WorldCat Identities

Coy, John J.

Overview
Works: 45 works in 88 publications in 1 language and 1,899 library holdings
Roles: Author
Classifications: TL521.3, 621.833
Publication Timeline
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Most widely held works by John J Coy
Correlation of asperity contact-time fraction with elastohydrodynamic film thickness in a 20-millimeter-bore ball bearing by John J Coy( Book )

5 editions published in 1979 in English and held by 97 WorldCat member libraries worldwide

Vibration characteristics of OH-58A helicopter main rotor transmission by David G Lewicki( Book )

7 editions published in 1987 in English and held by 91 WorldCat member libraries worldwide

Experimental vibration tests covering a range of torque and speed conditions were performed on the OH-58A helicopter main rotor transmission at the NASA Lewis Research Center. Signals from accelerometers located on the transmission housing were analyzed by using Fourier spectra, power spectra, power spectral density functions, and averaging techniques. Most peaks of the Fourier spectra occurred at the spiral bevel and planetary gear mesh harmonics. The highest level of vibration occurred at the spiral bevel and planetary gear mesh harmonics. The highest level of vibration occurred at the spiral bevel meshing frequency. Transmission speed and vibration measurement location had a significant effect on measured vibration; transmission torque and measurement direction had a small effect
Advanced transmission studies by John J Coy( Book )

4 editions published in 1988 in English and held by 87 WorldCat member libraries worldwide

The NASA Lewis Research Center and the U.S. Army Aviation Systems Command share an interest in advancing the technology for helicopter propulsion systems. In particular, this paper presents highlights from that portion of the program in drive train technology and the related mechanical components. The major goals of the program are to increase life, reliability, and maintainability; reduce the weight, noise, and vibration; and maintain the relatively high mechanical efficiency of the gear train. The current activity emphasizes noise reduction technology and analytical code development followed by experimental verification. Selected significant advances in technology for transmissions are reviewed, including advanced configurations and new analytical tools. Finally, the plan for transmission research in the future is presented
Helicopter transmission research at NASA Lewis Research Center by Dennis P Townsend( Book )

2 editions published in 1988 in English and held by 86 WorldCat member libraries worldwide

A joint helicopter transmission research program between NASA Lewis Research Center and the U.S. Army Aviation Systems command has existed since 1970. Program goals are to reduce weight and noise and to increase life and reliability. This paper reviews significant advances i technology for gears and transmissions and describes the experimental facilities at NASA Lewis for helicopter transmission testing. A description of each of the rigs is presented along with some significant results from the experiments
Identification and proposed control of helicopter transmission noise at the source( Book )

2 editions published in 1987 in English and held by 84 WorldCat member libraries worldwide

Helicopter cabin interiors require noise treatment which is expensive and adds weight. The gears inside the main power transmission are major sources of cabin noise. This paper describes work conducted by the NASA Lewis Research Center in measuring cabin interior noise and in relating the noise spectrum to the gear vibration of the Army's OH-58 helicopter. Flight test data indicate that the planetary gear train is a major source of cabin noise and that other low frequency sources are present that could dominate the cabin noise. Companion vibration measurements were made in a transmission test stand, revealing that the single largest contributor to the transmission vibration was the spiral bevel gear mesh. Our current understanding of the nature and causes of gear and transmission noise is discussed. The authors believe that the kinematical errors of the gear mesh have a strong influence on the noise. This paper summarizes completed NASA/Army sponsored research that applies to transmission noise reduction. The continuing research program is also reviewed
Helicopter transmission testing at NASA Lewis Research Center by David G Lewicki( Book )

1 edition published in 1987 in English and held by 84 WorldCat member libraries worldwide

Minimization of the vibration energy of thin-plate structure by Katsumi Inoue( Book )

2 editions published in 1992 in English and held by 84 WorldCat member libraries worldwide

An optimization method is proposed to reduce the vibration of thin-plate structures. The method is based on a finite-element shell analysis, a modal analysis, and a structural optimization method. In the finite-element analysis, a triangular shell element with 18 degrees of freedom is used. In the optimization, the overall vibration energy of the structure is adopted as the objective function, and it is minimized at the given exciting frequency by varying the thickness of the elements. The technique of modal analysis is used to derive the sensitivity of the vibration energy with respect to the design variables. The sensitivity is represented by the sensitivities of both eigenvalues and eigenvectors. The optimum value is computed by the gradient projection method and a unidimensional search procedure under the constraint condition of constant weight. A computer code, based on the proposed method, is developed and is applied to design problems using a beam and a plate as test cases. It is confirmed that the vibration energy is reduced at the given exciting frequency. For the beam excited by a frequency slightly less than the fundamental natural frequency, the optimized shape is close to the beam of uniform strength. For the plate, the optimum shape is obtained such that the changes in thickness have the effect of adding a stiffener or a mass
Special cases of friction and applications by F. L Litvin( Book )

1 edition published in 1984 in English and held by 83 WorldCat member libraries worldwide

Computer-aided design of bevel gear tooth surfaces by Shuo Hung Chang( Book )

2 editions published in 1989 in English and held by 80 WorldCat member libraries worldwide

This paper presents a computer aided design procedure for generating bevel gears. The development is based on examining a perfectly plastic, cone- shaped gear blank rolling over a cutting tooth on a plane crown rack. The resulting impression on the plastic gear blank is the envelope of the cutting tooth. This impression and envelope thus form a conjugate tooth surface. Equations are presented for the locus of points on the tooth surface. The same procedures are then extended to simulate the generation of a spiral bevel gear. The corresponding governing equations are presented
Statistical model for asperity contact time fraction in elasthydrodynamic lubrication by Steven M Sidik( Book )

