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Mechanical elements for vacuum operation
LITERATIJRB
250
ANT, CURRENT
including molybclmum disulphidc, is influenced be- the nature of the base lulrricant and the compstability of the additives. Water in oil has a detrimental effect which ran Ix counteracted by additivrs. lnvestigaadditives,
3. T.uRRrcnrroN A Model Experiment in Elasto-Hydrodynamic Lubrication. G, R. Higginson, Intwz. J. Mpch. Sci., 4 (1962) 205-2’0; A$$. Mpch. Rev., r6 (2) (1963) 173, no. 1310. Fuel and Lubricant Requirements of Modern High Output Two-stroke Cycle Outboard Motors. G. H. Millar and 13. Carlson, Lubrication Eng., 19 (1) (1963) 21~-27; 12 fig., I ref. Effect of Surface Coatings on the Load Carrying Capacity of Steel. G. F. Wolfe, Lubricalion Eng., ry (I) (1963) 28-35; 2 fig., 9 tables, 11 refs. The effect of various surface coatings on improving the load carrying and anti-wear characteristics of steel in silicone, dies&, and petroleum oils is presented. Data were obtained using the Falex machine, a roll tester, and a gear test stand. The surface coatings evaluated included metal plates, banded solid lubricants, flame sprayed coatings, salt bath treatments, and electric spark metal deposition. The resutts indicate that whenever the combination of steel sliding on steel is broken up, an improvement in load carrying capacity and anti-wear properties is obtained. Soft metal pIatcs and metals with low melting points improve the load carrying ability of steel in all oils. Silver plate is very effective. Diffusion processes which produce a definite case layer on steel also provide very satisfactoryseizureandanti-wearproperties. Several processes outperform conventional nitriding and carburizing. The most promising surface coatings should be considered for applications where increased load carrying ability or operation in unusual environments is required. Engineering applications of such coatings will. of course, depend on a full analysis of all the operating conditions as well as the particular characteristics of any specific surface.
EVENTS
tion by radio-active tracer technique has shotvn that accclcrated failure in the prescnct of water- may be due to hydrogen cmbrittll:ment.
AND LrrBRrcaNrs Physical and Chemical Properties of Complex Soap Greases. A. T. l’olishuk, Lz&icration fing., rp (2) (7963) 76.. 87; 16fig., 12 tables, 72 refs. The properties of soap particles and fibers characterize the structure and physical pmperties of their greases. But the chemistry of the soap molecule itself is the most significant factor. It is especially useful in defining complcx soap grcascs. It is suggested that cornl’lex soap greases be defined as those which are formed when two dissimilar acids arr attached to the same molecule. By this definition, only polyvalcnt elements can form true complex soaps. Complex soap greases arc among the best, currently available, multipurpose lubricants. The most commonly used complex greases arc those of calcium and barium soaps, yet they seem to offer little advantage over conventional lithium multipurpose greases. They have higher dropping points, and some calcium complexes offer built-in EP properties, but they have poor reversibility and dispensability characteristics. Barium complexes require high soap contents and are costly. Aluminum complex greases arc the best of the complex greases. They have excellent pumpabilitv characteristics, good mechanical and oxidation stability, and outstanding rcsistance to oil separation when subjcctcd to pressure and/or tcmpcraturc. Wear and Corrosion Tendencies of Molybdenum Disulfide~Contaiuing Greases. S. F. Calhoun, Tech. Rept., (1962) 13 pp., 19 refs., Sci. and Tech. .4crospace Repts., 1 (2) (1963) III. The tendency of molybdenum disulfide to increase the wear of greases is shown by results of laboratory tests. The extreme pressure properties of greases were increased by the addition of the molybdenum disulfide. It also promotes rusting of ferrous metals when added to grease.
