There are a number of terms and their definitions used in the various articles that are contained here. Additionally, this page serves to marshall many of the other more common terms and acronyms relating to the petroleum industry and to lubricants.
We will be adding to as well as updating when new information comes to light.
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The American Automobile Manufacturers Association (AAMA) is a trade association that represents car manufacturers headquartered in the United States. After the purchase of Chrysler by German Daimler-Benz the organization has been dissolved on December 31, 1998.
The process by ,which one substance draws into itself another substance.
Examples: a sponge picking up water; an oil recovering gasoline from wet natural gas.
Association des Constructeurs Europeens Automobiles (Association of the European Automobile Manufacturers) is the new association of the European automobile manufacturers, formed in February 1991. ACEA is engaged in a broad range of activities including safety and environmental concerns and any regulations which have a direct impact on the European automobile industry. ACEA members are all the European motor vehicle manufacturers including Ford Europe, GM Europe, Scania, and Volvo. At present, only Peugeot is not a member of ACEA but cooperates with ACEA in the field of lubricating oils and fuels.
A member of an important and fundamental category of chemical substances characterized by having an available reactive hydrogen and requiring an alkali to neutralize them. Acid solutions usually have a sour, biting, and tart taste, like vinegar. pH is less than 7.
The residue left after treating petroleum oil with sulfuric acid for the removal of impurities. It is a black, viscous substance containing the spent acid and impurities.
A refining process in which unfinished petroleum products, such as gasoline, kerosene, and lubricating oil stocks, are contacted with sulfuric acid to improve their color, odor, and other properties.
The amount of free acid in any substance.
An agent used for imparting new, or for improving existing characteristics of lubricating oils or greases.
The total percentage of all additives in an oil. (Expressed in % of mass [weight] or % of volume)
The force or forces causing two materials such as a lubricating grease and a metal, to stick together.
American Gear Manufacturers Association
The incorporation of air in the form of bubbles as a dispersed phase in the bulk liquid. Air may be entrained in a liquid through mechanical means and/or by release of dissolved air due to a sudden change in environment. The presence of entrained air is usually readily apparent from the appearance of the liquid (i.e., bubbly, opaque, etc.) while dissolved air can only be determined by analysts.
In chemistry, any substance having basic properties. The term is applied to hydroxides of ammonium, lithium, potassium, and sodium. They are soluble in water; have the power to neutralize acids and form salts. They turn red litmus blue. In a more general sense, the term is also applied to the hydroxides of the so-called alkaline earth metals: barium, calcium, and strontium.
A Journal bearing machine used for determining the load-carrying capacity or Extreme Pressure properties (EP) of gear lubricants.
Temperature of the area or atmosphere around a process, (not the operating temperature of the process itself).
Free of water, especially of crystallization.
The minimum temperature for complete miscibility of equal volumes of aniline and the sample under test ASTM Method D 611. A product of high aniline point will be low in aromatics and naphthenes and, therefore, high in paraffins. Aniline point is often specified for spray oils, cleaning solvents, and thinners, where effectiveness depends upon aromatic content.
In conjunction with API gravity, the aniline point may be used to calculate the net heat of combustion for aviation fuels.
An additive used to control foam.
A fluid, such as ethylene or propylene glycol, which is added to or used to replace the water in the cooling system of engines in order to prevent freezing.
A type of bearing using rollers, cones or balls. They are also known as rolling element bearings.
Resistance to detonation or pinging in spark-ignition engines.
A chemical added to lubricating oils to resist oxidation.
The American Petroleum Institute (API) is a trade association that promotes U.S. petroleum interests, encourages development of petroleum technology, cooperates with the government in matters of national concern, and provides information on the petroleum industry to the government and the public.
Classifications and designations for lubricating oils for automotive engines developed by API in conjunction with SAE and ASTM. An recently also with ILSAC.
Classifications and designations for lubricating oils for automotive transmissions developed by API in conjunction with SAE and ASTM.
