| 摘要 |
<p>A kelly bar has a spigot 2 and socket 3 where the spigot 2 includes a male part and the male part has an extension tang 14 extending from the spigot 2. The extension tang 14 has a radial bore 10 where the bore has a portion 10 with a smaller diameter than another portion 11. The first portion 10 is tapered towards an interface between the first 10 and second 11 portions.</p> |
