| 摘要 |
<p>A down hole running tool (14) travels in a first direction through a drill pipe for installing bit segments (18) at the end of a drive sub (12) attached to the drill pipe. The tool (14) includes a first portion (82) and a second portion (84) which is retractably coupled to a leading end of the first portion (82). The first portion (82) includes a tubular extension (134) which receives a spigot (136) that extends from an upper end of the second portion (84). A pin (138) extends transversely through the tubular extension (134) and resides within opposing slots (140) formed in the spigot (136). There is a stepped reduction in the internal diameter at the lower end of the tubular extension (134) so as to form a cup-like structure (146). A spring (168) is disposed about the spigot (136) and has an upper end seated in the cup-like structure (146) and a lower end bearing against an upper face (170) of the second portion (84). The spring (168) is biased so as to push the first and second portions (82 and 84) apart in the longitudinal direction. When the tool (14) is lowered into the drive sub (12) and the second portion (84) hits a stop, the first portion (82) is able to continue movement for a short distance against the bias of the spring (168) by virtue of a gap existing between the surface (170) and the end of the cup-like structure (146).</p> |
