Patent ID: 7350633

Claim:
A power transmission having a transmission case and a torque-transmitting mechanism and comprising; a generally annular apply piston movable for selectively engaging the torque-transmitting mechanism, wherein said apply piston is characterized by a first circumferential outer periphery, a second circumferential outer periphery radially inward of the first circumferential outer periphery and axially displaced therefrom, and a generally radially-extending face between said first and second outer peripheries; wherein said apply piston is formed with a first annular groove in said first outer periphery and a second annular groove in said second outer periphery; a first annular seal seatable within said first annular groove for sealing engagement with the transmission case; a second annular seal seatable within said second annular groove for sealing engagement with the transmission case; wherein said first and second circumferential outer peripheries and said generally radially-extending face are adapted for cooperation with the transmission case to form a selectively expandable fluid-filled chamber configured for directing fluid force to said piston for engagement of the torque-transmitting mechanism when said chamber expands; wherein said first and second annular seals are in sliding contact with said transmission case as said chamber expands; and wherein said apply piston is characterized by an absence of any additional seals seated therein and by an absence of any additional surfaces in contact with the transmission case or with any other stationary component as the chamber expands.