Pivot handle for use with expansible hole anchor

Reeves; Eric William

Patent Application Summary

U.S. patent application number 11/879135 was filed with the patent office on 2007-11-08 for pivot handle for use with expansible hole anchor. This patent application is currently assigned to Sigma Industries, LLC. Invention is credited to Eric William Reeves.

Application Number20070257171 11/879135
Document ID /
Family ID46328120
Filed Date2007-11-08

United States Patent Application 20070257171
Kind Code A1
Reeves; Eric William November 8, 2007

Pivot handle for use with expansible hole anchor

Abstract

A pivot handle operable for use with conventional hole anchor devices is provided and generally includes an assembly of links and rockers attached together on opposite sides of the load cable by fasteners. Respective ends of the hole anchor's chock cables are fixed to the rockers. When assembled about the load cable of the hole anchor, the rockers cooperate to allow kink-controlling movement of the chock cables relative to the load cable. The handle rocks or pivots when one chock cable is in tension and the other cable is in compression, thereby discouraging cable kinking or excessive bending which may foul effective operation of the anchor. To facilitate retraction of the handle, finger curves formed with the rockers are also provided.


Inventors: Reeves; Eric William; (Charlotte, NC)
Correspondence Address:
    Jason S. Miller;CLEMENTS WALKER
    Suite 300
    1901 Roxborough Road
    Charlotte
    NC
    28211
    US
Assignee: Sigma Industries, LLC

Family ID: 46328120
Appl. No.: 11/879135
Filed: July 16, 2007

Related U.S. Patent Documents

Application Number Filing Date Patent Number
11069646 Mar 1, 2005 7258316
11879135 Jul 16, 2007
PCT/US04/24129 Jul 27, 2004
11069646 Mar 1, 2005

Current U.S. Class: 248/231.9
Current CPC Class: E04G 21/3261 20130101; A62B 35/0068 20130101; A63B 29/024 20130101; E04G 21/3276 20130101
Class at Publication: 248/231.9
International Class: A47F 5/08 20060101 A47F005/08

Claims



1. An expansible hole anchor adapted for insertion into a hole formed within a structure, said hole anchor comprising: a load cable; a center chock attached to an end of said load cable; at least one side chock adjacent to said center chock and adapted for movement between an anchor-contracting position and an anchor-expanding position; and a pivot handle carried by said load cable and adapted for moving said at least one side chock from the anchor-expanding position to the anchor-contracting position, and whereby in said anchor-contracting position, said anchor is readily inserted into and removed from the hole of the structure, and in said anchor-expanding position, said anchor is locked inside the hole of the structure.

2. The expansible hole anchor according to claim 1, further comprising a chock cable interconnecting said pivot handle and said at least one side chock.

3. The expansible hole anchor according to claim 1, wherein said pivot handle comprises a link assembly movably joined to a rocker assembly for allowing kink-controlling movement of said chock cable relative to said load cable.

4. The expansible hole anchor of claim 3, wherein the link assembly is a plurality of links, each link being joined to a surface of the rocker assembly such that the pivot handle is mounted about the load cable.

5. The expansible hole anchor of claim 3, wherein finger curves are formed with the rocker assembly for facilitating retraction of the pivot handle along the load cable.

6. The expansible hole anchor of claim 3, wherein the rocker assembly comprises at least two rockers having substantially planar top and bottom portions and a side wall.

7. A pivot handle, comprising: at least one rocker assembly; a plurality of links movably joined to the at least one rocker assembly by at least one fastener; and wherein the pivot handle is mounted about a load cable of an expansible hole anchor, and wherein an end of at least one chock cable is fixed to the at least one rocker assembly such that the pivot handle provides kink-controlling movement of the at least one chock cable relative to the load cable.

7. The pivot handle of claim 6, wherein the at least one rocker assembly comprises substantially planar top and bottom portions and a side wall.

8. The pivot handle of claim 7, further comprising finger curves formed with the at least one rocker assembly for facilitating retraction of the pivot handle along the load cable.

