The 1st automatic transmission to use a torque converter (in lieu of a fluid coupling) was the Buick Dynaflow, which was introduced for your 1948 product 12 months. In regular driving, the Dynaflow made use of only the major gear, depending on the torque multiplication from the torque convertor at https://mariomuxae.blogsumer.com/33349394/the-smart-trick-of-gearbox-auto-that-nobody-is-discussing