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The lubrication of gears operating under unusual conditions
I ITERATURE
AND CURRENT
EVENTS
ed in the PYOC. Imt. Me& Engm., London, rp6qjrg65; 8 figs., 2 tables, o refs. There are various factors limiting the loadcarrying capacity of a steadily-loaded journal bearing operating under hydrodynamic conditions. Two of these factors are considered. (I) Surface finish criterion: Bearing and journal surfaces are slightly grooved due to machining processes, and when initial contact is made between the surfaces, it is only made at local high peaks, leaving an idealized effective hydrodynamic oil film at the minimum film thickness position in the bearing. This minimum film thickness at metal-tometal contact conditions is dependent on the surface finish of the two mating surfaces. (2) White-metat &p&g criterion: At highspeed operation, the oil film temperature in the region of the minimum oil film position will be high if the bearing is operating with a large eccentricity. A condition can arise where the oil film temperature is sufficiently high to cause local plastic flow of the bearing white metal. This criterion is known as “wiping”, and at high speeds it will predominate over the surface finish criterion. These two criteria are used in an analysis which gives guidance to the minimum allowable oil film thickness for journals of various sizes running at various speeds. This gives the bearing designer, using conventional hydrodynamic theory (Ocvirk, Cameron and Wood, etc.), some yardstick to assess whether or not his calculated minimum oil film thickness figures are satisfactory.
I47 on-line computing equipment. Defining electrical contacts as asperity approaches through a separating film, the average duration and frequency of such approaches is computed from surface microgeometry statistics. A comparison of computed and observed values of contact conductivity parameters shows good order of magnitude agreement and yields estimates of average film thickness as a function of speed and load which agree satisfactorily with the order of film thickness predicted by elastohydrodynamic theory. Significant wear is shown to occur only in regimes where the film is interrupted and to become progressively more rapid as the severity of asperity contacts increases with decreasing speed. The Lubrication of Gears Operating Under Unusual Conditions. H. J. Watson, Second Convention on Lubrication and Wear, 1964, Paper IO. To be published in the Proc Inst. Much. Engrs., London, 19641 1965; 8 figs., 8 tables, 8 refs. 3.2. Liquid
Lubricants
Effects of Two-dimensional, Sinusoidal Roughness on the Load Support Characteristics of a Lubricant Film. R. A. Burton, J. Basic Eng., .z (1963) 258264. An attempt is made in this paper to analyze mathematically some effects of boundary roughness on the characteristics of lubricant films. To simplify the complex problem many assumptions, other than the usual ones, are made and the analysis is restricted to an idealized sinusoidal form of roughness.
Chemical and Mechanical Characteristics of a Deep-dewaxed Mineral Oil Hydraulic Fluid. V. Hopkins et aI., ASLE Trans., 7 (1964) 186; g figs., 7 tables, 6 refs. This paper is a reasonably complete presentation of the formulation, the physical and chemical properties, and the pump loop behavior of a deep-dewaxed mineral oil, ML0 6o-294. Properties given include : (a) viscosity and bulk modulus as functions of both temperature and pressure, (b) specific heat, density, thermal expansion, vapor pressure, and thermal conductivity as functions of temperature, and (c) pour, cloud, flash, and fire points. The behavior of this fluid in one pump loop to 700”F, and in a second loop to 6oo”F, is discussed. Excellent fluid performance was obtained in these pump loops at 400, 500, 550, and 600°F; however, the fluid degraded rapidly at 7oo’F.
