Abstract: An insert for releasably retaining drill bit segments in a ground drill takes the form of a cylindrical tube movable within the ground drill between an installation position and a retrieval position. A pair of opposing tapered peaks extends from the upstream end of the insert. Sides of the peaks slope sharply in a downstream direction and lead to flats separating the peaks. When a running tool with radially extending latch dogs travels down the drill, the latch dogs contact the peaks to cause the tool to rotate about its longitudinal axis. When the latch dogs hit the flats they engage the insert, pushing it down into the installation position and locking the bit segments into a cutting position. Another set of latch dogs provided on the tool can engage slots formed in the insert to pull the insert upwardly and release the bit segments.