Effect of Additives and Oxidation on Transmission Clutch Materials Available to Purchase

In 1959, more than 75% of cars produced in the U.S.A. were fitted with automatic transmissions, and the Hydra‐Matic system is in wide use. In the case of this transmission, smoothness of operation is particularly important with respect to the 2–3 shift, which is the only forward shift that is accomplished by engagement of clutch plates. In a paper to the Society of Automobile Engineers, at the Summer Meeting in June, John J. Rodgers and Merrill L. Haviland, of the General Motors Research Laboratories, presented the results of investigations aimed at clarifying the manner in which additives modify the friction characteristics of automatic transmission fluids, as well as the effect of an inert atmosphere on transmission shift performance.