The initial automatic transmission to make use of a torque converter (as opposed to a fluid coupling) was the Buick Dynaflow, which was introduced for that 1948 model calendar year. In usual driving, the Dynaflow employed just the top rated gear, depending on the torque multiplication on the torque convertor https://gearbox-auto64184.answerblogs.com/34363288/new-step-by-step-map-for-gearbox-auto