Provided is a sliding member having a hard carbon coating that makes high wear resistance compatible with a low coefficient of friction and that has excellent peeling resistance. A sliding member (100) includes a base member (10) and a hard carbon coating (12) formed on the base member (10). The indentation hardness of the hard carbon coating (12) decreases gradually from the base member side to the surface side. The hard carbon coating (12) has an indentation hardness distribution at 0T/Ttotal0.6 approximated by a first line and an indentation hardness distribution at 0.9T/Ttotal1 approximated by a second line, and the intersection between the first line and the second line (T2/Ttotal, H2) satisfies Expression (1), (H3H1)T2/Ttotal+H1<H20.9H1, and Expression (2), 0.6T2/Ttotal0.9.

A piston ring is formed from a steel substrate consisting of the carbon in a range of 0.80-0.95 wt. %, silicon in a range of 0.30-0.55 wt. %, manganese in a range of 0.25-0.5 wt. %, phosphorus in a range of up to 0.04 wt. %, sulfur in a range of up to 0.04 wt. %, chromium in a range of 17-18 wt. %, molybdenum in a range of 0.70-1.25 wt. %, vanadium in a range of 0.05-0.15%, the remainder iron. The ring has been through hardened and tempered so that it has a hardness of 46-54 HRC. A coating is then applied via PVD or other suitable methods onto the ring surface to create the finished piston ring.

To provide a combined oil control ring comprising a pair of upper and lower side rails and an axially corrugated spacer expander having upper and lower portions for automobile engines, which is capable of keeping an excellent oil-controlling function without sticking between a spacer expander and side rails even in a long period of engine operation, the upper and lower portions of the spacer expander have tabs pushing inner peripheral surfaces of the side rails, projections supporting the side rails, and intermediate portions between the tabs and the projections; each intermediate portion opposing the side rail has at least one groove extending in a substantially circumferential direction is recessed when viewed along a radial direction.

A supporting arrangement for an eccentric member (8) of an adjusting arrangement (6) of a connecting rod (2) of a reciprocating piston internal combustion engine having at least one piston rod (18) that is guided displaceably by a piston (20) and a seal member (24) is connected to the supporting piston (20) in a supporting cylinder (12, 14) which is provided in the connecting rod (2) and has a longitudinal axis (16). The supporting piston (20) enclosing at least one cylinder chamber (22) with the supporting cylinder (12, 14). A side (28) of the the supporting piston (20) that is directed toward the cylinder chamber (22) has a brake piston (30) that can be moved in the longitudinal axis (16). The brake piston (30) is mounted on the supporting piston (20) and can be prestressed by a spring (32).

An oil ring wire (2) containing an alloy steel as a material. The alloy steel contains: 0.50 to 0.65% by mass C; 1.60 to 2.30% by mass Si; 0.60 to 1.10% by mass Mn; 0.75 to 1.15% by mass Cr; 0.18 to 0.45% by mass Ni; 0.05 to 0.15% by mass V; and 0.15% by mass or less Cu. In the oil ring wire 2, an area percentage of a carbide is 1.00% or less. Also disclosed is a method of producing the oil ring wire.

To provide a long-life compression ring without an increase in the outer peripheral abrasion near the gap regardless of the ring material or the presence or absence of the outer peripheral hard coating, in an annular compression ring having a pair of gap faces opposed to each other to form a free gap and a nominal diameter d1 equal to an inner diameter of a cylinder to which the compression ring is attached to along with a piston, a self tangential force is 5N to 50N, and a radius of curvature R1 and the nominal diameter d1 satisfy a relationship:
?0.01?(2R1?d1)/d1<0.002
where the radius of curvature R1 is that of outer peripheral arcs of gap end portions in a free shape state before the compression ring is attached to the cylinder, and the gap end portions are defined in ranges between the gap faces and positions where a center angle from a midpoint of the free gap is 35?.

A piston ring, and in particular a compression piston ring, has a running face, upper and lower flank regions, an inner circumferential surface and a joint, wherein at least the running face is provided with at least one wear-resistant PVD or CVD layer, wherein the PVD or CVD layer extends at a predefinable layer thickness across a circumferential length of more than 95%, but less than 100% of the piston ring, and defined circumferential sections are designed in a layer-free manner in the region of the joint.

A piston ring, and in particular a compression piston ring, has a running face, upper and lower flank regions, an inner circumferential surface and a joint, wherein at least the running face is provided with at least one wear-resistant PVD or CVD layer, wherein the PVD or CVD layer extends at a predefinable layer thickness across a circumferential length of more than 95%, but less than 100% of the piston ring, and defined circumferential sections are designed in a layer-free manner in the region of the joint.

To provide a piston ring free from microwelding to a piston while exhibiting excellent wear resistance in side surfaces, for a long period of use in a high-temperature, high-pressure environment, and its production method, a nitride layer is formed on at least one of upper and lower side surfaces of the piston ring, and then subjected to a phosphate chemical conversion treatment, such that the nitride layer has at least one of granular and vermicular surface forms.

To provide a piston ring free from microwelding to a piston while exhibiting excellent wear resistance in side surfaces, for a long period of use in a high-temperature, high-pressure environment, and its production method, a nitride layer is formed on at least one of upper and lower side surfaces of the piston ring, and then subjected to a phosphate chemical conversion treatment, such that the nitride layer has at least one of granular and vermicular surface forms.