RELATED APPLICATION  
       [0001]    This is a continuation-in-part of my application Ser. No. 09/763,426, filed Feb. 20, 2001, and entitled Self Stabilizing System. 
     
    
     
       TECHNICAL FIELD  
         [0002]    This invention relates to a self-stabilizing structural system. It has particular but not exclusive application to a self-stabilizing and self-locking mechanism for an assembly supported on a surface by a four-based structure of legs or feet. It has particular but not exclusive application to self-stabilizing mechanisms for tables, ladders, stools, trestles, and numerous other four-footed structures, including, but not limited to, all others further identified in this document.  
         BACKGROUND INFORMATION  
         [0003]    Tables and four-footed structures in general are often subject to uneven supporting surfaces, e.g. floors, causing them to wobble to some degree. Too often the solution involves placing some other form of a shim under one of the four feet. This is an annoyance and is only a temporary solution. This is a problem that needs an effective solution.  
           [0004]    Numerous attempts have been made to solve this problem, including those solutions disclosed in the following patents:  
           [0005]    Humphreys U.S. Pat. No. 467,811;  
           [0006]    Junkunc U.S. Pat. No. 3,117,392;  
           [0007]    Whitman U.S. Pat. No. 2,787,087;  
           [0008]    Henderson U.S. Pat. No. 3,204,906;  
           [0009]    Winters U.S. Pat. No. 5,690,303;  
           [0010]    Price Australian Patent No. AU-A-36001/89.  
           [0011]    The above patents have proposed solutions for table wobble but in practice, from a stability point of view, these solutions operate similarly to a three-footed structure. Pressure placed from the top down on a corner or on a side of a table, can cause the table to become unbalanced. The proposed solutions of these patents cannot achieve the desired stability and ease of automatic self-adjustment.  
           [0012]    Other proposed solutions include those disclosed in the following patents:  
           [0013]    Balcar U.S. Pat. No. 2,835,427;  
           [0014]    Derby U.S. Pat. No. 2,890,824;  
           [0015]    Forristall U.S. Pat. No. 4,095,671.  
           [0016]    The systems of these patents are all ladder-leveling systems, with friction binding methods. They have two adjustable legs, requiring two locking mechanisms. While the ladder-type construction may work well for two-footed applications, they are not suitable for four-footed structures. One disadvantage is that one locking mechanism will generally engage before the other, thus creating an imbalance in the final settlement of the four-footed structure.  
           [0017]    Other proposed solutions, include those disclosed in the following two patents:  
           [0018]    Husted U.S. Pat. No. 2,555,036.  
           [0019]    Basile U.S. Pat. No. 3,878,918;  
           [0020]    The systems of these patents do not solve the problem, as they are ladder-type constructions that have to be manually locked or unlocked, and generally are not useable on four-footed structures.  
           [0021]    The proposed solution by Robinson, Australian Patent No. AU-A-23711/97 is another ladder-type construction. The locking mechanism releases if one leg is lifted off the ground, and further, it is unsatisfactory for a four-footed structure.  
           [0022]    Further proposed solutions of ladder type constructions are disclosed in the following patents:  
           [0023]    Hopfeld U.S. Pat. No. 3,102,606;  
           [0024]    Cook, Sr. U.S. Pat. No. 4,128,139;  
           [0025]    Studer U.S. Pat. No. 4,627,516.  
           [0026]    The systems of these patents also fall short of the desired solution, as they are ladder-types. Also, because their locking systems are incremental in nature, they will always have a slight degree of wobble if applied to a four-footed structure.  
           [0027]    The last solution considered here is a proposed improvement to a four-legged table, in Hickman, Australian Patent No. AU-A-24881/95. Hickman&#39;s proposed solution involves two identical leg assemblies that rotate in opposite directions. While this in another fine proposal in theory, it is evidently impractical in real applications.  
           [0028]    The primary object of the present invention is to provide an effective solution to the problem that will essentially eliminate all wobble.  
         BRIEF SUMMARY OF THE INVENTION  
         [0029]    The new self-stabilizing system of the invention is a solution that is effective in all aspects of operation in four-footed structures. This new invention is a built-in, self-stabilizing system that allows automatic adjustment and locking, ensuring all four feet are firmly maintained on the supporting surface. The advantages and benefits of the self-stabilizing system are evident in the unique action of a trigger foot and an adjustable foot. The adjustable foot, once locked into position, will remain locked provided that either the adjustable foot or the trigger foot remains weighted. This enables the self-stabilizing system to behave the same as a rigid four-footed structure even if the table is tilted. This feature also makes the self-stabilizing system suitable for ladders, ensuring that the system stays locked even if weight is removed from either of the two feet. It has been effectively demonstrated that the self-stabilizing system solves the problem of wobble in four-footed structures. The prototypes operate well in providing table stability, ease of use, and effectiveness. Additional benefits, features and aspects of this invention are further described in this document.  
