The initial automatic transmission to use a torque converter (instead of a fluid coupling) was the Buick Dynaflow, which was released for the 1948 model year. In typical driving, the Dynaflow made use of just the major equipment, depending on the torque multiplication with the torque convertor at lower speeds. https://andypvwws.mybuzzblog.com/13869513/detailed-notes-on-gearbox-auto