In the circular sulcus where

摘要

PROBLEM TO BE SOLVED: To restrain frictional resistance of a rod seal backed up by an O-ring from being increased. ;SOLUTION: In a hydraulic cylinder, a rod seal 18 for sealing a piston rod 3 extending from a piston in a cylinder is bounce-energized to the piston rod 3 by an O-ring 19 arranged outside it. Step parts 45, 46 are provided on the inner peripheral surface and the outer peripheral surface of the rod seal 18, protrusions 47, 48 capable of being fitted to the step parts 45, 46 are provided on a main body 30 for constituting a rod guide and a cover body 31. In a case where energizing force is increased after the O-ring 19 is strongly compressed after differential pressure between a cylinder inner chamber and an oil accumulating chamber 22 for accumulating leaked oil is increased, the energizing force is shared to the protrusions 47, 48, and therefore, the rod seal 18 is prevented from being pressed to the piston rod 3 with strong force.;COPYRIGHT: (C)1998,JPO