           [0030]    The objectives of this invention are as follows:  
           [0031]    1. to establish a unique self-stabilizing system for four-footed structures that will adapt itself to even or uneven surface contours;  
           [0032]    2. to provide a system of self-stabilization utilizing a completely new technique consisting of a trigger foot, an adjustable foot, and a locking mechanism, whereby the trigger foot initiates the locking action upon the adjustable foot;  
           [0033]    3. to provide a self-stabilizing system applicable to numerous four-footed devices of variable size, shape, dimension and function;  
           [0034]    4. to provide a means whereby the locking mechanism can be adapted to, and concealed within, a wide variety of conventional support apparatus;  
           [0035]    5. to provide a self-stabilizing system where the trigger foot and the adjustable foot can have two different methods of operation: telescopic or pivoting;  
           [0036]    6. to provide two types of locking aperture mechanisms that can be applied to different needs and styles of manufacturing: the binding arm with aperture and the trigger foot with aperture;  
           [0037]    7. to provide a self-stabilizing system that can be constructed as an internal mechanism or an external mechanism;  
           [0038]    8. to provide a self-stabilizing system that can be applied to a support structure in which the trigger leg, adjustable leg, and two fixed legs are elongated;  
           [0039]    9. to provide a self-stabilizing system in which there are feet that adjust the structure and which exist within the support structure at the point of contact with the support surface;  
           [0040]    10. to provide a self-stabilizing system that produces an effectively rigid four-footed structure;  
           [0041]    11. to provide a self-stabilizing system that locks the adjustable foot in precise position relative to the exact degree of adjustment required;  
           [0042]    12. to provide a trestle stabilizing system that is robust and easy to manufacture;  
           [0043]    13. to provide a self-stabilizing system that offers numerous alternatives and methods of manufacture;  
           [0044]    14. to provide the public with a greater choice of alternatives to meet various needs, both household and commercial;  
           [0045]    15. to provide a self-stabilizing system that may also be applied to two-footed structures;  
           [0046]    16. to provide a self-stabilizing system with greater performance than the previous adjustable leveling devices;  
           [0047]    17. to provide greater safety to the public.  
           [0048]    Beyond the numerous applications, which are tremendous features, the present invention has other benefits. It is exceptionally easy to use, as the trigger foot and the adjustable foot operate automatically. For example, we will use a basic cafe table to illustrate the superior qualities of the trigger foot system. When placed on a supporting surface, the adjustable foot will extend or retract beyond the height of the fixed feet, and the trigger foot, in contacting the surface, will retract the small amount needed to initiate the locking of the adjustable foot. The mechanism is designed such that the final retraction of the trigger foot equals that of the adjustable foot after locking has been initiated and both fixed feet are already in contact with the supporting surface. The trigger foot always retracts to the same height as the fixed feet. A benefit of this self-stabilizing system is that, once the feet are locked into position, the system effectively behaves the same as a rigid four-footed structure. A benefit and dynamic aspect of this self-stabilizing system is that, if the table is bumped, dragged, pushed, or inadvertently moved, the self-stabilizing system more often than not automatically adapts itself to any variation of surface contour within the range of the adjustable foot. The only variable being that a slight rocking action may have to be applied for the adjustable foot to release its position and re-adjust.  
           [0049]    Previous systems do not have the unique combination of trigger foot, adjustable foot, and a locking mechanism initiated by a trigger foot. This self-stabilizing system can be arranged in numerous ways, creating a variety of options and uses. These and other objectives, features, advantages, and benefits of the invention will be more fully evident from the descriptions of the embodiments and the accompanying drawings.  
