To most mechanics a gear is a gear."A yellow primrose by the shore, A yellow primrose was, to him And it was nothing more;"And, in fact, the gear is often a gear and nothing more, sometimes barely that. But, if the mechanic will look beyond the tips of his fingers, he will find that it can be something more; that it is one of the most interesting objects in the field of science research, and not the simplest one; that it has received the attention of may celebrated mathematicians and engineers; and that the study of its features will not only add to his practical knowledge, but also to his entertainment. There is an element in mathematics, and in its near relative, theoretical mechanics, that possesses an educating and disciplining value beyond any capacity for earning present money. The thinking, inquisitive student of the day is the successful engineer or manufacturer of the future. The book is filled with wonderful turn of the century illustrations of gear wheels and gear cutting of every description.

This book provides a compact history of gears, by summarizing the main stages of their development and the corresponding gradual acquisition of engineering expertise, from the antiquity to the Renaissance and the twentieth century. This brief history makes no claim to be exhaustive, since the topic is so extensive, complex and fascinating that it deserves an entire encyclopedia. Despite its brevity, the book debunks a number of popular misconceptions, such as the belief that the first literary description of a gear was supplied by Aristotle. It disproves not only this myth, but also other peremptory statements and/or axiomatic assumptions that have no basis in written documents, archaeological findings or other factual evidence. The book is chiefly intended for students and lecturers, historians of science and scientists, and all those who want to learn about the genesis and evolution of this topic.

A Gear Chronology A Review In his foreword to A Gear Chronology book, author William P. Crosher dedicates his work to "those engineers and organizations that give freely of their time and experience to develop standards and technical conferences that are so crucial to the progress of the gear industry." In my experience, Crosher demonstrates this same desire to know all he can about his profession, and to contribute to its continued growth and evolution in an ongoing and proactive manner. As complicated and technical as some of the topics he discusses can be, Crosher writes in a manner that is straightforward, accessible, and informative. In other words, he harnesses the same approach utilized by any good teacher in finding a way to engage his audience while at the same time conveying valuable information. He achieves this by providing historical and peripheral material that brings the subject under discussion to life. In chapters devoted to the fundamentals of gearing, definitions of gear elements, materials, and processes such as heat treating, the author builds a solid foundation for later chapters on subjects including spur, helical, and worm gear design, gear manufacturing and inspection, lubrication properties, and failure modes, along with an analysis of those examined. Topics are explored fully and explained clearly, with a wealth of helpful illustrations in support of the text. References and resources are listed at the end of the book, including contact information for associations that can assist in the reader's continued professional growth. The former director of the National Conference on Power Transmission, as well as former chairman of the American Gear Manufacturers Association's Marketing Council and Enclosed Drive Committee, Crosher was resident engineer-North America for Thyssen Gear Works, and later at Flender Graffenstaden. He is author of the book Design and Application of the Worm Gear and longtime writer of the "Tooth Tips" column that appears each month in the pages of Gear Solutions magazine, which is published by Media Solutions, Inc. As editor I can attest to the fact that his work generates a high degree of reader response, and that he is both known and respected in the gear-manufacturing industry around the world. It is an honor to be in a position to share his knowledge and expertise with our readers, and to have the opportunity to comment on his latest professional endeavor. Russ Willcutt, Editor Gear Solutions Magazine [email protected] www.gearsolutions.com (800) 366-2185 ext. 205

Written by a leading expert, Theory of Gearing: Kinematics, Geometry, and Synthesis, Second Edition is intended for engineers and researchers in the field of gear design, gear production, gear inspection, and application of gears. It focuses on the scientific theory of gearing, in all its aspects, and its application to new gear types and designs.