Lubricant Films in Rolling Contact of Rough Surfaces. T. E. Tallian et al., ASLE Trans., 7 (2) (‘964) rag-126; 18 figs., 2 tables, 18 refs. An experimental and mathematical study of elastohydrodynamic film formation is described for a rolling four-ball configuration utilizing steel bearing balls. Wear rates are determined in the microgram range, using a radiotracer tagged ball. Existence and intcrruptions of elastohydrodynamic films are observed by measurement of electrical conductivity through the Hertzian contact. Surface microgeometry of the rolling tracks on the balls is statistically analyzed by processing electrical analogs of surface profiles through
Radiotracers Reveal Activity of Extretnepressure Additives in Lubrication. A. A. Manteuffel et al., ASLE Trans., 7 (1964) 249: 13 figs., 2 refs. The mechanism of extreme-pressure (EP) lubrication has been studied with various approaches in a number of laboratories over the past years. An investigation in this area was initiated recently in this laboratory with a modified four-ball tester [Manteuffel and Wolfram, ASLE Trans., 3, p. 1571 wherein the lubricant temperature leaving the ball interfaces is recorded as the load is continuously increased. The patterns of the temperatureload curves generated under these conditions are dependent on the lubricant compositions. Weau, 8 (1965) 143-155
AND CURRENT
EVENTS
ed in the PYOC. Imt. Me& Engm., London, rp6qjrg65; 8 figs., 2 tables, o refs. There are various factors limiting the loadcarrying capacity of a steadily-loaded journal bearing operating under hydrodynamic conditions. Two of these factors are considered. (I) Surface finish criterion: Bearing and journal surfaces are slightly grooved due to machining processes, and when initial contact is made between the surfaces, it is only made at local high peaks, leaving an idealized effective hydrodynamic oil film at the minimum film thickness position in the bearing. This minimum film thickness at metal-tometal contact conditions is dependent on the surface finish of the two mating surfaces. (2) White-metat &p&g criterion: At highspeed operation, the oil film temperature in the region of the minimum oil film position will be high if the bearing is operating with a large eccentricity. A condition can arise where the oil film temperature is sufficiently high to cause local plastic flow of the bearing white metal. This criterion is known as “wiping”, and at high speeds it will predominate over the surface finish criterion. These two criteria are used in an analysis which gives guidance to the minimum allowable oil film thickness for journals of various sizes running at various speeds. This gives the bearing designer, using conventional hydrodynamic theory (Ocvirk, Cameron and Wood, etc.), some yardstick to assess whether or not his calculated minimum oil film thickness figures are satisfactory.
I47 on-line computing equipment. Defining electrical contacts as asperity approaches through a separating film, the average duration and frequency of such approaches is computed from surface microgeometry statistics. A comparison of computed and observed values of contact conductivity parameters shows good order of magnitude agreement and yields estimates of average film thickness as a function of speed and load which agree satisfactorily with the order of film thickness predicted by elastohydrodynamic theory. Significant wear is shown to occur only in regimes where the film is interrupted and to become progressively more rapid as the severity of asperity contacts increases with decreasing speed. The Lubrication of Gears Operating Under Unusual Conditions. H. J. Watson, Second Convention on Lubrication and Wear, 1964, Paper IO. To be published in the Proc Inst. Much. Engrs., London, 19641 1965; 8 figs., 8 tables, 8 refs. 3.2. Liquid
Lubricants
Effects of Two-dimensional, Sinusoidal Roughness on the Load Support Characteristics of a Lubricant Film. R. A. Burton, J. Basic Eng., .z (1963) 258264. An attempt is made in this paper to analyze mathematically some effects of boundary roughness on the characteristics of lubricant films. To simplify the complex problem many assumptions, other than the usual ones, are made and the analysis is restricted to an idealized sinusoidal form of roughness.
Chemical and Mechanical Characteristics of a Deep-dewaxed Mineral Oil Hydraulic Fluid. V. Hopkins et aI., ASLE Trans., 7 (1964) 186; g figs., 7 tables, 6 refs. This paper is a reasonably complete presentation of the formulation, the physical and chemical properties, and the pump loop behavior of a deep-dewaxed mineral oil, ML0 6o-294. Properties given include : (a) viscosity and bulk modulus as functions of both temperature and pressure, (b) specific heat, density, thermal expansion, vapor pressure, and thermal conductivity as functions of temperature, and (c) pour, cloud, flash, and fire points. The behavior of this fluid in one pump loop to 700”F, and in a second loop to 6oo”F, is discussed. Excellent fluid performance was obtained in these pump loops at 400, 500, 550, and 600°F; however, the fluid degraded rapidly at 7oo’F.
Lubricant Films in Rolling Contact of Rough Surfaces. T. E. Tallian et al., ASLE Trans., 7 (2) (‘964) rag-126; 18 figs., 2 tables, 18 refs. An experimental and mathematical study of elastohydrodynamic film formation is described for a rolling four-ball configuration utilizing steel bearing balls. Wear rates are determined in the microgram range, using a radiotracer tagged ball. Existence and intcrruptions of elastohydrodynamic films are observed by measurement of electrical conductivity through the Hertzian contact. Surface microgeometry of the rolling tracks on the balls is statistically analyzed by processing electrical analogs of surface profiles through
Radiotracers Reveal Activity of Extretnepressure Additives in Lubrication. A. A. Manteuffel et al., ASLE Trans., 7 (1964) 249: 13 figs., 2 refs. The mechanism of extreme-pressure (EP) lubrication has been studied with various approaches in a number of laboratories over the past years. An investigation in this area was initiated recently in this laboratory with a modified four-ball tester [Manteuffel and Wolfram, ASLE Trans., 3, p. 1571 wherein the lubricant temperature leaving the ball interfaces is recorded as the load is continuously increased. The patterns of the temperatureload curves generated under these conditions are dependent on the lubricant compositions. Weau, 8 (1965) 143-155