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An analytical investigation of cylindrical roller bearings having annular rollers
SYSTEMATIC
ABSTRACTS
OF CURRENT LITERATURE
This paper includes the predominant centripetal inertia terms in a comprehensive analysis of hydrostatic thrust bearings of spherical form. The analysis considers continuous spherical surfaces which are not interrupted by grooves and solutions are presented for spheres having radii equal to and less than the radius of the hemispherical seat. This analysis demonstrates that fluid inertia effects influence the pressure distribution as suggested by Shaw and Strang. When the sphere and seat have equal radii the film pressures are always enhanced while for the other case the film pressures may increase or decrease depending upon the location of the center of the hemispherical seat. Attention is drawn to the main characteristics of this form of bearing which is capable of supporting combined axial and radial loads. A Re-Examination of Hydrosphere Perforrnante. D. Downson and C. M. Taylor, ASLE Trans., 10 (1967) 325-333. This paper considers the performance of the spherical thrust bearing, known as the hydrosphere. The analytical and experimental work of Shaw and Strang is examined and experimental results presented to substantiate the authors’ own inertia theory presented in their previous paper. The paper demonstrates that inertia action could not account for the performance of the hydrosphere tested by Shaw and Strang. Various other factors, such as thermal effects on the lubricant and differential expansion of the bearing solids, are examined to see if they could account for the known performance of Shaw and Strang’s bearing. Finally, the authors conclude that the most likely factor to explain the observed results is thermal expansion of the bearing lands between the grooves. The Externally-pressurized, Porous-wall, Gas-lubricated Journal Bearing. H. J. Sneck and K. T. Yen, ASLE Trans., IO (w67)
339-347.
Previous studies in this series have investigated analytically and experimentally the performance characteristics of nonrotating porous journal bearings. In this paper the effects of rotation are analyzed for operation at small eccentricity ratios and also for operation at very large speed parameters. Shaft rotation is found to have a generally beneficial effect on the flow-rate requirements and load carrying capacity. Thermally Activated Seizure of Angular Contact Bearings. R. A. Burton and H. E. Staph, ASLE Trans., IO (1967) 408-417. Equations have been developed relating
391
friction-power to bearing element temperatures for the particular case of prelubricated or lightly lubricated ball bearings. An expression is derived for the change in relative dimensions of an angular contact bearing, as determined by the temperature gradient across the bearing. A second expression is found for the accommodation of the bearing to expansion, this accommodation resulting from elastic deformation and changes in contact angles. A comparison of these relationships reveals that unstable operating conditions may occur and lead to sudden uncontrollable increases in contact loads. These regions of unstable operation may occur as a result of lubricant degradation or bearing wear, as well as combinations of operating speed and housing dimensions. An Analytical Investigation of Cylindrical Roller Bearings Having Annular Rollers. T. A. Harris and S. F. Aaronson, ASLE Trans., IO (1967) 235-242. Turbulent Operation of the Visco Seal. H. N. Ketola and J. M. McGrew, ASLE Trans., IO (1967) 256-272.
