The 1st automatic transmission to employ a torque converter (instead of a fluid coupling) was the Buick Dynaflow, which was launched with the 1948 design year. In normal driving, the Dynaflow made use of just the top gear, counting on the torque multiplication of your torque convertor at lessen speeds. https://gearbox-auto76307.onzeblog.com/33820659/about-gearbox-auto