This application claims priority to an earlier filed United States Application Serial No. 08/426,081 filed 21 April, 1995.

FIELD OF INVENTION This invention relates to a method and apparatus for a theft resistant fastener which can be used to fasten one member to another member, as for example to fasten a cover plate to a base member.

BACKGROUND OF THE INVENTION

Alternative technology is available in the form of U. S. Patent No. 1,300,275 issued to Johnson in April, 1919 which reveals a combination of a screw having a single hole eccentric with respect to the axis of the screw and a removable driving key having an eccentric pin adapted to enter the full length of said screw. Unlike the present invention, a hole is exposed relative to the head of the screw. U.S. Patent No. 4,569,259 issued to Rubin et al. on February 11, 1986 discloses an automobile wheel cover locking bolt and wrench combination wherein the head of the locking bolt has a plurality of axial slots, or lock impressions, about its periphery which may be spaced in accordance with a preselected code. The wrench socket is provided with a corresponding number of key elements projecting inwardly from the cylindrical wall of the socket, the position of the key elements being in accordance with a matching preselected code. Additionally, the head of the locking bolt has an axial recess and the socket of the wrench has an axial pin adapted to align and fit within the recess of the bolt. All of the recesses are visible from the top plane view of the bolt.

U.S. Patent No. 2,372,269 issued to Golan on March 27, 1945, relates to a socket wrench and cooperating theft resistant nut with fully extending slots and grooves.

A brake tool disclosed in U.S. Patent No. 5,003,681 by Schley in 1991 reveals a disc like tool having a pin disposed to engage a depression in the surface of a piston.

An anti-theft apparatus including a screw with an anti-theft safety head is disclosed in U.S. Patent No. 4,964,773 dated October 23, 1990 issued to

Schmidt. The disclosed device is for a screw with an extended head that is arranged and adapted to support a locking device which may freely rotate if not set in a locking position. Thus, the head freely rotates relative to the screw preventing the screw from being removed unless the head is first locked thereto. Unlike the present invention, the head is not removable, but merely rotatable about the screw and the structure disclosed is considerably different.

A patent issued to Burge on June 7, 1977, U.S. Patent No. 4,027,572 reveals a theft resistant screw fastener with both the tool and the nut having axial recesses which accommodate a dowel arranged and adapted to have one of its ends disposed in the recess of the nut and the other in the recess of the tool.

Some of the drawbacks to these designs are that each teaches fasteners that are more readily removable by theft since indentations which can be easily grasped are exposed. Moreover, none of the foregoing inventions is designed to be theft resistant in a surface recess (i.e. a countersunk borehole sized to accommodate the socket body of the wrench).

The citation of the foregoing publications is not an admission diat any particular publication constitutes prior art, or that any publication alone or in conjunction with others, renders unpatentable any pending claim of the present application. None of the cited publications is believed to detract from the patentability of the claimed invention.

ADVANTAGES OF THIS INVENTION

To alleviate this problem, and others which will become apparent from the disclosure which follows, the present invention conveniently provides a method and apparatus for fastening a theft resistant screw having a head with a

top surface that is free of any engageable indentations or protrusions, with an independent means to drive the screw.

The independent means to drive the screw is provided in terms of a wrench having a socket and a movable plug that fits into a cavity created by the alignment of a recess in the outer cylindrical wall of the screw head and a socket recess in the inner wall of the socket. Whereby, a plug engaged in the recess of the inner wall of the socket acts as a means to -drive a cylindrical headed screw having a complementary recess disposed in an outer wall of the cylindrical head. An advantage is revealed in a preferred embodiment of the movable plug of the invention which reveals an elongated plug whose thickness is less than the distance between the inner wall and the outer wall of the socket body. This facilitates the removal of the plug from a countersunk borehole in the first of two members that are to be fastened together. In instances where the countersunk borehole (for example, in a cover plate or other article to be fastened to a second member) is sized only nominally larger than the socket body and the head of die screw is only nominally smaller than the inner wall of the socket, then the plugs must necessarily be of limited thickness, otherwise it will not be possible to remove the plug from the cavity defined by the wall of the countersunk borehole when the screw is fully fastened in said borehole.

In a preferred mode, the head diameter of the screw and socket body diameter would be engineered to rninimize the wall thickness of the side wall of the socket, and thus limit the thickness of the plugs. This would inhibit theft of a screw imbedded in a surface with a countersunk borehole slightly larger than the outer diameter of the socket body, as the limited distance between the head and the outer wall of the countersunk hole would limit access to an extraneous tool.

Still other advantages will be apparent from the disclosure that follows.

