Related papers
Rolling Bearing Damages
Georg Jacobs
Encyclopedia of Lubricants and Lubrication, 2014
Hydraulic sealing systems; Reciprocating seals Definition Nowadays, the sealings of hydraulic cylinders are predominantly implemented by means of sealing systems. Piston and rod seals, guides, and wipers are finely matched components which ensure not only the pressure buildup, but primarily prevent leakages on a sustained basis. The developments in the areas of materials and geometries, a significantly improved understanding of systems, as well as modern simulation possibilities permit maximum performance levels of hydraulic cylinders, commensurate with the respective function: 800 bar, no stick-slip, zero-leakage, or temperatures depending on the material from-50 C to +200 C are feasible with modern sealing systems.
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Grease Lubrication Mechanisms in Bearing Seals
P. Lugt
Lugt/Grease, 2012
Below is a list of papers which are included in the thesis.
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An Experimental and Numerical Evaluation of Seal Strictness on Ball Bearing Performance
Zafer özdemir
Hittite Journal of Science & Engineering, 2021
T he basic working principle of a ball bearing is to reduce the friction force to a minimum and to make load transfer between two relative rotating mechanisms. The ball bearings are used among a variety of mechanisms such as shaft, axis, pumps, heavy load machines, wind turbines, and machine tools [1]. The friction force produced by ball bearings determines the heat amount produced. Friction force arises from the loads applied to ball-bearing, type and size of ball-bearing, operating cycle, lubricant properties. The total reaction force against the rotation force inside ballbearing includes sliding and rolling friction force at contact areas, the friction force between rolling elements and rolling paths, the friction force between rolling elements and the cage. Friction occurs because of lubricant movements and contact covers [2]. A ball bearing seal has 2 basic tasks; the lubricant in and keeping contaminates out of the bearing system. This separation must be accomplished between surfaces in relative motion, usually a shaft or bearing inner ring and a housing [3].
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Challenges Being Faced by Industries for Lubrication of Bearings in Wet Environments
Rama Kanth Yasaswi
Bearings operating in wet and contaminated environments can suffer from unreliability and very short service life, resulting in costly maintenance and downtime. This is particularly true for applications exposed to the elements and those that must undergo frequent washdowns. Attempts to extend service life in these conditions by frequent relubrication tend to be relatively unsuccessful and there is a risk of contamination of the product by the ejected used grease. CHALLENGES The presence of high moisture levels and water poses a unique set of challenges for bearings. There is no contaminant more complex, intense and confounding than water. The reasons are still being studied, but they include its various states of coexistence with the oil and its many chemical and physical transformations imparted during service. Individually and collectively, moisture-induced problems exact damage on both the oil and machine and can certainly lead, either slowly or abruptly, to operational failure of the bearing. When moisture or water enters the free space in a bearing, it decreases the effectiveness of the lubricant, which accelerates wear, increases frictional heat and corrodes the rolling elements and raceways. Water servicing effects on bearings in industries Water can damage machine surfaces directly, through a sequence of events and often with a variety of helpers. In many cases, the most severe damage is the cascading or chain reaction failure. For instance, water may lead first to premature oxidation of the base oil. When the oxides combine with more water, a corrosive acidic fluid environment exists. Applications in the food, beverage and pharmaceutical processing industries face additional challenges that result from frequent high pressure washdowns During washdown, integral bearing seals can deflect inward, allowing water to enter, and grease to be washed out of the bearing Grease washout risks contaminating the product and decreasing the effectiveness of any lubricant that remains in the bearing, leading to early failure.
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The Grooved Lip Effect on Reciprocating Hydraulic Rod Seal Performances in Transient Condition: Elastohydrodynamic Lubrication
Miloud Rahmoune
International Journal of Applied Mechanics and Engineering, 2020
It is commonly known that the sealing performance of dynamic seals is significantly influenced by the surface finish. To reduce friction effect and leakage ratio, new generations of grooved lip or shaft have emerged, but only two computational models were performed up to now with a textured elastomeric lip: spiral groove in the axial direction or micro-cavities according to the circumferential direction. However, if the numerical results have confirmed the slight effect of the grooved lip on the rotary lip seal performances, it seems relevant to investigate the influence of such grooves on the reciprocating hydraulic rod seal behavior. Thus, the scope of this work is to perform a parametric study of the grooved lip throughout a one-dimensional elastohydrodynamic model by taking into account the elasticity of the lip and the shaft roughness. After confirming the validity of the current model, numerical simulations have been performed and compared with experiments. The effect of lip g...
