The initial automatic transmission to implement a torque converter (instead of a fluid coupling) was the Buick Dynaflow, which was introduced with the 1948 model year. In standard driving, the Dynaflow used only the major gear, counting on the torque multiplication with the torque convertor at lower speeds. The Dynaflow https://elliottvcddc.blogsumer.com/33349100/gearbox-auto-an-overview