Abstract:
A pedestal head that is sufficiently resilient to allow for alignment of the floor panels during installation of the floor panels and to allow individual access floor panels to maintain their originally-aligned position after having been subjected to a heavy load during use. The pedestal head includes a base and arms extending from and supported by the base for cantilevered movement relative thereto. The base has a first surface, disposed in a first plane, configured to support a first portion of a floor panel. The arm has a second surface configured to support a second portion of the floor panel. The second surface is disposed in a second plane generally parallel to the first plane in a first configuration of the pedestal head. The arm is deflectable by the weight of a panel mounted thereon to define a second configuration in which the second surface is nonparallel to the first plane. The base may include additional arms for supporting additional floor panels. Each arm extends from and is supported by the base for cantilevered movement relative thereto. Each arm also has a surface disposed in the second plane for supporting another floor panel. Typically, four arms are provided to support the corners of four panels mounted on the arms in a substantially level, aligned position regardless of the differences in dimensions caused by variations in manufacturing tolerances.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention is directed generally to raised access floors having a plurality of individual floor panels supported by pedestals and, more particularly, to a resilient pedestal head for supporting the floor panels.  
         DESCRIPTION OF RELATED ART  
         [0002]    Raised access floors are widely used in commercial and industrial buildings where communication lines, air ducts, and other utilities are frequently altered or supplemented. These floors are a convenient way to hide utilities while offering easy access as needed. Raised access floors typically include a plurality of floor panels supported by a series of pedestals, which are typically arranged in a grid or matrix arrangement. The base of the pedestal attaches or rests on a subfloor. The floor panels are readily removable from the installed access floor and can be interchangeable with other floor panels. The pedestals can be adjustable to vary the finished floor height, and each pedestal usually includes a pedestal head. The floor panels are secured to or simply rest on the pedestal heads.  
           [0003]    It is important that raised access floors be level and the individual panels aligned. Unlevel access floors and misaligned panels can result in difficulties in moving equipment over the raised floor due to differences in height between adjacent panels or gaps between panels. Additionally, deflection of a floor panel subject to a heavy load may cause the floor to be uneven, further complicating the movement of equipment over or storage of equipment on the floor. Furthermore, misaligned panels can result in inefficiencies in under-floor heating, ventilation, and air conditioning (HVAC) systems, and, of course, are not aesthetically pleasing in appearance.  
           [0004]    By their very nature—being modular and individually removable—individual panels can become displaced out of the level plane of the floor, that is, panel edges can become misaligned creating gaps or variations across the floor. This can be a problem both during installation and use. As discussed above, floor panels can be secured to pedestal heads or can simply rest on the pedestal heads. Panels that can be secured typically include a hole in each corner that penetrates the entire floor panel. One type of conventional pedestal head includes a square, flat plate that generally includes four holes to receive fastening elements, such as bolts, to secure the corners of four floor panels to the pedestal head. Installing such floor systems requires manually aligning the holes in floor panels with holes in the flat plate pedestal head. However, when securing the floor panel to the conventional flat-plate pedestal head, differences in dimensions due to typical manufacturing tolerances often cause the bolts to be disposed in an oblique position with respect to an axis perpendicular to the subfloor. Because these conventional flat-plate pedestal heads are rigid, the differences in dimensions produced by manufacturing tolerances often results in gaps and misalignment of the edges of adjacent floor panels, which can produce an uneven floor surface. In general, installers utilize tools, such as hammers to apply external forces to attempt to bend, i.e., plastically deform, the pedestal head and/or the fastening elements until adjacent floor panels are level and aligned. However, the rigidity of the pedestal heads themselves hinders attempts to align misaligned floor panels.  
           [0005]    Another conventional pedestal head—the dual-level pedestal head—attempts to address the problem of imprecisions inherent in aligning floor panels that are secured to flat-plate pedestal heads. The conventional dual-level pedestal head generally includes an elevated bracket attached to the top surface of a square flat plate, thus dividing the square plate into four separate quadrants. This design permits an installer to slide or place the corners of the floor panels against the elevated bracket, which is an attempt to minimize the amount of manual alignment required by the installer. A further refinement to this conventional design includes raised elements on the lower, or flat-plate, portion of the dual-level pedestal head adapted to engage a corresponding recess or mating surface on the lower surface of the floor panels. Such refinements are often described as positive positioning or locking devices. While these types of features may help reduce the imprecisions inherent in manually aligning holes in the floor panels with holes in the pedestal head, such conventional pedestal heads still do not overcome all of the problems of misaligned floor panels due to imprecisions in manufacturing the floor panels and the holes therein, and the like. Moreover, it is believed that the elevated brackets attached to the top surface of the flat plate in the dual-level pedestal head design increase the rigidity of an already rigid flat plate. Thus, it is believed that this additional rigidity further compounds misalignment caused by manufacturing imprecisions as well as frustrates attempts by installers to manually manipulate the floor panels into alignment by deforming the pedestal head and/or the fastening elements.  
