A piston in a liquid-pressure rotating device in which pistons are arranged at a cylinder block rotatable together with a rotating shaft, includes: a cylindrical peripheral wall main body portion including a hollow portion, an opening portion formed at one end of the body portion and communicating with the hollow portion; a lid portion welded to an inner peripheral surface of the opening portion sealing the hollow portion and including an outer surface formed as a pressure receiving surface which receives liquid pressure; and a stress reducing portion provided on an inner peripheral surface of the body portion, the inner peripheral surface in contact with or close to an end portion of a welded portion formed between the opening portion and the lid portion, the end portion located at the hollow portion side, the stress reducing portion configured to reduce stress acting on the end portion of the welded portion.

A piston assembly and method of construction thereof for an internal combustion engine are provided. The assembly includes a piston head having an upper combustion wall with an undercrown surface and a ring belt region. The piston head has a floor with an upper surface and a bottom surface. The floor is spaced beneath the upper combustion wall in radial alignment with the ring belt region. A substantially enclosed, annular cooling gallery is bounded by the undercrown surface and the floor. A pair of pin bores depends directly from the floor of the cooling gallery. The assembly further includes a pin having ends configured for oscillating receipt in the pin bores. A pin bearing surface extends within the pin bores and between the pin bores in the lower surface of the floor. The assembly includes a connecting rod with an end fixed to the pin for conjoint oscillation therewith.

Piston blank for a piston, comprising a piston lower part, which comprises a first joining surface running around a central axis of the piston blank, and a piston upper part, which comprises a second joining surface running around the central axis and an inner surface running around the central axis and adjoining the second joining surface as viewed along the central axis, wherein the piston upper part can be placed with its second joining surface on the first joining surface, and wherein a tangential plane which is assigned to the second joining surface is inclined relative to the central axis such that the tangential plane intersects the inner surface.

A piston assembly may include a piston rod and a piston disposed on the piston rod. The piston may include a frame end cap defining a through-bore for receiving the piston rod, and the frame end cap may form a first end of the piston. The piston may include an outer end cap defining a through-bore for receiving the piston rod, and the outer end cap may form a second end of the piston. The piston may also include a center support defining a through-bore for receiving the piston rod. The center support may be disposed between the frame end cap and the outer end cap, and an outer surface of the piston rod and an inner circumferential surface of the center support may define a radial gap.

A method for producing a piston may include forming a piston blank in a first forming tool such that the piston blank surrounds a ring carrier configured to receive a piston ring via positive engagement after producing the ring carrier by a sintering process. The piston blank, at least in a circumferential region disposed at a piston head, may be composed of a light metal alloy suitable for forging. The method may also include removing the piston blank from the first forming tool and placing the piston blank in a second forming tool, and inserting a holding-down tool into the second forming tool to hold the ring carrier down. The method may further include pressing a final forming punch into the second forming tool to deform the piston blank and form a piston.

A piston assembly and method of construction thereof for an internal combustion engine are provided. The assembly includes a piston head having an upper combustion wall with an undercrown surface and a ring belt region. The piston head has a floor with an upper surface and a bottom surface. The floor is spaced beneath the upper combustion wall in radial alignment with the ring belt region. A substantially enclosed, annular cooling gallery is bounded by the undercrown surface and the floor. A pair of pin bores depends directly from the floor of the cooling gallery. The assembly further includes a pin having ends configured for oscillating receipt in the pin bores. A pin bearing surface extends within the pin bores and between the pin bores in the lower surface of the floor. The assembly includes a connecting rod with an end fixed to the pin for conjoint oscillation therewith.

The present disclosure describes composite actuator piston rods and methods for making such rods. Composite actuator piston rods of the present disclosure may include a composite actuator rod tube having a flared end, an insert, wherein the insert has a complementary shape to the flared end, a piston head concentrically surrounding the flared end of the composite actuator rod tube, and a piston head nut configured to threadingly attach to the piston head.

Provided are a disc brake and a piston whose weights can be effectively reduced. A disc brake includes a piston configured to press a pad against a disc. The piston includes a body member formed into a bottomed cylindrical shape and including a cylinder portion and a bottom portion. The cylinder portion and the bottom portion are approximately equal in wall thickness. The piston further includes a plate-shaped member fixed to an external bottom surface of the body member and disposed within a range of the external bottom surface and in a region including a center of the external bottom surface.

A piston for an internal combustion engine may include a piston head and a piston skirt. The piston skirt may include a plurality of box walls and a plurality of skirt walls. The plurality of box walls may be arranged opposite one another and may include a plurality of boss bores. The plurality of skirt walls may be arranged opposite one another and may have running surfaces. The piston may also include a cover element that may include a substantially circular cover plate and an aperture. The aperture may be disposed on the cover plate and may be configured for the passage of a connecting rod. The cover element may be secured to a lower region of the piston skirt. The cover plate may close a piston cross-sectional area.

A linear reciprocating engine may include an engine block, a cylinder having combustion chambers at opposing ends, cylinder heads located at an end of the respective combustion chambers, respectively, and a double-faced piston. The engine may further include piston rod portions extending from both faces of the piston through the combustion chambers. The engine may further include an exhaust outlet in a peripheral cylinder wall and elongated channels in the piston rod portions being configured to serve as an intake inlet for gas from a location external to the cylinder. When the piston is in a combustion stage in a first combustion chamber, the piston blocks the exhaust outlet from communicating with the first chamber with the first channel access opening outside the first chamber, while simultaneously the exhaust outlet is in communication with a second combustion chamber with the second channel access opening within the second chamber.