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Study the Possibility of Lubrication for Rolling Bearings
Gabriel Praporgescu
2013
In this paper are presented some methods of lubrication and calculating the volume of lubricant required by joints of friction, supply methods and filtering it. Key-words: lubrication, rolling bearings, joints of friction
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PROPER LUBRICANT SELECTION FOR BEARING APPLICATIONS Proper Lubricant Selection for Rolling Bearing Applications
Puchit Dumrongsupakitkul
Proper selection of lubricant is a decisive task in achieving the maximum possible bearing life for a certain application. In this paper a theoretical part concerning bearing lubrication and the RKB software dedicated to the proper lubricant selection are presented.
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An Investigation of the Fundamental Properties of Grease-Lubricated Bearings
Richard Buckholz
1982
: Grease is used as a lubricant for large numbers of bearings in everyday use; but the non-Newtonian rheological properties of these thixotropic gels, and their effect upon journal-bearing performance, are not well understood. To initiate a program in grease lubrication, we reactivated a concentric-cylinder journal-bearing test apparatus used by Smith and Fuller. This particular configuration has been treated extensively by theoreticians for constant viscosity lubricants, and to a considerably lesser extent for non-Newtonian lubricants. Smaller amounts of experimental data exist for both types of lubricants. The journal-bearing test apparatus was operated first as a concentric-cylinder viscometer, and the shear viscosity of SAE 10 oil measured. Subsequently, the apparent shear viscosity of a lithium-based grease (Sears and Roebuck) was measured as a function of rate of strain and of temperature. Performance of the grease-lubricated journal bearing was characterized by experimental d...
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Lubrication And Seal Oil Systems
ricardo stack
1984
with a B.S. degree in Mechanical Engineering/ Aerospace Option. Mr. Salisbury's product line respon sibilities include Elliott single and multi stage centrifugal compressors, axial compressors, process packaging, and lube/seal oil systems. The group he supervises is responsible fo r field support during installation, startup, operation, and trou bleshooting fo r each of the above product lines. His group is also responsible fo r technical training of our fa ctory and fi eld service engineers and service representatives. In addition, they are responsible fo r customer training on new and existing equipment. He has traveled extensively worldwide, developing tech niques to reduce troubleshooting time which directly affects plant down time. Approximately three years ago, his group opened their internal training course to customers and began teaching a fo ur-day seminar on lube and seal oil systems to end user rotating equipment engineers and instrument personnel. To date, over 15 individual companies have been represented at these seminars which are held biannually .
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Properties and Performance of Gas-Expanded Lubricants in Tilting Pad Journal Bearings
Paul Allaire
Tribology Transactions, 2013
Lubricants enable proper function and reduce friction in rotating machinery, but they can also contribute to power loss and heat buildup. Gas-expanded lubricants (GELs) have been proposed as tunable mixtures of lubricant and CO 2 under pressure with properties such as viscosity that can be controlled directly in response to changing environmental or rotordynamic conditions. In this work, experimental results of GEL viscosity, gas diffusivity, and thermal conductivity were combined with high-pressure phase equilibrium data to understand how these mixtures will behave in tilting pad journal bearings under a range of industry-relevant high-speed conditions. Simulations were carried out using the experimental data as inputs to a thermoelastohydrodynamic model of tilting pad journal bearing performance. Viscosity could be easily tuned by controlling the composition of the GEL and the effect on bearing efficiency was appreciable, with 14-46% improvements in power loss. This trend held for a range of lubricant chemistries with polyalkylene glycols, polyalpha olefins, and a polyol ester tested in this work. Diffusivity, which drives how readily CO 2 and lubricants form homogenous mixtures, was found to be a function of the viscosity of the synthetic lubricant, with more viscous lubricants having a lower diffusivity than less viscous formulations. Model results for a bearing in a pressurized housing suggested that cavitation would be minimal for a range of speed conditions. Other bearing parameters, such as eccentricity, temperature, and minimum film thickness were relatively unchanged between conventionally lubricated and GEL-lubricated bearings, suggesting that the efficiency improvements could be achieved with few performance tradeoffs.
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