           [0006]    A related problem with conventional, rigid pedestal heads of both flat and dual-level designs is their propensity to plastically deform under certain loading conditions, which give rise to misalignment of the attached panels during use. Conventional pedestal heads generally support a small portion—typically the corners of the floor panels—of the lower surface of the floor panels. Loads that are applied to the corner of the floor panels act in direction substantially along the axial length of the pedestal, and are thus, resisted by the pedestal itself. However, loads that are applied away from the corners of the floor panels, e.g., near the middle of the floor panel, create large moments about the pedestal. These loads are resisted by the ability of the pedestal head to resist moments. It is believed that heavy loads applied away from the pedestal can cause the pedestal head to deform permanently. Thus, even conventional access floors that have been properly aligned when installed, may become misaligned following application of a heavy load to the floor panels. Because conventional pedestal heads are rigid and permanently deform under such loads, the pedestal heads and attached floor do not realign if the load is removed.  
           [0007]    Floor panels that have carpeting or laminate applied to their outer surface lack a hole in each corner. Instead of being secured to the pedestal head, such floor panels merely rest on the pedestal head. These floor panels usually do not experience the misalignment during installation as do floor panels that are secured to the pedestal heads. During use, however, unsecured floor panels can be susceptible to misalignment, just as the secured floors described above. But as unsecured floor panels are less rigid than secured floor panels, unsecured floor panels can become misaligned at loads lower than those required to deform and misalign secured floor panels.  
           [0008]    The foregoing demonstrates that known raised access floors suffer from a number of disadvantages including pedestal heads that do not compensate for manufacturing tolerances of floor panels and/or permanently deform after a load is applied to the floor panel, such that there is a resulting mismatch of the edges and/or top surfaces of adjacent floor panels.  
         SUMMARY OF THE INVENTION  
         [0009]    The invention solves the problems and avoids the disadvantages of the prior art by providing a pedestal head that is sufficiently resilient to allow for alignment of the floor panels during installation of the floor panels and to allow individual access floor panels to maintain their originally-aligned position after having been subjected to a heavy load during use. In particular, the invention accomplishes this by providing a resilient pedestal head for use in supporting floor panels of an elevated flooring system. The resilient pedestal head includes a base and an arm extending from and supported by the base for cantilevered movement relative thereto. The base has a first surface, disposed in a first plane, configured to support a first portion of a corner of a floor panel. The arm has a second surface configured to support a second portion of the corner of the floor panel. The second surface is disposed in a second plane generally parallel to the first plane in a first configuration of the pedestal head. The arm is deflectable by the weight of a panel mounted thereon to define a second configuration in which the second surface is nonparallel to the first plane. The base may also include additional arms for supporting additional floor panels. Each arm extends from and is supported by the base for cantilevered movement relative thereto. Each arm also has a surface disposed in the second plane for supporting another floor panel. In a preferred embodiment, four arms are provided, two on each side of the base, to support the corners of four panels. The arms on each side of the base may define, with the base, a generally u-shaped cross-section for supporting the panels mounted on the rear in a substantially level, aligned position regardless of the differences in dimensions caused by variations in manufacturing tolerances. Each arm may have an L-shaped cross sectional shape defined as a downwardly extending projection and a flange, generally perpendicular thereto. The distance between adjacent projections of the arms on each side of the base may vary to bias the arms into a position capable of providing restoring moments tending to offset deflections of the panels mounted on the arms due to manufacturing tolerances.  
