Abstract:
A tree stand with adjusting features allowing it to remain level in use. The invention includes two main subassemblies—a lower foot platform and an upper seat platform. The foot platform features a pivotally attached foot rest portion which can be adjusted in pitch. The seat platform includes a rotating seat with a pitch pivot located underneath. The seat&#39;s pitch is infinitely adjustable without affecting its rotation about the yaw axis. The seat platform also includes two telescoping climbing arms which the user can grasp when moving the two platforms up a tree. These climbing arms can be stowed once the stand is in position for use.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention.  
         [0002]     This invention relates to the field of tree stands. More specifically, the invention comprises a tree stand incorporating adjustment features allowing it to assume a level attitude when attached to a sloping object.  
         [0003]     2. Description of the Related Art.  
         [0004]     Tree stands have been in common use for many years. Some of these stands are made as a separate footrest assembly and seat assembly. These two separate assemblies can then be progressively moved up the trunk of a tree to “climb” the stand into position. One such prior art climbing stand is shown in U.S. Pat. No. 5,996,738 to Nelsen (1999).  FIGS. 2A and 2B  of the Nelsen disclosure illustrate the conventional use of a climbing tree stand. The Nelsen disclosure is hereby incorporated by reference.  
         [0005]     The Nelsen disclosure also illustrates a conventional method for affixing the stand components to a tree trunk. Nelsen&#39;s  FIG. 1  shows how each assembly includes a horizontal platform butted against the tree. A loop (element (6) in the view) is then passed around the tree at an acute angle to the horizontal platform. Those skilled in the art will realize that weight placed on the horizontal platform will tend to lock the assembly to the tree. By the same token, if the horizontal platform is lifted upward, the assembly can freely slide up the trunk. Thus, a user standing on the lower platform can use his or her arms to push the upper platform upward. The user can then grasp the upper platform, hook his or her feet in the lower platform, and pull the lower platform upward. These cycles are repeated to work the two platforms up the tree.  
         [0006]     The loop around the tree (element (6)) must be substantially inelastic. If the tree diameter changes, the length of the loop must be adjusted in order to keep the platform horizontal. Of course, the diameter of most trees tapers going upward. It is generally impractical to constantly adjust the length of the loops while climbing. The platforms may therefore tend to pitch downward as the tree is climbed.  
       BRIEF SUMMARY OF THE PRESENT INVENTION  
       [0007]     The present invention comprises a tree stand with adjusting features allowing it to remain level in use. The invention includes two main subassemblies—a lower foot platform and an upper seat platform. The foot platform features a pivotally attached foot rest portion which can be adjusted in pitch. The seat platform includes a rotating seat with a pitch pivot located underneath. The seat&#39;s pitch is infinitely adjustable without affecting its rotation about the yaw axis. The seat platform also includes two telescoping climbing arms which the user can grasp when moving the two platforms up a tree. These climbing arms can be stowed once the stand is in position for use. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0008]      FIG. 1  is an exploded perspective view, showing the foot platform.  
         [0009]      FIG. 2  is a perspective view, showing the foot platform in an assembled state.  
         [0010]      FIG. 3  is a perspective view, showing the foot platform attached to a tree.  
         [0011]      FIG. 4  is a detail view, showing the pivoting foot rest.  
         [0012]      FIG. 5  is an exploded perspective view, showing the chair platform.  
         [0013]      FIG. 6  is a perspective view, showing the chair platform in an assembled state.  
         [0014]      FIG. 7  is a perspective view, showing the chair platform from underneath.  
         [0015]      FIG. 8  is a detail view, showing the pitch adjustment mechanism of the seat.  
         [0016]      FIG. 9  is a perspective view, showing the foot platform and chair platform attached to a tree.  
         [0017]      FIG. 10  is a perspective view, showing how the two climbing arms can be stowed.  
         [0018]      FIG. 11  is a perspective view, showing the two platforms in position on a tree.  
         [0019]      FIG. 12  is a perspective view, showing the pitch adjustment of the seat.  
         [0020]      FIG. 13  is a perspective view, showing the stand in a pitch-adjusted configuration and ready for use.  
