Fire escape – ladder – or scaffold – Wall- or floor-attached – Single pole or strand
Reexamination Certificate
1999-05-20
2003-04-15
Stodola, Daniel P. (Department: 3634)
Fire escape, ladder, or scaffold
Wall- or floor-attached
Single pole or strand
C182S093000
Reexamination Certificate
active
06547035
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to ladders for outdoor use, and more specifically to modular ladders used for climbing trees.
BACKGROUND OF THE INVENTION
In order to hunt wild game such as deer and bears, many hunters find it desirable to place themselves in an elevated position above the animal hunted to prevent detection of the hunter by the animal. To do so, many hunters utilize tree stands that position the hunter in a tree a number of feet above the ground, keeping the hunter out of the typical line of sight of the animal.
As these tree stands are designed to position the hunter in a tree a number of feet above the ground, the problem arises of how the hunter will be able to place both the tree stand and himself in the tree at sufficient distance above the ground. In most cases, an individual will use some type of ladder to reach the portion of the tree on which the tree stand is to be placed. To accommodate the needs of the individual utilizing the ladder, the ladders designed for this purpose should optimally be lightweight, durable,: and easily portable.
The simplest type of ladder that may be used for this purpose is a conventional stepladder, consisting of a pair of parallel rails separated by a number of steps or rungs attached between the rails. The stepladder can be leaned against or placed adjacent a selected tree to allow the individual to secure the hunting stand at the desired level on the tree. However, these conventional stepladders present certain problems when used for this purpose. Due to the size of most stepladders, they become unwieldy when transported into the normally confined environment of a forest where a tree stand is used. Also, the stepladder is not equipped with any type of safety device that reliably secures the stepladder to the tree. Without such a device, there is no way to prevent the ladder from inadvertently sliding off of the tree and injuring an individual using the ladder.
Other types of ladders have been specially designed for use in connection with hunting tree stands to overcome the problems associated with utilizing a conventional ladder. One type of ladder designed specifically for this purpose is disclosed in McSwain U.S. Pat. No. 3,336,999. This combination ladder and hunting stand includes a stand or platform upon which the hunter may sit while hunting, a ladder assembly extending downwardly from one side of the stand to support the stand above the ground, and a clamp mechanism attached beneath the stand opposite ladder assembly for securing the stand and ladder assembly to the trunk of a tree. The ladder assembly is comprised of a number of intermediate ladder sections that are detachable from one another, allowing the ladder assembly to be quickly taken down and placed into a compact, portable arrangement.
While this invention provides a ladder and hunting stand capable of being reliably secured to a tree trunk by the clamp mechanism, the ladder assembly forms a conventional stepladder-like arrangement when assembled. As such, the hunting stand still has problems similar to those associated with a conventional stepladder. For instance, the clamping mechanism will only properly grip the tree when the ladder assembly is placed at an angle commensurate with the tree trunk. When an irregularly shaped tree trunk is not close to perpendicular to the ground at the point at which the clamping mechanism is attached to the tree, the ladder assembly is not able to be positioned perpendicularly to the ground to insure a stable base for the ladder assembly. Therefore, the assembly cannot be utilized with a tree having a trunk that is irregularly shaped. This necessarily limits the number of trees on which the hunting stand disclosed in McSwain may be used. Furthermore, as the ladder assembly is a single, unitary piece when constructed, any limbs or branches extending outwardly from the lower portion of the trunk may also create problems by contacting the assembly and preventing the proper stable positioning of the assembly adjacent the selected tree.
Other types of ladders have been developed for climbing trees that utilize a modular construction that allows the ladders to be utilized with trees having irregularly shaped trunks and/or branches extending from the trunk at a low level, conditions which make ladders having conventional stepladder arrangement unusable.
The individual modules, or climbing sticks, used in forming these ladders have a simple construction comprised of a number of individual alternating steps secured to an elongate tubular support member. The individual steps are pivotably mounted to the support member, allowing the steps to rotate from a closed, vertical position when the module is in transport or is not in use, to an open, horizontal position where the step points outward perpendicular to the support member to provide alternating stepping surfaces for the individual utilizing the module ladder.
Each module is secured to the tree trunk by a securing belt permanently attached at one end by a bolt to one side of the support member. The belt is releasably secured at its opposite end to a belt hook permanently attached to the support member opposite the belt.
The module is supported on the tree by a pair of stabilizing brackets located at the upper and lower ends of the support member. The brackets engage the trunk of the tree to prevent the ladder module from sliding downwardly along the trunk while supporting an individual. The brackets are rotatably mounted to each end of the support member to allow each bracket to independently conform to the direction in which the tree trunk extends.
However, these individual ladder modules still have certain shortcomings. First, the steps each have a stepping surface on only one side of the step. Therefore, in order to laterally position the step to expose the stepping surface, the step must be rotated in a specified direction relative to the support member to present the stepping surface. Due to the location of branches on the trunk of a tree, it may not be possible to rotate one or more of the steps on the support member in the required direction to properly expose the stepping surface as a branch may prevent the complete rotation of the step in that direction.
Similarly, when securing the ladder module to the tree, the permanent attachment of the securing belt at one end to the support member necessitates the securing of the belt to the support member around the tree trunk in only one direction. Again, due to the placement of branches on the trunk of the tree, it may not be possible to properly secure the securing belt around the tree trunk due to interference from the branches.
Lastly, the construction of the individual ladder modules, while being is lightweight and allowing for easy transportation of each modules, does not include any convenient way for connecting individual modules together to form a convenient and portable nested ladder module arrangement.
SUMMARY OF THE INVENTION
The present invention is an improved ladder module, or climbing stick, used by individuals to form a modular ladder for climbing a tree to position and/or reach a tree stand. The module is formed similarly to prior art ladder modules and comprises a set of steps rotatably connected to an elongate tubular support member. The steps have an arrowhead shape and are spaced from each other along the length of the support member to form an upper step, a middle step, and a lower step. Each step includes a grooved stepping surface disposed on both long sides of each step that allow the steps to provide a non-slip stepping surface when rotated to either side of the support member. Also, on both sides of the point of attachment of each step to the support member are located a pair of annular shoulders, capable of restricting the rotation of each step with respect to the support member. Each shoulder engages a stop located beneath the step to selectively position the step outwardly on either side of the support member. This improved step construction allows the ladder module of t
Boyle Fredrickson Newholm Stein & Gratz S.C.
Stodola Daniel P.
Thompson Hugh B.
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