The very first automatic transmission to employ a torque converter (as opposed to a fluid coupling) was the Buick Dynaflow, which was launched for your 1948 model year. In ordinary driving, the Dynaflow utilised just the leading gear, depending on the torque multiplication on the torque convertor at reduce speeds. https://daltonjgzpb.newsbloger.com/34413026/the-2-minute-rule-for-gearbox-auto