           [0010]    According to another aspect of the invention, an elevated floor system is provided for supporting access floor panels, which includes first and second panels each having a corner and a pedestal having a head for supporting first and second panels. The pedestal includes a base having a first mounting surface supporting first portions of the corners of the first and second floor panels. The base also has first and second cantilevers extending therefrom. Each cantilever has a second mounting surface vertically spaced from the first surface and supporting a second portion of the corner of one of the first and second floor panels. The first and second mounting surfaces are disposed in substantially parallel planes prior to mounting the panels thereon. The first and second cantilevers are deflectable relative to the base under the weight of the first and second panels mounted thereon to define a second configuration in which the first and second surfaces are nonparallel. The second mounting surface of each cantilever may include a first hole and the first and second floor panels each may include a second hole. The first and second holes may be aligned to receive a fastener when one of the floor panels is mounted to one of the arms such that connection of the panels to the arms by fasteners force the arms to deflect into the second configuration due to dimensional variations between the panels and the head caused by manufacturing tolerances.  
           [0011]    In yet another aspect of the invention, a method of installing an elevated floor system composed of floor panels supported on a subfloor by pedestals having a pedestal head for supporting upper and lower portions of each floor panel on first and second vertically spaced mounting surfaces of the pedestal head is provided. The method includes the steps of a) disposing the upper portion of a first panel on the first mounting surface of a pedestal head and the lower portion of the first panel on a portion of the second mounting surface of the pedestal head; b) connecting the first floor panel to the second mounting surface of the pedestal head; c) disposing the upper portion of a second panel on the first mounting surface of the pedestal head and the lower portion of the second panel on another portion of the second surface of the pedestal head; and d) connecting the second floor panel to the second mounting surface of the pedestal head such that the panels create moments deforming the pedestal head to a position in which the first and second panels are non-parallel to each other. In addition the pedestal head may be plastically deformed to align the first and second panels in a level plane by applying a force in a region of the connected floor panels proximate the pedestal head, or applying a force to at least one of the first and second panels at a location spaced from the pedestal head. The connecting steps may include the steps of aligning a hole in the first floor panel with a first hole in the second surface of the pedestal head, and aligning a hole in the second floor panel with a second hole in the second surface of the pedestal head.  
           [0012]    Additional features, advantages, and embodiments of the invention may be set forth or apparent from consideration of the following detailed description, drawings, and claims. It is to be understood that the foregoing summary of the invention and the following detailed description are exemplary and intended to provide further explanation without limiting the scope of the invention as claimed. 
       
    
    
     BRIEF DESCRIPTIONS OF THE DRAWINGS  
       [0013]    The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate preferred embodiments of the invention, and, together with the detailed description below, serve to explain the principles of the invention.  
         [0014]    In the Drawings:  
         [0015]    [0015]FIG. 1 is a perspective view of a raised access floor structure with one panel removed to partially expose several resilient pedestal heads constructed according to the principles of the invention.  
         [0016]    [0016]FIG. 2 is a perspective view of a pedestal that may be used to support the resilient pedestal head of the invention.  
         [0017]    [0017]FIG. 3 is an enlarged perspective view of one of the resilient pedestal heads of the invention shown in FIG. 1.  
         [0018]    [0018]FIGS. 4A and 4B are plan and partial cross sectional views, respectively, of the pedestal head shown in FIG. 3, with FIG. 4B being taken along lines B-B of FIG. 4A. FIG. 5 is a plan view of a template for forming the pedestal head shown in FIG. 3.  
         [0019]    [0019]FIG. 6 is a partial perspective view of a floor panel that may be used with the pedestal of the invention.  
         [0020]    [0020]FIG. 7 is a perspective view of a pedestal, pedestal head and partially-installed access floor constructed according to the invention.  
         [0021]    FIGS.  8 A- 8 C are cross sectional views of the resilient pedestal head of the invention with attached floor panels showing three different positions the assembly may take based upon variations in dimensions produced during manufacture.  
         [0022]    [0022]FIG. 9 is a perspective view of second embodiment of a resilient pedestal head constructed according to the principles of the invention.  
         [0023]    [0023]FIGS. 10A and 10B are plan and partial cross sectional views, respectively, of the pedestal head shown in FIG. 9, with FIG. 10B being taken along lines B-B of FIG. 10A.  
         [0024]    [0024]FIG. 11 is a plan view of a template for forming the pedestal head shown in FIG. 9. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]    Reference will now be made in detail to preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. FIG. 1 shows a perspective view of part of a raised access floor system  10  constructed in accordance with a preferred embodiment of the invention. As shown in FIG. 1, the raised access floor system  10  is installed on a subfloor  20  and generally includes floor supports such as pedestals  30  having resilient pedestal heads  40  used to support floor panels  50 .  
