Showing papers in "Tribology Transactions in 1987"
TL;DR: In this article, the friction coefficient of Si3N4 and SiC sliding against themselves and against each other in water at room temperature is described, with an estimated water film thickness of 70 nm.
Abstract: This report describes experiments on friction of Si3N4 and SiC sliding against themselves and against each other in water at room temperature. The friction coefficient of Si3N4 against itself is f = 0.7 at low speeds (0.2 cm/s). At speeds above 6.5 cm/s and 4.91-N load, hydrodynamic lubrication sets in, with f = <0.002 and an estimated water film thickness of 70 nm. Between 0.2 and 5 cm/s, mixed lubrication occurs. This remarkably thin hydrodynamic film is made possible by the tribochemical wear of Si3N4 which occurs by dissolution in water and an absence of wear particles. The friction coefficient of SiC, against SiC or Si3N4 in water at low speeds is f = 0.26. Wear occurs by dissolution and fracture pitting. Small wear particles are observed. The friction coefficient of SiC against SiC is independent of sliding velocity between 0.2 and 20 cm/s. Hydrodynamic lubrication is obtained with a Si3N4 pin on SiC plate near 10 cm/s, mixed lubrication is obtained with a SiC in on Si3N4 plate at v < 20 cm/s. Prese...
365 citations
TL;DR: A survey of important papers pertaining to thermal effects in journal bearings is presented in this article, which includes theoretical, computation, and experimental works pertaining to heat effects of journal bearings published in various technical journals.
Abstract: This Paper presents a survey of important papers pertaining to thermal effects in journal bearings. It includes discussions on theoretical, computation, and experimental works pertaining to heat effects in journal bearings published in various technical journals. Presented at the 4191 Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986
101 citations
TL;DR: In this article, the authors describe new compositions of self-lubricating coatings that contain chromium carbide, which are then plasma sprayed onto superalloy substrates and diamond ground to the desired coating thickness.
Abstract: This paper describes new compositions of self-lubricating coatings that contain chromium carbide. A bonded chromium carbide was used as the base stock because of the known excellent wear resistance and the chemical stability of chromium carbide. Additives were silver and barium fluoride/calcium fluoride eutectic. The coating constituents were treated as a ternary system consisting of: (1) the bonded carbide base material, (2) silver, and (3) the eutectic. A study to determine the optimum amounts of each constituent was performed. The various compositions were prepared by powder blending. The blended powders were then plasma sprayed onto superalloy substrates and diamond ground to the desired coating thickness. Friction and wear studies were performed at temperatures from 25 to 760 C in helium and hydrogen. A variety of counterface materials were evaluated with the objective of discovering a satisfactory metal/coating sliding combination for potential applications such as piston ring/cylinder liner couples for Stirling engines.
88 citations
TL;DR: An extensive survey of the papers pertaining to thermal effects in hydrodynamic bearings, particularly the slider/thrust bearings, is presented with a summary of the important contributions of leading researchers and designers as mentioned in this paper.
Abstract: An extensive survey of the papers pertaining to thermal effects in hydrodynamic bearings, particularly the slider/thrust bearings, is presented with a summary of the important contributions of leading researchers and designers Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986
82 citations
TL;DR: In this paper, the friction and wear properties of hard carbon amorphous films with a hot cathode glow discharge in ethylene or methane were examined using a reciprocating tribometer in vacuum and in air.
Abstract: The friction and wear properties of hard carbon films deposited by a hot cathode glow discharge in ethylene or methane were examined by using a reciprocating tribometer in vacuum and in air. A hard carbon film composed of mixed diamond and graphite crystal shows high friction in vacuum. On the other hand, hard carbon amorphous film containing hydrogen shows an extremely low friction coefficient on the order of 0.01 in vacuum.
76 citations
TL;DR: In this paper, a model utilizing simple structural defect theory in molecular monolayers quantitatively accounts for the relationship between measured friction coefficients at monolayer coverage and additive properties such as enthalpy of fusion, chain length, chain symmetry, and solubility in hydrocarbon media.
