The initial automatic transmission to use a torque converter (in place of a fluid coupling) was the Buick Dynaflow, which was introduced for your 1948 design 12 months. In ordinary driving, the Dynaflow utilised only the top gear, depending on the torque multiplication with the torque convertor at reduce speeds. https://gearbox-auto08639.dbblog.net/7459502/facts-about-gearbox-auto-revealed