9. A pivot handle for use with an expansible hole anchor, comprising: a pair of rockers having substantially planar top and bottom portions and a side wall; a first link movably joined to the top portions of the rockers and a second link movably joined to the bottom portions of the rockers; attachments means for receiving respective ends of a plurality of chock cables such that the pivot handle pivots when one chock cable is in tension and the other cable is in compression, thereby discouraging cable kinking; wherein the pivot handle is movably mounted about a load cable of an expansible hole anchor.

10. The pivot handle of claim 9, wherein at least one bore extending through the top portion to the bottom portion of each rocker is provided for receiving a fastener for movably joining the links to the rockers.

11. The pivot handle of claim 10, wherein the fastener is selected from the group consisting of a rivet, a pin, a screw and a wireform.

12. The pivot handle of claim 9, further including finger curves formed in the side wall of the rockers for facilitating retraction of the pivot handle along the load cable.
Description



CROSS REFERENCE TO RELATED APPLICATION(S)

[0001] This application is a continuation-in-part of U.S. patent application Ser. No. 11/069,646, filed on Mar. 1, 2005, and entitled "EXPANSIBLE HOLE ANCHOR WITH ENLARGED CHOCK-RELEASING STRIKER HEAD," which is a continuation of and claims the benefit of priority of PCT/US04/24129, filed on Jul. 27, 2004, the content of all the aforesaid applications are relied upon and incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to safety devices and methods for fall protection, and more specifically, to safety devices including, in an exemplary embodiment, a pivot handle operable for use with conventional expansible hole anchors and the like.

[0004] 2. Technical Background

[0005] In the construction industry, it is often necessary to provide fall protection for workers or objects suspended at heights. Conventionally, expansible hole anchor bolts are used to meet these needs. Contractors typically utilize the expansible hole anchors in the hopes that they provide a simple, reliable and relatively inexpensive means for connecting a cable, rope or wire to a drilled hole in a hard material, that is easy to install in and remove from the hole, and that effectively anchors to the hole while applying a minimum stress to the hole, while providing a minimum sensitivity to the angular orientation of the expansion bolt in the hole. However, substantial drawbacks and limitations exist in conventional expansible hole anchors, particularly those with retractable handles and/or collars.

[0006] A first shortcoming of conventional hole anchors is that the handle is only applicable for moving the anchor from a normal expanded condition to a contracted condition for inserting and removing the anchor from the hole. In order to remove the anchor, the user is typically instructed to manually retract the handle to disengage the anchor chocks from an inside wall of the hole. In many cases, the anchor is so tightly lodged inside the hole that movement of the handle is difficult, if not impossible. This occurs often, as the operating instructions call for a tug on the load cable to set the anchor during insertion. Additional forces exerted on the anchor caused by a worker movement, or during a worker's fall cause even greater locking engagement of the anchor chocks. The instructions commonly provided for dislodging an embedded anchor are to insert a small, narrow flat screwdriver into the hole, and create an impact force on an end fitting to overcome the locking friction. In practice, this procedure is generally ineffective; often resulting in mangled or broken retraction cables, and rendering the anchor unsuitable for future use. This procedure further inconveniences the user by requiring the availability of special tools in order to access and release the anchor chocks. If all methods of removal fail, the exposed portion of the anchor is torched off, a new hole drilled, and the balance of the anchor is left in the old hole.

[0007] A further problem of conventional anchors relates to the exposure of control cables operable for moving the anchor from the expanded condition to the contracted condition. Typically, these cables will bear directly against an inside wall of the anchor hole, resulting in substantial abrasion and chaffing when the anchor is inserted into and removed from the hole. Further wear is created when the worker moves about causing the control cables to grind against the concrete lip of the hole. If left undetected, the worn cables will eventually foul the cable motion and cause the anchor to fail which may result in inoperability, serious injury, or death.

