Abstract: A piston, e.g. for an internal combustion engine, comprises a crown (16) and a skirt (12). The skirt (12) has an aperture (22) in which an insert (14) of a different material from the remainder of the skirt is secured. The insert (14) may be of plastics material injection moulded into a metal skirt. The insert (14) provides a plurality of pads (34) which extend from a thrust surface of the skirt so that the pads can transmit lateral forces and cause lubricant to be forced over the pads by hydrodynamic action during reciprocation of the piston.

Abstract: The piston comprises a crown (12), and a skirt 30 made of plastics material secured to the crown. The crown (12) is formed integrally with a depending boss (16) arranged to receive a gudgeon pin (18) by which the piston is connected to a connecting rod (24). The skirt (30) encircles the boss (16) and is spaced therefrom.

Abstract: Pistons are described comprising a crown portion and a skirt portion, the crown portion having depending from the underside thereof a boss, the boss having secured thereto at least two bearing members in fixed relationship to the piston body and which bearing members co-operate with an associated connecting rod. The bearing members may be located in rebates in the boss such that piston firing loads are born substantially in compression. The bearing members are in one embodiment secured to the boss by a bolt and nut. The bearing members may comprise ferrous, copper-based or aluminium based alloys depending upon the application environment.

Abstract: Pistons are discribed comprising a crown portion which also includes a piston ring belt and gudgeon-pin bosses and which crown portion comprises a ferrous allow and a seperate articulated skirt portion comprising a casting of aluminum alloy, steel or cast iron which also includes gudgeon-pin bores, the crown portion and the skirt portion having a common gudgeon-pin about which the articulated skirt portion is freely able to move relative to the crown portion.

Abstract: Pistons for internal combusion engines are described. The pistons comprise a crown component and a skirt component wherein the crown component consists of an iron or nickel based alloy annular portion having fitted directly therein a ceramic insert, the crown component being joined to the skirt component by an annular composite laminated member of steel and aluminium alloy the steel of the laminated member being energy beam welded to the annular portion of the crown component and the aluminum alloy of the laminated member being energy beam welded to the skirt component there being after welding a sealed, hollow, annular chamber disposed at the junction between the crown component and the skirt component. Embodiments are described having ceramic inserts of silicon nitride and including combustion bowls.

Abstract: Pistons are described having improved stiffness of the lower skirt regions to improve piston guidance and oil film distribution. The pistons comprise a crown portion including piston ring grooves and a skirt portion, the skirt portion being divided into an upper skirt region and a lower skirt region and wherein on each side of the plane including the piston axis and the gudgeon in axis the support skirt region includes at least one bearing surface and the lower skirt region comprises a bearing surface supported by two substantially planar skirt wall sections lying in planes forming an acute angle of less than 75.degree. with the plane which includes the piston and gudgeon pin axes, the maximum bearing contact arc of the lower skirt bearing surface lying between 10.degree. and 22.5.degree. either side of the lane which is normal to the gudgeon pin axis and which includes the piston axis.

Abstract: A piston generates reduced noise in operation by the provision on its lateral bearing surfaces of two or more depressions in which oil is stored to provide a cushion against lateral movement of the piston at points of a reciprocation of the cycle where noise is generated. The depressions have a maximum depth of only 125 microns below the surrounding bearing surfaces formed on the piston. The depressions have circumferentially extending edges which are formed with steps connecting the depressions to the surrounding bearing surface.

Abstract: A piston has skirt portions (13) which are provided with parallel rows (14) of cavities (15) whose maximum depth below the surface of the skirt portion is 0.010 mm. Parts (20,23) of the skirt portion are left between the cavities for providing a reduced area, in comparison with the full skirt portion, for the transmission to an associated cylinder or liner of lateral loads; this reduced area reducing the frictional losses. The cavities (15) hold lubricating oil and provide a cushion of oil which supplies oil to the reduced bearing areas and which tends to resist lateral movement of the piston at top and bottom dead center, so reducing or eliminating "piston slap".

Abstract: A method is disclosed of manufacturing a piston having a skirt on which are formed a plurality of bearing surfaces, each bearing surface being at a predetermined axial position on the skirt, being spaced outwardly of the skirt to a required radial dimension and extending around the skirt with a required circumferential dimension. The method comprises forming the bearing surfaces in at least two stages. First a plurality of projections are formed on a skirt of the piston with each projection being at an axial position in which a bearing surface or surfaces are to be located. The radial and/or axial dimension of the projection exceeds the required corresponding dimension or dimensions of the bearing surfaces. A second step then forms bearing surfaces of the required dimensions. A second form of piston is formed with cylindrical portions which are alternately offset to one side or other of the piston axis to form, one each side of the piston, alternate projecting bearing surfaces and recessed skirt portions.