A scraper ring for a piston includes a top surface, a bottom surface, an inner surface, and an outer surface. The top surface has a first planar portion and a first angled portion. The bottom surface has a second planar portion and a second angled portion. The second angled portion is configured to slidably contact the first angled portion to adjust a diameter of the scraper ring. The inner surface connects the top surface to the bottom surface. The outer surface is opposite to the top surface and is configured to form 360 degrees of contact with a wall of a cylinder to substantially limit an amount of oil entering a combustion chamber of the cylinder.

A piston ring with a coated outer surface is provided. The coating is disposed on end sections of the outer surface adjacent a gap. Typically, a middle section of the outer surface located between the end sections is not coated. The coating can be formed of CrN or DLC, and the CrN coating can be applied by physical vapor deposition (PVD). The end sections of the outer surface, upon which the coating is applied, are rough. For example, the outer surface can be blasted or otherwise textured to achieve the rough surface. The rough surface retains oil and distributes stress better than a smooth surface, and thus reduces crazing and flaking of the coating.

The invention relates to an internally clamping rectangular seal (40) for sealing a shaft (20) with respect to a housing (10), wherein the rectangular seal can be inserted into a groove (13) disposed circumferentially on a shaft bore (12), wherein the rectangular seal is interrupted along its circumferential direction at a joint (42) and two ring-end sections (43, 44) are formed, and wherein the rectangular seal has an outer surface (40.4) facing radially outwards, an inner clamping surface (40.1) facing radially inwards and opposing flank surfaces (40.3) facing in the axial direction. Therefore, provision is made that at least one contact ramp (45.1, 45.2, 45.3) is disposed at at least one ring-end section, that the at least one contact ramp is oriented obliquely with respect to the circumferential direction and obliquely with respect to the radial direction of the rectangular seal, and that the at least one contact ramp, starting from a non-stressed state of the rectangular seal, forms a first mechanical contact, pointing in the circumferential direction, between the opposing ring-end sections when the radius of the rectangular seal is reduced by prestressing the rectangular seal.

The rectangular seal permits low leakage rates and can be installed non-directionally.

A piston ring set of a cryogenic pump includes a first piston ring and a second piston ring which are dissimilarly shaped and cooperatively shaped to form a hollow cylindrical shape when in abutment to one another. The first piston ring is C-shaped and defines a middle portion disposed between a first end portion and a second end portion. A piston ring gap is disposed between a first distal end of the first end portion and a second distal end of the second end portion. When the first piston ring is in abutment with the second piston ring forming the hollow cylindrical shape, the second piston ring does not extend along the middle portion of the first piston ring while the second piston ring does extend along the first end portion and second end portion of the first piston ring.

A seal assembly includes a tensionable annular member and a gap seal annular member that are axially juxtaposed and configured to be carried by one of a pair of coaxially movable components for sealingly engaging another one of the pair of components. The tensionable annular member includes first and second radial surfaces, an inner surface, and an outer contact surface. Rounded bottom grooves are formed across the first radial surface from the outer contact surface to the inner surface. In another embodiment, notches are formed across the inner surface from the first radial surface to the second radial surface.

A stepped piston ring (2) includes a ring outer side (5), an upper ring flank (6), and a lower ring flank (8). The ring outer side (5) on the upper edge has a notch (10, so that only a lower portion of the ring outer side (5) forms a contact surface (4).

A stepped piston ring (2) includes a ring outer side (5), an upper ring flank (6), and a lower ring flank (8). The ring outer side (5) on the upper edge has a notch (10, so that only a lower portion of the ring outer side (5) forms a contact surface (4).

Embodiments of a combination piston and piston ring to reduce the volume of a crevice defined between the circumferential wall of a cylinder and a portion of the outer wall of a piston within the cylinder, the portion extending down from the top of the piston. The combination piston and piston ring is configured such that pressurized fluid within the cylinder reliably urges a radial face of the piston ring to sealingly engage the circumferential wall of the cylinder, even as the piston reciprocates within the cylinder.

Embodiments of a combination piston and piston ring to reduce the volume of a crevice defined between the circumferential wall of a cylinder and a portion of the outer wall of a piston within the cylinder, the portion extending down from the top of the piston. The combination piston and piston ring is configured such that pressurized fluid within the cylinder reliably urges a radial face of the piston ring to sealingly engage the circumferential wall of the cylinder, even as the piston reciprocates within the cylinder.

An oil scraper ring (4) includes a ring element (6), having an upper ring edge (8), a lower ring edge, a ring inner side and a ring outer side (14. The ring element (6) is provided with two opposing contact surfaces (20), between which there is a ring gap (18. The ring element (6) is provided with at least one scraper bar (24, 26) on the ring outer side (14. The oil scraper ring (4) is provided with two recesses (28), each arranged on each contact surface (20), and each adjoining at least on the ring outer side (14), the respective contact surface (20) and the upper ring edge (8).