Knowledge Centre Knowledge centre ITW Spraytec Expert

Glossary of lubrication

Terminology of certain words? Problem solved!

ABRASIVE WEAR : Wear between two surfaces in relative motion due to particles (3 bodies) or surface roughness (2 bodies)

ABSOLUTE VISCOSITY : A term used interchangeably with dynamic viscosity to distinguish it from kinematic viscosity. The SI unit of absolute viscosity is the pois, but it is usually expressed in centpoises (cP).

ABSORPTION : The process by which one substance attracts another substance into itself, namely water absorbing sponges.

ACCUMULATOR ( HYDRAULIC ) : Device in which hydraulic fluid is stored under pressure in a system used as a fluid source.

ACID : A compound containing hydrogen, which can be replaced by a metal, forming a salt. In the manufacture of fats, fatty acids are used to form a specific type of salt called soap. (See Definition of soap).

ACID AND BASE NUMBER : Indicates the amount of free acidic or alkali materials in a petroleum product. These materials can be inorganic or organic. The acid number is the weight in milligrams of potassium hydroxide ( KOH ) required to neutralize the acidic constituents in one gram of the sample. The base number is the number of milligrams of potassium hydroxide ( KOH ) equivalent to the acid required to react with one gram of the sample. The unit is usually expressed in mg KOH /g. Also known as the neutralization number.

ACIDITY : A valuable indicator of the refining quality of new oil or the extent of oxidation in used oil. Furthermore, as a pH indicator, it reflects the condition of a cutting fluid emulsion affected by excrement, etc., of bacteria suspended in water.

ACTIVATED : The state of a substance that has been specially treated to increase its activity, which may be physical, such as the behavior of catalysts. Organic films and silica are materials that have undergone this type of special treatment when used as thickeners for inorganic grease.

ACTUATOR : A mechanical device, such as a cylinder or hydraulic motor, used to convert hydraulic energy into mechanical energy.

ADDENDUM ( GEARS ) : Distance between the primitive circle and the tip of the tooth.

ADDITIVE : A term used for petroleum oils combined with chemical additives to enhance certain properties such as detergency, antioxidant properties, etc., or any material added to a lubricating grease or oil to improve its suitability for use. It can enhance a property already possessed by the lubricant or impart properties that it does not naturally possess. Typical examples are antioxidants, EP agents, or anti-wear additives.

ADHESION : The force that compels dissimilar substances to stick together, for example, molasses to a spoon. Forces that cause two materials, such as lubricating grease and a metal, to stick together.

ADHESIVE WEAR : Wear caused by metal-on-metal contact; characterized by local welding and surface tearing.

AFFINITY : The attraction between elements which, under favorable conditions, lead to their union.

AGE HARDENING : An undesirable process in which a solid (a grease, an elastomer seal, or a rubber hose) hardens with prolonged storage.

AGGLOMERATION : The potential of the system for the attraction and adhesion of particles.

AGMA : American Gear Manufacturers Association.

AGMA LUBRICANTS NUMBERS : Arbitrary numbers assigned by AGMA to designate different viscosity grades of gear lubricants.

AIR ENGRAVING : The presence of air bubbles in an oil resulting from agitation and/or the release of dissolved air due to a sudden change in the environment. Air entrainment is visible because the oil becomes opaque and bubbles .

AIR DUCT LUBRICATOR : Oil reservoir connected to an air duct which provides automatic air lubrication of air-powered energy-consuming equipment through the action of the venturi .

AIR OIL SEPARATOR : A mechanical device that separates oil, using a centrifugal oil separator, or any other type of oil. Condensation device in an air line.

ALKALI : Any substance having basic properties (as opposed to acidic properties). In a restricted sense in the manufacture of grease, this term applies to the hydroxides of alkali metals, including lithium, sodium, calcium, and other metal ions.

ALKALINITY : Generally speaking, soluble mineral salts based on ammonia or alkali metals are alkalis. The opposite of acidity, as indicated by numbers greater than 7 on the pH scale.

ALUMINUM COMPLEX GREASE : A grease prepared from a lubricating fluid thickened with an aluminum complex soap.

AMORPHIC ( SHAPELESS ) : term applied to materials such as carbon black, as opposed to crystalline materials such as graphite or molybdenum disulfide .

ANGULAR CONTACT BEARING : This antifriction bearing has an inner ring that is inclined at an angle parallel to the shaft axis. In this way, a greater axial load can be applied, in the appropriate direction, in addition to the normal radial load .

ANHYDROUS : To be without water.

ANILINE POINT : The lowest temperature at which equal volumes of aniline and base fuel or hydrocarbon lubricant are completely miscible. A measure of the aromatic content of a hydrocarbon mixture, used to predict the solubility of a base fuel or the cetane number of a distillate fuel.

RING GEARS : Gears that are internal in nature, having parallel teeth similar to spur gears, but cutting on the rim inside or on the inner surface of a cylinder or ring. The associated pinion of a ring gear must, however, be a standard gear.

ANTI – CORROSION ADDITIVE : Helps prevent metal oxidation by displacing water from metal surfaces. It plates onto the metal with a polarizing effect to create an internal “umbrella,” helping to resist the formation of iron oxide.

ANTI – FOAMING AGENT : An additive used to suppress the foaming tendency of petroleum products in use. It may be a silicone oil to break down surface bubbles or a polymer to reduce the number of entrained small bubbles.

ANTI – FRICTION BEARING : A bearing that takes advantage of the benefits of rolling friction over sliding friction. Therefore, the common term “roller bearing” is different from “ball bearing.”

ANTI – MICROBIAL AGENT : A substance that kills or inhibits the growth of microbes, such as bacteria, yeasts, and molds in finished products, such as lubricants.

ANTI – SEAL COMPOUND : A grease-like substance with a significant amount of dispersed lubricant solids, such as graphite powders, molybdenum disulfide, and metallic compounds, primarily used to prevent seizing on threaded joints. Sometimes it is also called a tool sealant compound.

ANTI – WEAR AGENT : Additive or its reaction product, which forms a thin and tenacious film on heavily loaded parts to prevent metal-to-metal contact.

ANTIOXIDANT : Reagents used to prevent oxidation by air or free oxygen of various substances, including greases and gear lubricants.

API : American Petroleum Institute; an organization comprised of producers, refiners, etc. of petroleum and related products. It is dedicated to the study and promotion of all branches of the petroleum industry.

API ENGINE SERVICE CATEGORIES : Quality levels for diesel and gasoline engine oils established jointly by API, SAE and ASTM ; formerly known as API Engine Service Classifications .

API GRAVITY : (See Gravity).

APPARENT VISCOSITY : The ratio of shear stress to shear rate in a non-Newtonian fluid, calculated from the Poiseuille equation and measured in poises or centpoises. The apparent viscosity of most greases varies with shear rate and temperature and should therefore be stated as the value for a given shear rate and temperature.

APPEARANCE : Characteristics of a lubricating grease observable only by visual inspection. This general term includes various characteristics described under BULK APPEARANCE , TEXTURE , BLOOM , COLOUR AND LUSTRE .

AROMATIC : Contains the benzene ring, as in the asphaltic residues from crude mineral oil distillation. An undesirable component of crude oils that must be removed during the refining process to improve oxidation resistance and viscosity index.

ASHES : Metallic deposits formed in the combustion chamber and other engine parts during high-temperature operation.

ASH CONTENT : A measure of the amount of inorganic matter in lubricating oil. Determined by burning the oil and weighing the residue.

ASPERITIES : Microscopic projections on metal surfaces resulting from normal surface finishing processes. Interference between opposing asperities in sliding or rolling applications is a source of friction and can lead to welding and spalling of the metals. Ideally, the lubricating film between two moving surfaces should be thicker than the combined height of the opposing asperities.

ASPHALT / BITUMEN : Also called asphalt or tar, bitumen is the viscous brown or black residue from the vacuum distillation of crude oil. It also occurs naturally in the form of asphalt “lakes” and “tar sands.” It consists of high molecular weight hydrocarbons and minor amounts of sulfur and nitrogen compounds.

ASTM : American Society for Testing and Materials; an agency that standards testing for petroleum products.

AUTO – IGNITION POINT : The point at which a material spontaneously ignites without the presence of a flame. (See Flash Point).

AXIAL : The line around which a body rotates, i.e., the axis of a bearing/shaft. A bearing supporting axial loads is called a thrust bearing.

AUTOMATIC TRANSMISSION FLUID ( ATM ) : Fluid for automatic transmissions in motor vehicles.

BACTERIA : The smallest units of life capable of independently performing all the basic functions of life.

BACTERIAL DEGRADATION : The effect of excessive bacterial action is to increase the acidity of a cutting fluid emulsion and deplete the emulsifiers to the point of compromising corrosion protection. Ultimately, the emulsion can no longer be maintained and separates into layers of its constituents.

BACTERICIDE : Additive to inhibit bacterial growth in the aqueous component of fluids, preventing foul odors.

BARIUM COMPLEX GREASE / BARIUM : A grease prepared from a lubricating fluid, thickened with barium soap or barium complex soap.

BASE OIL (Base Stock) : Commonly used to refer to the oily phase of a grease, these terms apply more correctly to refined oil before blending or before additions are made to improve performance.

BASE STOCK : The base fluid, usually a refined petroleum fraction or selected synthetic material, into which additives are blended to produce finished lubricants.

BASES : Compounds that react with acids to form salts plus water. Alkalis are water-soluble bases used in petroleum refining to remove acidic impurities. Lubricating oil additives incorporate oil-soluble bases to neutralize acids formed during fuel combustion or lubricant oxidation.

BEARINGS : Contact surfaces between a machine frame and moving parts, providing support and guidance to sliding, rotating, or semi-rotating elements. However, these are not necessarily stationary parts, as in the case of stud and crank bearings, where both the bearings and spindles are in motion. Another type of bearing uses rolling elements such as balls or rollers to control the relative movements of connected parts; these are known as antifriction bearings.

BENCH TEST : Modified service test in which service conditions are approximated in the laboratory.

Thickened Bentonite Greases : A non-soap thickened grease that uses a powdered clay mineral to absorb the base oil, without the need for chemical reactions or shearing. They have a wide operating temperature range and very good water resistance. They are said to have no drop point.

BENZENE : Aromatic hydrocarbon used as an intermediate and as a solvent. Benzene is a toxic substance.

BETA RATING : A method for comparing filter performance based on efficiency. This is done using a multi-pass test that counts the number of particles of a given size before and after the fluid passes through a filter.

BETA – RATIO (Ο- RATIO ) : Ratio between the number of particles greater than a given size in the incoming fluid and the number of particles greater than the same size in the effluent fluid, under specified test conditions.

BEVEL GEAR : A gear in which the teeth are cut on an angular surface, as would be the case with a truncated cone. They are used for transmitting motion between shafts whose intersecting center lines form an angle with each other, usually at 90 degrees.

BIODEGRADABLE : Capable of decomposing under the action of living organisms.

BIODEGRADABILITY : Measurement of the degree to which a lubricant is converted into harmless substances in waterways, forests, etc. by the action of microorganisms such as bacteria and protozoa.

BIODEGRADATION : The process of chemical decomposition or transformation of a substance caused by living organisms and their enzymes.

BLACK OILS : Lubricants containing asphaltic materials, which provide additional adhesion, which are used for open gears and steel cables.