         [0026]    Typically the pedestals  30  are arranged in a grid-like pattern with pedestals  30  spaced substantially equidistant from one another. The height of pedestals  30  may be adjustable as is known in the art. The pedestals  30  support the corners of the floor panels  50 , thus forming the raised floor system  10 . Each one of the pedestals  30  that is located in middle portions of the raised floor system  10  supports corners of four of the floor panels  50 . Each one of the pedestals  30  that is located along edge portions of the raised floor system  10  supports corners of two of the floor panels  50 , while each one of the pedestals  30  located at an end portion of the raised floor system  10  supports a corner of one of the floor panels  50 . The panels  50  may rest on or be attached to pedestal heads  40 , and each one of the floor panels  50  is individually removable to provide access to the subfloor  20  located beneath the raised flooring.  
         [0027]    Pedestal  30  is preferably an adjustable pedestal of the type, for example, shown in FIG. 2. However, any conventional type of pedestal may be used in accordance with the principles of the invention. The pedestal  30  in FIG. 2 generally includes a base  32 , a post  34 , a rod  36 , and an adjusting device  38 . The base  32  is shown as being generally square-shaped but can be a variety of other geometric shapes, including circular or rectangular, and the corners of the base  32  may be rounded as shown in FIG. 2. The base  32  may be a substantially flat plate. Alternatively, the base  32  can include raised or web-like portions, which are believed to impart greater structural strength and rigidity than a substantially flat plate. The base  32  can rest on or be secured to the subfloor  20 , as is known in the art. If the base  32  is to be secured to the subfloor  20 , a plurality of anchor holes  33  may be disposed in the base  32 . The anchor holes  33  may be adapted to accept conventional anchor devices, including concrete expansion anchors. Alternatively, the base  32  may be secured to the subfloor  20  by an adhesive or any other method or means known in the art.  
         [0028]    The post  34  is coupled rigidly to the base  32  and extends substantially perpendicularly therefrom. The post  34  has a lower end  34   a  attached to the base  32  and an upper end  34   b  adapted to receive the rod  36 . The cross-section of the post  34  can be a variety of geometric shapes, including circular, rectangular, or square, but as shown in the figures, the cross-section of the post is square. The corners of post  34  may be square, beveled or rounded. The post  34  and the base  32  may be formed separately or as a unitary whole. If the post  34  and the base  32  are formed separately, the lower end  34   a  of the post  34  may be fixedly connected to the base  32  by at least one weld  35 . Alternatively, the lower end  34   a  of the post  34  may be connected to the base  32  by providing the base  32  with a raised threaded portion (not shown) and the lower end  34   a  of the post  34  with a complementary surface (not shown) adapted to engage the threaded portion of the base  32 . Again, any other means known in the art for making or connecting the base and post together to form the pedestal may be employed.  
         [0029]    If an adjustable height pedestal is employed, the rod  36  may be coupled to the upper end  34   b  of the post  34  in any number of ways known in the art to provide a lockable, variable height between subfloor  20  and floor panels  50 . For example, in the illustrated embodiment, the rod  36  is slidably received within the upper end  34   b  of the post  34 . The outer surface of the rod  36  may be threaded along the entire axial length or a sufficient portion of the axial length of the rod  36  to engage the inner surface of an adjusting device  38 , such as nut  38  described below, which sits on top of post  34  and receives the lower end of the rod  36 . By virtue of the engagement between the rod  36  and nut  38 , rod  36  telescopes within the post. Thus, the height of the pedestal  30  can be adjusted by rotating nut  38 , which varies the position of the rod  36  with respect to the post  34 . Once a desired height of the pedestal  30  is obtained, the position of the rod  36  with respect to the post  34  is fixedly secured in a predetermined position by a locking projection that extends from the threaded surface on the end of the rod  36  and prevents rod  36  from rotating within post  34 .  
         [0030]    As shown in FIG. 2, nut  38  may include one or more axial projections  38   a . The axial projections  38   a  extend from the top and bottom opposing faces of nut  38  (only the top face is shown in FIG. 2). Two axial projections  38   a  are provided to allow either end of the adjusting device  38  to be threaded onto the rod  36 , but only one is required to prevent rotation of nut  38 . Nut  38  may be threaded onto bottom end of rod  36  if the top end is already connected to the pedestal head  40  (as shown in FIG. 3) into a desired position along the length of the threads. If rod  36  and pedestal head  40  are not yet connected, nut  38  may be threaded onto top end of rod  36 . When the nut  38  is seated on the top surface of the upper end  34   b  of the post  34 , the bottom projection  38   a  of nut  38  prevents rotation of the nut relative to post  34 . Furthermore, the weight of the installed floor panels  50  upon the pedestal head supported by the post  36  (FIG. 3) provides additional compressive loads that act to fully seat the nut on the post  34 , thus preventing rotation of nut  38  in use.  
