| 摘要 |
PURPOSE:To reduce an oil leak as well as to make slidability between a piston and a cylinder with oil in a concave part, by installing both concave and convex parts on an outer circumferential surface of a plastic band, and giving them a labyrinth effect. CONSTITUTION:Throttling folds of a skirt 26a elastically stick fast to a cylinder in an assembled state. In time of stretching processes, the skirt 26a receives oil pressure and is deformed to the side of the cylinder 1, and in time of contracting processes, a skirt 26b is deformed to the side of the cylinder 1 and sticks fact to it, preventing a leak from occurring. Both concave and convex parts 27 installed on an outer circumference of a plastic band 26 produces a labyrinth effect, restraining an oil leak. And, as for these concave and convex parts 27, oil gathered in the concave part performs a lubricating function between a piston 2 and the cylinder 2, thus slidability is well improved. |
