Thesis (M.S.)--Virginia Polytechnic Institute, 1966. / Vita. Abstract. Includes bibliographical references (leaves 195-199). Also available via the Internet.

This thesis is a small part of a much larger work, the aim of which is to continue the transition from gear theory to gear practice. The thesis deals with some aspects of the testing and theoretical development of equiangular and plain polyangular gears respectively. Initial prototypes of the equiangular spatial involute gearing, a small subset of a general spatial involute gear set, developed in previous works are to be tested for both function and form. The tests, based on the principles of the single flank gear tester, investigate constancy of transmission ratio and use both electronic and mechanical means. The former of these highlights the shortcomings of some aspects of the experimental set up. Algebraic expressions are also developed for plain polyangular gearing, a more general form of spatial involute gearing. These equations demonstrate the links to the underlying kinematic principles and are, consequently, more robust. This is verified by their application to both the equiangular and plain polyangular cases. The expressions were checked by comparing their results to graphical and numerical models developed concurrently with the algebraic expressions. Initial investigations are also undertaken into turning the mathematical theory into gear machining theory. / Master of Engineering (Hons.)

Thesis (award) -- University of Western Sydney, 2005. / Includes bibliography.

Thesis (M.S.)--Ohio State University, 2007. / Includes bibliographical references (leaves 148-152). Available online via OhioLINK's ETD Center

An interactive program is presented which enhances the design of external spur gears cut by a hob. The program code calculates the geometry of an involute spur gear with trochoidal fillets and then uses the Graphical Kernel System (GKS), CADAM, and MOVIE.BYU to represent and display the gear. GKS, an international standard, is used to represent the gear in two dimensions; while the CAD/CAM system CADAM and the software package MOVIE.BYU accurately create wireframe geometric design models in three dimensions. Examples of the input parameters needed and each of the software packages in use are shown and explained. / M.S.

The problem of the deflection of spur gear teeth has been previously investigated analytically by several authors. Two of the papers dealing with this topic were written by Timoshenko and Baud (18)t and Marin and Shenk (11). Both papers employ the cantilever beam approach in which the spur gear tooth is represented as a rigidly supported, cantilever beam of uniform thickness tapered in the plane of load application. Deflection is considered to be caused by bending moment, shearing force, and Hertzian pressure at the point of load application. Two additional papers were written by Weber (25) and Attia (3) in which the actual involute gear tooth was considered to be an elastically supported cantilever beam rather than rigidly clamped at the root of the tooth. Likewise, circumferential deformation of the gear body was considered. However, the derived equations for the total deflection due to these effects are exceedingly complicated and require the use of numerical methods for their solution since some of the equations are in integral form. / Master of Science

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 211-217).

A study of the bending stresses in a pair of meshed spur gears using the finite element method is presented. The models analyzed were in the shape of a circular gear with five teeth or a five-tooth rack. A unit torque (1 lbf-ft) was applied as the form of nodal forces on the nodes around the bore hole of the driver pinion. The nodes around the bore hole of the driven gear (or the nodes along the back of the driven rack) were fixed. In order to transmit the power from the driver pinion to the driven gear (or rack), the points in contact were made coincident. Seven model groups with same diametral pitch (1.0), addendum (1.0 in.), dedendum (1.3 in.), pressure angle (20°) and hob tip radius (0.35 in.) but with varying numbers of teeth on the pinion and gear were analyzed to compute the tensile stress variation in the root fillet during the duration of contact. A model for predicting the tensile stress variation at the root fillet during the duration of contact has been created. The results were compared with AGMA and other results with agreement for the peak within 3%. / M.S.

M. Tech. (Department of Metallurgical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / To meet the ever-increasing demand for maintenance of gear systems, industrial companies have traditionally depended on the shutdown of the machines before processing the fault diagnosis. Nowadays, online monitoring has proven to be effective in terms of machine state analysis and fault prediction. However, the application of such a technique in the analysis of combined multiple nonlinear faults is still a subject of research. The vibration signature of a coexisting nonlinear crack and pit in two-stage gear system is unknown, it can be regarded as one of the most difficult problems to extract and diagnose. Additionally, incorporating both a crack and a pit into numerical models is a time-consuming process that demands a breadth of mechanical understanding. Diagnostics of faulty gears, on the other hand, can be performed in the time and frequency domain or in the Time-Frequency domain, depending on the complexity of the vibration. Non-linear and non-stationary phenomena (Features) occur when repeated pitting and cracking faults occur, reducing the reliability of standard signal processing methods (Gear displacement and Fast Fourier Transform). This thesis solves each of these shortcomings by developing an eight-degree-of-freedom (DOF) gear model with a breathing crack and multiple pitted gear teeth. The identified spur-gear model enabled the investigation of the crack and pitting signatures and their effect on the ensuing vibrations independently of the action of other system components. Additionally, when pitting and cracking coexist, the study was conducted to determine the influence of such a failure on the transmission system. Theoretical results indicated that the presence of pitting and crack in the tooth of the gear resulted in a decrease in mesh stiffness. Additionally, the influence of the breathing pitting and crack results in material fatigue, which results in the generation of a random term in the vibration signal. To corroborate the acquired results, several experimental tests on a spur-gear test rig with a defined pit and crack size range were undertaken under a variety of conditions. In comparison to the presented methodologies, theoretical and experimental results indicate that 3D Frequency-RPM analysis is the most sensitive and resilient method for the early detection and identification of pit and crack faults. Furthermore, when crack or pit faults are studied individually, the STFT analysis yields interesting results. The feature analysis revealed that, when using the Time-Frequency technique, the crack and pit combination in a two-stage gear system is a priori more efficient than the other options.