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Boundary Lubrication – A lubrication regime in which the film of lubricant is too thin so that surface-to-surface contact takes place over a large area and the load is carried by a very thin film of lubricant. Also referred to thin film, imperfect, or non-viscous lubrication.
Hydrodynamic Lubrication – A system of lubrication in which the shape and relative motion of the sliding surfaces causes the formation of a fluid film having sufficient pressure to separate the surfaces. This regime provides the best lubricating conditions when the two moving surfaces are completely separated by a relatively thick film of lubricant.
Mixed Lubrication – The lubrication regime which exists when moving surfaces are separated by a continuous film of lubricant with a thickness comparable to the roughness of the surfaces.
Oil Mist Lubrication – A system of lubrication used in some gearboxes in which the lubricant is atomised and sprayed into the gearbox in a stream
of dry compressed air.
Splash Lubrication – A system of lubrication in which parts of a mechanism dip into and splash lubricant onto themselves and/or other parts of the mechanism.
Spray Lubrication – A system of lubrication in which the lubricant is sprayed directly on to the surfaces to be lubricated.
Anti-foaming Agent – An additive included in some lubricant formulations to suppress foam formation.
Anti-oxidant Additive – An additive included in some lubricant formations to inhibit the chemical breakdown of the base oil and some additive constituents by reaction with oxygen.
Anti-scuffing Additive – An additive included in some lubricant formulations that is absorbed on to metal surfaces to prevent direct metal-to-metal contact.
Anti-wear Additive – An additive included in some lubricant formulations to reduce friction and wear.
Corrosion Inhibitor – An additive included in some lubricant formulations to help the lubricant protect against corrosion.
Detergent – An additive included in most engine oil formulations to inhibit deposit formation and protect the lubricated surfaces, having the property of keeping insoluble matter in suspension thus preventing its deposition where it would be harmful. A detergent may also redisperse deposits already formed.
Dispersant – An additive included in some lubricated formulations to hold insoluble contaminants in suspension. In engine oils it helps prevent the formation of sludge, varnish and other engine deposits by keeping particles suspended in colloidal state (suspension of finely divided particles).
Extreme Pressure (EP) Additive – A chemical compound imparting extreme pressure characteristics to a lubricant with the objective of reducing wear under conditions where rubbing or sliding accompanies high contact pressures. Under heavy loads, EP additives form a protective chemical film on the surfaces in contact.
Metal Deactivator – An organic type of additive having the property of suppressing the catalytic action of metal surfaces and traces of metallic materials exposed to petroleum products which, in the absence of the deactivator, would catalyse gum formation and other oxidation.
Non-soap Thickener – A substance such as clay, silica gel, carbon black, or any of several specially treated or synthetic materials that can be either thermally or mechanically dispersed in liquid lubricants to form lubricating grease. Also called synthetic thickener. Certain types are called inorganic thickeners.
Pour Point Depressant – An additive which lowers the pour point of petroleum products by reducing the tendency of the waxes present to coagulate into a
Rust Inhibitor – An additive included in some lubricant formulations to restrict the formation of rust on lubricated surfaces.
Stabiliser – An additive which may be included in some grease formulations to ensure that the base oil and thickener form a stable mixture with a uniform composition.
Tackiness Additive – An additive which may be included in the formulation of lubricants for slideways and open gears to help the lubricant adhere more effectively
Thickening Agent – A substance used in making greases which is mixed with base oil to produce a stable semi-solid product.
Abrasion – In gears, a type of wear caused when hard particles are trapped between gear teeth.
Bore Polishing – Excessive smoothing out of the surface finish of the cylinder bore in an engine to a mirror-like appearance, resulting in depreciation of ring sealing performance. Bore polishing often leads to an increase in oil consumption and wear and to a decrease in engine efficiency.
Cavitation – The formation of pockets of air or vapour in a fluid when the pressure on the fluid is reduced.
