The primary automatic transmission to employ a torque converter (as an alternative to a fluid coupling) was the Buick Dynaflow, which was released with the 1948 model year. In typical driving, the Dynaflow applied just the top gear, relying on the torque multiplication in the torque convertor at decreased speeds. https://gearboxauto76428.activoblog.com/37204829/gearbox-auto-for-dummies