Patent ID: 6948417

Claim:
A fluid cylinder with a swivel joint comprising a cylinder tube, a piston fitted into said cylinder tube to be slidable in said cylinder tube, and a piston rod in which with a part at a rod front end portion side being protruded outside said cylinder tube and said piston being integrally fitted thereon, a protrusion amount of said part at the rod front end portion side to an outside of said cylinder tube is changed according to entrance and exit of fluid into and out of a chamber at a rod side and a chamber at a side opposite the rod inside said cylinder tube, an entire body being extended and contracted according to a change in said protrusion amount, said cylinder comprising a pin hole, into which a pin provided at another member is fitted, and relative rotation of said cylinder tube around said pin is freely made during extension and contraction of the cylinder, said cylinder further comprising a first opening, which is non-annular and provided in an outer circumferential surface of said pin, a second opening, which is non-annular and provided in an inner circumferential surface of said pin hole, and always opposes said first opening even when said cylinder tube relatively rotates around said pin, a third opening provided in an end surface of said pin, and a swivel flow passage having a first flow passage provided inside said pin and leading from said first opening to said third opening, and a second flow passage leading from said second opening into said chamber at said rod side and said chamber at said side opposite the rod inside said cylinder tube, in which said first flow passage and said second flow passage always communicate with each other via said first opening and said second opening even when said cylinder tube relatively rotates around said pin, wherein said second flow passage is provided inside said piston rod.