The 1st automatic transmission to utilize a torque converter (instead of a fluid coupling) was the Buick Dynaflow, which was launched with the 1948 product yr. In regular driving, the Dynaflow made use of just the leading gear, depending on the torque multiplication of your torque convertor at decreased speeds. https://gearboxauto39517.blogerus.com/56298092/the-basic-principles-of-gearbox-auto