From Gear Geometry and Applied Theory, Second Edtion

21.1 INTRODUCTION

Spiral bevel gears have found broad application in helicopter and truck transmissions and reducers for transformation of rotation and torque between intersected axes. Design and stress analysis of such gear drives has been a topic of research by many scientists including the authors of this book [Krenzer, 1981; Handschuh & Litvin, 1991; Stadtfeld, 1993, 1995; Zhang et al., 1995; Gosselin et al., 1996; Litvin et al., 1998a, 2002a; Argyris et al., 2002; Fuentes et al., 2002]. Reduction of noise and stabilization of bearing contact of misaligned spiral bevel gear drives are still very challenging topics of research although manufacturing companies [Gleason Works (USA), Klingelnberg Oerlikon (Germany Switzerland)] have developed skilled methods and outstanding equipment for manufacture of such gear drives.

The conditions of meshing and contact of spiral bevel gears depend substantially on the machine-tool settings applied. Such settings are not standardized but have to be determined for each case of design, depending on the parameters of the gears and generating tools, to guarantee the required quality of the gear drives. This chapter covers an integrated approach for the design and stress analysis of spiral bevel gears that has been developed by the authors of the book and their associates. The approach provides the solution to the following problems:

  1. Determination of machine-tool settings for generation of low-noise stable bearing contact spiral bevel gear drives.

  2. Computerized analysis of meshing and contact of gear tooth surfaces.

  3. Investigation of formation of bearing contact and...

Copyright Faydor L. Litvin and Alfonso Fuentes 2004 under license agreement with Books24x7

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Gears

Gears are rotating mechanical devices employing 'teeth' in order to transmit torque between separate axes. Two or more cooperating gears are called a transmission and can produce a mechanical advantage by changing speed, torque or rotation direction.

Bevel and Miter Gears

Bevel gears are gears designed to transmit motion between intersecting axes. Perpendicular arrangements are most common, but bevel gears can be manufactured for nearly any angle. The teeth bearing surface of the gear, or surface pitch, is conically shaped or tapered. Miter gears are bevel gears manufactured in a 1:1 ratio, with the same number of teeth on mating gears and with perpendicular axes.

Worms and Worm Gears

Worms and worm gears are gear sets that offer high gear reduction and torque multiplication with a small footprint. A worm drive is a cylindrical gear with a shallow spiral thread that engages the worm gear in a non-intersecting, perpendicular axes configuration.

Hypoid Gears

A hypoid gear is a style of spiral bevel gear whose main variance is that the mating gears' axes do not intersect. The hypoid gear is offset from the gear center, allowing unique configurations and a large diameter shaft. The teeth on a hypoid gear are helical, and the pitch surface is best described as a hyperboloid. A hypoid gear can be considered a cross between a bevel gear and a worm drive.

Metric Gears
Metric gears are defined by module, which designates the center-to-center distance between successive teeth. This criteria of gear selection is used in countries which have adopted the metric system and is intended to standardize gear selection.

Topics of Interest

22.1 INTRODUCTION Hypoid gear drives have found a broad application in the automotive industry for transformation of rotation between crossed axes. Enhanced design and generation of hypoid gear...

17.1 INTRODUCTION Wildhaber [1926] and Novikov [1956] have proposed helical gears based on generation by circular arc rack-cutters. The difference between the two inventions is that the gear tooth...

16.1 INTRODUCTION Involute helical gears are widely applied in the industry for transformation of rotation between parallel and crossed axes. Figure 16.1.1 shows an involute helical gear drive with...

15.1 INTRODUCTION Involute gears, spur and helical ones, are widely used in reducers, planetary gear trains, transmissions, and many other industrial applications. The level of sophistication in the...

14.1 INTRODUCTION Cycloidal gears (Chapter 13) and involute gears (Chapters 10, 11, 14, 15, and 16) have different areas of application. This chapter covers involute gears with parallel axes, whose...

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