The initial automatic transmission to use a torque converter (as opposed to a fluid coupling) was the Buick Dynaflow, which was released with the 1948 product 12 months. In typical driving, the Dynaflow employed just the leading gear, relying on the torque multiplication from the torque convertor at reduce speeds. https://marioizlve.wssblogs.com/33749045/not-known-details-about-gearbox-auto