1. Field of the Invention
The present invention relates generally to safety devices and methods for fall protection, and more specifically, to safety devices, in an exemplary embodiment, including expansible hole anchors, operable for arresting the downward movement of a person or object after a fall.
2. Technical Background
In the construction industry, it is oftentimes 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 spring-loaded retractable handles.
A first shortcoming of conventional hole anchors is that the handle is 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's 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 disadvantageously have a striker head which may lose contact with the center chock, thus providing a defective unit. 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 an expansible hole anchor which reduces the manufacturing costs and the complexity of assembly. In other solutions, it would be desirable to provide an expansible hole anchor with a chock releasing column which is secured to a center chock, thereby ensuring continuous contact between the center chock and the striker head and decreasing side load forces which may be applied to the center chock during use.
The present invention is designed to overcome the deficiencies and shortcomings of the devices described above. The present invention is designed to reduce the manufacturing costs and the complexity of assembly. In all exemplary embodiments, the present invention relates to an improved expansible hole anchor with a chock releasing column which is advantageously secured to a center chock of the hole anchor, thereby decreasing side load forces which may be applied to the center chock during use. The present invention is easily installed and removed from a hole formed with a solid structure. In one application, the present invention discloses a 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 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.
According to an exemplary embodiment, an expansible anchor adapted for inserting into a hole formed with a structure is provided. The hole anchor generally includes 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, and a chock release column fastened to and bearing against at least one of said center chock or at least one side chock by a fastener. The chock release column generally includes an enlarged head adapted for locating outside of the hole, said enlarged head defining a striking surface adapted for receiving a sudden force and transferring the force through said chock-release column to said center chock or at least one side chock, such that said at least one side chock is movable from the anchor-expanding position to the anchor-contracting position to thereby dislodge said anchor from the hole of the structure.
In all exemplary embodiments, the chock release column is secured to the center chock such that the chock release column cannot translate or slide along the center chock and/or the load cable. The chock release column is secured to the center chock by a fastener. The fastener is preferably a pin type device. However, it may be any suitable fastening device including, but not limited to swaging, glue, rivets, screws, nails, rods, ties, or the like. In one exemplary embodiment, the fastener extends through a bore located in the chock release column and the center chock and at least partially into the load cable, thereby permitting the chock release column to pivot about the center chock, but not translate or slide along the longitudinal axis of the load cable.
In other exemplary embodiments, the fastener extends substantially through the chock release column, the cable connector and the cable load. In still other exemplary embodiments, a plurality of fasteners are employed to secure the chock release column to the center chock. Specifically, a first fastener extends through a first half of the chock release column and into the center chock. Further, a second fastener extends through an opposed half of the chock release column and into the center chock.
In still other exemplary embodiments, the center chock and the chock release column are a unitary component. The unitary component includes a tapered portion, a shaft, and an enlarged head. At least one, but preferably two, cable guides are provided about the shaft. The cable guides are preferably convexly curved plates which fit about the shaft.
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 securing a chock release column of a hole anchor device to a center chock. This method of securing the chock release column and the center chock together reduces the overall cost and the number of components required for manufacture. Further, the present invention prevents the chock release column from defectively losing contact with the center chock and provides space for an ergonomic pivot handle to be used, while shortening the overall length of the unit. Still further, the chock release column of the present invention advantageously enters into the inside of the hole during use, thus decreasing side loads which may be placed upon the center chock.
In exemplary embodiments of the present invention, an expansible hole anchor is provided which generally includes a load cable having a center chock connected to one end and a loop at the opposite end, at least one side chock movably abutting the outer surfaces of the center chock such that they may translate between an expanded position and a retracted position, a 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 all exemplary embodiments, the chock release column is secured about the load cable and bears against the center chock such that it cannot translate or slide along the longitudinal axis of load cable.
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, an expansible hole anchor constructed in accordance with an exemplary embodiment of the present invention is illustrated in
In exemplary embodiments and as best shown in
The side chocks 18 and 20 are attached to respective steel-wire chock cables 28 and 30. The chock cables 28, 30 extend rearward to a spring-loaded pivot handle 32. The pivot handle 32 is carried on the load cable 12, and is adapted for being manually retracted by the user to move the side chocks 18, 20 from a normal anchor-expanding position, best shown in
Referring again to
In exemplary embodiments, the preferable maximum diameter of the striking head 42 is greater than the maximum distance between the side chocks 18 and 20 in the anchor-expanding condition. As such, upon insertion of the anchor 10 into the hole, the enlarged striking head 42 is pushed directly against the mouth of the hole, thereby locating the anchor chocks 16, 18 and 20 inside the hole in a position of maximum effectiveness and safety, while maintaining ready access to the exposed striking surface 44.
According to one embodiment, the enlarged head 42 of the chock-release column 38 has three openings for receiving the load cable 12 and chock cables 28, 30, respectively. Preferably, the center opening has a radiused edge to minimize wear on the load cable 12 when pulled vertically. A reduced diameter, integral neck 50 extends forward of the enlarged head 42 has interior passages or longitudinal exterior grooves to designed receive the chock cables 28, 30. The neck 50 cooperates with the arcuate shoulders 22, 24 to further position the side chocks 18, 20 relative to the center chock 16. The chock cables 28, 30 extend from the side chocks 18, 20, and are directed along a length of the anchor 10 by a fixed positioning block 52 located adjacent the pivot handle 32. The positioning block 52 likewise has three openings for receiving the load cable 12 and chock cables 28, 30, respectively.
The pivot handle 32 generally comprises an assembly of links 54, 56, 58, 60 and rockers 62, 64 (See,
In another exemplary embodiment, the pivot handle 32 generally comprises an assembly of links 98, 100, 102, 104 and rockers 106, 108 (See,
A washer 72 and retractor spring 74 are carried on the load cable 12 rearward of the pivot handle 32. The retractor spring 74 is compressed between the handle 32 and cable loop 14, and operates to normally urge the handle 32 and chock cables 28, 30 forward thereby biasing the side chocks 18 and 20 in the anchor-expanding position. The retractor spring 74 is preferably pre-loaded in the anchor-expanding position at greater than 20% of its maximum compression force. Preferably, the cable loop 14 is secured by a duplex ferrule 76 and reinforced with a metal thimble (not shown). An equipment tag 78 provides relevant product information.
In all exemplary embodiments, the chock release column 38 is secured to the center chock 16 such that the chock release column 38 cannot translate or slide along the center chock 16 and/or the load cable 12. In an exemplary embodiment illustrated in
In another exemplary embodiment shown in
In still another exemplary embodiment shown in
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 claims the benefit of priority of provisional application Ser. No. 60/959,232, filed on Jul. 12, 2007, entitled EXPANSIBLE HOLE ANCHOR, the content of all the aforesaid application(s) are relied upon and incorporated by reference in its entirety.
Number | Date | Country | |
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60959232 | Jul 2007 | US |