AUTOMATIC TRANSMISSIONS IN AMERICA by Charles A. Chayne Vice President Engineering Staff General Motors Corporation Downloaded from SAE International by Columbia Univ, Thursday, December 06, 2018Acknowledgment is hereby made to the following for their courtesy in providing photographic material: Allis Chalmers Manufacturing Company - Milwaukee, Wisconsin Budd Company - Philadelphia, Pennsylvania Chrysler Corporation - Detroit, Michigan Earle Equipment Company - Detroit, Michigan Euclid Road Machinery Company - Cleveland, Ohio Ford Motor Company - Detroit, Michigan Fuller Manufacturing Company - Kalamazoo, Michigan Packard Motor Car Company — Detroit, Michigan Studebaker Corporation - South Bend, Indiana Appreciation is also extended to General Motors Division Engineers and to Messrs. Oliver K. Kelley, Gilbert K. Hause and Kenneth E. Brooker for their assistance in the preparation of the material. Downloaded from SAE International by Columbia Univ, Thursday, December 06, 2018Ever since the adoption of the internal combustion engine for automotive use, industry has conducted a constant search for a suitable transmission to over­ come the undesirable characteristics of the engine. A transmission with infinitely variable ratio and fully automatic operation of close to one hundred per cent efficiency would be the optimum answer. Until it has been evolved in a durable, compact, and low-cost unit which is easily maintained, the search will go on. For two decades, industry in the United States has been seriously at work developing suitable automatic drive mechanisms for many different uses of the internal combustion engine. The development work has been in varied fields of transportation and governed generally by the requirements set by the specific need of each field, the indicated commercial value of such a device, and the apparent difficulty of accomplishing a satisfactory result. Technically speaking, the high-powered American passenger-car has the least need for an automatic transmission as far as its performance is concerned. The problem also presents so many cost, weight, and size limitations, together with conflicting requirements for performance, pleasability, and efficiency, as to make it an extremely difficult job. However, the multi-billion dollar passenger- car industry offers the greatest promise of commercial rewards for any sensational new feature or development. The greater part of all engineering effort, therefore, has been expended in developing drives for passenger-cars. Downloaded from SAE International by Columbia Univ, Thursday, December 06, 2018The task is not simple and the requirements are many. The passenger-car transmissions must satisfy the average owner-driver. What pleases him most is his own idea of the best combination of reliability, noiselessness, smooth performance, and flashy acceleration when needed. He wants fully automatic normal driving with easily operating, smoothly acting forward and reverse controls; reasonable safety controls such as engine braking and accidental shift inhibitors; efficiency as it affects gas economy; and above all, a reasonable initial cost. Obviously, when so many considerations have to be weighed for the best compromise in determining the design, there are bound to be many differences of opinion as to which is the best design in passenger- car automatic transmissions. Any design, to be of any success at all, must satisfy a fair minimum in all of these requirements. Many attempts have been made to meet these demands in various ways. The early attempts to the solution of this problem produced the Owen Magnetic Electrical Drive and the Carter Car Friction Drive, which were both produced in America. See Figure 1 and 2. Both of these devices enjoyed some commercial success, but they failed to qualify for the more keenly competitive era tha