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Friction characteristics of automatic transmission fluids as related to transmission operation
SYSTEMATIC
321
ABSTRACTS
Systematic Abstracts of Current
Literature
Selected from the literature and from Battelle Technical
Review
1961
I. DEFORMATIONAND FRACTURE (no abstracts) 2. FRICTION OsciUating Tangential Forces on Cylindrical Specimens in Contact at Displacements within the Region of No Gross Slip. R. V. Klint. ASLE Trans., 3 (2) (1960) 255264; II figs., 2 tables, 16 refs. The effects of oscillating tangential forces on cylindrical specimens at relative displacements within the no-gross-slip region have been studied experimentally. It is shown that within the no-gross-slip region there is a well-defined region at the onset of tangential displacement within which a primarily elastic deformation is indicated. Energy dissipation studies indicate that in this region the behavior is essentially visco-elastic, confirming the results of published work. This “limit of elastic behavior” has been found and measured for a number of metallic and non-metallic materials including diamond and plastics. At amplitudes below this limit no discernable wear is observed, even after millions of cycles of rubbing. However, at larger amplitudes, wear is rapid and characteristic of fretting corrosion, especially above the gross slip amplitude. Values of elastic tangential compliance at the limit of elastic behavior are determined which are in agreement with published theoretical work. A Note on the Influence of Elastic Compliance on Sliding Friction in Ball Bearings. K. L. Johns0n.j. Basic Eng., (ASME, Trans. Ser. D), 82 (4) (1960) Bgg-goo. Short discussion on effect of tangential compliance on the friction moment resisting the motion of a ball which is spinning while rolling. Theoretical and Experimental Investigations on the Pressure Loss in Pneumatic Conveyors with Special Regard to the Influence of Friction and Weight of Materials to be Conveyed. (in German) E. Muschelknautz. VDI-Forschungsheft, 25 (1959) 476 (32 pp.). For detailed abstract see Appl. Mechanics Revs., 14 (1961) 160. The principal experimental section gives detailed observations of forces and velocities
involved in the impact of granular solids on rotating metal disks. Friction coefficients are deduced for a number of particle and surface materials used in conveying practice. Finally, a wide range of published and unpublished measurements on the horizontal conveying of wheat, mine tailings, quartz, Carborundum and glass-spheres is examined in the light of the foregoing. Friction factor and particle/gas velocity ratio are expressed in terms of Froude numbers based on gas and particle terminal velocities respectively. In general, two regimes can be distinguished; at large gas velocities, wall friction predominated and friction factor is fairly constant; at low gas velocities, gravity effects predominate and friction factor rises steeply. An Investigation of the Stressed State of the Surface Layers of Rubbing Bodies during Sliding with Change of Sign. (in Russian)
K. V. Savitskii and Yu. P. Geraskevich. Fiz. Meta1.i Metalloved. Akad. NaukS.S.S.R., 4 (3) (1957) 519-526; ref. Zhur. Mekh., no. 3 (1959) ; source Appl. Mechanics Revs., 14 (1961) 78. This is an investigation of the nature of the cold-hardening of the surface layers and the thermal stability of the deformed distortions which are observed in one-sided sign-changing friction of iron, copper, aluminium and duralumin samples. The microhardness of the samples wasdetermined, to serve as a standard for the extent of l$ardening attributable to deformation. It was shown that the contact surfaces harden to a greater extent when the friction is in one direction than when the friction is variable in direction. This can be explained by the fact that some of the less stable deformation distortions are apt to level out. Friction Characteristics of Automatic Transmission Fluids as Related to Transmission Operation. Merrill L. Haviland and John J. Rodgers. Lubrication Eng., 17 (3) (1961) rro-117; II figs., I table, IO refs. Shift performance in automatic transmissions Wear, 4 (1961) 321-330
has been found to be related to the frictional qualities of transmission fluids. This relationship has been studied in two types of alipar&us : one a full-scale transmission set-up and the other a bench apparatus. In full-scale transmissions, fluids were evaluated with respect to shift performance, severity of stick-slip, and oxidation resistance. Shift performance and severity of stick-slip were dctcrmincd by analysis of recorded variables such as output shaft torque and engine speed as functions of time. Hy measuring fluid acidity periodically during each investigation an interrelationship between
fluid oxidation r-esistance an(l stick-slip \\A‘found. In the bench apparatus, m(asurcments OI friction as a function of sliding slxxd wcr( made with load and fluid temperature as parameters. These measurements were made not only with new fluids but also with fluids conditioned by transmission use. .\ corrcl;ttion was found between fluid pcrformancc in a transmission and the friction characteristics determined in the bench apparatus. On the basis of the fluid friction characteristics lx~i-tinent comments arc made regarding the friction mechanism.
