Abstract:
Disclosed is an improved apparatus for engaging and climbing columnar structures such as trees and poles that includes improved structural support members and an improved foot climber assembly. The size and shape of the structural components have been optimized for strength and portability. The improved tree-gripping surfaces have a curved shape, an increased thickness, and a series of substantially parallel ridges along the outer surface for stronger and more stable gripping ability. Softer stops and tighter locks are provided between components for quiet assembly and operation in sensitive habitats. The geometry of the apparatus positions the hunter&#39;s weight to maintain a strong and safe tree-gripping lever action in order to prevent the apparatus from slipping down the tree. The flexible seat permits the user to remain safe, comfortable, and motionless for long periods. The user can climb and descend the tree with the assistance of the apparatus.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit and priority of the pending Provisional Patent Application entitled, “Tree Support for Hunters, Improved for Optimal Climbing and Portability,” Application Serial No. 60/266,349, filed Feb. 2, 2001, which is incorporated herein by reference, together with all attachments and exhibits thereto. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to the field of climbing and support devices for use on columnar structures such as trees, poles, and the like. More particularly, the invention includes an improved tree stand and climbing apparatus consisting of two frames with gripping cleats which are alternately raised by the user to climb a tree or pole and then sit comfortably at a desired elevation.  
         BACKGROUND OF THE INVENTION  
         [0003]    It has been recognized that an advantage is obtained in hunting by occupying a position above the ground and by preventing wild game such as deer from sensing any motion of a hunter. Such a position avoids the deer&#39;s vision, sense of smell, and highly developed ability to detect motion. The problem of avoiding discovery by deer was approached by constructing permanent tree stands or blinds, with the obvious disadvantage that the hunter was confined to a single location. Also, attempts were made to provide portable platforms for temporary mounting in trees at an appropriate height. Some such portable devices must be strapped to the tree trunk, and access is gained to them by attaching a portable ladder device to the tree. One such device is shown in U.S. Pat. No. 3,116,808. Installation of such a device is complicated and time consuming, and its several components are not conveniently carried about from tree to tree. Furthermore, the devices are potentially unsafe because of the unsure nature of the attachment of the platform to the tree.  
           [0004]    Various two-part tree and pole climbing devices, including deer stands and shooting platforms, are known in the art. Typical devices include a lower frame maneuvered by the climber&#39;s feet and an upper frame that includes a platform for sitting when the desired height is reached. For example, U.S. Pat. No. 4,726,447 to Gibson, et al., discloses a two-part device with spikes for gripping the tree surface. U.S. Pat. No. 4,834,217 to Manes discloses a two-part device with spring-actuated locking bolts for adjustment. Other two-part devices include a multitude of hinges, pins, and adjustable platforms such as those disclosed in U.S. Pat. No. 5,156,236 to Gardner, et al., U.S. Pat. No. 5,167,298 to Porter, and U.S. Pat. No. 5,316,104 to Amacker.  
           [0005]    An example of a two-part device where the seat is part of the lower frame is disclosed in U.S. Pat. No. 3,856,111 to Baker. The device includes a horizontal platform intended to bite into the tree at the inner edge thereof, and an angularly-disposed frame that extends upwardly from the outer edge of the platform around the tree at a position above the platform. The weight of the person on the platform is intended to create a lever action to hold the device on the tree trunk. However, such devices have been known to fall out of trees with persons on them because they are not designed to use the weight of the person to maximum advantage in causing the device to bite into the tree. Also, the platform provided is small and hard, and therefore a person standing or sitting thereon soon becomes restless and cannot remain motionless. This lack of comfort is critical because once the hunter begins to move even slightly, the advantage of his elevated position will be largely lost.  
           [0006]    These problems were largely solved by the commonly-owned invention described in U.S. Pat. No. 4,337,844 to Hice, Sr., which is incorporated herein by reference. Instead of a separate frame maneuvered by the feet, the apparatus disclosed in Hice included spaces for the user to insert his feet and lift the apparatus while grasping the tree with his arms.  
           [0007]    Many of the prior art climbing platforms suffer from the disability of being too heavy for most users, especially hunters who often must travel long distances on foot to reach the habitat of the wild game being sought. Other, lighter-weight devices are too small for comfort or too weak to safely support the user during the climbing or descending tasks. An apparatus that is still lighter in weight is needed to provide improved portability without sacrificing safety and structural stability.  
           [0008]    Another need in climbing stands is a means for gripping the surface of the tree or pole that is sufficiently firm yet releasable to allow the repeated engaging and disengaging during the climbing and descending tasks. Gripping surfaces range from the bare edges of plain tubular or rectangular steel frame members described in the Manes patent, to the serrated edges described in Amaker and the spikes described in Gibson, et al. The gripping surfaces in the prior art that increase the friction between the device and the tree may be too sharp for an easy release while climbing or descending. Moreover, the addition of specialized gripping structures often adds weight to an already cumbersome device and/or expense to a price-sensitive manufacturing process.  
           [0009]    A number of tree climbing devices include elements that can be adjusted and locked in the field using cotter pins, nuts and bolts, straps, turnbuckles, or the spring-biased pins, for example, as described in the Manes patent. These mechanisms, however, create too much noise when adjusted in the field or when a hunter shifts his body position in the stand, especially in a hunting environment where silence and stealth is paramount. The noise of a rattling steel frame being extended or adjusted can destroy the entire advantage gained by climbing high enough to hide your presence.  
           [0010]    Thus, there remains a need for a tree climbing device that is lightweight yet strong, equipped with effective yet temporary gripping surfaces, and adjustable yet quiet to prevent interference with the hunting task.  
         SUMMARY OF THE INVENTION  
         [0011]    The above and other needs are met by the present invention which, in one embodiment, provides an improved portable tree climbing device and platform for hunters. Generally described, the present invention comprises an apparatus for climbing a columnar structure such as a tree or pole, and for supporting a person at a height above the ground. The apparatus includes a first frame section that can be opened to surround the pole. The first frame section includes a pair of side rails rigidly connected by a lower cross brace and a removable upper cross brace. The upper cross brace has a series of gripping ridges along it, placed where they will frictionally engage the pole whenever the apparatus is subjected to a downward force that is eccentric relative to the central axis of the pole. The apparatus also includes a second frame section with a second pair of side rails that are telescopically mounted into the side rails of the first frame section. The second pair of side rails are also connected by a cross member. A flexible seat for the user is suspended between the first frame section and the cross member of the second frame section. In another aspect, the gripping ridges are configured to release the pole whenever the apparatus is subjected to an upward force that is eccentric relative to the central axis of the pole.  
           [0012]    In another embodiment, the lower cross brace of the first frame section has two parts: a lower rail connecting the first pair of side rails, and a pair of diagonal cleats extending from the lower rail to the side rails. Each of the diagonal cleats has a series of gripping ridges along it, placed where they will frictionally engage the pole whenever the apparatus is subjected to a downward force that is eccentric relative to the central axis of the pole. In another aspect, the gripping ridges are configured to release the pole whenever the apparatus is subjected to an upward force that is eccentric relative to the central axis of the pole.  
           [0013]    In another aspect of the invention, the upper cross brace has a hollow I-shaped core with a flat base and an arched top. The side walls and the arched stop are about thirty percent thicker than the flat base. The shape of the arched top accounts for about one third of the brace&#39;s total height.  
           [0014]    In another aspect, the diagonal cleats have an L-shaped cleat body with a straight leg and a hooked leg. The hooked leg is about one-and-a-half times thicker than the straight leg. The hooked leg has a linear section and a curved section. In one embodiment, the straight leg has a thickened section on its free that is about two times thicker than the rest of the straight leg.  
           [0015]    In another aspect, the side rails, cross braces, and other cross members each have a hollow D-shaped core with a flat wall, a top wall, a bottom wall, and a curved wall to complete the D shape. The top and bottom walls are about twice as thick as the flat wall, while the curved wall is only about 75% as thick as the flat wall. In another embodiment, the top and bottom walls are about one-and-a-half times thicker than the flat wall, and the curved wall is only about 50% as thick as the flat wall. In yet another embodiment, the top and bottom walls are about 20% thinner than the flat wall, and the curved wall is only about 50% as thick as the flat wall. In a final embodiment of the cross brace, the top and bottom walls are about equal in thickness to the flat wall, and the curved wall is about one-third thicker than the flat wall.  
           [0016]    In a second embodiment, the apparatus includes a first frame section that can be opened to surround the pole. The first frame section includes a pair of side rails rigidly connected by a lower cross brace, a removable upper cross brace, and a pair of diagonal cleats. Each of the diagonal cleats has a series of gripping ridges along it, placed where they will frictionally engage the pole whenever the apparatus is subjected to a downward force that is eccentric relative to the central axis of the pole.  
           [0017]    The apparatus also includes a second frame section with a second pair of side rails that are telescopically mounted into the side rails of the first frame section. The second pair of side rails are also connected by a cross member. A flexible seat for the user is suspended between the first frame section and the cross member of the second frame section. In another aspect, the gripping ridges are configured to release the pole whenever the apparatus is subjected to an upward force that is eccentric relative to the central axis of the pole.  
           [0018]    In one embodiment, the removable upper cross brace also includes gripping ridges that are likewise configured to engage and then release the pole.  
           [0019]    In another aspect of the invention, the upper cross brace, diagonal cleats, side rails, cross braces, and other cross members are formed as described above.  
           [0020]    In another aspect of the invention, the apparatus includes a first frame section that can be opened to surround the pole, and a second section. The first frame section has a pair of first side rails connected by a lower cross brace, and a removable upper cross brace. Each of the first side rails includes a first button stop. The second frame section is telescopically mounted to the first frame section by a pair of second side rails. Each of the second side rails includes a second button stop that rests against the first button stop when the second section is extended. A flexible seat for the user is suspended between the first frame section and the cross member of the second frame section.  
           [0021]    In one embodiment, the first side rails include locking screw that is positioned to frictionally engage the second side rails when tightened.  
           [0022]    In another embodiment, the apparatus also includes a third section. In this embodiment, the second side rails each include a third button stop and the third side rails includes a fourth button stop that rests against the third button stop when the third section is extended. In another aspect of this embodiment, the second side rails include locking screw that is positioned to frictionally engage the third side rails when tightened.  
           [0023]    In another aspect of the invention, an apparatus is provided for climbing a columnar structure having a central axis such as a pole. The apparatus includes a pair of climbing frames; namely an upper climbing frame and a lower climbing frame. Each climbing frame includes a pair of seat rails, an intermediate cross brace, and a removable upper cross brace attached to the seat rails. At least part of one side of each cross brace faces the pole. At least one of the cross braces includes a series of gripping ridges lengthwise along the side facing the pole. The gripping ridges are placed where they will frictionally engage the pole whenever the apparatus is subjected to a downward force that is eccentric relative to the central axis of the pole. In another aspect, the gripping ridges are configured to release the pole whenever the apparatus is subjected to an upward force that is eccentric relative to the central axis of the pole. In one embodiment, the lower climbing frame also includes another cross member between the seat rails.  
