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  • 1
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    Comparison of conventional and microasperity elastohydrodynamic lubrication of a ballspinning in a nonconforming groove (1972)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An analysis was developed for the microasperity elastohydrodynamic lubrication of a ball spinning in a nonconforming groove. This analysis was compared to the conventional elastohydrodynamic analysis of a ball spinning in a nonconforming groove. Rheological models for a di-2-ethylhexyl sebacate, a super-refined naphthenic mineral oil, and a polyphenyl ether (5P4E) were constructed from spinning torque data by using both analyses. The value of the lubricant pressure-viscosity coefficient that makes the data fit the analyses of the fluids differs somewhat from published data. For all three lubricants, an exponential composite model best described the lubricant rheology. Good agreement existed with the experimental and analytical values of torque for both the conventional and microasperity elastohydrodynamic analysis for a spinning ball in a nonconforming groove.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-TN-D-6761 , E-6713
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Pitting fatigue characteristics of AISI M-50 and super nitralloy spur gears (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Two groups of 3.50-in. pitch-diameter spur gears, without tip relief, made from consumable-electrode vacuum-melted (CVM) AISI M-50 steel and CVM super nitralloy (5Ni-2A1) were tested under conditions which produced fatigue pitting. The M-50 gears had fatigue lives approximately 50 percent longer than the super nitralloy gears. Both groups of gears failed by classical rolling-element fatigue at the pitch circle. When the gears were overrun past initial spall formation, the spalled M-50 gear teeth failed by fatigue fracture. The M-50 material had higher wear than the super nitralloy material. Differences in fatigue life and wear were not considered statistically significant.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-TN-D-7261 , E-7164
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Lubricant selection for gear designers (1972)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Guide for gear designers, consisting of theory, calculations, charts, curves and references, explains lubrication requirements for gears to insure maximum performance. Mechanical and service variables are considered in order to obtain optimum gear performance under severe operating conditions.
    Keywords: MATERIALS
    Type: LEW-11483
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Lubrication considerations in gear design (1970)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Lubrication considerations in design of gears
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-TM-X-52942
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    Effects of antiwear and extreme pressure additives in a synthetic paraffinic lubricant on ball spinning torque (1970)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Effects of antiwear and extreme-pressure additives in synthetic paraffinic oil on ball spinning torque
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-TN-D-5820
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Study of lubricant jet flow phenomena in spur gears (1974)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Review of the results of lubrication tests conducted in the NASA-Lewis Research Center gear test apparatus modified for high speed photography of gear tooth lubrication. The experimental results are compared with an analytical model that includes windage effects. The resulting findings show that the analytical model provides good agreement with the experimental impingement depth and that small oil drops are affected by gear windage. For this reason, the best lubrication is provided when the oil jet is not atomized.
    Keywords: MECHANICAL ENGINEERING
    Type: ASME PAPER 74-LUB-3 , American Society of Mechanical Engineers and American Society of Lubrication Engineers, Joint Lubrication Conference; Oct 08, 1974 - Oct 10, 1974; Montreal; Canada
    Format: text
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  • 7
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    Study of lubricant jet flow phenomena in spur gears (1974)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Lubricant jet flow impingement and penetration depth into a gear tooth space were measured at 4920 and 2560 rpm using a 8.89 cm (3.5 inch) pitch diameter 8 pitch spur gear at oil pressures from 70,000 to 410,000 n/sqm (10 psi to 60 psi). A high speed motion picture camera was used with xenon and high speed stroboscopic lights to slow down and stop the motion of the oil jet. An analytical model was developed for the vectorial impingement dept and for the impingement depth with tooth space windage effects included. The windage effects for oil drop size greater than .0076 cm (.003 inches). The analytical impingement dept compared favorably with experimental results above an oil jet pressure of 70,000 n/sqm (10psi). There was further penetration into the tooth space after impingement, but much of this oil was thrown out of the tooth space without further contacting the gear teeth.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-TM-X-71572 , E-8012 , lubrication Conf.; Oct 08, 1974 - Oct 10, 1974; Montreal
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Elastohydrodynamic principles applied to the design of helicopter components. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Elastohydrodynamic principles affecting the lubrication of transmission components are presented and discussed. Surface temperatures of the transmission bearings and gears affect elastohydrodynamic film thickness. Traction forces and sliding as well as the inlet temperature determine surface temperatures. High contact ratio gears cause increased sliding and may run at higher surface temperatures. Component life is a function of the ratio of elastohydrodynamic film thickness to composite surface roughness. Lubricant starvation reduces elastohydrodynamic film thickness and increases surface temperatures. Methods are presented which allow for the application of elastohydrodynamic principles to transmission design in order to increase system life and reliability.
    Keywords: STRUCTURAL MECHANICS
    Type: AHS PREPRINT 770 , Annual National Forum; May 09, 1973 - May 11, 1973; Washington, DC
    Format: text
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    NASA TECHNICAL REPORTS
  • 9
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    A life study of AISI M-50 and Super Nitralloy spur gears with and without tip relief (1973)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Tests were conducted at 170 F with groups of 3.5-in.-pitch-diameter spur gear with and without tip relief made of consumable-electrode vacuum melted (CVM) Spur Nitralloy (5Ni-2Al) and CVM AISI M-50 steel. The AISI M-50 gears without tip relief had lives approximately 50 percent longer than the Super Nitralloy gears without tip relief. However, the Super Nitralloy gears with tip relief had lives equal to the AISI M-50 gears without tip relief. The difference in lives were not statistically significant. All gears failed by classical pitting fatigue at the pitch circle. However, the AIAI M-50 gears with tip relief failed by tooth fracture. AISI M-50 gear sets without tip relief having a spalled gear tooth which were deliberately overrun after spalling had occurred, failed by tooth fracture.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-TM-X-68269 , E-7575 , Joint Lubrication Conf.; Oct 16, 1973 - Oct 18, 1973; Atlanta, GA; United States
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    NASA TECHNICAL REPORTS
  • 10
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    Elastohydrodynamic principles applied to the design of helicopter components (1973)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Elastohydrodynamic principles affecting the lubrication of transmission components are presented and discussed. Surface temperature of the transmission bearings and gears affect elastohydrodynamic film thickness. Traction forces and sliding as well as the inlet temperature determine surface temperatures. High contact ratio gears cause increased sliding and may run at higher surface temperatures. Component life is a function of the ratio of elastohydrodynamic film thickness to composite surface roughness. Lubricant starvation reduces elastrohydrodynamic film thickness and increases surface temperatures. Methods are presented which allow for the application of elastohydrodynamic principles to transmission design in order to increase system life and reliability.
    Keywords: AIRCRAFT
    Type: NASA-TM-X-68215 , Natl. Forum of the Am. Helicopter Soc.; May 10, 1973 - May 11, 1973; Washington, D. C.; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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