Patent Publication Number: US-2007114096-A1

Title: Modular ladder and tree stand system with pivoting joint

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      This invention relates to the field of ladders and tree stands. More specifically, the invention comprises a modular ladder and hunting tree stand attached together by a pivoting joint.  
      2. Description of the Related Art  
      Modular ladders designed to allow the climbing of vertical objects such as trees are disclosed in several prior U.S. patents. Examples include U.S. Pat. No. 5,040,635 to Strickland (1991); U.S. Pat. No. 6,076,634 to Simon (2000); U.S. Pat. No. 6,170,609 to Dech (2001); and U.S. Pat. No. 6,340,071 to Dickemper (2002).  
      Likewise, tree stands allowing a hunter to remain in an elevated position are widely known. Examples include U.S. Pat. No. 5,097,925 to Walker, Jr. (1992); U.S. Pat. No. 5,862,883 to Carriere (1999); and U.S. Pat. No. 6,246,000 to Johnson (2001). The present invention incorporates elements of the prior art modular ladders and tree stands. It is therefore important for the reader to have a basic understanding of these devices. Illustrations are provided in the following sections. However, the reader should bear in mind that many variations of prior art ladders and tree stands exist. The present invention can be adapted for use with virtually all of these variations. Thus, the versions shown should be viewed as a few examples among many more possibilities.  
       FIG. 1  shows a prior art climbing stick  10 . Column  12  supports a series of staggered rungs  18 . Extension  16  descends from the lower end of the column. The column&#39;s upper end opens into receiver  14 , which is sized to slidably receive an extension  16  from another climbing stick  10 . These structures allow two or more climbing sticks to be mated together to form a ladder.  
      Of course, climbing stick  10  is designed to be attached to a tree. Standoffs  20  are provided to space the column and rungs a small distance away from the tree, in order to provide clearance for the user&#39;s feet when he or she climbs the rungs.  FIG. 2  shows more detail of standoff  20 . Each end of the standoff is provided with a hole  22 . These holes allow a securing strap to be affixed to the climbing stick.  
       FIG. 3  shows the climbing stick with strap  24  affixed to its upper standoff  20 . Two straps can normally be attached to a climbing stick. However, once the climbing sticks are linked together into a ladder, one strap per stick is usually sufficient.  FIG. 4  shows more detail of strap  24 . Each end of the strap is provided with a hook  26  which passes through a hole  22  on the standoff. Adjustment clasp  28  allows the strap to be tightened and secured. Those skilled in the art will know that many different strap and strap securing devices are used—including chains, cables, etc.  
       FIG. 5  shows a climbing stick  10  affixed to tree  30  by strap  24 . The reader will observe that the ends of the two standoffs are drawn tightly against the tree.  FIG. 6  shows one type of prior art tree stand  32 . It has features common to many tree stands. A seat  38  is joined to a foot rest  34  by an upright  36 . For this particular version, foot rest  34  is pivotally attached to upright  36  so that it can be folded. A pair of cables  40  support and stabilize the foot rest when it is folded down into the position shown.  
      The stand shown is a folding “cam” type, the operation of which is illustrated in  FIGS. 7 through 9 . In  FIG. 7 , foot rest  34  is folded upward toward upright  36 .  FIG. 8  shows the stand placed against tree  30 . Strap  24  is secured to the tree stand and drawn fairly tight while pads  42  and upper jaw  44  rest against the tree. The user then forces the foot rest downward in the direction indicated by the arrow.  FIG. 9  shows the result. The foot rest has rotated to a horizontal orientation and drawn its supporting cables taut. Pads  42  have been forced hard against the tree. The lower portion of the upright has been rotated outward. These motions create a camming over center effect. Those skilled in the art will realize that strap  24  will be significantly tightened. The result is that the tree stand is held very tightly against the tree, creating a stable platform.  
      However, the camming motion shown in  FIGS. 8 and 9  creates a challenge for the present invention. The combined rotation and translation of the tree stand components must be taken into account when attaching this type of stand to another device, as will be explained subsequently.  