Abstract: A model utilizing simple structural defect theory in molecular monolayers quantitatively accounts for the relationship between measured friction coefficients at monolayer coverage and additive properties such as enthalpy of fusion, chain length, chain symmetry, and solubility in hydrocarbon media. This model is an extension of a recent model of boundary lubrication for a simple two-component lubricant (i.e., base lubricant and one additive) relating friction coefficient to surface coverage. For a given polar end group, it is shown that the lateral cohesive interactions between the hydrocarbon chains in the monolayer play the major role in reducing friction and that the sum total of these interactions approximates the enthalpy of fusion. The coupling between friction coefficient at monolayer coverage and solubility directly follows from thermodynamics. Presented at the 41st Annual Meeting, in Toronto, Ontarlo, Canada, May 12–15, 1986
54 citations
TL;DR: In this article, the fluid flow in an open-ends squeeze-film dampers due to small-amplitude circular-centered motions is considered and the linear flow equations are solved exactly for arbitrary values of the Reynolds number, and exact damping and inertia force coefficient are then derived for open ends SFDs with arbitrary L/D ratios.
Abstract: Fluid-film forces generated by squeeze-film dampers (SFD) in response to small-amplitude centered motions are of special interest for stability analyses of rotating machinery employing SFDs with strong centering springs. They form the basis for calculation of linearized damping and inertia force coefficients obtained by subjecting the journal center to very small perturbations in velocity and acceleration. The analysis considers the fluid flow in an open-ends SFD due to small-amplitude circular-centered motions. Simplified governing equations are derived; and regarding the flow to be stable and laminar, the linear flow equations are solved exactly for arbitrary values of the Reynolds number. Exact damping and inertia force coefficient are then derived for open ends SFDs with arbitrary L/D ratios. Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986
52 citations
TL;DR: In this paper, the adsorption of zinc n-, iso-, and s-dibutyldithiophosphates from n-hexadecane on iron and iron oxide powders was investigated in static conditions.
Abstract: The adsorption of zinc n-, iso-, and s-dibutyldithiophosphates from n-hexadecane on iron and iron oxide powders was investigated in static conditions. The effects of ZDTP concentration, time, and temperature were examined. ZDTP adsorption isotherms on both powders are very similar and are S-type. The adsorption kinetics cannot be represented by a Langmuir model. At higher temperatures, oxidation of ZDTP occurs on iron oxide surface; chemisorption sulfur products which are formed on iron surface were determined.
51 citations
TL;DR: A variety of MoS2 films having different initial surface compositions and different degrees of reaction in oxidizing atmospheres have been prepared by sputter deposition onto 440C steel substrates and the compositions of these films including their degree of oxidation and their molybdenum-sulfur stoichiometry have been determined by x-ray photoelectron and Auger electron spectroscopy immediately before the films were subjected to sliding wear tests.
Abstract: A variety of MoS2 films having different initial surface compositions and different degrees of reaction in oxidizing atmospheres have been prepared by sputter deposition onto 440C steel substrates. The compositions of these films, including their degree of oxidation and their molybdenum-sulfur stoichiometry, have been determined by x-ray photoelectron and Auger electron spectroscopy immediately before the films were subjected to sliding wear tests. These tests, which used, an inhouse, “ring-on-disk” apparatus operating in an inert atmosphere, involved rubbing coated specimens against initially uncoated, polished 440C steel coutersurfaces. Films that had approximately 30 to 40 percent of their surface layers oxidized to MoO3 gave the best wear results. In addition, the presence of elemental sulfur in the film surface layers appears to enhance wear life. These data are interpreted to mean that much better adhesion between the transfer film and he initially bare steel surface is obtained through chemical bon...
48 citations
TL;DR: A review of previous experimental measurements of squeeze film damper (SFD) forces is given in this paper, where the effect of fluid inertia on the pressure fields and forces is found to be significant.
Abstract: A review of previous experimental measurements of squeeze film damper (SFD) forces is given. Measurements by the authors of SFD pressure fields and force coefficients, for circular centered orbits with epsilon = 0.5, are described and compared with computer predictions. For Reynolds numbers over the range 2-6, the effect of fluid inertia on the pressure fields and forces is found to be significant.
47 citations
TL;DR: In this paper, it is suggested that as conditions are made more severe in a dry, sliding contact, a regime is eventually initiated in which friction is governed by heat flow, and two alternate closed-form results for friction can be derived.