SUMMARY OF THE INVENTION

The invention relates to a method and apparatus for a theft resistant fastener for fastening two members together comprising a screw having a shank and a generally cylindrical head disposed concentrically on an end of the shank. The generally cylindrical head has an outer side wall with an upper edge and a lower edge. The lower edge is proximate to the shank and the outer side wall has at least one recess extending longitudinally from its lower edge to a spaced distance from its upper edge. An independent means to drive the screw is further provided. The independent means comprises an elongated wrench having an axially disposed socket at one end. The socket has an inner cylindrical wall with at least one recess disposed longitudinally. The wrench further comprises at least one detachable plug suitably sized and adapted to engage the recess disposed longitudinally along the inner cylindrical wall and a means for tethering each detachable plug to the wrench. Each of the detachable plugs is movable between a first position, in which the detachable plug is disposed within the socket where it may engage the recess disposed longitudinally along the inner cylindrical wall thereof, and a second position, in which the detachable plug is disposed outside of the socket. One embodiment of the fastener is specifically designed to fasten a cover plate for an aperture in a wall to a retaining bar located behind the wall, with the wall grasped tightly between the cover plate and retaining bar.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described hereinafter with reference to the accompanying drawing wherein:

FIG. 1 is an exploded perspective view of a first preferred embodiment of the apparatus for a theft resistant fastener of the present invention showing a wrench having a socket disposed on one end with two movable plugs extending outside of the socket which plugs can be engaged to the longitudinal recesses

shown in the outer cylindrical wall of the head of a screw shown prior to fastening.

FIG. 2 is a perspective view of the first preferred embodiment of the apparatus for a theft resistant fastener of the present invention showing the threaded shank of the screw exposed from the socket of the wrench and with the movable plug actuator having been drawn away from me socket forcing the plugs into engagement with the socket and screw head.

FIG. 3 is a perspective view of the first preferred embodiment of the apparatus for a theft resistant fastener of the present invention showing the socket of the wrench partially disposed within the borehole of the cover.

FIG. 4 is a perspective view of the first preferred embodiment of the apparatus for a theft resistant fastener of the present invention showing the head of the screw disposed in the borehole of the cover.

FIG. 5 is a cross-section view taken along line 5-5 of FIG. 1, showing the cylindrical shape of the outer wall of the socket, the generally cylindrical shape and longitudinal recesses of the inner wall of the socket, and the sleeve for the cable to be guided through.

FIG. 6 is a cross-section view taken along line 6-6 of FIG. 1, showing the generally cylindrical shape and longitudinal recesses of the outer wall of the head of the screw.

FIG. 7 is a cross-section view taken along line 7-7 of FIG. 3, showing the shank of the screw disposed through a cover plate and in threaded engagement with a base to which the cover plate is fastened, the plugs disposed in a cavity formed by the alignment of the recess in the inner cylindrical wall of the socket and the recess in the outer side wall of the head of the screw, the terminus of the recess in the outer side wall of the head of the screw at a spaced distance from its upper edge, the screw head disposed in the socket, and the socket body disposed in the borehole of the cover plate.

FIG. 8 is a cross-section view taken along line 8-8 of FIG. 7, showing in plan view the plugs disposed in the cavities formed by the alignment of the recesses in the inner cylindrical wall of the socket and the corresponding

recesses in the outer side wall of the head of the screw, the relationship between the diameter of the screw head and the socket in which it is disposed, and the relationship between the diameter of the outer cylindrical wall of the socket body and the borehole of the cover plate in which it is disposed. FIG. 9 is a front elevation view of the theft resistant fastener of this invention used to secure a cover plate over an aperture in the side wall of a hollow lamp post.

FIG. 10 is a cross-section view taken along line 10-10 in FIG. 9.

FIG. 11 is a cross-section view taken along line 11-11 in FIG. 9. FIG. 12 is a front elevation view of another embodiment of the apparatus of this invention showing a cover plate over an aperture in the wall of a hollow pedestal that supports a hollow lamp post.

FIG. 13 is a cross-section view taken along line 13-13 in FIG. 12. FIG. 14 is a cross-section view taken along line 14-14 in FIG.

13.

DETAILED DESCRIPTION OF THE INVENTION

The preferred embodiments depicted in the drawing include an apparatus for a theft resistant fastener for fastening two members together comprising a screw 1 having a shank and a generally cylindrical head 3 disposed concentrically on an end of the shank. The generally cylindrical head 3 has a top surface 18 with a circular peripheral edge, a bottom surface 7 with a peripheral edge, the bottom surface 7 is disposed proximate to the shank, and an outer side wall which is smooth with an upper edge and a lower edge, the top surface 18 having its peripheral edge connected to the upper edge of the outer side wall and the bottom surface 7 having its peripheral edge connected to the lower edge of the outer side wall, and the outer side wall has at least one recess 5 extending longitudinally from its lower edge to a spaced distance from its upper edge. The top of the recess 7a is shown in Fig. 6. It is designed to be used with a removable tool which is described below.

As one example of two members that can be fastened together with the method and apparatus of this invention, the accompanying drawing shows a cover plate 28 (Figs. 1-4, 7 and 8) fastened to a base 42 (Fig. 7). It will be understood, of course, that this invention will be useful in fastening together any appropriate types of articles or members.

Without departing from the generality of the invention disclosed herein, the screw 1 of the apparatus could easily have a head 3 of varying configurations that could not easily be removed without a complementary, mating tool. The discussion that follows, without limiting the scope of the invention, will refer to the invention as depicted in the drawing.

There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto. Those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

Theft Resistant Fastener A preferred embodiment of the screw 1 of the invention is shown in Fig. 1. It shows an apparatus for a theft resistant fastener comprising a screw 1 having a shank and a generally cylindrical head 3 disposed concentrically on an end of said shank. The generally cylindrical head 3 has an outer side wall with an upper edge and a lower edge. The lower edge is proximate to the shank and the outer side wall has at least one recess 5 extending longitudinally from its lower edge to a spaced distance from its upper edge.

