The primary automatic transmission to employ a torque converter (instead of a fluid coupling) was the Buick Dynaflow, which was released with the 1948 model year. In normal driving, the Dynaflow made use of just the major gear, counting on the torque multiplication from the torque convertor at lessen speeds. https://spencernxaaz.blogstival.com/55960552/gearbox-auto-things-to-know-before-you-buy