Considering that the turbine speed lags constantly driving the impeller (pump) speed, the pace ratio is under one. Therefore There exists friction from the transmission fluid which ends up in energy losses. Slippage consumes electrical power over the coupling stage. Locking the converter shell for the turbine shaft prevents this https://torque-converter-clutch81456.blogunok.com/34161400/the-basic-principles-of-torque-converter-clutch