[0008] A further problem with conventional hole anchors is the number of components required for assembly and use. Existing hole anchors require a large number of parts which disadvantageously increase the complexity and cost of manufacture. In addition, conventional hole anchors, are provided with chock cables which may kink caused by movement of the unit during normal use.

[0009] Accordingly, it would be desirable to have an improved expansible hole anchor which overcomes the noted shortcomings of conventional devices. In one such solution, it would be desirable to provide a pivot handle operable for use with an expansible hole anchor which reduces the costs of replacement units and/or components caused by having the chock cables kink or become frayed. Such a pivot handle would eliminate the possibility of kinking of the chock cables during normal use of the hole anchor.

SUMMARY OF THE INVENTION

[0010] The present invention is designed to overcome the deficiencies and shortcomings of the devices described above. The present invention is designed to reduce the costs of replacement units and/or components caused by having chock cables of the hole anchor kink or become frayed. In all exemplary embodiments, the present invention relates to an improved expansible hole anchor having a pivot handle that advantageously eliminates kinking of chock cables. The present invention is easily installed and removed from a hole formed with a solid structure. In one application, the present invention discloses a pivot handle operable for use with hole anchor that is inserted into a hole drilled in a concrete wall at a construction site. A safety harness, lifeline, and other fall protection gear is secured to the worker and to the anchor to arrest the worker in the event of a fall. In another application, the present invention is directed to a pivot handle for use with a hole anchor that is applicable for use in securing equipment, such as scaffolding, to a concrete structure, or as a lift connection point for items with a suitable hole, such as preformed concrete or boulders, or for use in recreational rock climbing.

[0011] In all exemplary embodiments, the pivot handle may be used with an expansible anchor adapted for inserting into a hole formed with a structure is provided. The hole anchor may generally include a load cable, a center chock attached to an end of said load cable, at least one, but preferably two, side chocks adjacent to said center chock and adapted for movement between an anchor-contracting position and an anchor-expanding position, whereby in said anchor-contracting position, said anchor is readily inserted into and removed from the hole of the structure, and in said anchor-expanding position, said anchor is locked inside the hole of the structure. Preferably, a chock cable is provided and interconnects the pivot handle and the at least one side chock.

[0012] According to an exemplary embodiment, the pivot handle generally includes an assembly of links and rockers movably attached together on opposite sides of the load cable by fasteners. Respective ends of chock cables may be fixed to the rockers. When assembled the rockers cooperate to allow kink-controlling movement of the chock cables relative to the load cable. The handle rocks or pivots when one chock cable is in tension and the other cable is in compression, thereby discouraging cable kinking or excessive bending which may foul effective operation of the anchor. Preferably, to facilitate retraction of the handle, finger curves are formed with the rockers.

[0013] Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0014] It is to be understood that both the foregoing general description and the following detailed description present exemplary embodiments of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention, and together with the detailed description, serve to explain the principles and operations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] These and other features, aspects and advantages of the present invention are better understood when the following detailed description of the invention is read with reference to the accompanying drawings, in which:

[0016] FIG. 1 is a perspective view of a conventional expansible hole anchor used in conjunction with an exemplary embodiment of the pivot handle of the present invention;

[0017] FIG. 2 is an exploded view of the conventional hole anchor and an exemplary embodiment of the pivot handle of FIG. 1;

[0018] FIG. 3 is a side view of the hole anchor and pivot handle of FIG. 1 with the side chocks in an anchor-expanding position;

[0019] FIG. 4 is a side view of the hole anchor and pivot handle of FIG. 1 with the side chocks in an anchor-contracting position; and

[0020] FIG. 5 is a side view of another conventional hole anchor used in conjunction with an exemplary embodiment of the pivot handle of the present invention and shown with the side chocks in an anchor-expanding position.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0021] The present invention will now be described more fully hereinafter with reference to the accompanying drawings in which exemplary embodiments of the invention are shown. However, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These exemplary embodiments are provided so that this disclosure will be both thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numbers refer to like elements throughout the various drawings. Further, as used in the description herein and throughout the claims that follow, the meaning of "a", "an", and "the" includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein and throughout the claims that follow, the meaning of "in" includes "in" and "on" unless the context clearly dictates otherwise.