OIL ( GREASE ) PURGE / SEPARATION : Separation of oil from a grease structure. A certain amount of bleeding is considered desirable in greases, as this tends to ensure continuous oil lubrication to the bearings.

MIXTURE : Mixture is considered the process of combining lubricating components to achieve the desired physical and/or chemical properties. The intention is to distinguish between a mixture and a composition.

COMPOSEING : Considered as the mixing or combination of lubricating components with other components for the purpose of securing chemical and/or physical properties that cannot normally be obtained by mixing fluid lubricating components.

BLOCK GREASE : A less common grease with a very hard consistency (at least NLGI No. 5). Often used in the textile industry where shafts are placed in ball bearings and the block of grease is kept in contact with the shaft; the friction would then soften the grease to provide lubrication to the bearing.

BLOOM : The surface color (usually blue or green) of a lubricating oil or grease as seen in daylight reflected at an angle of approximately 45 degrees to the surface. BLOOM is associated with the absorption of ultraviolet light in the oil and may not be visible if the sample is viewed under artificial light. Also called “Fluorescence” or sometimes “Outertone”.

BLOW -BY : Unburned gas and fuel that bypass the compression rings and go to the engine crankcase every time the engine starts.

BODY : Refers to consistency or viscosity. Heavy or high body is synonymous with high viscosity.

OXIDATION STABILITY ‘ BOMB ‘ : Test method used to measure the oxidation stability of greases and lubricating oils .

BOUNDARY LAYER : The layer of nearly stationary fluid that lies immediately adjacent to the surface of a solid, beyond which the fluid flows with minimal effect. This description applies more to hydraulics and aerodynamics than to common lubrication usage—here, it means “the area immediately adjacent to a lubricated surface where full-flow or thick-film lubrication does not properly separate the wear surfaces.” (See Asperities, Friction, Thin-film lubrication, Solid lubrication, Wear).

BORDER LUBRICATION : Lubrication between two friction surfaces without the development of a complete fluid lubricant film. It occurs under high loads and requires the use of anti-wear or Extreme-Pressure (EP) additives to prevent metal-to-metal contact.

RESPIR : An air filter placed on top of a tank allows it to “breathe” as the oil level rises and falls. All incoming air is filtered to prevent contaminants from entering the air.

BRIGHT STOCK : A heavy residual lubricant stock with a low pour point, used in finished mixtures to provide good bearing film strength, prevent scuffing, and reduce oil consumption. Usually identified by its viscosity, SUS at 210°F or cSt at 100°C.

BRINELLING : Damage caused by the impact of one load-bearing component against another while stationary.

BROMINE NUMBER ( VALUE ) : The percentage of bromine that will be absorbed by a chemically unsaturated substance (base oil, vegetable oil, rubber, etc.) at a given time under arbitrary conditions. A measure of unsaturation.

BROOKFIELD VISCOSITY : Measurement of apparent viscosity as determined by the Brookfield viscometer at a controlled temperature and shear rate.

BULK APPEARANCE ( GREASE ) : The visual appearance of grease when the undisturbed surface is viewed as an opaque container. BULK APPEARANCE should be described in the following terms:

CALCIUM COMPLEX GREASE / CALCIUM : A grease composed of a lubricating fluid thickened with calcium soap or calcium complex soap.

CALCIUM ( LIME ) GREASES : Metallic soap greases which have a particular resistance to water.

CALCIUM SULFONATE COMPLEX FAT : Calcium – neutralized fat thickened with sulfonic acid and other acids.

CAMS : Eccentric shafts used in most internal combustion engines to open and close valves.

CAPILLARITY : The tendency of certain liquids to rise through capillary tubes or narrow orifices. This property is important in wick lubricators, kerosene lamps, etc.

CARBON DIOXIDE (CO2) : A colorless, odorless gas produced by the complete combustion of an air-hydrocarbon mixture. A harmless component of the exhaust from an internal combustion engine.

CARBONIZATION : Creation of unwanted, non-lubricating carbon debris and residues ranging from gums and varnishes to abrasive coking. Caused by high temperature and subsequent oxidation of the lubricant.

CARBON MONOXIDE (CO) : A colorless and highly toxic gas produced by the combustion of organic compounds with a limited amount of oxygen. A component of vehicle exhaust emissions.

CARBON RESIDUES : Coked material remaining after an oil is exposed to elevated temperatures under controlled conditions. A laboratory test originally developed to compare the carbon-forming properties of lubricating oils used in internal combustion engines, but now with more general applications.

CATALYST : A material that promotes a chemical action without itself participating in the reaction.

CATALYTIC CONVERTER : An integral part of vehicle emission control systems since 1975. Oxidizing converters remove hydrocarbons and carbon monoxide (CO) from exhaust gases, while converters controlling nitrogen oxide (NOx) emissions reduce emissions. Both use catalysts based on noble metals (platinum, palladium, or rhodium) which can be poisoned by lead or phosphorus compounds in the fuel or lubricant.

CATASTROPHIC BREAKDOWN : Unexpected failure of a machine that results in considerable costs and downtime.

CAVITATION : The formation and subsequent collapse of vapor cavities in a liquid; caused by movement or vibration in the liquid film. In a lubricating grease distribution system, any failure of material in the system pump intake (for any reason) (see also Supply Capacity).

CAVITARY DAMAGE : Erosion process in which metal is removed by cavitation.

CENTIPOISE (cP) : A centpoise is 1/100th of the unit of absolute viscosity (the pea). For example, the viscosity of water at 20°C is approximately one centpoise. The centpoise is derived from a kinematic unit of viscosity (the centistoke) by multiplying it by the density of the liquid, i.e., 1 centpoise = 1 centistoke x the density of the liquid.

CENTISTOKE (cSt) : Unit of measurement for the kinematic viscosity of a fluid. One centistoke is equal to 0.01 Stokes and is equivalent to 1 mm²/s in SI units. (See the definition of Stoke).

CENTRALIZED LUBRICATION : A lubrication system in which lubricant intended for various parts of a machine or group of machines is supplied from a central location.

CETANE RATE : Value calculated from the physical properties of a diesel fuel in order to predict its cetane rate.

Cetane Number : A measure of the ignition quality of a diesel fuel, determined by a standard single-cylinder test engine, which measures ignition time relative to major reference fuels. The higher the cetane number, the faster the direct-injection engine starts and the less “white smoke” and “diesel knock” there will be after starting.

CETANE NUMBER ENHANCEMENT : An additive (usually an organic nitrate) that increases the cetane number of a fuel .

CHAIN ​​LUBRICATION : The links, plates, and pins of a chain experience sliding friction , requiring lubricant to minimize wear. Oils used for chain lubrication must have penetrating and adhesive properties, in addition to additives for operational performance.

CHANNELING : A term used in relation to lubricating greases to describe the (usually desirable) tendency for a bearing to channel through the removal of lubricating grease, leaving shoulders of unworked grease that act as a seal and reservoir. A term used in relation to liquid lubricants and flow-type lubricating greases to describe the tendency, at low temperatures, to form a plastic structure strong enough to resist flow only under the influence of gravity. (Similar to, but not identical to, the pour point of liquid lubricants, it is measured by empirical tests such as Federal Test Method 791C 3456-2.)

CHLORIDE : In lubricants, this refers to the inclusion of chlorinated compounds as extreme pressure (EP) additives. The term also encompasses any chemical combination of chlorine or its compounds with another group, for example, on hydrocarbon chains.

HEATING : Constant shearing (work) of grease in a bearing leads to overheating, resulting in a significant loss of consistency, which perpetuates itself until the extremely fluid grease flows out of the bearing. The most likely causes are overfilling and selecting a grease that is too thin for the application. (See Channeling, NLGI , Penetration, Slumping).

OIL SYSTEM CIRCULATION : In such lubrication systems , oil can be pumped directly under pressure to the parts to be lubricated , or, in a gravity-fed system, the oil is pumped into a reservoir located above the parts to be lubricated and flows out by gravity. The used oil then flows into a sump from which it is pumped through a filter or centrifuge, and then, usually through an oil cooler, back into the original reservoir. The term is also sometimes used to describe the pressure lubrication system of automotive engines.

CLAY THICKENER : Term used in reference to bentonite.

CLEANLINESS CLASSIFICATION : A classification based on the number of particles of specified sizes in a fluid measurement. ISO 4406 specifies the code to be used for this classification.

CLOUD POINT : The temperature at which a cloud of wax crystals appears when a distillate lubricant or fuel is cooled under normal conditions. Indicates the material’s tendency to clog filters or small orifices in cold weather.

COEFFICIENT OF FRICTION : The ratio of friction between two surfaces to the pressure between them. A low coefficient of friction means low friction losses, influenced by the viscosity and characteristics of the lubricant, the materials, surface conditions, and other factors.

COHESION : Molecular attraction causes the particles of a given substance to attract and stick together. Cohesion contributes to the resistance to flow of a lubricating grease.

COLD START SIMULATOR ( CCS ) : Intermediate shear rate viscometer that predicts an oil’s ability to allow the development of a satisfactory starting speed in a cold engine .

COLLOID : Substances whose particle size is larger than that of their molecules, but small enough to possess reasonable dispersion stability in two-phase systems. A lubricating grease is a colloidal system (see also thickening agent).

COLOR ( LUBRICANT ) : The shade and intensity shown when the lubricating grease is viewed under conditions such as bloom removal . These conditions can be achieved by observing the lubricating grease in an opaque container, such as a metal case, in reflected light, from a position approximately perpendicular to the surface; or by viewing it with transmitted light only, by placing the sample on a transparent plate. When lubricating grease colors are mentioned, the method of color determination should be clearly stated. Lubricating grease colors are best described in terms of the predominant hue, such as amber, brown (or perhaps green, red, or blue), with a qualifying adjective describing the intensity in terms of light, medium, or dark (of the lubricating oil). This shade is visible only under transmitted light. Lubricating oil colors are typically obtained by examining the oil under the conditions specified in the test equipment. Several methods of this type are available, the most widespread being ASTM D1500, which describes colors by number.

SOAP COMPLEX ( GREASE ) : A soap used to thicken the grease in which the soap crystal of the fiber is formed by the co-crystallization of two or more compounds: Normal soap (such as metallic stearate). The complexing agent. Examples of complexing agents are metallic salts of short-chain organic acids, such as acetic or sebacic acid, or inorganic salts such as carbonate or borate.

COMPOSITION : Considered as the mixture or combination of lubricating components with other components for the purpose of securing chemical and/or physical properties which are not normally obtained by mixing fluid lubricating components.

COMPOUND OIL : Mineral oil to which vegetable or animal oil or chemical additives of lubricating oils have been added in order to improve certain physical or chemical properties of the finished mixture.

COMPRESSION RATIO : In an internal combustion engine, the ratio between the volume of the combustion chamber at bottom dead center and at top dead center.

CONDITION MONITORING : The use of specialized techniques to monitor the condition of equipment and detect the onset of failure early enough to allow for planning maintenance interventions to prevent failures. These techniques include lubricant analysis, vibration analysis, thermography, current signature analysis, non-destructive testing ( NDT ) , and surface inspections (such as ultrasonics, acoustic emission, electromagnetic fields, radiography, magnetic particle testing, and dye penetrant testing).

