The present invention addresses the problem of providing a piston ring covered with a DLC coating that has excellent wear resistance and shows a low attacking property on a cylinder bore sliding surface. The problem is solved by a piston ring which is used in the presence of an engine lubricating oil and includes a DLC coating on an outer peripheral sliding surface. The DLC coating has an sp.sup.2 component ratio of 0.5 to 0.85 as determined from a TEM-EELS spectrum obtained by a combination of a transmission electron microscope (TEM) and electron energy loss spectroscopy (EELS), as well as a coating hardness of 12 GPa to 26 GPa and a Young's modulus of 250 GPa or less as measured by a nanoindentation method.

A sliding member includes: a base; a chromium-based hard chromium plated layer formed on the surface of the base; a hard carbon layer that is mainly composed of carbon element and is formed on the hard chromium plated layer. The hydrogen concentration of the hard chromium plated layer is equal to or less than 150 mass ppm. A method for producing the sliding member involves heating the surface of the base on which the chromium-based hard chromium plated layer has been formed at a temperature of 250° C. or more so that the hydrogen concentration of the hard chromium plated layer is equal to or less than 150 mass ppm, and thereafter forming the hard carbon layer mainly composed of carbon element on the hard chromium plated layer.

A sliding member includes: a base; a chromium-based hard chromium plated layer formed on the surface of the base; a hard carbon layer that is mainly composed of carbon element and is formed on the hard chromium plated layer. The hydrogen concentration of the hard chromium plated layer is equal to or less than 150 mass ppm. A method for producing the sliding member involves heating the surface of the base on which the chromium-based hard chromium plated layer has been formed at a temperature of 250° C. or more so that the hydrogen concentration of the hard chromium plated layer is equal to or less than 150 mass ppm, and thereafter forming the hard carbon layer mainly composed of carbon element on the hard chromium plated layer.

The present disclosure provides a sealing ring assembly having a sealing ring and a reinforcement, configured to seal a high-pressure region from a lower pressure region of a piston and cylinder device. The sealing ring may be segmented, and a metal layer, wire, or other reinforcement may be affixed to the ring. The reinforcement is placed into tension against the sealing ring, which is correspondingly placed into compression. The composite structure of a relatively brittle sealing ring and reinforcement provides for reduced tensile loads in the sealing ring, thus extending life and reducing the likelihood of failure. The brittle portion of the sealing ring assembly may include a polymer or ceramic such as graphite, which is relatively less strong in tension than compression.

The present disclosure provides a sealing ring assembly having a sealing ring and a reinforcement, configured to seal a high-pressure region from a lower pressure region of a piston and cylinder device. The sealing ring may be segmented, and a metal layer, wire, or other reinforcement may be affixed to the ring. The reinforcement is placed into tension against the sealing ring, which is correspondingly placed into compression. The composite structure of a relatively brittle sealing ring and reinforcement provides for reduced tensile loads in the sealing ring, thus extending life and reducing the likelihood of failure. The brittle portion of the sealing ring assembly may include a polymer or ceramic such as graphite, which is relatively less strong in tension than compression.

The piston ring unit includes a plurality of piston rings and an inner contact ring. A plurality of piston rings are disposed adjacent to each other in an axial direction of the piston such that joints of plurality of the piston rings do not overlap with each other in the axial direction. An inner contact ring is interposed between an outer circumferential surface of the piston and an inner circumferential surface of the piston ring in a state where the inner contact ring extends over all of the plurality of piston rings in the axial direction, and is disposed such that an opening of the inner contact ring does not overlap with the joint of the at least one piston ring as viewed in a radial direction of the piston.

A resin composition including polytetrafluoroethylene (A); graphite (B); talc (C); and an abrasion resistance-improving filler (D), the resin composition containing 50 to 80 parts by mass of the polytetrafluoroethylene (A), 1 to 35 parts by mass of the graphite (B), 1 to 35 parts by mass of the talc (C), 16 to 40 parts by mass of a total of the graphite (B) and the talc (C), and 2 to 10 parts by mass of the abrasion resistance-improving filler (D) relative to 100 parts by mass of a total of the polytetrafluoroethylene (A), the graphite (B), the talc (C), and the abrasion resistance-improving filler (D). Also disclosed is a molded article obtained by compression molding, extrusion molding, or injection molding the resin composition.

A piston ring includes a first ring portion which is fitted onto an outer circumferential portion of a piston and which is capable of sliding relative to an inner wall surface of a cylinder, and a second ring portion which is fitted onto the outer circumferential portion of the piston, arranged side-by-side with the first ring portion in the axial direction, and which is capable of sliding relative to the inner wall surface of the cylinder. The second ring portion is fitted onto the outer circumferential portion of the piston in such a way as to be positioned on a side opposite to a compression chamber inside the cylinder, relative to the first ring portion, and has a greater hardness than the first ring portion has.

The invention relates to a hydraulic tool mount having a bore into which a sealing piston is inserted, wherein the sealing piston comprises a pin, a seal and a head which are arranged one behind the other in an axial direction (A) and thus form a stack, wherein the seal comprises a circumferential sealing lip for abutment and sealing against an inner wall of the bore in order to achieve a first sealing effect, and the bore comprises a sealing seat which, when the sealing piston is inserted, forms a stop for the head in axial direction (A), so that, in an end position of the sealing piston, the head abuts the sealing seat and thereby closes the bore in order to achieve a second sealing effect. The invention further relates to a corresponding sealing piston.

An internal combustion engine includes an engine block, a piston, a cylinder head, and a valve train. The engine block includes a cylinder block including a cylinder bore and a crankcase defining a crankcase chamber with a crankshaft positioned within the crankcase chamber. The piston is coupled to the crankshaft and configured to reciprocate within the cylinder bore. The cylinder head is coupled to the cylinder block. The valve train includes a camshaft, a first and second pushrod, a first and second rocker arm, an exhaust valve housed, and an intake valve. The first rocker arm, the second rocker arm, the exhaust valve, and the intake valve each include at least a layer of a low friction material. The first and second pushrod each pass through a pushrod seal to prevent fluid from reaching the rocker chamber to fluidly isolate the rocker chamber from the crankcase chamber.