The initial automatic transmission to utilize a torque converter (instead of a fluid coupling) was the Buick Dynaflow, which was launched for the 1948 product 12 months. In regular driving, the Dynaflow applied just the top rated gear, relying on the torque multiplication of your torque convertor at lower speeds. https://jaidenzipux.answerblogs.com/34005460/gearbox-auto-fundamentals-explained