Anti-tamper fastener shielding apparatus

Apparatus for assembly with a screw of bolt-type fastener having a mounting stem and an enlarged head during use of said fastener for deterring and detecting tampering therewith, said apparatus comprising a one-piece integrally molded annular collar means for extension therethrough of said fastener stem and for retained disposition adjacent the underside of said fastener head in assembly with said fastener and closure means adapted to mate with said collar means for cooperatively enclosing said fastener head to deter access thereto, said collar means comprising a jacket member having an annular housing portion having an opening therethrough for receiving said fastener head to be encircled by said housing portion and an annular collar portion constricting said opening for extension through said collar portion of said fastener stem and for disposition of said collar portion adjacent the underside of said fastener head, an annular washer member of an outer diametric dimension smaller than said constricted opening through said collar portion and an axial dimension greater than said collar portion, said washer member being disposed coaxially with said collar portion at the axial side thereof opposite said housing portion for extension through said washer member of said fastener stem and for disposition of said washer member adjacent the underside of said fastener head, and a frangible annular diaphragm member extending radially between said collar portion and said washer member, said diaphragm member being adapted to be sheared under force of engagement of said fastener head with said collar portion upon installation of said fastener in assembly with said collar means to detach said jacket member and said washer member to dispose said washer member radially between said collar portion and said fastener stem for rigid clamping of said washer member by said fastener head while permitting said jacket member to rotate freely about said fastener and said washer member, thereby preventing removal action frictionally upon said fastener by action upon said jacket member, said collar means being integrally molded of a material adapted to break readily in response to gripping force applied exteriorly to said housing portion thereof tending to impose said removal action frictionally upon said fastener head, thereby to enable detection of tampering with said collar means, and said closure means comprising a cap member adapted to securely fit interiorly of said housing portion in flush relation therewith for enclosing said fastener head therewithin.

In combination with a utility meter or the like having a usage measuring assembly, a cover member for protection of said measuring assemby, and a fastener of the type having a stem and an enlarged head holding said cover member in place, the improvement comprising apparatus for assembly with said fastener for deterring and detecting tampering therewith, said apparatus comprising annular collar means for extension therethrough of said fastener stem and for disposition adjacent the underside of said fastener head in assembly with said fastener and closure means adapted to mate with said collar means for cooperatively enclosing said fastener head to deter access thereto, said collar means including an outer annular collar member having an annular collar portion, an inner annular washer member, and frangible means connecting said collar member and said washer member and adapted to break to detach said collar member and said washer member from one another under force of engagement of said fastener head with said collar means upon installation of said fastener in assembly with said collar means, said washer member being of a greater axial dimension than said collar portion for installed engagement of said fastener head with said washer member to permit said collar member to rotate freely about said fastener and said washer member, thereby preventing removal action frictionally upon said fastener by acting upon said collar member.