Abstract: The rockbolt anchoring head comprises a first wedge member with a wedge surface and a passage to receive the rockbolt, and a second wedge member with a complemental wedge surface. The second wedge member is connected to the rockbolt. The wedge surfaces of the first and second wedge members are arranged in slideways relationship with one another, and a spring acts between the members to cause relative slideways movement between the wedge surfaces. In combination, the wedge members form a body which is rectangular in a cross-section taken transversely to the axis of the rockbolt.

Abstract: The roof bolt tendon comprises a length of square twist steel with a partial thread formed directly thereon over at least part of its length. The partial thread, which may extend for the full length of the tendon and which is preferably formed by rolling, is composed of thread portions formed at the corners of the square cross-section of the square twist steel. A roof bolt in which the tendon is employed is also disclosed.