[0022] The present invention overcomes the shortcomings of conventional hole anchors by providing a pivot handle about the load cable and fixed to the chock cables such that kinking of the chock cables is prevented or altogether eliminated. The use of the pivot handle reduces the overall cost associated with replacement hole anchors caused by unit failure, chock cable fraying, etc.

[0023] In exemplary embodiments of the present invention, a pivot handle for use with an expansible hole anchor is provided. As is known in the art, an expansible hole anchor may generally include a load cable having a center chock connected to one end and a loop at the opposite end, at least one side chock abutting the outer surfaces of the center chock such that they may translate between an expanded position and a retracted position, the pivot handle interconnected to the at least one side chock by at least one chock cable, a retractor spring to bias the at least one side chock in the extended position, and a chock release column having an enlarged head and being interposed between the pivot handle and the center chock.

[0024] In exemplary embodiments, the expansible hole anchor is generally operated by pulling back the pivot handle which retracts the at least one side chock, reducing the outside diameter over the combination of the center chock and the at least one side chock. The anchor is then inserted into a hole (in rock, concrete, etc.) and the pivot handle is released. Spring pressure causes the at least one side chock to translate along the center chock and expand to the hole diameter. When tension is placed upon the load cable, it pulls the center chock outward. The at least one side chock tends to remain stationary because of friction between the hole and their outer surfaces. This, in turn, results in the center chock being driven between the at least one side chock, expanding laterally and increasing the outward gripping pressure. The greater the external load placed upon the anchor, the higher the gripping pressure.

[0025] To release the anchor, the pivot handle is again retracted. This, in turn, retracts the at least one side chock to a diameter smaller than the hole. If the pivot handle is stuck in position, an enlarged head of the chock release column, exposed outside the hole, may be pushed by hand or struck with a hammer or other tool to dislodge the center chock and allow the at least one side chock to retract.

[0026] Referring now specifically to the drawings, a conventional expansible hole anchor which may be used in conjunction with a pivot handle constructed in accordance with an exemplary embodiment of the present invention is illustrated in FIG. 1, and shown generally at reference numeral 10. The hole anchor 10 is adapted for inserting into a hole formed with a solid structure, such as a concrete wall, and is applicable for use with a safety harness, lifeline, and other fall protection gear worn by a worker to arrest the worker in the event of a fall. In exemplary embodiments, the anchor 10 may comprise a load cable 11 looped at one end 12 for attaching the lifeline, and an assembly of chocks 14, 15, and 16 located at an opposite end. It will be understood by those skilled in the art that the load cable 11 may be comprised of a steel wire or any other suitable materials including but not limited to a rod or a rod like structure. The chocks 14, 15, and 16 cooperate, as described below, to constrict and expand the anchor 10 relative to the hole of the structure.

[0027] As best shown in FIGS. 1 and 2, the center chock 15 has a generally wedge-shaped body, arcuate shoulders 17 and 18, and an integrally-formed rearward extending cable connector 19. However, it will be understood by those skilled in the art that the center chock 15 may have any of a variety of shapes, including, but not limited to conical and frusto-conical. The cable connector 19 attaches the center chock 15 directly to the load cable 11. The side chocks 14 and 16 reside adjacent the center chock 15, and have complementary angled profiles designed to provide maximum uniform gripping action when set inside the structure hole. The outside surface of each side chock 14 and 16 is preferably curved to conform to an inside wall of the structure hole, while the inside surface is substantially flat for sliding along a flat outside surface of the center chock 15. In an alternative embodiment, the inside surface of each side chock is slightly convex, while the outside surfaces of the center chock are either flat or slightly concave. In yet another alternative embodiment, the hole anchor may be adapted for use with crevice gripping or climbing aids. In such an embodiment, the side chocks may be provided with outside surfaces which are planar or substantially planar in configuration to conform to an inside wall of a crevice.

