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Information about Lubrication

Lubrication occurs when opposing surfaces are separated by a lubricant film. The applied load is carried by pressure generated within the fluid, and frictional resistance to motion arises entirely from the shearing of the viscous fluid. The science of friction, lubrication and wear is called tribology. Lubrication is classified into three major categories:
  1. Hydrodynamic lubrication (HL): Also known as fluid film lubrication. The opposing surfaces are completely separated - like aquaplaning on a road.
  2. Elastohydrodynamic lubrication (EHL or EHD): The opposing surfaces are completely separated and the solid bodies deformed by a major load.
  3. Boundary lubrication: The bodies are not entirely separated, with occasional contact at raised points or 'asperities'.


Lubrication is required for correct operation of engines and many other mechanical systems where parts must slide over each other without seizing.

Solid lubrication

The bodies are separated by a solid substance which is capable of reducing friction and wear (i.e. molybdenum disulphide, graphite, etc.).

See also

A lubricant (colloquially, lube) is a substance (often a liquid) introduced between two moving surfaces to reduce the friction and wear between them. A lubricant provides a protective film which allows for two touching surfaces to be separated, thus lessening the friction
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Friction is the force of two surfaces in contact. It is not a fundamental force, as it is derived from electromagnetic forces between atoms. When contacting surfaces move relative to each other, the friction between the two objects converts kinetic energy into thermal energy, or
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wear is the erosion of material from a solid surface by the action of another solid. The study of the processes of wear is part of the discipline of tribology. There are four principal wear processes:
  1. Adhesive wear
  2. Abrasive wear
  3. Corrosive wear

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Tribology is the science and technology of interacting surfaces in relative motion. It includes the study and application of the principles of friction, lubrication and wear.
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Hydrodynamic (HD) lubrication (or fluid film lubrication) has essential elements:
  1. A Lubricant, which must be a Viscous fluid.
  2. Hydrodynamic flow behavior of fluid between bearing and journal.
  3. The surfaces between which the fluid films move must be convergent.

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Boundary lubrication occurs when a fluid fails to develop into a complete fluid film (i.e. hydrodynamic lubrication, allowing occasional contact between high points, known as asperities, of sliding wear surfaces.
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An engine is something that produces an output effect from a given input. The origin of engineering however, came from the design, building and working of (military "engines") because before such devices came to be employed in battles there were very few mechanical devices used.
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A lubricant (colloquially, lube) is a substance (often a liquid) introduced between two moving surfaces to reduce the friction and wear between them. A lubricant provides a protective film which allows for two touching surfaces to be separated, thus lessening the friction
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A branch of fluid dynamics, lubrication theory is used to describe the flow of fluids (liquids or gases) in a geometry in which one dimension is significantly smaller than the others.
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A bearing is a device to permit constrained relative motion between two parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation.
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Although the word grease originally described the rendered fat of animals, the term is now applied more broadly to mean a lubricant of higher initial viscosity than oil, consisting originally of a calcium, sodium or lithium soap jelly emulsified with mineral oil.
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The acronym OIL can refer to:
  • Output Input Language
  • Office of Infrastructure and Logistics - Luxembourg
  • Ontology Inference Layer or Ontology Interchange Language, an Ontology Infrastructure for the Semantic Web.
  • Oil India Limited.

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