Gear Technology Basics – Design Aspects
History, Nomenclature, Types, Tooth Action, and Failure Modes/Prevention
Develop your understanding of the history, basic gear tooth nomenclature, types of gears, gear arrangements, theory of gear tooth action, and failure modes and prevention. This course was updated and expanded to comprehensively cover important topics relating to gear system design consideration.
Raymond J. Drago is Chief Engineer for Drive Systems Technology, Inc., a mechanical power transmission consulting organization that he founded in 1976. Drago holds a master’s degree in structural engineering from Drexel University (1980), a master’s degree in engineering from ... read more
Benefits and Learning Outcomes
- Build your knowledge of modern gear system design and analysis
- Distinguish between types of gears and gear arrangements
- Discuss theory of gear tooth action and derive parameters as they’re presented
1.1 Introduction – A brief introduction of the material to be presented and its relation to the overall two-part Fundamentals of Gear Design Seminar Pair is discussed.
1.2 History – A short chronology of the development of gear technology and its role in man’s development through the ages is covered in capsule form.
1.3 Basic Gear Tooth Nomenclature – In order to facilitate the discussion of gear technology, a brief presentation of the terminology and nomenclature unique to gearing is presented. This presentation includes both geometric definitions and an overview of the major gear-related terms used in the remainder of the presentation.
1.4 Types of Gears – The major types of gears, their uses and limitations, and the relative advantages of each are discussed. The types of gears are divided into three classifications based on the relation of their axes: parallel, coplanar intersecting and noncoplanar nonintersecting. Special, noncircular gear types are also covered.
1.5 Gear Arrangements – In order to better understand the functioning of gears within an overall drive system, a broad review of the manner in which gears may be used in specific types of drives, including simple reductions, epicyclic configurations, Harmonic drives, etc., is presented in a qualitative manner with illustrative examples.
1.6 Theory of Gear Tooth Action – Geometry and kinematic concepts for simple parallel axes gears are developed from basic theory in order to provide a foundation for the study of more complex gear types. Concepts including speed ratio equation development, sliding and rolling velocities, approach and recess action, basic involute geometry, backlash and tooth thickness relations, contact ratio, limits of contact, the Law of Conjugate Motion, and other topics are derived and presented. All parameters discussed are fully derived and not simply presented as end results.
1.7 Failure Modes and Prevention – Only by thoroughly understanding the manner in which gears can fail under a wide variety of operating conditions can the designer guard against such failures. An extensive discussion of all common and many unusual types of failures, their causes and methods available to prevent them both in the design and hardware stages is presented. The presentation is organized into nine main classifications. The overall phenomena that define each group are described in general and specific subcases of each group. Excellent photographs illustrate each concept and the instructor’s wide experience is brought into play in the form of detailed discussions of specific failure investigations to further emphasize many of the modes discussed. Many hardware samples are used to illustrate the various failure modes.
A knowledge of geometry, trigonometry, and elementary algebra is required. Basic strength of materials is helpful but not essential.