A nonscientific and arbitrary scale expressing the gravity or density of liquid petroleum products. The measuring scale is calibrated in terms of degrees API.
The ratio of shear stress to rate of shear of a non-Newtonian fluid such as lubricating grease, or a multi-grade oil, calculated from Poiseuille�s equation and measured in poises. The apparent viscosity changes with changing rates of shear and temperature and must, therefore, be reported as the value at a given shear rate and temperature (ASTM Method D 1092).
Derived from, or characterized by, the presence of the benzene ring.
Association of South-East Asian Nations
The percent by weight of residue left after combustion of an oil sample(ASTM Method D 482).
American Society of Lubrication Engineers. This society is still in existence but is now known as the Society of Tribologists and Lubrication Engineers (STLE). The ASLE had published standards for machine tool lubricants.
Black to dark-brown solid or semisolid cemetitious material which gradually liquefies when heated and in which the predominating constituents are bitumen�s. These occur in the solid or semisolid form in nature; are obtained by refining petroleum; or are combinations with one another or with petroleum or derivatives thereof.
Essentially composed of, or similar to, asphalt; frequently used to describe lubricating oils derived from crude oils which contain asphalt.
The American Society for Testing and Materials (ASTM) is a professional society that is responsible for the publication of test methods and the development of test evaluation techniques.
Technical Committee of the Petroleum Additive Manufacturers
Association Technique de L’lndustrie Europeene des Lubrifiants
- In relation to fuels and combustion in internal combustion engines it is the spontaneous ignition, and the resulting very rapid reaction, of a portion or all of the fuel-air mixture in an engine. The flame speed is many times greater than that which follows normal spark ignition. The noise associated with it is called knock.
- In relation to lubricants it is the temperature at which the lubricant will self ignite when exposed to air and continue to burn.
A unit of liquid measure comprised of 42 U.S. Gallons. Used to measure quantities of crude oil, gasoline and fuel oils.
A base oil is a base stock or blend of base stocks used in an API-licensed engine oil.
Refers to a system that reduces testing costs by permitting the interchangeable use of certain base oils without requiring a full engine test program for each of the base oils.
A base stock is a mineral hydrocarbon or synthetic lubricant component that is produced by a single manufacturer (independent of crude source or manufacturing location), that meets the same manufacturer’s specification, and that is identified by a unique formula, product identification number, or both.
Any quantity of material handled or considered as a “unit” in processing. For example, any sample taken from the same “batch” will have the same properties and/or qualities.
A bench test is a laboratory test that measures various specific performance parameters of an engine oil. Specialized test equipment is used for bench testing.
The mineral montmorillonite, a magnesium-aluminum silicate. Used as a treating agent, also, as a component of drilling mud, and in greases.
Colorless liquid hydrocarbon, C6H6, with one ring of carbon atoms. Made from coal tar and by catalytic reforming of naphthenes, it is used in the manufacture of phenol, styrene, nylon, detergents, aniline, phthalic anhydride, biphenyl, nitrobenzene, chlorbenzene; as a solvent; and as a component of high-octane gasoline.
That portion of the normal pentane insoluble in used lubricating oils which is not soluble in benzene, and which may include the insoluble contaminants from external sources, some matter produced by oxidation and thermal decomposition of the oil, the oil additives, or the fuel. (It is tested by ASTM Method D 893).
The process of mixing lubricants or components for the purpose of obtaining the desired physical and/or chemical properties (see compounding).
Fluorescence; the color of an oil by reflected light which could differ from its color by transmitted light.
The temperature at which a substance boils, or is converted into vapor by bubbles forming within the liquid; it varies with pressure.
The liquid which collects in the bottom of a vessel (tower bottoms, tank bottoms), either during a fractionating process or while in storage.
The state of lubrication when conditions exist that do not permit the formation of a lubricant film capable of completely separating the moving parts. As a result the asperities of the moving parts come in contact and a high wear rate results.
Refined, high viscosity base oils usually made from residual stocks by suitable treatment, such as a combination of solvent extraction, propane asphating or catalytic dewaxing.
