| 摘要 |
<p>A piston generates reduced noise in operation by the provision on its lateral bearing surfaces (15) of two or more depressions (18) in which oil is stored to provide a cushion against lateral movement of the piston at points of a reciprocation cycle where noise is generated. The depressions have a maximum depth of only 125 microns below the surrounding bearing surface and may be provided in discrete bearing surfaces (23, Fig. 2) formed on the piston. The depressions have circumferentially extending edges (19) which are formed with steps (20) connecting the depression to the surrounding bearing surface.</p> |