.j. MATERIALS
AND
WEAR
Size Reduction. R. H. Snow and L. T. Work, Id. Eng. Chew., 59 (II) (1967) 80-85; 2 figs., 77 refs.The customary flood of new equipment in the _ _ literature is accompanied by more fundamental studies of solid fracture and by kinetic modeling of grinding processes. The Wear of Oxide Ceramics under the Influence of Surface-active Substances. (in German) B. Frisch, Ber. Deut. Keram. Ges., 44 (1967) 584-591; 12 figs., 31 refs. Sintered or-alumina was ground in a container performing a reciprocating rotary motion using solutions of surface-active substances in benzene. By suitable experimentation it is possible to adjust the abrasion process from pure body-abrasion to grinding of particles. Simultaneous use of several samples leads to a good reproducibility of the results. The dependence of the rate of grinding on both diameter of the specimen and circumferential sueed of rotation is used to explain the mechanism of the sliding rolling wear. Although the rate of grinding is increased by additions of surface-active substances (propionic, caproic, palmitic acids, butanol and acetone) the activation energy of the grinding process does not depend on the adsorption of surfaceactive agents. Diagrams for rates of grinding are given ranging from pure body-againstbody abrasion to one in which particle Wear,
II
(1968)
ABSTRACTS
OF CURRENT LITERATURE
This paper includes the predominant centripetal inertia terms in a comprehensive analysis of hydrostatic thrust bearings of spherical form. The analysis considers continuous spherical surfaces which are not interrupted by grooves and solutions are presented for spheres having radii equal to and less than the radius of the hemispherical seat. This analysis demonstrates that fluid inertia effects influence the pressure distribution as suggested by Shaw and Strang. When the sphere and seat have equal radii the film pressures are always enhanced while for the other case the film pressures may increase or decrease depending upon the location of the center of the hemispherical seat. Attention is drawn to the main characteristics of this form of bearing which is capable of supporting combined axial and radial loads. A Re-Examination of Hydrosphere Perforrnante. D. Downson and C. M. Taylor, ASLE Trans., 10 (1967) 325-333. This paper considers the performance of the spherical thrust bearing, known as the hydrosphere. The analytical and experimental work of Shaw and Strang is examined and experimental results presented to substantiate the authors’ own inertia theory presented in their previous paper. The paper demonstrates that inertia action could not account for the performance of the hydrosphere tested by Shaw and Strang. Various other factors, such as thermal effects on the lubricant and differential expansion of the bearing solids, are examined to see if they could account for the known performance of Shaw and Strang’s bearing. Finally, the authors conclude that the most likely factor to explain the observed results is thermal expansion of the bearing lands between the grooves. The Externally-pressurized, Porous-wall, Gas-lubricated Journal Bearing. H. J. Sneck and K. T. Yen, ASLE Trans., IO (w67)
339-347.
Previous studies in this series have investigated analytically and experimentally the performance characteristics of nonrotating porous journal bearings. In this paper the effects of rotation are analyzed for operation at small eccentricity ratios and also for operation at very large speed parameters. Shaft rotation is found to have a generally beneficial effect on the flow-rate requirements and load carrying capacity. Thermally Activated Seizure of Angular Contact Bearings. R. A. Burton and H. E. Staph, ASLE Trans., IO (1967) 408-417. Equations have been developed relating
391
friction-power to bearing element temperatures for the particular case of prelubricated or lightly lubricated ball bearings. An expression is derived for the change in relative dimensions of an angular contact bearing, as determined by the temperature gradient across the bearing. A second expression is found for the accommodation of the bearing to expansion, this accommodation resulting from elastic deformation and changes in contact angles. A comparison of these relationships reveals that unstable operating conditions may occur and lead to sudden uncontrollable increases in contact loads. These regions of unstable operation may occur as a result of lubricant degradation or bearing wear, as well as combinations of operating speed and housing dimensions. An Analytical Investigation of Cylindrical Roller Bearings Having Annular Rollers. T. A. Harris and S. F. Aaronson, ASLE Trans., IO (1967) 235-242. Turbulent Operation of the Visco Seal. H. N. Ketola and J. M. McGrew, ASLE Trans., IO (1967) 256-272.
.j. MATERIALS
AND
WEAR
Size Reduction. R. H. Snow and L. T. Work, Id. Eng. Chew., 59 (II) (1967) 80-85; 2 figs., 77 refs.The customary flood of new equipment in the _ _ literature is accompanied by more fundamental studies of solid fracture and by kinetic modeling of grinding processes. The Wear of Oxide Ceramics under the Influence of Surface-active Substances. (in German) B. Frisch, Ber. Deut. Keram. Ges., 44 (1967) 584-591; 12 figs., 31 refs. Sintered or-alumina was ground in a container performing a reciprocating rotary motion using solutions of surface-active substances in benzene. By suitable experimentation it is possible to adjust the abrasion process from pure body-abrasion to grinding of particles. Simultaneous use of several samples leads to a good reproducibility of the results. The dependence of the rate of grinding on both diameter of the specimen and circumferential sueed of rotation is used to explain the mechanism of the sliding rolling wear. Although the rate of grinding is increased by additions of surface-active substances (propionic, caproic, palmitic acids, butanol and acetone) the activation energy of the grinding process does not depend on the adsorption of surfaceactive agents. Diagrams for rates of grinding are given ranging from pure body-againstbody abrasion to one in which particle Wear,
II
(1968)