| 摘要 |
PROBLEM TO BE SOLVED: To cut a whistling noise produced when pressure oil passes through a communicating hole. SOLUTION: This elevator hydraulic device is so constituted that a small diametral tube is extended in a first piston installed in a cylinder tube, a second piston is installed in this small diametral tube, a piston rod is extended in this second piston upward, the piston rod is projected from an upper end of the small diametral tube in which a communicating hole 7a interconnecting the inside and outside of this small diametral tube, is formed and then pressure oil is sealed in a clearance between the small diametral tube and the first piston plus the piston rod as well as a clearance between the cylinder tube and the small diametral tube. In this case, the communicating hole 7a is made up of a mid small diametral hole 14, each taper part 9 expanding toward the outside at both ends of this small diametral hole 14 and a large diametral hole 10 being almost the same diameter as an outer edge 15 of this taper part 9. |