           [0050]    Other objects, advantages and features of the invention will become apparent from the description of the best mode set forth below, from the drawings, from the claims and from the principles that are embodied in the specific structures that are illustrated and described. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0051]    With the objectives included, further reference is made to the accompanying drawings, illustrating the numerous arrangements, combinations and methods of construction and applications of the invention, and including illustrations of preferred embodiments, wherein:  
         [0052]    [0052]FIG. 1 is a schematic bottom plan view illustrating the basic principle of support arrangement on a four-footed structure;  
         [0053]    [0053]FIG. 2 is like FIG. 1 but illustrates the basic principle of support arrangement on a four-footed structure where two sets of self-stabilizing systems are utilized;  
         [0054]    [0054]FIGS. 3 and 4 are schematic elevational views of a first embodiment illustrating the self-binding principle;  
         [0055]    [0055]FIGS. 5 and 6 are schematic elevational views of a second embodiment illustrating the two self-binding positions;  
         [0056]    [0056]FIGS. 7 through 14 are schematic diagrams illustrating the various arrangements of the crank operated binding arm mechanism;  
         [0057]    [0057]FIGS. 15 through 22 are schematic diagrams illustrating additional arrangements of the crank operated binding arm mechanism;  
         [0058]    [0058]FIGS. 23 through 30 are schematic diagrams illustrating the various arrangements of the slot operated binding arm mechanism;  
         [0059]    [0059]FIG. 31 is a sectional view through the center and adjustable foot portion of a third embodiment for a standard pedestal base, with parts shown in elevation;  
         [0060]    [0060]FIG. 32 is a plan view of the underside of a standard pedestal;  
         [0061]    [0061]FIG. 33 is a sectional view through the trigger foot portion of the third embodiment, with parts shown in elevation;  
         [0062]    [0062]FIG. 34 is a perspective view of a bracket utilized in the third embodiment;  
         [0063]    [0063]FIG. 35 is a sectional view through the center and adjustable foot portion of a fourth embodiment for a slim pedestal base, with parts shown in elevation;  
         [0064]    [0064]FIG. 36 is a plan view of the underside of a slim pedestal;  
         [0065]    [0065]FIG. 37 is a sectional view through the trigger foot portion of the fourth embodiment, with parts shown in elevation;  
         [0066]    [0066]FIG. 38 is a sectional view through the center and trigger foot portion of the fourth embodiment with parts shown in elevation;  
         [0067]    [0067]FIG. 39 illustrates the slotted actuation bar utilized in the fourth embodiment;  
         [0068]    [0068]FIG. 40 is a sectional view through the center and adjustable foot portion of a fifth embodiment for an elongated footed pedestal base, with parts shown in elevation;  
         [0069]    [0069]FIG. 41 is a sectional view through the trigger foot portion of the fifth embodiment, with parts shown in elevation;  
         [0070]    [0070]FIG. 42 is a plan view of the underside of an elongated legged pedestal incorporating the fifth embodiment;  
         [0071]    [0071]FIG. 43 illustrates the slotted actuation bar utilized in a sixth embodiment in a corner legged table;  
         [0072]    [0072]FIG. 44 is a sectional view through two legs and a cross frame of a corner legged table incorporating the sixth embodiment;  
         [0073]    [0073]FIG. 45 is a perspective view of the corner legged table shown in FIG. 44;  
         [0074]    [0074]FIG. 46 is a perspective view of a folding table incorporating a seventh embodiment;  
         [0075]    [0075]FIG. 47 is a sectional view through two legs and a cross frame of the folding table shown in FIG. 46;  
         [0076]    [0076]FIG. 48 is an elevation view illustrating the lower portion of the legs on one side of a builder&#39;s trestle incorporating an eighth embodiment;  
         [0077]    [0077]FIG. 49 is a schematic perspective view of a builder&#39;s trestle;  
         [0078]    [0078]FIG. 50 is an elevation view illustrating a ninth embodiment with parallel feet pivots;  
         [0079]    [0079]FIG. 51 is a perspective view of a table with an “inverted T base” utilizing the parallel feet pivot system shown in FIG. 50;  
         [0080]    [0080]FIG. 52 is a sectional view through the center and adjustable foot portion of a tenth embodiment including a trigger foot with aperture pedestal;  
         [0081]    [0081]FIG. 53 is a plan view of the underside of the trigger foot with aperture pedestal shown in FIG. 52;  
         [0082]    [0082]FIG. 54 is a sectional view through the trigger foot portion of the tenth embodiment;  
         [0083]    [0083]FIG. 55 is a pictorial view of a pedestal base table;  
         [0084]    [0084]FIGS. 56 through 59 are schematic diagrams illustrating the possible arrangements of the adjustable foot and trigger foot where the foot pivots are at 90 degrees to each other;  
         [0085]    [0085]FIG. 60 is a pictorial view of an embodiment of the invention which includes both a pivoting foot and a telescopic foot;  
         [0086]    [0086]FIG. 61 is a sectional view taken substantially along lines  61 - 61  of FIG. 62, such view showing an embodiment in which the trigger foot is in an arm of a base structure that is perpendicular to the arm which includes the adjustable foot; and  
         [0087]    [0087]FIG. 62 is a bottom plan view of the mechanism shown by FIG. 61. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
     Basic Support Principle for Four-Footed Structure  
       [0088]    [0088]FIG. 1 is a plan view schematic diagram illustrating the principle arrangement of a four-footed structure on a support surface. The four feet are designated  10 ,  12 ,  14 ,  16 . The adjustable foot  10  and the trigger foot  12  are located on the same side of the structure. This applies to all applications of the self-stabilizing system in a four-footed structure. Foot  14  and foot  16  are both fixed relative to the structure. This system provides stabilization only.  
