| 摘要 |
<p>PROBLEM TO BE SOLVED: To prolong the lifetime of a seal ring by preventing the push-in of a seal ring into a liquid return hole. SOLUTION: A seal ring 9 to be installed in pistons 7, 8 has a cup-shaped seal 40 made of an elastic member, of which lip part 43 is directed toward pressure chambers 12, 22 in a tip side thereof, and a sliding ring 50, which is made of the material harder than that of the cup-shaped seal 40 and in which the lip part 43 elastically contacts with the inner peripheral surface 50b thereof and of which outer peripheral surface 50a slide-contacts with a side peripheral inner wall 4c of a cylinder hole 4.</p> |
