Expansion bolt with nut actuated expansion wedges

Claim 1

AN ANCHOR BOLT FOR ANCHORAGE IN A WALL OPENING, COMPRISING A BOLT MEMBER OF CIRCULAR CROSS-SECTION HAVING AN EXTERNALLY THREADED PORTION AT ONE END AND IN ITS OUTER SURFACE AT LEAST TWO CIRCUMFERENTIALLY SPACED RECESSES WEDGE SHAPED IN SECTION LENGTHWISE OF THE BOLT MEMBER, EACH OF SAID RECESSES BEING CONTINUED BY A GROOVE EXTENDING INTO AT LEAST PART OF THE THREADED BOLT PORTION, TO ANCHOR MEMBERS INSERTED IN SAID RECESSES LONGITUDINALLY DISPLACEABLE THEREIN IN EITHER DIRECTION, EACH OF SAID ANCHOR MEMBERS BEING ALSO WEDGE SHAPED LENGTHWISE OF SAID BOLT MEMBER AND FITTING IN ONE LONGITUDINAL POSITION THE CIRCUMFERENCE OF THE BOLT MEMBER BUT RADIALLY PROTRUDING THEREFROM IN ANOTHER LONGITUDINAL POSITION, A GUIDE MEMBER FITTED IN EACH OF SAID GROOVES SECURED AT ONE END TO THE RESPECTIVE ANCHOR MEMBER AND PROTRUDING WITH THE OTHER END INTO SAID THREADED BOLT PORTION, AND AN ACTUATING MEMBER FOR SLIDABLY ADVANCING SAID ANCHOR MEMBERS TOWARD THE OTHER END OF THE BOLT MEMBER, SAID ACTUATING MEMBER COMPRISING AN INTERNALLY THREADED SLEEVE SCREWED UPON SAID THREADED BOLT PORTION, ONE END OF SAID SLEEVE BEING ENGAGEABLE WITH THE PORTIONS OF THE GUIDE MEMBERS PROTRUDING INTO THE THREADED BOTH PORTION FOR AXIALLY ADVANCING THE GUIDE MEMBERS AND RADIALLY EXTENDING THE ANCHOR MEMBERS INTO A POSITION IN WHICH THE LATTER PROTRUDE FROM THE CIRCUMFERENCE OF THE BOLT MEMBER UPON SCREWING SAID SLEEVE TOWARD SAID RECESSES, WHEREBY THE ANCHOR MEMBERS FRICTIONALLY ENGAGE A WALL DEFINING SAID OPENING AND UPON RETRACTION OF THE BOLT MEMBER AND THE SLEEVE IN RESPONSE TO AN OUTWARDLY DIRECTED PULL, THE ANCHOR MEMBERS ARE FORCIBLY PRESSED AGAINST SAID WALL, SAID SLEEVE TERMINATING AT ITS END OPPOSITE THE END COACTING WITH SAID GUIDE MEMBERS IN A FLAT SCREW HEAD POSITIONED TO BE SUBSTANTIALLY FLUSH WITH THE OUTER RIM OF SAID WALL OPENING IN SAID ADVANCED POSITION OF THE SLEEVE.