The 1st automatic transmission to implement a torque converter (rather than a fluid coupling) was the Buick Dynaflow, which was introduced to the 1948 model yr. In normal driving, the Dynaflow made use of only the leading equipment, relying on the torque multiplication from the torque convertor at decreased speeds. https://gearbox-auto24455.blogtov.com/14285826/the-basic-principles-of-gearbox-auto