CONSISTENCY / HARDNESS ( GREASE ) : The extent to which a plastic material, such as lubricating grease, resists deformation under force. (This is therefore a characteristic of plasticity, as viscosity is a characteristic of fluidity. Consistency is usually indicated by apparent viscosity or the NLGI grade .)

CONTAMINATION : Pollution of a lubricant by an external agent.

COPPER CORROSION TEST : To determine whether a lubricant contains corrosive substances, a polished copper strip is immersed in the lubricant, which is then maintained at a high temperature for several hours. If the lubricant contains even the slightest trace of a chemically reactive substance under these conditions, the copper strip will discolor, leaving a characteristic dark film. This test is particularly useful for detecting the presence of corrosive sulfur compounds.

CORROSION : Any chemical reaction that results in the conversion of useful materials, usually metals or alloys, into substances worthless for the purposes for which the original material served its purpose. Rust is the most common example of corrosion, a chemical attack or reaction on metals caused by an acid, alkali, chlorine, sulfur, or other chemicals. This is distinct from the destruction of metal by wear and may be evident as discoloration or pitting.

CORROSION INHIBITOR : Additive that protects lubricated metal surfaces from chemical attack by water or other contaminants .

CORROSIVE WEAR : wear caused by a chemical reaction.

COUPLING : A frequently used alternative term for a fitting: a straight connector for fluid lines; or a large diameter device that joins the ends of two shafts, between a motor shaft and a gear drive unit, for example.

CROWN : The upper part of the piston in an internal combustion engine located above the firing ring, exposed to direct contact with the flames.

GREASE TUB : Common name for lime soap grease. It is generally a calcium-based grease, yellowish in color and with a buttery texture, intended for use in grease pots.

CUTTING FLUID /OIL : Oil used in machining operations to lubricate the cutting tool, to dissipate heat generated by friction and stress on the metal, and to prevent rust and corrosion of the machine tool or workpiece.

DEEP – COVERED BALL BEARING : Probably the simplest type of anti-friction bearing. Because the balls roll in a deep raceway, they are able to support a certain axial load in addition to the larger radial load vector. This type of bearing is capable of high speeds and is easy to lubricate .

DEMULSIBILITY : A measure of a fluid’s ability to separate from water.

DENATURANTS : Toxic or harmful components used in fuel ethanol to render it unfit for consumption.

DENSITY : mass per unit volume. Generally, the unit is expressed in g/ml, g/L or kg/m3.

DEPOSITS : Materials insoluble in oil resulting from the oxidation of the oil and contamination by external sources (combustion products in the internal combustion engine) and which are deposited on the parts of the machine or engine in the form of sludge or varnish.

DETERGENCY : Cleaning, purging. Property of an oil that prevents the deposition of gums or lacquers on engine parts and to which carbon from the combustion chamber would otherwise adhere.

DETERGENT : A substance added to fuel or lubricant to keep engine parts clean. In engine oil formulations, the most commonly used detergents are metallic soaps with a reserve of alkalinity to neutralize acids formed during combustion.

DETERGENT / DISPERSANT : An additive that combines a detergent and a dispersant.

DETONATION : Uncontrolled burning of the last part (end gas) of the air/fuel mixture in the cylinder of a spark-ignition engine. Also known as “knocking” or “pinging”.

DIELECTRIC STRENGTH : a test designed to measure the insulating properties of oils, carried out by applying increasing voltage to the oil under specified conditions until rupture, marked by the establishment of an arc.

SOLVENT- BASED THINNER / FLUIDIFIER : Instead of heating, a solvent is added to viscous lubricants to allow application in cold weather. The solvent evaporates after application, leaving the lubricant in place. Thinners are widely used in lubricants for open gears.

ENGINE OIL DILUTION : Contamination of the crankcase oil by unburned fuel, resulting in reduced viscosity and flash point. May indicate worn components or improper fuel system tuning.

DILUTION RATIO : The relative proportions of concentrate to water in a cutting fluid emulsion .

DISPENSABILITY : A property of a grease that determines how easily it can be transferred from its container to its point of application. It is most commonly used in discussions about grease distribution systems, where it encompasses both pumpability and feedability.

Dispersant : An additive that helps keep solid contaminants in crankcase oil in colloidal suspension, thus preventing sludge and varnish deposits on engine parts. Generally non-metallic (“ashless”) and used in combination with detergents.

DISPERSING ACTION : Property of an oil that prevents the coagulation or sticking of carbon particles by keeping them in a finely divided state, and which thus prevents their deposition and deposition on engine parts.

DISPERSION : A suspension of tiny, discrete particles in a liquid, gas, or solid. The particle size of a dispersion differs primarily from that of a colloid: the dispersion is not homogeneous, and the particles eventually settle.

DISTILLATION : Basic test used to characterize the volatility of a distilled gasoline or fuel.

DN (DmN) FACTOR / SPEED FACTOR : used as a guide for lubricant selection for rolling contact bearings. The DN value is determined by the average bearing diameter in mm (D) multiplied by the bearing speed under standard operating conditions in rpm (N).

DOUBLE – ROW BEARING : An anti-friction bearing capable of supporting much higher loads than a single double-row bearing. The ball or roller ring and cage are duplicated in a single bearing.

DOWNTIME : Machine time lost due to mechanical failure. Also refers to downtime for servicing or maintenance.

DROP POINT ( GREASE ) : The temperature at which a drop of material falls from the orifice of the test apparatus under the conditions of ASTM D566 or D2265 tests. This test should be considered as having very limited impact on service performance. It is not the melting point of the grease; this is a term of little or no importance when applied to plastics such as lubricating grease. These materials are characterized by a melting range during which they become progressively softer. Only by implementing an arbitrary and fully controlled test procedure such as the ASTM standard can the drop point, a single temperature, be established as a characteristic of the material. This test, performed on a grease, generally indicates the transition temperature from the solid or semi-solid to the liquid state.

DRY FILM LUBRICANT : A solid material, such as graphite, molybdenum disulfide, or PTFE , used with fillers in the lubricating boundary zone. These materials can be applied as pastes, by spraying, dipping, brushing into an air-drying substrate, burnishing , or resin bonding.

DYNAMIC VISCOSITY : A measure of the resistance to flow in a fluid. Dynamic viscosity is also called absolute viscosity. (See Absolute Viscosity).

Elastohydrodynamic LUBRICATION ( EHD ) : A lubricant regime characterized by high unit loads and high speeds in rolling elements in which the coupling elements deform elastically due to the incompressibility of the lubricant film under very high pressure.

ELASTOMER : A natural or synthetic material of rubber or similar to rubber, which can be repeatedly stretched and returns to its approximate original dimensions when the stress is released.

EMCOR : Test method used to evaluate the corrosion resistance of a grease in a bearing.

FAT EMULSIFICATION : coarse contamination of a fat with water resulting in a loss of consistency and a “dilution” of all properties .

EMULSIFIER : An additive that promotes the formation of a stable mixture, or emulsion, of oil and water.

EMULSION : A mixture of water and oil in which very small water droplets are suspended in oil, or similar oil droplets are suspended in water, all stabilized by a third component such as soap, called an emulsifier. Milk is an emulsion of fat in water. A liquid in which another immiscible liquid is suspended. Water and oil can be emulsified under certain conditions of oil type and vigorous stirring. Emulsifying agents are sometimes added to oils for the production of cutting fluids to be mixed with water.

END POINT : The highest vapor temperature recorded during a distillation test of a stock of oil.

ENGINE DEPOSITS : Hard or persistent accumulation of sludge, varnish, lacquer , and carbon residues due to the exhaust of unburned and partially burned fuel, or partial degradation of the crankcase lubricant. Water from the condensation of combustion products, carbon, fuel additive or lubricating oil residues, dust, and metallic particles also contribute.

EP AGENT ( EXTREME PRESSURE ADDITIVE ) : Lubricating additive that prevents seizing of sliding metal surfaces under extreme pressure conditions .

EROSION : wear of a surface by a colliding fluid or solid.

ESTERS : Compounds formed by the combination of an organic acid and an alcohol. An ester compound, such as a diester or polyol ester, is widely used as a type of synthetic oil.

EVAPORATION LOSS : The portion of a lubricant that evaporates due to temperature, pressure, and time. Such loss can occur during use or storage. The widely used test method is ASTM D972 .

FALEX TEST : Used to determine the extreme pressure (EP) or anti-wear properties of oils and greases. V-shaped blocks are placed on opposite sides of a rotating steel shaft, and the apparatus is immersed in a test lubricant bath. The load is automatically increased until it reaches a set point. Measurable wear marks are formed on the blocks.

FALSE BRINELLING : rubbing of one load-bearing component against another; may appear as a dent, but the original surface finish is worn.

FAT : An animal or vegetable oil that combines with an alkali to saponify and form soap (see Definition of soap).

FATIGUE : Cracking, chipping or bursting of a surface due to stresses exceeding the material’s endurance limit.

FATTY ACID : The part of the fat that reacts to acid. Fatty acids are more uniform because refining the fat produces a more uniform raw material.

FAT ESTERS : Used as fatty additives in the boundary layer of lubricants and to promote a good surface finish. (See Esters).

FEEDING : The ability of a lubricating grease to flow towards the suction of a distribution pump at a rate at least equal to the pump’s capacity. (Some lubricating greases do not feed satisfactorily and cause cavitation at the inlet of a distribution pump).

FERROGRAPHY : Analysis of magnetic particles.

FIBER : In lubricating greases, soap fibers form thickeners, crystallizing into threads that are 20 times or more in diameter, as long as they are thick. (Most soap fibers are microscopic in size, so the grease appears smooth to the naked eye. Greases with a fibrous appearance are those where the fiber bundles are large enough to be seen with the naked eye. The most common fibrous lubricating grease is sodium-based, although not all sodium-based greases are fibrous.)

FIBRIL : An extremely small fiber, usually barely visible even at maximum magnification with an electron microscope. Fibrils can bundle together to form larger fibers.

FIELD TESTING : After development and laboratory testing, it is necessary to ensure practical performance in various applications and to assess market acceptance.

FILM STRENGTH : The ability of a film or lubricant to resist rupture due to load, speed, and temperature .

FLASH POINT / FIRE POINT : The minimum temperature at which a fluid will ignite instantaneously (a flash), but before burning continuously (fire point). The flash point is an important indicator of the fire and explosion hazards associated with a petroleum product.

FLUID FRICTION : Internal friction of the lubricating oil film occurs when solid surfaces between which relative motion takes place are completely separated by a fluid film. Under such conditions, the oil flows in parallel layers, like a deck of cards sliding over one another when the outer cards adhere to the palms of the hands and the palms move relative to each other, causing the outer cards to move, with the hands and the middle cards also moving relative to their position in the deck.

LIQUID GREASE : A term used to describe a grease of very soft consistency. NLGI penetration levelless than ‘I’. A grease used in centralized lubrication systems, where the grease must flow, under pressure, through long hoses to a bearing. In certain circumstances, fluid greases may be used in gearboxes.

FLUIDITY : The property of flowing freely: the opposite of viscosity.

FOAMING : Foaming in oil is usually caused by excessive agitation, moisture contamination, or air penetration into suction lines.

TRACKING PLATE : A piece of sheet metal used above the grease in a pump-type dispenser to ensure the grease remains level during pumping. This prevents a cavity from forming around the grease pump’s pickup tube and allows all the grease to be dispensed into the container without the need for manual top-ups.

