Abstract: A method for the machine-milling of intake and/or exhaust ducts formed in a cylinder head includes working off the inner wall surfaces of the intake and/or exhaust ducts at least in part, preferably completely, with a multi-axis, preferably five-axis, CNC-controlled cherry head in a stabbing movement. Grooves are thus formed in the inner wall surfaces that extend primarily in the flow direction of the ducts.

Abstract: A piston ring with an upper part ring having an upper ring surface and with a lower part ring having a lower ring surface, and with a ring spring which is arranged between the part rings and acts with spring force upon these radially outward, characterized in that each of the two part rings has, on its circular-ring surface in each case facing the other part ring, a plurality of elevations arranged so as to be separated from one another by depression regions, with plateau surfaces which are parallel to the ring surfaces and are flat-planar or descend and which have in each case, the ring axis of the respective part ring, toward an inner-flank indentation which emanates, oriented parallel to the ring axis, from the plateau surfaces and runs out toward said spring axis, in each case parallel to the upper and the lower ring surface, and which has a quarter-circle-shaped cross section, the radius rv of said inner-flank indentation being 1 to 10% larger than the outer radius of the circle cross section of the comm

Abstract: A piston includes a piston head, two skirt walls disposed opposite one another and at least one pin bearing disposed between the skirt walls and supported on the piston head. Each skirt wall extends over a partial region of the periphery of the piston or piston head. The two skirt walls are connected by at least one self-supporting support wall disposed at a distance from the piston head. A cylinder and piston assembly and a piston ring for a cylinder, are also provided.

Abstract: A process for inserting a piston pin locking ring, particular slotted snap ring, into a locking groove of a pin bore of a piston. The piston pin locking ring is radially pre-tightened and reduced in size in a first step in such a manner that its outside diameter becomes smaller than the inner diameter of the pin bore. The piston pin locking ring is subsequently introduced in the pre-tightened state into the pin bore without contact and without contacting the inner wall of the pin bore and is brought in position inside the pin bore in the area of the locking groove. Then the piston pin locking ring is freed by a relaxing and loosening of the tightening force and by springing into the locking groove and is thus fixed in place.