The quantity of heat required to raise, by 1°F, the temperature of one pound of water at its maximum density (39.2°F).
The material which collects at the bottom of storage tanks, usually composed of oil, water and foreign matter. Also called Bottoms or Bottom Settling & Watter.
British Technical Council
A gas that is composed of either or both of two isomeric, flammable, gaseous hydrocarbons, C4H10, of the paraffin series: n-butane or isobutane.
Corporate Average Fuel Economy
- The amount of heat required to raise the temperature of 1 gram of water 1ºC, at or near the temperature of maximum density. This unit is called a “small calorie”, or “gram calorie”.
- The amount of heat required to raise the temperature of 1 kg of water 1°C. This unit is called a “large calorie” or “kilogram-calorie”.
A viscometer in which the oil flows through a capillary tube.
California Air Resources Board
Oil (Petroleum), usually solvent neutral (SN) or process oil, used to “carry” or dissolve and/or disperse additives, which would otherwise be too viscous or even solid, and therefore not easily mixed with the Base Stock Oil.
Comite des Constructeurs d’Automobile du Marche Commun
(European Common Market Automobile Manufacturers Association)
European vehicles. This organization was dissolved at the end of 1990. ACEA, the new association of the European automobile manufacturers, formed in February 1991, has decided to retain the CCMC oil sequences and their original designation for a transitional period.
Coordinating European Council
The chief substance composing the cell walls or fibers of all plant tissue, a polymeric carbohydrate with the general formula (C6H10O5)x: it is used in the manufacture of paper, textiles, filters, etc.
The worldwide unit of kinematic viscosity.
- 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.
- A term used in percolation filtration; may be defined as: a preponderance of flow through certain portions of the clay bed.
Commercial Item Description used in many cases in lieu of military specification (MIL).
The temperature at which paraffin wax or other solid substances begin to crystallize or separate from the solution, imparting a cloudy appearance to the oil when chilled (ASTM Method D 97).
Chemical Manufacturers Association is the trade association responsible for the development and administration of the Petroleum Additives Panel Product Approval Code of Practice (CMA Code).
- The undesirable accumulation of carbon (coke) deposits in the internal combustion engine or in a refinery plant.
- The process of distilling a petroleum product to dryness.
- a solid, liquid, or gaseous substance made up of very small, insoluble, nondiffusible particles (as single large molecules or masses of smaller molecules) that remain in suspension in a surrounding solid, liquid, or gaseous medium of different matter
- a state of matter consisting of such a substance dispersed in a surrounding medium All living matter contains colloidal material, and a colloid has only a negligible effect on the freezing point, boiling point, or vapor pressure of the surrounding medium
A factor in the identification, rather than in the quality rating of a petroleum products and lubricants, except where staining or appearance are considerations.
A lubricating grease thickened by a complex soap consisting of a normal soap and a complexing agent.
The addition of fatty oils and similar materials to lubricants to impart special properties. Lubricating oils to which such materials have been added are known as compounded oils.
The gradual eating away of copper surfaces as the result of oxidation or other chemical action. It is caused by acids or other corrosive agents.
The gradual eating away of metallic surfaces as the result of oxidation or other chemical action. It is caused by acids or other corrosive agents or by electro-chemical reaction of the metal with its environment.
A substance which protects a metal against corrosion by substances which originate from products of combustion, or from deterioration of the lubricant.
Lubricant used in the crankcase of the internal combustion engine.
Commissione Tecnica de Unificazione nel l’Autoveicolo
The mass of a unit of volume of a substance as compared to Water which has a density of one.
The ability of an oil to keep working surfaces of equipment clean (i.e. free from contaminants) by holding oil-insoluble material in suspension thus preventing deposition where it would be harmful.
Is a lubricating oil possessing special sludge-dispersing properties usually conferred on the oil by the incorporation of special additives. Detergent oils hold formed sludge particles in suspension and thus promote cleanliness especially in internal-combustion engines. However detergent oils do not contain “detergents” such as those used for cleaning of laundry or dishes. Also detergent oils do not clean already “dirty” engines, but rather keep in suspension the sludge that petroleum oil forms so that the engine remains cleaner for longer period. The formed sludge particles are either filtered out by Oil Filters or drained out when oil is changed.
