Patent Application
20070257171
1. Field of the Invention
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.
2. Technical Background
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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:
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.
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.
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.
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.
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.
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
As best shown in
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
Referring again to
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.
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.
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
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.
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.
Referring now specifically to
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.
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
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.
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.
As illustrated,
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.
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.
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.
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.
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.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US04/24129 | Jul 2004 | US |
| Child | 11069646 | Mar 2005 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11069646 | Mar 2005 | US |
| Child | 11879135 | Jul 2007 | US |