Abstract: It is proposed that as conditions are made more severe in a dry, sliding contact, a regime is eventually initiated in which friction is governed by heat flow. If is suggested that in any given configuration a maximum allowable sulfate temperature can be defined, two alternate closed-form results for friction can be derived. It is suggested that this regime of friction could be relevant to polymers and elastomers due to their low thermal conductivity. The models are compared quantitatively and quantitatively with results in the literature. Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986
TL;DR: In this article, the influence of fluid inertia on the SFD force response to circular-centered motions of arbitrary amplitude is analyzed in detail, for finite length, locally sealed SFDs, integro-differential equations are derived in terms of the mean flow components.
Abstract: The influence of fluid inertia on the SFD force response to circular-centered motions of arbitrary amplitude is analyzed in detail, For finite length, locally sealed SFDs, integro-differential equations are derived in terms of the mean flow components. Numerical predictions, using the finite-element method, show that the damping and added mass coefficients remain invariant as the Reynolds number increases from small values to a moderate Reynolds number equal to 10. An approximate, finite-length, solution for the fluid-film forces has been analytically obtained which accounts for the fluid-inertia effect as well as local end seal effects in symmetric SFD configurations. The approximate solution, strictly valid for small Reynold numbers (Re < 1), agrees well with the results from the numerical solution for most SFD configurations and orbit radii considered. Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE Tribology Conference in Pittsburgh, Pennsylvania, October 20–22, 1986
TL;DR: In this paper, a test rig has been designed and developed to study the effects of lubricant reduction on the threshold of cage gross skidding in a 35mm-bore, angular contact ball bearing.
Abstract: Ball bearings operating below the minimum load limits experience large-scale sliding and, consequently, premature fatigue failure. A test rig has been designed and developed to study the effects of lubricant reduction on the threshold of cage gross skidding in a 35-mm-bore, angular-contact ball bearing. The experimental results were also correlated with the data from a computer model. The minimum load limit is decreased when the oil supply is reduced. This reduction of the minimum safe load is more pronounced at higher shaft speeds. Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE Tribology Conference in Pittsburgh, Pennsylvania, October 20–22, 1986
TL;DR: In this article, the authors derived damping and inertia force coefficients for finite-length squeeze-film dampers by implementing a correction factor to the long SFD model solution, which is of extreme simplicity and shows excellent agreement with a numerical solution to the differential equations for the pressure.
Abstract: Fluid-film forces generated by squeeze-film dampers (SFD) in response to small-amplitude motions about an off-center equilibrium configuration are of considerable importance for stability analyses of rotating machinery employing SFDs with weak or no centering springs. This approach is the basis for calculation of linearized force coefficients obtained by subjecting the journal to small perturbations in velocity and acceleration. The analysis considers the fluid flow in an open-ended SFD due to small-amplitude motions of the journal center about the static equilibrium configuration. Simplified governing equations are derived from the full Navier-Stokes equations by order of magnitude tests. Approximate damping and inertia force coefficients for finite-length SFDs are derived by implementing a correction factor to the long SFD model solution. This finite-length correction is of extreme simplicity and shows excellent agreement with a numerical solution to the differential equations for the pressure including...
TL;DR: In this paper, the effect of cage and roller slip on the measured defect frequency response of rolling-element bearings using high-frequency resonance technique (HFRT) as a survelliance module was reported.
Abstract: The paper reports the effect of cage and roller slip on the measured defect frequency response of rolling-element bearings using high-frequency resonance technique (HFRT) as a survelliance module. The differences in theoretically calculated and experimentally determined defect frequencies have been used to identify percentage cage slip and roller slip in various bearings under no-load and load conditions at different speeds of operation. Various defect frequencies and their energy levels are used to monitor the severity of defects and complex response interactions of rolling elements with inner and outer rings of the bearings. It is shown that negative cage and roller slip is predominant at moderate speed under no-load and load operation. Positive slip is significant at high speed under no-load operation. Negative cage and roller slip is indicated by the presence of outer-race linear defect frequency along with rolling-element defect frequency, whereas positive slip is shown by inner race accompanied with...
