Showing papers in "Tribology Transactions in 1972"
TL;DR: The analysis of grease-lubricated rolling element bearings is presented in this article, where a theory for predicting roller film thickness based on the assumed flow model is derived, and the results show that grease will develop a larger film thickness than the base oil at first but the film thickness falls during rolling until it reaches a steady thickness usually lower than that of its base oil.
Abstract: The analysis of grease-lubricated rolling element bearings is presented. Experimentally determined flow curves for grease are found to be well correlated by the Herschel-Bulkley model flow equation. A theory for predicting roller film thickness based on the assumed flow model is derived. Experimental results show that grease will develop a larger film thickness than the grease base oil at first, but the film thickness falls during rolling until it reaches a steady thickness usually lower than that of its base oil. This effect is shown to depend on the degree of shear degradation of the grease, its resulting flow curve, and the temperature rise due to shear in the inlet. The grease yield stress is found to have a negligible effect on EHL performance. Presented at the 27th ASLE Annual Meeting in Houston, Texas, May 1–4, 1972
79 citations
TL;DR: In this paper, the effect of particle size on the lubricating effectiveness of molybdenum disulfide has been investigated, and it was found that using larger MoS2 particles at increasing loads, the wear rate also increased.
Abstract: In trying to clarify the effect of particle size on the lubricating effectiveness of molybdenum disulfide, extensive tests with different MoS2 powders and MoS2 suspensions have been run. Because many of the test results available were obtained with the four-ball tester, these tests were also accomplished mainly with this machine, in order to provide a comparison. As a result, it was found that using larger MoS2 particles at increasing loads, the wear rate also increased. With finer particles at aggravating sliding conditions, the lubricating effectiveness was improved. This result may be explained in that at a given concentration, finer particles more easily will form a complete and continuous film than coarser particles, because there are more particles available. But the temperature, the materials and, especially, the roughness of the surfaces of the sliding parts must be taken into account, in order to transfer these results to other conditions. Presented at ASLE International Conference on Solid Lubri...
44 citations
TL;DR: In this paper, a very wide range of lubricants have been tested by optical elastohydrodynamics and their pressure viscosity coefficients agree well with those determined in conventional high-pressure viscometers.
Abstract: A very-wide-ranging series of lubricants have been tested by optical elastohydrodynamics. The pressure viscosity coefficients so found agree well with those determined in conventional high-pressure viscometers. Deviations from Newtonian behavior show up clearly, and some oils containing viscosity index improvers have, at these high shear rates, an effective viscosity only a few percent higher than their base oils. The perfluorinated alkyd polymers all have the same pressure viscosity coefficient irrespective of their base viscosity. Oils with surfactants do not show any modified surface viscosities; the conflict of this result with other measurements is discussed; and a possible resolution of the difficulty suggested. The aging of oils can be detected from the test results. The change from boundary to full fluid lubrication can be studied by this method. Its use as a secondary viscometer, using an accurate equation derived experimentally, is discussed. Presented as an American Society of Lubrication Engin...
40 citations
TL;DR: Auger emission spectroscopy, low energy electron diffraction, sputtering studies, and adhesion and friction experiments on single crystals of Cu-Sn, Cu-Al, and Fe-Al alloys were performed as mentioned in this paper.
Abstract: Auger emission spectroscopy, low energy electron diffraction, sputtering studies, and adhesion and friction experiments on single crystals of Cu-Sn, Cu-Al, and Fe-Al alloys
33 citations
TL;DR: In this paper, the electron distribution is inferred from a simplified chemical bonding scheme which is based on interactions between atomic orbitals and on the structural parameters of the materials, and comparisons in structure and properties are made between graphite and boron nitride, and between the disulfides and diselenides of niobium, molybdenum, tantalum, tungsten and rhenium.
Abstract: The wide variations in lubricating properties among candidate solid lubricants with similar crystal structures are explained in terms of the distribution of valence electrons in the various materials. The electron distribution is inferred from a simplified chemical bonding scheme which is based on interactions between atomic orbitals and on the structural parameters of the materials. Comparisons in structure and properties are made between graphite and boron nitride, and between the disulfides and diselenides of niobium, molybdenum, tantalum, tungsten and rhenium. Presented at the 27th ASLE Annual Meeting in Houston, Texas, May 1–4, 1972
31 citations
TL;DR: In this paper, the influence of steel composition on the formation of surface coatings, friction, fatigue, and static immersion studies were conducted with two case-hardened steels (1018 and 4118) and five through-Hardened materials (51100, 52100, M-50, 440-C, and Stellite #3).
