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Information about Plain Bearing

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Crankshaft, babbit metal, plain bearing shells
A mechanical bushing is a cylindrical lining designed to reduce friction and wear, or constrict and restrain motion of mechanical parts.

In the electrical field bushings are circular plastic ring fittings that slide or screw onto conduit or connectors to provide protection to the insulated cables that will be pulled through them. Bushings play an important role in assuring the integrity of cables during and after their installation. See Bushing (electrical)

Bushing types

One type of bushing is a hardened threaded fixing hole which allows one assembly to be fixed to another by means of a screw or threaded bolt. The use of a bushing can make assembly easier because it avoids the need for a separate nut and washer on the other side of the fixed material. Bushings can be fitted into sheet material by riveting - often the rivet itself incorporates the bushing.

Plain bearings

A typical plain bearing is made of two parts. For example a rotary plain bearing can be just a shaft running through a hole. A simple linear bearing can be a pair of flat surfaces designed to allow motion, for example a drawer and the slides it rests on.

Plain bearings may carry load in one of several ways depending on their operating conditions, load, relative surface speed (shaft to journal), clearance within the bearing, quality and quantity of lubricant and temperature (affecting lubricant viscosity). If full-film conditions apply, the bearing's load is carried solely by a film of fluid lubricant, there being no contact between the two bearing surfaces. In this condition they are known as fluid bearings. In mix or boundary conditions, load is carried partly by direct surface contacts and partly by a film forming between the two. In a dry condition, the full load is carried by surface to surface contact.

Plain bearings are relatively simple and hence inexpensive. They are also compact, light weight, straightforward to repair and have high load-carrying capacity. However, if operating in dry or boundary conditions plain bearings may wear faster and have higher friction than rolling element bearings. Dry and boundary conditions may be experienced even in a fluid bearing when operating outside of its normal operating conditions, i.e., at startup and shutdown.

A common plain bearing design is to use a hardened and polished steel shaft and a soft bronze bushing. In such designs the softer bronze portion can be allowed to wear away, to be periodically renewed.

Plain 'self-lubricating' bearings utilize porous journals within which a lubricant is held. As the bearing operates and lubricant is displaced from the bearing surface, more is carried in from non-wear parts of the bearing. Dry plain bearings can be made of a variety of materials including PTFE (Teflon), graphite, graphite/metal (Graphalloy) and ceramic. The ceramic is very hard, and sand and other grit which enter the bearing are simply ground to a fine powder which does not inhibit the operation of the bearing.

Solid polymer types

Solid polymer plain bearings are now increasingly popular due to dry-running lubrication-free behaviour. Polymer plain bearings now provide the step from a simple plastic bushing to the proven and tested, and thereby predictable and quickly available, machine component. Solid polymer plain bearings give low weight and corrosion resistance, as well as the freedom from maintenance and lubrication enable a solution for almost all applications.

Managing without lubrication is the dream of every design engineer. With modern materials, polymer plain bearings make this a reality. After research spanning decades, an accurate calculation of the service life of polymer plain bearings is possible today. It is important not to confuse a solid polymer plain bearing with a polymer coated plain bearing, which is a much older technology. Many companies produce bushings which consist of a metal shell which then has a very thin polymer coating (usually PTFE or similar) applied to the inside.

Applications

Bushings are also used to transfer loads from a fastening to a much larger area in the underlying structure, the object being to reduce the strain on individual fibers within the underlying structure.

In a car or other vehicle's suspension, rubber bushings are used to connect the various moving arms and pivot points to the chassis and other parts of the suspension. In order to minimise vibration, wear and transmission of noise, they often incorporate flexible material such as rubber or polyurethane. These bushings often take the form of an annular cylinder of flexible material inside a metallic casing or outer tube. They might also feature an internal crush tube which protects the bushing from being crushed by the fixings which hold it on to a threaded spigot. Many different types of bushing designs exist [1].

See also

External Links

References

Electricity (from New Latin ēlectricus, "amberlike") is a general term for a variety of phenomena resulting from the presence and flow of electric charge. This includes many well-known physical phenomena such as lightning, electromagnetic fields and electric currents,
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A conduit is a general term for a means of conveying something from one location to another or between persons.