Lacquer – A hard, shiny, transparent surface coating usually found in engines and derived from a deposit resulting from the oxidation and polymerisation of fuels and lubricants when exposed to high temperatures. Similar to but harder than varnish.
Pitting – In gears, a type of wear in which cracks develop in gear teeth because of metal fatigue caused by overloading.
Scavenging – The removal of waste gases from the cylinder of a two-stroke internal combustion engine.
Scoring – The same as scuffing.
Scuffing – In gears, a type of wear which develops when direct
metal-to-metal contact takes place between gear teeth.
Sludge – The soft deposits, usually dark coloured, formed in lubrication systems, mainly consisting of oxidised lubricating oil components, water and in internal combustion engines, carbonaceous residues from fuel combustion. A black sooty deposit which usually forms in engines as a result of oil oxidation and ineffective dispersancy.
Squawk – A harsh abrupt sound sometimes emitted by oil-immersed braking systems.
Stick-slip – A jerky type of motion in which a moving part of a machine tends to stick as static friction builds up to a maximum and then slips as the static friction is overcome.
Absolute Viscosity – A term used interchangeably with viscosity to distinguish it from kinematic viscosity of commercial viscosity. It is occasionally referred to as dynamic viscosity.
Air Release – The ability of a fluid to allow the escape of air entrained within it.
Biodegradability – The capacity of a substance to be broken down by the biological action of living organisms.
Apparent Viscosity (of a grease) – A measure of the resistance to flow of a grease whose viscosity varies with both temperature and flow rate.
Bleeding – The tendency of a liquid component to separate from a solid or semi-solid mixture such as an oil from a grease. Some bleeding is desirable, since it provides continuous oil lubrication to bearings.
Chemical Stability – The ability of a substance to resist chemical breakdown.
Compatibility – The ability of substances to exist together without damaging each other.
Demulsification – The separation of an emulsion into its component liquids.
Emulsion – A mechanical mixture of two immiscible liquids such as oil and water. Water-in-oil emulsions have water as the internal phase and oil as the external. Oil-in-water emulsions have water as the external phase and oil as the internal.
Film Strength – The ability of a film of oil or grease to resist rupture due to load, speed, temperature and shock loading, which enables it to maintain an unbroken film on lubricated surfaces under operating conditions, where otherwise there would be scuffing or scoring of the surfaces.
Filterability – The ability of a liquid to pass freely through a filter without clogging it.
Flammability – Capable of being ignited and burning.
Flash Point – The lowest temperature of a liquid at which it will give off sufficient vapour to form a flammable mixture with air above the liquid which will ignite momentarily (i.e. flash) when exposed to a flame.
Friction – The resisting force encountered at the common boundary between two bodies when, under the action of an external force, one body moves or tends to move over the surface of the other.
Incompatibility – Incompatibility occurs when a mixture of two lubricants results in physical properties or performance markedly inferior to those of the individual products. Performance or properties inferior to one of the products but superior to the other may be due to simple mixing and is not considered evidence of incompatibility.
Kinematic Viscosity – A definition of viscosity commonly used by lubricant manufacturers. It is equal to the dynamic viscosity of a liquid divided by its density. In a c.g.s. system, the standard unit of kinematic viscosity is the stoke and is expressed in sq. cm. per. sec.
Miscibility – The tendency or capacity of two or more liquids to form a uniform blend, that is, to dissolve in each other. Degrees are total miscibility, partial miscibility and immiscibility.
Oil Separation – In greases, the separation of the base oil from the thickener.
Oxidation Stability – The resistance of a petroleum product to oxidation, hence a measure of its potential service or storage life. The available tests all simulate service conditions on an accelerated basis.
Penetration or Penetration Number – A measure of the hardness and consistency of bitumen and lubricating greases in terms of the distance in tenths of a millimetre by which a weighted special needle or cone will penetrate the sample in five seconds, the temperature, unless otherwise stated being 25°C. The softer the consistency, the higher the penetration number.