       Basic Support Principle for Two Sets of Self-Stabilizing Systems  
       [0089]    [0089]FIG. 2 is a plan view schematic diagram illustrating the principle arrangement where two sets of self-stabilizing systems are utilized. The locking of adjustable foot  18  is initiated by trigger foot  20 , while the locking of adjustable foot  22  is initiated by trigger foot  24 . Two sets allow the angle of the structure, relative to the surface it sets upon, to be altered.  
       Self-Binding Principle  
       [0090]    [0090]FIGS. 3 and 4 depict a crank-arm version of three basic mechanism arrangements to illustrate the method of friction binding employed to lock the adjustable foot. A binding arm  26  is attached to a structure, not shown, by picot pin  28 . A locking rod  30  connects with the adjustable foot, not shown, and passes through an aperture  32  in the binding arm  26 . A locking rod  34  is free to slide through the aperture  32 , as indicated by arrow  36 , when the axis of the aperture  32  and the locking rod  26  are aligned. Retraction of the trigger foot (not shown) causes the trigger rod  30  to move in the direction of arrow  44 , slightly rotating the binding arm about pin  28 . This causes the axis of the aperture  32  to become non-aligned with the axis of the locking rod  34  and creates the binding action required to prevent movement of the locking rod  34  in the direction of arrow  36 .  
       Binding on Extension and Binding on Retraction  
       [0091]    [0091]FIGS. 5 and 6 depict an actuation bar version of three basic mechanism arrangements to illustrate the utilization of the two binding positions of a binding arm  38 . The binding arm  38  is attached to a structure (not shown) by a pin  40 . An actuation bar  44  is linked to a trigger foot (not shown) and is limited to linear motion by a pin  40  passing through an elongated opening  46 . Movement of the actuation bar  44  in the direction of arrow  52  will cause the binding arm  38  to slightly rotate to one of two binding positions and prevent movement of the locking rod  48  in the direction of arrow  50 . Movement of the actuation bar ______ in the direction of arrow  52  will prevent movement of the locking rod  48  in the direction of arrow  50 . These two binding positions can be utilized to provide binding on extension as well as binding on retraction of the adjustable foot.  
       Crank Actuated Binding Arm Arrangements  
       [0092]    [0092]FIGS. 7 through 14 and FIGS. 15 through 22 are schematic diagrams of several crank actuated systems. In FIGS. 7 through 22, the linear and curved arrows  54 ,  56  indicate the directions in which the components move when systems are being used. The preferred arrangement is depicted by FIG. 9. However, the invention includes all of the arrangements that we illustrated.  
       Slot Actuated Binding Arm Arrangements  
       [0093]    [0093]FIGS. 23 through 30 are schematic diagrams showing various ways that a slot actuated binding arm, a locking rod, and a trigger foot bar can be arranged. The linear and curved arrows  54 ,  56  indicate the directions in which the components move when the structure is being used. The preferred arrangement is that illustrated in FIG. 26. However, this invention includes all the arrangements that are illustrated.  
       Standard Pedestal Base  
       [0094]    The preferred mechanism for a standard pedestal base utilizes a crankoperated binding arm of the type shown by schematic FIG. 9, and herein described with reference to FIGS.  31 - 34 . FIG. 31 is a sectional view showing the pedestal center and adjustable foot housing. FIG. 32 is a plan view of the underneath side of the pedestal base. FIG. 33 is a sectional view of the trigger foot housing. FIG. 34 is a three-dimensional view of a bracket.  
