Abstract:
Knockdown furniture including a table comprising flat, interlocking, planar parts assembled or disassembled without tools or fasteners. Planar legs oriented in radially, spaced apart, mutually abutting relation upon erection, compressively grasp and support an elevated top. Each leg comprises a foot touching the ground, an integral, upwardly, outwardly diverging arm for grasping the top, a vertically upright protrusion of gradually decreasing width, and a junction region from which these parts emanate. A planar lock includes slots through which the protrusions pass when the furniture is press-fitted together. Lock notches aligned with the slots concurrently engage the arms. Each protrusion decreases in width, with the outside of each protrusion comprising a ramp, and the inside forming an elongated, vertical edge. The wedging action resulting from slot-to-ramp engagement locks the legs together, with the complimentary protrusion edges firmly abutting one another and with the top compressively grasped by the arms.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]    This application is a divisional application based upon my prior pending application Ser. No. 09/912,718, filed Jul. 26, 2001 by applicant, Franciscus P. Bart, and entitled “Jointed Interlocking Knock-Down Furniture.” 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    I. Field of the Invention  
           [0003]    The present invention relates generally to modular furniture items. More particularly, my invention relates to portable, knockdown furniture items comprising a plurality of flat, readily transportable parts that can be easily erected or disassembled without special tools.  
           [0004]    II. Description of the Prior Art  
           [0005]    The prior art recognizes that modular, knockdown furniture items have a variety of useful applications. One advantage of modular construction is that the device parts may be shipped in a flat configuration in disassembled form. The user can then simply fit the parts together to create a piece of furniture. With a variety of parts of different shapes and sizes, the user can create different artistic effects as well as different furniture forms. Once at the application site, the parts should fit together reliably and easily to facilitate erection.  
           [0006]    Furniture articles that can be folded or disassembled into individual, flat constituent parts can more easily be stored and transported. When unassembled and piled together, flat parts will occupy a minimum amount of storage space. Hunters, campers, and other outdoor users, for example, prefer knockdown items, as they can easily be stored, hauled to the campsite, and erected for use in a short period of time. The user can easily put the items together, as long as simplicity of design is maintained, and especially where the design omits irregular or complex parts. Favorable designs should comprise parts that may be quickly and easily assembled without the use of hand tools. The requirement of special tools is especially disadvantageous. Furniture items comprising a minimum of parts that fit together reliably without the necessity to read or study manuals or other documentation are preferred.  
           [0007]    One problem with modular furniture is that sturdy, assembled structures are difficult to erect with parts that are easily assembled and disassembled. Some prior art knockdown articles have recognizable disadvantages. Some devices comprise too many parts, and sometimes tools or special fasteners are required for erection. Some knockdown devices comprise intricate parts that are too expensive. Some folding furniture devices require assembly by relatively skilled personnel. Some knockdown articles cannot withstand heavy use, and they will not reliably support heavy loads. Known devices that do not require fasteners and/or hand tools for assembly or disassembly lack the mechanical durability and dependability required for commercial success.  
           [0008]    The most reliable and durable prior art knockdown furniture items have all required tools or multiple fasteners. An easily assembled knockdown arrangement that consists only of flat pieces, and which can be hand-assembled into a durable and powerful furniture article would be highly desirable.  
         SUMMARY OF THE INVENTION  
         [0009]    All embodiments of my knockdown furniture comprise a plurality of flat, planar parts that can be easily erected without hand tools or fasteners. The assembled items are easily disassembled, and the lightweight, flat parts can be quickly separated and stored for transportation.  
           [0010]    Each furniture item comprises a plurality of identical, generally C-shaped legs, a relatively large, flat top supported by the legs, and a planar lock in the form of an intermediate surface disposed by the legs below the top. The top may be circular, or it may be in the form of a regular polygon. The lock may be shaped similarly, but preferably, it is smaller than the top. Each leg is generally C-shaped, comprising a foot for touching the ground or floor, an upper arm for grasping the top, and an intermediate section that is oriented generally perpendicularly relative to the ground when assembly is completed.  