4 editions published in 1978 in English and held by 80 WorldCat member libraries worldwide

Relations for the asperity contact time fraction during elastohydrodynamic (EHD) lubrication of a typical ball bearing are presented. The analysis is based on a two-dimensional random surface model, and actual profile traces of the bearing surfaces were used as statistical sample records. The results of the analysis show that transition from 90 percent contact to 1 percent contact occurs within a dimensionless film thickness range of approximately 4 to 5. This thickness ratio is several times larger than reported in the literature where one-dimensional random surface models were used
On dynamic loads in parallel shaft transmissions I -- Modelling and analysis by Hsiang-Hsi Edward Lin( Book )

3 editions published in 1987 in English and held by 76 WorldCat member libraries worldwide

A model of a simple parallel-shaft, spur-gear transmission is presented. The model is developed to simulate dynamic loads in power transmissions. Factors affecting these loads are identified. Included are shaft stiffness and inertia, load and power source inertia, tooth geometry, tooth stiffness, local compliance due to contact stress, load sharing, and friction. Governing differential equations are developed and a solution procedure is outlined
On dynamic loads in parallel shaft transmissions II -- Parameter study by Hsiang-Hsi Edward Lin( Book )

2 editions published in 1987 in English and held by 74 WorldCat member libraries worldwide

Solutions to the governing equations of a spur gear transmission model, developed in NASA TM-100180 (AVSCOM TM-87-C-2) are presented. Factors affecting the dynamic load are identified. It is found that the dynamic load increases with operating speed up to a system natural frequency. At operating speeds beyond the natural frequency the dynamic load decreases dramatically. Also, it is found that the transmitted load and shaft inertia have little effect upon the total dynamic load. Damping and friction decrease the dynamic load. Finally, tooth stiffness has a significant effect upon dynamic loading: the higher the stiffness, the lower the dynamic loading. Also, the higher the stiffness the higher the rotating speed required for peak dynamic response
Life analysis of multiroller planetary traction drive by John J Coy( Book )

5 editions published in 1981 in English and held by 65 WorldCat member libraries worldwide

A contact fatigue life analysis was performed for a constant ratio, Nasvytis Multiroller Traction Drive. The analysis was based on the Lundberg- Palmgren method for rolling-element bearing life prediction. Life adjustment factors for materials, processing, lubrication and traction were included. The 14.7 to 1 ratio drive consisted of a single stage planetary configuration with two rows of stepped planet rollers of five rollers per row, having a roller cluster diameter of approximately 0.21 m, a width of 0.06 m and a weight of 9 kg. Drive system 10 percent life ranged from 18 800 hours at 16.6 kW (22.2 hp) and 25 000 rpm sun roller speed, to 305 hours at maximum operating conditions of 149 kW (200 hp) and 75 000 rpm sun roller speed. A study was performed to determine the effects of roller diameter and roller center location on life. It was found that an optimum life geometry exists
Comparison of predicted and measured elastohydrodynamic film thickness in a 20-millimeter-bore ball bearing by John J Coy( Book )

5 editions published in 1979 in English and held by 64 WorldCat member libraries worldwide

Transmission efficiency measurements and correlations with physical characteristics of the lubricant by John J Coy( Book )

1 edition published in 1984 in English and held by 59 WorldCat member libraries worldwide

Data from helicopter transmission efficiency tests have been compared to physical properties of the eleven lubricants used in those tests. The tests were conducted with the OH-58 helicopter main rotor transmission. Efficiencies ranged from 98.3 to 98.8 percent. The data was examined for correlation of physical properties with efficiency. There was a reasonable correlation of efficiency with absolute viscosity if the viscosity was first corrected for temperature and pressure in the lubricated contact. Between lubricants, efficiency did not correlate well with viscosity at atmospheric pressure. Between lubricants, efficiency did not correlate well with calculated lubricant film forming capacity. Bench type sliding friction and wear measurements could not be correlated to transmission efficiency and component wear
Summary of drive-train component technology in helicopters by Gilbert J Weden( Book )

1 edition published in 1984 in English and held by 58 WorldCat member libraries worldwide

A review of current helicopters was conducted to determine the technology in the drive-train systems. This paper highlights the design features including reliability, maintainability and survivability characteristics, in transmission systems for the OH-58, UH-1, CH-47, and UH-60 helicopters. In addition, trade-offs involving cost, reliability and life are discussed
Fatigue life analysis for traction drives with application to a toroidal type geometry by John J Coy( Book )

3 editions published in 1976 in English and held by 43 WorldCat member libraries worldwide

Gearing by John J Coy( Book )

3 editions published in 1985 in English and held by 30 WorldCat member libraries worldwide

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. This publication draws together current gear practice and integrates it with recent advances in the technology. 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, not having been treated before. New and more complete methods of power loss prediction as well as an optimum design of spur gear meshes are described. Conventional and new types of power transmission system are presented. (Author)
Life analysis of restored and refurbished bearings by John J Coy( Book )

2 editions published in 1977 in English and held by 21 WorldCat member libraries worldwide

Life analysis of helical gear sets using Lundberg-Palmgren theory by John J Coy( Book )

4 editions published in 1975 in English and held by 19 WorldCat member libraries worldwide

 
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Audience level: 0.61 (from 0.51 for Gearing / ... to 0.73 for Life analy ...)

Languages
English (59)