Importance

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Abstract

A retractable bit system that includes a single piece annular core bit that is movable through a drill string (drill stem), had an outer diameter about the same as that of the drill stem, and can be releasably locked to the drill string, an outer barrel assembly for the drill stem that is operable for lockingly engaging the core bit and driving the core bit, bit replacement tools for moving and core bit through the drill string and operable for operating the outer barrel assembly and replacing the bit on the drill string without removing the drill string from a drill hole, a manually operated surface tool removably mounted on the drill string for clampingly engaging a wire line and retracting the wire line to operate the respective one of the bit installation tool and bit retraction tool when the respective tool extends into the outer barrel assembly, and a safety release tool for operating and withdrawing the replacement tools which will uncouple from the replacement tool when more than a predetermined force is applied.

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First Claim