CUSHION DEVICE FOR HYDRAULIC CYLINDER

摘要

PROBLEM TO BE SOLVED: To improve the lubrication in a sliding surface between a cushion ring and a flow passage inner wall forming a cushion flow passage when cushion-stroking, and to suppress the temperature rise of the fluid flowing in this cushion flow passage. SOLUTION: A piston rod 22 connected to a piston 21 sliding inside of a cylinder tube 20a of a cylinder 20 is provided with a ring fitting part 22b, and a cushion ring 28 is installed in a floating condition. The peripheral surface of the cushion ring 28 is formed with narrow-width and relatively shallow circumferential grooves 32. Three circumferential grooves 32 are provided in the axial direction of the cushion ring 28 with a nearly equal pitch, and function as oil sumps, showing the oil temperature rise preventing function and the lubricating film holding function.