3.1. Lubricatiou
author obtains the generalized differential equation of a variable ?I upon which pressure distribution, as well as other characteristics, depends. This equationisintegrated in the case of two-dimensional motion ; as an application, the problem of plane surfaces and constant viscosity is discussed and it is shown that parameter K = 6 VP, I//? h22(hi/hzPr) has an important influence. For circular cylindrical surfaces, the density depends on an integral expression the solution of which is obtained by means of conventional graphical and numerical computations. Finally on the basis of the assumption that the viscosity also varies with pressure, a general method is given for solving the twodimensional problem.
Problems
of Lubrication
M. M. Freundlich cation
Eng.,
in Space.
and C. H. Hannan. Lubvi1961) 72-77; 7 figs.,
17 (2) (Feb.
z tables, I ref. With the aim of operating eventually small motors in space for a period of over a year, the authors have collected a large number of standard or experimental oils and greases and have tested them in three phases. In the first phase, they eliminated the lubricants with the highest evaporation rates in tests in a vacuum of IO.-~ mm Hg. The fifteen best of these were finally tested as lubricants in R-r size bearings in motors operating at 4000 rev/ min in a vacuum of 10-s mm Hg. After IOOO hours of operation, an inspection of the disassembled bearings showed that several oils and oil and grease combinations had deteriorated during these tests to such a slight extent that it can be assumed that they would have operated for a considerably longer time had the tests been continued. Gear Lubrication. Part I. (in German) Getriebeschmierung A. A. Bartel. VDI Zeitschvift, 103 (6) (1961) 251-264; 12 figs., 5 tables, 91 refs. Survey on recent progress on the above field with special reference to gas lubrication and heavy duty liquid lubrication. A classification is given of different types of damage to gearing. Detailed discussions on the influence of pressure as related to structure of lubricating liquids. The practical consequences of present knowledge are reviewed. Effects of Fluid Film dynamic Lubrication. N. Tipei. ASLE Trans., 4 figs., 4 refs.
Pressure
on Hydro-
3 (2) (1960)
277-280:
The effect of pressure upon hydrodynamic lubrication is reflected by the variation of the density and viscosity of the lubricant. Proceeding from the function that relates density to pressure in the case of liquids, the
Flow Properties of Lithium Stearate-Oil Model Greases as Functions of Soap Concentration and Temperature.
