The main automatic transmission to utilize a torque converter (in place of a fluid coupling) was the Buick Dynaflow, which was launched with the 1948 design year. In ordinary driving, the Dynaflow employed just the top rated gear, relying on the torque multiplication from the torque convertor at reduced speeds. https://gearbox-auto98528.bloguetechno.com/rumored-buzz-on-gearbox-auto-69247799