A preferred feature of the screw 1 of the invention teaches a top surface 18 of the head 3 which is free of any engageable indentations or engageable protrusions.

The apparatus for a theft resistant fastener further provides for an independent means to drive the screw 1. One such preferred embodiment of the means to drive the screw 1 is a wrench 2 having a screw head-receiving socket 32 (best seen in Figs. 5, 7 and 8). Modifications will be obvious to those skilled in the art. As shown in Fig. 1, the wrench has a handle 22 and a handle extension 20 to facilitate rotation. Fig. 7 shows an axial tooling recess 36 in the upper wall of the socket.

A preferred embodiment of the wrench 2 of this important invention comprises a wrench 2 having a socket 32, where the socket 32 is defined by an upper surface having a peripheral edge and an inner wall 40 having an upper edge connected to the peripheral edge of the upper surface. The inner wall 40 has at least one socket recess 33 disposed longitudinally. Additionally, the wrench 2 further comprises a movable plug 14 suitably sized and shaped to engage one of the socket recesses 33 disposed longitudinally along the inner wall 40. As depicted in Fig. 5, the inner wall 40 of the socket 32 is generally cylindrical. The socket 32 has a socket body 6 having an outer wall 8 with an upper edge and a top 10 with a peripheral edge; the upper edge of the outer wall 8 being connected to the peripheral edge of the top 10. As shown in Figs. 1 and 2, the outer wall 8 of die socket body 6 is generally cylindrical in its preferred form. The bottom rim 38 of the socket body 6 is shown in Fig. 5. Referring to Fig. 5, the socket 32 is defined by an upper surface having a peripheral edge and an inner wall 40 having an upper edge connected to the peripheral edge of the upper surface. The inner wall 40 has a plurality of socket recesses 33 disposed longitudinally. Referring to Fig. 1 , the wrench 2 further comprises a corresponding number of movable plugs 14, each being suitably sized and shaped to engage one of the socket recesses 33 disposed longitudinally along the inner wall 40, as shown in Fig. 8.

The wrench 2 may further comprise a means for tethering each movable plug 14 to the wrench 2. The means for tethering each movable plug 14 to the wrench 2 may allow each movable plug 14 to move between a first position, in which the movable plug 14 is disposed within the socket 32 where it may engage the socket recess 33 disposed longitudinally along the inner wall 40 thereof, and a second position, in which the movable plug 14 is disposed outside of the socket 32.

As shown in the drawing, a preferred embodiment of the means for tethering each movable plug 14 may comprise a flexible cable 12 and wherein the socket body 6 has a means for guiding the cable. As best shown in Fig. 7, the top of the socket body 6 has a means for guiding the cable. The cable 12 is routed through the guide means and has a proximate end attached to the movable plug 14 and a distal end that is disposed outside d e socket body 6 proximate to the top thereof. As shown in Fig. 7, the guide means may comprise a sleeve 34 for each cable 12. The distal end of the cable 12 is manually actuable to move the plug 14 between its first and second positions. Such distal end may be configured, as shown in Figs. 1 , 2 and 3 to extend die cable 12 into a loop to serve as a cable actuator 4.

A preferred embodiment of me movable plug 14 of the invention reveals an elongated plug 14 whose thickness is less than the distance between die inner wall 40 and die outer wall 8 of the socket body 6. This facilitates the removal of the plug 14 from a countersunk borehole 30. In instances where the countersunk borehole 30 of a cover plate 28 or other article is sized only nominally larger than the socket body 6 and die head 3 of the screw 1 is only nominally smaller than the inner wall 40 of the socket 32, then the plugs 14 must necessarily be of limited tiiickness, otherwise it will not be possible to remove the plug 14 from the cavity defined by die wall 29 of the countersunk borehole 30 when the screw 1 is fully fastened in said borehole. In a preferred mode, the head diameter of the screw and socket body diameter would be engineered to minimize the wall thickness of the side wall of the socket, and thus limit the thickness of the plugs. This would inhibit theft of a screw

imbedded in a surface with a countersunk borehole slightly larger than the outer diameter of die socket body, as the limited distance between the head and die outer wall of the countersunk hole would limit access to an extraneous tool.

Where the screw 1 has its recess 5 extending along the entire length of the outer wall 8 of die head, die thickness of the plug 14 may be larger in lateral dimension. Anotiier preferred embodiment of die screw 1 provides that the head 3 has an outer side wall with at least one recess 5 extending longitudinally along the length thereof.

As shown in Figs. 1 and 7, die plugs 14 and socket 32 of the wrench 2 attach to the screw 1 disclosed. As pointed out above, an exemplary use of the method and apparatus of this invention ~ to fasten a cover plate 28 to a base 42

— is also disclosed in Fig. 7.