4. MACHINE PARTS 4.x Mechanical
ditions
Elements
under Entveme
Con-
MechanicalElementsforVacuumOperation. H. E. Evans, T. W. Flately and M. Francis Federline, Sci. and Tech. Aerospace Rep&., I (3) (1963) 182. N 63-11278, NASA;Presented at the ARS 17th Ann. Meeting and Space
Flight Exposition, Los Angeles, Nov. 13-18, 1962 ; (ARS Paper 2711-62) 12 pp. The first two phases of a program investigating the high-speed operation of miniature ball bearings with metallic film lubrication and the first phase of an investigation for determining the “best bet” gear material combinations
SYSTEMATIC ABSTRACTS and methods of lubrication are included. Results of the bearing study indicate that both gold and silver appear promisingaslubricants for vacuum operation and that the bearings exhibit: (I) an early dip in speed or initial erratic performance, which indicates that a “run-in” period is required; (2) a sudden failure, rather than a gradual d&ease in speed, which makes the prediction of impending failure difficult. A stainless-steel (303) gear operating with a Deli-in gear at a pitch line velocity of 942 f.p.m. has operated for over 175 h, without failure, in a vacuum of IO-~ torr; and a stainless-steel gear operating with an aluminium gear of a pitch line velocity of f.p.m. has operated for over 700 h without failure, in a vacuum of 6’ ID-~ torr. A Magnetic Drive. O.A.Motovilovand S. N. Dekha, (1962) 6 pp; Sci. and Tech. Aevospace Repts., I (I) (1963) 46. N 63-~0330. Air Force Systems Command, Foreign Technology Div., Wright-Patterson AFB, Ohio, U.S.A. A magnetic drive, which produces rotational motion in a vacuum apparatus, is constructed so that the dimensions of the magnets are decreased without reducing the value of the torques transmitted by the magnets. This is accomplished by placing the magnets in a hermetically sealed box located outside the boundaries of the vacuum apparatus with the magnets separated by a thin nonmagnetic vacuum-tight membrane. The driven magnet is thus removed from the vacuum chamber proper. Thisensuresthepossibilityofestablish ing the necessary gap between the magnetic elements. which, in turn. allows their construction out of small, permanent magnets. Research on High-Temperature Bearings. R. D. Brown, R. A. Burton and P. M. Ku, (Wright-Patterson AFB, Ohio, Flight Dynamics lab.), (1962) 80 pp.; 15 refs. Sci. and Tech. Aemspacs Repts.. I (I) (1963) 46. N 63rorg4, Southwest Research Inst.. San Antonio, Tex. A description is presented of the evaluation work performed on oscillating bearings of both plain journal and self-aligning types. The bearing substrate materials included cermets LT-18 and LT-z, and alloys F-48 and Reng 41. Lubricants receiving extensive evaluation were a clad sitver-palladium ahoy, molybdenum disulfide used in cavities, and bonded molybdenum disulfide. Results include those from frictionandwearevaluations, radial load capacity tests on plain journal bearings, and axial and radial load capacity tests on self-aligning bearings. Vibration of Journal Beatlngs in Vacuum, K. E. Demorest and E. C. McKannan, Lubrication Eng., rg (2) (r963) 59-67; 8 fig.
251
Dry film lubricated bearing surfaces operating in a vacuum environment have been studied as a step in the analysis of the problem of lubrication in space. Journal bearings, which operated successfully at a pressure of one atmosphere, failed after a short time when exposed to a pressure on the order of 10-6 mm Hg. Failures were observed to be due to vibrations of the journal in the bushing rather than seizure or damaged surfaces. The vibrations observed in the vacuum environment apparently were damped in the atmospheric pressure tests. In this paper, the test svstem is described. and two *suggested approaches toward an explanation of the failures are discussed. The first approach, which was experimental, provided a direct measure of the radial motion of the journal along with the usual journal test data. The second approach, a mathematical analog, has been programmed on a computer and provided a plausible explanation of how a journal can vibrate to failure in a short time. The better understanding obtained of journal bearing failure causes has been helpful in the selection of improved hearing materials and in the designof bearing components for use in space. 