Examples of conduits:
  • Waterways (such as rivers and canals)
  • Channels for carrying water or other fluids (such as pipes and aqueducts)

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A bushing is an electrical engineering component that insulates a high voltage conductor passing through a metal enclosure. Bushings appear on switchgear, transformers, circuit breakers and other high voltage equipment.
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screw thread is a helical or tapered structure used to convert between rotational and linear movement or force.

Screw threads have several applications:
  • Fasteners such as wood screws, machine screws, nuts and bolts.

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screw is a shaft with a helical groove or thread formed on its surface and provision at one end to turn the screw. Its main uses are as a threaded fastener used to hold objects together, and as a simple machine used to translate torque into linear force.
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A bolt may refer to one of the following:
  • Fasteners:
  • Bolt or capscrew, see Bolted joint
  • Screw, a cylindrical threaded fastener

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A nut is a type of hardware fastener with a threaded hole. Nuts are almost always used opposite a mating bolt to fasten a stack of parts together. The two partners are kept together by a combination of their threads' friction, a slight stretch of the bolt, and compression of the
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The word washer may refer to one of the following:
  • Washing machine
  • Washer (hardware)
  • Headlamp washers.
  • Mal Washer, an Australian politician

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rivet is a mechanical fastener. Before it is installed it consists of a smooth cylindrical shaft with a head on one end. The end opposite the head is called the buck-tail. On installation the rivet is placed in a pre-drilled hole. Then the tail is "upset" (i.e.
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Fluid bearings are bearings which solely support the bearing's loads on a thin layer of liquid or gas.

They can be broadly classified as fluid dynamic bearings, hydrostatic or gas bearings.
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Fluid bearings are bearings which solely support the bearing's loads on a thin layer of liquid or gas.

They can be broadly classified as fluid dynamic bearings, hydrostatic or gas bearings.
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Steel is an alloy consisting mostly of iron, with a carbon content between 0.02% and 1.7 or 2.04% by weight (C:1000–10,8.67Fe), depending on grade. Carbon is the most cost-effective alloying material for iron, but various other alloying elements are used such as manganese and
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Bronze is any of a broad range of copper alloys, usually with tin as the main additive, but sometimes with other elements such as phosphorus, manganese, aluminium, or silicon. (See table below.) It was particularly significant in antiquity, giving its name to the Bronze Age.
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Teflon is a trademark of DuPont and is commonly used for the chemical compound polytetrafluoroethylene.

Teflon can also refer to:
  • Teflon character
  • John Gotti, nicknamed the Teflon Don
  • Ronald Reagan and Bill Clinton, both nicknamed

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Graphalloy is a tradename for a graphite/metal alloy material used for bearing and electrical contacts. Graphite Metallizing Corp owns this tradename (US, EU and other countries).

This material is used in machinery design and repair where lubrication is not possible.
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ceramic is derived from the Greek word κεραμικός (keramikos). The term covers inorganic non-metallic materials which are formed by the action of heat.
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To meet Wikipedia's ,
capitalizations in this article need to be corrected: (1) All proper names should be capitalized in the body of the text
(2) Use standard capitalization rules for trademarks
(even if the trademark owner encourages special treatment).
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A rubber bushing is a device, primarily used in suspension systems, what separates the faces of two metal objects whilst still allowing a set degree of movement. This movement allows the suspension parts to move freely for example when traveling over a large bump but minimizes
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chassis (plural: "chassis") (IPA: /ˈʃæːsiː, ˈtʃæːsiː/) consists of a framework that supports an inanimate object, analogous to an animal's skeleton, for example in a motor vehicle or a
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Natural rubber is an elastic hydrocarbon polymer that naturally occurs as a milky colloidal suspension, or latex, in the sap of some plants. It can also be synthesized. The entropy model of rubber was developed in 1934 by Werner Kuhn.
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tap is a valve for controlling the release of a liquid or gas. In the British Isles and normally in the Commonwealth the word is used for any everyday type of valve, particularly the fittings that control water supply to bathtubs and sinks. In the U.S.
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journal bearing is a simple bearing in which a shaft, or "journal", rotates in the bearing with a layer of oil or grease separating the two parts through fluid dynamic effects. The shaft and bearing are generally both simple polished cylinders with lubricant filling the gap.
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