A measure of the of insulating properties of electrical insulating oils for use in electrical cables, transformers, circuit breakers, and similar apparatus (Tested by ASTM Method D 877).
A synthetic Iubricating fluid made from esters: also called ester oil.
Deutsche Industrie Norm (German Industrial Standards).
A dispersing agent, which holds a very finely divided substance in a dispersed state in the carrier fluid. Such as sludge or a wear particles in a motor oil.
Wide range of and any product produced by distillation.
The process of condensing into liquid the vapours distilled from any liquid such as water, petroleum or alcohol.
In general, the dropping point is the temperature at which the grease passes from a semisolid to a liquid state. This change in state is typical of greases containing conventional soap thickeners. Greases containing thickeners other than conventional soaps may, without change in state, separate oil.
Solid material left between two moving surfaces to prevent metal-to-metal contact, thus reducing friction and wear. Such materials are especially useful in the region of boundary lubrication, and for lubrication under special conditions of extremely high or low temperature where usual lubricants are inadequate. They may be applied in the form of a paste or solid stick, or by spraying, dipping, or brushing in an air-drying carrier which evaporates leaving a dry film. Or can be present in a “sol” a colloidal suspension in Water, Alcohol or Oil. Some examples of dry lubricants are: graphite, molybdenum disulfide, boron nitride, and certain plastics such as tetrafluorethylene resins (PTFE or Teflon).
Energy Conserving (1.5% Fuel Conserving) and Energy Conserving Level II (2.7% Fuel Conserving). It is the ability of lubricant to conserve fuel in gasoline automotive type engines when compared to ASTM HR-2 20W-30 reference motor oil.
Lubrication model modified to take into consideration the elastic properties of the bearing material and the viscosity increase of the lubricant under concentrated load.
The ability of a non-water soluble fluid (such as oil) to form an emulsion with water.
A substance used to promote or aid the emulsification of two liquids and to enhance the stability of the emulsion.
A mechanical mixture of two insoluble liquids such as oil and water.
An engine oil is a lubricating agent that can be classified according to one or a combination of the viscosity grades identified in Table 1 of the most recent edition of SAE Standard J300. Engine oils are also called motor oils. Engine oils include diesel engine oils and passenger car motor oils (PCMOs).
Also called engine sequence test or sequence test, it refers to a test of an oil’s performance using a full-scale engine operating under laboratory conditions.
A measure of viscosity. The ratio of the time of flow of 200 ml of the liquid tested, through the viscometer devised by Engler, to the time required for the flow of the same volume of water gives the number of degrees Engler.
Engine Oil Licensing and Certification System (EOLCS) refers to an administrative process and legally enforceable system by which API authorizes marketers of engine oil to display an API mark or marks on oils that meet specified industry standards, as prescribed in a formal licensing agreement.
Environmental Protection Agency
An Extreme Pressure additive introduced into a lubricant to improve the load-carrying or anti-weld qualities.
Any of the lubricating oils or greases which contain an Extreme Pressure additive specifically introduced to prevent metal-to-metal contact in the operation of highly loaded gears. In some cases, this is accomplished by the additive reacting with the metal to form a protective film.
An animal or vegetable oil which will combine with an alkali to saponify and form a soap.
A grease with a distinctly fibrous structure, which is noticeable when portions of the grease are pulled apart.
Any substance, such as talc, mica, or various powders, which may be added to a grease to make it heavier in weight or consistency, but which serves no useful function in making the grease a better lubricant. (Editor’s note: Starch filler may also be added to certain lubricating oil or other lubricants).
The property of an oil which enables it to maintain an unbroken film on lubricated surfaces under operating conditions, where other otherwise there would be scuffing or scoring of the surfaces.
