| 摘要 |
PROBLEM TO BE SOLVED: To provide an extending/contracting or opening/closing device of extended excavation blades of an extended head for constructing a foot protecting pedestal at the tip of a pile, which can positively open and close the extended excavation blades by using the rotation of a rotating shaft, dispenses with an opening/closing driving source generating a large output, achieves opening/closing operation by a relatively simple opening/closing mechanism, can extend a diameter to an arbitrary value, and allows an operator to check an opening/closing state by visual observation. SOLUTION: The extending/contracting or opening/closing device has an opening/closing operating jig 20 arranged on an upper portion of the rotating shaft 4, which is composed of a male screw shaft 30, a female screw ring 31, and a base ring 32, and an operating rod 21 arranged so as to be vertically movable along the rotating shaft 4 and rotatable together with the rotating shaft. Then rotation of the female screw ring 31 with respect to the rotating shaft 4 which is rotatable forward and backward is stopped by a rotation stopping means 35, and the female ring 31 is ascended and descended by the spiral rotation of the male screw shaft 30, and the operating rod 21 is vertically moved by the ascent/descent of the female screw ring 31, to thereby extend and contract or open and close the extended excavation blade. COPYRIGHT: (C)2008,JPO&INPIT
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