Food and Drug Administration ( FDA ) : An agency administered by the U.S. Department of Health and Human Services to enforce the Federal Food, Drug , and Cosmetic Act and thereby ensure that food is safe, pure, and wholesome, and that drugs and therapeutic devices are safe and effective for their intended uses; that cosmetic products are safe and made from appropriate ingredients; and that all such products are labeled and packaged honestly and informatively. (Note: The FDA does not approve products. See NSF .)

FOOD- GRADE LUBRICANTS : Oils and fats that may come into contact with food. National governments, food manufacturers, and consumers require that these products be assessed for toxicity.

FOUR – BALL METHOD : In this popular test method, developed for Shell Oil Co., three steel balls are clamped together to form a cradle on which a fourth ball rotates on a vertical axis. The three clamped balls are immersed in the lubricant under test and loaded against the rotating fourth ball. The four-ball wear method is used to determine the anti-wear properties of lubricants operating under boundary lubrication conditions by measuring the wear scars developed on the balls during the test. The four-ball EP method is designed to evaluate performance under much higher loads, where the risk of lubrication film breakdown is increased, resulting in scoring and welding (see Load-Wear Index).

FRET : A form of wear resulting from oscillating or vibratory motion of limited amplitude, leading to the removal of very finely divided particles from floating surfaces. In the case of ferrous metals in air, the wear particles oxidize into a reddish, abrasive iron oxide, which has given rise to the name FRET CORROSION . This latter phenomenon has also been called FAUX brinelling AND FRICTION OXIDATION when it has occurred in rolling bearings.

FRICTION : Resistance to movement between two surfaces in contact. When two surfaces are brought into contact and are made to slide against each other, a force immediately comes into play and resists this movement. This force is called friction. Friction is not limited to solids; it plays an equally important role with liquids and gases.

FROST : Field of micropitches; form of micro-adhesive wear.

Fungus (plural, fungi) : The simplest microorganism with a true cell wall. They appear as unicellular yeasts (several times the size of bacteria) or filamentous molds. These filaments grow and deposit spores that form new colonies in a “mat” that can eventually clog the cooling pipes, etc., of machine tools. (See Fungicide).

FUNGICIDE : A chemical product that kills fungi preferentially or selectively.

FZG FOUR – SQUARE SPEED OIL TEST (Research Center for Gears and Gear Building) : This test is used in the development of industrial gear lubricants to meet equipment manufacturer specifications. The FZG test equipment consists of two gear trains arranged in a four-square configuration , driven by an electric motor. The test train is subjected to progressively increasing load levels until failure, which is defined as the point at which a weight loss of 10 milligrams per gear train is recorded. Also known as the Niemann four-square gear oil test.

GALLING : When loads are heavy and the film strength in the oil is insufficient to support the load, momentary metal-to-metal contact occurs, producing a ridge at the pitch line of the driven gear and a gullet at the starting line of the driving gear. In severe cases, metal wear occurs along the faces and flanks of the gear teeth, also known as “scaling”.

GAS : The vapor state of any substance having neither independent form nor volume.

GAS FUELS : Liquefied or compressed hydrocarbon gases (propane, butane or natural gas), which are increasingly used in motor vehicles to replace gasoline and diesel fuel.

GASOLINE : Volatile mixture of liquid hydrocarbons containing small amounts of additives and which can be used as fuel in spark-ignition internal combustion engines.

GASOLINE / ETHANOL MIXTURE : Fuel for spark-ignition car engines containing denatured ethanol in a base gasoline. It can be leaded or unleaded.

GEAR LUBRICATION : Gears, whether closed or open, require lubricants that resist film degradation under high pressure and often significant sliding friction. Many gear lubricants contain extreme pressure (EP) additives and tend to use high-viscosity mineral or synthetic oils. Lubricants for open gears will be extremely adhesive and will contain adhesion-enhancing additives.

SPEED RATIO : Ratio of the number of teeth of the pinion to the number of teeth of the pinion, as well as of the number of teeth of the worm gear to the number of teeth of the worm.

GEL : Elastic solid mixture composed of a colloid and a liquid possessing an elastic limit and a gelatinous texture.

GEL GRASSES : Inorganic thickeners are used in gelled greases to absorb lubricating oil. (See Bentonite, Silica, Thickener).

GENERAL PURPOSE GREASE : Also, incorrectly, called “multi – purpose grease.” While a multi-purpose grease claims to be successful in many applications and situations, a general purpose grease makes no particular claim; it is only suitable for non-extreme conditions.

GLYCERIDES : Ester of glycerol and fatty acids.

Graphite : A soft form of elemental carbon, gray to black in color. It occurs naturally or is synthesized from coal or other carbon sources. It is used in the manufacture of paints, pencils, crucibles, and electrodes. It is also widely used as a lubricant, alone or in combination with conventional lubricants, to provide anti-wear properties.

GRAVITY : Given in two forms, either API gravity or density. The first is an arbitrary standard adopted by the American Petroleum Institute (the higher the number, the lighter the oil). Density is the ratio between the weight of the oil and the weight of equal volumes of water.

GREASE : A solid to semi-fluid product resulting from the dispersion of a thickening agent in a liquid lubricant. Other ingredients that impart special properties may be included.

GUM : See varnish.

HALOGENATE SOLVENT : A solvent formulated with one of the halogens, usually chlorine or fluorine. Most halogenated solvents are associated with atmospheric ozone depletion.

HEAT : energy released during combustion.

HEATING VALUE : A measure of the amount of energy available in a fuel to produce work, expressed in Btu/lb or Btu/gal.

HELICAL GEAR : Similar to spur gears in that the teeth are cut on a cylindrical body, but differs in that the teeth spiral around the body rather than being formed parallel to the axis of the gear body. The spiral of the teeth provides smooth operation.

HERRINGBONE GEAR : Resembles two helical gears with opposite spiral directions, placed side by side so that the teeth interlock to form a herringbone pattern. In the herringbone gear, the rotation of the teeth in both directions neutralizes the final thrust.

HERTZIAN : In elasto-hydrodynamic lubrication ( EHD ), a term used to describe surface deformations resulting from extreme load pressures. The Hertz curve, used in the four-ball test for wear resistance index calculations, is based on a formula that determines the contact area between two spherical surfaces caused solely by their deformation under load.

HIGH TEMPERATURE HIGH SHEAR RATE VISCOSITY ( HTHS ) : A measure of a fluid’s resistance to flow under conditions that resemble heavily loaded plain bearings in combustion engines, typically 1 million S-1 at 150°C.

HOMOGENIZATION : A process of subjecting a lubricating grease to intimate mixing and intense shearing, resulting in a higher and more uniform degree of dispersion.

HOMOGENIZER : The machine used in grease manufacturing to ensure effective homogenization.

HYDRATED SOAP : A soap that has water associated with its structure. A typical example is water-stabilized calcium soap grease, which owes its stability to the hydrated calcium soap.

HYDRAULIC FLUID : Hydraulic fluids are used to transmit force from one part of a system to another, as in hydraulic brakes, to dampen forces applied suddenly, as in shock absorbers, or to slow movement, as in gun recoil mechanisms.

HYDROCARBONS : Compounds containing only carbon and hydrogen. Petroleum consists primarily of hydrocarbons.

HYDROCARBON POLYER : A repeating chain of hydrocarbon molecules. (See polymer).

LUBRICATION : This state of lubrication is characterized by the shape and relative movement of sliding surfaces, resulting in the formation of a continuous fluid film under sufficient pressure to prevent any contact between the surfaces. It is also called fluid film lubrication.

HYDROFINISHING : Process of treating extracted bases with hydrogen to saturate them and improve their stability.

HYDROLYSIS : Decomposition of a chemical compound following a reaction with water.

HYDROLYTIC STABILITY : The ability of additives and certain synthetic lubricants to resist chemical decomposition (hydrolysis) in the presence of water.

HYDROMETER : An instrument used to determine the specific gravity (or API gravity ) of liquids, consisting of a filled bulk container topped with a narrow tube bearing a scale. The gravity is indicated by a line on the scale that coincides with the meniscus of the liquid.

HYDROPHILIC : Having an affinity for water; capable of uniting with or dissolving in water.

HYDROPHOBIC : Having an antagonism towards water; unable to unite or mix with water.

HYDROSTATIC LUBRICATION : This state of lubrication in which the lubricant is supplied to a single bearing under sufficient external pressure to separate the opposing surfaces of a continuous lubricant film.

HYDROXYSTEARATE : Term used to describe soap thickeners made by reacting a metal hydroxide (alkaline) with 12-hydroxystearic acid (fatty acid).

HYGROMETRIC : Easily able to absorb water or moisture.

HYGROSCOPIC : Capable of easily absorbing water from the air.

HYPOID GEAR : A gear construction in which a line cutting the pinion in half does not cut across the gear. That is, the pinion is offset from the gear’s centerline.

HYPOID GEAR LUBRICANT : A gear lubricant with extreme pressure characteristics for use in hypoid type gears, such as automotive differentials.

IP : The Petroleum Institute (IP) is the British equivalent of the American Society for Testing and Materials (ASTM) and defines standards and test methods, as agreed upon by stakeholders in the industry.

ISO : International Organization for Standardization. General term used to indicate an agreement between contributing countries on methods and units of measurement.

IGNITION POINT : See Automatic Ignition Point.

INCOMPATIBILITY : Two lubricating greases are incompatible when a mixture of products exhibits significantly inferior physical performance properties compared to either grease before mixing. Inferior performance or properties of one product and superior performance of the other may simply be due to mixing and should not be considered proof of incompatibility.

INDUCTION PERIOD : In an oxidation test, the period of time during which oxidation occurs at a constant and relatively low rate. It ends at the point where the oxidation rate increases sharply.

INERT : exhibits no chemical reactivity.

INHIBITOR : An additive that improves the performance of a petroleum product by controlling undesirable chemical reactions, such as oxidation inhibitors, rust inhibitors, etc.

INORGANIC : Freely, compounds not containing carbon. (See Biological).

INORGANIC THICKENER : See Soap-free thickener.

INSOLUBBLE :

IODINE NUMBER / IODINE VALUE : The percentage of iodine that will be absorbed by a chemically unsaturated substance (base oil, vegetable oil, rubber, etc.) at a given time under arbitrary conditions. A measure of unsaturation .

JOURNAL : Male part of a rotary bearing; part of the shaft or axle resting on bearings.

KEG PUMP : A grease pump mounted on top of a grease drum or tub and equipped with a chimney pipe extending to the bottom of the drum. Each pump stroke (manual or pneumatic) lifts the grease and pushes the displaced grease through a flexible hose to the application. (See Slumping) .

KETTLE GREASE : The manufacturing vessel in which a soap thickener is heated and stirred to ensure a complete reaction. Complexing agents, additives, and oil can also be added to the kettle.

KINEMATIC VISCOSITY : Kinematic viscosity is generally measured by taking the flow time of a certain volume of the product, at a fixed temperature (usually 40°C or 100°C), through a standard orifice. The SI unit of kinematic viscosity is the stoke; however, it is usually expressed as centistoke (cSt).

LACQUER : See varnish.

LEAD SCAVENGERS : Bromine and chlorine compounds included in anti-knock compounds to help remove lead compounds from the engine after fuel combustion.

