PISTON FOR PISTON-CYLINDER UNIT

PURPOSE: To facilitate the installation of a piston ring by forming a plurality of piece parts separated mutually by means of vertical slits in a part of a piston extending from a piston ring groove to a free end in a gas shock absorbing device. CONSTITUTION: In a guiding piston 6 fixed in a piston rod 4 for connecting a damping part 20 integrally with a guiding body 15 brought into slide contact with a casing inside wall, a piston ring groove 26 and a headed conical hole are provided, and by means of a plurality of slits 24 (four slits, for example) extending from the piston ring groove 26 to a free end 22, a plurality of piece parts 23, whose hole 21 sides are covered by a film 25 in connection, are arranged on a conical outside wall 31. A piston ring 34 made of hard resin material is inserted from the free end 22 in the damping part 20 with an outside diameter substantially equal to an inside diameter di of the piston ring 34 so as to be installed into the groove 26. Then, a piston shaft 4 is inserted into the hole 21 so as to be expanded in a diameter, and the piston shaft 4 is fixed when a part of it is crushed by a recess part 17. In this way, a piston ring can be installed with ease.