           [0024]    In another aspect of the invention, the apparatus includes a pair of climbing frames. Each climbing frame includes a pair of side rail components, at least one intermediate cross brace component connecting the side rails, and a removable upper cross brace component. Each of these components is constructed of a metal alloy material. The pair of climbing frames is configured structurally to support a person weighing up to 300 pounds. The pair of climbing frames together weigh less than 20 pounds.  
           [0025]    In one embodiment of the climbing frames, the cross-sectional area of the metal alloy material for each of the components measures less than 0.70 square inches. In another aspect of this embodiment, the climbing frames include the upper cross braces, diagonal cleats, side rails, cross braces, and other cross members as described above.  
           [0026]    In another aspect, the present invention provides an elongate upper brace for a climbing apparatus. The upper cross brace has a hollow I-shaped core with a flat base and an arched top. The side walls and the arched stop are about thirty percent thicker than the flat base. The shape of the arched top accounts for about one third of the brace&#39;s total height.  
           [0027]    In another aspect, the present invention provides an elongate cleat for a climbing apparatus. The cleats have an L-shaped cleat body with a straight leg and a hooked leg. The hooked leg is about one-and-a-half times thicker than the straight leg. The hooked leg has a linear section and a curved section. In one embodiment, the straight leg has a thickened section on its free that is about two times thicker than the rest of the straight leg.  
           [0028]    Thus, it is an object of the present invention to provide an improved tree climbing and sitting apparatus for engaging the trunk of a tree or pole and supporting a person such as a hunter above the ground.  
           [0029]    It is a further object of the present invention to provide improved, lightweight frame members having ridges at key locations for increased strength and durability.  
           [0030]    It is another object of the present invention to provide an apparatus with improved gripping ability by including substantially parallel ridges at critical locations on the surfaces where the apparatus engages the tree or pole during climbing and descending.  
           [0031]    It is a further object of the present invention to quiet the moving parts of the climbing apparatus with softer stops and tighter locking mechanisms.  
           [0032]    Other features, objects and advantages of the present invention will become apparent upon reading the following specification when taken in conjunction with the drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0033]    [0033]FIG. 1 is a pictorial view of a climbing assembly according to the present invention, including a seat assembly and a foot climber connected by straps, shown mounted on a tree and supporting a hunter.  
         [0034]    [0034]FIG. 2 is a plan view of a seat assembly according to the present invention.  
         [0035]    [0035]FIG. 3 is a cross-sectional view of a first side rail of the seat assembly, according to the present invention, taken along line  3 - 3  of FIG. 2.  
         [0036]    [0036]FIG. 4 is a cross sectional view of a second side rail of the seat assembly, according to the present invention, taken along line  44  of FIG. 2.  
         [0037]    [0037]FIG. 5 is a cross sectional view of a third side rail of the seat assembly, according to the present invention, taken along line  5 - 5  of FIG. 2.  
         [0038]    [0038]FIG. 6 is a schematic plan view of a seat assembly according to the present invention.  
         [0039]    [0039]FIG. 7 is a cross sectional view of an upper tree-engaging brace, according to the present invention, taken along line  7 - 7  of FIG. 6.  
         [0040]    [0040]FIG. 8 is a cross sectional view of a first cross member of the seat assembly, according to the present invention, taken along line  8 - 8  of FIG. 6.  
         [0041]    [0041]FIG. 9 is a cross sectional view of a second cross member of the seat assembly, according to the present invention, taken along line  9 - 9  of FIG. 6.  
         [0042]    [0042]FIG. 10 is a cross sectional view of a third cross member of the seat assembly, according to the present invention, taken along line  10 - 10  of FIG. 6.  
         [0043]    [0043]FIG. 11A is a cross sectional view of a first cross member, a diagonal cleat, and an upper tree-engaging brace of the seat assembly, according to the present invention, taken along line  11 A- 11 A of FIG. 6.  
         [0044]    [0044]FIG. 11B is a schematic view of a series of button stops and a locking screw mounted to the side rails of the seat assembly, according to the present invention.  
         [0045]    [0045]FIG. 12A is a cross sectional view of a diagonal cleat according to the present invention, taken along line  12 A- 12 A of FIG. 6.  
         [0046]    [0046]FIGS. 12B and 12C are orthographic views of a diagonal cleat according to the present invention.  
         [0047]    [0047]FIG. 13 is a plan view of a foot climber, according to the present invention.  
         [0048]    [0048]FIG. 14 is a cross-sectional view of a side rail of the foot climber, according to the present invention, taken along line  14 - 14  of FIG. 13.  
         [0049]    [0049]FIG. 15 is a cross sectional view of a lower tree-engaging brace, according to the present invention, taken along line  15 - 15  of FIG. 13.  
         [0050]    [0050]FIG. 16 is a cross sectional view of a cross member of the foot climber, according to the present invention, taken along line  16 - 16  of FIG. 13.  
         [0051]    [0051]FIG. 17 is a cross sectional view of a toe tube of the foot climber, according to the present invention, taken along line  17 - 17  of FIG. 13.  
         [0052]    [0052]FIG. 18 is a cross sectional view of a heel bar of the foot climber, according to the present invention, taken along line  18 - 18  of FIG. 13.  
         [0053]    [0053]FIG. 19 is a pictorial view of the seat assembly, according to the present invention, shown in its collapsed position for transport.  
         [0054]    [0054]FIG. 20 is an orthographic drawing of a first side rail of the seat assembly, according to the present invention.  
         [0055]    [0055]FIG. 21 is an orthographic drawing of a second side rail of the seat assembly, according to the present invention.  
         [0056]    [0056]FIG. 22 is an orthographic drawing of a third side rail of the seat assembly, according to the present invention.  
         [0057]    [0057]FIG. 23 is an orthographic drawing and a perspective view of a button stop, according to the present invention.  
         [0058]    [0058]FIG. 24 is a pictorial view of a foot climber, according to the present invention, shown mounted on a tree.  
         [0059]    [0059]FIG. 25 is an orthographic drawing of a foot climber according to the present invention.  
         [0060]    [0060]FIG. 26 is an orthographic drawing of a foot climber diagonal cleat of the foot climber, according to the present invention.  
         [0061]    [0061]FIG. 27 is an orthographic drawing of an upper tree-engaging foot climber brace of the foot climber, according to the present invention.  
         [0062]    [0062]FIG. 28 is an orthographic drawing of a cross member of the foot climber, according to the present invention.  
         [0063]    [0063]FIG. 29 is an orthographic drawing of a toe tube of the foot climber, according to the present invention.  
         [0064]    [0064]FIG. 30 is an orthographic drawing of a heel bar of the foot climber, according to the present invention.  
         [0065]    [0065]FIG. 31 is an orthographic drawing of a side rail of the foot climber, according to the present invention.  
         [0066]    [0066]FIG. 32 is a pictorial view of an upper tree-engaging brace and side rails of the seat assembly, according to the present invention, shown mounted on a tree.  
         [0067]    [0067]FIG. 33 is a pictorial view of a seat assembly according to the present invention, shown mounted on a tree. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0068]    Referring now in more detail to the drawings, in which like numerals represent like parts throughout the several views, FIG. 1 shows a climbing assembly  10 , which includes a seat assembly  110  and a foot climber  210  in one embodiment. Straps  41 L,  41 R tether the seat assembly  110  to the foot climber  210  and, in one embodiment, also act as carrying straps for the assembly  10 . The climbing assembly  10  in FIG. 1 is shown supporting a seated hunter  43  in a tree  11 .  
         [0069]    The climbing assembly  10  can be used by a person to climb a generally vertical and columnar structure such as, without limitation, a tree trunk, a mast, a column or pillar, a utility pole, or any other type of pole. It should be understood that the climbing assembly  10  is suited for use at any height, and on structures of any shape. Although reference is made throughout to its use with a tree, the climbing assembly  10  is not limited to trees or even to structures that are cylindrical. The climbing assembly  10  can be fastened to any structure that fits between the space generally bounded by the side rails, the diagonal cleats, and the upper braces. In one embodiment, as shown in FIG. 1, both the seat assembly  110  and the foot climber  210  are sized to permit assembly around a columnar structure having an effective diameter of between eight inches and eighteen inches. The climbing assembly  10  is approximately 20.5 inches wide in the embodiment shown in the drawings, although it can be sized to accommodate structures of other shapes and sizes.  
       Seat Assembly  
       [0070]    [0070]FIG. 2 is a plan view of the seat assembly  110  positioned around a tree  11  and illustrating the flexible seat  38 . A flexible seat  38  extends between the first cross member  115  and the second cross member  126 , to support the user or hunter  43  (depicted in FIG. 1). The material for the flexible seat  38  preferably comprises a woven material of sufficient strength to support a person&#39;s weight; however, it will be understood that any suitable flexible material of sufficient strength can be utilized. The flexible seat  38  is connected to the first and second cross members  115 ,  126 , in one embodiment, by rivets  39  or the like. Other means of sufficiently durable and safe attachment can be used.  
         [0071]    As shown in both FIG. 2 and FIG. 6, the seat assembly  110  includes a first frame section  12 , a second frame section  23 , and a third frame section  32 .  
         [0072]    The first frame section  12  includes a pair of first side rails  113 L,  113 R rigidly connected in spaced-apart parallel relation by a first cross member  115  having a length sufficient to permit columnar structures having a moderately large effective diameter to fit between the first side rails  113 L,  113 R. The letter designations, L and R, are used throughout to signify components which are located, generally, toward the Left side or Right side, respectively, of the tree  11  or other columnar structure, from the perspective of a user facing the seat portion of the installed assembly  10 .  
         [0073]    A pair of tree-engaging diagonal cleats  116 L,  116 R are mounted to and extend diagonally from the cross member  115  to opposing points along the first side rails  113 L,  113 R. The diagonal cleats  116 L,  116 R serve as tree-engaging members and also brace the connection between the cross member  115  and the first side rails  113 L,  113 R. Moreover, the diagonal cleats  116 L,  116 R provide engagement between the seat assembly  110  and any columnar structures having a variety of shapes, sizes, and diameters. In one embodiment, the diagonal cleats  116 L,  116 R are mounted at a forty-five degree angle relative to the cross member  115 , but other angles and configurations are contemplated by this invention.  
         [0074]    The second frame section  23  includes a pair of second side rails  124 L,  124 R rigidly connected in spaced-apart parallel relation by an second cross member  126 . The second side rails  124 L,  124 R, in one embodiment, are sized and shaped to fit within the hollow centers of the first side rails  113 L,  113 R.  
         [0075]    The third frame section  32  includes a pair of third side rails  133 L,  133 R rigidly connected in spaced-apart parallel relation by an third cross member  135 , which may also serve as a foot rest (as shown in FIG. 1) for a seated user. The third side rails  133 L,  133 R, in one embodiment, are sized and shaped to fit within the hollow centers of the second side rails  124 L,  124 R.  
         [0076]    In one embodiment, the seat assembly  110  is collapsible, as shown in FIG. 19. The foot climber  210  may be strapped to the seat assembly  110  such that the entire assembly  10  may be carried using straps  41 L,  41 R.  
