US Patent 11519448 Rotary fastening device

A rotary fastening device includes a rotating axial member and an inertia member. The rotating axial member includes a base body, an input end, an output end and an engaging portion. The input end is disposed at one end of the base body and selectively connected to a wrench. The output end is disposed at the other end of the base body. The engaging portion is disposed on the base body. The inertia member is detachably connected to the rotating axial member, and includes a gravity portion and an engaging hole. The gravity portion is extended toward the output end of the rotating axial member so as to form an annular space. The engaging hole is communicated to the annular space.