Patent attributes
A stopper mechanism includes a second cylinder provided at an end portion in an inner cylinder, and a second piston configured to move along with movement of a piston rod to be capable of being fit-inserted through the second cylinder. The second piston includes a stopper coupled to the piston rod, a castle integrated with the stopper by plastic flow to form a ring groove on an outer periphery of the second piston between the castle and the stopper, and a piston ring fixed into a ring groove formed by the stopper and the castle so that the piston ring is displaceable in the ring groove in an axial direction and is retained in the ring groove, and has an annular shape with both ends in a circumferential direction which are formed by partially cutting the piston ring.