Abstract: Coatings formed by lubricants on rubbing surfaces are believed to control the friction, wear, and fatigue of rolling contact bearings, gears, cams and tappets, and other heavily loaded components. To investigate the influence of steel composition on the formation of these surface coatings, friction, fatigue, and static immersion studies were conducted with two case-hardened steels (1018 and 4118) and five through-hardened materials (51100, 52100, M-50, 440-C, and Stellite #3). More surface coating formed on the low alloy steels than on the high alloy steels, with the composition of the oxide layer apparently being the controlling factor. The magnitude of the steel effect depended on the additive and the oxygen available. Elemental analyses of the surface coatings obtained with representative additives indicated that all contained significant organic fractions. Decomposition of the additive in the bulk oil was a necessary prerequisite for surface coating formation. Additive decomposition was generally prom...
29 citations
TL;DR: In this article, a MoS2/graphite (90/10) bonded solid film lubricant was tested in controlled-humidity environments and the average steady-state coefficient of friction increased from 0.23 to 0.28 as relative humidity (RH) was raised from 10 percent to 50 percent.
Abstract: Low-load slow-speed sliding friction tests were conducted on a MoS2/graphite (90/10) bonded solid film lubricant in controlled-humidity environments. The average steady-state coefficient of friction increased from 0.23 to 0.28 as relative humidity (RH) was raised from 10 percent to 50 percent, and it increased to 0.6 when RH reached 90 percent. At RH ≥80 percent, friction response was strongly influenced by chemically reactive metals used for slider and lubricant substrate. Thus, friction with carbon steel sliders was significantly lower than with stainless steel sliders, although corrosion of the former caused rapid destruction of the lubricant film. Also, continued sliding by stainless steel on lubricant applied to phosphor-bronze eventually resulted in a significant friction decrease and simultaneous formation of a dark red-brown film in the wear track. The proposed explanation for these effects is based on oxidation of MoS2 at the sliding interface and reaction of the oxidation products with slider an...
28 citations
TL;DR: In this article, a reduction in rolling contact fatigue life as high as 80% were observed during flood-lubricated angular contact ball bearing studies when 1% by volume of seawater was added to various lubricants as a contaminant.
Abstract: Reductions in rolling contact fatigue life as high as 80% were observed during flood-lubricated angular-contact ball bearing studies when 1% by volume of seawater was added to various lubricants as a contaminant. The lubricants investigated were of different chemical and physical classes and included mineral oils, triaryl phosphate, and two recently developed mineral-oil-base seawater-emulsifying hydraulic fluids of different viscosities. A shift in failure distribution, from ball failures to inner and outer race failures, is observed when seawater is added.
22 citations
BP1
TL;DR: In this article, the integral heat of preferential adsorption of n-dotriacontane and n-butanol using flow calorimeter is calculated for graphite and MoS2 powders.
Abstract: Recent work on graphite and MoS2 powders revealed that the proportion of basal plane surface in the powder is an important factor in their anti wear properties and that the proportion of the polar “edge” surface may affect the abrasive properties of these solid lubricants. A method has been developed, therefore, for the independent measurements of the total basal plane and edge surfaces in the powders. The basal plane area is determined from the amount of adsorption of n-dotriacontane from solution in n-heptane. Similarly the edge area is determined from the adsorption of n-butanol. A convenient and rapid method of estimating the proportions of basal plane and edge areas in the solid lubricants is to determine the integral heat of preferential adsorption of n-dotriacontane and n-butanol using the flow calorimeter. The saturation of a sample of graphite or MoS2 powder can be carried out by percolation with a succession of dilute solutions in n-heptane, and the total heats evolved are obtained in the form o...
20 citations
TL;DR: An Auger cylindrical mirror spectrometer has been incorporated into a friction and wear apparatus as discussed by the authors, which can analyze for all elements heavier than helium present on a friction-and wear surface.