Method For Producing Theft Resistant Fastening An embodiment of the method for producing a theft resistant fastening of a first member to a second member comprises the following steps: a. moving a movable plug 1 of a wrench 2 having a socket body 6 witii a socket 32 that has an inner wall 40 that has a socket recess 33 disposed longitudinally, to a position in which die movable plugs 14 are disposed outside of die socket; b. engaging the movable plug 14 disposed outside of die socket to the recess 5 extending longitudinally along an outer wall 8 of a generally cylindrical head 3 of a screw 1 diat has a threaded shank 16, the generally cylindrical head 3 has a top surface 18 with a peripheral edge, a bottom surface 7 with a peripheral edge, die bottom surface 7 is disposed proximate to die shank, and an outer side wall with an upper edge and a lower edge, the top surface 18 having its peripheral edge connected to the upper edge of die outer side wall and d e bottom surface 7 having its peripheral edge connected to die lower edge of the outer side wall, and each of the recesses 5 extends longitudinally from its lower edge to a spaced distance from its upper edge;

c. positioning the socket recess 33 on the inner wall 40 of the socket in alignment with the engaged plug 14 disposed along the recess 5 of the outer wall 8 of the head 3 of die screw 1 ; and d. bringing together the cylindrical head 3 of die screw 1 with the plug 14 engaged thereto and die socket, permitting the engaged plug 14 to be disposed in the socket recess 33 disposed longitudinally along the inner wall 40 of the socket.

In another embodiment of the metiiod of the present invention the following steps are provided: a. moving a moveable plug 14 of a wrench 2 having a socket body 6 with a socket that has an inner wall 40 that has a socket recess 33 disposed longitudinally, to a position, in which die movable plugs 14 are disposed outside of die socket; b. engaging the movable plug 14 disposed outside of die socket to the recess 5 extending longitudinally along an outer wall 8 of a generally cylindrical head 3 of a screw 1 that has a threaded shank 16, die generally cylindrical head 3 has a top surface 18 with a peripheral edge, a bottom surface 7 with a peripheral edge, die bottom surface 7 is disposed proximate to the shank, and an outer side wall with an upper edge and a lower edge, d e top surface 18 having its peripheral edge connected to die upper edge of the outer side wall and die bottom surface 7 having its peripheral edge connected to die lower edge of die outer side wall, and each of the recesses extends longitudinally from its lower edge to a spaced distance from its upper edge; c. positioning the socket recess 33 on the inner wall 40 of the socket in alignment with the engaged plug 14 disposed along the recess 5 of the outer wall 8 of the head 3 of die screw 1; d. bringing together the cylindrical head 3 of die screw 1 with the plug 14 engaged tiiereto and die socket, permitting the engaged plug 14 to be disposed in the socket recess 33 disposed longitudinally along the inner wall 40 of the socket;

e. positioning die tiireaded end of die shank of the screw 1 through a bore having a countersunk borehole 30 of sufficient diameter to accommodate die socket body 6 and of axial lengtii greater than the lengtii of the recess 5 extending along the outer wall 8 of the generally cylindrical head 3 of the screw l.

Anodier preferred embodiment of die metiiod of die present invention comprises the following steps: a. moving a moveable plug 14 of a wrench 2 having a socket body 6 with a socket that has an inner wall 40 that has a socket recess 33 disposed longitudinally, to a position, in which the movable plugs 14 are disposed outside of d e socket; b. engaging the movable plug 14 disposed outside of the socket to the recess 5 extending longitudinally along an outer wall 8 of a generally cylindrical head 3 of a screw 1 that has a threaded shank, the generally cylindrical head 3 has a top surface 18 with a peripheral edge, a bottom surface

7 with a peripheral edge, die bottom surface 7 is disposed proximate to die shank, and an outer side wall witii an upper edge and a lower edge, the top surface 18 having its peripheral edge connected to die upper edge of the outer side wall and the bottom surface 7 having its peripheral edge connected to die lower edge of die outer side wall, and each of the recesses extends longitudinally from its lower edge to a spaced distance from its upper edge; c. positioning the socket recess 33 on the inner wall 40 of the socket in alignment with die engaged plug 14 disposed along the recess 5 of the outer wall 8 of the head 3 of die screw 1 ; d. bringing together the cylindrical head 3 of die screw 1 with the plug

14 engaged tiiereto and die socket, permitting die engaged plug 14 to be disposed in the socket recess 33 disposed longitudinally along the inner wall 40 of the socket; e. positioning the tiireaded end of die shank of the screw 1 through a bore having a countersunk borehole 30 of sufficient diameter to accommodate the socket body 6 and of axial lengtii greater than die length of the recess 5

extending along the outer wall 8 of the generally cylindrical head 3 of die screw 1; and f. freeing die moveable plug 14 from die recess 5 of the head 3 of the screw 1 and withdrawing the moveable plug 14 of the wrench 2 from die countersunk borehole 30 of the cover plate 28, thereby disengaging the wrench

2 from the screw 1.