           [0011]    Special slots are defined in the lock for receiving the legs, which are first rotated during assembly until the legs are vertical, with their midsections confined and captivated within the lock slots. Importantly, each leg intermediate section varies in width. The outside of the leg intermediate region comprises a ramp. The inside of the same area forms a complementary leg edge. The distance between the ramp&#39;s structure and the complementary edges varies, to enable a wedging action in response to the lock. The legs assume a position in assembly wherein they are radially spaced apart, with the inner, complementary leg edges of each leg midsection abutting one another. At the same time, the leg&#39;s ramps contact the outermost ends of the lock slots, in which the legs are inserted and confined. Once the legs are installed, the lock can be pressed downwardly to firmly, compressively secure the legs and the rest of the parts together. The leg arms have hooks that firmly grasp the top in assembly.  
           [0012]    This invention provides a knock down furniture design comprising a plurality of flat, planar parts that can be fitted together without tools or fasteners. Once assembled, the device functions durably and dependably until disassembled as desired.  
           [0013]    Thus, a basic object of my invention is to provide a knockdown furniture item comprised only of flat, interfitting parts that can be assembled without tools or fasteners.  
           [0014]    Another basic object is to provide a robust furniture item that can be easily stored and transported.  
           [0015]    A fundamental object is to provide a furniture item of the character described that can be user-erected without tools.  
           [0016]    Similarly, it is a broad object of my invention to provide a knockdown furniture item comprising a minimal number of parts.  
           [0017]    Yet another important object is to provide a furniture item of the character described that can be deployed in the form of a table, chair or other desired furniture article.  
           [0018]    Another object is to provide a stool, table or similar furniture article that can be stored in a completely flat orientation.  
           [0019]    A similar object is to minimize storage and transportation volume requirements.  
           [0020]    Another important object is to provide a similar furniture article of the character described which is lightweight and sturdy.  
           [0021]    A still further object is to provide a modular knockdown furniture item such as a table or chair whose components can be sold in an easily assembled kit form.  
           [0022]    Yet, another broad object is to provide an article of furniture comprising generally planar parts that are made of sheet or board material.  
           [0023]    Another important object is to enable the user to quickly erect a durable and sturdy furniture article without special training.  
           [0024]    A similar object is to enable the user to quickly erect a sturdy and durable furniture item without the need for referencing complex manuals or instructions.  
           [0025]    A fundamental object is to provide a modular, knockdown furniture construction of the character described comprised of parts that may be manufactured from plastic, corrugated material, cardboard, plywood or the like.  
           [0026]    These and other objects and advantages of the present invention, along with features of novelty appurtenant thereto, will appear or become apparent in the course of the following descriptive sections.  
         BRIEF DESCRIPTION OF THE DRAWINGS  
         [0027]    In the following drawings, which form a part of the specification and which are to be construed in conjunction therewith, and in which like reference numerals have been employed throughout wherever possible to indicate like parts in the various views:  
           [0028]    [0028]FIG. 1 is a frontal isometric perspective view of a preferred embodiment of my invention, comprising a knockdown table with an octagonal top;  
           [0029]    [0029]FIG. 2 is a top plan view thereof;  
           [0030]    [0030]FIG. 3 is a front plan view thereof;  
           [0031]    [0031]FIG. 4 is an exploded isometric view thereof;  
           [0032]    [0032]FIG. 5 is a frontal isometric view of a partially erected assembly;  
           [0033]    [0033]FIG. 6 is a front elevational view of the partially erected assembly of FIG. 5, with the legs in a position after initial assembly;  
           [0034]    [0034]FIG. 7 is a top plan view of the assembly of FIG. 6;  
           [0035]    [0035]FIG. 8 is a frontal isometeric view of the table, with the legs fully inserted and rotated into a potential top-grasping configuration before reaching the final assembled orientation;  
           [0036]    [0036]FIG. 9 is an exploded plan view of the individual, unassembled parts of the first embodiment conveniently, flatly disposed in a position for transportation or assembly;  
           [0037]    [0037]FIG. 10 is an enlarged, front plan view of the preferred embodiment, showing it partially assembled/disassembled;  
           [0038]    [0038]FIG. 11 is a top plan view of the preferred embodiment taken generally along lines  11 - 11  in FIG. 10;  
           [0039]    [0039]FIG. 12 is an enlarged, fragmentary sectional view of the preferred embodiment based generally upon circled region  12  of FIG. 11;  
           [0040]    [0040]FIG. 13 is a frontal isometric view of a second or alternative embodiment of my invention, comprising a knockdown chair or stool with a round top;  
           [0041]    [0041]FIG. 14 is a front plan view of the alternative embodiment;  
           [0042]    [0042]FIG. 15 is a top plan view of the alternative embodiment;  
           [0043]    [0043]FIG. 16 is a bottom isometric view of the alternative embodiment;  
           [0044]    [0044]FIG. 17 is an enlarged, partially assembled/disassembled, front plan view of the alternative embodiment;  
           [0045]    [0045]FIG. 18 is an enlarged, fragmentary sectional view taken generally along line  1818  of FIG. 17;  
           [0046]    [0046]FIG. 19 is an enlarged, partially exploded, isometeric view of the alternative embodiment in a partially assembled/disassembled orientation;  
           [0047]    [0047]FIG. 20 is a fully exploded, isometeric view of the alternative embodiment;  
           [0048]    [0048]FIG. 21 is an exploded plan view of the individual, unassembled parts of the alternative embodiment conveniently with the components flatly disposed in a position for transportation or assembly;  
           [0049]    [0049]FIG. 22 is a frontal isometric view of an embodiment of my invention, in which the lock is not penetrated by the leg&#39;s arms;  
           [0050]    [0050]FIG. 23 is a front plan view of the embodiment of FIG. 22;  
           [0051]    [0051]FIG. 24 is a top plan view;  
           [0052]    [0052]FIG. 25 is a bottom plan view; and,  
           [0053]    [0053]FIG. 26 is a greatly enlarged plan view of a leg used in it he embodiment of FIGS.  22 - 25 .  
