An Experimental Investigation of Grease-Lubricated Journal Bearings

Lu, Xiaobin; Khonsari, M. M.

doi:10.1115/1.2401216

Cited by 16 publications

(4 citation statements)

References 29 publications

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“…the friction coefficient decreases with the normal load. This is not the expected normal force influence in the boundary and mixed lubrication regimes [54] but it is consistent with the higher rheological resistance offered by the grease to the rotational motion at lower normal loads [28].…”

Section: Evolution Of Friction Coefficient With Timesupporting

confidence: 64%

“…However, this approach is not widely reported for lubricating greases as a consequence of the non-Newtonian character and the unknown properties of the active lubricant inside the contact [16]. Lu and Khonsari [54] and Gonçalves et al [55] proposed the inclusion of the viscosity of the base oil, assuming that under highly stressed conditions, like those achieved in a tribological contact, the microstructure of the grease is almost destroyed and the main responsible for lubrication is the base oil:…”

Section: Evolution Of the Friction Coefficient With The Sliding Velocitymentioning

confidence: 99%

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Tribological behaviour of novel chemically modified biopolymer-thickened lubricating greases investigated in a steel–steel rotating ball-on-three plates tribology cell

Gallego

Cidade

Sánchez

et al. 2016

Tribology International

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In this work, model renewable and biodegradable lubricating greases based on castor oil and chemically modified biopolymers (methylcellulose, chitin and cellulosic pulp) were tribologically characterized in a steel–steel ball-on-plates tribological cell coupled to a controlled-stress rheometer, and the results were compared to those provided by conventional lithium and calcium soap-based greases. Viscous flow, sliding velocity sweep and transient friction tests were carried out and resulting wear scars in the steel plates were evaluated by means of scanning electron microscopy (SEM). Different frictional responses were found depending on the thickener, especially at high temperature. Excepting for most severe conditions, wear is negligible when using chemically modified chitin and methylcellulose-based greases as lubricants.This work is part of two research projects (CTQ2014-56038-C3-1R and TEP-1499) sponsored by MINECO-FEDER and Junta de Andalucia programmes, respectively. One of the authors (Rocio Gallego) has received a Ph.D. Research Grant (BES-2011-045029) from DIGICyT (MINECO). The authors gratefully acknowledge the financial support. Maria Teresa Cidade acknowledges the support of the Portuguese Foundation for Science and Technology through Project PEst-C/CTM/LA0025/2013 and The Portuguese Society of Rheology (SPR) for her stay in University of Huelva

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Section: Evolution Of Friction Coefficient With Timesupporting

confidence: 64%

Section: Evolution Of the Friction Coefficient With The Sliding Velocitymentioning

confidence: 99%

Tribological behaviour of novel chemically modified biopolymer-thickened lubricating greases investigated in a steel–steel rotating ball-on-three plates tribology cell

Gallego

Cidade

Sánchez

et al. 2016

Tribology International

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“…Amann et al [18] investigate galvanically coupled journal bearings to minimise friction and determine that by coupling water with complex fluids, a significant reduction in friction and wear can be achieved compared to conventional oil lubrication. Lu and Khonsari [19] carry out tribometer tests on oil-and grease-lubricated journal bearings and conclude that grease is better suited for highly loaded journal bearings in the area of boundary and mixed friction than in liquid friction, as it has a lower coefficient of friction here compared to oil.…”

Section: State Of Artmentioning

confidence: 99%

Application Limits of small dimensioned Sintered Journal Bearings in Grease-lubricated Planetary Gears

Huber,

Monz

2023

Proceedings of the 9th World Congress on Mechanical, Chemical, and Material Engineering

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The design of machine elements as sintered components offers further potential in addition to economic advantages in production and technical innovations, such as the use of self-lubricating components. As a result, sintered planetary gears are now being used in planetary gear units, with a journal bearing bushing integrated in the bore. In this context, it is necessary both to consider the material requirements in the joint material selection and to optimally resolve controversial design variables of both, the gear and the journal bearing, such as the gear width and the journal bearing width. On the occasion of this trend in development, the present research work deals with the application limits of sintered planetary journal bearings under grease lubrication. In the field of drive technology, it can be observed that these cannot be designed reliably according to the usual design guidelines, such as DIN 31652 1-4, VDI 2204 1-4 or ISO 7902 1-3 for conventional journal bearings. The result is failure of the bearing due to seizure and wear. Therefore, the decisive parameters need to be determined and further analysed. Due to the mutual influence on the operating performance of journal bearing and gearing and the resulting large number of parameters sets, it is not promising to systematically optimize the journal bearing system in gearbox tests. Therefore, the influence of the planetary gear is first abstracted. On a test bench specially developed for this application, the operating behaviour of a journal bearing bushing rotating around a stationary shaft is mapped and tested analogously to the operating conditions in a planetary gear. In the project, characteristic diagrams are thus generated for the characterization of sintered journal bearings. The results obtained by varying the parameter sets are presented and discussed.

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“…Additionally, it is known that the grease properties might change drastically in the very beginning of its life [1]. The lack of consensus on how grease lubricates the contact and the uncertainty about the rheological properties of the lubricant film along the grease's life [14,15] lead most of the research efforts to understand the grease film composition and formation.…”

Section: Introductionmentioning

confidence: 99%

Grease Aging Effects on Film Formation under Fully-Flooded and Starved Lubrication

Cousseau

Graça

Campos³

et al. 2015

Lubricants

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Several film thickness measurements were performed with three fresh and aged lubricating greases, their base and bled oils under a wide range of operating conditions using a ball-on-disc test rig with optical interferometry. The analysis of the film thickness measurements is in agreement with the observations of several authors and adds some important aspects regarding separate film properties in EHL contacts. At full film lubrication and moderate to high speeds, the bled oil showed a similar behavior of its lubricating greases. At fully-flooded condition, low speeds and thin films, it was observed that the thickener lumps play a major role on film formation, overcoming the bled oil effects. A relationship between thickener type and film formation was evidenced. The same trends were observed under starved lubrication, where the thickener type that contributes the most to locally increase the film thickness follows the order of PP > Ca > Li. The aging process of the greases was shown to change their rheological response in different manners-softening or hardening-depending on the grease formulation. Grease aging increased the film thickness under fully-flooded and starved lubrication, regardless of the level of degradation.

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An Experimental Investigation of Grease-Lubricated Journal Bearings

Cited by 16 publications

References 29 publications

Tribological behaviour of novel chemically modified biopolymer-thickened lubricating greases investigated in a steel–steel rotating ball-on-three plates tribology cell

Tribological behaviour of novel chemically modified biopolymer-thickened lubricating greases investigated in a steel–steel rotating ball-on-three plates tribology cell

Application Limits of small dimensioned Sintered Journal Bearings in Grease-lubricated Planetary Gears

Grease Aging Effects on Film Formation under Fully-Flooded and Starved Lubrication

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