In another preferred embodiment of me method of tiύs invention die following steps are provided: a. moving each of a plurality of movable plugs 14 of a wrench 2 having a socket body 6 witii a socket that has an inner wall 40 that has a corresponding number of socket recesses 33 disposed longitudinally, to a position, in which d e movable plugs 14 are disposed outside of die socket; b. engaging each of d e movable plugs 14 disposed outside of the socket to a recess 5 extending longitudinally along an outer wall 8 of a generally cylindrical head 3 of a screw 1 that has a threaded shank, the generally cylindrical head 3 has a top surface 18 with a peripheral edge, a bottom surface 7 with a peripheral edge, die bottom surface 7 is disposed proximate to the shank, and an outer side wall with an upper edge and a lower edge, die top surface 18 having its peripheral edge connected to d e upper edge of die outer side wall and the bottom surface 7 having its peripheral edge connected to the lower edge of die outer side wall, and each of the recesses extends longitudinally from its lower edge to a spaced distance from its upper edge; c. positioning the socket recesses 33 on the inner wall 40 of the socket in alignment with die engaged plugs 14 disposed along the recesses of the outer wall 8 of die head 3 of die screw 1; and d. bringing together the cylindrical head 3 of die screw 1 with the plugs 14 engaged thereto and the socket, permitting die engaged plugs 14 to be disposed in die socket recesses 33 disposed longitudinally along the inner wall 40 of the socket. Another embodiment of me metiiod of the present invention comprises the following steps:

a. moving a movable plug 14 of a wrench 2 having a socket body 6 witii a socket that has an inner wall 40 that has a socket recess 33 disposed longitudinally, to a position in which d e movable plugs 14 are disposed outside of die socket; b. engaging the movable plug 14 disposed outside of die socket to die recess 5 extending longitudinally along an outer wall 8 of a generally cylindrical head 3 of a screw 1 that has a threaded shank, the generally cylindrical head 3 has a top surface 18 with a peripheral edge, a bottom surface 7 with a peripheral edge, die bottom surface 7 is disposed proximate to the shank, and an outer side wall with an upper edge and a lower edge, die top surface 18 having its peripheral edge connected to the upper edge of die outer side wall and d e bottom surface 7 having its peripheral edge connected to d e lower edge of die outer side wall, and each of the recesses extends longitudinally from its lower edge to a spaced distance from its upper edge; c. positioning die socket recess 33 on the inner wall 40 of the socket in alignment with die engaged plug 14 disposed along die recess 5 of the outer wall 8 of the head 3 of die screw 1 ; d. bringing together die cylindrical head 3 of die screw 1 with die plug 14 engaged tiiereto and die socket, permitting die engaged plug 14 to be disposed in die socket recess 33 disposed longitudinally along the inner wall 40 of the socket; e. positioning die threaded end of the shank of the screw 1 through a bore having a countersunk borehole 30 of sufficient diameter to accommodate me socket body 6 and of axial lengtii greater than the length of die recess 5 extending along the outer wall 8 of the generally cylindrical head 3 of die screw

1; f. driving the screw 1 into threaded engagement with a threaded bore 44 of a base 42, thereby securing the screw 1 and cover plate 28 to the base 42; g. axially withdrawing die socket of the wrench 2 from the countersunk borehole 30 of the cover plate 28, allowing die engaged plug 14 to remain engaged to die recess 5 of the head 3 of die screw 1; and

h. freeing the movable plug 14 from the recess 5 of the head 3 of the screw 1 and witiidrawing the movable plug 14 of die wrench 2 from die countersunk borehole 30 of the cover plate 28, thereby disengaging die wrench 2 from die screw 1. Another preferred method of die present invention, which can be easily visualized by reference to the drawing, comprises the following steps: a. moving each of a plurality of movable plugs 14 of a wrench 2 having a socket body 6 with a socket that has an inner wall 40 that has a corresponding number of socket recesses 33 disposed longitudinally, to a position in which the movable plugs 14 are disposed outside of d e socket; b. engaging each of the movable plugs 14 disposed outside of die socket to a recess 5 extending longitudinally along an outer wall 8 of a generally cylindrical head 3 of a screw 1 that has a threaded shank, the generally cylindrical head 3 has a top surface 18 with a peripheral edge, a bottom surface 7 with a peripheral edge, die bottom surface 7 is disposed proximate to the shank, and an outer side wall with an upper edge and a lower edge, die top surface 18 having its peripheral edge connected to the upper edge of d e outer side wall and die bottom surface 7 having its peripheral edge connected to die lower edge of die outer side wall, and each of the recesses extends longitudinally from its lower edge to a spaced distance from its upper edge; c. positioning the socket recesses 33 on the inner wall 40 of the socket in alignment with d e engaged plugs 14 disposed along die recesses of the outer wall 8 of the head 3 of die screw 1; d. bringing together die cylindrical head 3 of the screw 1 with die plugs 14 engaged tiiereto and die socket, permitting the engaged plugs 14 to be disposed in the socket recesses 33 disposed longitudinally along die inner wall 40 of the socket; e. positioning the threaded end of die shank of die screw 1 through a bore having a countersunk borehole 30 of sufficient diameter to accommodate the socket body 6 and of axial lengtii greater than the length of the recesses

extending along the outer wall 8 of the generally cylindrical head 3 of die screw l; f. driving die screw 1 into threaded engagement witii a threaded bore 44 of a base 42, thereby securing the screw 1 and cover plate 28 to the base 42; g. axially withdrawing the socket of the wrench 2 from the countersunk borehole 30 of the cover plate 28, allowing the engaged plugs 14 to remain engaged to d e recesses 5 of the head 3 of die screw 1; and h. freeing the movable plugs 14 from the recesses 5 of the head 3 of die screw 1 and wid drawing the movable plugs 14 of the wrench 2 from die countersunk borehole 30 of the cover plate 28, tiiereby disengaging die wrench

2 from the screw 1.