       
    
    
     DETAILED DESCRIPTION  
       [0054]    Turning initially now to FIGS.  1 - 12  of the drawings, an alternative embodiment of my knockdown furniture invention comprises a table, generally designated by the reference numeral  30 . The preferred embodiment is seen in FIGS.  22 - 26 . Table  30  comprises a plurality of planar parts to be described later, that can all be made from planar material such as cardboard, fiber board, corrugated plywood or the like. The parts may be assembled or disassembled, as described later, without hand tools, and when assembled, a rigid and dependable furniture item is created. No special fasteners are required.  
         [0055]    Table  30  comprises the three main components laid out for convenient viewing in FIG. 9. These are legs, generally designated by the reference numeral  32 , a planar, generally polygonal top, broadly designated by the reference numeral  34 , and an intermediate, planar lock, generally designated by the reference numeral  36 . When the foregoing parts are assembled, as described in further detail hereinafter, the legs are inserted through the slot structure  39  (FIG. 4) defined in the lock  36 , and they reach upwardly and engage and support top  34 . Once they are inserted and properly juxtapositioned by the assembler, the lock  36  is pressed downwardly to secure the legs in radially spaced-apart orientation, firmly grasping the top and reinforcing the leg structure. As hereinafter further described, the furniture item (i.e., table  30 ) results. It is adapted to be deployed upon a firm, planar, supporting surface such as floor  37  (FIG. 1). When assembled, the table legs  32  are firmly pressed against one another in an edgewise fashion, with the tabletop  34  disposed vertically above the lock  36 . When properly deployed, lock  36  will be parallel with top  34 . The exposed, upper supporting surface  35  of table top  34  presents a strong and durable support for a variety of items, including picnic supplies, silverware, plates, pots and pans and the like.  
         [0056]    In table embodiment  30 , the top  34  is preferably octagonal, comprising eight symmetrical edges  40  (FIG. 2) that are radially spaced apart about the center of table surface  35 . This configuration is but one of many that may be adopted. For example, the top  34  may be round, triangular, hexagonal, or square. It may assume the shape of any regular polygon. Where legs of varying configurations are allowed, then the top may assume a rectangular shape, or even irregular shapes, resembling trapezoids, truncated cones, semicircles and/or the like. Preferably, the legs form a symmetrical array, placed radially about the structure. Preferably, there are a number of legs  32  at least equal to three, and preferably equal to an integer fraction of the number of topsides. For example, where an octagonal top  34  is chosen, eight-table sides result, and eight divided by the integer two yields four legs. As will become apparent hereinafter, the number of legs could equal the number of tabletop sides, particularly with a square top. Preferably, the design contemplates one leg  32  for each two tabletop sides.  