LINEAR BEARING : A type of ball bearing in which the balls are arranged to move in tracks that extend axially on a shaft or slide to reduce friction in a flat plane, such as reciprocating motion.

LITHIUM /LITHIUM COMPLEX GREASE : A grease prepared from a lubricating fluid thickened with lithium soap or lithium complex soap.

LOAD – POWER SUPPLY : Properties of a lubricant to form a film on the lubricated surface, resisting rupture under given load conditions. Expressed as a maximum load, the lubricated system can withstand this without failure or excessive wear .

LOAD : The force to be borne by a component, which determines its material and structure. For the lubrication specifier, its size and direction can also determine the type of bearing and, along with other factors, influence the choice of lubricant.

LOAD – WEAR INDEX ( LWI ) : This ASTM four-ball test is used to determine a lubricant’s relative ability to prevent wear under applied loads. In the British IP test method, it is designated by the average load in hertz. (See Four-Ball Method).

LUBRICANT : A substance used to reduce friction or make surfaces slippery. The lubricant prevents adhesion between surfaces and introduces a material, solid or fluid, of sufficient consistency to maintain a shearable film. Any substance interposed between two surfaces in relative motion, thereby reducing wear friction between the surfaces.

LUBRICATION GREASE STRUCTURE : The physical arrangement of the component particles of a lubricating grease thickening additive, if present, and the liquid lubricant. It is the nature and stability of this arrangement that determine the appearance, texture, and physical properties of the lubricating grease.

LUBRICATION : Control of friction and wear by introducing a film that reduces friction between moving contacting surfaces. May be a fluid, solid, or plastic substance.

LUBRICATION INTERVAL : The time between applications of fresh lubricant . This can be calculated from the volume of an antifriction bearing in simple situations, but the interval is considerably affected by factors such as temperature and speed.

LUBRICITY : See Oily.

LUSTER : The intensity of the light reflected by the lubricating grease; its shine or brilliance. Luster should be described as follows:

MECHANICAL STABILITY ( GREASE ) : See Shear Stability.

MELTING POINT : The temperature at which a product begins to melt or change from a solid to a liquid state.

METAL DEACTIVATORS : Additives used in gasoline, diesel fuels and lubricating oils to prevent the catalytic action of metallic surfaces in order to promote oil oxidation and gum formation in gasoline and diesel fuel.

METALLIC SOAP : See soap.

MICRON : 10⁻⁶ meters; one millionth of a meter.

MINERAL HYDROCARBONE : See White Oil.

MINERAL OIL : Term applied to a wide range of products with viscosities within the range of products considered to be petroleum-type oils.

MISCIBLE : Liquids capable of forming a liquid solution or a uniform mixture of more than one type of liquid.

MIXED COMPLEX GREASE : A complex soap grease in which the incorporation of two or more metallic alkalis confers the properties of the whole in the final product.

MIXED LUBRICATION FILM : A lubrication condition in which the lubricant film is so thin that the friction between surfaces is determined by the surface properties as well as the lubricant viscosity.

MOBILITY ( GREASE ) : Analogous to fluidity, a property of a lubricating grease allowing flow under pressure, as in centralized grease distribution systems.

MOLY , MOLYSULPHIDE : See molybdenum disulfide.

MOLYBDENE DISULPHIDE : A black, lustrous powder (MoS2) used as a dry-film lubricant, particularly in high-temperature, high-load, and high-vacuum applications. It is also used in paste form to prevent scratching during press-fitting of molded parts and as an additive to impart residual anti-wear lubricating properties to oils and greases. Molybdenum disulfide is often referred to simply as “molybdenum” or “moly sulfide.”

ENGINE OIL : Engine oil is a type of liquid oil used for lubrication in various types of internal combustion engines. The use of engine oil offers other benefits, including cooling by dissipating heat from the engine’s moving parts, as well as cleaning and inhibiting corrosion in internal combustion engines. The vast majority of engine oils are derived from petroleum. Synthetic engine oils, composed of artificially synthesized compounds, currently represent a minority share of the engine oil market because they are more expensive but offer enhanced performance.

MUCK POLE : A bucket-operating device used on some Ruston Bucyrus-type face masks. The “muck pole” or “dipper pole” is a 20′ x 18′ (approximately) steel tube that slides through a brush, called a saddle block, inserted into the boom. As a highly stressed sliding member, constantly exposed to the elements, lubrication is a common issue.

MULTI – GRADE OIL : Engine or gear oil that meets the requirements of more than one SAE viscosity grade classification and can be used over a wider temperature range than a single-grade oil.

MULTI – PURPOSE GREASE : A high-quality grease that can be used in various applications.

NLGI NUMBER / NLGI GRADE : Numerical scale for classifying the consistency range of lubricating greases, based on ASTM D217 worked penetration (60 strokes) at 25 ° C (77°F). NLGI gradesare in ascending order of consistency (hardness) as follows: NLGI CONSISTENCY NUMBER WORKED PENETRATION RANGE

NAPHTHA : generic term describing a variety of light petroleum distillates such as mineral spirits and other petroleum solvents.

NAPHTHENIC : A type of petroleum fluid derived from naphthenic crude oil, containing a high proportion of closed-ring methylene groups.

NEAT CUTTING OILS : Oil used in machine tools as opposed to cutting fluid emulsions mixed with water .

Needle roller bearing : A bearing in which the rollers are several times longer than their diameter. The rollers are tightly enclosed and no cage is used. These bearings are generally used in low-speed or oscillating, high-load applications.

NEUTRAL OIL : The basis of the most commonly used automotive and diesel lubricants is light high cuts from vacuum distillation.

NEUTRALIZATION NUMBER : A measure of the acidity or alkalinity of an oil. The number is the mass in milligrams of the amount of acid (HCl) or base ( KOH ) required to neutralize one gram of oil.

NEWTONIAN BEHAVIOR : The property of simple liquids whose shear rate is proportional to the shear stress. This constant proportion is the viscosity of the liquid.

NEWTONIAN FLOW : Rheological characteristic of a fluid whose shear rate is directly proportional to the shear force, as with straight-flow quality oils that do not contain polymer viscosity modifiers. When the shear rate is not directly proportional to the shear force, the flow rate is not Newtonian, as is the case with oils containing engine oil for viscosity modifiers.

NICKEL : A ductile, hard, lustrous ferromagnetic metal used as a plating layer and which is non-oxidizing and accepts rare metal coatings. More recently described as a heavy metal whose powder must be treated as toxic by inhalation.

NITRATION : The process by which nitrogen oxides attack petroleum fluids at low temperatures, often resulting in increased viscosity and the formation of deposits.

NOISE : Imperfections in the finish and coating of an antifriction bearing and/or variations in the grease’s dispersion can lead to audible vibration levels in a high-speed bearing. This is unacceptable, for example, in audio equipment motors. The grease must be carefully selected for purity and complete homogeneity of the grease.

NON – NEWTONIAN BEHAVIOR : The property possessed by certain fluids and many plastic solids, including grease, of having a variable relationship between shear stress and shear rate. (Non-Newtonian materials, therefore, do not possess viscosity as defined by Newton, but rather an apparent viscosity, a quantitative value that can vary considerably with different shear rates. Conventional types of viscometers with uncontrolled shear rates do not satisfactorily measure non-Newtonian materials.)

NON – SOAP THICKENER : At least one of several specially treated or synthetic materials, excluding long-chain fatty acid metallic soaps, that can be either thermally or mechanically dispersed in liquid lubricants to form a lubricating grease. Some non-soap thickeners, such as polyurea, are also called SYNTHETIC THICKENER . Certain types, such as silica, are called inorganic thickeners.

NSF International : A U.S. non-profit organization dedicated to public health and the environment, which establishes quality standards related, among other things, to lubricants used near food products. NSF (H1) indicates that the product can be used in case of accidental contact with food during production. NSF (H2) indicates that a product has been deemed unsuitable for lubricating food production machinery where there is a risk of food contamination. The NSF evaluates complete product formulations and their packaging claims rather than individual ingredients, which falls under the responsibility of the FDA .

OCTANE RATE : A measure of a fuel ‘s ability to prevent detonation in a spark-ignition engine. Measured in a standard single-cylinder engine with variable compression ratios against primary reference fuels. Under mild conditions, the engine measures Research Octane Number ( RON ); under extreme conditions, Motor Octane Number ( MON ). Where regulations require octane ratings to be displayed on metering pumps, the Antiknock Index ( AKI ) is used. This is the arithmetic mean of RON and MON , (RM)/2. It approximates the Road Octane Number, which is a measure of how an “average” car responds to fuel.

OIL : A liquid of vegetable, mineral, animal or synthetic origin, slippery to the touch.

OIL PURGE : The rate at which oil is supplied to a grease to meet the requirements of the surface to be lubricated , depending on pressure and/or temperature. Oil purging therefore determines the quality and thickness of the lubrication, as well as the lubrication interval. Proper oil purging is thus an essential element to consider when choosing a grease.

SLINGER OIL : Device designed to prevent oil from creeping down a shaft.

OIL / LUBRICITY : A term used to describe a lubricant’s ability to reduce friction between floating surfaces. There are no generally accepted test methods for evaluating this property. Lubricating power is primarily important under boundary lubrication conditions and likely relates to the oil’s ability to wet bearing surfaces and resist friction. Oiliness is not directly related to the oil’s viscosity.

OILLES BEARING : Bearings made of porous metal impregnated with 10/20% oil or sometimes graphite.

OIL WEDGE : In hydrodynamic lubrication, the accumulation of lubricant waits to enter the reduction space created between two surfaces in relative motion, thus creating a high – pressure zone that tends to seek equilibrium by lifting the surfaces.

BIO : Made from carbon compounds.

ORGANICALLY MODIFIED CLAY : Chemically activated bentonite clays.

ORGANOCLAY BASE GREASE : A grease prepared from a lubricating fluid thickened with a naturally organic modified earth or clay.

OUTBOARD MOTOR : The outboard boat motor is developed as a self-contained unit with engine, auxiliary systems , and propeller, designed to be mounted at the stern (rear) of the boat. It is the most common method of propulsion for small boats.

OXIDATION : occurs when oxygen attacks petroleum fluids. The process is accelerated by heat, light, metallic catalysts, and the presence of water, acids, or solid contaminants. This leads to an increase in viscosity and the formation of deposits.

OXIDATION INHIBITOR : A substance added in small quantities to a petroleum product to increase its resistance to oxidation, thus extending its shelf life or storage time; also called an antioxidant.

OXIDATION STABILITY : resistance of a petroleum product to oxidation and, consequently, a measure of its service life or storage life.

OXYGENATE : An ashless organic compound, such as alcohol or ether, containing oxygen, which can be used as a fuel or fuel supplement.

OXYGEN COMPATIBILITY : When a substance, of synthetic or inorganic structure, resists oxidation, particularly when exposed to strong oxidizing agents.

Oxygenated fuels : Fuels for internal combustion engines that contain oxygen bound within the molecule, for example, alcohols, ethers, and esters. The term also applies to gasoline blends with oxygenated compounds, for example, Gasohol, which contains 10% by volume of anhydrous ethanol in unleaded gasoline.

PFPE : Perfluorinated polyether. A synthetic oil with exceptional oxidation, chemical and thermal stability.