Another preferred embodiment of me metiiod of the present invention comprises the following steps: a. moving each of a plurality of movable plugs 14 of a wrench 2 having a socket with an inner cylindrical wall that has a corresponding number of socket recesses 33 disposed longitudinally, to a position in which the movable plugs 14 are disposed outside of die socket; b. engaging each of the movable plugs disposed outside of die socket to a recess 5 extending longitudinally along an outer cylindrical wall of a generally cylindrical head 3 of a screw 1 diat has a tiireaded shank; c. moving the engaged plugs and die cylindrical head 3 of die screw 1 into the socket in a manner that permits the movable plugs to engage the socket recesses 33 disposed longitudinally along the inner cylindrical wall of the socket; d. positioning the threaded end of die shank of the screw 1 through a bore having a counter sunk borehole disposed in an exposed surface of a cover plate 28 and into pre-engagement contact witii a tiireaded hole in a base 42; e. driving die screw 1 into threaded engagement witii die base 42, thereby securing the screw 1 and cover plate 28 to the base 42; and

f . axially withdrawing the plugs and socket of the wrench 2 from the counter sunk borehole of the cover plate 28, thereby disengaging the wrench 2 from die screw 1.

Fastener for Plate Covering Aperture in Wail

One example of the use of the tiieft resistant fastener of this invention is to secure a cover plate over an opening in a wall that is to be kept covered for security purposes. This may be, for instance, a cover plate over an aperture in the wall of a hollow metal post that supports a street light at its top end. It is important that the electrical equipment and circuitry within the interior of the hollow pole not be stolen or otherwise tampered witii, and a tiieft resistant cover is very valuable in preserving the security of the system.

Fig. 9 provides a front elevation view of a portion of die fastener of this invention used in this way. (The movable plugs that are an essential part of the fastener, such as plugs 14 shown in Figs. 1 and 7, are omitted for clarity from Figs. 10 and 11.) Figs. 9-11 show a fragmentary portion of a substantially cylindrical wall 50 of a lamp post diat contains equipment and circuitry in its interior. Aperture 52 in the wall, which has a given shape and area, provides die access from the exterior that may be necessary from time to time for maintenance purposes.

In the embodiment shown, cover plate 54 has the general shape of the aperture in the wall. The transverse dimensions of the cover plate measured in all directions are substantially greater than the corresponding transverse dimensions of the aperture. As a result, the aperture is completely covered by die cover plate.

When the cover plate is in its position covering die aperture, it is held centered over the aperture by a positioning ledge diat extends for eitiier (1) at least a portion of die perimeter of the cover plate or (2) at least part of the wall portions surrounding die aperture. A complementary protrusion is provided on die other member. In the embodiment of Figs. 9-11, ledge 55 of cover plate 54 comprises the positioning member, and wall portions 57

adjoining aperture 52 act as a complementary protrusion that engages the ledge witii a close fit.

The aperture is covered by cover plate 54, which as already indicated has substantially the same shape as the aperture, but a somewhat larger area. It is preferred tiiat, as in the embodiment shown, the configuration of die outer surface of the portions of die wall surrounding die aperture and the configuration of die inner surface of the outer portions of the cover plate be such that die two members will form a good fit when they are assembled togedier. The cover plate is fastened to the wall by theft resistant fasteners

56 and 58 acting in cooperation with retaining bar 60 (to be further described below), which is located witiiin the interior of the lamp post. The illustrated cover plate achieves a complete closing of the aperture, and provides security against theft or tampering with die equipment or circuitry inside die post. (As will be seen, cover plate 54 and retaining bar 60 in Figs. 9-11 correspond to first member 28 and second member 42, respectively, in Figs. 1-4 and 7.)

For some applications otiier tiian the lamp post under discussion, die necessary security against theft or tampering may be provided by only partial coverage of the aperture. In such cases, it will be sufficient if the cover plate has a maximum transverse dimension mat is substantially greater than the smallest transverse dimension 61 of the aperture. This will permit the cover plate to be installed in a position bridging across the aperture and to cover at least a substantial portion of the area of the aperture, which in certain cases may be sufficient even though the aperture is not completely closed. As best seen in Fig. 10, in the illustrated embodiment mere are two boreholes 62 and 64, witii countersunk portions 66 and 68, located in cover plate 54 to receive screws 70 and 72, respectively. The countersunk portions have a predetermined deptii and a predetermined radius.

Cover plate 54 is held in place by screws 70 and 72, which have tiireaded shanks 74 and 76, respectively. The heads of the screws are generally cylindrical and are disposed concentrically on the end opposite the threaded end

of shanks 74 and 76. The radius of each screw head (for example, radius 72a in Fig. 11) is less than the radius of die countersunk portion (radius 68a in Fig. 11) of die corresponding borehole in cover plate 54 by an amount that is predetermined by the desired thickness of movable plugs 14 (Figs. 1 and 7). The top surface 77 of each screw head (like the top surface 18 of screw head 3 in Figs. 1 and 4) is free of any engageable indentations and free of any engageable protrusions. (The term "engageable" is used in this specification and the accompanying claims to mean engageable with a wrench, screwdriver, pliers or similar tool by which the screw can be turned about its axis.) In die embodiment shown, the top surface of each screw head is flat.