         [0057]    The preferred legs  32  are all planar (i.e., for example, each leg is identical), and preferably, in a typical package of components, sold as a kit. With primary reference directed to FIGS. 4, 5,  9 , and  10 , the legs comprise a bottom foot  46 , an upper arm  50 , and an integral midsection  48 . Each foot  46  comprises a terminal bottom edge  49  (FIG. 5) adapted to be disposed upon a supporting surface  37  (FIG. 1) when the assembly is constructed. Foot  46  upwardly transitions to midsection  48  (FIG. 4). The outer edge  51  (FIG. 4) of each foot meets the supporting ledge  52  (FIGS. 4, 5) formed on the outside of midsection  48 . A step-like, stair-shaped wedging region  53  is formed on the outside of the legs, spaced apart from the specially configured, complimentary inner edges  54  (FIG. 9) of each midsection  48 . Importantly, the width of the leg across the intermediate portions  48  varies. In other words, the distance between the inner edge  54  and the opposite, outer wedging region  53  preferably increases as one moves downwardly. As explained later, this facilitates a locking action as the lock is pressed into position.  
         [0058]    Each arm  50  integrally extends angularly, upwardly and outwardly from midsection  48  (i.e., FIG. 10). The inner, upper arm edges  58  and  59 , and upper, supporting ledge  60  (FIG. 8) transition away from special edge  54  of the midsection  48 . The lower, outer edge  61  of the arms is substantially straight. As best seen in FIG. 5, the midsection&#39;s wedging region  53  comprises an angled edge  62  (FIG. 5) that adjoins arm upper edge  61  and raised, projecting region  53  (FIG. 5). Region  53  comprises a first ramp  67  (FIG. 8) and a second ramp  69  (FIG. 5). Ramp  67  adjoins angled midsection edge  62 . Ramp  69  adjoins ramp  67  and ledge  52  (FIG. 5). Region  53  effectively causes the width across the leg midsection to vary, i.e., the width between edges  54  and  62  is less than the width between edge  54  and ramps  67  or  69 . The lock wedges the parts together as it is pressed downwardly, with the leg midsection captivated within the lock slots described later. In other words, in assembly, the legs are juxtapositioned between the orientations of FIGS. 5 and 10; FIG. 5 shows the lock partly installed upon the loose legs and FIG. 10 shows the firm leg alignment maintained by the lock after it has been pressed into place.  
         [0059]    The upper arm  50  of each leg  32  terminates in a generally C-shaped hook  70  (FIGS. 5, 8,  10 ) that projects from exposed ledge  60  of the arm. When assembled, the arm ledge  60  will support the tabletop  34  previously described, as the various table edges  40  can be fitted within channels  72  (FIGS. 8, 10) so the arms support the tabletop. The upper ledges  60  of each leg are parallel with ledges  52  (FIG. 4) that support the lock  36 . Hook  70  comprises an inwardly projecting channel  72  that receives edges of the tabletop upon assembly. The channel  72  results from the generally C-shaped terminus  73  at the top of each leg&#39;s upper arms  50 . Channels  72  (FIG. 8) will be arranged symmetrically, in a radially spaced apart configuration conforming to the placement of the legs upon assembly. Upon proper assembly, the exposed upper surface  74  (FIGS. 8, 10,  11 ) of each terminus will be oriented parallel with ledges  52  and  60  previously described, with adjoining vertical surface  75  (FIG. 10) oriented perpendicularly.  
         [0060]    The lock  36  is best addressed with concurrent reference to FIGS. 4, 9,  11 , and  12 . It will be observed that the generally planar lock is flat and square. Its shape is not as important as the fact that it contains an internal, central slot structure  39 , which is symmetrical. With four legs, it is preferably in the form of a cross, with one individual slot to receive each leg. In this embodiment, four individual radially spaced apart slots  80  (FIG. 4) are defined in the lock  36 . The lock  36  has a plurality of symmetrical sides  81  (FIG. 9) forming, in this instance, a square shape. The shape can be different, as apparent to those with skill in the art. The number of slots preferably equals the number of legs to be used. In the best mode of this embodiment, the four, individual radially spaced-apart slots  80  meet at the center  82  of the lock, and the outermost slot ends project towards the lock corners. The slots are dimensioned carefully to frictionally and firmly receive and lock the legs. The distance from a slot end  83  to the slot center  82  (FIG. 9) roughly approximates the width of the leg midsection or wedging region as measured between inner edge  54  (i.e., FIGS. 4, 5,  9 ) and the ramps  67 ,  69  (FIGS. 5, 10).  
