For many years, when gear engineers have been confronted with tough problems either in the field or on the drawing board, one of the inevitable suggestions has been, "Ask Darle Dudley," or "Check the Dudley book." That's not surprising. With more than fifty years' experience in gear design and credits for five books (with translations in French, German, Spanish and Italian), numerous papers, lectures, and patents, and a worldwide reputation as a gear expert, Darle Dudley's position as one of the men to ask when dealing with knotty gear problems is unassailable.