Using the 3-passage torque converter, two passages are useful for transmission oil (ATF) stream throughout the torque converter and for clutch cooling, although the 3rd passage is utilised independently to manage the lock and unlock from the clutch. In the two-passage torque converter clutch actuation technique (as in the images https://torqueconverterclutch75296.blogozz.com/33118111/torque-converter-clutch-fundamentals-explained