PTFE : Teflon, polytetrafluoroethylene. A thermally stable, synthetic thermoplastic. Resistant to acids, alkalis, and oxidizing agents, and exhibiting an extremely low coefficient of friction. For the same reasons, PTFE possesses excellent anti-slip and non-stick properties. (See Release Agent).

PARAFFINIC : A type of petroleum fluid derived from paraffinic crude oil and containing a high proportion of straight-chain saturated hydrocarbons. Often prone to cold-flow problems.

DOUGH : A soft, smooth and thick mixture.

PENETRATION ( GREASE ) : A measure of the hardness or consistency of a solid or semi-solid material based on ASTM D217 (and similar methods standardized by other organizations). A grease penetrometer consists of a specially designed cone that penetrates grease under specific conditions of temperature, force moving the cone, time, and grease state. Penetration is the number of tenths of a millimeter that the cone penetrates into the product under the prescribed conditions. The ASTM definitions are given as follows:

PENETROMETER : Instrument for measuring the penetration of semi-solid substances such as greases.

PERMANENT PERCENTAGE LOSS ( PPVL ) : Measure of PVL related to the viscosity of new oil; equals PVL divided by the viscosity of fresh oil, multiplied by 100 .

PERCENTAGE TEMPORARY VISCOSITY LOSS ( PTVL ) : Difference between the viscosity of an oil measured at low and high shear rates, divided by the viscosity measured at a low shear rate, multiplied by 100. All viscosities must be measured at the same temperature and using the same units (cSt or cP).

POLYETHER PERFLUORINE : See PFPE .

Permanent Viscosity Loss ( PVL ) : Irreversible reduction in lubricant viscosity due to mechanical shear in engines or laboratory test benches. PVL is equal to the difference between the viscosity of fresh oil and that of degraded oil, both measured at the same temperature.

PETROLEUM GELETTE (Petrolatum) : A semi-solid, gelatinous substance derived from petroleum, composed of various alkanes and alkenes. Used in medicine (i.e., as petroleum jelly) and as a carrier for lubricating solids, as well as for temporary anti-corrosion treatment.

HYDROCARBONS RESIDUE : This fraction of crude mineral oil is removed to ensure the quality and performance of the useful fractions. Residues include waxes, bitumen, acids, dyes, etc.

pH : This measurement indicates the acidity or alkalinity of an aqueous solution. The logarithmic pH scale ranges from 0 (very acidic) to 14 (very alkaline), with a pH of 7 indicating a neutral solution equivalent to the pH of distilled water.

PICK -UP : When sliding friction and surface quality allow one sliding surface to pull off significant particles from another in relative motion, this indicates a failure of boundary lubrication.

Pillow block : Refers to a block that surrounds and supports a log or shaft; a bearing. The block is used to transfer power at a 90-degree angle and supports a transfer shaft using bearings. The shaft is secured via an eccentric center bushing that tightens onto the main bearing commutator. The pillow block is also known as a pillow block outside the United States.

PITTING : Surface cavities; may be related to fatigue, overload, or corrosion.

ORDINARY BEARINGS : Bearings whose movement slides, distinct from bearings, as anti-friction bearings, are indicated under “Bearings”.

PLASTIC FLOW : Deformation of the metal surface resulting from flow under high load. Plastic flow differs from fluid flow in that the shear stress must exceed a yield threshold before any flow occurs.

PLASTICITY : Property of an apparently solid material that allows it to deform permanently under the effect of a force, without breaking.

PLUMMER BLOCK : See pillow block.

POISE (P) : Unit of measurement for a fluid’s resistance to flow, i.e., viscosity, defined as the shear stress (in dynes per square centimeter) required to move one fluid layer over another over a total thickness of one centimeter at a speed of one centimeter per second. This viscosity is independent of the fluid’s density and directly related to the resistance to flow.

POLAR COMPOUND : A chemical compound whose molecules have electrically positive characteristics at one end and negative at the other. Polar compounds are used as additives in many petroleum products. Polarity gives some molecules a strong affinity for solid surfaces. As lubricant additives (wetting agents), these molecules deposit in a tenacious film, reducing friction. Some polar molecules are oil-soluble at one end and water-soluble at the other. In lubricants, they act as emulsifiers, contributing to the formation of stable oil-in-water emulsions. These lubricants are said to have good metal-wetting properties. Polar compounds that are highly attractive to solid contaminants act as detergents in motor oils by keeping contaminants finely dispersed.

POLISHING ( BORE ) : Excessive smoothing of the surface condition of the cylinder bore or cylinder liner in an engine to a mirror-like appearance, resulting in damping of ring closure and oil consumption performance.

POLYAKYLENE GLYCOL ( PAG ) : Synthetic oils with a good viscosity index and a very low tendency to carbonization.

POLYMER : A substance formed from repeated bonds of natural and synthetic compounds, generally of high molecular weight, as in plastics and elastomers.

POLYMERIZATION : The creation of a polymer through a chemical reaction. An undesirable reaction in oils resulting in a dramatic increase in viscosity. Sometimes loosely used to describe gum formation at high temperatures or the effect of mixing two different base oils.

POLYTETRAFLUOROETHYLENE : See PTFE .

POLYUREA GREASE : A grease consisting of a lubricating fluid thickened with a polyurea thickener or polyurea complex. Polyurea is created by the chemical reaction between an isocyanate and an amine.

Positive crankcase ventilation ( PCV ) : A system that vents crankcase exhaust gases and redirects them through the carburetor intake manifold to the combustion chamber where recycled hydrocarbons are burned. A PCV valve controls the crankcase gas flow to reduce hydrocarbon emissions.

VERSE POINT : An indicator of the ability of a distilled oil or fuel to flow at cold operating temperatures. It is the lowest temperature at which the fluid will flow once cooled under prescribed conditions .

FOR DEPRESSANT POINT : Additive used to lower the pour point or low-temperature, low-shear fluidity of a petroleum product. Prevents oil-insoluble wax molecules from forming a honeycomb (network-like structure) at colder temperatures. Particularly useful for paraffinic oils. Provides useful low-temperature pourability; acts as an antifreeze for oil.

PRE – TREATMENT : Solid lubrication applied to provide wear protection under a fluid lubricant or grease.

PROPELLANT : A volatile gas or liquid that, when allowed to escape from a pressurized container, carries with it particles or droplets of another mixed or suspended material in aerosol form. Propane and butane are common petroleum-derived propellants that have replaced CFCs . Carbon dioxide, compressed air, and nitrogen are also used as propellants, each with its own advantages and disadvantages.

PUMPABILITY : Viscosity characteristics of an oil at low temperatures and low stress and shear rates that allow satisfactory flow to and from the engine oil pump and subsequent lubrication of moving components. This also indicates the “resistance to flow” of the grease in the grease pump lines. Soft, buttery greases are easy to pump. Hard, fibrous greases are difficult to pump. The ability of a lubricating grease to flow under pressure through the line, nozzle, and fitting of a grease distribution system. Apparent viscosity at moderate shear rates is the best indicator.

PYCNOMETER : A device for measuring liquid densities.

PYROLYSIS : Chemical decomposition under the action of heat.

QUENCHING OILS : Oils used in quenching baths to control the cooling rate of metals, especially steel, in order to obtain specific desired properties such as ductility, hardness, strength, etc.

R&O OIL : Oil mixed with chemical agents to prevent rust formation in turbine lubrication systems and to minimize oil oxidation.

RADIAL : Reference to loads and forces in a bearing having vectors at 90 degrees to the rotational component.

EFFECTS OF RADIATION : Mineral oils, in particular, are affected by accumulated radioactivity in that they produce effects similar to those of high evaporation, i.e., increased viscosity. Some oils have improved radiation stability, and in general, dry-film lubricants that use solids such as molybdenum disulfide or graphite are well suited.

RE- REFINING : Process of recovering used lubricating oils and bringing them back to a condition similar to that of virgin stocks by filtration, adsorption on clay or more elaborate methods.

CLAIMED OILS : This term should only apply to used oils treated by relatively simple processes, such as filtration or centrifugation, which are primarily aimed at removing foreign contaminants.

REDWOOD SECONDS : A practical viscosity unit indicating the time it takes for an oil to flow through the tube in a Redwood viscometer (See Brookfield, Engler, Saybolt).

REFINING : A series of processes for converting crude oil and its fractions into finished petroleum products, including thermal cracking, catalytic cracking, polymerization, alkylation, reforming, hydrocracking, hydroforming, hydrogenation, hydrogen treatment, refining, solvent pickling, dewaxing, oil removal, acid treatment, clay filtration and asphalting.

RELEASE AGENT : Film applied to the mold contour to allow removal of a newly molded component while protecting the finish of the mold and components.

REPEATABILITY : A measure of the reliability of test results obtained with the same device on multiple occasions.

REPRODUCIBILITY : A measure of the reliability of tests performed on different, but essentially identical, devices by different operators and in different laboratories. To be valid, a test must produce the same results regardless of who performs it.

RESIDUAL FUEL : Fuel consisting primarily of the liquid matter remaining after the distillation of crude oil. Generally high in sulfur but relatively inexpensive. Widely used in high-efficiency, low-speed marine diesel engines.

RHEOLOGY : The study of the deformation and/or flow of matter in terms of stress, strain, temperature, and time. The rheological properties of lubricating greases are commonly measured by penetration and apparent viscosity.

RHEOPECTIC GREASE : A grease whose consistency at work is agitated or stirred as little as would be caused by its pumping in a grease distribution line.

CONDUCTION : In gears, plastic flow characterized by a wrinkled appearance on the surface.

BEARING OIL RING : Consists of a large diameter ring placed around the journal and immersed in an oil reservoir. The rotation of the journal also causes the ring to rotate, but at a slower speed due to slippage, and also transports the oil from the reservoir to the bearing.

RING SEAL : Freezing of a piston ring in its groove in a piston engine or reciprocating compressor due to significant deposits in the piston ring area.

RINGS : Circular metal elements that slide in the grooves of a piston and provide a compression seal during combustion. Also used to distribute oil for lubrication.

ROLLER BEARING : An anti – friction bearing with cylindrical rolling elements instead of balls. Typically used where high loads must be supported, roller bearings are generally radial, although thrust roller bearings are used in more specialized applications.

ROLLING AND PEENING : In gear teeth, a form of plastic flow that gives the surface a hammered appearance; the metal can be rolled over the tips of the teeth.

ROLLER BEARING : See Anti-friction Bearing .

ROLLING STABILITY : Resistance to failure due to grease in an anti-friction bearing. See Rolling stability test. (See Shear stability, consistency) .

ROPE LUBRICATION : Wire rope strands fail due to bending and tension fatigue, slip wear, and corrosion. A “dressing” or grease must have all the traditional lubricating properties, but especially the correct consistency to allow complete penetration into the core, as well as exceptional protection against wear and corrosion.

RUNNING -IN : Newly machined surfaces have numerous asperities that create highly loaded “peaks” to weld and break up with lubricant, accelerating wear rates. Even in highly polished components, a degree of polishing will be necessary to reduce the load per unit area. Running-in is a normal engineering practice, but it must be carefully controlled and monitored to ensure that the final lubricating film is not contaminated by excessive wear debris.

RUST INHIBITOR : A type of corrosion inhibitor used in lubricants to protect lubricated surfaces from rust.

ANTI – RUST : Compound for coating metal surfaces with a film that protects against rust. Commonly used to preserve stored equipment.

