The Axial Load-Carrying Capacity of Radial Cylindrical Roller Bearings

1970 ◽  
Vol 92 (1) ◽  
pp. 129-134 ◽  
Author(s):  
H. Korrenn
Keyword(s):  
Carrying Capacity ◽  
Hydrodynamic Lubrication ◽  
Experimental Investigations ◽  
Load Carrying Capacity ◽  
Oil Viscosity ◽  
Application Range ◽  
Roller Bearings ◽  
Load Carrying ◽  
Thrust Load ◽  
Cylindrical Roller

Thrust load transmission at the contact areas of roller ends and flanges occurs under conditions of pure sliding. Recent theoretical and experimental investigations showed that with adequately designed roller ends and flanges and with a satisfactory lubricant high thrust loads can be accommodated over a wide speed range with fully hydrodynamic lubrication. The conventional methods used for the determination of the safe thrust load should be revised and supplemented. Oil viscosity should be introduced as an important parameter. Contrary to present opinion the hydrodynamic load-carrying capacity at the flange increases with increasing speed. This new knowledge broadens the application range of radial cylindrical roller bearings.

scholarly journals Geometrical Optimization of the EHL Roller Face/Rib Contact for Energy Efficiency in Tapered Roller Bearings

Lubricants ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 67
Author(s):  
Sven Wirsching ◽  
Max Marian ◽  
Marcel Bartz ◽  
Thomas Stahl ◽  
Sandro Wartzack
Keyword(s):  
Energy Efficiency ◽  
Carrying Capacity ◽  
Tribological Behavior ◽  
Large Radius ◽  
Load Carrying Capacity ◽  
Statistical Design Of Experiments ◽  
Roller Bearings ◽  
Load Carrying ◽  
Tapered Roller ◽  
Tapered Roller Bearings

In the context of targeted improvements in energy efficiency, secondary rolling bearing contacts are gaining relevance. As such, the elastohydrodynamically lubricated (EHL) roller face/rib contact of tapered roller bearings significantly affects power losses. Consequently, this contribution aimed at numerical optimization of the pairing’s macro-geometric parameters. The latter were sampled by a statistical design of experiments (DoE) and the tribological behavior was predicted by means of EHL contact simulations. For each of the geometric pairings considered, a database was generated. Key target variables such as pressure, lubricant gap and friction were approximated by a meta-model of optimal prognosis (MOP) and optimization was carried out using an evolutionary algorithm (EA). It was shown that the tribological behavior was mainly determined by the basic geometric pairing and the radii while eccentricity was of subordinate role. Furthermore, there was a trade-off between high load carrying capacity and low frictional losses. Thereby, spherical or toroidal geometries on the roller end face featuring a large radius paired with a tapered rib geometry were found to be advantageous in terms of low friction. For larger lubricant film heights and load carrying capacity, spherical or toroidal roller on toroidal rib geometries with medium radii were favorable.

scholarly journals Two-scale homogenization of hydrodynamic lubrication in a mechanical seal with isotropic roughness based on the Elrod cavitation algorithm

2021 ◽  
pp. 135065012110176
Author(s):  
Yanxiang Han ◽  
Qingen Meng ◽  
Gregory de Boer
Keyword(s):  
Surface Topography ◽  
Carrying Capacity ◽  
Hydrodynamic Lubrication ◽  
Tribological Performance ◽  
Stribeck Curve ◽  
Polar Coordinate System ◽  
Load Carrying Capacity ◽  
Mechanical Seal ◽  
Macro Scale ◽  
Load Carrying

