| 摘要 |
This reciprocating piston, particularly for heat engines, compressors, comprises at least one upper bead the side surface or periphery whereof presents projecting portions and recessed portions. The projecting portions of this periphery have an initial diameter, before running-in, such that the initial diametrical clearance between the periphery of the upper bead and the cylinder, cold, is substantially equal to half the clearance usually provided between the conventional upper bead and cylinder, so that, during the running-in, the projecting portions of the upper, pressed against the inner wall of the cyliner, may contract and be compressed in the recessed portions which absorb them. Further, the piston presents at least one cavity opening on the periphery of the first bead of the piston and at least one mobile piece partially occupying this cavity and which moves therein due to the movement of the piston, to prevent, without other deterioration, any considerable deposits of calamine.
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