A ringset is configured to be arranged on a piston for sealing a gas in a high-pressure region of a cylinder in the absence of oil or other liquid lubricant. The ringset includes one or more rings made from a high-strength material as a sealing element. The ringset also includes a solid lubricant applicator configured to provide lubrication between the one or more rings and a bore of the cylinder. For example, the ring can support pressure loads from high-pressure gas without breaking, while the applicator need not act as a seal. As the piston reciprocates in the bore, the applicator slides against the bore and applies solid lubricant material to the bore, resulting in a solid lubricant film on the bore against which the sealing element may slide. The applicator includes a material such as a graphite, a polymer, or other suitable solid lubricant.

A piston of a cylinder of an internal combustion engine includes: a piston skirt; a grooved ring belt on a first axial side of the piston skirt, the ring belt grooves being limited by, and separated from one another by, ring lands, the ring grooves for receiving a piston ring; and an oil collection channel between the piston skirt and the ring belt. The oil collection channel has a greater depth than in the circumferential position of a coupling side of the piston and/or in the circumferential position of a coupling opposite side of the piston. The oil collection channel has a gradient, the gradient emanating from an axial depth in a region of the coupling side and/or of the coupling opposite side in the direction of the axial depth in the region of the pressure side and/or of the pressure opposite side.

A piston of a cylinder of an internal combustion engine includes: a piston skirt; a grooved ring belt on a first axial side of the piston skirt, the ring belt grooves being limited by, and separated from one another by, ring lands, the ring grooves for receiving a piston ring; and an oil collection channel between the piston skirt and the ring belt. The oil collection channel has a greater depth than in the circumferential position of a coupling side of the piston and/or in the circumferential position of a coupling opposite side of the piston. The oil collection channel has a gradient, the gradient emanating from an axial depth in a region of the coupling side and/or of the coupling opposite side in the direction of the axial depth in the region of the pressure side and/or of the pressure opposite side.

A housing of an axial piston device is provided with a drain port for discharging the retained oil to the outside and a supply oil passage for guiding lubricating oil, which has been supplied from an oil source, toward a first hydraulic axial piston member. The drain port is arranged so as to bring about such a retained-oil level that a second hydraulic axial piston member, which is disposed below the first hydraulic axial piston member, is partially or entirely immersed in the retained oil while the first hydraulic axial piston member is not immersed in the retained oil.

A housing of an axial piston device is provided with a drain port for discharging the retained oil to the outside and a supply oil passage for guiding lubricating oil, which has been supplied from an oil source, toward a first hydraulic axial piston member. The drain port is arranged so as to bring about such a retained-oil level that a second hydraulic axial piston member, which is disposed below the first hydraulic axial piston member, is partially or entirely immersed in the retained oil while the first hydraulic axial piston member is not immersed in the retained oil.

A wind turbine includes a nacelle with a main bearing tilted with its rotation axis towards the horizontal axis and including an inner and outer ring, wherein the main bearing is a slide bearing and the inner ring is stationary while the outer ring rotates, with the main bearing being lubricated, and with the outer ring including a first and a second sealing means, wherein the first sealing means is due to the tilt of the main bearing lower than the second sealing means, wherein a stationary leakage lubrication fluid collection means is provided adapted for collecting lubrication fluid, wherein the outer ring is provided with one or more axial bores connecting a leakage lubrication fluid collection area to the leakage lubrication fluid collection means and wherein each sealing means includes a groove accommodating a sealing element and a sealing element carrier ring.

A piston for an internal combustion engine may include a ring belt, a groove, and an additional groove. The ring belt may extend along an axial direction. The groove may be arranged on the outer circumference of the ring belt and may be configured to receive an oil scraper ring. The additional groove may be arranged on the outer circumference spaced apart from the groove with respect to the axial direction. The additional groove may include a first groove side axially facing away from the groove and a second groove side axially facing the groove. The first groove side may include an axial step.

In a piston including a plurality of piston rings, a state where a difference in differential pressure between the piston rings is eased is maintained even after passage of time, and the life of the piston rings is extended. A piston includes a piston body in which a plurality of ring grooves is formed, and a plurality of piston rings respectively arranged in the ring grooves. In the piston, a leakage groove is formed on a low-pressure side surface of the ring groove, and in a state where the piston ring is abutted with the low-pressure side surface while being abutted with a cylinder, the leakage groove ensures communication between a high-pressure side space and a low-pressure side space with respect to the piston ring.

In a piston including a plurality of piston rings, a state where a difference in differential pressure between the piston rings is eased is maintained even after passage of time, and the life of the piston rings is extended. A piston includes a piston body in which a plurality of ring grooves is formed, and a plurality of piston rings respectively arranged in the ring grooves. In the piston, a leakage groove is formed on a low-pressure side surface of the ring groove, and in a state where the piston ring is abutted with the low-pressure side surface while being abutted with a cylinder, the leakage groove ensures communication between a high-pressure side space and a low-pressure side space with respect to the piston ring.

A hermetic compressor includes a closed vessel for storing lubricating oil, an electric-driving element, and a compressing element driven by the electric-driving element. The compressing element includes a cylinder block forming a compression chamber, a piton that reciprocates inside the compression chamber, and an oiling device for supplying the lubricating oil to an outer circumference of the piston. A first oil groove is concavely formed on the outer circumference of the piston, and a second oil groove is concavely formed on a side opposite to the compression chamber relative to the first oil groove. The second oil groove has a spatial volume same or greater than that of the first oil groove. An expanded clearance portion is provided such that a clearance between the piston and the cylindrical hole portion broadens from a top dead point to a bottom dead point.