The primary automatic transmission to use a torque converter (as opposed to a fluid coupling) was the Buick Dynaflow, which was introduced for the 1948 product calendar year. In regular driving, the Dynaflow utilized just the major gear, depending on the torque multiplication with the torque convertor at decrease speeds. https://gearboxauto97418.bloggactif.com/35051633/gearbox-auto-an-overview