       FIG. 10  shows the prior art tree stand and climbing sticks in use. Four climbing sticks  10  have been linked together and affixed to tree  30  using a series of straps  24 . The user then climbs the linked sticks carrying the tree stand. Tree stand  32  is then affixed to the tree above the top of the ladder formed by the climbing sticks.  
      In some instances, the tree stand may be attached to the top of the climbing sticks so that the sticks and the stand can be rotated up and against the tree as one unit. U.S. Pat. No. 6,719,093 to Garbs (2004) shows such a device. The position of the ladder and the stand are much the same as shown in  FIG. 10 , however.  
      The user must climb the ladder formed by the linked climbing sticks, then climb around and onto the tree stand. This action represents an obvious hazard. It would be advantageous to provide a ladder and tree stand system which allows an easier transition from the ladder to the tree stand.  
     BRIEF SUMMARY OF THE INVENTION  
      The present invention comprises a portable modular ladder and tree stand which can be attached to a vertical object to be climbed—such as a tree. The ladder&#39;s structure is preferably provided by two or more vertical climbing sticks locked together. These climbing sticks can be secured to the object to be climbed by a securing strap or other conventional means. A set of rungs extend outward from the climbing sticks.  
      The invention also includes a pivoting connection between a climbing stick and a tree stand attached thereto. A set of climbing sticks and associated tree stand can be assembled on the ground and then rotated up against a tree. The pivoting connection allows a user to rotate the tree stand away from the climbing sticks before attaching the tree stand to the tree. A second embodiment includes a swing link and two pivot joints in order to accommodate the complex motion of a camming tree stand. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       FIG. 1  is a perspective view, showing a prior art climbing stick.  
       FIG. 2  is a detail view, showing certain features of a prior art climbing stick.  
       FIG. 3  is a perspective view, showing a strap attached to the climbing stick.  
       FIG. 4  is a detail view, showing how the strap attaches to the climbing stick.  
       FIG. 5  is a perspective view, showing a climbing stick attached to a tree.  
       FIG. 6  is a perspective view, showing a prior art tree stand.  
       FIG. 7  is a perspective view, showing the tree stand of  FIG. 6  in a folded state.  
       FIG. 8  is a perspective view, showing how a camming tree stand attaches to a tree.  
       FIG. 9  is a perspective view, showing a camming tree stand attached to a tree.  
       FIG. 10  is a perspective view, showing a typical installation of a prior art modular ladder and tree stand.  
       FIG. 11  is a perspective view, showing a climbing stick modified according to the present invention.  
       FIG. 12  is a detail view, showing a receiver added to a climbing stick.  
       FIG. 13  is a perspective view, showing a tree stand modified according to the present invention.  
       FIG. 14  is an exploded perspective view, showing a pivotal attachment between a climbing stick and a tree stand.  
       FIG. 15  is a perspective view, showing the components of  FIG. 14  in an assembled state.  
       FIG. 15B  is a detail view, showing the use of a locking pin to secure the pivot joint.  
       FIG. 16  is a perspective view, showing a tree stand assembly.  
       FIG. 17  is a perspective view, showing the tree stand assembly being rotated up against a tree.  
       FIG. 18  is a perspective view, showing a tree stand pivotally attached to a modified climbing stick.  
       FIG. 19  is a perspective view, showing a tree stand pivoting away from a modified climbing stick.  
       FIG. 20  is a detail view, showing how a separate receiver can be attached to a prior art climbing stick.  
       FIG. 21  is a perspective view, showing the addition of a swing link to create two pivot joints.  
       FIG. 22  is a detail view, showing the swing link and associated components.  
       FIG. 23  is a perspective view, showing the operation of the swing link with a camming tree stand.  
       FIG. 24  is a perspective view, showing the operation of the swing link with a camming tree stand. 
    
