With regards to the variety of passages (ports) for controlling the oil movement with the torque converter clutch, there are lots of different types of torque converters: This can be a aspect past what an easy fluid coupling supplies, which could match rotational pace but won't multiply torque. Fluid-coupling–based torque https://torque-converter-clutch64185.blogoxo.com/34144519/torque-converter-clutch-fundamentals-explained