4. a Bearings (See also sections 2.3, 2.4, 5.2 and 6) The Hydrodynamic Phenomena of Sliding Prlctfon in Cylindrical Bearings. (in Russian) I. M. Kolavev; Zap. Leningr. S.IKh. In-ta, (76) (1959) 81-87; Appl. Mech. Rev., 16 (I) (1963) 85, no. 637. The distribution of the pressure and the temperature in journal bearings 40 mm in diameter, with widths of 40 and 23 mm, at various specific loading up to 260 kg/cm8 and at 1420 revs/min of the journal (shaft] was experimentalty investigated. The proposal is made to utilize the pressure of the lubricating layer at a point corresponding to the direction of the load, to act as a parameter. With increase of the load on the bearing the pressure of the lubricant began to increase at first and then began to drop. Deformation then occurred and also the working-in of the anti-friction layer, which was expressed by the redistribution of the pressure in the layer of lubricant. With further increase in the load a regime commenced in which the pressure of the layer fell even in the seizing up of the bearing. The onset of a critical regime of this nature depends on the anti-friction metal in the bearing, the type of lubricant used, and other factors. Curves are furnished characterizing the critical regimes of work of a number of bearings. Dynamic Properties of Oil film in Slider Bearings, (in Russian) E. L. Poznyak, Izv. Akad. NazrkSSSR.Otd. Wear, 6 (1963) 243-255
250
ANT, CURRENT
including molybclmum disulphidc, is influenced be- the nature of the base lulrricant and the compstability of the additives. Water in oil has a detrimental effect which ran Ix counteracted by additivrs. lnvestigaadditives,
3. T.uRRrcnrroN A Model Experiment in Elasto-Hydrodynamic Lubrication. G, R. Higginson, Intwz. J. Mpch. Sci., 4 (1962) 205-2’0; A$$. Mpch. Rev., r6 (2) (1963) 173, no. 1310. Fuel and Lubricant Requirements of Modern High Output Two-stroke Cycle Outboard Motors. G. H. Millar and 13. Carlson, Lubrication Eng., 19 (1) (1963) 21~-27; 12 fig., I ref. Effect of Surface Coatings on the Load Carrying Capacity of Steel. G. F. Wolfe, Lubricalion Eng., ry (I) (1963) 28-35; 2 fig., 9 tables, 11 refs. The effect of various surface coatings on improving the load carrying and anti-wear characteristics of steel in silicone, dies&, and petroleum oils is presented. Data were obtained using the Falex machine, a roll tester, and a gear test stand. The surface coatings evaluated included metal plates, banded solid lubricants, flame sprayed coatings, salt bath treatments, and electric spark metal deposition. The resutts indicate that whenever the combination of steel sliding on steel is broken up, an improvement in load carrying capacity and anti-wear properties is obtained. Soft metal pIatcs and metals with low melting points improve the load carrying ability of steel in all oils. Silver plate is very effective. Diffusion processes which produce a definite case layer on steel also provide very satisfactoryseizureandanti-wearproperties. Several processes outperform conventional nitriding and carburizing. The most promising surface coatings should be considered for applications where increased load carrying ability or operation in unusual environments is required. Engineering applications of such coatings will. of course, depend on a full analysis of all the operating conditions as well as the particular characteristics of any specific surface.
EVENTS
tion by radio-active tracer technique has shotvn that accclcrated failure in the prescnct of water- may be due to hydrogen cmbrittll:ment.
AND LrrBRrcaNrs Physical and Chemical Properties of Complex Soap Greases. A. T. l’olishuk, Lz&icration fing., rp (2) (7963) 76.. 87; 16fig., 12 tables, 72 refs. The properties of soap particles and fibers characterize the structure and physical pmperties of their greases. But the chemistry of the soap molecule itself is the most significant factor. It is especially useful in defining complcx soap grcascs. It is suggested that cornl’lex soap greases be defined as those which are formed when two dissimilar acids arr attached to the same molecule. By this definition, only polyvalcnt elements can form true complex soaps. Complex soap greases arc among the best, currently available, multipurpose lubricants. The most commonly used complex greases arc those of calcium and barium soaps, yet they seem to offer little advantage over conventional lithium multipurpose greases. They have higher dropping points, and some calcium complexes offer built-in EP properties, but they have poor reversibility and dispensability characteristics. Barium complexes require high soap contents and are costly. Aluminum complex greases arc the best of the complex greases. They have excellent pumpabilitv characteristics, good mechanical and oxidation stability, and outstanding rcsistance to oil separation when subjcctcd to pressure and/or tcmpcraturc. Wear and Corrosion Tendencies of Molybdenum Disulfide~Contaiuing Greases. S. F. Calhoun, Tech. Rept., (1962) 13 pp., 19 refs., Sci. and Tech. .4crospace Repts., 1 (2) (1963) III. The tendency of molybdenum disulfide to increase the wear of greases is shown by results of laboratory tests. The extreme pressure properties of greases were increased by the addition of the molybdenum disulfide. It also promotes rusting of ferrous metals when added to grease.