The height 78 of each screw head (see Fig. 10), measured axially above the shank, should not be substantially greater than the deptii of die countersunk portions 66 and 68, respectively, of the corresponding borehole in the cover plate. In the embodiment of Figs. 9-11, the height of each screw head is equal to approximately one-half the depth of each countersunk portion

66 and 68. This position of the top of die screw head makes it extremely difficult for any unauthorized person to attempt to reach down into the space between the screw head and the inner wall of the countersunk portion and somehow engage the recesses in the screw head in order to loosen the screw. Bottom surfaces 80 and 82 of die heads of screws 70 and 72, respectively, have a generally annular shape. The side wall of each screw head has at least one recess 84 and 86, respectively, each of which extends from the bottom surface of the screw head, witii its top end located a spaced distance from the top surface of the screw head. As will be seen, the greater this spaced distance is, the more difficult it will be for any unauthorized person to attempt to reach down into die space surrounding die head of die screw to engage die recesses in the screw head in order to loosen the screw.

In the embodiment of Figs. 9-11 (as well as the embodiment of Figs. 1-8), a recess of substantially the same shape and dimensions is contained (but not shown in the drawing) in the screw head side walls diametrically opposite the recesses that are shown in the drawing. If desired, only one recess

need be provided in each screw head, or a greater number than two — such as six recesses equally spaced circumferentially — may be included in each screw head. The recesses may be of any suitable shape that permits plugs 14 to move in and out of engagement therewith. There can be any desired number of boreholes in the cover plate and any desired pattern of such holes. Thus, in some cases in which the apparatus of this invention is to be employed, a single fastener, or several fasteners, may be used in place of the two fasteners designated as 56 and 58 in Figs. 9 and 10. The retaining bar of the fastener of this invention will in such cases contain only one threaded borehole, or more than two, depending upon die number of fasteners used, but in each case arranged in die same pattern as the boreholes in the cover plate.

In Figs. 9-11, retaining bar 60 is positioned vertically, and has a length substantially greater than the maximum vertical dimension 88 of aperture 50. Depending upon d e degree of closure desired, and the positioning of die retaining bar with respect to the vertical axis of the aperture, the length of the bar may be less, but in every case must be substantially greater than the smallest transverse dimension 61 of die aperture. Retaining bar 60 contains threaded boreholes 90 and 92, equal in number and pattern of distribution to boreholes 62 and 64 in the cover plate, and tiireaded to receive die threaded ends of shanks 74 and 76 of die fastening screws. Inner face 94 of retaining bar 60 may be a flat surface. It is preferred, however, diat it be slightly rounded, to conform to the curvature of inner wall 96 of generally cylindrical wall 52. This is best seen in Fig. 11, which is a cross-section view taken along line 11-11 in Fig. 9.

As will be seen, cover plate 54 and retaining bar 60 correspond to die first and second members 28 and 42, respectively, diat are fastened together by the theft resistant fastener of this invention shown in Fig. 7. The tool for tightening screws 70 and 72 in the threaded boreholes of retaining bar 60 is the wrench shown in Figs. 1-3, 5, 7 and 8.

Wrench 2 has a handle portion ~ in the embodiment illustrated in the Figures

just mentioned, members 20 and 22 ~ with a generally cylindrical socket body 6 secured to die handle portion. The socket body defines socket 32, which has a generally cylindrical inner wall 40. The open end of d e socket faces away from the handle portion. Inner wall 40 has at least one recess 33 extending inward into the socket from the open end of die socket.

At least one movable plug 14 is provided, each of which is suitably sized and shaped to engage simultaneously one of said at least one recess (designated 5 in Figs. 1, 4, 6 and 8, and 84 and 86 in Fig. 10) in die outer wall of the screw head, and one of said at least one recess (designated 33 in Figs. 5, 7 and 8) on inner wall 40 of the socket, when the screw head is positioned witiiin the socket. As will be seen from Figs. 1 and 7, in the embodiment shown each movable plug 14 is elongated in shape. In order to avoid having to cut the recesses in the inner wall of the socket body too deep, it is preferred that thickness 98 of plugs 14 be no greater that thickness 98' of the substantially cylindrical wall of socket body 6 (see Fig. 8).

Each plug is suitably sized and shaped to pass between the screw head and d e inner wall of the countersunk portion of the boreholes in the first member (for example, member 28 in Figs. 1-4, 7 and 8, and cover plate 54 in Figs. 9-11), when (1) the screw is fully seated in one of die threaded boreholes in die second member (member 42 in Figs. 1-4, 7 and 8, and retaining bar 60 in Figs. 8-11) and (2) socket body 6 has been removed from the countersunk portion in the first member.

Wrench 2 also includes support member 12 for adjustably securing each of the least one movable plug to socket body 6 to permit the plug to move between a first position in which it is disposed within the socket in simultaneous engagement with the recesses in the screw head side wall and die socket inner wall, and a second position in which the movable plug is disposed outside of die socket. In the embodiment shown, support member 12 is a U- shaped flexible cable. The cable is routed through opening 34 in socket body 6. The proximate end of each branch of the cable is attached to one of the movable plugs, and die distal, U-shaped end is disposed above and outside d e

socket, manually actuable to move the plugs between their first and second positions. Opening 34 through which the cable is routed keeps the cable operatively connected to die socket body at all times.

