Abstract: An expansion anchor is used in a hole in a receiving material where the hole is undercut. The expansion anchor includes an axially elongated anchor sleeve containing slots extending in the axial direction. Expansion interlock members are radially displaceably mounted in the slots. A fastening bolt can be threaded into the sleeve so that it radially displaces and secures the interlock members in the undercut portion of the hole. Each interlock member has a shaped surface facing radially inwardly in the sleeve and the shaped surface is contacted by the fastening bolt as it is moved into the sleeve. The trailing end of the shaped surface is formed so that it is not contacted by the fastening bolt as the bolt is moved through the sleeve.

Abstract: An expansion dowel assembly includes an axially elongated expansion sleeve with an axially extending expansion region, a spreader positioned within the sleeves in the expansion region, and a bolt in threaded engagement within a tapped bore in the spreader so that the spreader can be displaced axially through the expansion region for widening it in the radial direction. The surface of the spreader in surface contact with the interior of the sleeve is spherically shaped. In the assembled state, before expansion, the spreader is held in the expansion sleeve against axial displacement. Accordingly, the parts of the assembly can be preassembled as a unit.