Telescopic hydraulic cylinder with rotatable piston rod

The invention relates to the field of hydraulic device manufacturing, in particular to a telescopic hydraulic cylinder with a rotatable piston rod. The telescopic hydraulic cylinder comprises a telescopic cylinder barrel, wherein the piston rod is mounted in the telescopic cylinder barrel; the front end of the piston rod extends out of the end part on one side of the telescopic cylinder barrel; a cylinder bottom is fixedly mounted at the end part on the other side of the telescopic cylinder barrel; the rear end of the piston rod is sealed in the telescopic cylinder barrel by the cylinder bottom; a through hole is formed in the inner edge of the cylinder bottom; a blind hole is formed in the rear end part, which is located on the same side as the through hole, of the piston rod and is aligned with the through hole; a gear shaft is mounted on the inner side of the blind hole; the piston rod and the gear shaft can concentrically rotate at the same speed; the rear end part of the gear shaft passes through the through hole in the cylinder bottom; a swinging cylinder barrel is fixedly mounted at the rear end part of the cylinder bottom in a direction perpendicular to the telescopic cylinder barrel; a rack is mounted in the swinging cylinder barrel; the rack is engaged with the rear end part, which is located outside the cylinder bottom, of the gear shaft; and oil ports are formed in the side wall of the telescopic cylinder barrel and the swinging cylinder barrel respectively.