Since the turbine pace lags continuously guiding the impeller (pump) speed, the velocity ratio is less than 1. Therefore There's friction from the transmission fluid which leads to energy losses. The torque converter clutch requires this system even further by addressing one of many inherent inefficiencies of traditional torque converters https://johnathanmerdo.smblogsites.com/33992061/not-known-facts-about-torque-converter-clutch