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  • 11
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    Effect of tip relief on endurance characteristics of super nitralloy and AISI M-50 spur gears (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Tests were conducted with two groups of 8.89-centimeter (3.5-in.) pitch diameter spur gears with standard 20 deg involute profile with tip relief made of CVM Super-Nitralloy (5Ni-2Al) and CVM AISI M-50 at a temperature of 350 K (170 F). Super-Nitralloy gears with tip relief had a life 150 percent that of gears without tip relief. An increased scoring phenomenon was noted with the Super-Nitralloy gears with tip relief. Through-hardened AISI M-50 gears with tip relief failed due to tooth fracture. AISI M-50 gears without tip relief had a life approximately 40 times greater than the AISI M-50 gears with tip relief.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-TN-D-7535
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 12
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    Friction losses in a lubricated thrust-loaded cageless angular-contract bearing (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The NASA spinning torque apparatus was modified to measure the spinning torque on a cageless ball thrust bearing. Friction torque was measured for thrust loads varying from 44.5 to 403 newtons (10 to 90 lb) at speeds of 1000, 2000, and 3000 rpm. Tests were conducted with di-2-ethylhexyl sebacate and a synthetic paraffinic oil. These tests were run with either oil jet lubrication or with a thin surface film of lubricant only. An analytical model which included rolling resistance was developed and extended from previous models for spinning torque and lubricant rheology. The model was extended by the inclusion of rolling resistance. The computed values were in fair agreement with the experimental results and confirmed previous hypotheses that a thin lubricant film gives minimum bearing torque and an oil jet flow of a viscous lubricant will result in considerable rolling torque in addition to the torque due to ball spin.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-TN-D-7356 , E-7284
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 13
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    New generalized rheological model for lubrication of a ball spinning in a nonconforming groove (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The elastohydrodynamic theory for predicting the spinning friction of a ball in a nonconforming groove was modified to incorporate a rheological model. The rheological model is based on the exponential pressure viscosity relation for low shear stresses, but at high shear rates and pressures, the relation is altered to one in which the shear stress is porportional to the normal stress. The model was fitted to experimental spinning torques for four different lubricants: a synthetic paraffinic lubricant, di-2-ethylhexyl sebacate, a super-refined naphthenic mineral oil, and a polyphenyl ether (5P4E). Good agreement between the model and experiment was found.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-TN-D-7280 , E-7256
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 14
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    Rolling-element lubrication with fluorinated polyether at cryogenic temperatures /160 deg to 410 deg R/ (1969)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Rolling element lubrication tests using fluorinated polyether fluids at cryogenic temperatures
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-TN-D-5566
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 15
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    A life study of AISI M-50 and Super Nitralloy spur gears with and without tip relief (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: ASME PAPER 73-LUB-38 , Joint Lubrication Conference; Oct 15, 1973 - Oct 18, 1973; Atlanta, GA; US
    Format: text
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    NASA TECHNICAL REPORTS
  • 16
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    The application of elastohydrodynamic lubrication in gear tooth contacts. (1972)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: It is shown that in the early stages of design, scoring and fatigue failure of gear contact surfaces can be prevented by the following means: improving load capacity with the aid of tip relief, or by improved surface finish; by giving special care to the location and application of the lubricant in high-speed or high-load gear applications; by determining the thickness of the elastohydrodynamic film from an analysis for the worst temperature, speed, and load conditions, and selecting the appropriate lubricant from this analysis; by using an additive in the case of frequent repeated startup and shutdown conditions; by taking the expected temperature, speed, and load in the selection of an extreme pressure additive; and by systematically testing any new transmission or gear box design.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: International Lubrication Conference; Oct 09, 1972 - Oct 12, 1972; New York, NY; US
    Format: text
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    NASA TECHNICAL REPORTS
  • 17
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    Study of ball bearing torque under elastohydrodynamic lubrication (1973)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Spinning and rolling torques were measured in an angular-contact ball bearing with and without a cage under several lubrication regimes in a modified NASA spinning torque apparatus. Two lubricants were used, a di-2 ethylhexyl sebacate and a synthetic paraffinic oil, at shaft speeds of 1000, 2000, and 3000 rpm and bearing loads from 10 lbs to 90 lbs. An analytical model was developed from previous spinning friction models to include rolling with spinning under lubrication regimes from thin film to flooded conditions. The bearing torque values have a wide variation, under any condition of speed and load, depending on the amount of lubricant present in the bearing. The analytical model compared favorably with experimental results under several lubrication regimes.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-TM-X-68271 , E-7284 , Joint Lubrication Conf.; Oct 16, 1973 - Oct 18, 1973; Atlanta, GA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 18
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    The application of elastohydrodynamic lubrication in gear tooth contacts (1972)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An analytical method is presented for determining elastohydrodynamic film thickness in gears from theory and how the film affects gear failure and life. The practical aspects of gear lubrication are presented, including mechanical and service variables which must be considered to obtain optimum gear performance under severe operating conditions.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-TM-X-68142 , E-7146 , Intern. Lubrication Conf.; Oct 09, 1972 - Oct 13, 1972; New York
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 19
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    Elastohydrodynamic lubrication of a spinning ball in a nonconforming groove. (1969)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Elastohydrodynamic solution for ball torque spinning without rolling in nonconforming groove, showing increase in torque with stress and spinning and decreasing conformity
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: ASME PAPER 69-LUBS-11 , AMERICAN SOCIETY OF MECHANICAL ENGINEERS, LUBRICATION SYMPOSIUM; Jun 17, 1969 - Jun 19, 1969; SAN FRANCISCO, CALIF.
    Format: text
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    NASA TECHNICAL REPORTS
  • 20
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    Lubricants for inerted lubrication systems in engines for advanced aircraft (1968)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Lubricants for recirculating inerted lubrication systems in Mach 3 aircraft engines
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-TM-X-52418 , NATL. AIR TRANSPORTATION MEETING; Apr 29, 1968 - May 02, 1968; NEW YORK
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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