Lock'n Bolt | Screw thread + wedge

The bolt has a through hole axially and a cone-shaped tip end. The end part of the screw has two slits to expand the tip radially. A cone-shaped piece is inserted into the tip end of the bolt and the piece is tightened from the head of the bolt by a cap bolt. Consequently, the end part of the screw is expanded radially and the screw thread of the bolt cut into that of the piece, which prevents loose. 
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