SEALING DEVICE FOR PISTON ROD

PROBLEM TO BE SOLVED: To provide a sufficient oil scraping performance by providing a combined oil scraping ring constructed of a ring type coil spring, which is mounted in a ring type groove part in an expanded condition and presses a supporting column part inward in the diameter direction so as to bring the inner circumferential end faces of an upper rail member and a lower rail member into pressure contact with the outer circumferential face of a piston rod. SOLUTION: In an oil scraping ring 1, an upper rail member 2 and a lower rail member 3 are connected together by means of a supporting column part, 4, and in a trough part 6, an expanded ring type coil spring 7 is mounted while being brought into contact with a tilting face constituting the trough part, 6 without any interference with an oil flow hole. By compressing force of the ring type coil spring 7, the supporting column part 4 is pressed inward in the diameter direction, inner circumference ends of the upper rail 2 and the lower rail 3 are brought into pressure contact with the outer circumferential face 14 of a piston rod 8, and an oil scraping action from the piston rod circumferential face can be carried out effectively. In this way, consumption of lubricating oil is reduced, while a frequency of part replacement can be lowered.