| 摘要 |
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. |
