A piston ring with improved wear properties has a running surface, an upper ring flank, a lower ring flank, and an inner surface. The piston ring has a radius R, and wherein in a radial section, a running surface contour includes an upper region, a central region, and a lower region. The upper region of the running surface contour has a curvature radius R.sub.o, which lies between the ring radius R and infinity. The central region of the running surface contour has a curvature radius R.sub.m, which lies between the ring radius R and infinity. The lower region has a curvature radius R.sub.u, which is smaller than the ring radius R.

A piston ring with improved wear properties has a running surface, an upper ring flank, a lower ring flank, and an inner surface. The piston ring has a radius R, and wherein in a radial section, a running surface contour includes an upper region, a central region, and a lower region. The upper region of the running surface contour has a curvature radius R.sub.o, which lies between the ring radius R and infinity. The central region of the running surface contour has a curvature radius R.sub.m, which lies between the ring radius R and infinity. The lower region has a curvature radius R.sub.u, which is smaller than the ring radius R.

A three-part oil scraper ring includes an expander spring and two scraper rings, comprising a ring body (4) having an upper flank (6), a lower flank (8), a ring inner surface (10) and a ring outer surface (12) which has a ring outer contour (14) in cross-section in axial direction (A). The ring body (4) has a height H which corresponds to the greatest distance of the upper flank (6) to the lower flank (8). The ring outer contour (14) forms a running surface (16) which has a radius of curvature R which is smaller than the height H of the scraper ring (2) by a factor between 1.5 to 6, preferably between 3 to 5 and further preferably between 3.5 to 4.5.

A three-part oil scraper ring includes an expander spring and two scraper rings, comprising a ring body (4) having an upper flank (6), a lower flank (8), a ring inner surface (10) and a ring outer surface (12) which has a ring outer contour (14) in cross-section in axial direction (A). The ring body (4) has a height H which corresponds to the greatest distance of the upper flank (6) to the lower flank (8). The ring outer contour (14) forms a running surface (16) which has a radius of curvature R which is smaller than the height H of the scraper ring (2) by a factor between 1.5 to 6, preferably between 3 to 5 and further preferably between 3.5 to 4.5.

A seal ring and a sealing structure that reduce the deviation of the central axis of the seal ring from the central axis of a shaft thereby preventing the seal ring from abutting against the tip end of a housing in the operation of inserting the shaft in the housing. The seal ring includes a thin part 100A provided in a range less than 180° with respect to a circumferential direction and a thick part 100B, which is configured to protrude inward in the radial direction from an inner peripheral surface of the thin part 100A, the thin part 100A has an abutment joint part 110, and the thick part 100B has, at respective ends of both side surfaces on an inner peripheral surface side thereof, a concave part 120 over an entire range thereof to form a gap between the ends of the both side surfaces and corner parts at both ends of a groove bottom of the annular groove.

A steel piston (1) for a combustion engine, having an upper part in which a ring section (7) with at least one ring groove (8) is arranged, wherein the upper part is adjoined by a lower part that has two opposing skirt wall sections (2), wherein the two skirt wall sections (2) are connected via two mutually opposite case walls (3), wherein a pin bore (4) surrounded by a piston boss (6) is provided in each case wall (3). In one example, there is at least one aperture (14) or at least one recess in the case wall (3) in the region between the piston boss (6) and the skirt wall section (2).

A steel piston (1) for a combustion engine, having an upper part in which a ring section (7) with at least one ring groove (8) is arranged, wherein the upper part is adjoined by a lower part that has two opposing skirt wall sections (2), wherein the two skirt wall sections (2) are connected via two mutually opposite case walls (3), wherein a pin bore (4) surrounded by a piston boss (6) is provided in each case wall (3). In one example, there is at least one aperture (14) or at least one recess in the case wall (3) in the region between the piston boss (6) and the skirt wall section (2).

An oil scraper ring is provided for pistons (2) of an internal combustion engine having an oil scraper piston ring groove (4) formed without at least one oil drain bore. The scraper ring includes a ring body (6) comprising an upper ring flank (8), a lower ring flank (10), a ring inner side (12), a ring outer side (14) and two abutting surfaces (16, 18). An upper oil scraper rail (20) and a lower oil scraper rail (22) extend in the circumferential direction in spaced apart relation from one another in the axial direction and extend radially to the outside from the ring outer side (14) are arranged on the ring outer side (14). Oil passages (24) running in the radial direction are arranged in a region between the upper scraper rail (20) and the lower scraper rail (22), and at least one groove (26) extends in the radial direction on the lower ring flank (10).

An oil wiper packing for a piston rod of a crosshead piston compressor, and corresponding assembly method. The oil wiper packing has at least one chamber disc having a chamber disc cutout, wherein a wiper ring arranged in the chamber disc cutout. At least two chamber discs, each having a chamber disc cutout, are arranged in succession in a direction of extent (L), and a single wiper ring is in each chamber disc cutout. Each wiper ring has no play or only negligible play in the direction of extent (L) in the operating state but is movable in the radial direction. It is necessary to set the play in in the cold state during the assembly of the wiper rings. Such an arrangement allows advantageous wiping of oil, preventing oil from spreading in the direction of extent of the piston rod.

An oil wiper packing for a piston rod of a crosshead piston compressor, and corresponding assembly method. The oil wiper packing has at least one chamber disc having a chamber disc cutout, wherein a wiper ring arranged in the chamber disc cutout. At least two chamber discs, each having a chamber disc cutout, are arranged in succession in a direction of extent (L), and a single wiper ring is in each chamber disc cutout. Each wiper ring has no play or only negligible play in the direction of extent (L) in the operating state but is movable in the radial direction. It is necessary to set the play in in the cold state during the assembly of the wiper rings. Such an arrangement allows advantageous wiping of oil, preventing oil from spreading in the direction of extent of the piston rod.