Drilling latch apparatus

Abstract

A drilling tool, for example a core barrel inner tube assembly or a drilling bit, is attached to the inner end of a latch body which is removably seatable on a landing shoulder of a drill string. A latch retractor is mounted to the latch body for limited axial movement and has a latch assembly chamber opening inwardly to the closed end of the tubular portion of the latch body. The latch assembly includes a rigid transverse link that at opposite ends dependingly pivotally mount a pair of latches, there being no mechanical attachment of the assembly to the retractor or latch body. A transverse stop member limits the latch lateral sections movement inwardly toward the other from a latch seated position to a latch retracted position. At the inner end of the retractor, there are angularly spaced flanges extending radially toward the other in the chamber for retracting the latches as the retractor is withdrawn. The flanges are spaced to permit the assembly being extended therebetween and into the chamber. After the latches are extended angularly between the flanges and moved axially into the chamber, the latches are retracted and rotated about the central axis about 90 degrees, the retractor is extended into the tubular portion and the stop member is mounted to the latch body to extend between the latches.