The first automatic transmission to use a torque converter (instead of a fluid coupling) was the Buick Dynaflow, which was released to the 1948 model year. In ordinary driving, the Dynaflow used just the prime gear, depending on the torque multiplication from the torque convertor at reduced speeds. The Dynaflow https://kameronbmruv.idblogmaker.com/33275763/new-step-by-step-map-for-gearbox-auto