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  • 1985-1989  (20)
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  • 1
    facet.materialart.
    Unknown
    An investigation of the transient thermal analysis of spur gears (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A finite element computer program is developed for evaluating the transient behavior of surface temperature in high performance spur gears. The time dimension is implemented using two and three point finite difference schemes. The different schemes are provided for the purpose of numerical stability and convergence studies. A detailed explanation of the gear cooling process leading to the establishment of a modified Blok model is also included. Other conventional models for approximating the heat transfer coefficients are available for comparison. Preliminary results are given showing snap shots of gear temperature contours at the initial stages of tooth engagement.
    Keywords: MECHANICAL ENGINEERING
    Type: ASME PAPER 84-DET-92 , ASME; 541-548
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    Gearing (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Gearing technology in its modern form has a history of only 100 years. However, the earliest form of gearing can probably be traced back to fourth century B.C. Greece. Current gear practice and recent advances in the technology are drawn together. The history of gearing is reviewed briefly in the Introduction. Subsequent sections describe types of gearing and their geometry, processing, and manufacture. Both conventional and more recent methods of determining gear stress and deflections are considered. The subjects of life prediction and lubrication are additions to the literature. New and more complete methods of power loss predictions as well as an optimum design of spur gear meshes are described. Conventional and new types of power transmission systems are presented.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-RP-1152 , E-2003 , NAS 1.61:1152 , AVSCOM-TR-84-C-15
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    Effect of five lubricants on life of AISI 9310 spur gears (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Spur-gear surface fatigue tests were conducted with five lubricants using a single lot of consumable-electrode vacuum melted (CVM) AISI 9310 spur gears. The lot of gears was divided into five groups, each of which was tested with a different lubricant. The test lubricants are classified as either a synthetic hydrocarbon, mineral oil, or ester-based lubricant. All five lubricants have imilar viscosity and pressure-viscosity coefficients. A pentaerythritol base stock without sufficient antiwear additives produced a surface fatigue life pproximately 22 percent that of the same base stock with chlorine and phosphorus type additives. The presence of sulfur type antiwear additives in the lubricant did not appear to affect the surface fatigue life of the gears tested. No statistical difference in the 10-percent surface fatigue life was produced with four of the five lubricants.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-TP-2419 , E-2183 , NAS 1.60:2419
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    Lubricant jet flow phenomena in spur and helical gears with modified center distances and/or addendums - For out-of-mesh conditions (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Out-of-mesh jet lubrication of gears was examined. The pinion impingement cycle was described briefly. An analysis was developed for the lubricant jet flow in the out-of-mesh condition. The analysis provides for the inclusion of modified center distances and modified addendum. Equations were generated for the limit values of variables necessary to remove the severe limitations to facilitate computer analysis. A computer program was designed using these limit formulas to prevent negative impingement (missing) on the pinion.
    Keywords: MECHANICAL ENGINEERING
    Type: ASME PAPER 84-DET-96 , ASME; 24-30
    Format: text
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  • 5
    facet.materialart.
    Unknown
    Lubrication and cooling for high speed gears (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The problems and failures occurring with the operation of high speed gears are discussed. The gearing losses associated with high speed gearing such as tooth mesh friction, bearing friction, churning, and windage are discussed with various ways shown to help reduce these losses and thereby improve efficiency. Several different methods of oil jet lubrication for high speed gearing are given such as into mesh, out of mesh, and radial jet lubrication. The experiments and analytical results for the various methods of oil jet lubrication are shown with the strengths and weaknesses of each method discussed. The analytical and experimental results of gear lubrication and cooling at various test conditions are presented. These results show the very definite need of improved methods of gear cooling at high speed and high load conditions.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-87096 , E-2660 , NAS 1.15:87096
    Format: application/pdf
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  • 6
    facet.materialart.
    Unknown
    Surface fatigue life and failure characteristics of EX-53, CBS 1000M, and AISI 9310 gear materials (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Spur gear endurance tests and rolling-element surface fatigue tests are conducted to investigate EX-53 and CBS 1000M steels for use as advanced application gear materials, to determine their endurance characteristics, and to compare the results with the standard AISI 9310 gear material. The gear pitch diameter is 8.89 cm (3.50 in). Gear test conditions are an oil inlet temperature of 320 K (116 F), an oil outlet temperature of 350 K (170 F), a maximum Hertz stress of 1.71 GPa (248 ksi), and a speed of 10,000 rpm. Bench-type rolling-element fatigue tests are conducted at ambient temperature with a bar specimen speed of 12,500 rpm and a maximum Hertz stress of 4.83 GPa (700 ksi). The EX-53 test gears have a surface fatigue life of twice that of the AISI 9310 spur gears. The CBS 1000M test gears have a surface fatigue life of more than twice that of the AISI 9310 spur gears. However, the CBS 1000M gears experience a 30-percent tooth fracture failure which limits its use as a gear material. The rolling-contact fatigue lines of RC bar specimens of EX-53 and ASISI 9310 are approximately equal. However, the CBS 1000M RC specimens have a surface fatigue life of about 50 percent that of the AISI 9310.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TP-2513 , E-2578 , NAS 1.60:2513
    Format: application/pdf
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  • 7
    facet.materialart.