         [0095]    The adjustable foot  60  pivots on a pin  62 , which is located in the pedestal base on a mounting block  64 . The adjustable foot  60  is biased to be extended by spring  66 , which is located on the locking rod  68 . The binding arm  69  pivots on a bolt  70 , which is located in the body of the pedestal base. The trigger foot  72  (FIGS. 32 and 33) pivots on a pin  74  which is located in the pedestal base on a mounting block  76 . An actuation rod  78  engages with the trigger foot  72  and has a reduced diameter at its inner end for location in the arm  82 . Spring  80  is positioned between arm  82  and a member  84  (FIGS. 32 and 34). A tab  86  on member  84  fits into the end of the spring  80 . Adjacent member  82 , the end of the spring  80  surrounds a reduced diameter portion of the rod  78  which protrudes through an opening in the arm  82 . Spring  80  biases arms  82 ,  68  into the position shown by FIG. 32. In this position, the rod  68  extends through an opening  88  in arm  68 , without there being any binding between the arm  66  and the sidewall of the opening  88 . Bracket  84  is secured to the pedestal base by a bolt  70  passing through hole  90  (FIG. 34) and by a pedestal post attachment bolt  92  passing through hole  94 . Hole or opening  96  (FIG. 34) is for the locking rod  60  to pass through. The fixed feet are not shown in either FIG. 31 or FIG. 32.  
       Slim Pedestal Base  
       [0096]    The preferred mechanism for a slim pedestal base utilizes a binding arm activated by a slotted actuation bar, as depicted in schematic FIG. 26, and is herein described with reference to FIGS. 35 through 39. FIG. 35 is a sectional view through the pedestal base showing detail of a locking mechanism and an adjustable foot  100 . FIG. 36 is a plan view showing the underside of the base. FIGS. 37 and 38 are sectional views through the trigger foot housing. FIG. 39 shows the actuation bar by itself.  
         [0097]    The adjustable foot  100  is mounted to the structure by a bracket  102  (FIG. 35) which contains pivot pin  104 . A locking rod  106  is attached to the adjustable foot  100  by a pin  108 , which is welded onto the top of the locking rod  106 . The locking rod  106  passes through an aperture  110  located in the binding arm  112 . The binding arm  112  pivots on bolt  36 , which is located in the body of the pedestal base. A pin  114  is attached to the binding arm  112 . This pin  114  engages with an angled slot  116  in the actuation bar  118 . The actuation bar  118  is located at one end by the binding arm pivot bolt  36 , which passes through slot  40 . The other end of the actuation bar  118  attaches to the trigger foot  120  by pin  122 , which is part of the actuation bar  118 . The trigger foot  120  has one round hole and one slotted hole  124  for pin  122  to reside in. The slotted hole  40  is for assembly reasons only and in operation pin  36  remains at the bottom of the slot  40 . The two springs  126 ,  128 , one ( 128 ) above the adjustable foot  100  and one ( 128 ) above the trigger foot ( 120 ), bias the feet  100 ,  120  to extend them upwardly when free to so move. The trigger foot  120  is mounted to the structure by a bracket  130  which has pivot pin  132  welded to it. The fixed feet have not been shown in either FIG. 35 or FIG. 36.  
       Pedestal with Elongated Feet  
       [0098]    The preferred mechanism for a pedestal with elongated feet utilizes a trigger leg and binding aperture system that is illustrated in FIGS.  40  to  42 . With this elongated foot design, the adjustable leg and the trigger leg pivot on pins close to the center of the pedestal. FIG. 40 is a sectional view through the center of the pedestal and the adjustable leg  134 . FIG. 41 is a sectional elevation through the center of the pedestal and the trigger leg  132 . FIG. 42 is a plan view of the center of the pedestal from underneath. Continuing with reference to these views, the adjustable leg  134  pivots on pin  138  located in the side flanges  140 ,  142  of the base. A link  144  connects between the adjustable leg  134  and a bell crank  146  by pivots  148  and  150 . A bell-crank  146  is attached to the pedestal base by pivot bolt  152 . A locking rod  154  is attached to the bell-crank  146  by pin  156  and passes through aperture piece  150 , which is secured to the trigger leg. The trigger leg  136  pivots on pin  158  located in the base side flanges. The adjustable leg  134  is free to move when the axis  160  of the aperture  158 , located on the trigger leg  136 , is aligned with the axis of the locking rod  154 . Binding between the trigger leg aperture  158  and the locking rod  154  locks the adjustable leg  134 . This is designed to lock when the trigger leg  136  is at the same angle as the fixed legs relative to the pedestal stem.  
