In Introduction to the Kinematic Geometry Gear Teeth, Allan H. Candee presents information and explanations about gear-tooth contact in a form useful for reference and suitable for study.

The scope of this book is restricted to gears on parallel axes with straight teeth parallel to the axes, namely spur gears, in which the same profile curve exists all along a tooth. The basic problem concerns CONTACT between tooth profiles in a plane, and all related problems can be solved by two-dimensional plane geometry and kinematic geometry. Tooth generation and tooth design are treated as an important part of gear design. The important feature of the book is METHOD. None of the problems treated is new; but the solutions are obtained by thinking geometrically in a way that will appeal to the practical-minded.

A graphical method is employed that consists of geometrical constructions by lines and points, combined with numerical calculations of distances and angles. Although principles and methods have long been known that cover all phases of gear-tooth action, modern ideas in the geometrical kinematics of mechanisms are applied in practical ways that in many instances are original with the author. Considerable use is made of the ideas of instant centers and centers of curvature. By recognizing that in practical work the information wanted often consists of small differences between tooth profiles, resulting from small variations and changes, diagrams are used in which attention is directed to the small distances rather than to the much larger dimensions like diameters, radii, and center distance. It is then possible to derive simple formulas that yield acceptably accurate values by comparatively short arithmetical calculations. General equations of curves are shown only when they are easily derived and simple in form.

Tables of recently computed coordinates of points on the involute of a circle and on involute tooth profiles are presented in an Appendix. Rectilinear coordinates for laying out a profile curve are referred to the tangent line and the normal line at a chosen point on the profile. Circular coordinates, consisting of a value x along a chosen circle and a value y in the radial direction, form two sides of an "involute triangle" and simplify determinations of tooth thickness, backlash, and the effects of change of center distance.

Introduction to the Kinematic Geometry of Gear Teeth should be helpful to all individuals interested in toothed gearing, namely: the Designing Engineer, concerned with the manufacture of gears and gear-producing equipment; the Gear Designer and the Gear Calculator, responsible for the design and specifications of gears; the Production Superintendent and the Department Foreman, responsible for the operation of gear-manufacturing equipment and the procedures necessary to obtain satisfactory results; the Professor and the Instructor in Mechanical Engineering, teaching the kinematics of mechanisms as applied in toothed gears; the Student in Mechanical Engineering, learning the applications of geometry and kinematics in the design and generation of gear teeth.