| 摘要 |
PROBLEM TO BE SOLVED: To facilitate fitting work of a seal ring to a groove of a piston main unit and fitting work of a piston to a cylinder hole, and holding a seal effect, left properly by the seal ring, in assembly work of a cylinder. SOLUTION: A cylinder tube 10 and a piston 13 fitted to a cylinder hole 11 in this cylinder tube 10, so as to be axially slid to partition the cylinder hole 11 into a first/second chamber 14, 15 are provided. This piston 13 comprises a piston main unit 23, having in the external peripheral surface a circular annular groove 24 with the axial center 12 of the piston which serves as the center and an elastic seal ring 25 fitted to a groove 24 with the axial center 12 serving as the center. Of the external peripheral surface of the piston main unit 23, an external peripheral surface, positioned axially in one side from the groove 24 serves as a first external peripheral surface 26. An external peripheral surface positioned in the other side serves as a second external peripheral surface 27. An external diametric dimension D1 of the first external peripheral surface 26 is set smaller than an external diameter dimension D2 of the second external peripheral surface 27. |
