Importance

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Abstract

Core drilling apparatus that includes a wire line core barrel inner tube assembly movable through a drill stem to be seated in a latched core taking position adjacent the drill stem core bit and an overshot assembly coupled to the inner tube assembly for lowering and/or withdrawing the inner tube assembly in the drill stem. The inner tube assembly includes an overshot coupling assembly having a base member extended into the latch release tube for limited movement relative thereto, a spearpoint assembly connected to the base member for pivotal movement through an angle of about 180.degree. about a transverse pivot axis, and a detent plunger resiliently mounted by the subassembly to extend into a base recess when the central axes of the base and coupling members are nearly aligned to releasably retain said members in relative positions that their axes are aligned, and to abut against a base tapered surface when the subassembly central axis is at a substantial angle relative the base central axis.

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First Claim