Abstract: An Auger cylindrical mirror spectrometer has been incorporated into a friction and wear apparatus. The spectrometer can analyze for all elements heavier than helium present on a friction and wear surface. The instrument response is sufficiently fast to allow a chemical analysis of the surface in 0.10 second. The surface can be continuously analyzed while the experiment is in progress, and better insight into those chemical factors influencing friction and wear can thereby be provided. In sliding friction experiments, transfer of silver, aluminum, and copper to a steel surface was observed. Transfer took place without any attempt to clean the steel surface. This occurred in the first pass of the rider across the steel. Variations in the mode of metal transfer could also be detected. Gases containing oxygen were adsorbed to a copper transfer film, and its subsequent friction-initiated desorption was monitored. Presented at the 27th ASLE Annual Meeting in Houston, Texas, May 1–4, 1972
19 citations
TL;DR: In this article, the axial movement of piston rings is assumed to be connected with the increase of a blow-by, engine noise, wear, ring breakage etc. The first and second ring movements in each groove, and the pressure changes in the combustion chamber and in the space between the top and second rings (p2) have been measured simultaneously in a high speed automobile engine, using the rectangular “floating” taper-face and L-type piston rings.
Abstract: The axial movement of piston rings is presumed to be connected with the increase of a blow-by, engine noise, wear, ring breakage etc. The first and second ring movements in each groove, and the pressure changes in the combustion chamber (p1) and in the space between the top and second ring (p2) have been measured simultaneously in a high speed automobile engine, using the rectangular “floating” taper-face and L-type piston rings. The results are as follows: 1. The top ring lifts up when pressure p1 becomes equal to p2. In this case, however, gas leakage does not increase. As long as the top ring's posture is normal, it never lifts. 2. The second ring lifts up before TDC at higher than any critical speed because p2 is very low and inertia force is large. In this case, gas leakage increases greatly. 3. In case of the taper face ring as a second one, the larger the taper angle, the lower the critical speed. 4. L-ring movement is complicated because it is laid in arch-shape on the lower surface of groove. Pre...
TL;DR: In this article, a model for the contact of lubricated machine components has been developed from which the asperity or metal-to-metal contact load can be derived, and it is demonstrated by applying it to both a journal and a rolling element bearing.
Abstract: A model for the contact of lubricated machine components has been developed from which the asperity or metal-to-metal contact load can be derived. The model is developed for the contact of two cylinders, and it is demonstrated by applying it to both a journal and a rolling element bearing. The solution gives the asperity load as a function of the load applied to the components, the properties of the lubricant, and the properties of the contacting surfaces. It is postulated that the asperity load thus derived can be used in the linear wear law, so that the wear of lubricated cylindrical contacts can be predicted. In order to develop the model, the surface theory of Greenwood and Williamson was combined with the hydrodynamic lubrication theory of Dowson and Higginson. Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE Lubrication Conference held in Pittsburgh, Pennsylvania, October 5–7, 1971
TL;DR: In this article, an experimental rig was developed to measure the variation of the preload and friction torque in a pair of angular contact ball bearings under operating conditions, and the results indicated that the frictional losses in mainspindle assemblies may occur if the speed range is simply extended.
Abstract: The continuing development of cutting tool materials allows further increases in the speed of machine tool spindles to be made. The majority of rolling bearings used in mainspindle assemblies are preloaded to maintain adequate stiffness and lack of play at low speeds. However, unacceptable thermal distortion of machine structures may occur if the speed range is simply extended. In the last decade research into the lubrication of high pressure sliding contacts has identified and quantitatively evaluated the parameters which govern the frictional losses in such situations, and the study of elastohydrodynamic lubrication has evolved. Practical applications of this work have been made, but little has been reported on the transient variation of the preload and accompanying frictional losses in mainspindle assemblies under operating conditions. This paper describes an experimental rig developed to measure the variation of the preload and friction torque in a pair of angular contact ball bearings. The results il...
TL;DR: In this article, a rolling fatigue tester of simple construction, well suited to multiple-rig data gathering but also possessing considerable versatility and ease of variable control, is described and its kinematic and elasto-hydrodynamic relationships for two commonly used test specimen configurations are also presented.
Abstract: A rolling fatigue tester of simple construction, well suited to multiple-rig data gathering but also possessing considerable versatility and ease of variable control, is described. Its kinematic and elasto-hydrodynamic relationships for two commonly used test specimen configurations are also presented. Ten such testers were employed to evaluate the rolling fatigue lives of two typical aviation gas turbine lubricants. A total of 100 tests were conducted with each lubricant, comprising 10 tests on each of the 10 testers. The test conditions were such that the operation was definitely in the boundary lubrication regime. The rolling fatigue lives of the two lubricants under these conditions were found to be nearly the same at 90 percent confidence level, despite their difference in viscosities. Using the results obtained, an analysis was made of the statistical implications and economic considerations involved in multiple-rig rolling fatigue testing. Results presented include the effects of tester-to-tester v...
