Allowable Surface Durability in Grease Lubricated Gears

Fukunaga, Keigo

doi:10.1080/10402008808981848

Cited by 13 publications

(5 citation statements)

References 7 publications

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“…The surrounding grease expands and softens when the temperature in the contact zone increases, and more grease smears onto the interacting surfaces, consequently stabilizing the lubrication film. It confirms the investigation of lubricating film thickness during the grease operation (Lansdown, 2004;Fukunaga, 1988). This mechanism could be more efficient if the tribological additives in greases are interacting with the lubricating material and the thickener.…”

Section: Discussionsupporting

confidence: 81%

Lubrication properties of modified lard and rapeseed oil greases with sodium and lithium thickeners

Padgurskas

Rukuiža

Kupčinskas

et al. 2015

Industrial Lubrication and Tribology

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Purpose-The purpose of this paper is to conduct research on the possibility of improving the tribological and utilization properties of lard and rapeseed oil bio-based greases by mixing it with ethanol and selection of thickener and modification with special biological additives. Design/methodology/approach-Rapeseed oil-and lard-based greases with sodium and lithium soap thickeners were mixed with either water or ethanol and modified with a special biological anti-wear additive. Tribological properties of modified lubricants evaluated on a four-ball machine. Findings-Rapeseed oil-and lard-based greases suspended in ethanol and modified with bio-additive have the same wear resistance as the industrial non-biological lubrication grease and much higher wear resistance as bio-based reference grease. The tribological efficiency of the additives is higher in greases of rapeseed oil and less efficient in lard-based greases. Oxidation and wear tests show that investigated bio-based greases have comparatively stable tribological properties also after their aging. Modified greases have sufficient consistence according penetration measurements and high thermal resistance according drop-point temperature measurements. All produced experimental greases pass within the category of the easily degradable materials. Originality/value-The greases mixed with the ethanol make possible to form more homogeneous and stable grease mixture. Modified bio-based greases have significantly higher wear resistance as bio-based reference grease, their lubrication properties are stable also after the aging and are categorized as easily degradable materials.

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Section: Discussionsupporting

confidence: 81%

Lubrication properties of modified lard and rapeseed oil greases with sodium and lithium thickeners

Padgurskas

Rukuiža

Kupčinskas

et al. 2015

Industrial Lubrication and Tribology

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“…Greases with NLGI 1 show more availability on the tooth flanks at a sump temperature of 90 °C compared with 60 °C, thus supporting the circulating lubrication mechanism. Stemplinger [19], Fukuna [17] and Hochmann [18] proved a strong influence of the grease fill level on the lubrication mechanisms "circulating" and "channeling". Stemplinger [19] performed experiments on a FZG back-to-back test rig, where a fill level of 54 % corresponds to the middle of the axes of pinion and wheel.…”

Section: Grease Lubrication In Gearboxesmentioning

confidence: 99%

“…The thickener can also influence the lubrication mechanism. Fukunaga [17] states that the consistency is more important than the base oil viscosity. He shows that lithium-and aluminumcomplex soap thickeners have the best phase separation, which is advantageous for both channeling and circulating.…”

Section: Grease Lubrication In Gearboxesmentioning

confidence: 99%

WITHDRAWN: Numerical Visualization of Grease Flow in a Gearbox

Liu¹,

Dangl²,

Lohner³

et al. 2020

Preprint

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Gearbox lubrication plays a decisive role in both load capacity and efficiency. It is necessary for the formation of a lubricant film in tribological contacts, and for heat dissipation. Grease lubrication is often applied to gearboxes at a low operating speed and means that, for example, less effort is required in sealing design compared to oil lubrication. Over the years, the computational fluid dynamics (CFD) method has frequently been applied to support the lubrication-related design of gearboxes. However, very few studies have focused on grease lubrication. Whereas oil can generally be considered as Newtonian fluid, grease displays complex non-Newtonian flow behavior. In this study, the grease lubrication of a single-stage test gearbox is investigated by means of a finite-volume based CFD model. The numerical results on the grease flow show good accordance with high-speed camera recordings, and clearly display the lubrication mechanisms of “channeling” and “circulating”. These first results on grease flow simulation in gearboxes offer a starting point for further numerical studies.

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“…The thickener also influences the lubrication mechanism. Fukunaga [20] states that the consistency is more important than the base oil viscosity. He shows that lithium-and aluminum-complex soap thickeners have the best phase separation, which is advantageous for oil separation from the grease and hence for both channeling and circulating.…”

Section: Grease Lubrication In Gearboxesmentioning

confidence: 99%

Numerical Visualization of Grease Flow in a Gearbox

Liu

Dangl

Lohner

et al. 2023

Chin. J. Mech. Eng.

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Lubricating greases are widely used in e.g. open gear drives and gearboxes with difficult sealing conditions. The efficiency and heat balance of grease-lubricated gearboxes depend strongly on the lubrication mechanisms channeling and circulating, for which the grease flow is causal. The computational fluid dynamics opens up the possibility to visualize and understand the grease flow in gearboxes in more detail. In this study, a single-stage gearbox lubricated with an NLGI 1-2 grease was modeled by the finite-volume method to numerically investigate the fluid flow. Results show that the rotating gears influence the grease sump only locally around the gears. For a low grease fill volume, the rotation of the gears is widely separated from the grease sump. For a high grease fill volume, a pronounced gear-grease interaction results in a circulating grease flow around the gears. The simulated grease distributions show good accordance with high-speed camera recordings.

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Allowable Surface Durability in Grease Lubricated Gears

Cited by 13 publications

References 7 publications

Lubrication properties of modified lard and rapeseed oil greases with sodium and lithium thickeners

Lubrication properties of modified lard and rapeseed oil greases with sodium and lithium thickeners

WITHDRAWN: Numerical Visualization of Grease Flow in a Gearbox

Numerical Visualization of Grease Flow in a Gearbox

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