       Telescopic Legged Table  
       [0099]    The preferred mechanism for a four-legged table, as depicted in FIG. 45, utilizes a binding arm  162  which is actuated by a slotted bar  164  as illustrated in FIGS. 43 and 44. The adjustable foot  66  and the trigger foot  168  both move longitudinally relative to their respective legs  170  and  172 . The locking rod  174  is attached to, or part of, the adjustable foot  166  and is concealed within the leg  170 . A trigger foot rod  176  is attached to, or is a part of, the trigger foot  168  and concealed within leg  172 . The binding arm  162 , attached to the frame by pivot  178 , contains an aperture  180  for the locking rod  174  to pass through. A pin  180  engages the binding arm with the actuation bar  164  via slot  182 . Another pin  184  engages a lever  186  with the actuation bar  164  via slot  188 . The lever  186  is attached to the frame by pivot  188  and connects with the trigger foot rod  175 . The actuation bar  164  is located in the frame by pivot  78  and pivot  188  passing through the horizontal slots. Movement of the trigger leg rotates lever  186  and in turn causes linear motion of the actuation bar  164 . This linear motion of the actuation bar  164  is transformed back to rotational motion of the binding arm  162 . The rotation of the binding arm  162  is limited by the two binding positions of the locking rod  174  in the aperture, locking on extension and locking on retraction.  
         [0100]    Alternatively, the binding arm  162  and the lever  186  could both contain crank arms connected with a linkage rod as utilized in the telescopic folding table example listed below.  
       Telescopic Folding Table  
       [0101]    The preferred mechanism for a telescopic folding table, as depicted in FIG. 46, is illustrated in FIG. 47. The adjustable leg  190  and the trigger leg  192  move longitudinally relative to the structure&#39;s legs. The locking rod  194  is attached at the bottom of the adjustable leg  190 , and the trigger rod  196  is similarly attached to the trigger leg  192 . The binding arm  198  is attached to the frame by pivot  200 , and lever  202  is attached to the frame by pivot  204 . The binding arm and the lever are connected by linkage rod  206 .  
       Builder&#39;s Trestle  
       [0102]    The preferred mechanism for a builder&#39;s trestle is a telescopic system with an external mechanism as detailed in FIG. 48, which is an elevation view of the lower portion of the trestle showing the self-locking system in detail for one set of the trestle&#39;s telescopic legs. In this arrangement the adjustable leg  200 , shown at near full extension, also acts as the locking rod. The adjustable leg  208  is a stepped tube, the larger upper section being free to slide inside the tube  210  of the trestle frame, and the smaller lower section  218  being free to slide through an aperture of the binding arm  214  when their axes are aligned. The larger upper diameter  209  serves to limit the extension of the adjustable leg  208 . The binding arm  214  is mounted to the trestle frame by pivot  220  and is connected to lever  222  by linkage rod  224 . Lever  222  is mounted to the trestle frame by pivot  224  and engages with the trigger leg  225  by having the end of the lever  222  located through a hole in the side of the trigger leg  225 . The trigger-leg  225  is free to slide inside the tube  227  of the trestle frame. When the trestle is placed, the adjustable leg  208  retracts until the trigger leg  225  also makes contact with the surface. A small retraction of the trigger leg  225  causes the binding arm  214  to slightly rotate and initiate friction binding of the adjustable leg  218 . When the trestle is lifted above a surface, a small extension of the trigger leg  225  moves the locking mechanism to the binding on extension position thus producing a friction locking in the other direction for the adjustable leg  208  and preventing it from dropping down.  
         [0103]    The system may be applied to one or two sets of the trestle&#39;s legs. Application to one set of legs provides stabilization only, while application, to two sets of legs allows the level of the trestle to be adjusted relative to the surface it is placed upon. In both applications, the locking of the adjustable leg is automatic. FIG. 49 is a sketch of a trestle showing the position of two sets of self-locking systems. The lower ends of all four legs are telescopic. Leg  230  triggers the locking of adjustable leg  232 , while leg  234  triggers the locking of adjustable leg  236 .  
