| 摘要 |
PROBLEM TO BE SOLVED: To provide a special center-push device, for efficiently constructing center-push propulsion, by smoothly passing through a curve section, in propulsion construction including a curve.SOLUTION: A step height part of an outer cylinder 2 having the diametrically reduced step height part 3 in a front tip part and extending a cylindrical front ring body 4 being long backward, is inserted into a collar of a front propulsion pipe, and a cylindrical connection cylinder 5 having a diameter smaller than an inner diameter of the front ring body of the outer cylinder, is inserted so as to abut via a cushion material 7 on a front wall surface of the front ring body, and the front wall surface of a storage cylinder of an insertion cylinder 8 having the cylindrical storage cylinder 9 in the substantially same diameter as an outer diameter of the connection cylinder and slightly shorter than the length of the front-rear propulsion pipes and fixing a cylindrical socket cylinder 10 in the same diameter as the collar of the propulsion pipe in the rear, is inserted into the front ring body, and is inscribed so as to contact with a rear wall surface of the connection cylinder via the cushion material, and a plurality of center-push jacks 11 are arranged in the storage cylinder. |
