Expansion dowel with sleeve and expansion member

Expansion dowel with an axially extending expansion sleeve (1) having a leading end and trailing end with axially extending slots (3) open at the leading end and a bore (2) extending between the leading and trailing ends and tapering inwardly at least for an axial part thereof to the leading end, an expanding member (5) for expanding said expansion sleeve and having a leading end and a trailing end (5b) and insertable into said bore (2), said expanding member (5) has an exterior surface tapering inwardly at least partially towards the leading end of said expanding member, said expanding member (5) has a recess open at the leading end thereof for purposes of partial radial deformation, wherein the improvement comprises that said expanding member having an initial position before expansion of said sleeve is commenced located within said bore spaced between and from the leading and trailing ends thereof and a final position after expansion of said sleeve spaced towards the leading end from the initial position and spaced by a uniform dimension (X) from the trailing end of said sleeve the recess of said expanding member (5) is an axially extending blind bore (6) having a leading end at the leading end of said expanding member and a trailing end with said trailing end of said blind bore located closely spaced from said trailing end of said expanding member and forming a closed said trailing end of said expanding member, said expanding member (5) has a lug (7) centered on and formed integrally with said closed trailing end (5b) thereof and projecting axially from the trailing end of said expanding member (5), and an axial projection of a transverse cross section of said lug lies within an axial projection of a transverse cross section of a region (6a) of the blind bore (6) adjacent the closed trailing end thereof, and said closed trailing end of said expanding member and said axially projecting lug affording an axially extending rated annular failure point, and said axially projecting lug and said closed trailing end of said expanding member adapted to be driven into said blind bore (6) towards the leading end of said expanding member after breakage of said rated annular failure point following advancement of said expanding member within said bore (2) towards said leading end of said expansion sleeve.