TL;DR: In this paper, the authors present a literature review on chemical reactions between solids, in which the chemical activation energy is generated by mechanical forces, and a review on the reactions occurring between solid lubricants such as MoS2 and Zn2P2O7 and metal surfaces.
Abstract: A historical background on chemical reactions between solids, in which the chemical activation energy is generated by mechanical forces, is presented and a literature review on “mechano-chemical” or “tribo-chemical” reactions occurring between solid lubricants such as MoS2 and Zn2P2O7 and metal surfaces is given. According to the work reviewed, MoS2 reacts with steel surfaces under boundary friction conditions forming FeS on the surface, and Zn2P2O7 forms iron phosphides. Presented at the 27th ASLE Annual Meeting in Houston, Texas, May 1–4, 1972
TL;DR: In this paper, it was shown that pyrophosphates can explain the lubrication mechanism of graphite and molybdenum disulfide, as well as other solids such as inorganic phosphates, oxides, hydroxides and sulfides.
Abstract: It is shown that besides graphite and molybdenum disulfide, other solids such as certain inorganic phosphates, oxides, hydroxides, and sulfides can be used for the preparation of lubricating mineral oil suspensions and pastes. With these compounds the range of lubrication by solids can be extended to such applications in which, up to now, molybdenum disulfide and graphite could not be used due to their black color or some other physical properties. In the case of pyrophosphates it is found that chemical reactions can explain, in part, the lubrication mechanism. Presented at ASLE International Conference on Solid Lubrication, held in Denver, Colorado, August 24–27, 1971
TL;DR: In this paper, electron diffraction patterns and electron micrographs of molybdenum disulfide films sputtered on single NaCl-crystal and electropolished aluminum substrates are presented as evidence that crystalline MoS2 films can be sputtered onto various substrates in thicknesses up to 2 microns.
Abstract: Electron diffraction patterns and electron micrographs of molybdenum disulfide films sputtered on single-NaCl-crystal and electropolished-aluminum substrates are presented as evidence that crystalline MoS2 films can be sputtered onto various substrates in thicknesses up to 2 microns. Applied to Falex test pins and V-blocks, some of these films exhibited a wear life as long as 65 minutes at 1000 lb jaw load.
TL;DR: Wear tests of oxide and fluoride oxidation resistant solid lubricants for use in high temperature gaseous environments were conducted by as discussed by the authors, showing that they are suitable for high temperature environments.
Abstract: Wear tests of oxide and fluoride oxidation resistant solid lubricants for use in high temperature gaseous environments
TL;DR: In this paper, the influence of temperature-dependent physical properties on the total temperatures predicted in the high-speed sliding of unlubricated SAE 1113 steel surfaces was examined. But the authors focused on the case where the subsurface temperatures were assumed equal and the predicted total temperature was the maximum value attainable.
Abstract: The paper examines the influence of temperature-dependent physical properties on the total temperatures predicted in the high-speed sliding of unlubricated SAE 1113 steel surfaces. The calculations are based on experimentally determined subsurface temperatures, friction coefficients and available temperature-dependent physical properties. It is shown that predictions based on two different asperity models are never more than 60 C different. The Jaeger-Archard theory is modified to account for differences in subsurface temperature of the two bodies. The modified theory is used to show that the predicted total temperature is relatively insensitive to differences of about 15 percent in subsurface temperature. Under these circumstances, if the subsurface temperatures are assumed equal, the predicted total temperature is the maximum value attainable. Interpretation of the theory in the case where there are multiple junctions between the surfaces shows that for subsurface temperatures < 600 C the total temperat...
TL;DR: In this article, an investigation of the effects of various grinding fluids at both normal and high wheel speeds under geometrically similar conditions is described. But the results are limited to the case of a single wheel.
