The very first automatic transmission to implement a torque converter (rather than a fluid coupling) was the Buick Dynaflow, which was launched with the 1948 product calendar year. In regular driving, the Dynaflow used just the leading equipment, depending on the torque multiplication of the torque convertor at decrease speeds. https://martinoybef.blogkoo.com/5-simple-statements-about-gearbox-auto-explained-53523952