The first automatic transmission to utilize a torque converter (in place of a fluid coupling) was the Buick Dynaflow, which was introduced with the 1948 product calendar year. In typical driving, the Dynaflow applied just the leading gear, counting on the torque multiplication on the torque convertor at lower speeds. https://juliusrwabd.dailyhitblog.com/39564316/a-review-of-gearbox-auto