TL;DR: In this article, the wear of a solid-lubricated ball bearing for high-speed turbine applications is considered in terms of local interactions and the overall dynamics of the bearing elements.
Abstract: Computer modeling of wear in a solid-lubricated ball bearing for high-speed turbine applications is considered in terms of local interactions and the overall dynamics of the bearing elements. With prescribed coefficients of wear at the various interfaces between the interacting bearing elements, the computer model ADORE is used to obtain the time-averaged wear rates for the balls, races, and the cage as a function of the operating conditions typical of a gas turbine application. The model presents analytical estimates of wear in the ball pockets and at the guide lands of the cage, and it provides some guidance for optimizing cage design in solid-lubricated ball bearings. Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986
TL;DR: The Amontons-Coulomb law of sliding friction is used to analyze a line contact elasticity model in which the contact stresses and tangential displacement relevant to fretting fatigue are calculated as mentioned in this paper.
Abstract: The Amontons-Coulomb law of sliding friction is used to analyze a line contact elasticity model in which the contact stresses and tangential displacement relevant to fretting fatigue are calculated. Once the numerical analysis is verified, the effects of finite thickness and tangential loading are calculated and their influence on fretting fatigue is discussed. The results are shown to compare well with previous experimental observations on a qualitative basis and a refinement of the model that would lead to quantitative experimental comparisons is suggested. Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986
TL;DR: In this paper, a novel test apparatus was built to measure the interface friction between a single cam-lifter pair isolated from other frictional components in the value train, and detailed investigations were made, for both a conventional lifter and a roller lifter.
Abstract: A novel test apparatus was built to measure the interface friction between a single cam-lifter pair isolated from other frictional components in the value train. Detailed investigations were made, for both a conventional lifter and a roller lifter. Measured results showed an 80 percent reduction in friction with the use of the roller lifter and the trend of decreasing friction with engine speed for both types of lifters. The observed lack of friction reduction over any part of the contact cycle and the large coefficient of friction in the case of the conventional lifter ruled out the possibility of elastohydrodynamic lubrication at the contact. Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986
TL;DR: In this article, the influence of pressure on the density of six base fluids was experimentally studied for a range of pressures from 0.422 to 2.20 GPa, and a formula was developed that describes the effect of pressure in terms of four constants.
Abstract: The influence of pressure on the density of six base fluids was experimentally studied for a range of pressures from 0.422 to 2.20 GPa. An important parameter used to describe the results is the change in relative volume with change in pressure dvr/dp. For pressures less than the solidification pressure (p ps), there was no change in dr/dp with changing pressure. The solidification pressures of the base fluids varied considerably, as did the slopes that the experimental data assumed, for p < pv. A formula was developed that describes the effect of pressure on density in terms of four constants. These constants vary for the different base fluids tested. Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986
TL;DR: In this paper, an AC impedance technique, in combination with an electrical property cell, was employed to measure the electrical resistance and capacitance of lubricants, and a comparison of the combined surface coating plus bulk fluid resistance, measured for different additives blended in mineral oil, demonstrated that different metal-lubricant interaction mechanisms occur.
Abstract: An AC impedance technique, in combination with an electrical property cell, was employed to measure the electrical resistance and capacitance of lubricants. A comparison of the combined surface coating plus bulk fluid resistance and capacitance values measured for different additives blended in mineral oil, demonstrated that different metal-lubricant interaction mechanisms occur. The electrical measurements indicated that additives such as the mixed alkyl acid orthophosphate (acid phosphate) reacted with the cast iron electrodes to firm reaction films, whereas oleic acid was absorbed on the electrodes. Although the implied reactivity from electrical measurement for N-oleyl-1-1,3 diaminopropane (fatty amine) is comparable to that for acid phosphate, no reaction film for the former was detected by elemental analysis. Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986
TL;DR: In this paper, a stable, turbulent two-phase fluid flow in a rotating annular seal with no eccentricity is analyzed, where the fluid is assumed to be a homogeneous mixture of liquid and vapor in thermodynamic equilibrum.