Pour Point – The pour point of a lubricant is the lowest temperature at which the lubricant will pour or flow when it is chilled without disturbance under specified conditions.
Saponification – The chemical conversion of a fatty acid and base or alkali into a soap. A common process in grease manufacture.
Shear Stability – The ability of a grease or lubricating oil to withstand mechanical shearing without being degraded in consistency or viscosity.
Slumpability – A property of some greases that makes them partially self levelling. Greases possessing this property can be pumped from a container
without the need for a follower plate.
Smoke Point – The maximum height of flame measured in millimetres at which a kerosine will burn without smoking when tested in a standard lamp.
Soap – A compound formed in the reaction between a metal hydroxide (such as lime) and a fatty acid (an organic acid derived from natural fats), e.g. lithium, calcium soaps in grease. The ordinary soaps are those of sodium and potassium. The soaps of lithium, calcium, sodium, and aluminium are the principal thickeners used in grease making.
Solid Lubricant – Any class of lubricants in which the reduction of friction and wear during sliding is caused by making the shearing take place within the crystal structure of a material with low shear strength in one particular plane. Examples include graphite, molybdenum disulphide, and certain soaps. Lubricating grease is not a solid lubricant, but may contain solid lubricants as additives.
Static Friction – The friction between two surfaces not in relative motion but tending to slide over one another. The value of the static friction at the instant relative motion begins is termed breakaway friction.
Thermal Conductivity – Measure of the ability of a solid or liquid to transfer heat.
Thermal Stability – The ability of a substance to resist degradation due to the effects of heat. The same as hydrodynamic lubrication.
Total Acid Number (TAN) – The quantity of base, expressed in terms of the equivalent number of milligrams of potassium hydroxide, that is required to titrate the strong base constituents present in 1 gram of sample. A measurement of TAN can give an indication of the deterioration of an oil in service due to oxidation.
Total Base Number (TBN) – The quantity of base, expressed in terms of the equivalent number of milligrams of potassium hydroxide, that is required to titrate the strong
base constituents present in 1 gram of sample.
Toxicity – The capacity of a substance to harm living organisms.
Universal Farm Oil – A lubricant for agricultural tractors and farm machinery which is able simultaneously to carry out the functions of an engine oil, transmission oil and hydraulic oil.
Viscosity – The property of a fluid or semi-solid substance to resist flow and defined as the ratio of the shear stress to the rate of shear of a fluid element. The standard unit of viscosity in the c.g.s. system is the poise and is expressed in dyne sec. per square centimetre. A number, usually between 0 and 200, which is a measure of a fluid’s change of viscosity with temperature. The higher the viscosity index the smaller the change in viscosity with temperature.
W – When used in the SAE system for classifying oils, an indication that the oil is suitable for winter use.
Water Resistance – The ability of a lubricant to withstand the addition of water to the lubricant system without adverse effects.
Water Separability – The ability of a lubricating oil to shed any water with which it has become intimately mixed.
Jenis komponen mesin:
Crosshead – A shaft that connects the piston to the connecting rod in double-acting reciprocating compressors and in certain types of piston engine.
Follower Plate – A metal sheet used on top of the grease in a pump-type dispenser to assure the grease remains level as it is pumped. This avoids the formation of a cavity around the pump pick-up tube and enables all the grease to be dispensed without manual levelling from time to time.
Gas Turbine – A rotary engine with a driving shaft that is fitted with vanes that are rotated by the pressure of gas passing over them.
Grease Cup – A device for supplying grease to a component from a reservoir attached to the component requiring lubrication.
Helical Gear – A pair of gear wheels used to transmit motion between parallel shafts. The teeth of a helical gear wheel are cut on an angle to its axis.
Herringbone Gear – The same as a double helical gear.
High Speed Diesel Engine – A diesel engine, like that used to power road transport vehicles, which operates at speeds of 1,250 rpm or more.