[0028] The side chocks 14 and 16 are attached to respective chock cables 21 and 22. The chock cables 21, 22 extend rearward to a pivot handle 25. The pivot handle 25 is carried on the load cable 11, and is adapted for being manually retracted by the user to move the side chocks 14, 16 from a normal anchor-expanding position, best shown in FIGS. 1 and 3, to an anchor-contracting position shown in FIG. 4. In the anchor-contracting position, the side chocks 14,16 are more closely spaced apart on opposite sides of the center chock 15 and immediately forward of the arcuate shoulders 17 and 18, such that the anchor 10 is readily inserted into and removed from the hole of the structure. The spaces 26 and 27 formed between the shoulders 17 and 18 allow passage of the chock cables 21, 22 rearwardly towards the handle 25. The rear portion of the center chock 15 is relatively thin, thereby allowing substantial contraction of the anchor 10. Preferably, the thinnest section of the center chock 15 forward of the arcuate shoulders 17, 18 has a profile dimension less than the diameter of the load cable 11 (See FIGS. 3 and 4). In the anchor-expanding position, the side chocks 14, 16 are urged forward along diverging outer surfaces of the center chock 15. In use, the anchor 10 does not fully expand inside the hole, but instead forces the side chocks 14, 16 into sufficient frictional engagement with the inside wall of the structure hole to prevent inadvertent dislodging of the anchor 10. After inserting the anchor 10 into the hole, the side chocks 14, 16 are set by one controlled pull on the cable loop 12.

[0029] Referring again to FIGS. 1 and 2, a chock-release column 30 may be provided and carried on the load cable 11 adjacent the center chock 15. Such a chock release column 30 may comprise a separate cable cylinder 31 and enlarged-diameter head 32. In other embodiments, the chock release column 30 may be integrally formed with the cable cylinder 31 and the head 32. The cable cylinder 31 is positioned over the cable connector 19 of the center chock 15 and bears directly against the arcuate shoulders 17, 18. The enlarged head 32 locates outside of the structure hole, and defines a flat annular striking or bearing surface 32A designed to receive a force applied using the thumbs or any rigid object, such as a snap hook. The force is transferred directly through the chock-release column 30 to the center chock 15 to dislodge the side chocks 14, 16 from friction-locking engagement inside the hole. Once dislodged, the side chocks 14, 16 are easily retracted by the handle 25; moving from the anchor-expanding position to the anchor-contracting position to remove the anchor 10 from the structure hole. A cylindrical spacer 34 and coil spring 35 are carried on the load cable 11 rearward of the chock-release column 30, and cooperate to maintain the cable cylinder 31 and enlarged striking head 32 in an engaged, assembled condition with the cable cylinder 31 bearing directly against the shoulders 17, 18 of the center chock 15.

[0030] In exemplary embodiments, the maximum diameter of the striking head 32 is greater than the maximum distance between the side chocks 14 and 16 in the anchor-expanding condition. As such, upon insertion of the anchor 10 into the hole, the enlarged striking head 32 is pushed directly against the mouth of the hole, thereby locating the anchor chocks 14, 15, and 16 inside the hole in a position of maximum effectiveness and safety, while maintaining ready access to the exposed striking surface 32A. When the cable loop 12 is pulled vertically by the weight of the worker, the chock-release column 30 flexes slightly at a joint between the cable cylinder 31 and the enlarged head 32. The outer flange of the head 32 engages the structure outside of the hole to help distribute forces acting on the load cable 11 and the structure.