       Parallel Feet Pivots with Trigger Foot Aperture  
       [0104]    This version of the self-stabilizing system has the locking aperture and trigger foot combined, and the adjustable foot pivot is parallel with the trigger foot pivot. It has a wide range of applications, but for ease of description, the ‘inverted-T-style’ table base, FIGS. 50 and 51, is utilized to illustrate the mechanism arrangement. The adjustable foot  238  is attached to the structure by pivot  240 . The locking rod  242 , connected to the adjustable foot by pivot  244 , passes through the locking aperture  246  in the trigger foot  248 . The trigger foot  248  is attached to the structure by pivot  250 . Gravity or springs  252  and  254  may be utilized to bias both the adjustable foot  238  and the trigger foot  248  to extend when free to do so. Free from a surface, the trigger foot  248  extends until the locking mechanism is in the binding on extension position. When being placed upon a surface, the trigger foot  248  retracts until the locking mechanism moves to the binding on retraction position. Between these two locking positions, the locking rod  242  is free to pass through the aperture  246 , permitting the adjustable foot  238  to extend if necessary. The adjustable foot can extend much further than the trigger foot, the latter&#39;s rotation being limited to a relatively small amount by the clearance between the locking rod and the aperture.  
         [0105]    The same mechanism layout, but placed in a different structure, may be applied for stabilizing various structure or appliances such as washing machines and refrigerators.  
       Trigger Foot Aperture with Feet Pivots at 90 Degrees  
       [0106]    The preferred mechanism for a pedestal base with trigger foot aperture is detailed with reference to FIGS.  52  to  54 . This arrangement utilizes the configuration of trigger foot and adjustable foot as depicted in FIG. 56. FIG. 52 is a sectional view showing the pedestal center and adjustable foot housing. FIG. 53 is a plan view of the underneath side of the pedestal base. FIG. 54 is a sectional view of the trigger foot housing. The adjustable foot  256  pivots on pin  260 , which is located in the pedestal base on a mounting block  262 . A linkage rod  264  connects the adjustable foot  250  with a bell-crank  266  located near the center of the pedestal base by pivot bolt  268 . Locking rod  270  is connected to the bell-crank  266  and passes through locking aperture  272 , which is part of trigger foot  274 . The trigger-foot  274  is mounted to the structure by bracket  276 , which has pivot pin  278  welded to it. Two springs, one ( 280 ) above the adjustable foot and one ( 282 ) above the trigger foot  274 , bias the feet to extend when free to do so. The fixed feet have not been shown in any of these figures. FIGS. 56 through 59 are alternative ways in which the trigger foot  274  and adjustable foot  256  can be arranged.  
       Pivoting/Telescopic Arrangement  
       [0107]    The preferred mechanism for white goods appliances, such as washing machines, dryers and refrigerators, is detailed in FIG. 60.  
         [0108]    [0108]FIG. 60 is a pictorial view with a cut-away showing the location of the pivoting/telescopic mechanism. The actual structural piece that the mechanism attaches to has not been drawn.  
         [0109]    This arrangement utilizes a pivoting trigger foot, a binding arm aperture, and a telescopic adjustable leg. The adjustable leg  300 , which doubles as the locking rod, passes through the locking aperture in the binding arm  302  and also through the locking rod guide  304  that is fixed to the structure. The binding arm is located by pivot  306  that attaches to the structure. Pivots  308 ,  310  connect a linkage bar  312  between the binding arm and the trigger foot  314 . The trigger foot  314  is located by pivot  316  that attaches to the structure. A spring  318 , located on the locking rod, biases the system to binding an extension of the adjustable foot when non-engaged with a surface. Contact of the trigger foot  310  with a surface moves the binding arm against the spring force to cause binding on retraction of the adjustable leg  300 . When the binding arm  302  moves through between the two binding positions, the adjustable leg  300  is free to either extend under gravity or retract as it contacts the floor.  
         [0110]    The mechanism would be placed at the rear of the appliance and conventional glides could be placed at the two front corners to provide the means for manual leveling. To operate the stabilizing mechanism, the appliance would be tilted onto the front glides to allow the stabilizing mechanism to release itself, and then back causing the adjustable foot to retract until the trigger foot makes contact and initiates the locking action.  
       Pivoting/Telescopic Arrangement  
       [0111]    The preferred mechanism for white goods appliances, such as washing machines, dryers and refrigerators, is detailed in FIG. 60.  
         [0112]    [0112]FIG. 60 is a pictorial view with a cut-away showing the location of the pivoting/telescopic mechanism. The actual structural piece that the mechanism attaches to has not been drawn.  
