The main automatic transmission to employ a torque converter (rather than a fluid coupling) was the Buick Dynaflow, which was launched for that 1948 product yr. In normal driving, the Dynaflow made use of only the top equipment, relying on the torque multiplication in the torque convertor at reduced speeds. https://messiahuefeg.dm-blog.com/34165069/gearbox-auto-can-be-fun-for-anyone