Abstract
Since the inception of the automobile, steady development has resulted in the evolution of the transmission unit from the manually operated open sliding gear train to the modern compact fully automatic transmission. In this address the author has endeavoured to trace the various stages through which this development has passed. Throughout the period the general tendency has been towards a more compact unit and all have contributed, to some degree, in reducing to the minimum the skill required in gear changing. Space has not permitted of a detailed examination of all the mechanisms that have been produced and only a brief review of the general trend has been possible. In addition to the better known developments, descriptions have also been included of some of the more unorthodox designs that were in production for many years.
In Great Britain the syncromesh gear box is firmly established for both cars and trucks but in the United States of America this type of transmission is now almost obsolete and the automatic transmission is practically in universal use. The two main types of automatic transmission—viz. the automatically-changed four-speed fixed ratio unit used in conjunction with a fluid coupling and the infinitely variable ratio hydraulic torque converter—are dealt with in some detail as an appreciation of the present state of the art in the U.S.A. is indicative of the direction that future development in Great Britain will almost inevitably take.
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