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  • 1
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    Effects of gear box vibration and mass imbalance on the dynamics of multistage gear transmission (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The dynamic behavior of multistage gear transmission system, with the effects of gear-box-induced vibrations and rotor mass-imbalances is analyzed. The model method, using undamped frequencies and planar mode shapes, is used to reduce the degree-of-freedom of the system. The various rotor-bearing stages as well as lateral and torsional vibrations of each individual stage are coupled through localized gear-mesh-tooth interactions. Gear-box vibrations are coupled to the gear stage dynamics through bearing support forces. Transient and steady state dynamics of lateral and torsional vibrations of the geared system are examined in both time and frequency domain. A typical three-staged geared system is used as an example. Effects of mass-imbalance and gear box vibrations on the system dynamic behavior are presented in terms of modal excitation functions for both lateral and torsional vibrations. Operational characteristics and conclusions are drawn from the results presented.
    Keywords: MECHANICAL ENGINEERING
    Type: ASME, Transactions, Journal of Vibration and Acoustics (ISSN 0739-3717); 113; 333-344
    Format: text
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  • 2
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    Into mesh lubrication of spur gears with arbitrary offset oil jet. I - For jet velocity less than or equal to gear velocity (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: An analysis was conducted for into mesh oil jet lubrication with an arbitrary offset and inclination angle from the pitch point for the case where the oil jet velocity is equal to or less than pitch line velocity. The analysis includes the case for the oil jet offset from the pitch point in the direction of the pinion and where the oil jet is inclined to intersect the common pitch point. Equations were developed for the minimum oil jet velocity required to impinge on the pinion or gear and the optimum oil jet velocity to obtain the maximum impingement depth.
    Keywords: MECHANICAL ENGINEERING
    Type: ASME; 713-718
    Format: text
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  • 3
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    NASA transmission research and its probable effects on helicopter transmission design (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Transmissions studied for application to helicopters in addition to the more conventional geared transmissions include hybrid (traction/gear), bearingless planetary, and split torque transmissions. Research is being performed to establish the validity of analysis and computer codes developed to predict the performance, efficiency, life, and reliability of these transmissions. Results of this research should provide the transmission designer with analytical tools to design for minimum weight and noise with maximum life and efficiency. In addition, the advantages and limitations of drive systems as well as the more conventional systems will be defined.
    Keywords: MECHANICAL ENGINEERING
    Format: text
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  • 4
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    Status of Understanding for Gear Materials (1984)
    In:  CASI
    Details
    Publication Date: 2014-09-11
    Description: A wide variety of gear materials is available today for the gear designer. The choice of which material to use should be based on the requirements of the application and will include the operating conditions of load, speed, and temperature in addition to reliability, weight, noise limitation, accuracy, and cost. In aircraft applications such as helicopters, V/STOL aircraft, and turboprops, the dominant factors to be considered are reliability and weight. The following gear materials are reviewed herein with an emphasis upon mechanical properties, cost, and durability: plastics, nonferrous metals, copper alloys, iron alloys, metal powders, and steels.
    Keywords: MECHANICAL ENGINEERING
    Type: Tribology in the 80's, vol. 2; p 795-809
    Format: text
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  • 5
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    Determination of Principal Curvatures and Contact Ellipse for Profile Crowned Helical Gears (1999)
    In:  Other Sources
    Details
    Publication Date: 2011-08-23
    Description: Helical gears with localized bearing contact of tooth surfaces achieved by profile crowning of tooth surfaces are considered. Profile crowning is provided by application of two imaginary rack-cutters with mismatched surfaces. The goal is to determine the dimensions and orientation of the instantaneous contact ellipse that requires the determination of principle curvatures of pinion-gear tooth surfaces. A simplified solution to this problem is proposed based on the approach development for correlation of principal curvatures and directions of generating and generated tooth surfaces. The obtained equations are applied for profile crowning where the normal profiles of the rack-cutters are either a circular arc or a straight line.
    Keywords: Mechanical Engineering
    Type: Journal of Mechanical Design; Volume 121; 107-111
    Format: text
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  • 6
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    Computerized Simulation of Meshing of Conventional Helical Involute Gears and Modification of Geometry (1997)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An approach is proposed for computerized simulation of meshing of aligned and misaligned involute helical gears. Algorithms for TCA (Tooth Contact Analysis) computer programs were developed. Influence of misalignment on the shift of the bearing contact and transmission errors has been investigated. Numerical examples that illustrate the developed theory are provided.
    Keywords: Mechanical Engineering
    Type: NASA-TM-107451 , E-10732 , NAS 1.15:107451 , ARL-TR-1370
    Format: application/pdf
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  • 7
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    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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  • 8
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    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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  • 9
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    Gear Lubrication and Cooling Experiment and Analysis (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A gear tooth temperature analysis was performed using a finite element method combined with a calculated heat input, a calculated oil jet impingement depth, and estimated heat transfer coefficients for the different parts of the gear tooth that are oil cooled and air cooled. Experimental measurements of gear tooth average surface temperature and gear tooth instantaneous surface temperature were made with a fast response, infrared, radiometric microscope. Increasing oil pressure has a significant effect on both average surface temperature and peak surface temperature at loads above 1895 N/cm(1083 lb/in) and speeds of 10,000 and 7500 rpm. Both increasing speed (from 5000 to 10,000 rpm) at constant speed cause a significant rise in the average surface temperature and in the instantaneous peak surface temperatures on the gear teeth. The oil jet pressure required to provide the best cooling for gears is the pressure required to obtain full gear tooth impingement. Calculated results for gear tooth temperatures were close to experimental results for various oil jet impingement depths for identical operating conditions.
    Keywords: MECHANICAL ENGINEERING
    Type: Advanced Power Transmission Technol.; p 477-490
    Format: application/pdf
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  • 10
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    An update on the life analysis of spur gears (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An analytical method for predicting surface fatigue life of gears was presented. General statistical methods were outlined, showing the application of the general methods to a simple gear mesh. Experimentally determined values for constants in the life equation were given. Comparison of the life theory with test results and AGMA standards was made. Gear geometry pertinent to life calculations was reviewed.
    Keywords: MECHANICAL ENGINEERING
    Type: Advanced Power Transmission Technol.; p 421-434
    Format: application/pdf
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