US Patent 9676115 Guide bar fastening device for chain saw

To provide an operation lever including a first lever that has a base end portion swingably supported to a peripheral portion of a nut member for fastening a guide bar in a chain saw, and a second lever that is engaged with the first lever in a manner slidable in an axial direction. The operation lever can be placed in a receiving portion of the nut member with an axial length thereof shortened, and can be manipulated to rotate the nut member by being gripped on an outer end portion of the second lever in a state in which the operation lever is lifted out from the receiving portion and the axial length is lengthened. Thus, a sufficient fastening force for the guide bar can be obtained, and operability can be improved.