| 摘要 |
A pressure-balanced system wherein a cylindrical member such as a piston, a shaft, or the like, is movably received in a cylinder bore. Means are provided for balancing the cylindrical member so as to reduce friction between the cylindrical member and the wall of the cylinder bore as may result from a flow of fluid under pressure from an adjacent high-pressure space to an adjacent low-pressure space through the cylinder bore. The balancing means illustratively comprises an annular groove opening to the clearance space between the cylindrical member and the wall of the cylinder bore. In one form, the annular groove is disposed in the cylinder. In another form, the annular groove is disposed in the wall of the cylinder bore. The balancing means may be provided at the end of the clearance space adjacent the high-pressure space, the low-pressure space, or both as desired. Means are provided for causing direct communication between the annular groove and the adjacent pressure space. The communication means illustratively comprises passages in the member in which the annular groove is provided. The illustrated passages comprise bores or laterally opening grooves.
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