         [0061]    Proper dimensioning of the legs and the lock slots is important. As best seen in FIGS. 11 and 12, the leg midsection&#39;s inner edges  54  are preferably stepped, comprising a notch  90  and a projection  91 . When the legs are compressed together in the assembled shape, the notch of one leg abuts the notch of the others, forming the arrangement of FIG. 12. However, the inner edges of the legs could be designed differently. For example, each could be shaped like a pointed arrow. Importantly, the critical fitting distance between one leg projection  91  (FIG. 12) and the outer end  83  of a corresponding slot has been designated by reference numeral  85  (FIG. 12). This distance  85  is preferably equal to the width between inner edge  54  and ramp  69 .  
         [0062]    The legs are thus bound together in frictional, compressive abutting relation as in FIG. 12, by compressive action of the lock  36  as it is pressed down over the legs during assembly. The variable width midsection region (i.e., the leg width between ramps  67 , and edge  54 ) is captivated within lock slots of finite length; as the lock is pressed downwardly, with the legs properly oriented, action of the ramps  67 ,  69  sliding against the outermost limits of the lock slots results in compression. The legs are compressed slightly, as they are firmly drawn together by the lock. At the same time, the inner edges  54  of each leg mutually abut one another (FIG. 12). The various projections  91  (FIG. 12) abut in the mutually facing notches  90  to form a stable, radially interlocking structure. The compressed legs will remain stable in this radially interlocking arrangement, with predetermined compressive forces from the properly mounted lock  36  maintaining all the parts together.  
         [0063]    Assembly:  
         [0064]    Referring to FIG. 9, the flat pieces should be recognized, and laid out in a flat, symmetrical arrangement prior to assembly. A prudent assembler will be cognizant of the preferred, target configuration seen in FIG. 1. As seen in FIG. 6, the arms  50  of each leg are first thrust into the various slots  80  of the planar lock  36 , and preferably, their generally radially spaced-apart target orientation is preserved. As the legs reach upwardly and are positioned vertically, their hooks  70  may engage the tabletop  34 . As the pertinent tabletop edges  40  are firmly received within the channels  72  (FIG. 10), alignment begins. The width of the leg&#39;s midsection between wedging region  53  (i.e., ramp edge  67 ,  69 ) and inner edge  54  increases from top to bottom. The legs may first be arranged in a generally radially spaced apart, vertical orientation as in FIG. 4. Then the lock  36  is “installed.” Essentially, the legs are first thrust within the lock slots  80  and then rotated about their midsections to transform them between the orientations depicted in FIGS. 5 and 10. Once the legs are rotated to assume the desired orientation wherein they grasp top  34 , the lock  36  may be gently pressed downwardly, until resting upon ledges  52  (FIG. 5) and forming the stable assembly. This locks or “wedges” the parts into position with its slot ends  83  (FIG. 9) being wedged against the ramping surfaces  69  (FIG. 5) defined in the leg midsections. Once the lock  36  is pressed downwardly until it firmly rests upon the previously described leg ledges  52  (FIG. 4), assembly is completed, and the arrangement will remain stable and fixed.  
         [0065]    Alternative Embodiment:  
         [0066]    An alternative embodiment (i.e., the second embodiment), seen in FIGS.  13 - 21  of the drawings, comprises a chair  130 . Alternatively, it can be used as a stool, a table, or a shelf Chair  130  (FIGS. 20, 21) comprises a plurality of legs  132 , a preferably circular top  134 , and a preferably circular lock  136 . In this embodiment, the lock is sized and configured somewhat like the top  134 . As before, when the aforementioned planar parts are correctly assembled, a strong and dependable structure results.  
         [0067]    Each leg  132  (FIG. 20) is identical. With primary reference directed to FIGS. 16, 20, and  21 , the legs comprise a bottom foot  146 , an upper arm  150 , and an integral midsection  148 . As before, a step-like, stair-shaped wedging region  153  (FIG. 21) is formed in the midsection at the angular vertice formed by foot  146  and arm  150 . Each arm  150  integrally extends angularly upwardly and outwardly from each corresponding midsection  148 . An upper supporting ledge  160  supports the top  134  after assembly. The lower ledge  154  supports the lock  136  in the same manner as that previously described.  
         [0068]    As best seen in FIG. 21, the leg midsections all comprise a wedging region  153  having a pair of angled ramp portions that function, as described previously, when the legs are compressed within the lock&#39;s slot structure  139 . As before, each leg  132  terminates at its top in a generally C-shaped hook  170  that captivates the top  134  upon assembly. The lock&#39;s slot structure  139 , is symmetrical, in the form of a cross, and comprises four individual radially spaced apart slots  180  (FIG. 21) to fit the four legs. These slots are dimensioned carefully to frictionally and firmly receive and lock the legs as previously described. Assembly also occurs as previously described.  