Abstract: An investigation is described of the lubricating effects of various grinding fluids at both normal and high wheel speeds under geometrically similar conditions. Grinding fluids include air (dry), water, soluble oil in two concentrations, and cutting oil. Results indicate that the specific cutting energy and the attritious wear of the abrasive grains are reduced by lubrication, but the rubbing friction between the workpiece and the wear flats on the grains is not. With high wheel speed, the specific cutting energy is lower with all grinding fluids than with normal wheel speed, but the attritious wear rate is greater. These lubricating effects are related to results for G-ratio, surface finish, and burning conditions. Presented at the 27th ASLE Annual Meeting in Houston, Texas, May 1–4, 1972
TL;DR: In this article, the free radical-induced high-temperature (to ca 370 C) oxidative degradation of polyphenyl ethers is shown to be drastically curtailed by the oxides, hydroxides and carbonates of the alkali metals and barium.
Abstract: The free radical-induced high-temperature (to ca 370 C) oxidative degradation of polyphenyl ethers is shown to be drastically curtailed by the oxides, hydroxides and carbonates (but not the neutral salts) of the alkali metals and barium. The inhibiting entities form colloidal or molecularly soluble complexes with the ether, and function in very low concentrations. Mechanisms are proposed which invoke either the basicity of the effective salts, or their ability to destroy peroxy radicals via superoxide formation. Properly designed inhibitors of the types discussed are of interest in polyphenyl ether-based lubricants for very-high-output aircraft turbine engines. Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE Lubrication Conference held in Pittsburgh, Pennsylvania, October 5–7, 1971
TL;DR: In this paper, the behavior of molybdenum disulphide adhering without any binder as a thin film on various metals and glass was studied under various temperatures and atmospheric pressures.
Abstract: Behavior under friction of molybdenum disulphide adhering without any binder as a thin film on various metals and glass was studied. Molybdenum disulphide film of up to about 1-micron thickness was formed by burnishing with sponge or by friction with metal. The friction and the life of the film were examined under various temperatures and atmospheric pressures. The endurance life is very affected by these factors. The micronization of the crystals was also observed and found to be affected by such factors. In vacuum the crystals are not micronized so severely as in air. The kind of the substrate material also has a marked influence on the life. The life of the film is longest with the pair of specimens made of f.c.c. noble metal. Presented at ASLE International Conference on Solid Lubrication, held in Denver, Colorado, August 24–27, 1971
TL;DR: In this article, a hydraulic squeeze bearing driven sinusoidally with the Navier-Stokes equation was proposed to improve the load capacity of a gas squeeze bearing under usual design conditions, provided cavitation is prevented.
Abstract: Prior researchers find that: Where one of two horizontal parallel plates immersed in a fluid is forced to oscillate up and down, a load may be carried, providing the fluid is compressible. Application of Reynolds equation to such a squeeze film bearing supports the condition of compressibility. However, analysis of the squeeze film bearing, including inertia terms in the Navier-Stokes equations, removes the restriction on compressibility. Theoretical design of a hydraulic squeeze bearing driven sinusoidally shows that load capacity is improved over a similar gas squeeze bearing under usual design conditions, provided cavitation is prevented. Two cases are considered of a fixed and a free bearing. Torque, work input, and the effects of centrifugal force are analysed. Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE Lubrication Conference held in Pittsburgh, Pennsylvania, October 5–7, 1971
TL;DR: In this paper, surface oxide, organic and lead film effects on friction and plastic deformation of Zn single crystal during sliding were studied and compared to surface oxide and lead films.
Abstract: Surface oxide, organic and lead film effects on friction and plastic deformation of Zn single crystal during sliding
TL;DR: In this paper, the effects of current on the lubricant properties of electrographite brushes running against slip rings of pure aluminium and stainless steel were examined. But the results of these experiments were discussed in terms of the surface topographical changes caused by the passage of current through the contact between the brushes and the slip rings.
Abstract: This paper describes experiments designed to examine the effects of current on the lubricant properties of electrographite brushes running against slip rings of pure aluminium and stainless steel. The range of current densities carried from 0 to 0.2 A.mm−2. It is shown that the effects of increasing current are generally beneficial in so far as friction and contact resistance are concerned. However, the wear of the brushes running on aluminium was unacceptably high. The results of these experiments are discussed in terms of the surface topographical changes (revealed by scanning electron microscopy) caused by the passage of current through the contact between the brushes and the slip rings. A mechanism of surface film breakdown with increasing current is postulated as a possible cause of the heavy wear of the brushes running on aluminium. Presented at ASLE International Conference on Solid Lubrication, held in Denver, Colorado, August 24–27, 1971
TL;DR: Injection-molded ASTM samples and test procedures were employed in gathering tooth strength, tensile strength, flexural strength, flexible modulus, heat distortion temperature, mold shrinkage, coefficient of thermal expansion, fatigue endurance, creep resistance, impact strength, PV limits, wear factor and coefficient of friction for a series of internally lubricated and glass-fortified thermoplastic resins.
