The initial automatic transmission to work with a torque converter (in place of a fluid coupling) was the Buick Dynaflow, which was introduced to the 1948 model year. In typical driving, the Dynaflow employed only the prime gear, relying on the torque multiplication from the torque convertor at reduce speeds. https://gearboxauto65296.ttblogs.com/13814173/the-smart-trick-of-gearbox-auto-that-nobody-is-discussing