         [0077]    Portability is an important advantage of the design of the climbing assembly  10  because it allows hunters  43  and other types of users to transport the assembly  10  easily to another location where climbing is desired. The climbing assembly  10  of the present invention weighs about 25% less than other tree stands that are constructed of standard rectangular steel tubing, which can weigh up to twenty-five (25) pounds.  
         [0078]    For hunters in particular, the portability of the climbing assembly of the present invention offers several advantages. The chance of seeing the game being hunted is greatly increased if the hunter is able to rotate hunting sites rather than hunt the same area every day. Hunters may also find tracks or other signs left by game, making it desirable to relocate to the new, more active location. Also, other hunters may over-hunt or crowd a particular area, making it desirable for a hunter to change locations.  
         [0079]    In a preferred embodiment, the seat assembly  110  is collapsible through the use of telescoping side rails. The side rails are sized and shaped to fit within one another, as shown in FIGS. 3, 4, and  5 , with the first side rails  113 L,  113 R being the largest, the second side rails  124 L,  124 R being smaller, and the third side rails  133 L,  133 R being still smaller. In the preferred telescoping configuration, the first side rails  113 L,  113 R are located closest to the tree-gripping components in the first frame section  12 , where strength is most needed. Although the preferred embodiment of the invention includes telescoping tubular arms that slide into one another as shown in the drawing, it should be understood that other means of collapsibly attaching the second and third frame sections to the first frame section could be utilized in order to unfold and support the flexible seat  38  within the scope of the invention.  
         [0080]    The right side rails  113 R,  124 R,  133 R of all three frame sections  12 ,  23 ,  32  of the seat assembly  110  are shown in cross section in FIGS. 3, 4, and  5 , respectively. The first side rail  113 R shown in FIG. 3 is generally D-shaped and hollow in cross section, with its flat wall  513  being generally vertical and facing inwardly. Similarly, the second side rail  124 R shown in FIG. 4 is generally D-shaped and hollow in cross section, with its flat wall  524  being generally vertical and facing inwardly. The second side rail  124 R includes a plurality of second rail ridges  324  disposed along the entire length of its outer surface. Like the second side rail  124 R, the third side rail  133 R shown in FIG. 5 also includes a plurality of third rail ridges  333  disposed along the entire length of its outer surface. The third side rail  133 R shown in FIG. 5 is also generally D-shaped and hollow in cross section, with its flat wall  533  being generally vertical and facing inwardly.  
         [0081]    The side rails  113 L,  113 R,  124 L,  124 R,  133 L,  133 R are generally D-shaped and hollow in cross section to improve strength and durability compared to simple rectangular tubing. The side rails include rounded corners, rail ridges at select locations, and side walls of varying thickness for reduced weight and optimal strength. The rounded shapes also make gripping the various components easier and more comfortable.  
         [0082]    More specifically, the right first side rail  113 R, as shown in FIG. 3 and FIG. 20, has a flat wall  513 , a top wall  613 T, a bottom wall  613 B, and a curved wall  713 . When assembled as part of the seat assembly  110 , the flat wall  513  of the right first side rail  113 R is oriented in a generally vertical and inward-facing direction. In one embodiment, the height of the flat wall  513  may be between 1.98 and 2.02 inches (with a preferred height of 2 inches) and the full width of the side rail  113 R may be between 1.24 and 1.28 inches (with a preferred width of 1.26 inches). In this aspect, the height-to-width ratio for the side rail  113 R in this embodiment ranges from about 1.5-to-1 to about 1.6-to-1 (with a preferred ratio of about 1.6-to-1, or about one-and-a-half to 1). The corners between the flat wall  513  and the top and bottom walls  613 T,  613 B are formed with a radius for a smooth transition.  
         [0083]    The wall thickness of the right first side rail  113 R varies, in one embodiment, from between 0.09 and 0.11 inches (0.1 inches preferably) along the flat wall  513 , to between 0.13 and 0.16 inches (0.14 inches preferably) across the top and bottom walls  613 T,  613 B, and gradually thins to between 0.05 and 0.07 inches (0.06 inches preferably) along the curved wall  713 . In this aspect, the top and bottom walls  613 T,  613 B are between 1.2 and 1.8 times thicker (about one-and-a-half times or 1.4 times thicker, preferably) than the flat wall  513 . The curved wall  713  becomes gradually thinner toward its apex or narrowest point, where the thickness is between 45% and 78% (60% preferably) of the thickness of the flat wall  513 .  
         [0084]    The walls of the first side rails  113 R,  113 L do not include ridges in the embodiment shown in FIG. 3, but the addition of ridges for improved strength and other characteristics is contemplated.  
         [0085]    The overall cross-sectional area of each of the first side rails  113 L,  113 R is approximately 0.58 square inches in one embodiment, although more or less area may be required to accommodate a particular intended use. All corners are formed with a radius. The left first side rail  113 L has the same range of dimensions and ratios and, in a preferred embodiment, is a mirror image of the right first side rail  113 R. When assembled as part of the seat assembly  110 , the flat wall of the left first side rail  113 L is oriented in a generally vertical and inward-facing direction.  
         [0086]    The right second side rail  124 R, as shown in FIG. 4 and FIG. 21, has a flat wall  524 , a top wall  624 T, a bottom wall  624 B, and a curved wall  724 . A series of second rail ridges  324  are formed along the top and bottom walls  624 T,  624 B. When assembled as part of the seat assembly  110 , the flat wall  524  of the right second side rail  124 R is oriented in a generally vertical and inward-facing direction. In one embodiment, the height of the flat wall  524  may be between 1.62 and 1.67 inches (with a preferred height of 1.64 inches) and the full width of the side rail  124 R may be between 0.98 and 1.02 inches (with a preferred width of 1 inch). In this aspect, the height-to-width ratio for the side rail  124 R in this embodiment ranges from about 1.6-to-1 to about 1.7-to-1 (with a preferred ratio of 1.6-to-1, or about one-and-a-half to 1). The corners between the flat wall  524  and the top and bottom walls  624 T,  624 B are formed with a radius for a smooth transition.  
         [0087]    The wall thickness of the right second side rail  124 R varies, in one embodiment, from between 0.075 and 0.095 inches (0.085 inches preferably) along the flat wall  524 , to between 0.17 and 0.21 inches (0.19 inches preferably) across the top and bottom walls  624 T,  624 B, and gradually thins to between 0.05 and 0.07 inches (0.06 inches preferably) along the curved wall  724 . In this aspect, the top and bottom walls  624 T,  624 B are between 1.8 and 2.8 times (preferably, about two times or 2.3 times) thicker than the flat wall  524 . The curved wall  724  becomes gradually thinner toward its apex or narrowest point, where the thickness is between 53% and 93% (preferably, 71%) of the thickness of the flat wall  524 .  
         [0088]    The second side rails  124 R,  124 L include a series of second rail ridges  324  in the embodiment shown in FIG. 3, located generally along the top and bottom walls  624 T,  624 B. In one embodiment, three (3) second rail ridges  324  are provided on each of the top and bottom walls  624 T,  624 B, respectively, although any number of ridges may be suitable for a particular use. The second rail ridges  324  may be randomly spaced or evenly spaced across the outer surface of the second side rails  124 R,  124 L. The second rail ridges  324  may have a nominal height in one embodiment of 0.031 inches and a nominal width of 0.063 inches. In this embodiment, the width-to-height ratio is about 2-to-1.  
         [0089]    In one embodiment, the second rail ridge  324  closest to the curved wall  724  is about 0.043 inches high on the side closest to the flat wall  524  side of the second side rail  124 R,  124 L and the nominal 0.031 inches high on the other side. In this aspect, the higher side of the second rail ridge  324  closest to the curved wall  724  is about one-and-a-half times, or 1.4 times, higher than the other side.  
         [0090]    The overall cross-sectional area of each of the second side rails  124 L,  124 R is approximately 0.47 square inches in one embodiment, although more or less area may be required to accommodate a particular intended use. All corners are formed with a radius. The left second side rail  124 L has the same range of dimensions and ratios and, in a preferred embodiment, is a mirror image of the right second side rail  124 R. When assembled as part of the seat assembly  110 , the flat wall of the left second side rail  124 L is oriented in a generally vertical and inward-facing direction.  
         [0091]    The right third side rail  133 R, as shown in FIG. 5 and FIG. 22, has a flat wall  533 , a top wall  633 T, a bottom wall  633 B, and a curved wall  733 . A series of third rail ridges  333  are formed along the top and bottom walls  633 T,  633 B. When assembled as part of the seat assembly  110 , the flat wall  533  of the right third side rail  133 R is oriented in a generally vertical and inward-facing direction. In one embodiment, the height of the flat wall  533  may be between 1.13 and 1.17 inches (with a preferred height of 1.15 inches) and the full width of the side rail  133 R may be between 0.57 and 0.62 inches (with a preferred width of 0.6 inches). In this aspect, the height-to-width ratio for the side rail  133 R in this embodiment ranges from about 1.8-to-1 to about 2.0-to-1 (with a preferred ratio of 1.9-to-1, or about two to one). The corners between the flat wall  533  and the top and bottom walls  633 T,  633 B are formed with a radius for a smooth transition.  
         [0092]    The wall thickness of the right third side rail  133 R varies, in one embodiment, from between 0.07 and 0.09 inches (0.08 inches, preferably) along the flat wall  533 , to between 0.14 and 0.17 inches (0.16 inches, preferably) across the top and bottom walls  633 T,  633 B, and gradually thins to between 0.05 and 0.07 inches (0.06 inches, preferably) along the curved wall  733 . In this aspect, the top and bottom walls  633 T,  633 B are between 1.6 and 2.4 times (preferably, 2 times) thicker than the flat wall  533 . The curved wall  733  becomes gradually thinner toward its apex or narrowest point, where the thickness is between 55% and 100% (preferably, 75%) of the thickness of the flat wall  533 .  
         [0093]    The third side rails  133 R,  133 L include a series of third rail ridges  333  in the embodiment shown in FIG. 3, located generally along the top and bottom walls  633 T,  633 B. In one embodiment, a total of four (4) third rail ridges  333  are provided: one (1) each on the top and bottom walls  633 T,  633 B, respectively; and two (2) on the curved wall  733 . Any other number of ridges may be suitable for a particular use. The third rail ridges  333  may be randomly spaced or evenly spaced across the outer surface of the third side rails  133 R,  133 L. In the embodiment shown in FIG. 5, each pair of third rail ridges  333  is spaced approximately thirty degrees apart, radially, from a center point near the center of the flat wall  533 . The third rail ridges  333  may have a nominal height in one embodiment of 0.031 inches and a nominal width of 0.063 inches. In this embodiment, the width-to-height ratio is about 2-to-1.  
         [0094]    The overall cross-sectional area of each of the third side rails  133 L,  133 R is approximately 0.24 square inches in one embodiment, although more or less area may be required to accommodate a particular intended use. All corners are formed with a radius. The left third side rail  133 L has the same range of dimensions and ratios and, in a preferred embodiment, is a mirror image of the right third side rail  133 R. When assembled as part of the seat assembly  110 , the flat wall of the left third side rail  133 L is oriented in a generally vertical and inward-facing direction.  
