Applied Tribology: Bearing Design and Lubrication

Khonsari, M. M.; Booser, E. Richard

doi:10.1002/9781118700280

Cited by 185 publications

(189 citation statements)

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“…The hash-marked area is the bearing sleeve and within it, a shaft (journal) is rotating with a load, W acting down on it. The rotating motion of the shaft entrains the lubricant between the shaft and bearing, thus producing a pumping action, which lifts the shaft in an eccentric position, e, relative to the bearing's centerline, hence, producing an oil film [19]. In this lubrication mode, the surfaces will never come into contact except perhaps as a result of sudden angular accelerations which may cause the film to fail [20] [2].…”

Section: Lubrication Modes Encountered In Machinerymentioning

confidence: 99%

“…These are more accurately known as Hertzian contacts which require knowledge of contact-mechanics for a proper evaluation [10]. The pressures within these lubricated contacts are in the 0.5 − 3 GPa range of magnitude [19]. The stresses developed therein exceed the yield stress of the material just below the surface and inevitably, spalling wear [21] ensues.…”

Section: Lubrication Modes Encountered In Machinerymentioning

confidence: 99%

“…Increasing the fluid's temperature will reduce its viscosity while decreasing the temperature will do the opposite. If the pressure in the oil is brought high enough a phase change to a solid can occur [19]. Although, in practice such pressure is not reached, an increase will cause a rise in viscosity just as lowering the temperature does.…”

Section: Lubricating Oil Viscositymentioning

confidence: 99%

“…These long chain, high molecular weight hydrocarbon molecules are additives used in lubrication to lower the viscosity drop of a lubricant at higher temperatures. VII containing lubricants have been shown to exhibit shear-thinning [19] behavior in turbines where the oil sustained shear rates in excess of 10 6 s −1 . They have also been reported to show non-Newtonian behaviour [14] as they degrade over time.…”

Section: Lubricating Oil Viscositymentioning

confidence: 99%

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The Development of a Diesel Injector Experiment to Study the Combined Effects of Oxidation and Shear on Lubricating Oil Viscosity

Laforge¹

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An experimental test rig was needed to apply high rates of shear strain on lubricating oil molecules and study the effects these may have on the degradation of the lubricant.The result was the development of a diesel injector experiment where the degraded oil from a bench-top oxidation apparatus could be stressed and cycled effectively.Viscosity measurements were used to determine whether or not the oil had degraded.A change in viscosity in high molecular weight compounds is evidence of chain scission.The results show that cycling a 128 ml volume of oil 12 times has no effect on fresh, unaltered lubricating oils, even at low oxidation times up until 48 hours. However, the results show that heavily degraded lubricating oils near and beyond their usability limit, do exhibit a viscosity loss of up to 19%.iii

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Section: Lubrication Modes Encountered In Machinerymentioning

confidence: 99%

Section: Lubrication Modes Encountered In Machinerymentioning

confidence: 99%

Section: Lubricating Oil Viscositymentioning

confidence: 99%

Section: Lubricating Oil Viscositymentioning

confidence: 99%

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The Development of a Diesel Injector Experiment to Study the Combined Effects of Oxidation and Shear on Lubricating Oil Viscosity

Laforge¹

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“…Where the decrease in lubricant viscosity across a range of temperatures is too great, or the base oil viscosity is too low to provide adequate film thickness at a specific temperature, viscosity index improvers (VIIs) may be added to a formulated lubricant to increase and stabilize the lubricant viscosity across a range of temperatures as shown in Figure 2.11. Viscosity index additives typically consist of high molecular weight oil-soluble polymers (on the order of 10'000 -100'000 g/mol [41]) which are dissolved in the base oil to increase the viscosity index [5]. Viscosity index additives are commonly blended with a base oil in weight-percent concentrations from 0.8 % to 2% [7].…”

Section: Viscosity Additivesmentioning

confidence: 99%

Shear Stability of Vegetable Oil-Based Lubricants with Ethyl Cellulose Viscosity Index Improver

McCallum¹

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A diesel fuel injector apparatus conforming to ASTM 6278 was used to examine the effects of mechanical shear on two vegetable oil-base lubricants, each blended with a different molecular weight ethyl cellulose polymer to improve its viscosity-temperature behaviour. Kinematic viscosity measurements conforming to ASTM D445 were used to determine the magnitude of viscosity loss after mechanical shearing. The lower molecular weight E45 sample was determined to have a permanent viscosity loss of 0.73% and a shear stability index of 1.56, whereas the higher molecular weight EC100 sample was determined to have a permanent viscosity loss of 3.57% and a shear stability index of 6.51. Results were comparable to traditional PMMA polymer additives of similar molecular weight which are commonly used in petroleum-based lubricants, indicating that the ethyl cellulose polymers may function well as VIIs even after mechanical shear degradation. Kinematic viscosity measurements of increasingly dilute solutions of prepared lubricants were used to determine the changes in the intrinsic viscosity of solution as an indicator of the decrease in polymer molecular weight after shearing.ii

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Friction, Lubrication, and Wear

Butt

Graf

Kappl

2003

Physics and Chemistry of Interfaces

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Friction is the force between interacting surfaces that resists or hinders their relative movement. Wear is defined as the progressive loss of material from a body caused by contact and relative movement of a contacting solid, liquid or gas. The aim of lubrication is to reduce friction between surfaces and minimize wear. Today the research field of friction, lubrication and wear is called "tribology". This word is derived from the ancient Greek word "tribein" (meaning rubbing) and was first used in 1966 in a publication titled, The Jost Report: Lubrication (Tribology) Education and Research published by Her Majesty's Stationery Office (HMSO) in the United Kingdom. Since then it became the common term to describe the science of friction, wear, and lubrication. Introductions to this field are Refs. [452, 453].In spite of the strong economic importance of friction and wear and the resulting scientific effort, our understanding of the fundamental processes is still rudimentary. This results from the complexity of these topics. In addition, this complexity demands a multi-disciplinary approach to tribology. In recent years the development of new experimental methods such as the surface forces apparatus, the atomic force microscope, and the quartz microbalance made it possible to study friction and lubrication at the molecular scale. However, this new wealth of information does not alter the fact, that there are no fundamental equations to describe wear or calculate friction coefficients. Engineers still have to rely largely on their empirical knowledge and their extensive experience.

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Applied Tribology: Bearing Design and Lubrication

Cited by 185 publications

References 0 publications

The Development of a Diesel Injector Experiment to Study the Combined Effects of Oxidation and Shear on Lubricating Oil Viscosity

The Development of a Diesel Injector Experiment to Study the Combined Effects of Oxidation and Shear on Lubricating Oil Viscosity

Shear Stability of Vegetable Oil-Based Lubricants with Ethyl Cellulose Viscosity Index Improver

Friction, Lubrication, and Wear

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