Cover plate 54 can be installed in its place on wall 50 shown in Fig. 10, by a series of steps, the first steps being executed solely by hand and the rernaining steps being performed utilizing the wrench shown in Figs. 1-3, 5, 7 and 8. Upper screw 70 can be first inserted tivrough borehole 62 in the cover plate and loosely threaded by hand into threaded borehole 90 in retaining bar 60. Next, the bottom end of die retaining bar can be inserted into aperture 52 and lowered sufficiendy to allow the upper end of the bar to be positioned witiύn the aperture. The cover plate can then be held in a vertical position and die retaining bar permitted to move in a pendulum motion about upper screw 70, to position itself so that lower threaded borehole 92 in the bar is in line with lower screw 72. Cover plate 54 can then be moved into its approximate final position within aperture 52, and lower screw 72 loosely threaded by hand into threaded borehole 92 in the retaining bar.

Next, socket body 6 of wrench 2 is positioned over upper screw head 70, witii one of recesses 33 on inner wall 40 of the socket aligned witii one of recesses 84 in the upper screw head to produce a pair of aligned recesses. As shown in Figs. 1 and 2, one of movable plugs 14 is then drawn into engagement with the pair of aligned recesses, by pulling upward on cable actuator 4.

With the parts in question assembled as indicated, wrench 2 is turned to tighten die upper screw in the retaining bar. When the screw has been tightened securely in place, wrench socket 6 can be withdrawn, which will permit movable plugs 14 to be withdrawn through the space between the top portion of screw head 70 and the inner wall of the countersunk portion 66 of borehole 62. The tightening of the screw by use of wrench 2 and die removal of the wrench can be repeated for lower screw 72. The procedure outlined can be reversed to remove lower screw

72, loosen upper screw 70, withdraw die cover plate from aperture 52 a short

distance, rotate the retaining bar, and remove the loosely connected cover plate and bar entirely from the aperture.

Figs. 12-14 illustrate still another embodiment of die apparatus of this invention employed to provide security for the electrical equipment and wiring located in the interior of a hollow lamp post. In this embodiment, post

100 is supported on a hollow pedestal in the form of a four-sided truncated pyramid 102, which in turn rests upon -concrete surface 104.

Rectangular aperture 106 in pedestal wall 108 is securely closed by cover plate 110. Ledge 112 extends around the entire perimeter of aperture 106, and peripheral portions 114 of cover plate 110 form a close fit with the ledge along its entire length.

Outer surface 116 of the cover plate and outer surface 118 of pedestal wall 108 lie in the same plane. The coplanar relationship just described, which results from the close fit between ledge 112 extending around aperture 106 and die peripheral portions 114 of the cover plate, is maintained by (1) die tight engagement between inner surface 119 of wall 108 and angled feet 121 and 122 adjacent either end of retaining bar 120, which is disposed in a generally horizontal position adjacent die upper portion of die aperture, and (2) the tight engagement between surface 119 and angled feet 123 and 124 at the bottom of the aperture.

Feet 121 and 122 ensure diat, if wall 108 in a particular installation happens to be considerably thinner than shown in Figs. 13 and 14, die main body of die retaining bar will not come into contact with boss 128 on the cover plate and interfere with die close fit between wall 108 and die cover plate at ledge 112 in die wall and peripheral portions 114 of die cover plate.

Borehole 126 is countersunk at 130. With the cover plate installed in place, screw shank 132 extends through borehole 126 in the cover plate, and screw head 133 is seated in countersunk portion 130. Corresponding members are seen on the right-hand side of Fig. 14. As seen in Figs. 13 and 14, die cover plate is installed securely in place when threaded portions 136 and 138 of the two fastening screws are fully

threaded into the corresponding tiireaded boreholes 140 and 142 adjacent eitiier end of retaining bar 120. With die fastening screws in this position, recesses 144 and 146 in the two screw heads are located deep within the countersunk portions of the boreholes in the cover plate. While this invention has been described in connection witii die best mode presentiy contemplated by die inventor for carrying out his invention, the preferred embodiments described and shown are for purposes of illustration only, and are not to be construed as constituting any limitations of the invention. Modifications will be obvious to those skilled in me art, and all modifications diat do not depart from me spirit of die invention are intended to be included within the scope of the appended claims.

My invention resides not in any one of these features per se, but rather in die particular combination of all of them herein disclosed and claimed and it is distinguished from the prior art in this particular combination of all of its structures for the function specified.

These togedier witii otiier objects of the invention, along with die various features of novelty which characterize the invention are pointed out witii particularity in die claims annexed to and forming a part of this disclosure. For a better understanding of die invention, its operating advantages and die specific objects attained by its uses, reference should be had to die accompanying drawings and descriptive matter in which there is illustrated preferred embodiments of the invention.

With respect to the above description tiien, it is to be realized diat the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in die drawings and described in the specification are intended to be encompassed by d e present invention.