         [0095]    In a preferred embodiment, the structural components of the assembly  10  are made of extruded aluminum; preferably, 6005-T6 Aluminum alloy. Aluminum is an abundant mineral and its alloys produce components that have excellent strength, durability, corrosion resistance, and a lighter weight than steel. The aluminum extrusion process is capable of producing lengths of aluminum bar, channels, and angles, as well as customized shapes with solid, semi-hollow, or hollow profiles.  
         [0096]    In one aspect of the present invention, the size and shape of the structural components for the assembly  10  are optimized to provide improved strength where support is needed, while reducing the thickness and weight of the rail where less support is needed. The D-shaped, hollow components provide improved stiffness, strength, and durability compared to standard rectangular tubing.  
         [0097]    In a preferred embodiment, the climbing assembly  10  weighs approximately nineteen (19) pounds and is configured to support a load of up to three hundred (300) pounds. In this aspect, the strength-to-weight ratio for the climbing assembly  10  is more than 15-to-1.  
         [0098]    Referring again to FIG. 6, an upper tree-engaging brace  120  is provided for attachment to the first side rails  113 L,  113 R after the seat assembly  110  is placed around the tree or other columnar structure. The upper tree-engaging brace  120  is shown in its fastened position in FIGS. 6, 11A,  32 , and  33 . The upper tree-engaging brace  120  is fastened to the first side rails  113 L,  113 R by means of locking bolts  121 L,  121 R, respectively. The locking bolts  121 L,  121 R (shown in FIG. 32) may be placed through aligned openings in the brace  120  and through one of the holes  19 L,  19 R in the first side rails  113 L,  113 R.  
         [0099]    As illustrated in FIG. 7, the upper tree-engaging brace  120  is generally I-shaped and hollow in cross section, in one embodiment, and includes a plurality of upper brace ridges  320 . The upper brace ridges  320  are positioned on the thickened and rounded outer corners of the top wall  720 , in precisely the area where the brace  120  is configured to engage the surface of the tree  11  or pole during climbing or descending. The base wall  520  of the brace  120  rests upon the first side rails  113 L,  113 R when installed, as shown in FIG. 11A.  
         [0100]    The upper brace  120  functions as an adjustable tree-engaging member, which can be adjusted closer to or farther away from the diagonal cleats  116 L,  116 R by means of the holes  19 L,  19 R. A number of holes  19 L,  19 R, such as seven (7) holes for some applications, may be provided in the first side rails  113 L,  113 R, and they may be randomly spaced or evenly spaced, depending on the expected conditions. In one embodiment, as illustrated in FIG. 20, the holes  19 L,  19 R are spaced two inches apart. A plurality of holes  19 L,  19 R are provided in order to accommodate a variety of columnar structures or trees  11  having different diameters.  
         [0101]    As shown in FIG. 11A, the side wall  620 L is the lowermost side wall when the assembly  10  is in its cantilevered position, whereas the side wall  620 U is the uppermost side wall. Unlike a rectilinear tube, the I-shaped upper brace  120  includes thickened and rounded corners and side walls  620 L,  620 U that are somewhat thinner in certain areas than the nominal wall thickness.  
         [0102]    More specifically, the upper tree-engaging brace  120 , as shown in FIG. 7, has a base wall  520 , a lower side wall  620 L, an upper side wall  620 U, and a top wall  720 . In one embodiment, the width of the base wall  520  may be between 1.97 and 2.03 inches (2 inches, preferably) and the total height of the upper brace  120  may be between 1.48 and 1.52 inches (1.5 inches preferably). In this aspect, the width-to-height ratio for the upper brace  120  in this embodiment ranges from about 1.3-to-1 to about 1.4-to-1 (preferably, 1.33-to-1). The opposing ends of the base wall  520  extend about one quarter of an inch beyond the side walls  620 L,  620 U on both sides. Likewise, the opposing ends of the top wall  720  extend about one quarter of an inch beyond the side walls  620 L,  620 U on both sides.  
         [0103]    The top wall  720  of the upper brace  120  is somewhat arch-shaped in cross section, having a top surface that is generally flat across about one-third of its total width, and gently rounded ends where the upper brace ridges  320  are located and where the top wall  720  meets the side walls  620 L,  620 U. In one embodiment, the side walls  620 L,  620 U are approximately 1 inch high. In this aspect, the side walls  620 L,  620 U occupy between 67% and 69% of the total height of the upper brace  120 , whereas the arch-shaped top wall  720  occupies the remaining 31% to 33% of the total height. In other words, the side walls  620 L,  620 U extend to roughly two thirds of the total height of the upper brace  120 , with the arch-shaped top wall  720  occupying the remaining third.  
         [0104]    The wall thickness of the upper brace  120  varies at different locations. In one embodiment, the thickness of the base wall  520  is between 0.05 and 0.07 inches (0.06 inches, preferably). The thickness of the lower and upper side walls  620 L,  620 U are between 0.07 and 0.09 inches (0.08 inches, preferably). In this aspect, the lower and upper side walls  620 L,  620 U are between 1 and 1.7 times (preferably, about one-and-a-half times, or 1.3 times) thicker than the base wall  520 . Similarly, the thickness of the top wall  720  is between 0.07 and 0.09 inches (0.08 inches, preferably). In this aspect, the top wall  720  is between 1 and 1.7 times (preferably, about one-and-a-half times, or 1.3 times) thicker than the base wall  520 .  
         [0105]    The opposing ends of the base wall  520  are formed with a thickness of between 0.18 and 0.2 inches (0.19 inches, preferably). In this embodiment, the thicker ends of the base wall  520  are between 2.4 and 3.6 times (preferably, 2.9 times or about three times) thicker than the central portion of the base wall  520 . Compared to the thickness of the lower and upper side walls  620 L,  620 U, the opposing ends of the base wall  520  are 0.25 inches wider in that direction. The total width, therefore, of the opposing ends of the base wall  520  is between 0.32 and 0.34 inches (0.33 inches, preferably). In this embodiment, then, the opposing ends of the base wall  520  are between 3.4 and 4.6 times (preferably, 3.9 times or about four times) thicker than the lower and upper side walls  620 L,  620 U.  
         [0106]    Like the base wall  520 , the top wall  720  has opposing ends that are thicker than the central section of the top wall  720  and wider than the thickness of the lower and upper side walls  620 L,  620 U. In one embodiment, the opposing ends of the top wall  720  are thicker and wider in the same proportions as the opposing ends of the base wall  520 . In other words, the opposing ends of the top wall  720  are between 2.4 and 3.6 times (preferably, 2.9 times or about three times) thicker than the central portion of the base wall  520 . Also, the opposing ends of the top wall  720  are between 3.4 and 4.6 times (preferably, 3.9 times or about four times) thicker than the lower and upper side walls  620 L,  620 U.  
         [0107]    The upper brace  120  includes a series of upper brace ridges  320 , in the embodiment shown in FIG. 7, located generally along the outer surface of the opposing ends of the top wall  720 . In one embodiment, three (3) distinct upper brace ridges  320  are defined by a series of grooves formed in the top wall  720  next to each ridge  320 . It should be noted that the provision of ridges on the surfaces disclosed and described herein may be formed by adding material that extends above the nominal surface of the component, or by subtracting material to create grooves that extend below the nominal surface of the component, or by a combination of these or other fabrication methods.  
         [0108]    In the preferred embodiment of the present invention, the ridges and other features are formed during a metal alloy extrusion process. A die is cut which includes the ridged shape in the desired locations. When the aluminum alloy billet is forced through the die plate and/or the mandrel and cap sections, the result is a length of aluminum alloy with ridges matching the shape of the die. Aluminum extrusions are formed to a specified tolerance, which means that certain dimensions disclosed herein are expressed using a range. For example, a distance of 1.10 inches, plus or minus a tolerance of 0.10 inches, may be expressed as a distance of between 1.0 and 1.2 inches (preferably, 1.1 inches) in order to indicate the acceptable range of distances.  
         [0109]    Referring again to the embodiment shown in FIG. 7, three (3) distinct brace ridges  320  are provided on the curved outer ends of the top wall  720  of upper brace  120 . While three brace ridges  320  are provided in this embodiment, any number of ridges may be suitable for a particular use. The brace ridges  320  may be randomly spaced or evenly spaced. The brace ridges  320  may have a nominal height in one embodiment of 0.031 inches and a nominal width of 0.063 inches. In this embodiment, the width-to-height ratio is approximately 2-to-1.  
         [0110]    The overall cross-sectional area of each of the upper brace  120  is approximately 0.62 square inches in one embodiment, although more or less area may be required to accommodate a particular intended use. All corners are formed with a radius.  
         [0111]    The cross members  115 ,  126 ,  135  of all three frame sections  12 ,  23 ,  32  of the seat assembly  110 , respectively, are shown in cross section in FIGS. 8, 9, and  10 . The first cross member  115  shown in FIG. 8 is generally D-shaped and hollow in cross section, with its flat side facing toward the pole or tree  11 . The second cross member  126  shown in FIG. 9 is also generally D-shaped and hollow in cross section, but its flat side faces away from the pole. The second cross member  126  also includes a plurality of second cross member ridges  326  disposed along the entire length of its outer surface. Like the second cross member  126 , the third cross member  135  shown in FIG. 10 also includes a plurality of ridges (called third cross member ridges  335 ) disposed along the entire length of its outer surface and its flat side faces away from the pole.  
         [0112]    The first cross member  115 , as shown in FIG. 8, has a flat wall  515 , a top wall  615 T, a bottom wall  615 B, and a curved wall  715 . When assembled as part of the seat assembly  110 , the flat wall  515  of the first cross member  115  is oriented in a generally vertical direction facing the pole or tree  11 . In one embodiment, the height of the flat wall  515  may be between 1.98 and 2.02 inches (with a preferred height of 2 inches) and the full width of the first cross member  115  is preferably 1.4 inches. In this aspect, the height-to-width ratio for the first cross member  115  in this embodiment ranges from about 1.4-to-1 to about 1.45-to-1 (with a preferred ratio of about 1.4-to-1, or about one-and-a-half to one). The corners between the flat wall  515  and the top and bottom walls  615 T,  615 B are formed with a radius for a smooth transition.  
         [0113]    The wall thickness of the first cross member  115  varies, in one embodiment, from between 0.09 and 0.11 inches (0.1 inches preferably) along the flat wall  515 , to between 0.14 and 0.16 inches (0.15 inches preferably) across the top and bottom walls  615 T,  615 B, and gradually thins to between 0.05 and 0.07 inches (0.06 inches preferably) along the curved wall  715 . In this aspect, the top and bottom walls  615 T,  615 B are between 1.2 and 1.8 times thicker (1.4 times thicker, preferably, or about one-and-a-half times thicker) than the flat wall  515 . The curved wall  715  becomes gradually thinner toward its apex or narrowest point, where the thickness is between 45% and 78% (60% preferably) of the thickness of the flat wall  515 .  
