The control of the oil pressure inside the lock-up clutch is finished via two valves: the relay valve along with the sign valve. In this sort of arrangement the sign valve controls the pressure on a single aspect from the relay valve, which controls the stress within the lock-up clutch. https://torqueconverterclutch76306.timeblog.net/70034174/a-secret-weapon-for-torque-converter-clutch