Expansion anchor

Claim 1

An expansion anchor comprising: a. a hollow body portion and an expansor adapted to enter and expand said body portion; b. said body portion having a head at one end and a plurality of legs arranged in pairs and extending longitudinally from said head toward the opposite end of said body portion; c. the legs constituting each pair of legs being integrally connected to the head and to each other at their respective upper ends adjacent the head and being further integrally connected to each other at their respective lower ends, and being free from each other intermediate said upper and lower ends; d. each pair of legs being also free from the other pairs of legs throughout their entire length except at their upper ends where they are integrally connected to the head; and e. all of said legs being relatively flexible and free to bow inwardly intermediate their respective ends upon insertion into a bore and being free to bow outwardly intermediate their respective ends upon insertion of the expansor. f. the expansor being a screw-threaded member having a head with a screwdriver-engaging formation; g. a longitudinally extending rib being formed on the outer surface of one leg of each pair of legs; h. the ribbed legs alternating with the unribbed legs; i. the ribbed legs being caused to bow inwardly to a greater extent than the unribbed legs when the body portion is inserted into a bore; and j. thereby forming inwardly projecting, longitudinally extending splines on alternate legs of the body portion which are readily engageable by the threads of the expansor.