[0031] According to one embodiment, the enlarged head 32 of the chock-release column 30 has three openings for receiving the load cable 11 and chock cables 21, 22, respectively. Preferably, the center opening has a radiused edge to minimize wear on the load cable 11 when pulled vertically. A reduced diameter, integral neck 36 extends forward of the enlarged head 32 has interior passages or longitudinal exterior grooves to designed receive the chock cables 21, 22. The neck 36 cooperates with the arcuate shoulders 17, 18 to further position the side chocks 14, 16 relative to the center chock 15. The chock cables 21, 22 extend from the side chocks 14, 16, and are directed along a length of the anchor 10 by a fixed positioning block 38 located adjacent the pivot handle 25. The positioning block 38 likewise has three openings for receiving the load cable 11 and chock cables 21, 22, respectively. In order to limit twisting of the anchor 10, rotation of the chock-release column 30 relative to the center chock 15 is prevented by mating notches and fingers.

[0032] In exemplary embodiments, the pivot handle 25 generally comprises a link assembly having a plurality of links 41, 42, 43, 44 and a rocker assembly having a plurality of rockers 45, 46 (See FIG. 2) movably attached together on opposite sides of the load cable 11 by fasteners 48. As illustrated, four links are provided and movably attached to two rockers by the fasteners. However, it will be understood by those skilled in the art that any number of links may be used. By way of example, links 41, 42 and links 43, 44 may be integrally formed with each other thereby providing two unitary links, as opposed to the illustrated example of four. These two unitary links may, in turn, be movably attached to the rockers 45, 46 by the fasteners 48. Also as illustrated, the fasteners 48 are depicted as rivets, however, it will be understood by those skilled in the art that the fasteners 48 may be screws, pins, wireform(s), or the like. Respective ends of the chock cables 21, 22 are fixed to the rockers 45, 46. Advantageously, when assembled, as shown in FIGS. 1, 3, 4 and 5, the links 41, 42, 43, 44 and the rockers 45, 46 cooperate to allow kink-controlling movement of the chock cables 21, 22 relative to the load cable 11. The handle 25 rocks or pivots when one chock cable 21, 22 is in tension and the other cable 21, 22 is in compression, thereby discouraging cable kinking or excessive bending which may foul effective operation of the anchor 10. Further, the use of the pivot handle 25 in conjunction with the chock cables 21, 22 prevents and/or eliminates fraying of the chock cables 21, 22 during use.

[0033] In exemplary embodiments, the rockers 45, 46 include top and bottom surfaces 56, 57 which are substantially planar. Further, the rockers 45, 46 include a continuous side wall 58. In exemplary embodiments, finger curves 59, 60 may be formed into the side wall 58 for facilitating retraction of the handle 25. The rockers 45, 46 may also be provided with a plurality of bores 61 for receiving the fasteners 48. In other exemplary embodiments, the bores may be slots.

[0034] A washer 51 and retractor spring 52 are carried on the load cable 11 rearward of the pivot handle 25. The retractor spring 52 is compressed between the handle 25 and cable loop 12, and operates to normally urge the handle 25 and chock cables 21, 22 forward thereby biasing the side chocks 14 and 16 in the anchor-expanding position. The retractor spring 52 is preferably pre-loaded in the anchor-expanding position at greater than 20% of its maximum compression force. Preferably, the cable loop 12 is secured by a duplex ferrule 53 and reinforced with a metal thimble (not shown). An equipment tag 55 provides relevant product information.

[0035] Referring now specifically to FIG. 5, another conventional expansible hole anchor which may be used in conjunction with the pivot handle 25 constructed in accordance with an exemplary embodiment of the present invention is illustrated, and shown generally at reference numeral 100. As shown, the hole anchor 100 generally includes a load cable 112 having at a chock at a distal end thereof. A center chock 114 is provided having an outer surface 113 and a cooperating outer chock assembly 115 is provided to engage the center chock and to accommodate linear movement of the cable 112 along a longitudinal axis "L" with respect thereto. For example, the cable may be passed through the pivot handle 25 supporting the chock assembly 115.

[0036] The outer chock assembly 115 includes at least one outer chock, such as the outer chock referenced as 116, and preferably includes two or more outer chocks, such as the outer chocks referenced as 116 and 117. Each outer chock is preferably attached to the pivot handle 25 through a respective elongate control cable or rod 122 that permits moving the outer chock upwardly along the longitudinal axis with respect to the inner chock by pushing upwardly on the handle 25.

