| 摘要 |
<p>A shearable fastener having a threaded shank adapted for engagement with a threaded bore and a head portion formed for engagement with a drive tool, the shank being formed with a series of axially separated weakenings defining a series of shear planes, wherein the weakenings are formed such that the applied torque necessary to cause the shank to shear increases progressively from the shear plane furthest from the head portion to the shear plane nearest the head portion, characterized in that the weakenings comprise holes, grooves or slits formed in the shank and the radius at the bottom of the holes, grooves or slits is varied to produce or contribute to the said increase in shear torque.</p> |
