The very first automatic transmission to employ a torque converter (in lieu of a fluid coupling) was the Buick Dynaflow, which was released with the 1948 design yr. In typical driving, the Dynaflow employed just the prime gear, depending on the torque multiplication with the torque convertor at reduce speeds. https://gearboxauto75307.blog-kids.com/34000578/indicators-on-gearbox-auto-you-should-know