Alongside the reader mast of the enlargement

摘要

PROBLEM TO BE SOLVED: To surely open and close enlarging excavating blades utilizing the rotation of a rotating shaft, eliminate the need of an opening and closing drive source with high output, enable the opening and closing by a considerably simple opening and closing mechanism, enables an increase in the diameter, and enables the visual confirmation of the opening and closing in an enlarging/contracting and opening/closing device for the enlarging excavating blades for constructing an enlarged foot protection bulb at the end of a pile.;SOLUTION: An opening and closing operation tool 20 formed of an outer ring 32 with female screw/an inner ring 33 with male screw is fitted to the upper part of the rotating shaft 4. An operation rod 21 vertically movable along the rotating shaft 4 and rotatable together with the rotating shaft is installed. The rotation of the outer ring 32 is stopped by stopping the normally and reversely rotating rotating shaft 4 by a rotation stop means 34. Since the inner ring 33 is lifted along the rotating shaft 4 while rotating it through a screw, the enlarging excavating blades are enlarged/contracted and opened/closed by lifting the inner ring 33 to vertically move the operation rod 21.;COPYRIGHT: (C)2008,JPO&INPIT