SAE : Society of Automotive Engineers; an organization composed of people interested in and connected to the automotive and aerospace industries. Their numerous standards committees work on parts standardization, nomenclature, and scientific investigations.

SAE NUMBER (Grade) : Numbers applied to engine crankcase, transmission and rear axle lubricants to indicate their viscosity range.

SAPONIFICATION : The process of soap formation (see Definition of soap).

SAPONIFICATION NUMBER : The number of milligrams of potassium hydroxide required to react with all the fats and fatty acids in a one-gram sample. This is a method for determining the quality of the mixture in gear oil, steam cylinder oil , or other compound lubricants.

SATURATED VAPOR : The vapor formed in a closed container upon contact with water is called saturated vapor. Dry saturated vapor is vapor that does not carry any suspended water.

SAYBOLT VISCOMETER : an industrial viscometer of the standard efflux type in the United States. It is now obsolete. There are two types: the Saybolt Universal for lubricating oils and the Saybolt Furol for more viscous materials. The word “Furol” is a contraction of the phrase “Gasoline and road oils”.

SCAR DIAMETER : Measurement taken after each “test” in a four – ball test. The dimensions obtained indicate the wear resistance of a lubricant. (See Load-Wear Index).

SCRUBBING : A washing process used in the textile industry, where they generally use their own formulas for making the scouring agent, which is usually an alkaline, aqueous solution.

Piston ring scraper : A piston ring with a chamfered front or upper edge, designed to return excess oil from the cylinder walls to the crankcase. Primarily used in internal combustion engines.

SCRATCHES : Fine abrasive grooves in the direction of sliding.

SCUFFING : Abnormal engine wear due to localized welding and breakage. It can be prevented by using anti-wear, extreme-pressure, and friction modifier additives.

Gear galling : When loads are heavy and the oil film strength is insufficient to support the load, a sharp edge forms on the pitch line. This will cause the gear and a halo effect on the pitch line of the drive gear. In severe cases, the metal wears down on the faces and flanks of the gear teeth. Also known as galling.

SEAL : Flexible component mounted outside the rotating parts of an anti-friction bearing and rotating with the bearing against a fixed part to prevent the ingress of contaminants.

SEIZURE : Sticking due to expansion caused by heat, friction, or scratches.

GEAR SEIZURE : An extreme case of gear seizure where the lubricating film fails, and due to high local temperatures, the contacting surfaces weld together. These damaged areas naturally cause marks on the surface of the successive teeth.

SEPARATION : The unwanted release of oil from the body of stored fat. (See Bleeding).

SET : In the manufacture of a lubricating grease, one goes from a fluid state to a semi-fluid or plastic state.

SETT GREASE : Lubricating oil prepared by mixing a mineral oil suspension with an alkali and a mineral oil fatty acid solution. Saponification is usually complete once the mixture is poured into the shipping container. Because the mixture temperature is typically below 140°F, these products are sometimes known as cold curing greases. Axle grease is generally a settling grease.

SHEAR : stress causing parts of a body to bend and slide against each other. Fat is sheared by agitation.

SHEAR RATE : The rate of slip within a flowing substance. The mean or average shear rate in a pipe or tube is the average velocity divided by the tube radius. It therefore has the dimensions of the inverse of time and is usually expressed in units of reciprocal seconds (s⁻¹). The mean shear rate is given in the determination of apparent viscosity in ASTM D1092 .

SHEAR STABILITY ( GREASE ) : The ability of a lubricating grease to resist changes in consistency (hardness) during mechanical work. This can be performed on various types of laboratory or operational equipment. This can also be referred to as MECHANICAL STABILITY .

SHEAR STABILITY INDEX ( SSI ) : A measure of the irreversible viscosity loss of an oil attributable to the viscosity modifier when the oil is subjected to engine operation or specific test conditions. Also sometimes called the Permanent Shear Stability Index ( PSSI ) , SSI is defined by the equation: SSI = 100 (Vo-Vs) / (Vo-Vb), where Vo = viscosity of the unsheared oil, Vs = viscosity of the sheared oil, and Vb = viscosity of the base oil.

SHEAR STRESS : The force required to cause a substance to shear. In fluids, the relationship between shear stress and shear rate is the viscosity of the substance.

SHEAR : sliding or slipping of a part of a substance relative to an adjacent part of a solid; this action involves cutting or breaking the crystalline structure, but in a plastic fluid, shear does not necessarily destroy the continuous nature of the substance.

SHIELD : A pressed ring placed outside rotating parts and between the rings of a ball bearing to provide a measure of protection against radiated heat.

SILICA THICKENER : A relatively inert inorganic powder used especially for thickening greases with silicone oils. (See thickener).

SILICONES : Compounds that can be likened to hydrocarbons in many respects, but the molecular chain consists of silicone atoms bonded to a carbon atom. Due to their unique temperature stability characteristics, silicones are widely used in specialty greases, etc.

SLIDING : The form of friction involved in the rubbing of surfaces, as opposed to rolling. The resulting wear is costly in terms of parts, labor, and downtime. The study of friction and wear is called tribology. It is the function of a lubricant to interpose itself between sliding surfaces to reduce friction and therefore wear.

SLUDGE : Thick, dark residue, usually with a mayonnaise-like consistency, that accumulates on the internal surfaces of stationary engines. It is generally removable by wiping unless it has a carbonaceous consistency; its formation is associated with an insoluble lubricant overload.

SLUMPABILITY ( GREASE ) : A property of certain greases that makes them partially self-leveling. Greases with this property will be pumped from a container without the need for a follower plate. (See the definition of a follower plate.) This property is often confused with PUMPABILITY (see the definition).

SOAP : A specific type of salt formed by the reaction of a fatty acid with an alkali.

SODIUM COMPLEX GREASE : Grease prepared from a lubricating fluid thickened with special sodium soaps and/or complex agents. Sodium complex grease generally has better properties, such as water and high-temperature resistance, than ordinary sodium grease.

SODIUM SOAP GREASE : Also called Soda Grease, a grease prepared from a lubricating fluid thickened with sodium soap.

SOL : A suspension of particles of colloidal dimensions in a liquid, which possesses the
gross properties of a liquid.

SOLID FILM LUBRICANT / SOLID BONDED LUBRICANT : Materials with inherent lubricating properties that are firmly bonded to the surface of a substrate by certain methods. These methods include a bonding agent, burnishing, mechanical impact, or vacuum deposition.

SOLID LUBRICANT : Any class of lubricant in which the reduction of friction and wear during sliding is caused by shear occurring within the crystalline structure of a low-shear-strength material in a particular plane. Examples include graphite, molybdenum disulfide, and certain soaps. Lubricating grease is not a solid lubricant but may contain solid lubricants as additives.

SOLUBLE CUTTING OILS : Mineral oil blended with suitable agents to allow the formation of emulsions with water. Although all cutting oils act as both a coolant and a lubricant, water is more effective as a coolant than oil, and for certain types of work, it is necessary to combine the two to achieve the most satisfactory results.

SOLVENT : A compound with a strong capacity to dissolve a given substance. The most common petroleum-based solvents are white spirit, xylene, toluene, hexane, heptane, and naphtha. Aromatic solvents have the highest solubilization for organic chemicals, followed by naphthenes and paraffins. In most applications, the solvent disappears, usually through evaporation, after fulfilling its function. The evaporation rate of a solvent is very important in manufacturing: cement and delicate plastic cleaners often require a fast-drying solvent, while adhesives that must remain tacky during processing require a slower-drying solvent. Solvents have a wide variety of industrial applications, including the manufacture of pains, inks, cleaning products, adhesives, and petrochemicals. Other types of solvents have important applications in refining and aerosols. (See Solvent extraction, Solvent refining).

SOLVENT EXTRACTION : Refining process used to separate reactive components (unsaturated hydrocarbons) from lubricant distillates in order to improve oil oxidation stability, viscosity index and additive response.

SOLVENT REFINING : A process for extracting lubricating base oils from heavy gas oil or other extracted heavy crude stream , using selective solvents such as furfural or phenol.

SPALLING : Severe damage characterized by large pits, cavities and associated cracks; related to overload and fatigue.

SPECIFICATIONS : Prescribed limits of control tests used to maintain the uniformity of a specific product.

SPECIFIC GRAVITY : Ratio between the weight (in air) of a given volume of a material and the weight (in air) of an equal volume of water at the indicated temperatures.

SPEED FACTOR : Centrifugal force and accelerations will throw oil onto the surfaces inside a bearing, resulting in inadequate lubricant supply and thin-film lubrication. Under these conditions, oxidation will be accelerated. For these reasons, grease velocity is evaluated based on the bearing size. This assessment is based on viscosity, thickener type, and oil content. In the laboratory, apparent viscosity is used to indicate high-speed performance. (See Dn). A dN result greater than 1 million generally indicates the use of petroleum. For material stress reasons, the bearing is also assigned a “speed factor.”

SPLASH LUBRICATION : A lubrication method in which oil in a bath is splashed by the moving mechanism into parts requiring a reservoir of lubricant .

SPUR GEAR : Cylinder, wheel or disc on the surface of which parallel teeth are cut, each in the same plane as the axis.

SQUEEZE FILM LUBRICATION : This lubrication state occurs when surfaces heavily coated or flooded with lubricant approach each other at a speed sufficient to generate enough fluid pressure to withstand a short-duration load. Due to viscosity (or apparent viscosity), the lubricant cannot immediately flow from the contact area. This occurs, for example, between gear teeth and between spindles and their bushings.

STABILIZER : A chemical additive that mitigates the effects of product deterioration due to its required operating conditions; that is, oxidation at temperature would be neutralized by the use of an “antioxidant”. (See, for example, Oxidation Inhibitor).

STABILITY : Used to indicate resistance to breakage under particular conditions, such as shear stability.

STEAM CYLINDER OILS : The steam engine is unique in that the lubricating oil is not applied directly to the cylinder walls or valuable surfaces, but is distributed by the steam after it has been loaded or impregnated with oil from a lubricator in the main steam line adjacent to the valuable cylinder. Steam cylinder oils must have relatively high viscosity and good wettability so that the lubricating film adheres well to the valve seats and cylinder walls, resists steam washout, and resists the effects of wear or scraping on the valves and piston rings. To operate in wet steam conditions, the oil is usually compounded.

STEARATE : A salt or ester of stearic acid. Used, very loosely, to refer to soap thickeners. (See Hydroxystearate).

STEP -UP PUMP : A pump that increases the discharge pressure in stages.

Stick – slip motion : The irregular movement of adjacent surfaces, generally at low speeds, where initial friction exceeds friction due to the jerky motion, making precise adjustments very difficult. This stick-slip is overcome by introducing a low-friction film between the sliding surfaces.

STOKE (St) : Unit of measurement of kinematic viscosity defined by the ratio of the dynamic viscosity of the fluid to its density. Usually expressed in centistokes (cSt), where 1 Stoke = 100 cSt and 1 cSt = 1 mm2 / s.

STRAIGHT MINERAL OIL : A petroleum oil that does not contain compounds (animal or vegetable oils) or chemical additives.

SSU : Saybolt Seconds Universal. A unit of measurement for the viscosity of lubricating oil commonly used in the United States.

SULFIDED CUTTING OILS : Cutting oils containing sulfur and used for difficult machining operations, such as high-speed threading and tapping, broaching, and hard-to-machine alloy steels.

