Fire escape – ladder – or scaffold – Ladder – With hook or grab
Reexamination Certificate
2002-04-03
2004-05-04
Chin-Shue, Alvin (Department: 3634)
Fire escape, ladder, or scaffold
Ladder
With hook or grab
C182S107000
Reexamination Certificate
active
06729441
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to ladder retaining devices and, more specifically, to a ladder retaining device for extension ladders and other like ladders having side rails that extend beyond the top rung and is used to prevent the ladder from sliding and possibly falling when placed against a narrow, substantially cylindrical object such as a tree or a utility pole. When used for such applications, the top rung of the ladder is usually placed against a tree or pole with the straight rung having limited bearing surface contacting the curved surface of the object being climbed and often requires the person climbing the ladder to perform a balancing act to prevent the center of gravity from shifting to one side and creating a potentially hazardous situation.
The present invention seeks to overcome the shortcomings of the prior art by providing an extension ladder safety adapter that is fabricated from a single elongate plate of a sturdy, malleable material, preferably metal, wherein each distal end of the plate forms a substantially rectangular side rail retention bracket of a size and shape adequate to accommodate the insertion of an industry standard extension ladder side rail therethrough. Separation of the side walls of the retention bracket is prohibited by a fastening element such as a pop rivet that fastens the foot of each bracket to the bearing plate. The retention brackets are secured to the side rails either by sheet metal screws that screw directly into the ladder or by other appropriate non-penetrative pressure-securing means that may reduce damage perpetrated upon the ladder.
Once the present invention is installed and secured to the ladder it is ready for use. The extension ladder safety adapter will not obstruct the use of the ladder during conventional applications such as being placed against the flat wall of a building. When used with a tree or pole the bearing strap is placed thereagainst rather than the top ladder rung as is conventionally done. The weight of the ladder and pressure applied thereto by the user cause the bearing strap to deform to a curvature somewhat similar to that of the object supporting the ladder to create a greater bearing surface. A recess
24
is located in a central portion of the bearing strap
22
through which a fastening element
20
such as a nail or a screw may be placed and imbedded into the supporting structure to prevent the ladder from sliding and possibly falling. Furthermore, a textured, arcuate, self-centering pad
26
having a non-skid surface may be included on the supporting side of the bearing strap
22
to provide additional stability, particularly until the user climbs the ladder to install the fastening element to secure the present invention and the attached ladder to the object being climbed.
The present invention will provide a user with increased safety when using an extension ladder placed against a pole, tree or other such object by providing a ladder safety adapter comprising a malleable bearing strap having side rail retention brackets on the distal ends thereof that could be removably fastened to the side tails above the uppermost rung of an extension ladder.
2. Description of the Prior Art
There are other ladder stabilizing devices known in the art. While these ladder stabilizing devices may be suitable for the purposes for which they were designed, they would not be as suitable for the purposes of the present invention, as hereinafter described.
SUMMARY OF THE PRESENT INVENTION
The present invention discloses an extension ladder safety adapter that is fabricated from a single elongated strap made of a sturdy, malleable material, preferably metal, wherein each distal end of the strap forms a substantially rectangular side rail retention bracket of a size and shape adequate to accommodate the insertion of an industry standard extension ladder side rail therethrough. Separation of the side walls of the retention bracket is prohibited by a fastening element such as a pop rivet that fastens the foot of each bracket to the bearing strap. The retention brackets are secured to the side rails either by sheet metal screws that screw directly into the ladder side rails or by other appropriate nonpenetrative pressure-securing means that may reduce damage perpetrated upon the ladder. A recess is located in a central portion of the bearing strap through which a fastening element such as a nail or a screw may be placed and imbedded into the supporting object to prevent the ladder from sliding and possibly falling. Furthermore, a textured, arcuate, self-centering pad having a non-skid surface may be included on the supporting side of the bearing strap to provide additional stability.
A primary object of the present invention is to provide an extension ladder safety adapter that will enhance the stability of an extension ladder when placed against an object that is narrower than the distance between the side rails of said ladder.
Another object of the present invention is to provide an extension ladder safety adapter that provides a bearing plate that is removably affixed to the ladder side rails and is deformable in order to substantially conform to the object against which it is placed.
One other object of the present invention is to provide an extension ladder safety adapter that will prohibit the shifting and slipping of the ladder under conditions that would otherwise disturb the center of gravity of said ladder.
Yet another object of the present invention is to provide an extension ladder safety adapter having a means for releasably nailing or screwing the bearing strap to the support structure to temporarily secure said ladder thereto.
Another object of the present invention is to provide an extension ladder safety adapter wherein the support side of the bearing strap has a flexible, textured pad to provide a self-centering non-skid pad that also conforms to the curvature of the object being climbed to further enhance the bearing area of the support strap.
Yet another object of the present invention is to provide an extension ladder safety adapter simple and easy to use.
Additional objects of the present invention will appear as the description proceeds.
The present invention overcomes the shortcomings of the prior art by providing a malleable extension ladder safety adapter that conforms substantially to the contour of the support structure.
To the accomplishment of the above and related objects, this invention may be embodied in the form illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that changes may be made in the specific construction illustrated and described within the appended claims.
REFERENCES:
patent: 3715012 (1973-02-01), Perry
patent: 3792756 (1974-02-01), Kelly
patent: 5373913 (1994-12-01), Santos
patent: 6354400 (2002-03-01), Purkayastha
patent: 6405828 (2002-06-01), Redding
patent: 2567954 (1986-01-01), None
Chin-Shue Alvin
Kroll Michael I
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