         [0069]    Preferred Embodiment:  
         [0070]    A preferred embodiment is seen in FIGS.  22 - 26  of the drawings. A furniture item  200 , nominally shaped like a table, can also be used as a stool or shelf Item  200  comprises a plurality of similar, flat legs  202 , a preferably circular top  204 , and a preferably circular lock  206  that has a smaller diameter than tabletop  204 . Of course, top  204  and lock  206  can be shaped or dimensioned differently, as will be appreciated by those skilled in the art. In this embodiment, the lock is also sized and configured somewhat like the top  204 . Once again, when the aforementioned planar parts are correctly assembled, a strong and dependable structure results. However, the lock  206  is coupled to the legs through a different arrangement. While the indicated structure is slightly different, principles of operation remain largely the same.  
         [0071]    Each identical leg  202  comprises a bottom foot  208 , an upper arm  210 , and a locking protrusion  212  (i.e., FIG. 22), all of which integrally emanate from junction region  209 . A locking recess  211  is formed within protrusion region  209  above the juncture of arm  210  and protrusion  212 . As with the prior embodiments, each leg  202  terminates at its top in a generally C-shaped hook  221  (FIG. 26) that captivates the top  204  upon assembly. Unlike prior embodiments, lock  206  is not penetrated by the arms of the legs; rather, it is fitted to the abutting protrusions  212 . Each protrusion  212  defines a step-like, stair-shaped wedging region  215  that tightly fits through slot structure  218  defined in lock  206 . Each arm  210  integrally extends angularly upwardly and outwardly from the corresponding protrusion  212 . An upper supporting ledge  220  on each arm  210  jointly supports the tabletop  204  after assembly. Each locking recess  211  has a lower ledge  230 . Upon assembly, the aligned ledges  230  provide a seat that supports the lock  206  after it is forcibly pressed into place.  
         [0072]    As best seen in FIG. 26, the wedging region  215  comprises a straight, perpendicularly upwardly extending edge  222  defined on protrusion  212  that is spaced apart from and parallel with the legs&#39; elongated inner edge  225 . Inner edge  222  adjoins the upwardly extending, inclined protrusion edge  224  that functions as a ramp. Edge  224  extends upwardly to the flat protrusion top  226 . The protrusions  212  (i.e., FIG. 26) get narrower towards their tops  226 . The spaced-apart arm  210  has an inclined upper edge  228  that extends angularly upwardly from the arms&#39; lower vertical edge portion  229  (FIG. 26). The arms&#39; vertical edge portion  229  is spaced apart from and parallel with protrusion edge  222 , with a flat, lower ledge  230  defined therebetween.  
         [0073]    The lock&#39;s slot structure  218  (FIG. 22) is symmetrical, preferably in the form of a cross, for embodiments using four legs. There are four individual, radially spaced apart slots  234  (FIG. 22) to fit the four legs. These slots are dimensioned carefully to frictionally and firmly receive and lock the legs as previously described. They are dimensioned substantially the same as dimension  231  in FIG. 26 so that firm locking engagement occurs when the lock is press fitted downwardly over the abutting protrusions on the radially-aligned leg structures. When pressed downwardly, the slot structure edges  224  first penetrate slot structure  218 , and as pressure continues, the lock is frictionally snap-fitted in firm compressive engagement between aligned, coplanar legs whose protrusions  212  occupy the lock slots. The lock comes to rest upon lower ledge  230  within recess  211  (FIG. 26). Additionally, each lock  206  comprises radially spaced apart, peripheral notches  240  that are aligned with individual slots  234  (FIG. 22). In assembly, the lock notches  240  firmly receive and abut arm edges  229  (FIG. 26) previously described, to create further frictional locking forces upon assembly. The solid body region of the locks between the peripheral notches  240  and the slots  218  is wedged into recess  211 , overcoming predetermined yieldable forces from gradual tightening as the apparatus rides over incline  224  during assembly. When pressed far enough into engagement, the lock rests upon the ledge  230  provided by each leg.  
         [0074]    From the foregoing, it will be seen that this invention is one well adapted to obtain all the ends and objects herein set forth, together with other advantages which are inherent to the structure.  
         [0075]    It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.  
         [0076]    As many possible embodiments may be made of the invention without departing from the scope thereof; it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.