Grease Lubrication in Rolling Bearings

Lugt, Piet M.

doi:10.1002/9781118483961

Cited by 180 publications

(210 citation statements)

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“…These properties make grease particularly suitable for application in rolling bearings. Indeed, this is by far the most common application of lubricating greases, with more than 90% of rolling bearings employing grease as the lubricant [1]. Rolling bearings are ubiquitous machine elements used in almost all engineering systems, and across many different sectors of industry and transportation.…”

Section: Introductionmentioning

confidence: 99%

“…Rolling bearings are ubiquitous machine elements used in almost all engineering systems, and across many different sectors of industry and transportation. It is reported that over 50 billion bearings are operating in the world at any time [1]. As a result, the cumulative impact of bearing frictional losses on the energy efficiency and sustainability of mechanical systems is significant.…”

Section: Introductionmentioning

confidence: 99%

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The Influence of Base Oil Properties on the Friction Behaviour of Lithium Greases in Rolling/Sliding Concentrated Contacts

et al. 2017

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This study investigates the influence of base oil type and viscosity on the frictional behaviour of lithiumthickened bearing greases. A series of model lithium greases were manufactured by systematically varying viscosity and type of base oil, so that the influence of a single base oil property could be studied in isolation. In addition, selected greases were blended with oleic acid, with the purpose of evaluating its effectiveness in further reducing grease friction. Friction coefficient and film thickness were measured in laboratory ball-on-disc tribometers over a range of speeds and temperatures. For a specific oil type, the influence of base oil viscosity on friction was found to be closely related to its effect on film thickness: greases formulated with PAO oils covering a wide range of viscosities gave very similar friction at the same nominal film thickness. For a given base oil viscosity, base oil type was found to have a strong influence on grease friction under all test conditions. PAO-based greases generally produced lower friction than mineral-and ester-based greases. Addition of oleic acid to the test greases did not significantly affect friction within the range of test conditions employed in this study. The results provide new insight into the frictional behaviour of greases, which may be used to help inform new low-friction grease formulations for rolling bearing applications.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Influence of Base Oil Properties on the Friction Behaviour of Lithium Greases in Rolling/Sliding Concentrated Contacts

et al. 2017

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“…In general, grease fluidity is highly dependent on the temperature as the grease viscosity is dependent on the temperature; see e.g. Lugt [22]. The lower the temperature is, the more difficult it is to reach correct lubrication and a higher pressure is required.…”

Section: Manometer (A) (B)mentioning

confidence: 99%

“…The grease yield behaviour generally increases with the NLGI grade, but the yield stress for a given grease also varies with temperature such that the yield stress value increase with a decreasing temperature -and vice versa decrease with increasing temperature [22], [26], which also is the case for the grease viscosity. This means that for a sufficiently low temperature the yield stress is so large that the grease is unable to flow with the shear rates induced through the applied pressure by the grease pump.…”

Section: Grease Flow Testmentioning

confidence: 99%

New method for lubricating wind turbine pitch gears using embedded micro-nozzles

2017

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Aquesta és una còpia de la versió author's final draft d'un article publicat a la revista Journal of mechanical science and technology.La publicació final està disponible a Springer a través de http://dx.doi.org/10.1007/s12206-017-0131-3 This is a copy of the author 's final draft version of an article published in the journal Journal of mechanical science and technology. --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- AbstractThe increase of power generated by wind turbines has increased the stresses applied in all of its parts, which causes the appearance of premature failures. In particular, pitch and yaw gears suffer of excessive wear, mainly due to inappropriate lubrication. This paper presents a novel method to automatically lubricate the wind turbine pitch gear during operation. A micro-nozzle to continuously inject fresh grease between the teeth in contact was designed, manufactured and installed in a test bench of a 2 MW wind turbine pitch system. The test bench was used to characterize the fatigue behavior of the gear surface using conventional wind turbine greases under real cyclic loads. The measurements of wear evolution in a pitch gear with and without micro-nozzle show a decrease of 70% of the wear coefficient after 2x10 4 cycles.

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“…Grease generates a higher film thickness than its base oil under fully flooded conditions [1][2][3], because of the presence of a thickener. However, in most cases, a bearing functions under the starvation phase [4]. During this phase, most of the grease is pushed aside the rolling track, leaving only a small amount of grease to lubricate contact.…”

Section: Introductionmentioning

confidence: 99%

Effects of nano thickener deposited film on the behaviour of starvation and replenishment of lubricating greases

et al. 2016

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Abstract:The mechanism of grease replenishment in and around a starved point contact was studied in this work. Greases made of different thickeners and same base oil were tested and compared. Disappearing and re-formation of a dynamic grease reservoir during operation revealed that grease bled oil to replenish contact. However, the replenishment process was slow because of the presence of grease fingers along the track and thickener-deposited film inside the track. The contact angles of base oil on the chromium-coated surface and thickener-deposited surfaces were measured. Results proved that the contact angle on the deposited film remarkably increased compared with that on the chromium-coated surface from 25° to more than 40°. However, the deposited film could be consumed with continuous rolling, and replenishment was then enhanced.

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Grease Lubrication in Rolling Bearings

Cited by 180 publications

References 0 publications

The Influence of Base Oil Properties on the Friction Behaviour of Lithium Greases in Rolling/Sliding Concentrated Contacts

The Influence of Base Oil Properties on the Friction Behaviour of Lithium Greases in Rolling/Sliding Concentrated Contacts

New method for lubricating wind turbine pitch gears using embedded micro-nozzles

Effects of nano thickener deposited film on the behaviour of starvation and replenishment of lubricating greases

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