Abstract: Steady, turbulent two-phase fluid flow in a rotating annular seal with no eccentricity is analyzed. The fluid is assumed to be a homogeneous mixture of liquid and vapor in thermodynamic equilibrum. Further, the flow is assumed to be adiabatic, but the effects due to heat generation by viscous dissipation are accounted for fully. Solution of the model governing differential equations is accomplished by use of a fourth-order Runge-Kutta numerical integration scheme. The calculation of mass leakage rates under choked and unchoked conditions are discussed and the phenomenon of all-liquid choked flow is explained. Several numerical examples are presented supposing cyrogenic oxygen as the sealed fluid.
TL;DR: In this article, an approximate solution technique for axially grooved fluid film journal bearings is presented, making use of earlier approximations for the axial pressure distribution and the circumferential temperature variation and extending the theory to include heat transfer between the film and the bearing and journal.
Abstract: An approximate solution technique for axially grooved fluid film journal bearings is presented. The method makes use of earlier approximations for the axial pressure distribution and the circumferential temperature variation and extends the theory to include heat transfer between the film and the bearing and journal. A second-order profile is assumed to represent the temperature distribution across the film. The classical Reynolds equation is applied, using the viscosity determined by the cross-film average of temperature. The conduction of heat through the bearing is modeled in two dimensions by using a series expansion for the temperature in the sleeve, and the journal surface temperature is given by a circumferential average of film temperatures. Results are compared with those of another theory by Lund and with experimental results. The predicted temperatures agree with experiment over the loaded part of a two-axial-groove bearing but not as well in the unloaded part. They agree closely with those giv...
TL;DR: In this paper, the effect of other lubricating oil additives on the zinc di-isobutyldithiophosphate adsorption from n-hexadecane onto iron and iron oxide surfaces has been measured under static conditions.
Abstract: The effect of the other lubricating oil additives on the zinc di-isobutyldithiophosphate adsorption from n-hexadecane onto iron and iron oxide surfaces has been measured under static conditions. For different ZDTP concentrations, temperatures and for both iron and iron oxide ZDTP, adsorption was reduced by the other additives. During adsorption at 80°C, the other additives reduced thiophosphate and sulfide formation on the iron oxide most of the other additives investigated increased the oxidation of ZDTP to bis /O,O-diisobutyldithiophosphoryl/disulfide.
TL;DR: In this paper, the influence of mutual overlap coefficient (MOC) on the wear of five plastics, both filled and unfilled, in an oscillating pin-on-disk geometry at two different contact temperatures was investigated.
Abstract: Dry sliding materials are frequently wed in mechanical components featuring oscillatory motion. The wear of those materials is influenced by many mechanical and geometric parameters, but one geometric parameter that has proven to be of particular importance in oscillating pin-on-disk contacts is the mutual overlap coefficient (MOC). The MOC is the ratio of the area of contact of the pin to the area of the wear track on the counterface. The goal of this study was to characterize the influence of the MOC on the wear of five plastics, both filled and unfilled, in an oscillating pin-on-disk geometry at two different contact temperatures. The results showed that two characteristic wear behaviors occurred at a given temperature as a function of the MOC. At a large MOC, a central zone appeared in the contact and the elimination of wear debris from that zone was determined by the ratio of the amplitude of motion to the length of the pin in the direction perpendicular to the motion. A systematic series of tests sh...
TL;DR: In this article, the friction properties of several solid-lubricant films were examined by using a reciprocating tribometer in a vacuum and in air and the damage profile of oscillatory bearings corresponds to the profile of the contact elliptic area.
Abstract: The purpose of this work is to clarify the oscillatory performances of ball bearing for vacuum application. The friction properties of several solid-lubricant films were examined by using a reciprocating tribometer in a vacuum and in air. Ball bearings lubricated with the same solid-lubricant films were then tested under small-angle oscillatory conditions. Bearing lubricated with Ag + MoS2 show the lowest starting torque and surface damage. This result corresponds to sliding tests results. The damage profile of oscillatory bearings corresponds to the profile of the contact elliptic area. The rolling scars are mainly caused by the differential slip between balls and races.
TL;DR: In this paper, the authors consider the use of active feedback control for axial pulsating forces in a machine to reduce the vibration or transmitted force of the main support of a main support.