Walther H. Rauer, .4lfred I’. Finkelstein and Stephen E. Wiberley. ASLE Trans., 3 (r) (1960) 2r5mm~24; II figs., 3 tables, 13 refs. Lithium stcaratc-oil greases having 4. 8, and I LT/, soap were prepared and flow properties of the greases were investigated, at 0.25 and 37.8 ‘C. Flow data were obtained with a cone and plate viscometer equipped with automatic programming and recording of shear stress UL’YSUS rate of shear, and of shear stress z)wsus time at selected shear rates. Flow curves, shear stress Z~~YSUS shear rate, were obtained for an initial and a repeat 3oo-set cycle of shear with maxima of 1520 set-i and of r5,zoo SK 1. Flow curves were measured fothighly worked samples, previously sheared at 19,000 set-* for IOOOsec. The rate of change of shearing stress required to maintain a constant rate of shear was measured at nine shear rates in the interval from 190 set-i to 19,000 see-*. Similar flow measurements were made on greases containing stearic acid additives. Initial flow resistance, ascribed to soap structural elements, showed temperature and concentration dependence differing from that of the sheared soap, and was destroyed
321
ABSTRACTS
Systematic Abstracts of Current
Literature
Selected from the literature and from Battelle Technical
Review
1961
I. DEFORMATIONAND FRACTURE (no abstracts) 2. FRICTION OsciUating Tangential Forces on Cylindrical Specimens in Contact at Displacements within the Region of No Gross Slip. R. V. Klint. ASLE Trans., 3 (2) (1960) 255264; II figs., 2 tables, 16 refs. The effects of oscillating tangential forces on cylindrical specimens at relative displacements within the no-gross-slip region have been studied experimentally. It is shown that within the no-gross-slip region there is a well-defined region at the onset of tangential displacement within which a primarily elastic deformation is indicated. Energy dissipation studies indicate that in this region the behavior is essentially visco-elastic, confirming the results of published work. This “limit of elastic behavior” has been found and measured for a number of metallic and non-metallic materials including diamond and plastics. At amplitudes below this limit no discernable wear is observed, even after millions of cycles of rubbing. However, at larger amplitudes, wear is rapid and characteristic of fretting corrosion, especially above the gross slip amplitude. Values of elastic tangential compliance at the limit of elastic behavior are determined which are in agreement with published theoretical work. A Note on the Influence of Elastic Compliance on Sliding Friction in Ball Bearings. K. L. Johns0n.j. Basic Eng., (ASME, Trans. Ser. D), 82 (4) (1960) Bgg-goo. Short discussion on effect of tangential compliance on the friction moment resisting the motion of a ball which is spinning while rolling. Theoretical and Experimental Investigations on the Pressure Loss in Pneumatic Conveyors with Special Regard to the Influence of Friction and Weight of Materials to be Conveyed. (in German) E. Muschelknautz. VDI-Forschungsheft, 25 (1959) 476 (32 pp.). For detailed abstract see Appl. Mechanics Revs., 14 (1961) 160. The principal experimental section gives detailed observations of forces and velocities
involved in the impact of granular solids on rotating metal disks. Friction coefficients are deduced for a number of particle and surface materials used in conveying practice. Finally, a wide range of published and unpublished measurements on the horizontal conveying of wheat, mine tailings, quartz, Carborundum and glass-spheres is examined in the light of the foregoing. Friction factor and particle/gas velocity ratio are expressed in terms of Froude numbers based on gas and particle terminal velocities respectively. In general, two regimes can be distinguished; at large gas velocities, wall friction predominated and friction factor is fairly constant; at low gas velocities, gravity effects predominate and friction factor rises steeply. An Investigation of the Stressed State of the Surface Layers of Rubbing Bodies during Sliding with Change of Sign. (in Russian)
K. V. Savitskii and Yu. P. Geraskevich. Fiz. Meta1.i Metalloved. Akad. NaukS.S.S.R., 4 (3) (1957) 519-526; ref. Zhur. Mekh., no. 3 (1959) ; source Appl. Mechanics Revs., 14 (1961) 78. This is an investigation of the nature of the cold-hardening of the surface layers and the thermal stability of the deformed distortions which are observed in one-sided sign-changing friction of iron, copper, aluminium and duralumin samples. The microhardness of the samples wasdetermined, to serve as a standard for the extent of l$ardening attributable to deformation. It was shown that the contact surfaces harden to a greater extent when the friction is in one direction than when the friction is variable in direction. This can be explained by the fact that some of the less stable deformation distortions are apt to level out. Friction Characteristics of Automatic Transmission Fluids as Related to Transmission Operation. Merrill L. Haviland and John J. Rodgers. Lubrication Eng., 17 (3) (1961) rro-117; II figs., I table, IO refs. Shift performance in automatic transmissions Wear, 4 (1961) 321-330
has been found to be related to the frictional qualities of transmission fluids. This relationship has been studied in two types of alipar&us : one a full-scale transmission set-up and the other a bench apparatus. In full-scale transmissions, fluids were evaluated with respect to shift performance, severity of stick-slip, and oxidation resistance. Shift performance and severity of stick-slip were dctcrmincd by analysis of recorded variables such as output shaft torque and engine speed as functions of time. Hy measuring fluid acidity periodically during each investigation an interrelationship between
fluid oxidation r-esistance an(l stick-slip \\A‘found. In the bench apparatus, m(asurcments OI friction as a function of sliding slxxd wcr( made with load and fluid temperature as parameters. These measurements were made not only with new fluids but also with fluids conditioned by transmission use. .\ corrcl;ttion was found between fluid pcrformancc in a transmission and the friction characteristics determined in the bench apparatus. On the basis of the fluid friction characteristics lx~i-tinent comments arc made regarding the friction mechanism.