[0037] As with the foregoing conventional hole anchor 10, the pivot handle 25 may generally comprise a plurality of links 41, 42, 43, 44 and rockers 45, 46 (See FIG. 2) movably attached together on opposite sides of the load cable 112 by fasteners 48. Advantageously, when assembled about the load cable 112, the rockers 45, 46 cooperate to allow kink-controlling movement of the control cable 122 relative to the load cable 112. The handle 25 rocks or pivots when one control cable is in tension and the other cable is in compression, thereby discouraging cable kinking or excessive bending which may foul effective operation of the anchor 100.

[0038] In exemplary embodiments, the rockers 45, 46 include top and bottom surfaces 56, 57 which are substantially planar. Further, the rockers 45, 46 include a continuous side wall 58. In exemplary embodiments, finger curves 59, 60 may be formed into the side wall 58 for facilitating retraction of the handle 25. The rockers 45, 46 may also be provided with a plurality of bores 61 for receiving the fasteners 48.

[0039] The outer chocks 116 and 117 have inner surfaces 116a and 117a against which the outer surface 113 of the center chock 114 slides as a result of relative linear movement of the cable with respect to the pivot handle 25. Particularly, when the pivot handle 25 is pushed downwardly along the axis "L" in the direction of the arrow with respect to the cable, the outer chocks are forced radially outwardly, to provide an expanded configuration of the expansion bolt. When introduced into a hole, this outward expansion of the outer chocks is resisted by the inner surface of the hole, anchoring the expansion bolt in the hole. Conversely, when the handle is pulled upwardly with respect to the cable, the outer chocks are free to move inwardly toward the inner chock, or may be biased toward the inner chock by the respective control cables or rods 122, to provide a contracted configuration of the expansion bolt. This permits removing the expansion bolt from the hole.

[0040] As illustrated, FIG. 5 shows a center chock 114 having a convex outer surface 113 including convex portions 113a and 113b, along with outer chocks 116 and 117 having complementary concave inner surfaces. Preferably, the surfaces 113, 116a and 117a are each rotationally symmetric about the longitudinal axis "L," and more preferably still, the surfaces of the center and outer chocks are complementarily frustoconically shaped. An example of complementarily frustoconically shaped center and outer chocks is shown in the Figures. Here, the center chock is shaped as a frustrum so that the surface 113 is convex and the outer chock surfaces 116a and 117a are concave and substantially conform to the frustrum. The reverse geometry may also be employed for this example, wherein the surfaces 116a and 117a are convex and shaped as portions of frustrums, and the center chock surface 113 is concave and substantially conforms to these portions. Moreover, the surfaces 113, 116a and 117a may include only portions that are complementarily frustoconical where desired.

[0041] The complementarily frustoconical shapes provide a preferred means for ensuring intimate conformance between the respective ramping surfaces of the center and outer chocks over a range of relative linear movement therebetween, wherein the force exerted between the chocks is distributed over a maximum surface area. This increases reliability by decreasing stress and wear, as well as increases hole-engaging strength by permitting the aforementioned force to be maximized.

[0042] A loop 130 is provided at a proximal end of the cable 112 providing a hand-hold for a user of the expansion bolt 100, and a means for moving the cable with respect to the handle 25. A compression spring 132 is provided between the loop 130 and the handle 25, to bias the device into its expanded configuration.

[0043] The expansion bolt 100 may also provide a "cleaning bushing" 134 through which the control cables or rods 122 are slidably passed. The cleaning bushing 134 may be used to apply force to the center chock 114 to loosen the grip applied by the expansion bolt to the hole in which it is inserted, for removing the expansion bolt after use.

[0044] The embodiments described above provide advantages over conventional expansible hole anchors and associated methods of manufacture. It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. Furthermore, the foregoing description of the preferred embodiment of the invention and best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation--the invention being defined by the claims.

* * * * *


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