Abstract: 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.

Abstract: A three-piece oil control ring is provided for use in a piston groove of an internal combustion engine. The ring comprises a first annular segment and a second annular segment, associated to an expanding element. The expander has a substantially annular shape and comprises a first end facing the internal wall of the groove when the ring is mounted on the piston and a second opposite end. The ring further comprises an intermediate portion having at least one protrusion for association with the segments. Still further, the first end exhibits first thickness value (E1), the second end exhibits second thickness value (E2) and the substantially intermediate portion exhibits third thickness value (E3), wherein the value of (E1) is substantially lower than the value of (E3) and lower or similar to the value of (E2), the difference between (E1) and (E3) being substantially higher than that between (E1) and (E2).

Abstract: A segmented piston ring assembly includes piston ring segments 2 having stepped ends 5, 6, at least one piston ring segment 2 including a radial step on a radially inner peripheral surface 9 over a part of the width of the piston ring segment 2, and a single-cut sealing ring 3, which bears radially against the inside of the peripheral surface 9 of the piston ring segments 2, the sealing ring 3 including an axial recess 10, 12 which cooperates with the radial step 4 of the piston ring segment 2 to prevent relative rotation therebetween.