| 摘要 |
PURPOSE:To reduce the flow-down amount of sealing liquid by a method wherein a member for preventing rotation of a piston, a movable sealing piece or the like are utilized. CONSTITUTION:When a piston 4 is rotated, a circumferential gap is caused between a rotation preventing member 15 and a sliding seal member 9, however, the movable seal piece 20 is pressed to both sides of the rotation preventing member 15 of the piston by the energized force of a spring 22 to hold said gap in constant and, thus, the flow-down amount of the seal liquid is held in constant. A clearance between the sliding seal member 9 and the member 15, which is generated by the wear of the seal member 9, is compensated by the movable seal piece 20 and thereby enabling to keep a stable sealing performance for a long period of time. |
