Application of a Mixed Lubrication Model for Hydrostatic Thrust Bearings of Hydraulic Equipment

1993 ◽  
Vol 115 (4) ◽  
pp. 686-691 ◽  
Author(s):  
Toshiharu Kazama ◽  
Atsushi Yamaguchi
Keyword(s):  
Surface Roughness ◽  
Power Loss ◽  
Mixed Lubrication ◽  
Power Losses ◽  
Thrust Bearings ◽  
Supply Pressure ◽  
Hydraulic Equipment ◽  
Hydrostatic Balance ◽  
Film Lubrication ◽  
Fluid Film Lubrication

On mixed and fluid film lubrication the characteristics of hydrostatic bearings for hydraulic equipment are studied numerically. By applying a mixed lubrication model derived in a previous paper to the bearings, we clarify the effects of the surface roughness, eccentric or moment loads, supply pressure and speed of rotation on the friction, flow rate, and power losses. Introducing the concept of a ratio of hydrostatic balance, we show that the minimum power loss is given as the ratio becomes close to unity.

Experiment on Mixed Lubrication of Hydrostatic Thrust Bearings for Hydraulic Equipment

1995 ◽  
Vol 117 (3) ◽  
pp. 399-402 ◽  
Author(s):  
Toshiharu Kazama ◽  
Atsushi Yamaguchi
Keyword(s):  
Flow Rate ◽  
Mixed Lubrication ◽  
Leakage Flow ◽  
Thrust Bearings ◽  
Leakage Flow Rate ◽  
Hydraulic Equipment ◽  
Load Carrying ◽  
Mean Pressure ◽  
Lubrication Characteristics ◽  
Hydrostatic Balance

Mixed lubrication characteristics of hydrostatic thrust bearings are examined experimentally. The effects of the surface roughness, supply pressure, loads, speed of rotation and size of restrictors on the frictional force, leakage-flow rate and power losses are clarified. Introducing the concept of mean pressure based on load-carrying capacity due to asperities, and the ratios of hydrostatic balance and leakage-flow rate, the experimental data can be normalized. Also good agreement is found between theoretical results based on a mixed lubrication model presented in a previous paper and the experiment.

scholarly journals Mixed and Fluid Film Lubrication Characteristics of Worn Journal Bearings

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Toshiharu Kazama ◽  
Yukihito Narita
Keyword(s):  
Frictional Coefficient ◽  
Journal Bearings ◽  
Mixed Lubrication ◽  
Operating Conditions ◽  
Fluid Film ◽  
Asperity Contact ◽  
Lubrication Regimes ◽  
Lubrication Characteristics ◽  
Film Lubrication ◽  
Fluid Film Lubrication

The mixed and fluid film lubrication characteristics of plain journal bearings with shape changed by wear are numerically examined. A mixed lubrication model that employs both of the asperity-contact mechanism proposed by Greenwood and Williamson and the average flow model proposed by Patir and Cheng includes the effects of adsorbed film and elastic deformation is applied. Considering roughness interaction, the effects of the dent depth and operating conditions on the loci of the journal center, the asperity-contact and hydrodynamic fluid pressures, friction, and leakage are discussed. The following conclusions are drawn. In the mixed lubrication regime, the dent of the bearing noticeably influences the contact and fluid pressures. For smaller dents, the contact pressure and frictional coefficient reduce. In mixed and fluid film lubrication regimes, the pressure and coefficient increase for larger dents. Furthermore, as the dent increases and the Sommerfeld number decreases, the flow rate continuously increases.

Optimum Design of Hydrostatic Spherical Bearings in Fluid Film Lubrication

2000 ◽  
Vol 122 (4) ◽  
pp. 866-869 ◽  
Author(s):  
Toshiharu Kazama
Keyword(s):  
Optimum Design ◽  
Analytical Solutions ◽  
Power Loss ◽  
Fluid Film ◽  
Optimal Size ◽  
Minimum Power ◽  
Maximum Stiffness ◽  
The Difference ◽  
Film Lubrication ◽  
Fluid Film Lubrication

The optimum design of hydrostatic spherical bearings in fluid film lubrication is examined theoretically. The analytical solutions are derived for both fitted and clearance types of bearings with capillary and orifice restrictors. The optimal size based on the minimum power loss and the maximum stiffness is presented, and the difference between two types of bearings is discussed. [S0742-4787(00)02204-9]

Mixed Lubrication of “Parallel” Plane Sliders

1972 ◽  
Vol 39 (1) ◽  
pp. 36-40
Author(s):  
D. S. Bedi ◽  
M. J. Hillier
Keyword(s):  
Theoretical Model ◽  
Friction Coefficient ◽  
Critical Speed ◽  
Mixed Lubrication ◽  
Parallel Plane ◽  
Stick Slip ◽  
Lubrication Conditions ◽  
Film Lubrication ◽  
Slip Phenomenon ◽  
Fluid Film Lubrication

A theoretical model for the friction coefficient indicates two critical speeds of sliding. The lower critical speed corresponds to a change-over from boundary to mixed lubrication conditions, the higher critical speed a transition to full fluid-film lubrication at angles of inclination less than 0.01 deg. The first critical speed appears to be associated with the “stick-slip” phenomenon.

scholarly journals A comparison of porous structures on the performance of slider bearing with surface roughness in micropolar fluid film lubrication

