A lock-up torque converter contains a built-in locking clutch system. When the transmission senses a selected speed or motor RPM, the torque converter will use the clutch to lock in a direct connection among the input and output shafts for far better effectiveness. In a torque converter you'll find at https://torqueconverterclutch09641.pointblog.net/torque-converter-clutch-for-dummies-77735838