The Gasoline Automobile Its Design and Construction 1917 VOLUME II Transmission, Running Gear and Control By P. M. HELDT Technical Editor of The Horseless Age Second Edition P. M. HELDT Nyack, N. Y. 1917
Date 1917
PREFACE
During the period that intervened between the original writing of this volume and the present revision, a number of notable evolutions took place in the design of some of the component parts which are dealt with here. The most important of these was undoubtedly the introduction of the helical bevel gear drive. The adoption, of this drive confronted automobile engineers with new problems, chiefly in regard to bearing loads; these are discussed in some detail in the present edition and rules for the calculation of the bearing loads are given. While the bevel-spur and the internal gear drive were both in use at the time the first edition was prepared, only a single firm was prominently identified with each in the United States, so they were not deemed of much importance to warrant special treatment. Since then, however, the internal gear drive has made notable progress in this country and the bevel-spur drive has assumed some importance in England. At the same time additional interest has been aroused in the four wheel drive for military and similar trucks, so it was decided to add a chapter covering these three forms of final drive. The advent of the high speed motor, together with a great increase in the use of unit power plants, resulting in the lengthening of propeller shafts, has compelled designers to give more attention to the problem of critical speeds in shafts. Some matter on this subject has been incorporated in the Chapter on The Bevel Gear Drive and Rear Axle, the theory of critical speeds being explained and rules for their calculation given. Another branch of automobile engineering in which great commercial development has taken place during the past four years is that relating to the worm drive. The chapter devoted to this subject has been largely rewritten and brought up to date. Minor additions and changes have been made throughout the book, and a number of typographical and other errors that occurred in the first edition have been corrected. For pointing out such errors the author wishes to thank some of his readers.
It may appear that in the chapters on the Sliding Change Gear and on Rear Axles, the annular ball bearing receives more attention than is warranted by the scale of its present day use. Owing at least in part to the interruption of imports of ball bearings from Europe, roller bearings now predominate largely in automobile construction. The problems of mounting, however, are very much the same as with ball bearings, and numerous examples of mounting roller bearings are given in the plates at the end of the book as well as in 'the text illustrations. In the most expensive cars the annular ball bearing still retains a prominent place, and it was, therefore, not deemed necessary to rewrite this part of the work. As nearly all of the old plates had to be discarded it was decided to incorporate the plates in the book itself. Chassis views are shown for the most part in half tone, so the line cuts show only chassis components and these can be presented on a sufficiently large scale on a 5j4 x 8j4 sheet. THE AUTHOR
610 pages
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