The first automatic transmission to work with a torque converter (instead of a fluid coupling) was the Buick Dynaflow, which was launched for the 1948 model calendar year. In ordinary driving, the Dynaflow used only the prime equipment, relying on the torque multiplication on the torque convertor at reduced speeds. https://gearboxauto63950.blogocial.com/gearbox-auto-an-overview-69890944