2019 ◽  
Vol 23 (3 Part B) ◽  
pp. 1813-1824 ◽  
Author(s):  
Pentyala Rao ◽  
Birendra Murmu ◽  
Santosh Agarwal
Keyword(s):  
Surface Roughness ◽  
Micropolar Fluid ◽  
Fluid Film ◽  
Porous Structures ◽  
Slider Bearing ◽  
Sphere Model ◽  
Load Carrying ◽  
Improved Performance ◽  
Film Lubrication ◽  
Fluid Film Lubrication

This paper presents the theoretical analysis of comparison of porous structures on the performance of a slider bearing with surface roughness in micropolar fluid film lubrication. The globular sphere model and Irmay?s capillary fissures model have been subject to investigations. The general Reynolds equation which incorporates randomized roughness structure with Stokes micropolar fluid is solved with suitable boundary conditions to get the pressure distribution, which is then used to obtain the load carrying capacity. The graphical representations suggest that the globular sphere model scores over the Irmay?s capillary fissures model for an overall improved performance. The numerical computations of the results show that, the act of the porous structures on the performance of a slider bearing is improved for the micropolar lubricants as compared to the corresponding Newtonian lubricants.

Factors Influencing Power Loss of Tilting-Pad Thrust Bearings

1979 ◽  
Vol 101 (2) ◽  
pp. 154-160 ◽  
Author(s):  
R. S. Gregory
Keyword(s):  
Power Loss ◽  
External Factors ◽  
Great Care ◽  
Power Losses ◽  
Thrust Bearings ◽  
Factors Influencing ◽  
Tilting Pad ◽  
Actual Size ◽  
Measured Power

Several recent technical papers have discussed the advantages of various designs of thrust bearings by comparing the power losses of the different type bearings. However, great care must be exercised to ensure that the comparisons are fair. There are many external factors that influence loss, such as oil flowrate, clearance, supply temperature and so on. Unless compensation for these external factors is included in the analysis, the power loss comparisons may be misleading. This paper attempts to show both qualitatively and quantitatively the influence that various external factors have on bearing power loss. It has been determined experimentally that oil flowrate adjustment can vary power loss by as much as 150 percent. The choice of radial or tangential discharge can reduce power loss by 60 percent, while the actual size of the discharge can influence power loss by 50 percent. Varying the bearing end play has little effect on measured power loss.

Analysis of mechanical power loss of a helical gear pair based on the starved thermal-elastohydrodynamic lubrication model

2019 ◽  
Vol 72 (3) ◽  
pp. 333-340
Author(s):  
Mingyong Liu ◽  
Peidong Xu ◽  
Jinxi Zhang ◽  
Huafeng Ding
Keyword(s):  
Surface Roughness ◽  
Tribological Properties ◽  
Power Loss ◽  
Elastohydrodynamic Lubrication ◽  
Helical Gear ◽  
Mechanical Power ◽  
Gear Pair ◽  
Content Type ◽  
Helical Gear Pair ◽  
Film Lubrication

Purpose Power loss is an important index to evaluate the transmission performance of a gear pair. In some cases, the starved lubrication exists on the gear contact interface. The purpose of this paper is to reveal the mechanical power loss of a helical gear pair under starved lubrication. Design/methodology/approach A starved thermal-elastohydrodynamic lubrication (EHL) model is proposed to evaluate the tribological properties of a helical gear pair. The numerical result has been validated against the published simulation data. Based on the proposed model, the influence of thermal effect, working conditions, inlet oil-supply layer and surface roughness on the mechanical power loss and lubrication performance has been discussed. Findings Results show that the thermal effect has a significant effect on the tribological properties of helical gear pair, especially on mechanical power loss. For a specified working condition, there is an optimal oil supply for gear lubrication to obtain the state of full film lubrication. Meanwhile, it reveals that the mechanical power loss increases with the increase of the surface roughness amplitude. Originality/value In this paper, a starved thermal-EHL model has been developed for the helical gear pair based on the finite line contact theory. This model can be used to analyze the tribological properties of gear pair from full film lubrication to mixed lubrication. The results can provide the tribological guidance for design of a helical gear pair.

A Study of the Role of Synovial Fluid and its Constituents in the Friction and Lubrication of Human Hip Joints

1978 ◽  
Vol 7 (2) ◽  
pp. 73-83 ◽  
Author(s):  
J. O'Kelly ◽  
A. Unsworth ◽  
D. Dowson ◽  
D. A. Hall ◽  
V. Wright
Keyword(s):  
Synovial Fluid ◽  
Mixed Lubrication ◽  
Fluid Film ◽  
Hip Joints ◽  
A Value ◽  
Continuous Dynamic ◽  
Film Lubrication ◽  
Fluid Film Lubrication ◽  
Lubrication Mechanisms

Human hip joints have been studied in a pendulum apparatus and a joint simulator to determine the lubrication mechanisms active in normal physiological activities. Various lubricants have been used to lubricate the hip joints including bovine and human synovial fluid, synovial fluid which has been digested with hyaluronidase or trypsin, silicone fluids of different viscosities, as well as synovial fluid and Ringer's solution which have had their viscosities increased by the addition of hyaluronic acid. The results indicate that under continuous dynamic loading, fluid film lubrication seems to prevail while under static loading, mixed lubrication exists. Increasing the viscosity of the lubricant from very low values (i.e. from 10-3 Pa.s) leads to a reduction in friction, indicating mixed lubrication, until a value of about 0.050 Pa.s was achieved. Further increases seemed to indicate that fluid film lubrication was then present.

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