A two-scale homogenization method for modelling the hydrodynamic lubrication of mechanical seals with isotropic roughness was developed and presented the influence of surface topography coupled into the lubricating domain. A linearization approach was derived to link the effects of surface topography across disparate scales. Solutions were calculated in a polar coordinate system derived based on the Elrod cavitation algorithm and were determined using homogenization of periodic simulations describing the lubrication of a series of surface topographical features. Solutions obtained for the hydrodynamic lubrication regime showed that the two-scale homogenization approach agreed well with lubrication theory in the case without topography. Varying topography amplitude demonstrated that the presence of surface topography improved tribological performance for a mechanical seal in terms of increasing load-carrying capacity and reducing friction coefficient in the radial direction. A Stribeck curve analysis was conducted, which indicated that including surface topography led to an increase in load-carrying capacity and a reduction in friction. A study of macro-scale surface waviness showed that the micro-scale variations observed were smaller in magnitude but cannot be obtained without the two-scale method and cause significant changes in the tribological performance.

The Granular Lubricated Journal Bearing: Evidence of Lift Formation

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Venkata K. Jasti ◽  
Martin C. Marinack ◽  
Deepak Patil ◽  
C. Fred Higgs
Keyword(s):  
Carrying Capacity ◽  
Granular Flow ◽  
High Speed ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Flow Behavior ◽  
Extreme Environments ◽  
Granular Flows ◽  
Load Carrying Capacity ◽  
Load Carrying

This work demonstrates that granular flows (i.e., macroscale, noncohesive spheres) entrained into an eccentrically converging gap can indeed actually exhibit lubrication behavior as prior models postulated. The physics of hydrodynamic lubrication is quite well understood and liquid lubricants perform well for conventional applications. Unfortunately, in certain cases such as high-speed and high-temperature environments, liquid lubricants break down making it impossible to establish a stable liquid film. Therefore, it has been previously proposed that granular media in sliding convergent interfaces can generate load carrying capacity, and thus, granular flow lubrication. It is a possible alternative lubrication mechanism that researchers have been exploring for extreme environments, or wheel-regolith traction, or for elucidating the spreadability of additive manufacturing materials. While the load carrying capacity of granular flows has been previously demonstrated, this work attempts to more directly uncover the hydrodynamic-like granular flow behavior in an experimental journal bearing configuration. An enlarged granular lubricated journal bearing (GLJB) setup has been developed and demonstrated. The setup was made transparent in order to visualize and video capture the granular collision activity at high resolution. In addition, a computational image processing program has been developed to process the resulting images and to noninvasively track the “lift” generated by granular flow during the journal bearing operation. The results of the lift caused by granular flow as a function of journal rotation rate are presented as well.

Influence of tribofilms on failures and friction of gears with particular focus on running-in

2019 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Andreas Ziegltrum ◽  
Stefan Emrich ◽  
Thomas Lohner ◽  
Klaus Michaelis ◽  
Alexander Brodyanski ◽  
...  
Keyword(s):  
Surface Analysis ◽  
Carrying Capacity ◽  
Experimental Investigations ◽  
Spur Gears ◽  
Load Carrying Capacity ◽  
Friction Behavior ◽  
Content Type ◽  
Load Carrying ◽  
Gear Contact ◽  
Local Pressures

Purpose This paper aims to address the influence of tribofilms and running-in on failures and friction of gears. The operation regime of gears is increasingly shifted to mixed and boundary lubrication, where high local pressures and temperatures occur at solid interactions in the gear contact. This results in strong tribofilm formation due to interactions of lubricant and its additives with the gear flanks and is related to changes of surface topography especially pronounced during running-in. Design/methodology/approach Experiments at a twin-disk and gear test rig were combined with chemical, structural and mechanical tribofilm characterization by surface analysis. Pitting lifetime, scuffing load carrying capacity and friction of ground spur gears were investigated for a mineral oil with different additives. Findings Experimental investigations showed a superordinate influence of tribofilms over surface roughness changes on damage and friction behavior of gears. Surface analysis of tribofilms provides explanatory approaches for friction behavior and load carrying capacity. A recommendation for the running-in of spur gears was derived. Originality/value Experimental methods and modern surface analysis were combined to study the influence of running-in and tribofilms on different failures and friction of spur gears.

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