The 1st automatic transmission to use a torque converter (as opposed to a fluid coupling) was the Buick Dynaflow, which was launched for that 1948 product yr. In ordinary driving, the Dynaflow used just the top rated gear, depending on the torque multiplication of your torque convertor at reduce speeds. https://gearbox-auto98406.blogdal.com/34600640/considerations-to-know-about-gearbox-auto