The lowest temperature at which an oil or other product vaporizes sufficiently rapidly to form above its surface an air-vapor mixture which when subjected to a source of ignition or a flame, will ignite and continue to burn.
Typically for most Petroleum products the Fire Point is about 50°F above the Flash Point.
The lowest temperature at which vapors arising from the oil will ignite momentarily, when subjected to a flame. (i.e., will flash or “poof”).
The vapors will ignite and then go out.
The temperature at which wax or solids separate in an oil.
An agglomeration of gas bubbles separated from each other by a thin liquid film which is observed as a persistent phenomenon on the surface of a liquid.
A substance introduced in a very small proportion to a lubricant or a coolant to prevent the formation of foam due to aeration of the liquid, and to accelerate the dissipation of any foam that may form.
This name is frequently used to describe either of two similar laboratory machines, the Four-Ball Wear Tester and the Four-Ball EP Tester. These machines are used to evaluate a lubricant’s anti-wear qualities, frictional characteristics or load carrying capabilities. It derives its name from the four 1/2 inch steel balls used as test specimens. Three of the balls are held together in a cup filled with lubricant while the fourth ball is rotated against them.
A special case of fretting in which one or more of the surfaces, or the wear particles therefrom, react with their environment. Mechanical wear initiates fretting, then chemical action or “corrosion” results from the exposure of virgin metal surface to the to the air.
- a rubbing, esp. of one object against another.
- Mechanics: The resistance to motion of two moving objects or surfaces that touch.
- Tribology: The resisting force encouraged at the common boundary between two bodies when, under the action of an external force, one body moves or tends to move relative to the other.
A German gear test for evaluating EP properties.
A lubricant composed of a lubricating fluid, thickened with soap or other materiat to a sotid or semisolid consistency.
Oil or other liquid medium used for the transfer of heat.
A number which indicates the ability of an oil to separate from water under conditions specified by the Herschel Demulsibility Test.
A test used to evaluate the rust-preventing properties of metal preservatives under conditions of high humidity (ASTM Method D 1748).
A compound containing only hydrogen and carbon. The simplest hydrocarbons are gases at ordinary temperatures; but with increasing molecular weight, they change to the liquid form and, finally, to the solid state. They form the principal constituents of petroleum.
An oil film which provides a pressure equal to the load. This pressure enables the moving parts to float on a layer of lubricant.
The chemical addition ot hydrogen to a material. In non-destructive hydrogenation, hydrogen is added to a molecule only if, and where, unsaturation with respect to hydrogen exists. In destructive hydrogenation, the operation is carried out under conditions which result in rupture of some of the hydrocarbon chains (cracking); hydrogen is added where the chain breaks have occurred.
Gears in which the pinion axis intersects the plane of the ring gear at a point below the ring-gear axle and above the outer edge of the ring gear, or above the the ring-gear axle and below the outer edge of the ring gear.
A gear lubricant, having extreme pressure characteristics suitable for use with hypoid gears as found, for example, in the differentials of motor vehicles.
The Independent Lubricant Manufacturers Association (lLMA) is a trade association of businesses engaged in compounding, blending, formulating, packaging, marketing, and distributing lubricants.
The International Lubricant Standardization and Approval Committee (ILSAC) is a joint committee of AAMA and JAMA members that assists in the development of new minimum oil performance standards.
A substance in a petroleum product which prevents or retards undesirable chemical changes from taking place in the product, or in the condition of the equipment in which the product is used. Commonly used inhibitors are used to prevent or retard oxidation or corrosion.
International Standards Organization. This organization which is worldwide in scope sets standards and classifications for lubricants. An example is the ISO viscosity grade system.
The Japan Automobile Manufacturers Association (JAMA) is a trade association that represents automobile manufacturers headquartered in Japan.
Japanese Automobile Standards Organization (JASO) is comprised of automobile and truck manufacturers, oil and oil additive companies, and government authorities.