Abstract: Injection-molded ASTM samples and test procedures will be employed in gathering tooth strength, tensile strength, flexural strength, flexural modulus, heat distortion temperature, mold shrinkage, coefficient of thermal expansion, fatigue endurance, creep resistance, impact strength, PV limits, wear factor and coefficient of friction for a series of internally lubricated and glass-fortified thermoplastic resins. Presented at ASLE International Conference on Solid Lubrication, held in Denver, Colorado, August 24–27, 1971
TL;DR: In this article, the problem of stable viscous flow of an incompressible fluid between two rotating nonconcentric cylinders is investigated and an approximate solution to the formulated problem is obtained by imposing a small gap restriction.
Abstract: Steady two dimensional viscous flow of an incompressible fluid between two rotating nonconcentric cylinders is investigated. The problem is formulated within the framework of a bipolar coordinate system. An approximate solution to the formulated problem is obtained by imposing a small gap restriction. The small gap velocity profiles and pressure distribution solution are employed to obtain some classical results of the journal bearing problem. Velocity profile and pressure curves are presented for speed ratios of 0.0, ± 1.0 and ± 2.0.
TL;DR: The development of antifriction materials based on lamellar solid lubricants dispersed as fillers in thermoplastic compounds is briefly reviewed in this paper, where experimental evidence is offered to account for the wide variations in friction and wear properties reported, in terms of flow orientation and cross-flow migration of the filler particles.
Abstract: The development of antifriction materials based on lamellar solid lubricants dispersed as fillers in thermoplastic compounds is briefly reviewed. Experimental evidence is offered to account for the wide variations in friction and wear properties reported, in terms of flow orientation and cross-flow migration of the filler particles. These findings confirm the importance of finish machining operations on the rubbing surfaces. Preliminary evidence is also offered for the disruption of particle orientation by polymer crystallization processes where the particles are small. Experimental methods used are: image analyzing microscopy, X-ray diffraction, and a specially developed friction testing machine for molded plastics samples. Presented at ASLE International Conference on Solid Lubrication, held in Denver, Colorado, August 24–27, 1971
TL;DR: In this article, the effect of axial vibration and bearing axial play in producing fretting damage in unlubricated ball bearings at constant temperature and humidity was investigated, and a simplified analog simulation model of the ball bearing and the vibration exciter system was also developed.
Abstract: An investigation was conducted to determine the effect of frequency and amplitude of axial vibration and of bearing axial play in producing fretting damage in unlubricated ball bearings at constant temperature and humidity. A study was also made of the impact forces occurring within the bearings due to these vibrations. A simplified analog simulation model of the ball bearing and the vibration exciter system was also developed. Frequency, amplitude, time, and a derived parameter GxI (the product of acceleration and impact frequency) had a very significant influence on fretting damage, indicated statistically at a confidence level of ninety-nine percent. Although axial play had little effect on fretting damage for the range of axial plays of the test bearings, it had significant effect on the acceleration levels obtained within the bearings. Fretting damage was measured with a bearing torque analyzer. The experimental test vibrations were accurately reproduced on the analog model. Presented as an American ...
TL;DR: In this article, a linearized analysis of a finite width rectangular step thrust bearing was performed and the dimensionless load capacity and stiffness were expressed in terms of a Fourier cosine series.
Abstract: A linearized analysis of a finite width rectangular step thrust bearing was performed. Dimensionless load capacity and stiffness are expressed in terms of a Fourier cosine series. The dimensionless load capacity and stiffness were found to be a function of the dimensionless bearing number Λ, the pad length-to-width ratio λ, the film thickness ratio κ, the step location parameter Ψ, and the feed groove parameter η. The equations obtained in the analysis were verified. The assumptions imposed were substantiated by comparison of the results with an existing exact solution for the infinite width bearing. A digital computer program was developed which determines optimal bearing configuration for maximum load capacity or stiffness. Simple design curves are presented. Results are shown for both compressible and incompressible lubrication. Through a parameter transformation the results are directly usable in designing optimal step sector thrust bearings. Presented at the 26th ASLE Annual Meeting in Boston, Massac...