Modern torque converters use electro hydraulic Handle to the lock-up clutch. The hydraulic circuit which locks/unlocks the torque converter clutch is managed applying hydraulic valves. The valves are actuated directly or indirectly by solenoids. Torque converter equations of motion are ruled by Leonhard Euler's eighteenth century turbomachine equation: Present day https://torque-converter-clutch49360.kylieblog.com/34529914/the-torque-converter-clutch-diaries