread is called the pitch. A thread can also be placed on the inner surface of a hollow cylinder. Two screws of the same pitch and diameter, one on the outer surface of a solid cylinder and the other on the inner surface of a hollow cylinder, can be arranged so that one may be driven spirally into the other, as in the common nut and bolt. The thread on the surface of the bolt is called the external, or male, screw; that on the inner surface of the nut, the internal, or female, screw. The common jackscrew used to lift automobiles, houses, and other heavy objects is an application of this principle. The internal screw is situated in the base, the external screw on a metal cylinder; at the top of the cylinder a lever or handle is fastened. As the handle is rotated, the external screw moves up the internal screw and the object placed on top of the jack is lifted. The mechanical advantage of the jackscrew, as of any other screw, is theoretically the ratio between the circumference through which the end of the handle moves and the pitch of the screw. Since, however, there is much friction in the operation of a screw, the amount of 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.
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 put into this machine is much greater than the amount done and the efficiency is small. On the other hand, the small effort necessary to turn the handle, when compared to the enormous load raised, makes such a device of great value. The screw is often used for making delicate adjustments of tools and machines, e.g., in the micrometer screw and in the carburetor of the gasoline engine (for regulating the flow of gasoline). The self-tapping screw has notches in the first few threads that can cut female threads in a hollow cylinder. Wood and metal screws, the carpenter's and machinist's vise, the propeller of a boat or airplane, Archimedes' screw, and many other devices are applications of the screw.



a machine part of cylindrical—sometimes conical—shape, with a helical surface; or a part with helical blades. Screws are grouped as follows: screws that interact directly with an external, or working, medium, and screws that interact with a threaded opening of another part. The first group includes screws used for the production of rotary motion from moving gases and liquids (for example, in a wind engine); for the production of a tractive force (for example, an airplane propeller or a screw propeller on a ship); and for moving gases, liquids, and viscous, friable, or lump materials, sometimes with the creation in them of pressure and agitation (for example, in fans, pumps, screw conveyors, screw presses, and stirring screw conveyors). The second group includes motion screws, heavy-duty (force) screws, micrometer screws, fastening screws, and set screws.

A motion screw is the basic part of the screw mechanism in lathes and machines used for the rectilinear movement of assemblies and components (supports, tables, and so on) along a set of guides. Motion screws generally have a trapezoidal thread shape—less frequently square, triangular, or special—for screwing on nuts.

A heavy-duty force screw is a main part of a screw mechanism designed to produce large axial stresses in presses, furnace pushers, jacks (load-lifting screws), and so on. Force screws generally have a trapezoidal or buttress thread, less frequently a square thread. Short force screws, such as those in jacks, work by compression; they are checked for strength and buckling during their design and manufacture. Long force screws work by tension and are tested for tensile strength.

Micrometer screws have a precision thread with a small pitch; they are used in measuring machines, devices, and instruments (for example, in micrometers).

A fastening screw is a basic part of a detachable screw joint; the body of the screw has a threaded shaft at one end and a head at the other end. Fastening screws for metals and other solid materials usually have a triangular cylindrical thread. Noncritical small-diameter (to 8 mm) fastening screws are also made as self-tapping screws, with a tapered portion of partially shaped thread on the point. This type of screw extrudes the thread (in soft metals) or cuts it (in plastics and hard metals) when screwed into a smooth hole. Wood screws, which are used for fastening wooden parts, have a tapered portion of the thread at the point. The screw head serves both as a clamp for the parts to be joined and as a grip for tightening the screw with a screwdriver, wrench, or other tool. Standard fastening screws with hexagonal, square, and other types of heads are widespread.

Setscrews are generally used for the precise clamping of geodetic and other types of instruments, as well as for fastening screws in screw joints. Setscrews differ in the shape of the head and the clamping (adjusting) point.


What does it mean when you dream about a screw?

The dreamer may feel as if they are being turned like a screw in a situation where someone is taking advantage of them.


(design engineering)
A cylindrical body with a helical groove cut into its surface.
A fastener with continuous ribs on a cylindrical or conical shank and a slotted, recessed, flat, or rounded head. Also known as screw fastener.


screw: nomenclature
An externally threaded fastener.


1. a device used for fastening materials together, consisting of a threaded and usually tapered shank that has a slotted head by which it may be rotated so as to cut its own thread as it bores through the material
2. a threaded cylindrical rod that engages with a similarly threaded cylindrical hole; bolt
3. a thread in a cylindrical hole corresponding with that on the bolt or screw with which it is designed to engage
4. Billiards snooker
a. a stroke in which the cue ball recoils or moves backward after striking the object ball, made by striking the cue ball below its centre
b. the motion resulting from this stroke
5. another name for propeller
6. Slang an old, unsound, or worthless horse


(MIT) A lose, usually in software. Especially used for user-visible misbehaviour caused by a bug or misfeature. This use has become quite widespread outside MIT.
References in periodicals archive ?
Drive the anchor right through the drywall with your hammer and tighten the screw to expand the shank.
"We have to tighten the screws until there's no wiggle room left for terrorists or criminals and no means for them to launch attacks," Avramopoulos told Welt.
ISLAMABAD -- As Middle Eastern countries tighten the screws on human resource exports, Pakistan labour export to Saudi Arabia has plunged by 40 percent in 2017, according to official data available from Bureau of Emigration and Overseas Employment (BOEOE).
The humanitarian crisis in Yemen worsens as the regime in Riyadh and its allies tighten the screws on Yemen's ports.
Haley said the US will "tighten the screws" and putting pressure economically, diplomatically, politically and internationally.
He's incredibly concerned about anything and everything around him, I think this was a message to South Korea after the election and so what we're going to do is continue to tighten the screws. He feels it.
The move comes as the regulator looks to tighten the screws on brokerage houses and also "critically reviews the role of statutory auditors of brokerage houses".
Babe starts to tighten the screws on the Coker family
So, the opportunity to tighten the screws won't come until December.
The law -- Maharashtra Control of Organised Crime Act ( MCOCA) -- will enable the police to tighten the screws on the accused as their confessions before the investigators would now be admissible in court.
New York City Public Advocate, Bill de Blasio, who had teamed up with UANI to launch the Iran Watch List, said, 'Consumers here have the power to force these companies out of Iran and tighten the screws on Tehran's regime.
The ministry pointed out that these practices come as a continuation of the fierce attack against the prisoners after the right-winged extremist Israeli government gave the green light to the prison's administration to increase the pressure on the prisoners and tighten the screws, for political gains.