Japanese Industrial Standards
- any substance reducing friction by providing a smooth film as a covering over parts that move against each other; lubricating
- a substance for reducing friction in this way, as oil or grease
[Latin lubricans, prp.: see lubricate]
- to make slippery or smooth
- to apply a lubricant to
- to serve as a lubricant
- slipperiness; smoothness; esp., effectiveness as a lubricant as indicated by this quality
- trickiness; shiftiness
having a strong affinity for, and stabilized by, the liquid dispersing medium: said of a colloidal material. Also lyophile
Having little affinity for the liquid dispersing medium: said of a colloidal material
On December 16, 1992, the Motor Vehicle Manufacturers Association of the United States (MVMA) changed its name to the American Automobile Manufacturers Association (AAMA).
Refers to the marketing organization responsible for the integrity of a brand name and the representation of the branded product in the marketplace.
A unit of linear measure equal to one millionth of a meter, or one thousandth of a millimeter
(Modern Latin < Greek mikron, neut. of mikros, small, minute)
Oil derived from mineral sources, notably petroleum.
A term used to describe an oil when its viscosity falls within the limits specified for a single SAE number.(SAE Standard J300).
A term used to describe an oil for which the viscosity/ temperature characteristics are such that its low temperature and high temperature viscosities fall within the limits of two different SAE numbers. (SAE Standard J300)
One of a group of cyclic hydrocarbons, also termed cycloparaffins or cycloalkanes. The general formula for naphthenes is CnH2n
National Lubricating Grease Institute
One of a series of numbers classifying the consistency range of lubricating greases. The NLGI Numbers are based on the ASTM cone penetration number. The grades are in order of increasing consistency (hardness).
The following table shows the worked penetration values for the various NLGI grades of grease:
||ASTM Worked Penetration*
( NLGI Grease Classifications )
Original Equipment Manufacturer
Passenger Car Motor Oils (PCMOs) refer to engine oils for passenger cars, light-duty trucks, and similar vehicles (see also engine oils).
Consistency of a lubricating grease, expressed as the distance in millimeters that a standard needle or cone penetrates vertically into a sample of the material under known conditions of loading, time and temperature.
The combination, usually under controlled conditions of temperature and pressure in the presence of a catalyst, of two or more unsaturated organic molecules to form a more complex molecule. The products obtained are known as polymers. Typical polymers range from light liquids to rubber like materials.
The products of polymerisation (very large molecules).
The lowest temperature at which oil will pour or flow when it is chilled without disturbance under definite conditions (ASTM Method D 97). It gives an indication of the lowest operating temperature for which particular oil is suitable.
A lubricating oil additive which lowers the pour point of an oil by reducing the tendency of the wax, suspended in the oil, to form crystals or a solid mass in the oil, thus preventing flow.
Also called pour depressor or pour point depressor.
The ability of a pour depressed oil to maintain its original ASTM pour point when subjected to long term storage at low temperature approximating winter conditions.
Oil not used for lubrication, but as a component of another material, or as a carrier of other products, such as additives.
The ability of a lubricating grease to flow under pressure through the line, nozzle and fitting of a grease dispensing system.
Rust & Oxidation inhibited
A Service Category is an alphanumeric code developed by API to specify a level of performance defined by ASTM D 4485 and SAE Standard J183. As new Service Categories are developed, new alphanumeric codes may be assigned.
The Society of Automotive Engineers (SAE) is an engineering society founded to develop, collect, and disseminate knowledge of mobility technology.
A colloidal dispersion in a liquid.
Saybolt Universal Seconds. A measure of lubricating oil viscosity in the oil industry. The measuring apparatus is filled with specific quantity of oil or other fluid and its flow time through standardized orifice is measured in seconds. Fast flowing fluids (low viscosity) will have low value; Slow flowing fluids (high viscosity) will have high value.
- The simultaneous action of separate agencies which, together, have greater total effect than the sum of their individual effects.
- The combined or correlated action of different parts working together.
- In relation to lubricants the beneficial reaction between base oil and additive or between two or more additives.