         [0114]    The walls of the first cross member  115  do not include ridges in the embodiment shown in FIG. 8, but the addition of ridges for improved strength and other characteristics is contemplated.  
         [0115]    The overall cross-sectional area of the first cross member  115  is approximately 0.58 square inches in one embodiment, although more or less area may be required to accommodate a particular intended use. All corners are formed with a radius.  
         [0116]    The top wall  615 T of the first cross member  115  may include a series of pre-drilled holes to accommodate a series of fasteners  39  such as rivets or the like, for holding the fabric of the flexible seat  38  to the first cross member  115 . The flexible seat  38  is suspended between the first cross member  115  and the second cross member  126 .  
         [0117]    Likewise, the top wall  626 T of the second cross member  126  may include a series of pre-drilled holes to accommodate a series of fasteners  39  such as rivets or the like, for holding the fabric of the flexible seat  38  to the second cross member  126 .  
         [0118]    The second cross member  126 , as shown in FIG. 9, has a flat wall  526 , a top wall  626 T, a bottom wall  626 B, and a curved wall  726 . A series of second cross member ridges  326  are formed along the top and bottom walls  626 T,  626 B. When assembled as part of the seat assembly  110 , the flat wall  526  of the second cross member  126  is oriented in a generally vertical direction and faces away from the pole or tree  11 . In one embodiment, the height of the flat wall  526  may be between 1.62 and 1.67 inches (with a preferred height of 1.64 inches) and the second cross member  126  may be between 0.98 and 1.02 inches (with a preferred width of 1 inch). In this aspect, the height-to-width ratio for the second cross member  126  in this embodiment ranges from about 1.6-to-1 to about 1.7-to-1 (with a preferred ratio of 1.65-to-1, or about one-and-a-half to one). The corners between the flat wall  526  and the top and bottom walls  626 T,  626 B are formed with a radius for a smooth transition.  
         [0119]    The wall thickness of the second cross member  126  varies, in one embodiment, from between 0.07 and 0.09 inches (0.08 inches preferably) along the flat wall  526 , to between 0.17 and 0.21 inches (0.19 inches preferably) across the top and bottom walls  626 T,  626 B, and gradually thins to between 0.05 and 0.07 inches (0.06 inches preferably) along the curved wall  726 . In this aspect, the top and bottom walls  626 T,  626 B are between 1.8 and 2.8 times (preferably, 2.3 times or about two times) thicker than the flat wall  526 . The curved wall  726  becomes gradually thinner toward its apex or narrowest point, where the thickness is between 53% and 93% (preferably, 71%) of the thickness of the flat wall  526 .  
         [0120]    The second cross member  126  includes a series of second cross member ridges  326  in the embodiment shown in FIG. 9, located generally along the top and bottom walls  626 T,  626 B. In one embodiment, three (3) second cross member ridges  326  are provided on each of the top and bottom walls  626 T,  626 B, respectively, although any number of ridges may be suitable for a particular use. The second cross member ridges  326  may be randomly spaced or evenly spaced across the outer surface of the second cross member  126 . The second cross member ridges  326  may have a nominal height in one embodiment of 0.031 inches and a nominal width of 0.063 inches. In this embodiment, the width-to-height ratio is about 2-to-1.  
         [0121]    In one embodiment, the second cross member ridge  326  closest to the curved wall  726  is about 0.043 inches high on the side closest to the flat wall  526  side of the second cross member  126  and the nominal 0.031 inches high on the other side. In this aspect, the higher side of the second cross member ridge  326  closest to the curved wall  726  is 1.4 times higher or about one-and-a-half times higher than the other side.  
         [0122]    The overall cross-sectional area of the second cross member  126  is approximately 0.47 square inches in one embodiment, although more or less area may be required to accommodate a particular intended use. All corners are formed with a radius.  
         [0123]    The third cross member  135 , as shown in FIG. 10, has a flat wall  535 , a top wall  635 T, a bottom wall  635 B, and a curved wall  735 . A series of third cross member ridges  353  are formed along the top and bottom walls  635 T,  635 B. When assembled as part of the seat assembly  110 , the flat wall  535  of the third cross member  135  is oriented in a generally vertical direction facing away from the pole or tree  11 . In one embodiment, the height of the flat wall  535  may be between 1.13 and 1.17 inches (with a preferred height of 1.15 inches) and the full width of the third cross member  135  may be between 0.57 and 0.62 inches (with a preferred width of 0.6 inches). In this aspect, the height-to-width ratio for the third cross member  135  in this embodiment ranges from about 1.8-to-1 to about 2-to-1 (with a preferred ratio of 1.9-to-1, or about two to one). The corners between the flat wall  535  and the top and bottom walls  635 T,  635 B are formed with a radius for a smooth transition.  
         [0124]    The wall thickness of the third cross member  135  varies, in one embodiment, from between 0.07 and 0.09 inches (0.08 inches, preferably) along the flat wall  535 , to between 0.14 and 0.17 inches (0.16 inches, preferably) across the top and bottom walls  635 T,  635 B, and gradually thins to between 0.05 and 0.07 inches (0.06 inches, preferably) along the curved wall  735 . In this aspect, the top and bottom walls  635 T,  635 B are between 1.6 and 2.4 times (preferably, 2 times) thicker than the flat wall  535 . The curved wall  735  becomes gradually thinner toward its apex or narrowest point, where the thickness is between 55% and 100% (preferably, 75%) of the thickness of the flat wall  535 .  
         [0125]    The third cross member  135  includes a series of third cross member ridges  353  in the embodiment shown in FIG. 10, located generally along the top and bottom walls  635 T,  635 B. In one embodiment, four (4) third cross member ridges  353  are provided: one (1) each on the top and bottom walls  635 T,  635 B, respectively; and, two (2) on the curved wall  735 . Any other number of ridges may be suitable for a particular use. The third cross member ridges  353  may be randomly spaced or evenly spaced across the outer surface of the third cross member  135 . In the embodiment shown in FIG. 10, each pair of third cross member ridges  353  is spaced approximately thirty degrees apart, radially, from a center point near the center of the flat wall  535 . The third cross member ridges  353  may have a nominal height in one embodiment of 0.031 inches and a nominal width of 0.063 inches. In this embodiment, the width-to-height ratio is about 2-to-1.  
         [0126]    The overall cross-sectional area of each of the third cross member  135  is approximately 0.24 square inches in one embodiment, although more or less area may be required to accommodate a particular intended use. All corners are formed with a radius.  
         [0127]    Referring to FIG. 6, the first frame section  12  of the seat assembly  110  includes a pair of tree-engaging diagonal cleats  116 L,  116 R which, in one embodiment, are mounted to and extend diagonally from the flat wall  515  of the first cross member  115  to opposing points along the flat walls  513  of the first side rails  113 L,  113 R. The diagonal cleats  116 L,  116 R may be mounted to the first cross member  115  and to the first side rails  113 L,  113 R by welding or by any other suitably strong and durable means of attachment.  
         [0128]    [0128]FIG. 12A is a cross section of the right diagonal cleat  116 R. FIGS. 12B and 12C show other views of the diagonal cleats  116 L,  116 R. The diagonal cleats  116 L,  116 R, which are generally L-shaped in cross section, include rounded corners, rail ridges at select locations, and side walls of varying thickness for reduced weight and optimal strength.  
         [0129]    More specifically, the right diagonal cleat  116 R, as shown in FIG. 12A, has a flat wall  516  and a side wall  616 . A series of cleat ridges  316  are formed along the outer surface of the side wall  616 . When assembled as part of the seat assembly  110 , the flat wall  516  of the right diagonal cleat  116 R is oriented in a generally horizontal direction, facing upward. In one embodiment, the width of the flat wall  516  may be between 1.49 and 1.51 inches (with a preferred height of 1.5 inches) and the height of the side wall  616  may be between 1.51 and 1.56 inches (with a preferred width of 1.53 inches). In this aspect, the height-to-width ratio for the right diagonal cleat  116 R in this embodiment is about 1-to-1. The single corner between the flat wall  516  and the side walls  616  is formed with a radius for a smooth transition.  
         [0130]    The wall thickness of the right diagonal cleat  116 R varies, in one embodiment, from between 0.12 and 0.14 inches (0.13 inches, preferably) along the flat wall  516 , to between 0.18 and 0.2 inches (0.19 inches, preferably) along the side wall  616 . In this aspect, the side wall  616  is between 1.3 and 1.7 times (preferably, about one-and-a-half times) thicker than the flat wall  516 .  
         [0131]    The free end of the flat wall  516  is formed with additional thickness in both directions. In the vertical direction, the free end of the flat wall  516  has a thickness of between 0.24 and 0.26 inches (0.25 inches, preferably). Thus, in this embodiment, the free end of the flat wall  516  is twice as thick as the nominal thickness of the flat wall  516 . In the horizontal direction, the free end of the flat wall  516  has a thickness of between 0.3 and 0.32 inches (0.31 inches, preferably). The free end of the flat wall  516 , in this embodiment, is between 1.5 and 1.8 times (preferably, 1.6 times or about one-and-a-half times) thicker than the side wall  616 .  
         [0132]    The side wall  616  includes a straight section and a curved section. The cleat ridges  316  are located along the curved section in the embodiment shown in FIG. 12A. The nominal thickness of the side wall  616  is generally the same throughout the straight section and the curved section. In one embodiment, four (4) cleat ridges  316  are provided on the curved section of the side wall  616 , although any number of ridges may be suitable for a particular use. The cleat ridges  316  may be randomly spaced or evenly spaced. The cleat ridges  316  may have a nominal height in one embodiment of 0.031 inches and a nominal width of 0.063 inches. In this embodiment, the width-to-height ratio is about 2-to-1.  
         [0133]    The overall cross-sectional area of each of the right diagonal cleat  116 R is approximately 0.56 square inches in one embodiment, although more or less area may be required to accommodate a particular intended use. All corners are formed with a radius. The left diagonal cleat  116 L has the same range of dimensions and ratios and, in a preferred embodiment, is a mirror image of the right diagonal cleat  116 R. When assembled as part of the seat assembly  110 , the flat wall of the left diagonal cleat  116 L is oriented in a generally horizontal direction, facing upward.  
         [0134]    The cleat ridges  316  are positioned along the curved section of the side wall  616  where they will frictionally engage the surface of the tree  11  or pole during use. Different configurations, shapes, and sizes of the cleat ridges  316  may be suitable for a particular application. Use of the assembly  10  on a smooth utility pole, for example, may require more cleat ridges  316 , formed at a greater height, and/or with sharper edges than shown for an assembly  10  which is intended for use on a rougher tree trunk. The suggested dimensions given, for one embodiment, represent a preferred configuration for an assembly  10  that is particularly well-suited for engaging any of a variety of trees. Because other uses are contemplated, other dimensions and configurations may be appropriately developed that are within the scope of the invention disclosed.  
         [0135]    As depicted in FIG. 11A, the brace ridges  320  on the upper brace  120  and the cleat ridges  316  on the diagonal cleats  116 L,  116 R press into opposing sides of the pole or tree  11 . The wall thickness is increased at locations where the ridges  320 ,  316  are part of the upper brace  120  and the diagonal cleats  116 L,  116 R, respectively.  
