Screw comprises axial recess with undercut, which is formed at end face of screw head in circumferential direction and is designed such that screw tool during driving of screw covers backlash

摘要

The screw has screw head (1) and bolt portion (2) provided with outside thread (3). An axial recess (5) with an undercut (6) is formed at end face (4) of screw head in the circumferential direction. The undercut is in shape of semi circle, triangle or square. The axial recess is designed such that a screw tool (20) during driving of screw covers a backlash. Independent claims are included for the following: (1) a nut; and (2) tool for driving screw.