4. MACHINE PARTS 4.x Mechanical
ditions
Elements
under Entveme
Con-
MechanicalElementsforVacuumOperation. H. E. Evans, T. W. Flately and M. Francis Federline, Sci. and Tech. Aerospace Rep&., I (3) (1963) 182. N 63-11278, NASA;Presented at the ARS 17th Ann. Meeting and Space
Flight Exposition, Los Angeles, Nov. 13-18, 1962 ; (ARS Paper 2711-62) 12 pp. The first two phases of a program investigating the high-speed operation of miniature ball bearings with metallic film lubrication and the first phase of an investigation for determining the “best bet” gear material combinations
SYSTEMATIC ABSTRACTS and methods of lubrication are included. Results of the bearing study indicate that both gold and silver appear promisingaslubricants for vacuum operation and that the bearings exhibit: (I) an early dip in speed or initial erratic performance, which indicates that a “run-in” period is required; (2) a sudden failure, rather than a gradual d&ease in speed, which makes the prediction of impending failure difficult. A stainless-steel (303) gear operating with a Deli-in gear at a pitch line velocity of 942 f.p.m. has operated for over 175 h, without failure, in a vacuum of IO-~ torr; and a stainless-steel gear operating with an aluminium gear of a pitch line velocity of f.p.m. has operated for over 700 h without failure, in a vacuum of 6’ ID-~ torr. A Magnetic Drive. O.A.Motovilovand S. N. Dekha, (1962) 6 pp; Sci. and Tech. Aevospace Repts., I (I) (1963) 46. N 63-~0330. Air Force Systems Command, Foreign Technology Div., Wright-Patterson AFB, Ohio, U.S.A. A magnetic drive, which produces rotational motion in a vacuum apparatus, is constructed so that the dimensions of the magnets are decreased without reducing the value of the torques transmitted by the magnets. This is accomplished by placing the magnets in a hermetically sealed box located outside the boundaries of the vacuum apparatus with the magnets separated by a thin nonmagnetic vacuum-tight membrane. The driven magnet is thus removed from the vacuum chamber proper. Thisensuresthepossibilityofestablish ing the necessary gap between the magnetic elements. which, in turn. allows their construction out of small, permanent magnets. Research on High-Temperature Bearings. R. D. Brown, R. A. Burton and P. M. Ku, (Wright-Patterson AFB, Ohio, Flight Dynamics lab.), (1962) 80 pp.; 15 refs. Sci. and Tech. Aemspacs Repts.. I (I) (1963) 46. N 63rorg4, Southwest Research Inst.. San Antonio, Tex. A description is presented of the evaluation work performed on oscillating bearings of both plain journal and self-aligning types. The bearing substrate materials included cermets LT-18 and LT-z, and alloys F-48 and Reng 41. Lubricants receiving extensive evaluation were a clad sitver-palladium ahoy, molybdenum disulfide used in cavities, and bonded molybdenum disulfide. Results include those from frictionandwearevaluations, radial load capacity tests on plain journal bearings, and axial and radial load capacity tests on self-aligning bearings. Vibration of Journal Beatlngs in Vacuum, K. E. Demorest and E. C. McKannan, Lubrication Eng., rg (2) (r963) 59-67; 8 fig.
251
Dry film lubricated bearing surfaces operating in a vacuum environment have been studied as a step in the analysis of the problem of lubrication in space. Journal bearings, which operated successfully at a pressure of one atmosphere, failed after a short time when exposed to a pressure on the order of 10-6 mm Hg. Failures were observed to be due to vibrations of the journal in the bushing rather than seizure or damaged surfaces. The vibrations observed in the vacuum environment apparently were damped in the atmospheric pressure tests. In this paper, the test svstem is described. and two *suggested approaches toward an explanation of the failures are discussed. The first approach, which was experimental, provided a direct measure of the radial motion of the journal along with the usual journal test data. The second approach, a mathematical analog, has been programmed on a computer and provided a plausible explanation of how a journal can vibrate to failure in a short time. The better understanding obtained of journal bearing failure causes has been helpful in the selection of improved hearing materials and in the designof bearing components for use in space. 4. a Bearings (See also sections 2.3, 2.4, 5.2 and 6) The Hydrodynamic Phenomena of Sliding Prlctfon in Cylindrical Bearings. (in Russian) I. M. Kolavev; Zap. Leningr. S.IKh. In-ta, (76) (1959) 81-87; Appl. Mech. Rev., 16 (I) (1963) 85, no. 637. The distribution of the pressure and the temperature in journal bearings 40 mm in diameter, with widths of 40 and 23 mm, at various specific loading up to 260 kg/cm8 and at 1420 revs/min of the journal (shaft] was experimentalty investigated. The proposal is made to utilize the pressure of the lubricating layer at a point corresponding to the direction of the load, to act as a parameter. With increase of the load on the bearing the pressure of the lubricant began to increase at first and then began to drop. Deformation then occurred and also the working-in of the anti-friction layer, which was expressed by the redistribution of the pressure in the layer of lubricant. With further increase in the load a regime commenced in which the pressure of the layer fell even in the seizing up of the bearing. The onset of a critical regime of this nature depends on the anti-friction metal in the bearing, the type of lubricant used, and other factors. Curves are furnished characterizing the critical regimes of work of a number of bearings. Dynamic Properties of Oil film in Slider Bearings, (in Russian) E. L. Poznyak, Izv. Akad. NazrkSSSR.Otd. Wear, 6 (1963) 243-255