         [0136]    It should be noted that the brace ridges  320 , the cleat ridges  316 , and any other ridges disclosed herein may be shaped in the form of raised ridges projecting above the nominal outer surface of a component or, alternatively, shaped in the form of depressed grooves below the nominal outer surface. It should be understood that any method of forming the ridges lies within the scope of the invention.  
         [0137]    The grip of the opposing ridges  320 ,  316 , in one aspect of the invention, allows the seat assembly  110  to frictionally engage the pole or tree  11 . The weight of a hunter  43  upon the climbing assembly  10 , for example, exerts an eccentric downward force with respect to the tree  11 . The assembly is generally cantilevered in its installed position. In use, the hunter&#39;s weight on the assembly  10  causes the brace ridges  320  on the upper brace  120  to press into the side of the pole or tree  11  and, simultaneously, the cleat ridges  316  on the diagonal cleats  116 L,  116 R press into the opposite side of the pole or tree  11 .  
         [0138]    In another aspect, the gripping ridges  320 ,  316  also provide a grip on the tree  11  that is more quickly and easily releasable when compared to other, more invasive gripping means such as serrated edges or spikes that pierce the tree or pole. Prompt release is an advantage because it reduces the work to be done by the user during the climbing process. The task of repeatedly engaging and releasing the assembly  10  from the tree  11  while climbing or descending requires constant attention by the user.  
         [0139]    [0139]FIG. 11B is a schematic view of a series of interior button stops  125 R,  114 R,  134 R,  127 R mounted to the right side rails  113 R,  124 R,  133 R of the seat assembly  10  in one embodiment of the present invention. Similar button stops are, likewise, mounted to the left side rails (not shown). The general size and shape of the button stop is shown in FIG. 23.  
         [0140]    As shown in FIG. 11B, the button stops  125 R,  114 R,  134 R,  127 R are sized and located to stop the relative motion of the adjacent right side rails  113 R,  124 R,  133 R. Button stop  114 R is fastened to the interior of the flat wall  513  of the first side rail  113 R with a rivet or other fastener near the end where the second side rail  124 R is nested within the first side rail  113 R.  
         [0141]    Button stop  125 R is fastened to the exterior of the flat wall  524  of the second side rail  124 R such that it rests against button stop  114 R when the second frame section  23  is fully extended. The second side rail  124 R also includes button stop  127 R, which is fastened to the interior of the flat wall  524  of the second side rail  124 R near the end where it nests with the third side rail  133 R. Finally, button stop  134 R is fastened to the exterior of the flat wall  533  of the third side rail  133 R such that it rests against button stop  127 R when the third frame section  32  is fully extended.  
         [0142]    [0142]FIGS. 20 through 22 show the general size and location of the button stops  125 L,  125 R,  114 L,  114 R,  134 L,  134 R,  127 L,  127 R relative to the frame sections  12 ,  23 ,  32 .  
         [0143]    [0143]FIG. 23 shows the shape of the button stops  125 L,  125 R,  114 L,  114 R,  134 L,  134 R,  127 L,  127 R in more detail. For some applications, all the button stops may be the same size and shape. Preferably, the stops are made of nylon or similar material. In one embodiment, the material used is Nylatron® GS, Molybdenum Disulfide-filled, Type 66 Nylon. The button stops may have a nominal thickness of two tenths of an inch and a nominal diameter of seven eighths of an inch for some applications. The embodiment shown in FIG. 23 includes a centrally disposed hole to accommodate a fastener such as a rivet, which may require a hole having a diameter of about 0.19 inches. The embodiment shown also includes a centrally located circular depression with a chamfered central rim, about 0.39 inches in diameter and extending to a depth of about one-half the nominal thickness. For some applications, as shown in FIG. 23, the button stop is thickest at its center, growing gradually thinner toward its outer rim at a rate of about three degrees.  
         [0144]    Different configurations, shapes, and sizes of the button stops  125 L,  125 R,  114 L,  114 R,  134 L,  134 R,  127 L,  127 R may be suitable for a particular application. The suggested dimensions given, for one embodiment, represent a preferred configuration for an assembly  10  that is particularly well-suited for supporting the sitting activity of a hunter in a tree when the frame sections are fully extended. Other activities may require button stops of different sizes and shapes, particularly when the size and shape of the frame rails may be modified to accommodate higher loads and stresses. Because other uses are contemplated, other dimensions and configurations may be appropriately developed that are within the scope of the invention disclosed.  
         [0145]    [0145]FIG. 11B also shows and a locking screw  240 R mounted to the right second side rail  124 R of the seat assembly  110 , in one embodiment. The locking screw  240 R is positioned to frictionally engage the top wall  633  of the right third side rail  133 R in order to prevent the rail  133 R from sliding. The locking screw  240 R acts as a control knob, preventing the rattling noise of relative movement between the frame sections  23 ,  32  and preventing any unintended extension of the third frame section  32  during use.  
       Foot Climber  
       [0146]    A foot climber  210  is provided, in one embodiment of the present invention, as shown in FIGS. 13, 24, and  25 . FIG. 13 is a plan view of the foot climber assembly  210  positioned around a tree  11 . FIG. 24 is a pictorial view and FIG. 25 is an engineering drawing including orthographic views of the side and top.  
         [0147]    In a preferred embodiment, the foot climber  210  includes a multi-piece structural frame, as shown in FIG. 13, to support a user. The frame comprises a pair of foot climber side rails  213 L,  213 R (shown in detail in FIG. 31), a foot climber cross member  215  (shown in detail in FIG. 28), a toe tube  226  (shown in detail in FIG. 29), and a heel bar  235  shaped to include heel bar ridges  435  (shown in detail in FIG. 30).  
         [0148]    The foot climber side rails  213 L,  213 R are rigidly connected in spaced-apart parallel relation by the foot climber cross member  215 , which has a length sufficient to permit columnar structures having a moderately large effective diameter to fit between the side rails  213 L,  213 R. A pair of tree-engaging foot climber diagonal cleats  216 L,  216 R are mounted to and extend diagonally from the cross member  215  to opposing points along the side rails  213 L,  213 R. The foot climber diagonal cleats  216 L,  216 R serve as tree-engaging members and also brace the connection between the cross member  215  and the side rails  213 L,  213 R. In one embodiment, the diagonal cleats  216 L,  216 R are mounted at a forty-five degree angle relative to the cross member  215 , but other angles and configurations are contemplated.  
         [0149]    The right foot climber side rail  213 R, as shown in cross section in FIG. 14, is generally D-shaped and hollow in cross section, with its flat side facing inwardly. Similarly, the opposing left side rail  213 L is similar in shape and its flat side facing inwardly. The side rails  213 L,  213 R are generally D-shaped in cross section to provide improved strength and durability compared to simple rectangular tubing. The side rails  213 L,  213 R include rounded corners, rail ridges, and side walls of varying thickness for reduced weight and optimal strength.  
         [0150]    More specifically, the right foot climber side rail  213 R, as shown in FIG. 14, has a flat wall  563 , a top wall  663 T, a bottom wall  663 B, and a curved wall  763 . When assembled as part of the seat assembly  110 , the flat wall  563  of the right foot climber side rail  213 R is oriented in a generally vertical and inward-facing direction. In one embodiment, the height of the flat wall  563  may be between 1.1 and 1.15 inches (with a preferred height of 1.13 inches) and the overall width of the right foot climber side rail  213 R may be between 1.1 and 1.15 inches (with a preferred height of 1.13 inches). In this aspect, the height-to-width ratio for the right foot climber side rail  213 R in this embodiment is 1-to-1. The corners between the flat wall  563  and the top and bottom walls  663 T,  663 B are formed with a radius for a smooth transition.  
         [0151]    The wall thickness of the right foot climber side rail  213 R vanes, in one embodiment, from between 0.09 and 0.11 inches (0.1 inches, preferably) along the flat wall  563 , thinning to between 0.08 and 0.09 inches (0.085 inches, preferably) across the top and bottom walls  663 T,  663 B, and further thinning, gradually, to between 0.05 and 0.07 inches (0.06 inches, preferably) along the curved wall  763 . In this aspect, the top and bottom walls  663 T,  663 B are up to 38% thinner (18% thinner, preferably, or about 20% thinner) than the flat wall  563 . The curved wall  763  becomes gradually thinner toward its apex or narrowest point, where the thickness is between 45% and 78% (60% preferably) of the thickness of the flat wall  563 .  
         [0152]    The walls of the right foot climber side rail  213 R do not include ridges in the embodiment shown in FIG. 14, but the addition of ridges for improved strength and other characteristics is contemplated.  
         [0153]    The overall cross-sectional area of the right foot climber side rail  213 R is approximately 0.31 square inches in one embodiment, although more or less area may be required to accommodate a particular intended use. All corners are formed with a radius. The left foot climber side rail  213 L has the same range of dimensions and ratios and, in a preferred embodiment, is a mirror image of the right foot climber side rail  213 R. When assembled as part of the seat assembly  110 , the flat wall of the left foot climber side rail  213 L is oriented in a generally vertical and inward-facing direction.  
         [0154]    A number of holes  219 L,  219 R, such as seven (7) holes for some applications, may be provided in the foot climber side rails  213 L,  213 R, and they may be randomly spaced or evenly spaced, depending on the expected conditions. In one embodiment, as illustrated in FIG. 25, the holes  219 L,  219 R are spaced two inches apart. The spacing and location of the foot climber holes  219 L,  219 R will, preferably, match the spacing and location of the holes  19 L,  19 R in the seat assembly  110 .  
         [0155]    Referring again to FIG. 13, an upper tree-engaging foot climber brace  220  is provided for attachment to the foot climber side rails  213 L,  213 R after the foot climber  210  is placed around the tree or other columnar structure. The upper brace  220  is shown in its fastened position in FIG. 24. The upper brace  220  is fastened to the foot climber side rails  213 L,  213 R by means of locking bolts  221 L,  221 R, respectively. The locking bolts  221 L,  221 R may be placed through aligned openings in the upper brace  220  and through one of the holes  219 L,  219 R in the foot climber side rails  213 L,  213 R.  
         [0156]    As illustrated in FIG. 15, the upper tree-engaging foot climber brace  220  is generally I-shaped and hollow in cross section, in one embodiment, and includes a plurality of upper brace ridges  420 . The upper brace ridges  420  are positioned on the thickened and rounded outer corners of the top wall  770 , in precisely the area where the brace  220  is configured to engage the surface of the tree  11  or pole during climbing or descending. The base wall  570  of the brace  220  rests upon the foot climber side rails  213 L,  213 R when installed, in a similar manner as the brace  120  shown in FIG. 11A.  
         [0157]    Referring to the brace  120  shown in FIG. 11A as a reference, the side wall  670 L of the brace  220 —like side wall  620 L—is the lowermost side wall when the assembly  10  is in its cantilevered position, whereas the side wall  670 U is the uppermost side wall. Unlike a rectilinear tube, the I-shaped upper brace  220  includes thickened and rounded corners and side walls  670 L,  670 U that are somewhat thinner in certain areas than the nominal wall thickness.  