    Unknown
    Profile modification to minimize spur gear dynamic loading (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An analytical computer simulation program for dynamic modeling of low-contact-ratio spur gear systems is presented. The procedure computes the static transmission error of the gears operating under load and uses a fast Fourier transform to generate the frequency spectrum of the static transmission error at various tooth profile modifications. The dynamic loading response of an unmodified (perfect involute) gear pair was compared with that of gears with various profile modifications. Correlations were found between various profile modifications and the resulting dynamic loads. An effective error, obtained from frequency domain analysis of the static transmission error of the gears, gave a very good indication of the optimum profile modification to reduce gear dynamic loading. Design curves generated by dynamic simulation at various profile modifications are given for gear systems operated at various loads. Optimum profile modifications can be determined from these design curves for improved gear design.
    Keywords: MECHANICAL ENGINEERING
    Type: 1989 International Power Transmission and Gearing Conference; Apr 25, 1989 - Apr 28, 1989; Chicago, IL; United States
    Format: text
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  • 8
    facet.materialart.
    Unknown
    Vibration signature analysis of multistage gear transmission (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An analysis is presented for multistage multimesh gear transmission systems. The analysis predicts the overall system dynamics and the transmissibility to the gear box or the enclosed structure. The modal synthesis approach of the analysis treats the uncoupled lateral/torsional model characteristics of each stage or component independently. The vibration signature analysis evaluates the global dynamics coupling in the system. The method synthesizes the interaction of each modal component or stage with the nonlinear gear mesh dynamics and the modal support geometry characteristics. The analysis simulates transient and steady state vibration events to determine the resulting torque variations, speeds, changes, rotor imbalances, and support gear box motion excitations. A vibration signature analysis examines the overall dynamic characteristics of the system, and the individual model component responses. The gear box vibration analysis also examines the spectral characteristics of the support system.
    Keywords: MECHANICAL ENGINEERING
    Type: 1989 International Power Transmission and Gearing Conference; Apr 25, 1989 - Apr 28, 1989; Chicago, IL; United States
    Format: text
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    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unknown
    The role of thermal and lubricant boundary layers in the transient thermal analysis of spur gears (1989)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An improved convection heat-transfer model has been developed for the prediction of the transient tooth surface temperature of spur gears. The dissipative quality of the lubricating fluid is shown to be limited to the capacity extent of the thermal boundary layer. This phenomenon can be of significance in the determination of the thermal limit of gears accelerating to the point where gear scoring occurs. Steady-state temperature prediction is improved considerably through the use of a variable integration time step that substantially reduces computer time. Computer-generated plots of temperature contours enable the user to animate the propagation of the thermal wave as the gears come into and out of contact, thus contributing to better understanding of this complex problem. This model has a much better capability at predicting gear-tooth temperatures than previous models.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-101435 , E-4413 , NAS 1.15:101435 , AVSCOM-TR-88-C-032 , AD-A205574 , International Power Transmission and Gearing Conference; Apr 25, 1989 - Apr 27, 1989; Chicago, IL; United States
    Format: application/pdf
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  • 10
    facet.materialart.
    Unknown
    Vibration signature analysis of multistage gear transmission (1989)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An analysis is presented for multistage multimesh gear transmission systems. The analysis predicts the overall system dynamics and the transmissibility to the gear box or the enclosed structure. The modal synthesis approach of the analysis treats the uncoupled lateral/torsional model characteristics of each stage or component independently. The vibration signature analysis evaluates the global dynamics coupling in the system. The method synthesizes the interaction of each modal component or stage with the nonlinear gear mesh dynamics and the modal support geometry characteristics. The analysis simulates transient and steady state vibration events to determine the resulting torque variations, speeds, changes, rotor imbalances, and support gear box motion excitations. A vibration signature analysis examines the overall dynamic characteristics of the system, and the individual model component responses. The gear box vibration analysis also examines the spectral characteristics of the support system.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-101442 , E-4534 , NAS 1.15:101442 , AVSCOM-TR-88-C-040 , AD-A233516 , International Power Transmission and Gearing Conference; Apr 25, 1989 - Apr 27, 1989; Chicago, IL; United States
    Format: application/pdf
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