Patent ID: 7036400
Filing Date: 2006-05-02
Classification: B25B

Abstract:
1. A wrench for tightening or loosening a fastening member having a cylindrical hole with respect to another member, comprising: a wrench body having a cylindrical body to be inserted into the cylindrical hole of the fastening member and a handle portion projecting from the cylindrical body; a plurality of wedge members each assuming a roller-like shape; a retainer disposed outside the cylindrical body in such a manner that the retainer rotates around an outer circumferential surface of the cylindrical body, the retainer rotatably holding the wedge members at predetermined intervals in a circumferential direction of the cylindrical body; wedge guide grooves formed on the outer circumferential surface of the cylindrical body to be arranged along the circumferential direction of the cylindrical body at intervals corresponding to those of the wedge members, each of the wedge guide grooves having a free region which extends in the circumferential direction of the cylindrical body and maintains the corresponding wedge member in a free state in which the wedge member moves freely between a bottom surface of the corresponding wedge guide groove and the inner circumferential surface of the cylindrical hole of the fastening member, and a wedge region which extends in the circumferential direction of the cylindrical body and maintains the corresponding wedge member in a caught state in which the wedge member is caught between the bottom surface of the corresponding wedge guide groove and the inner circumferential surface of the cylindrical hole of the fastening member; and a changeover mechanism for operating the retainer in order to move each wedge member to a position at which the wedge member faces the free region of the corresponding wedge guide groove or a position at which the wedge member faces the wedge region of the corresponding wedge guide groove.