Patent ID: 8061935

Claim:
A rock bolt comprising first and second ends, a shaft extending between the ends, and an anchoring device extending along a first part of the shaft adjacent the first end, the anchoring device comprising a mandrel, and at least one expansion element overlaying the mandrel, wherein the at least one expansion element is displaced radially outwardly on a predetermined relative movement between the mandrel and the at least one expansion element, wherein the at least one expansion element is joined to a connector to form an anchor assembly, said anchor assembly being keyed to the mandrel, and said anchor assembly comprising relative rotation actuator means active during rotation of the anchoring device; wherein the connector includes a body section and at least one connecting leg, the relative rotation actuator means including one or more tags that extend from the at least one leg, the one or more tags being adapted to be passive during rotation in a first direction and active during rotation in a second direction; wherein the one or more tags are arranged to not grip the wall surface of a drilled hole when the bolt is rotated in the first direction, and to grip the wall surface when the bolt is rotated in the second direction so as to enable anchoring of the anchoring device, thereby inducing the predetermined movement.