         [0113]    This arrangement utilizes a pivoting trigger foot, a binding arm aperture, and a telescopic adjustable leg. The adjustable leg  300 , which doubles as the locking rod, passes through the locking aperture in the binding arm  302  and also through the locking rod guide  304  that is fixed to the structure. The binding arm is located by pivot  306  that attaches to the structure. Pivots  308 ,  310  connect a linkage bar  312  between the binding arm and the trigger foot  314 . The trigger foot  314  is located by pivot  316  that attaches to the structure. A spring  318 , located on the locking rod, biases the system to binding an extension of the adjustable foot when non-engaged with a surface. Contact of the trigger foot  310  with a surface moves the binding arm against the spring force to cause binding on retraction of the adjustable leg  300 . When the binding arm  302  moves through between the two binding positions, the adjustable leg  300  is free to either extend under gravity or retract as it contacts the floor.  
         [0114]    The mechanism would be placed at the rear of the appliance and conventional glides could be placed at the two front corners to provide the means for manual leveling. To operate the stabilizing mechanism, the appliance would be tilted onto the front glides to allow the stabilizing mechanism to release itself, and then back causing the adjustable foot to retract until the trigger foot makes contact and initiates the locking action.  
       Scope of Invention  
       [0115]    The scope of this invention applies generally to all types of embodiments that could be devised and operable as or within any four-footed structure employing the self-stabilizing system, including but not limited to:  
         [0116]    tables and benches;  
         [0117]    washing machines and dryers;  
         [0118]    refrigerators and freezers;  
         [0119]    trestles and scaffolding;  
         [0120]    filing cabinets and floor cabinets;  
         [0121]    ladders and any indoor or outdoor apparatus.  
       Summary  
       [0122]    This invention provides an alternative and an improvement to known systems and methods for self-stabilizing tables, trestles, and other four-footed structures. The invention exists as a stabilizing assembly and, when placed on any surface, even or uneven, is self-adjusting and self-stabilizing. It can be built into a plurality of supports, meaning two out of four legs/feet in a typical table, or most four-legged structures. In a four-footed structure, it has two fixed feet, an adjustable foot, and a trigger foot. Its uniqueness is a result of the principle of its action, consisting of an adjustable foot, a means of locking the adjustable foot, and a trigger foot that initiates the locking action upon the adjustable foot.  
         [0123]    The locking action, in general, occurs when the axis of the locking rod and the axis of the aperture arm become non-parallel to each other, creating a friction-binding action.  
         [0124]    In operation, the four-footed structure settles onto the two fixed feet first and then the adjustable foot will extend or retract beyond the height of the fixed feet, and the trigger foot, in contacting the surface, will retract the small amount needed to initiate the locking of the adjustable foot. The mechanism is designed such that the final retraction of the trigger foot equals that of the adjustable foot after locking has been initiated and both fixed feet are already in contact with the surface. The trigger foot always retracts to the same height as the fixed feet. A benefit of this self-stabilizing system is that, once the feet are locked into position, it effectively behaves the same as a rigid four-footed structure.  
         [0125]    In addition, or summarize in greater detail, the ratio of leverage on the locking mechanism by the adjustable foot in relation to that of the trigger foot is designed such that the final retraction of the adjustable foot equals that of the trigger foot, beginning when the locking action commences and the structure (table) is being secured in place, with the two fixed feet already firmly in contact with the surface. This is further clarified in the description section of this document.  
         [0126]    In the claims, the “adjustable foot” is referred to as the “third support foot.” The “trigger foot” is referred to as the “fourth support foot.” 
         [0127]    The illustrated embodiments are only examples of the present invention and, therefore, are non-limitive. It is to be understood that any changes in the particular structure, materials and features of the invention may be made without departing from the spirit and scope of the invention. Therefore, it is my intention that my patent rights not be limited by the particular embodiments illustrated and described herein, but rather are to be determined by the following claims, interpreted according to accepted doctrines of patent claim interpretation, including use of the doctrine of equivalents and reversal of parts.
A structure has a first support foot, a second support foot, a third support foot and a fourth support foot. The four support feet are spaced apart. Preferably, the first support foot and the second support foot are fixed feet. The third support foot is vertically adjustable in position and the fourth support foot is vertically adjustable in position. A linkage means is interconnected between the third support foot and the fourth support foot. The linkage means includes lock means associated with the fourth support foot. The third support foot and the fourth support foot are vertically adjustable in position to place them substantially on a support surface together with the first support foot and the second support foot. The linkage means moves the lock means into a locked position in response to the third support foot assuming a predetermined vertical position on the support surface. When locked, the lock means functions to hold the third support foot and the fourth support foot in locked positions substantially on the support surface, so tha thte first the support foot, the second support foot, the third support foot and the fourth support foot are all substantially in contact with the support surface.