3.1. Lubricatiou
author obtains the generalized differential equation of a variable ?I upon which pressure distribution, as well as other characteristics, depends. This equationisintegrated in the case of two-dimensional motion ; as an application, the problem of plane surfaces and constant viscosity is discussed and it is shown that parameter K = 6 VP, I//? h22(hi/hzPr) has an important influence. For circular cylindrical surfaces, the density depends on an integral expression the solution of which is obtained by means of conventional graphical and numerical computations. Finally on the basis of the assumption that the viscosity also varies with pressure, a general method is given for solving the twodimensional problem.
Problems
of Lubrication
M. M. Freundlich cation
Eng.,
in Space.
and C. H. Hannan. Lubvi1961) 72-77; 7 figs.,
17 (2) (Feb.
z tables, I ref. With the aim of operating eventually small motors in space for a period of over a year, the authors have collected a large number of standard or experimental oils and greases and have tested them in three phases. In the first phase, they eliminated the lubricants with the highest evaporation rates in tests in a vacuum of IO.-~ mm Hg. The fifteen best of these were finally tested as lubricants in R-r size bearings in motors operating at 4000 rev/ min in a vacuum of 10-s mm Hg. After IOOO hours of operation, an inspection of the disassembled bearings showed that several oils and oil and grease combinations had deteriorated during these tests to such a slight extent that it can be assumed that they would have operated for a considerably longer time had the tests been continued. Gear Lubrication. Part I. (in German) Getriebeschmierung A. A. Bartel. VDI Zeitschvift, 103 (6) (1961) 251-264; 12 figs., 5 tables, 91 refs. Survey on recent progress on the above field with special reference to gas lubrication and heavy duty liquid lubrication. A classification is given of different types of damage to gearing. Detailed discussions on the influence of pressure as related to structure of lubricating liquids. The practical consequences of present knowledge are reviewed. Effects of Fluid Film dynamic Lubrication. N. Tipei. ASLE Trans., 4 figs., 4 refs.
Pressure
on Hydro-
3 (2) (1960)
277-280:
The effect of pressure upon hydrodynamic lubrication is reflected by the variation of the density and viscosity of the lubricant. Proceeding from the function that relates density to pressure in the case of liquids, the
Flow Properties of Lithium Stearate-Oil Model Greases as Functions of Soap Concentration and Temperature.
Walther H. Rauer, .4lfred I’. Finkelstein and Stephen E. Wiberley. ASLE Trans., 3 (r) (1960) 2r5mm~24; II figs., 3 tables, 13 refs. Lithium stcaratc-oil greases having 4. 8, and I LT/, soap were prepared and flow properties of the greases were investigated, at 0.25 and 37.8 ‘C. Flow data were obtained with a cone and plate viscometer equipped with automatic programming and recording of shear stress UL’YSUS rate of shear, and of shear stress z)wsus time at selected shear rates. Flow curves, shear stress Z~~YSUS shear rate, were obtained for an initial and a repeat 3oo-set cycle of shear with maxima of 1520 set-i and of r5,zoo SK 1. Flow curves were measured fothighly worked samples, previously sheared at 19,000 set-* for IOOOsec. The rate of change of shearing stress required to maintain a constant rate of shear was measured at nine shear rates in the interval from 190 set-i to 19,000 see-*. Similar flow measurements were made on greases containing stearic acid additives. Initial flow resistance, ascribed to soap structural elements, showed temperature and concentration dependence differing from that of the sheared soap, and was destroyed