Hypoid Gear – A system of gears for transmitting motion at an angle in which the axis of the pinion does not intersect the axis of the main gear wheel.
Low Speed Diesel Engine – A diesel engine, like that used to power marine transport, which operates at speeds of less than 350 rpm.
Medium Speed Diesel Engine – A diesel engine, like that used for electricity generation, which operates at speeds between 350 and 1,250 rpm.
Multi-stage Compressor – A machine which essentially consists of several linked compressors, one feeding compressed gas to the next for further compression.
Pensky-Martens Closed Cup (PMCC) – The apparatus for determining the closed flash point of fuel oils. Lubricating oils and other petroleum products.
Pinion – The smaller gear wheel of a pair.
Piston Pump – A type of pump used in hydraulic systems which pumps fluid by means of reciprocating pistons moving in cylinders.
Plain Bearing – The simplest kind of bearing which consists of two flat surfaces moving relative to one another, distinguished from tapered land, tilting pad, or anti-friction bearings.
Rack and Pinion – A gear system used for converting rotary motion into linear motion or vice versa. It consists of a toothed bar (the rack) which meshes with a toothed wheel (the pinion).
Reciprocating Compressor – A machine which compresses gases by the action of a piston moving in a cylinder.
Redwood Viscometer – Standard British viscometer. The number of seconds required for 50 ml of an oil to flow out of a standard Redwood viscometer at the definite temperature (IP Method 70). Instrument is available in two sizes: Redwood No. 1 and No. II. When the flow time exceeds 2,000 sec, the No. II must be used.
Rocker Arm – A lever which is operated automatically to open and close the valves of an internal combustion engine.
Rolling Bearing – A general term describing all types of ball and roller bearings.
Rotary Compressor – A machine in which gas compression is achieved by the revolution of a rotor or rotors.
Rotary Screw Compressor – A machine which compresses air by the action of two intermeshing screws or rotors.
Rotary Vane Compressor – A machine which compresses air through the action of sliding vanes set in slots in a rotor which turns in a cylindrical casing.
SAE EP Lubricant Tester – A machine designed to test the extreme pressure properties of a lubricant under a combine rolling and sliding action. The revolving members are two bearing cups that rotate at different speeds.
Screw Pump – A pump used in some hydraulic systems which pumps fluid through the action of intermeshing screws.
Self-aligning Bearing – A rolling bearing in which the applied load is distributed uniformly within the bearing even when the alignment of the shaft changes.
Separator – In rolling bearings, the same as a cage. In compressed air systems, the same as a coalescer.
Single-acting Compressor – A reciprocating compressor with cylinders that contain only one compression chamber.
Single-stage Compressor – A machine which takes in a gas and compresses it fully in one action.
Sliding Bearing – A bearing which supports a load and allows it to slide.
Sliding Vane Compressor – The same as a rotary vane compressor.
Spur Gear – A pair of toothed wheels used to transmit power between parallel shafts. The teeth of a spur gear wheel are cut parallel to its axis.
Sump – The lower section of the crankshaft housing used as a lubricating reservoir in an internal combustion engine.
Super-charger – A device which is able to supply air to an internal combustion engine at a higher-than-normal pressure.
Tapered Roller Bearing – A rolling bearing which is suitable for carrying both radial and thrust loads because its rolling elements are cone-shaped.
Transmission – The assembly of parts, including the clutch, gearbox and propeller shaft, by which power is transmitted from an engine of a motor vehicle to the wheels.
Trunk Piston Engine – An internal combustion engine in which the piston is connected directly to the connecting rod and subsequently to the crankshaft.
Turbo charger – A compressor device driven by an exhaust gas turbine that is used to supply air at a higher-than-normal pressure to the cylinders of an internal combustion engine.
Worm Gear – A gear consisting of a toothed wheel and a short revolving screw working together.