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.

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 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).

A multi-piece oil scraper piston ring includes a slotted spring element and at least one lamella element which is operatively connected to the slotted spring element and provided with a joint, the spring element being designed as a meander spring that axially receives and radially supports the lamella element, the two end regions of the meander spring being provided with legs that extend approximately parallel to one another and the axial length of which is designed such that the legs at least partially engage in the joint of the lamella element.

A piston ring configured to be disposed in a floating piston for use in a vessel of a thermal energy storage system to separate a hot working fluid from a cold working fluid, wherein the piston ring comprises of a plurality of arc segments, each arc segment interconnected by a joint.

A piston ring configured to be disposed in a floating piston for use in a vessel of a thermal energy storage system to separate a hot working fluid from a cold working fluid, wherein the piston ring comprises of a plurality of arc segments, each arc segment interconnected by a joint.

A shaft mounting assembly includes an elongate shaft with an outer surface having a substantially circular cross-section and a cylinder having an inner surface defining a bore housing the shaft. A spring having a substantially circular discontinuous band with correspondingly shaped axially arcuate inner and outer surfaces. One of the surfaces comprises a groove, and the spring is positioned in the groove with both axial edges of the band located therein. In a de-energised state of the spring, the height of the band is greater than the depth of the groove, a portion of the band between the axial edges protruding out of the groove, the axial width of the band being less than the width of the groove; and, an energised state with the spring compressed within the bore to reduce the height of the band and increase the axial width compared to the de-energised state.

A fluid actuator includes housing defining a cylinder bore and first and second fluid passages. A circumferential detent groove extends into the housing from the cylinder bore. The cylinder bore receives a piston having a top face and a skirt in sliding engagement. A circumferential detent ring groove extends radially inwardly into the skirt. The detent ring groove has a first portion of a first depth and a second portion of a second, greater depth. An o-ring is at least partially received in the second portion. A wear ring is at least partially received in the first portion and overlies the o-ring. The o-ring biases the wear ring outwardly of the detent ring so that the wear ring may be selectively engaged with the detent groove.

A fluid actuator includes housing defining a cylinder bore and first and second fluid passages. A circumferential detent groove extends into the housing from the cylinder bore. The cylinder bore receives a piston having a top face and a skirt in sliding engagement. A circumferential detent ring groove extends radially inwardly into the skirt. The detent ring groove has a first portion of a first depth and a second portion of a second, greater depth. An o-ring is at least partially received in the second portion. A wear ring is at least partially received in the first portion and overlies the o-ring. The o-ring biases the wear ring outwardly of the detent ring so that the wear ring may be selectively engaged with the detent groove.

An internal combustion may include a cylinder having a first combustion chamber at one end and a second combustion chamber at an opposing end, first and second cylinder heads located at an end of the first and second combustion chambers, respectively, and a double-faced piston slidably mounted therein. The piston may be configured to move in a first stroke that includes an expansion stroke portion and a non-expansion stroke portion. The engine may further include first and second piston rod portions extending from opposite faces of the piston. A recess in the piston rod portions may be configured to communicate gases between a combustion chamber and locations outside the cylinder. There may also be a chamber surrounding the first or second piston rod portion, the chamber configured to be supplied with gas and the chamber being isolated from the first combustion chamber and the second combustion chamber.