Ball anchor dowel

Claim 1

An expansion dowel for use in a prepared borehole and the like, comprising an axially extending cylindrically shaped shank having a leading end and a trailing end with the leading end arranged to be inserted first into the borehole, said shank being threaded at its trailing end and having a frusto-conically shaped head secured to and extending axially outwardly from the forward end of said shank with the frusto-conically shaped surface widening outwardly from the leading end, an axially extending deformable sleeve laterally enclosing at least a portion of said shank and said sleeve adjacent said head having a maximum inside diameter which is not greater than the largest diameter of said frusto-conically shaped head, said sleeve having a leading end adjacent the leading end of said shank and a trailing end spaced axially from the leading end toward the trailing end of said shank, wherein the improvement comprises that said sleeve from its leading end for a portion of its axial length toward its trailing end is spaced radially outwardly from said shank forming an axially extending annular cavity therebetween, said sleeve having a radially inwardly projecting annular shaped collar extending axially from a plane between the leading end and trailing end of said sleeve toward the trailing end thereof and the radially inner surface of said collar closely fitting the outside diameter of said shank so that said shank can be slidably displaced relative to said collar, the end of said collar closer to the leading end of said sleeve forming a radially inwardly directed annular shoulder forming a closure for the end of said cavity closer to the trailing end of said shank, said head extending into and forming a closure for the leading end of said sleeve so that said cavity is closed in the axial and radial directions, and a plurality of small balls formed of a hard material filled into said cavity so that said balls are disposed in contact with one another and with the inner surface of said sleeve and the surface of said shank within the axially extending range of said cavity and are capable of deforming said sleeve when said head is moved relative to said sleeve inwardly into the cavity within said sleeve.