Abstract: A sealing device that hermetically seals a gap between a first member and a second member that is reciprocally movable with respect to the first member. The sealing device seals liquid supplied into a pressurizing chamber surrounded by the first member and the second member. The sealing device includes a seal member that is attached to the second member. The seal member slides relative to the first member while being in contact with the first member. The seal member includes a base portion and a protruding portion. The protruding portion protrudes from the base portion toward the first member to separate the first member from the base portion. After the liquid is supplied into the pressurizing chamber to fill the pressurizing chamber with the liquid, the protruding portion elastically deforms to bring the base portion into close contact with the first member.

Abstract: A piston for an automatic transmission, including a first piston member forming a cylindrical portion and a second piston member forming a bottom portion, wherein the first piston member has a plurality of engaging grooves formed in one of opposite axial end portions thereof, each of the engaging grooves having a radial surface extending in a radial direction of the first piston member, and the second piston member has a plurality of elongate claws (70) extending in a circumferential direction thereof and respectively corresponding to the engaging grooves, each elongate claw having a free end portion and a fixed end portion, and being bent in an axial direction of the second piston member such that the free end portion is spaced from the fixed end portion in the axial direction toward an open end of the piston, each elongate claw having a first engaging lug which is formed at the free end portion and which is held in engagement with the corresponding engaging groove and in pressing contact with the radial end

Abstract: A piston for an automatic transmission, including a first piston member forming a cylindrical portion and a second piston member forming a bottom portion, wherein the first piston member has a plurality of engaging grooves formed in one of opposite axial end portions thereof, each of the engaging grooves having a radial surface extending in a radial direction of the first piston member, and the second piston member has a plurality of elongate claws (70) extending in a circumferential direction thereof and respectively corresponding to the engaging grooves, each elongate claw having a free end portion and a fixed end portion, and being bent in an axial direction of the second piston member such that the free end portion is spaced from the fixed end portion in the axial direction toward an open end of the piston, each elongate claw having a first engaging lug which is formed at the free end portion and which is held in engagement with the corresponding engaging groove and in pressing contact with the radial end