Abstract: In certain applications, axial pulsating forces in a machine need to be isolated so as to reduce the vibration or transmitted force of the main support. This paper illustrates the trade-offs that must be considered for such vibration isolation. It considers tile use of active feedback control and duly notes the control algorithm difficulties that are anticipated in the use of a magnetic bearing as the means for implementing the isolation. Complete vibration isolation is theoretically possible in a machine over certain frequency ranges for a sinusoidally varying exciting force, but at the cost of large vibration amplitudes of the shaft or very large control forces at low frequencies. Conversely, optimum (reduced) transmitted forces may be determined on the basis of a maximum prescribed amplitude of vibration that is acceptable for a particular machine. Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986
TL;DR: In this article, an analysis was performed to determine the effects of inner-ring speed and press fits on roller bearing fatigue life, and the effect of the resultant hoop and radial stresses on the principal stresses were considered.
Abstract: An analysis was performed to determine the effects of inner-ring speed and press fits on roller bearing fatigue life. The effects of the resultant hoop and radial stresses on the principal stresses were considered. The maximum shear stresses below the Hertzian contact were determined for different conditions of inner-ring speed and load, and were applied to a conventional roller bearing life analysis. The effect of mean stress was determined using Goodman diagram approach. Hoop stresses caused by press fits and centrifugal force can reduce bearing life by as much as 90 percent. Use of a Goodman diagram predicts life reductions of 20 to 30 percent. The depth of the maximum shear stress remains virtually unchanged.
TL;DR: In this paper, the authors collected persuasive qualitative experimental support to this effect and proposed a quantitative treatment deriving the friction or wear coefficients as functions of the heats of adsorption of boundary lubricant molecules.
Abstract: Theories explaining the way in which liquid-surface interaction affect boundary lubrication are reviewed. In all views, adsorption is a critical step governing the end result—albeit through differing mechanism. This review collects persuasive qualitative experimental support to this effect. A quantitative treatment deriving the friction or wear coefficients as functions of the heats of adsorption of boundary lubricant molecules is discussed in more detail, and recommendations for testing existing models are made. Methods for measuring heats of adsorption are described and the interrelation between the different measurements is explained. Heat of adsorption values predicted from sliding friction and wear measurements are higher than the integral heats of adsorption measured for the lubricant. This discrepancy could mean that a differential heat (i.e., specific for a certain surface coverage) determines the friction and wear characteristics of the lubricant-surface combination or that the surface temperatur...
TL;DR: In this paper, a statistical approach was used to evaluate the oxidation stability of neutral base oil blends in terms of their chemical structure, and different oxidation bench methods were applied to follow deterioration of the oils through the initial, breakdown, and final oxidation stages.
Abstract: A statistical approach was used to evaluate the oxidation stability of neutral base oil blends in terms of their chemical structure. Different oxidation bench methods were, therefore, applied to follow deterioration of the oils through the initial, breakdown, and final oxidation stages. For the initial stage, a statistical blocking of data was used in terms of the absence or presence of diaromatics to improve the derived correlations. Mathematical equations were derived for zero diaromatic oils by simple linear curve fitting while the application of multiple linear regression gave meaningful models for the diaromatics-containing oils. In the breakdown and final oxidation stages, significant models were obtained by multiple linear regression using five different chemical structure independent variables. To check the statistical validity of the derived models, the “F” values and correlation coefficients “R2” were calculated where their values proved the validity with a minimum of 95 percent confidence. The ...
TL;DR: In this paper, an analytic investigation into the flow pattern in load-capacity optimized-profile-film thrust bearings is presented, showing that recirculatory flow can occur near to the inlet with some film shapes and becomes more extensive as bearing width increases.
Abstract: An analytic investigation into the flow pattern in load-capacity optimized-profile-film thrust bearings is presented. This work shows that recirculatory flow can occur near to the inlet with some film shapes and becomes more extensive as bearing width increases. Of the film profiles investigated, lubricant flow reversal was most, significant in the quadratic type. When compared with linear film, the profile geometries gave enhanced load-carrying ability, but this was accompanied by a decrease in lubricant flowrate and an increase in power consumption. Lubricant inertia effects were most significant for the linear film profile giving increase in load-carying capacity and a decrease in lubricant flow over that where lubricant acceleration was excluded, power losses were affected only marginally.