Patent ID: 8381888

Claim:
A power transmission device ( 1 ) for power transmission between an engine and a power output, comprising: an input (E); an output (A); a hydrodynamic component ( 3 ); shiftable clutch device ( 6 ) for at least partially bypassing said hydrodynamic component ( 3 ) having: a first piston element ( 10 ), that can be pressurized with hydraulic medium; and a second rotatable piston element ( 12 ) disposed in an axial direction between said piston element ( 10 ) and the hydrodynamic component and connected to the first piston element such that rotation of the second piston element is locked to rotation of the first piston element, wherein: the first piston element is axially displaceable to open and close the shiftable clutch device; and, the second piston element remains free of contact with the first piston when the shiftable clutch device is closed.