                                                 REFERENCE NUMERALS IN THE DRAWINGS                                10   foot platform   12   foot platform frame       14   pivot joint   16   foot rest       18   cable guide   20   tube end       24   pivot tube   26   strut       28   fixed eye   30   lower cable       32   serrated plate   34   tree       36   adjustment plate   38   adjustment hole       40   locking pin   42   seat platform frame       44   hollow receiver   46   climbing arm       48   toe loop   50   seat tube       52   seat platform   54   upper cable       56   pitch pivot   58   yaw pivot       60   seat   62   rod anchor       64   pitch rod   66   pitch wheel       68   threaded hole   70   swivel block       72   swivel block pin   74   swivel block mount       80   toe loop                    
     
    
     DESCRIPTION OF THE INVENTION  
       [0021]      FIG. 1  shows foot platform  10  in an exploded view. Foot platform frame  12  is intended to remain approximately horizontal. It is formed from a series of tubes welded together to form a space frame. One side of the frame is designed to bear against a tree trunk. This side features arc  48 , which is an arcuate piece of tubing having a diameter which is preferably larger than the diameter of a typical tree trunk. Two serrated plates  32  are mounted on arc  48  facing the tree. These frictionally engage tree trunk to hold the foot platform in position.  
         [0022]     Two tube ends  20  flank arc  48 . A pivot tube  24  slides over and rotatably mounts on each pivot tube  24  is connected to a cable guide  18  by a strut  26 . Each pivot tube  24 , strut  26 , and cable guide  18  are rigidly locked together, so that they rotate in unison about a tube end  20 .  
         [0023]     Foot rest  16  is pivotally attached to foot platform frame  12  on the opposite side from arc  48 . Foot rest  16  can be pivotally adjusted with respect to foot platform frame  12 .  FIG. 2  shows foot platform  10  in an assembled state. Each cable guide  18  has been attached by placing its respective pivot tube  24  over the respective tube end  20 . These can be retained in place by a mechanical stop or similar device. Lower cable  30  is passed through the hollow interior of both cable guides  18  to form a loop lying above arc  48 . The two free ends of the cable are attached to foot platform frame  12  near the point where foot rest  16  is attached. One or both of the cable attachments are made removable so that the device can be removed from a tree. One or more of the cable attachments is also made adjustable so that the overall length of the cable can be adjusted.  
         [0024]      FIG. 3  shows foot platform  10  attached to tree  34 . The reader will observe how lower cable  30  is passed around the tree&#39;s trunk. The weight of the foot platform causes the two serrated plates  32  to bear against the tree and hold the assembly in position. Those skilled in the art will know that additional weight placed on foot platform frame  12  (such as by the user standing on it) will serve to increase the normal force against the tree produced by the two serrated plates. However, those skilled in the art will also know if a user lifts up the foot platform, it will be free to slide up the tree trunk.  
         [0025]     Still looking at  FIG. 3 , the advantage of pivotally mounting the two cable guides to the foot platform will be explained. The platform must be able to function with trees of varying diameter. The total length of the cable can be adjusted for this purpose, so that it forms a larger or smaller loop. In the case of a smaller loop, the two struts will pivot inward to position the two cable guides further inward. This repositioning prevents the cable tension from placing a large inward force on the top of the struts, which might bend them. Thus, the combination of the pivoting cable guide assemblies and the adjustable length of the cable allows the user to apply the foot platform to trees having different diameters.  
         [0026]      FIG. 4  is a detail view of foot rest  16  and the features attaching it to foot platform frame  12 . Foot rest  16  is pivotally attached to the foot platform frame by a pair of pivot joints  14 . These pivot joints allow the pitch of the foot rest to be adjusted with respect to the pitch of the foot platform frame. A pair of adjustment plates  36  are provided, with one plate being located on each side of the foot platform frame proximate a pivot joint  14 . Each adjustment plate  36  includes a series of adjustment holes  38  located along an arc.  
         [0027]     A locking pin  40  can be passed through a desired hole and underneath foot rest  16  to support it at a desired pitch. The locking pin can be equipped with a ball detent or other retaining feature so that it does not accidentally slip out of an adjustment hole. It can also be tied to the foot platform by a small flexible cable so that it will not be lost. A locking pin is preferably provided for both sides of the foot rest. Thus, by placing the locking pins in the appropriate adjustment holes, the user can set the pitch of the foot rest.  
         [0028]      FIG. 5  shows an exploded view of seat platform  52 . Its structure is generally similar to the foot platform. Seat platform frame  42  is composed of tubes welded together. Like the foot platform frame, it includes an arc  48  with serrated plates  32 . These features are positioned to bear against the tree. Two cable guides, with associated struts  26  and pivot tubes  24  are pivotally attached to seat platform frame  42 .  
         [0029]     Seat tube  50  is located near the end of the seat platform which is furthest from the tree. It mounts an adjustable seat, which will be described subsequently. The two tubes defining the sides of the seat platform frames each end in a hollow receiver  4  which is sized to receive a climbing arm  46 . These two climbing arms  46  slide out of the hollow receivers to an extended position. They are prevented from coming all the way out of the seat platform frame by mechanical stops.  
