The initial automatic transmission to make use of a torque converter (rather than a fluid coupling) was the Buick Dynaflow, which was introduced with the 1948 product year. In standard driving, the Dynaflow applied just the prime equipment, relying on the torque multiplication from the torque convertor at lessen speeds. https://deanrwvsp.blogitright.com/34275303/gearbox-auto-an-overview