[Modern Latin synergismus < Greek synergos, working together: see synergy
- combined or cooperative action or force
[Modern Latin synergia < Greek joint work < synergein, to work together < syn-, together + ergon, work]
- of, involving, or using synthesis
- produced by synthesis; specially: produced by chemical synthesis, rather than of natural origin
- not real or genuine; artificial [synthetic lubricant]
- something synthetic; specially, a substance produced by chemical synthesis
- Man-made, not occuring in nature
[French synthétique < Greek synthetikos]
Oils produced by synthesis (chemical reaction) rather than by extraction or refinement. Many (but not all) synthetic oils offer immense advantages in terms of high temperature stability and low temperature fluidity, but are more costly than mineral oils. Major advantage of all synthetic oils their chemical uniformity.
A descriptive term applied to lubricating oils and greases which appear particularly sticky oe adhesive.
The quantity of base, expressed in terms of the equivalent number of milligrams (mg) of Potasium Hydroxide, that is required to titrat the strong acid constituents present in 1 gram (g) of oil sample. (ASTM Method D 644 or D 974).
The quantity of acid, expressed in terms of the equivalent number of milligrams (mg) of Potasium Hydroxide, that is required to titrat the strong base constituents present in 1 gram (g) of oil sample. (ASTM Method D 644 or D 974).
The property of a grease or some gels to decrease in consistency when subjected to a shear stress and return to original consistency when the stress is removed.
One of may laboratory machines used in determining the load carrying ability and capacity of oils and greases. In this test, a Timken Bearing Cup is rotated against a steel block. The highest load under which a lubricant prevents scoring of the steel block by the rotating cup is the reported value.
combining form meaning friction
The study of friction between interacting parts, such as gears, and ways of reducing it.
trib(o) = < Greek tribein, to rub- + -logy = ME -logie < Old French < Latin -logia < Greek < logos, word; also science, doctrine, or theory of
These are derived from a vegetable source. From pure lubrication considerations, they may be regarded as superior to mineral oils as their chemical nature provides excellent adhesion to metal surfaces. However, they have relatively poor high temperature stability and are costly.
An example is castor oil, jojoba oil, sunflower oil, etc..
An arbitrary scale used to show the magnitude of viscosity changes in lubricating oils with changes in temperature. Oils with low VI number such as VI=0 (“zero”) have high dependence of viscosity change on temperature. They thicken quickly with decreasing temperature, and thin out quickly with increasing temperature. Oils with high VI number such as VI=200, will still thicken with decreasing temperature but not as rapidly, and also will thin out with increasing temperature, but again not as much as low VI oil.
VI number can also be “negative”
Tables found in ASTM Method D 2270 are widely used to determine VI number.
However, VI does not tell the whole story — it only reflects the viscosity/temperature relationship between temperatures of 40°C and 100°C. Two lubricants or base oils with the same VI number may perform dramatically different at low temperatures in the -5°C to – 50°C range.
The measure of the internal friction or the resistance to flow a liquid. Low viscosity fluids flow easily (water); High viscosity fluids pour slowly (molasses).
Chemical additive that is added to finished lubricants to improve the viscosity index (see above). While Viscosity Index Improvers can enhance VI, they can break down under shear or over time, resulting in diminished performance.
Possessing viscosity. Frequently used to imply high viscosity.
The degree to which a substance tends to vaporise or evaporate. Liquids with high volatility will loose (by evaporation) high percentage of their weight or volume when heated to specific test temperature (Noack Volatility Test).
The removal of materials from surfaces in relative motion.
- abrasive wear: removal of materials from surfaces in relative motion by cutting or abrasive action of a hard particle (usually a contaminant).
- adhesive wear (scuffing): removal of materials from surfaces in relative motion as a result of surface contact.
- corrosion wear: removal of materials by chemical action.
An additive which protects the rubbing surfaces against wear, particularly from scuffing, if the hydrodynamic film is ruptured.
The penetration of a sample of lubricating grease immediately after it has been brought to 77ºF and then subjected to 60 stokes in a standard grease worker. This procedure and the standard grease worker are described in ASTM Method D 217.
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