| 摘要 |
<p>A fastener which can be rotated in one direction using an attaching tool but not in the other direction, the fastener comprising a shank portion, a collar portion, and a head portion, the collar portion being positioned immediately below the head portion and providing support for part of the head portion, the head portion having a central raised portion and a pair of opposed shoulder portions, each shoulder portion extending from the central raised portion and towards a peripheral edge of the collar portion, each shoulder portion having an attaching tool engaging face on one side of the shoulder portion and an attaching tool sliding face on the other side of the shoulder portion the construction and arrangement of this being to enable the attaching tool to engage with the engaging face on each shoulder portion to enable the fastener to be tightened, unable to engage with the head portion and/or shoulder portions when rotated in the other direction thereby preventing the fastener from being loosened.</p> |