         [0030]      FIG. 6  shows seat platform  52  in an assembled state, with the two climbing arms  46  in the extended position. The two cable guides  18  are pivotally attached to the side of the seat platform frame facing the tree. Upper cable  54  is installed through the hollow interiors of the two cable guides and adjustably attached to the seat platform frame. As for the foot platform, the length of the upper cable is made adjustable to accommodate different tree diameters.  
         [0031]      FIG. 7  shows the same assembly from underneath. The reader will observe that seat  60  has been attached to seat tube  50 . It is actually attached through two rotational joints—yaw pivot  58  and pitch pivot  56 . Yaw pivot  58  allows the seat to swivel freely about the yaw axis. Pitch pivot  56  allows the pitch of the seat to be adjusted with respect to the seat platform frame.  
         [0032]     The pitch is adjusted by turning pitch wheel  66 . The user can perform this adjustment while seated. Pitch rod  64  is a long threaded rod. The end of the rod nearest the tree is rotatably mounted to rod anchor  62 . Rod anchor  62  allows the end of the pitch rod it contains to turn freely, but not to move in or out of the rod anchor.  
         [0033]      FIG. 8  shows pitch pivot  56  in more detail. Swivel block  70  is pivotally mounted by two swivel block pins  72  to the two swivel block mounts  74  (one on either side of the pitch wheel). This feature allows the swivel block to pivot with respect to the two swivel block mounts. The reader will observe that the two swivel block mounts  74  are rigidly connected to pitch pivot  56 .  
         [0034]     Threaded hole  68  passes through the center of swivel block  70 . This thread is designed to engage the external threads on threaded rod  68 . Those skilled in the art will thereby realize that if the user turns the pitch wheel in a clockwise direction swivel block  70  will be forced further away from rod anchor  62 , with the result that pitch pivot  56  will pitch the seat upward. If the user turns the pitch wheel in a counterclockwise direction, the swivel block will be forced closer to the rod anchor and the pitch pivot will pitch the seat downward. Thus, by turning the pitch wheel, the user can set the pitch of the seat with respect to the seat platform frame. Once the user stops turning the pitch wheel, the chair will tend to remain in the pitch set without requiring a supplemental locking means.  
         [0035]     The operation of the invention will now be described in detail.  FIG. 9  shows the invention installed on tree  34 . Foot platform  10  is attached via the lower cable and seat platform  52  is attached via the upper cable. The two climbing arms  46  are shown in the extended position—ready for climbing. The user stands on the foot platform with his or her body being located between the two climbing arms. The user then lifts the seat platform up a foot or so, where it again grabs the tree and comes to rest.  
         [0036]     Next, the user hooks his or her toes under toe loop  48  while grasping the two climbing arms. The user then pulls the foot platform up a foot or two, where it grabs the tree and comes to rest. The user is then ready to push the seat platform up another step, whereupon the cycle repeats. Many types of toe loop devices are known. The one depicted is merely a simplified representation. Those skilled in the art will know that the toe loop is merely a convenience. Some users may simply hook their feet under the frame itself to pull up the foot platform.  
         [0037]     The steps described are repeated until the stand has reached a desired height on the tree. The diameter of the tree has generally tapered somewhat by this point.  FIG. 10  shows the result. The user generally does not have time to continually adjust the cable lengths while climbing the tree. Thus, by the time the stand is suspended high off the ground, the cable lengths are too long to keep the platforms horizontal. By this point they will slope downward as shown in  FIG. 10 .  
         [0038]     The user therefore needs to adjust the stand for use. First, the user pushes the two climbing arms  46  back into the two hollow receivers. Mechanical detents can be provided to keep the climbing arms in this position. If a fairly close fit is used, friction alone will be sufficient to hold them in position. With the climbing arms stowed, the user can then sit on the seat. However, as shown, the user will be uncomfortably pitched forward.  
         [0039]     In  FIG. 11 , the user has adjusted the pitch of foot rest  16  upward and locked it in position. In  FIG. 12 , the user begins turning pitch wheel  66  in a clockwise position in order to pitch seat  60  upward with respect to the seat frame.  FIG. 13  shows the seat after the pitch has been adjusted to the horizontal. The stand is now ready to use. The hunter can swivel on seat  60  while maintaining his or her feet braced against foot rest  16 .  
         [0040]     Although the preceding description contains significant detail, it should not be viewed as limiting the invention but rather as providing examples of the preferred embodiments. Accordingly, the scope of the invention should be fixed by the following claims rather than by any examples given.