Abstract: A tightening device for threaded screw part having an engaging part to be engaged with the threaded screw part to be tightened and a main body continuous with the engaging part, wherein a groove is formed on at least one surface portion of the engaging part and a small passage is formed within the main body of the tightening device in the axial direction thereof with the rear end thereof being closed, both groove and small passage being aligned in the axial direction of the main body, and an elongated, bow-shaped plate spring having a tapered surface at the front tip end thereof is inserted into the small passage along the groove so that its rear end may be stopped at the innermost part of the small passage and its front end may be substantially in flush with the tip end of the engaging part, whereby, at the time of tightening the threaded screw part, the engaging part firmly grasps the head of the threaded screw part to facilitate the tightening operation.

Abstract: A tightening device for threaded screw part having an engaging part to be engaged with the threaded screw part to be tightened and a main body continuous with the engaging part, wherein a groove is formed on at least one surface portion of the engaging part and a small passage is formed within the main body of the tightening device in the axial direction thereof with the rear end thereof being closed, both groove and small passage being aligned in the axial direction of the main body, and an elongated, bow-shaped plate spring having a tapered surface at the front tip end thereof is inserted into the small passage along the groove so that its rear end may be stopped at the innermost part of the small passage and its front end may be substantially in flush with the tip end of the engaging part, whereby, at the time of tightening the threaded screw part, the engaging part firmly grasps the head of the threaded screw part to facilitate the tightening operation.

Abstract: A tightening device for threaded screw part having an engaging part to be engaged with the threaded screw part to be tightened and a main body continuous with the engaging part, wherein a groove is formed on at least one surface portion of the engaging part and a small passage is formed within the main body of the tightening device in the axial direction thereof with the rear end thereof being closed, both groove and small passage being aligned in the axial direction of the main body, and an elongated, bow-shaped plate spring having a tapered surface at the front tip end thereof is inserted into the small passage along the groove so that its rear end may be stopped at the innermost part of the small passage and its front end may be substantially in flush with the tip end of the engaging part, whereby, at the time of tightening the threaded screw part, the engaging part firmly grasps the head of the threaded screw part to facilitate the tightening operation.