| 摘要 |
PURPOSE:To suppress the amount of sinking due to the compression of air and oil by installing, in the hollow part of a plunger, a filling-up member having a passage for introducing the pressurized oil into the upper part of the plunger, and forming an air vent in the upper part of the plunger. CONSTITUTION:In the hollow part of a plunger 4A, a hole 13 for introducing pressurized oil into the upper part of the plunger 4A, and a filling-up member 17 having a conical concaved part 20 are installed, and an air vent 19 is formed in the upper part of the plunger 4A. Therefore, air can be discharged-out perfectly, and the amount of oil which intrudes into the plunger 4A can be reduced. Thus, the amount of sinking due to the compression of air and oil can be suppressed.
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