The first automotive software on the lock-up principle was Packard's Ultramatic transmission, released in 1949, which locked up the converter at cruising speeds, unlocking if the throttle was floored for quick acceleration or as being the car slowed. While using the 3-passage torque converter, two passages are employed for transmission https://troyltals.blogofchange.com/34568643/details-fiction-and-torque-converter-clutch