TEETH OF WHEELS With the Theory and the use of D. VAN NOSTRAND, PUBLISHER, 1888. Preface to the Second Edition. The first edition of this little volume resulted from an effort to place in the hands of machine builders simple and improved facilities for obtaining correct gearing, and that the effort was appreciated to some extent is evinced by the fact of the exhaustion of that edition. In the present edition improvements and additions have been made for the purpose of the better securing the original object, all tending to give the subject matter a more practical bearing. Correct gear teeth are essential for the economic transmission of power, as well as extremely desirable for avoiding need、less rattling. Many of the cast gears introduced into mills and factories may properly be termed rattling machines, and simply because the designer had too vague a conception of the theory of gearing, or because he sought to avoid the trouble of laying them out. If this manual, and the odontograph, shall contribute toward relieving these inconveniences, the object sought, when the instrument was devised, and an effort made to present it in convenient form for use, will be realized. The Templet Odontograph described in the second part received an award at the Centennial Exposition of "76, where it was first presented to the public, a testimonial which its somewhat extended use has since justified. A new and enlarged table, for use in connection with the instrument, is given in this edition, and substituted for several tables of the former edition, a table which covers all cases of epicycloidal and involute gearing; but to render the use of the instrument most convenient in practice, numerous tables are furnished with the instrument to cover special systems of gearing, but which tables are not of sufficient interest to this volume to be included in it. OHIO STATE UNIVERSITY, S. W. R. April 4th, 1888. |