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A lubricant is a substance that helps to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces, transporting foreign particles, or heating or cooling the surfaces. The property of reducing friction is known as lubricity.
A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.
Motor oil, engine oil, or engine lubricant is any one of various substances used for the lubrication of internal combustion engines. They typically consist of base oils enhanced with various additives, particularly antiwear additives, detergents, dispersants, and, for multi-grade oils, viscosity index improvers. The main function of motor oil is to reduce friction and wear on moving parts and to clean the engine from sludge and varnish (detergents). It also neutralizes acids that originate from fuel and from oxidation of the lubricant (detergents), improves the sealing of piston rings, and cools the engine by carrying heat away from moving parts.
A bearing is a machine element that constrains relative motion to only the desired motion and reduces friction between moving parts. The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts. Most bearings facilitate the desired motion by minimizing friction. Bearings are classified broadly according to the type of operation, the motions allowed, or the directions of the loads (forces) applied to the parts.
Tribology is the science and engineering of understanding friction, lubrication and wear phenomena for interacting surfaces in relative motion. It is highly interdisciplinary, drawing on many academic fields, including physics, chemistry, materials science, mathematics, biology and engineering. The fundamental objects of study in tribology are tribosystems, which are physical systems of contacting surfaces. Subfields of tribology include biotribology, nanotribology and space tribology. It is also related to other areas such as the coupling of corrosion and tribology in tribocorrosion and the contact mechanics of how surfaces in contact deform. Approximately 20% of the total energy expenditure of the world is due to the impact of friction and wear in the transportation, manufacturing, power generation, and residential sectors.
Synthetic oil is a lubricant consisting of chemical compounds that are artificially modified or synthesised. Synthetic lubricants can be manufactured using chemically modified petroleum components rather than whole crude oil, but can also be synthesized from other raw materials. The base material, however, is still overwhelmingly crude oil that is distilled and then modified physically and chemically. The actual synthesis process and composition of additives is generally a commercial trade secret and will vary among producers.
A plain bearing, or more commonly sliding contact bearing and slide bearing, is the simplest type of bearing, comprising just a bearing surface and no rolling elements. Therefore, the journal slides over the bearing surface. The simplest example of a plain bearing is a shaft rotating in a hole. A simple linear bearing can be a pair of flat surfaces designed to allow motion; e.g., a drawer and the slides it rests on or the ways on the bed of a lathe.
The National Lubricating Grease Institute is an international trade association that serves the grease and gear lubricant industry. It exists to promote research and development of lubrication technology. It also publishes industry standards for greases.
The NLGI consistency number expresses a measure of the relative hardness of a grease used for lubrication, as specified by the standard classification of lubricating grease established by the National Lubricating Grease Institute (NLGI). Reproduced in standards ASTM D4950(“standard classification and specification of automotive service greases”) and SAE J310(“automotive lubricating greases”), NLGI's classification is widely used. The NLGI consistency number is also a component of the code specified in standard ISO 6743-9“lubricants, industrial oils and related products — classification — part 9: family X (greases)”.
The dropping point of a lubricating grease is an indication of the heat resistance of the grease and is the temperature at which it passes from a semi-solid to a liquid state under specific test conditions. It is dependent on the type of thickener used and the cohesiveness of the oil and thickener of a grease. The dropping point indicates the upper temperature limit at which a grease retains its structure though is not necessarily the maximum temperature at which a grease can be used.
Gear oil is a lubricant made specifically for transmissions, transfer cases, and differentials in automobiles, trucks, and other machinery. It has high viscosity and usually contains organosulfur compounds. Some modern automatic transaxles do not use a heavy oil at all but lubricate with the lower viscosity hydraulic fluid, which is available at pressure within the automatic transmission. Gear oils account for about 20% of the lubricant market.
False brinelling is a bearing damage caused by fretting, with or without corrosion, that causes imprints that look similar to brinelling, but are caused by a different mechanism. False brinelling may occur in bearings which act under small oscillations or vibrations.
Grease is a solid or semisolid lubricant formed as a dispersion of thickening agents in a liquid lubricant. Grease generally consists of a soap emulsified with mineral or vegetable oil.
AW additives, or antiwear additives, are additives for lubricants to prevent metal-to-metal contact between parts of gears.
Extreme pressure additives, or EP additives, are additives for lubricants with a role to decrease wear of the parts of the gears exposed to very high pressures. They are also added to cutting fluids for machining of metals.
Oil additives are chemical compounds that improve the lubricant performance of base oil. The manufacturer of many different oils can utilize the same base stock for each formulation and can choose different additives for each specific application. Additives comprise up to 5% by weight of some oils.
Dry lubricants or solid lubricants are materials that, despite being in the solid phase, are able to reduce friction between two surfaces sliding against each other without the need for a liquid oil medium.
A dead weight tester apparatus uses unknown traceable weights to apply pressure to a fluid for checking the accuracy of readings from a pressure gauge. A dead weight tester (DWT) is a calibration standard method that uses a piston cylinder on which a load is placed to make an equilibrium with an applied pressure underneath the piston. Deadweight testers are so called primary standards which means that the pressure measured by a deadweight tester is defined through other quantities: length, mass and time. Typically deadweight testers are used in calibration laboratories to calibrate pressure transfer standards like electronic pressure measuring devices.
Base Number (BN) is a measurement of basicity that is expressed in terms of the number of milligrams of potassium hydroxide per gram of oil sample. BN is an important measurement in petroleum products, and the value varies depending on its application. BN generally ranges from 6–8 mg KOH/g in modern lubricants, 7–10 mg KOH/g for general internal combustion engine use and 10–15 mg KOH/g for diesel engine operations. BN is typically higher for marine grade lubricants, approximately 15-80 mg KOH/g, as the higher BN values are designed to increase the operating period under harsh operating conditions, before the lubricant requires replacement.
SAE J300 is a standard that defines the viscometric properties of mono- and multigrade engine oils, maintained by SAE International. Key parameters for engine oil viscometrics are the oil's kinematic viscosity, its high temperature-high shear viscosity measured by the tapered bearing simulator, and low temperature properties measured by the cold-cranking simulator and mini-rotary viscometer. This standard is commonly used throughout the world, and standards organizations that do so include API and ILSAC, and ACEA.
References
- 1 2 3 "Lubrication: Frequently Asked Questions". Timken. Archived from the original on 2015-07-25. Retrieved 2015-07-24.