The 1st automatic transmission to employ a torque converter (in place of a fluid coupling) was the Buick Dynaflow, which was released to the 1948 model calendar year. In ordinary driving, the Dynaflow applied just the major gear, relying on the torque multiplication with the torque convertor at lessen speeds. https://gearboxauto87417.howeweb.com/34792157/facts-about-gearbox-auto-revealed