To prevent falling, uneven wear and cracks by contracting force in the radial direction of a rod seal of a cylinder device having a part sliding with a piston rod and a non-sliding part with the piston rod on an inner periphery.
A sealing structure in a part in which a piston rod 3 is projected from a cylinder 1 is constituted by a double sealing mechanism 44 of the rod seal 42 and an O-ring 19. The rod seal 42 is formed by a difference in level part 41 which does not slide with the piston rod 3 and a seal part 40 sliding with the piston rod 3 and the rod seal 42 performs sealing by contracting force of the rod seal 42 itself and force energized by the O-ring 19. On an end face of the rod seal 42, an annular groove 43 for lowering rigidity for the radial direction is provided and contracting force (recovering force) in the radial direction after an assembling is weakened.
NAGAO WATARU
OKADA HIROKI