    
     REFERENCE NUMERALS IN THE DRAWINGS  
     
         
         
           
               10  climbing stick  
               12  column  
               14  receiver  
               16  extension  
               18  rung  
               20  standoff  
               22  hole  
               24  strap  
               26  hook  
               28  adjustment clasp  
               30  tree  
               32  tree stand  
               34  foot rest  
               36  upright  
               38  seat  
               40  cable  
               42  pad  
               44  upper jaw  
               45  cylinder  
               46  modified climbing stick  
               48  receiver  
               50  extension  
               52  mounting arm  
               54  pivot joint  
               58  tree stand assembly  
               60  receiver mount  
               62  bracket  
               64  fastener  
               65  swing link  
               66  extension  
               68  extension  
               70  hole  
               78  hole  
               80  first pivot joint  
               84  second pivot joint  
           
         
       
    
     DESCRIPTION OF THE INVENTION  
      FIG. 11 shows a prior art climbing stick modified according to the present invention. The device is designated as modified climbing stick  46 . Cylinder  45  has been added to the upper standoff  20 . This cylinder opens into a hollow receiver  48 .  FIG. 12  shows a detailed view of cylinder  45  and receiver  48 . Hole  22  has been slightly relocated in order to accommodate the cylinder.  
       FIG. 13  shows the corresponding modification to a tree stand. Mounting arm  52  has been attached the footplate. It includes a descending extension  50 .  FIG. 14  shows how extension  50  slips inside receiver  48 , thereby forming a pivot joint. The reader should note that mounting arm  52  and extension  50  could be attached to a prior art tree stand at many different points and by many different methods (such as welding, mechanical fasteners, a clamping bracket, etc.). Likewise, receiver  48  could be attached to a prior art climbing stick at many different points and many different methods. The embodiment shown is only one example among many.  
       FIG. 15  shows extension  50  securely placed within receiver  48 , thereby forming pivot joint  54 . Tree stand  32  is pivotally connected to modified climbing stick  46 . It is free to pivot in the direction indicated by the arrows.  FIG. 15B  shows a closer view of the pivot joint. Extension  50  is preferably made long enough to extend out the bottom of cylinder  45 . A transverse hole through the extension can then be provided. If the user wishes to lock the tree stand and ladder together, he or she places locking pin  56  through this transverse hole. This securely locks the tree stand and ladder together—even if the assembly is inverted. By removing the locking pin, the user can disassemble the pivot joint in order to separately transport and store the components. Other retaining devices can be substituted for the locking pin, such as a transverse bolt, a lanyard, or a mechanical toggle.  
       FIGS. 16-19  illustrate the assembly and installation of the integrated ladder and tree stand. The devices are preferably assembled on the ground. Two or more climbing sticks are assembled together, with the number of climbing sticks being determined by the height desired. Modified climbing stick  46  is placed near what will become the top of the ladder. Tree stand  32  is then attached to modified climbing stick  46  by pivot joint  54 . The completed assembly is designated as tree stand assembly  58 .  
       FIG. 17  shows tree stand assembly  58  being erected against a tree  30 . All the components used are preferably made of a light material—such as aluminum—so that the weight of the assembly remains manageable. The assembly is erected by the user grasping its lower end and pivoting it upward as shown. The user then secures one of the lower climbing sticks to the tree using a securing strap (as for the prior art).  
      Next, the user climbs the linked climbing sticks, adding additional securing straps as appropriate. Those skilled in the art will know that the user will preferably wear a safety harness attached around the tree.  FIG. 18  shows the top of the ladder, after the user has added appropriate straps  24  to secure the ladder to the tree. At this point the reader will observe that the prior art concern of the tree stand lying over the top of the ladder remains. However, thanks to pivot joint  54 , the user simply reaches up and pivots the tree stand off to the side as indicated by the arrow.  
       FIG. 19  shows tree stand  32  pivoted away from the top of the ladder and against tree  30 . An additional strap  24  can then be added to secure tree stand  32  to tree  30 . Those skilled in the art will realize that the result is a mechanically stable assembly. The user can climb to the top of the ladder and then step laterally onto the three stand. If desired, another climbing stick can be attached to the top of modified climbing stick  46  in order to provide extra rungs to grip during the transfer to the tree stand. In other words, pivot joint  54  need not be located near the very top of the ladder.  
      Having thus gained an understanding of the pivot joint and its attachment to the tree stand, the reader will appreciate that the pivot joint itself can be created using virtually endless combinations of mechanical devices.  FIG. 20  shows one such variation. Rather than attaching cylinder  45  to one of the standoffs, a separate receiver mount  60  has been provided. It can be welded to the climbing stick. Alternatively, it can be attached using a bracket  62  and mechanical fasteners  64  (Such a bracket can obviously be used to provide a receiver on an unmodified, prior art climbing stick). Many other attachment means are known to those skilled in the art.  
      Of course, the simple pivot joint shown in  FIGS. 11-19  may not work well for camming tree stands. As described previously, a camming stand tends to translate away from the tree when the foot rest is forced downward. An accommodation for this translation is preferable.  FIGS. 21 through 24  show such an accommodation.  
       FIG. 21  shows a climbing stick with a receiver mount  60  and receiver  48  added. Swing link  65  is added to create a dual pivot joint arrangement.  FIG. 22  shows swing link  65  is more detail. It has two ends joined by arm  82 . The first end mounts a descending extension  66  sized to rotatably fit within receiver  48 . The second end includes an ascending extension  68  sized to rotatably fit within hole  78  on the tree stand. For this particular version, hole  78  is located in upper jaw  44  of the tree stand. Hole  78  can, of course, be located on many different portions of the tree stand. Hole  70  is provided in extension  66 , while hole  76  is provided in extension  68 . Locking pins can be placed in these holes to lock the pivot joints together.  
       FIG. 23  shows the device in an assembled state. The inclusion of the swing link creates first pivot joint  80  and second pivot joint  84 . In the position shown, the camming tree stand&#39;s securing strap is put in place. Foot rest  34  is then forced downward.  FIG. 24  shows the camming stand locked in place. Swing link  65  has rotated slightly outward—away from the tree. Its presence, along with the two pivot joints, has allowed the translating motion needed to accommodate the camming stand. Second pivot joint  84  is also preferably made a bit “sloppy” (extension  68  is made a bit smaller than hole  78 ) in order to allow the stand to pitch upward slightly during the camming motion.  
      Although the preceding description contains significant detail, it should not be construed as limiting the scope of the invention but rather as providing illustrations of the preferred embodiment of the invention. Thus, the scope of the invention should be fixed by the following claims, rather than by the examples given.