piston 58 which is supported for axial displacement along axis 12 piston is sealed at its outer periphery by a dynamic seal 60 to an inner surface of housing 26 and is sealed at its inner periphery by a dynamic seal 62 thereby defining a sealed volume 64 located between piston 58 and housing 26 when volume 64 is pressurized through clutch apply passage 66 capy piston 58 moves leftward forcing friction discs 30 and clutch plates 38 into mutual frictional contact thereby engaging bypass clutch 28 when clutch 28 is engaged the engine and turbine 16 are mechanically interconnected and driveably connected to the transmission input shaft 24 when lockup clutch 28 is disengaged the turbine 16 and engine are mechanically disconnected and the turbine is hydrokinetically driven by the impeller 14 atf fills the toroidal volume in which the turbine 16 impeller 14 and stator 18 rotate at converter charge pressure ccl through an annular passage 70 between input shaft 24 and stator support 20 atf exits torque converter 10 at converter discharge pressure cout through passage 72 an annular passage between stator support 20 and a converter drive shaft 76 on which impeller 14 is supported fig2 illustrates a hydraulic system for controlling converter charge limit pressure ccl of the fluid that enters the toroidal chamber of converter 10 through line 70 converter apply pressure capy that controls converter clutch 28 and fluid exiting the converter cout through line 72 the torque transmitting capacity of clutch 28 may vary among 1 a locked condition in which clutch 28 is applied but may be slipping 2 a hard locked condition in which the clutch is applied with zero.