The 1st automatic transmission to make use of a torque converter (rather than a fluid coupling) was the Buick Dynaflow, which was launched for that 1948 model yr. In normal driving, the Dynaflow employed just the leading gear, depending on the torque multiplication with the torque convertor at decreased speeds. https://jaredrsnic.blogadvize.com/41660929/not-known-facts-about-gearbox-auto