Shear-head security bolt - has conical groove machined in bolt head which is sheared off under excessive tightening torque

摘要

The two items to be fixed together are drilled to take the bolt (1) with a nut (4). The security bolt is used to give a vandal-proof fixing and has a specially machined head. The head may be slotted (2), hexagonal or socketed and has a slot (3) machined in it. The slot has a conical root with the smaller diameter adjacent to that face of the head in contact with the work piece (7). Under excessive tightening torque the top of the head is sheared off leaving a plain, flat section.