         [0158]    More specifically, the upper tree-engaging brace  220 , as shown in FIG. 15, has a base wall  570 , a lower side wall  670 L, an upper side wall  670 U, and a top wall  770 . In one embodiment, the width of the base wall  570  may be between 1.23 and 1.27 inches (1.25 inches, preferably) and the total height of the upper brace  220  may be between 0.98 and 1.02 inches (1 inch, preferably). In this aspect, the width-to-height ratio for the upper brace  220  in this embodiment ranges from about 1.2-to-1 to about 1.3-to-1 (preferably, 1.25-to-1). The opposing ends of the base wall  570  extend about one eighth of an inch beyond the side walls  670 L,  670 U on both sides. Likewise, the opposing ends of the top wall  770  extend about one eighth of an inch beyond the side walls  670 L,  670 U on both sides.  
         [0159]    The top wall  770  of the upper brace  220  is somewhat arch-shaped in cross section, having a top surface that is generally flat across about one-third of its total width, and gently rounded ends where the upper brace ridges  420  are located and where the top wall  770  meets the side walls  670 L,  670 U. In one embodiment, the side walls  670 L,  670 U are approximately 0.8 inches high. In this aspect, the side walls  670 L,  670 U occupy about 80% of the total height of the upper brace  220 , whereas the arch-shaped top wall  770  occupies the remaining 22% of the total height.  
         [0160]    The wall thickness of the upper brace  220  varies at different locations. In one embodiment, the thickness of the base wall  570  is between 0.08 and 0.09 inches (0.085 inches, preferably). The thickness of the lower and upper side walls  670 L,  670 U are between 0.09 and 0.11 inches (0.1 inches, preferably). In this aspect, the lower and upper side walls  670 L,  670 U are up to 1.4 times thicker (preferably, 1.2 times thicker or about 20% thicker) than the base wall  570 . Similarly, the thickness of the top wall  770  is between 0.09 and 0.11 inches (0.1 inches, preferably). In this aspect, the top wall  770  is up to 1.4 times thicker (preferably, 1.2 times thicker or about 20% thicker) than the base wall  570 .  
         [0161]    The opposing ends of the base wall  570  are formed with a thickness of between 0.08 and 0.1 inches (0.09 inches, preferably). In this embodiment, the thicker ends of the base wall  570  are up to about 11% thicker than the central portion of the base wall  570 .  
         [0162]    Like the base wall  570 , the top wall  770  has opposing ends that are thicker than the central section of the top wall  770  and wider than the thickness of the lower and upper side walls  670 L,  670 U. In one embodiment, the opposing ends of the top wall  770  are thicker and wider in the same proportions as the opposing ends of the base wall  570 .  
         [0163]    The upper brace  220  includes a series of upper brace ridges  420 , in the embodiment shown in FIG. 15, located generally along the outer surface of the opposing ends of the top wall  770 . In one embodiment, two (2) distinct upper brace ridges  420  are defined by a series of grooves formed in the top wall  770  next to each ridge  420 . While two brace ridges  420  are provided in this embodiment, any number of ridges may be suitable for a particular use. The brace ridges  420  may be randomly spaced or evenly spaced. The brace ridges  420  may have a nominal height in one embodiment of 0.02 inches and a nominal width of 0.04 inches. In this embodiment, the width-to-height ratio is approximately 2-to-1.  
         [0164]    The overall cross-sectional area of each of the upper brace  220  is approximately 0.39 square inches in one embodiment, although more or less area may be required to accommodate a particular intended use. All corners are formed with a radius.  
         [0165]    The cross members of the foot climber  210  are shown in cross section in FIGS. 16, 17, and  18 . The first cross member  215  shown in FIG. 16 is generally D-shaped and hollow in cross section, with its flat side facing toward the pole or tree  11 . The toe tube  226  shown in FIG. 17 is cylindrical lengthwise and generally circular in cross section. The heel bar  235  shown in FIG. 18 is generally D-shaped and hollow in cross section, with its flat side facing downward. The heel bar  235  includes a plurality of heel bar ridges  435  disposed along the entire length of its outer surface. The cross members  215 ,  226 ,  235  are specially shaped in cross section to provide improved strength and durability compared to simple rectangular tubing. The cross members  215 ,  226 ,  235  include rounded corners, lengthwise ridges where needed, and side walls of varying thickness for reduced weight and optimal strength.  
         [0166]    In one embodiment, the shape and dimensions of the first cross member  215  and the foot climber side rails  213 L,  213 R are the same.  
         [0167]    The first cross member  215 , as shown in FIG. 16, has a flat wall  565 , a top wall  665 T, a bottom wall  665 B, and a curved wall  765 . When assembled as part of the seat assembly  110 , the flat wall  565  of the first cross member  215  is oriented in a generally vertical direction facing the pole or tree  11 . In one embodiment, the height of the flat wall  565  may be between 1.1 and 1.15 inches (with a preferred height of 1.13 inches) and the full width of the foot climber cross member  215  may be between 1.1 and 1.15 inches (with a preferred width of 1.13 inches). In this aspect, the height-to-width ratio for the foot climber cross member  215  in this embodiment is 1-to-1. The corners between the flat wall  565  and the top and bottom walls  665 T,  665 B are formed with a radius for a smooth transition.  
         [0168]    The wall thickness of the foot climber cross member  215  varies, in one embodiment, from between 0.09 and 0.11 inches (0.1 inches, preferably) along the flat wall  565 , to between 0.08 and 0.09 inches (0.085 inches, preferably) across the top and bottom walls  665 T,  665 B, and gradually thins to between 0.05 and 0.07 inches (0.06 inches, preferably) along the curved wall  765 . In this aspect, the top and bottom walls  665 T,  665 B are up to 38% thinner (18% thinner, preferably, or about 20% thinner) than the flat wall  565 . The curved wall  765  becomes gradually thinner toward its apex or narrowest point, where the thickness is between 45% and 78% (60% preferably) of the thickness of the flat wall  565 .  
         [0169]    The walls of the foot climber cross member  215  do not include ridges in the embodiment shown in FIG. 16, but the addition of ridges for improved strength and other characteristics is contemplated.  
         [0170]    The overall cross-sectional area of the foot climber cross member  215  is approximately 0.31 square inches in one embodiment, although more or less area may be required to accommodate a particular intended use. All corners are formed with a radius.  
         [0171]    The toe tube  226 , as shown in FIG. 17, is a cylindrical pipe having in one embodiment an outside diameter of between 0.98 and 1.02 inches (one inch, preferably) and a wall thickness of between 0.05 and 0.07 inches (0.06 inches, preferably). The overall cross-sectional area of the toe tube  226  is approximately 0.18 square inches in one embodiment, although more or less area may be required to accommodate a particular intended use.  
         [0172]    The heel bar  235 , as shown in FIG. 18, has a flat wall  585  and a curved wall  785 . A series of heel bar ridges  435  are formed along the outer surface of the curved wall  785 . When assembled as part of the foot climber  210 , the flat wall  585  of the heel bar  335  is oriented in a generally vertical direction, facing downward. In one embodiment, the width of the flat wall  585  may be between 0.98 and 1.02 inches (1 inch, preferably) and the overall height of the heel bar  235  may be between 0.8 and 0.83 inches (0.81 inches, preferably). In this aspect, the height-to-width ratio for the heel bar  235  in this embodiment ranges from about 1.18-to-1 to about 1.28-to-1 (with a preferred ratio of 1.23-to-1). The corners between the flat wall  585  and the curved wall  785  are formed with a radius for a smooth transition.  
         [0173]    The wall thickness of the heel bar  235  varies, in one embodiment, in different areas. The thickness of the flat wall  585  in one embodiment is between 0.07 and 0.08 inches (0.075 inches, preferably). The thickness of the curved wall  785  begins, near its corners with the flat wall  585 , at a thickness of between 0.07 and 0.09 inches (0.08 inches, preferably), and gradually thickens toward the apex to between 0.09 and 0.11 inches (0.1 inches, preferably). In this aspect, the curved wall  785  begins at a thickness which is up to 29% thicker (7% thicker, preferably, or about 10% thicker) than the flat wall  585 . Then, the curved wall  785  becomes gradually thicker toward its apex or thickest point, where the thickness is between 1.3 and 1.6 times thicker (preferably, 1.33 times thicker or about 30 percent thicker) than the thickness of the flat wall  585 .  
         [0174]    The heel bar  235  includes a series of heel bar ridges  435  in the embodiment shown in FIG. 18, located generally along the curved wall  785 . In one embodiment, a total of four (4) heel bar ridges  353  are provided, although any other number of ridges may be suitable for a particular use. The heel bar ridges  353  may be randomly spaced or evenly spaced across the outer surface of the heel bar  235 . In the embodiment shown in FIG. 18, the pair of heel bar ridges  353  located adjacent the center of the curved wall  785  are spaced approximately forty degrees apart, radially, from a center point located within the hollow core of the heel bar  235 . The next two heel bar ridges  353  are spaced approximately thirty degrees further toward the flat wall  585 . The heel bar ridges  353  may have a nominal height in one embodiment of 0.031 inches and a nominal width of 0.063 inches. In this embodiment, the width-to-height ratio is nearly 2-to-1.  
         [0175]    The overall cross-sectional area of the heel bar  235  is approximately 0.25 square inches in one embodiment, although more or less area may be required to accommodate a particular intended use. All corners are formed with a radius.  
         [0176]    Referring to FIG. 13, the foot climber  210  includes a pair of tree-engaging diagonal cleats  216 L,  216 R which, in one embodiment, are mounted to and extend diagonally from the flat wall  565  of the foot climber cross member  215  to opposing points along the flat walls  563  of the foot climber side rails  213 L,  213 R. The diagonal cleats  216 L,  216 R may be mounted to the foot climber cross member  215  and to the foot climber side rails  213 L,  213 R by welding or by any other suitably strong and durable means of attachment.  
         [0177]    [0177]FIG. 26 includes a cross section of the right diagonal cleat  216 R, along with other views of the diagonal cleats  216 L,  216 R. The diagonal cleats  216 L,  216 R, which are generally L-shaped in cross section, include rounded corners, lengthwise ridges along select locations, and side walls of varying thickness for reduced weight and optimal strength.  
         [0178]    More specifically, the right diagonal cleat  216 R, as shown in FIG. 26, has a flat wall  566  and a side wall  666 . A series of cleat ridges  416  are formed along the outer surface of the side wall  666 . When assembled as part of the seat assembly  110 , the flat wall  566  of the right diagonal cleat  216 R is oriented in a generally horizontal direction, facing upward. In one embodiment, the width of the flat wall  566  may be between 0.98 and 1.02 inches (with a preferred height of 1 inch) and the height of the side wall  666  may be between 0.97 and 1 inch (with a preferred width of 0.98 inches). In this aspect, the height-to-width ratio for the right diagonal cleat  216 R in this embodiment is nearly 1-to-1. The single corner between the flat wall  566  and the side walls  666  is formed with a radius for a smooth transition.  
