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: A lubricant (colloquially, lube) is a substance (often a liquid) introduced between two moving surfaces to reduce the friction and wear between them. ... For other uses, see Friction (disambiguation). ... In materials science, wear is the erosion of material from a solid surface by the action of another solid. ... Tribology is the science and technology of interacting surfaces in relative motion. ...
Hydrodynamic lubrication (HL): Also known as fluid film lubrication. The opposing surfaces are completely separated - like aquaplaning on a road.
Elastohydrodynamic lubrication (EHL or EHD): The opposing surfaces are completely separated and the solid bodies deformed by a major load.
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. Hydrodynamic lubrication has four essential elements: Lubricant medium, in this case, liquid water. ... Boundary lubrication occurs when a fluid fails to develop into a complete fluid film (i. ... For other uses, see Engine (disambiguation). ...
Solid lubrication
The bodies are separated by a solid substance which is capable of reducing friction and wear (i.e. molybdenum disulphide, graphite, etc.).
A lubricant (colloquially, lube, although this usually refers to personal lubricants) is a substance (usually a liquid) introduced between two moving surfaces to reduce the friction and wear between them.
Sulfur impurities in fuels also provide some lubrication properties, which has to be taken in account when switching to a low-sulfur diesel; biodiesel is a popular diesel fuel additive providing additional lubricity.
In most countries, there are efficient collection processes for used lubricants and the majority of this is used directly as a heavy fuel oil.
The more severe cases of boundary lubrication are defined as extreme pressure conditions; they are met with lubricants containing EP additives that prevent sliding surfaces from fusing together at high local temperatures and pressures.
a system of lubrication in which a metered amount of lubricant or lubricants for the bearing surfaces of a machine or group of machines are supplied from a central location.
The phenomenon observed among gear lubricants and greases when they thicken due to cold weather or other causes, to such an extent that a groove is formed through which the part to be lubricated moves without actually coming in full contact with the lubricant.
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