SUPER – STEAM HEATER : If more heat is added to the steam after all the water it contains has been transferred into the steam, the temperature of the steam will be higher than that of ordinary saturation steam having the same pressure.

SURFACE TENSION : The attractive force exerted by molecules below the surface on molecules at the surface/air interface. Surface tension varies with the polarity of the liquid: highly polar substances like water have a higher surface tension than weakly polar substances such as oils .

SURFACTANT : An additive that reduces the surface tension of a liquid. In a lubricating oil, a surfactant can increase its affinity for metals. A surface-active agent.

SUSPENSION : In which relatively large solid particles are dispersed in a liquid. Usually poorly suspended due to particle size or the lack of polar additives, etc., and therefore requiring stirring to maintain satisfactory dispersion. Non-colloidal.

SYNERESIS : Loss of liquid lubricant from a lubricating grease due to shrinkage or rearrangement of its structure. The shrinkage may be caused by physical or chemical changes in the thickening agent. Syneresis is a form of bleeding.

SYNTHETIC HYDROCARBON : Artificial reproduction of a natural mineral oil product, but without undesirable aromatics, etc. (see Hydrocarbon).

SYNTHETIC LUBRICANT : Lubricating fluid obtained by the chemical reaction of materials of a specific chemical composition to produce a compound with planned and predictable properties.

SYNTHETIC OIL : Synthetic fluids possessing deliberately formulated properties, such as high-temperature performance. (See Silicones, PFPE ).

SYNTHETIC THICKENER : See Soap-free thickener.

TACKINESS ADDITIVE : A highly viscous additive to improve the ability of products to adhere to surfaces to be lubricated .

TACKY : Descriptive term applied to greases that seem particularly sticky or adhesive.

TAN ( TOTAL BASE NUMBER ) : neutralization number intended to measure all acidic and acidic materials in the lubricant, including strong and weak acids.

CLOSED TANK : Name given to the collection of oil storage tanks.

TAPER ROLLER BEARING : an anti-friction bearing in which the rollers are inclined far parallel to the shaft axis, thus providing a thrust reaction vector.

TBN ( Total Base Number ) : This neutralization number measures all the basic (alkaline) substances in the lubricant, such as the acid-neutralizing components in the lubricant additive. A high TBN is desirable in a crankcase oil to limit corrosive engine wear caused by combustion acids.

TECHNICAL WHITE OILS : white oils that do not meet the requirements of the USP (United States Pharmacopeia), but which have many industrial applications.

Temporary Shear Stability Index ( TSSI ): This index measures the viscosity of the modifying agent’s contribution to viscosity loss as a percentage of the oil under high shear conditions. Temporary shear loss results from the reversible decrease in viscosity in high-shear areas of the engine, an effect that can positively impact fuel economy and cold-start speed.

TEMPORARY VISCOSITY LOSS ( TVL ) : Difference between the dynamic viscosity measured at a high shear rate and that determined at a low shear rate. Both viscosities are measured at the same temperature.

TENSE STRENGTH : The force required to break a bar of a given cross-section under tension. Tensile strength depends not only on the cohesion of the material, but also on its consistency and therefore depends, at least to some extent, on the rate at which the load is applied.

TEXTURE ( GREASE ) : This property of lubricating grease is observed when a small, separated portion is pressed together and then slowly separated. TEXTURE should be described in the following terms:

THERMAL STABILITY : A lubricant’s ability to resist oxidation under high-temperature operating conditions.

THICKENING AGENT ( THICKENER ) : Solid particles that are dispersed relatively uniformly to form the lubricating grease structure in which the liquid is retained by surface tension and other physical forces.

THICK FILM LUBRICATION : See Hydrodynamic Lubrication .

THIN LAYER LUBRICATION : (See Boundary Lubrication) .

THIXOTROPE : Change in coherence due to agitation, trembling, vibration, etc., and returning to correct rigidity when left to rest.

THIXOTROPY ( GREASE ) : This property manifests as a decrease in consistency or softening following shear, followed by an increase in consistency or hardening that begins after shearing ceases. (Thixotropic hardening is a relatively prolonged process, proportional to the aging time and rarely, if ever, complete, whereas the apparent increase in viscosity that occurs in non-Newtonian systems with a decreasing shear rate is instantaneous and totally reversible. Lubricating grease is both thixotropic and non-Newtonian.)

Thrust bearings : These bearings support a load acting in the direction of the bearing axis. They can be simple, anti-friction , or incorporate special sliding elements.

TIMKEN EP TEST : Measures the extreme pressure (EP) properties of a lubricating oil. The test uses a Timken machine, consisting of a fixed block pushed upward, by means of a lever arm system, against the rotating outer raceway of a roller bearing lubricated by the product under test. The test continues under increasing load (pressure) until a measurable wear scar forms on the block. Timken OK Load is the heaviest load a lubricant can withstand before the block is scratched. (See Notation, Timken Tester).

TIMKEN ‘OK’ LOAD : (See Timken test machine).

TORQUE : Force that produces or tends to produce rotation or torsion.

ROBUSTNESS : The property of yielding to force without breaking.

TOXICITY : The degree to which a toxin (poison) is toxic.

TENSILE LIQUID : The fluid exhibits high tensile coefficients. Under high stress, it develops a glass – like structure, simultaneously transmitting shear forces and protecting the contacting surfaces from wear.

TRIBOLOGY : The science of interactions between surfaces moving relative to each other, including the study of lubrication, friction, and wear.

TURBULENCE : Rapid movement of the air/fuel mixture in an internal combustion engine that affects the combustion rate.

UNCOMPRESSED OIL : Straight mineral oil.

UNSATURATED : A term applied to carbon compounds in which some of the carbon atoms are held together by double or triple bonds, allowing these compounds to combine directly with other elements or compounds. Lubricants containing unsaturated materials are generally somewhat unstable and prone to oxidation.

VALVE LEVER : Sometimes called a “cam follower,” this is a component in engine designs that uses a linkage system between a cam and the valve it actuates. The lifter typically translates the cam’s rotational motion into a reciprocating linear motion within the linkage system.

VAPOR – PHASE CORROSION INHIBITOR : This corrosion inhibitor is in vapor form and consists of fine, volatile powders. After vaporization, it is absorbed by metal surfaces .

VAPOR PRESSURE : A measure of the volatility of a liquid at specified temperatures and pressures (or under vacuum) .

VARNISH : A thin, insoluble, and non-wipeable film forms on the internal engine parts. This can cause sticking and malfunction of moving parts with limited clearance. This lacquer is commonly used in diesel engines.

VEGETABLE OIL : An oil produced from vegetable matter, such as flaxseed or rapeseed. Although they often do not offer the same load and temperature performance as mineral or synthetic oils, they are food-safe and relatively inexpensive.

VELOCITY : Rate of movement time in a fixed direction.

VIBRATION : Rapid oscillation or alternating motion. Abrupt reversals of motion in a system can lead to boundary lubrication failure without careful design. Vibrations often cause a thixotropic reaction in grease gels, resulting in excessive loss of consistency.

VISCOMETER / VISCOSIMETER : A device used to determine the viscosity of a lubricant.

VISCOSITY : Viscosity can be considered a measure of the internal resistance to flow of a fluid, semi-fluid, or semi-solid substance. Its numerical value is based on the ratio of shear stress to shear rate during flow. Viscosities are generally defined by their absolute or dynamic viscosity and their kinematic viscosity.

VISCOSITY LEVEL : one of several systems characterizing lubricants based on viscosity for particular applications, such as industrial oils, gear oils, automotive engine oils, automotive gear oils ,and aircraft piston engine oils. Commonly used systems are ISO and SAE .

VI IMPROVER : Material added to a fluid that modifies the characteristic viscosity of the fluid and increases its viscosity index: hence the name VI Improver.

VISCOSITY INDEX (VI) : The relationship between the viscosity and temperature of a fluid. It is determined by measuring the kinematic viscosities of the oil at 40 and 100 °C and using the tables or formulas included in ASTM D 2270. Fluids with a high viscosity index tend to exhibit less viscosity change with temperature than fluids with a low viscosity index.

VISCOSITY MODIFIER : Lubricant additive, usually a polymer, whose function is to provide beneficial rheological properties for lubricating oils, such as reducing the tendency of an oil’s viscosity to change with temperature.

VOLATILITY : The tendency of a product to change from a liquid to a vapor state. This property is, of course, very important in gasoline.

WATER DISPLACEMENT : The ability of many oil – based products to “wet” the metal surface with a protective film to prevent corrosion. (See wetting agent).

Water Regulations Advisory Service ( WRAS ) : Promotes awareness of water regulations throughout the UK. WRAS assesses material tests and publishes satisfactory materials in the program’s “Water Fittings and Materials Directory”.

WATER RESISTANCE : The ability of a lubricating grease to withstand the addition of water to the lubrication system without adverse effects. Water resistance is generally considered to be composed of four components listed below:

WAX : A viscous or solid, heat-sensitive substance, natural or synthetic, generally insoluble in water but readily soluble in most organic solvents. Waxes are commonly used as carriers for active ingredients in a wide range of products used at the industrial and national levels. In lubrication, waxes are notably used to impart water resistance. The development of wax at low temperatures in paraffinic oils is undesirable, and its removal is a goal of solvent refining.

WEAR : Removal of material from surfaces in relative motion. Three types of wear are described below:

WELDING : To fuse heat and/or pressure.

HUMID VAPOR : Vapor containing tiny suspended water globules.

WETTING AGENT : An additive that encourages an oil to spread and adhere more intimately to a surface to improve boundary layer lubrication and corrosion protection.

WHITE METAL : Bearing alloy of lead, antimony and copper.

WHITE OIL or WHITE MINERAL OIL : A highly refined lubricant used for specialized applications such as cosmetics and pharmaceuticals. White oil must generally meet the requirements of the USP (United States Pharmacopeia) or NF (National Formulary).

WICK FEED CUPS : greasers, comprising oil reservoirs or cups in which one end of a wick of cotton, felt, wool, etc. dips into the oil and by capillary action drains the oil into the bearing to be lubricated.

WORKED PENETRATION : The penetration of a grease sample immediately after it has been brought to a temperature of 25°C (77°F), then subjected to 60 double blows in a standard greaser.

WORK : Term used to indicate the shearing and churning of grease in an anti-friction bearing (See Penetration).

WORM GEAR : The two members of a worm gear set are known as the workpiece and the wheel or worm gear. The worm resembles a screw, although it is a special type of helical gear and its teeth are referred to as the thread.

WRAS : See Water Regulation Advisory Scheme.

YIELD (OF LUBRICATING GREASE ) : The amount of grease of a given consistency that can be obtained with a defined amount of thickening agent. As the yield increases, the percentage of thickener decreases.

YIELD POINT or YIELD STRESS : The minimum shear stress required to produce a flow of plastic material. It is estimated by the intersection of the shear stress axis with the shear stress – shear rate curve, by extrapolating from the right-hand side of the curve.

GREASE FITTING : A common grease fitting, one of the types of fittings used in lubrication.

ZINC ( ZDDP or ZDTP ) : Commonly used name for zinc dialkyldithiophosphate or zinc dithiophosphate, an anti-wear/anti-oxidation chemical.

This site is registered on wpml.org as a development site. Switch to a production site key to remove this banner.