         [0179]    The wall thickness of the right diagonal cleat  216 R varies, in one embodiment, from between 0.08 and 0.1 inches (0.09 inches, preferably) along the flat wall  566 , to between 0.12 and 0.14 inches (0.13 inches, preferably) along the side wall  666 . In this aspect, the side wall  666  is between 1.2 and 1.8 times (preferably, 1.4 times or about one-and-a-half times) thicker than the flat wall  566 .  
         [0180]    The side wall  666  includes a straight section and a curved section. The cleat ridges  416  are located along the curved section in the embodiment shown in FIG. 26. The thickness of the curved section of the side wall  666  gradually increases toward the free end, from the nominal thickness of 0.13 inches to 0.19 inches at the free end. In this aspect, the free end of the curved section of the side wall  666  is about 1.5 times thicker than the straight section of the side wall  666 .  
         [0181]    In one embodiment, three (3) cleat ridges  416  are provided on the curved section of the side wall  666 , although any number of ridges may be suitable for a particular use. The cleat ridges  416  may be randomly spaced or evenly spaced. The cleat ridges  416  may have a nominal height in one embodiment of 0.031 inches and a nominal width of 0.063 inches. In this embodiment, the width-to-height ratio is about 2-to-1.  
         [0182]    The overall cross-sectional area of each of the right diagonal cleat  216 R is approximately 0.23 square inches in one embodiment, although more or less area may be required to accommodate a particular intended use. All corners are formed with a radius. The left diagonal cleat  216 L has the same range of dimensions and ratios and, in a preferred embodiment, is a mirror image of the right diagonal cleat  216 R. When assembled as part of the seat assembly  110 , the flat wall of the left diagonal cleat  216 L is oriented in a generally horizontal direction, facing upward.  
         [0183]    The cleat ridges  416  are positioned along the curved section of the side wall  666  where they will frictionally engage the surface of the tree  11  or pole during use. Different configurations, shapes, and sizes of the cleat ridges  416  may be suitable for a particular application. Use of the assembly  10  on a smooth utility pole, for example, may require more cleat ridges  416 , formed at a greater height, and/or with sharper edges than shown for an assembly  10  which is intended for use on a rougher tree trunk. The suggested dimensions given, for one embodiment, represent a preferred configuration for an assembly  10  that is particularly well-suited for engaging any of a variety of trees. Because other uses are contemplated, other dimensions and configurations may be appropriately developed that are within the scope of the invention disclosed.  
         [0184]    The foot climber brace ridges  420  on the upper brace  220  and the cleat ridges  416  on the diagonal cleats  216 L,  216 R press into opposing sides of the pole or tree  11 . The wall thickness is increased at locations where the ridges  420 ,  416  are part of the upper brace  220  and the diagonal cleats  216 L,  216 R, respectively.  
         [0185]    It should be noted that the brace ridges  420 , the cleat ridges  416 , and any other ridges disclosed herein may be shaped in the form of raised ridges projecting above the nominal outer surface of a component or, alternatively, shaped in the form of depressed grooves below the nominal outer surface. It should be understood that any method of forming the ridges lies within the scope of the invention.  
         [0186]    The grip of the opposing ridges  420 ,  416  (as depicted, generally, using the seat assembly  110  in FIG. 11A), in one aspect of the invention, allows the foot climber  210  to frictionally engage the pole or tree  11 . The weight of a hunter  43  upon the foot climber  210 , for example, exerts an eccentric downward force with respect to the tree  11 . The foot climber  210  is generally cantilevered when in use. The hunter&#39;s weight on the foot climber  210  causes the brace ridges  420  on the upper brace  220  to press into the side of the pole or tree  11  and, simultaneously, the cleat ridges  416  on the diagonal cleats  216 L,  216 R to press into the opposite side of the pole or tree  11 .  
         [0187]    In another aspect, the gripping ridges  420 ,  416  also provide a grip on the tree  11  that is more quickly and easily releasable when compared to other, more invasive gripping means such as serrated edges or spikes that pierce the tree or pole. Prompt release is an advantage because it reduces the work to be done by the user during the climbing process. The task of repeatedly engaging and releasing the foot climber  210  from the tree  11  while climbing or descending requires constant attention by the user.  
       Climbing  
       [0188]    When the user reaches a columnar structure such as a pole or tree  11  selected for climbing, the climbing assembly  10  can be expanded for use. Pulling on the third cross member  135  will cause the third frame section  32  and the second frame section  23  to become extended out of the first side rails  113 L,  113 R to their full extent as shown in FIG. 2. The upper tree-engaging brace  120  is then removed from the first side rails  113 L,  113 R by removing the locking bolts  121 L,  121 R, respectively. The climbing assembly is then moved into position so that the first side rails  113 L,  113 R straddle the tree  11  and the diagonal cleats  116 L,  116 R are immediately adjacent the trunk of the tree  11 . Then, the upper brace  120  is attached to the first side rails  113 L,  113 R by selecting holes  19 L,  19 R that place the upper brace  120  adjacent to the trunk of the tree  11  such that the upper brace  120  fits closely but loosely about the tree.  
         [0189]    To climb a tree  11  after both the seat assembly  110  and the foot climber  210  are assembled around the tree  11  in a fully-extended position and resting on the ground, the hunter  43  steps through the second frame section  23  of the climbing assembly  10  and straddles the flexible seat  38 . The hunter  43  then slides the seat assembly  110  up the tree by grasping and lifting the first side rails  113 L,  113 R. The hunter  43  then allows the seat assembly  110  to tilt downward into an angular position, thereby causing the diagonal cleats  116 L,  116 R to bite into the front side of the tree  11  and the brace ridges  220  on the upper brace  120  to bite into the back side of the tree  11 . With the seat assembly  110  thus secured in position on the tree  11 , the hunter  43  is free to maneuver the foot climber  210 .  
         [0190]    To lift the foot climber  210 , the hunter  43  places the heels of his shoes on the heel bar  235  and inserts the toes of his shoes under the toe tube  226  and, while grasping the secured seat assembly  110 , lifts the foot climber  210  by bending his knees and raising his legs. In the absence of weight upon the foot climber  210 , it will slide up the tree. When the foot climber  210  has been raised to the desired height, the hunter  43  then allows the foot climber  210  to tilt downward into an angular position, thereby causing the foot climber diagonal cleats  216  to bite into the front side of the tree  11  and the brace ridges  440  on the foot climber brace  220  to bite into the back side of the tree  11 . With the foot climber  210  thus secured in position on the tree  11 , the hunter  43  can stand with all his weight on the foot climber  210  and lift the seat assembly  110  up to the next desired height.  
         [0191]    Thus, in alternating fashion, the hunter  43  first supports his weight (in a somewhat crouching position) on the foot climber  210  and lifts the freely-sliding seat assembly  110  up the tree until he is standing nearly upright. Then, the hunter  43  supports his weight on the secured seat assembly  110  and lifts the freely-sliding foot climber  210  up the tree with his feet until he is once again in a somewhat crouching position. This process is repeated in alternating fashion until the hunter  43  is at the desired height above the ground.  
         [0192]    With both the hunter support apparatus  110  and the foot climber assembly  210  secured in place around the tree  11 , the hunter  43  can sit on the first cross member  115 , lift his legs from around the flexible seat  38 , turn his body around, and transfer his body weight into the flexible seat  38 . When the hunter  43  desires to leave the tree  11 , the steps described above are generally performed in reverse order until the hunter  43  reaches the ground.  
         [0193]    While in the seated position, as depicted in FIG. 1, with the hunter&#39;s shoulders or head resting against the first cross member  115 , his knees resting on the second cross member  126 , and his feet resting on the third cross member  135 , the center of gravity of the hunter  43  is well away from the center of the tree  11  and below the point where the diagonal cleats  116 L,  116 R bite into the surface of the tree  11 . The position of the hunter  43 , thus, provides a strong lever action, causing the cleat ridges  316  on the diagonal cleats  116 L,  116 R and the brace ridges  320  on the upper brace  120  to grip the tree firmly and securely, keeping the seat assembly  110  from slipping down the tree.  
         [0194]    The relatively low seating position provided by the flexible seat  38  and seat assembly  110  also gives hunters, in particular, an advantage when aiming a rifle. When seated, the hunter can use his or her knees, as well as the back and side rails, to execute a steady shot. Providing a resting aim can increase the hunter&#39;s effective range, thereby allowing the hunter to accurately hunt a much wider area when using the climbing assembly  10  of the present invention. These same advantages will assist naturalists and photographers.  
         [0195]    The flexible seat  38 , sturdy side rails, and diagonal cleats  116 L,  116 R also provide stability for the user so that he or she can enjoy a nearly 360-degree view of the surroundings. The diagonal mounting of the diagonal cleats  116 L,  116 R provides three-point contact with the tree  11  and thus prevents tilting of the hunter support apparatus  110  about its longitudinal axis and, further, prevents the seat assembly  110  from rotating about the tree  11  under the weight of the hunter  43 . The seat assembly  110  may also include an adjustable cinch strap (not shown) to wrap around the trunk of the tree for additional stability. The adjustable cinch strap may be attached, using S-shaped hooks or the like, to the holes  219 L,  219 R nearest the free ends of the first side rails  113 L,  113 R. Once in place around the tree  11 , the cinch strap can be tightened until snug, frictionally engaging the surface of the tree  11  or pole and, thus, providing additional rotational stability. The cinch strap may also be used to strap the foot climber  210  to the seat assembly  110  when carrying the climbing assembly  10  to another location.  
         [0196]    The flexible seat  38  comfortably supports the hunter  43  in a lounging position where the hunter  43  can remain motionless and quiet for long periods of time so as not to draw the attention of game animals passing through the area. The lowered configuration of the flexible seat  38  positions the hunter  43  between the second side rails  124 L,  124 R, as shown in FIG. 1. Thus, the second side rails  124 L,  124 R provide arm rests for the hunter  43  and also prevent him from falling sideways out of the seat assembly  110 , even if he were to fall asleep. However, the hunter  43  is free to aim his weapon through a large range of angles without a major change of body position. Also, the first cross member  115  supports the hunter&#39;s shoulders against the recoil of his rifle.  
         [0197]    Of course, the climbing assembly  10  offers the advantage of hunting from a high elevation. The hunter or other user can sit at a height that is sufficient to prevent detection by wildlife with keen eyesight and an acute sense of smell. Especially in the winter when the foliage does not provide cover, the climbing assembly  10  offers a way to climb to a concealed location.  
         [0198]    Preferably, the load-bearing components of the seat assembly  110  and foot climber  210  are constructed of heavy-duty extruded aluminum to form strong yet lightweight components. The components of the present invention may be constructed of other metals, plastics, composite materials, or other material of suitable strength and durability without departing from the scope or spirit of the present invention.  
         [0199]    While this invention has been described in detail with particular reference to a preferred embodiment thereof, it will be understood by those skilled in the art that variations and modifications may be made without departing from the spirit and scope of the invention as described herein.