         [0031]    Any other adjustable or non-adjustable pedestal known in the art may be used with the resilient pedestal head of the invention. For example, the adjusting device  38  can be a seating-lock type, a spring stop-nut type, a prevailing torque type, a wedge type, or a quick-release type. In addition, the inner surface of post  34  may be threaded to engage directly the threads on rod  36  and a conventional set screw threadably received in a side of post  34  may be used to lock the in position with respect to post  34 .  
         [0032]    Referring to FIGS. 3, 4A, and  4 B, a resilient pedestal head  40  made in accordance with the principles of the invention is shown. As shown in FIG. 3, the pedestal head  40  is fixedly connected to the rod  36  of the pedestal  30  by any means known in the art, such as welding or by providing the pedestal head  40  with a complementary surface (not shown) adapted to engage the threaded surface of the rod  36 . Thus, as described above, the position or height of the pedestal head  40  relative to the subfloor  20  changes when the height of rod  36  is adjusted within post  34  by nut  38 . Pedestal head  40  generally includes a top plate  42  having four L-shaped arms formed by downwardly depending projections  46  and flanges  44  outwardly extending therefrom in a cantilevered fashion for supporting floor panels  50 . As the top plate  42  also is adapted to support one or more floor panels  50  in a manner discussed herein, the top (uppermost) surface of the top plate  42  will typically be substantially flat as illustrated. Thus, the top surface of the top plate  42  lies in a plane substantially horizontal and substantially transverse to vertical axis A shown in FIG. 4B. Extending outwardly from the center of the top plate  42  are four extensions  42   a , each of which preferably have substantially the same length and such that the top surface of plate  42  has a generally cross-shape. The extensions  42   a  form corner regions  42   b  on the top surface to receive a corner of a panel  50 . Only two of the four extensions  42   a  include the projections  46  and panel supporting flanges  44 . The other two of the extensions  42   a  include downwardly depending skirts  42   c  to strengthen top plate  42 . The top plate  42  may include a number of holes  42   d  formed in extensions  42   a  for manipulating and aligning the pedestal head  40  during manufacture, e.g. during the stamping and forming process described below. The projections  46  depend downwardly from two opposed extensions  42   a  such that the flanges  44  of each L-shaped arm are spaced from and substantially parallel to the surface of the top plate  42 . Flanges  44  may have substantially the same length and are adapted to support a corner portion of the floor panels  50 , as described in more detail herein. As shown, the lengths of the flanges  44  may be similar to the lengths of the extensions  42   a . Each of the flanges  44  may include at least one alignment hole  45 , which may be threaded and include an upstanding projection  45   a . The alignment hole  45  is adapted to receive a fastening element  60 , which is shown in FIG. 6. When the alignment hole  45  fully receives the fastening element  60 , the floor panel  50  is attached to the pedestal head  40 . As shown best in FIG. 4B, the projection  45   a  protrudes above the top surface of the flanges  44  and is received in a complementary countersunk hole (not shown) in the lower surface  56  of floor panels  50  to facilitate alignment and connection of the floor panels  50  to the pedestal head  40 . The outer walls of the projection  45   a  may be angled with respect to a centerline C of the alignment hole  45  as shown in FIG. 4B to form a complementary engaging surface with the countersunk hole (not shown). Alternatively the outer walls of the engaging projection  45   a  could be parallel to the centerline C of the alignment hole  45 .  
         [0033]    Referring to FIG. 4A, distances C 1 , C 2 , C 3 , and C 4  each represent the distance between the centerline of an alignment hole  45  and the center of one of the extensions  42   a  of the plate  42 . Preferably, the distances C 1 , C 2 , C 3 , and C 4  are substantially the same. As shown, C 34  represents the total distance between the centerlines of the alignment hole  45  in the flanges  44  extending from projection  46  on the same extension  42   a.    
         [0034]    The L-shaped arms  46 ,  44  of each extension  42   a  may be symmetrically disposed in pairs about the axis A as shown in the side view of FIG. 4B. Extension  42   a  and L-shaped arms  46 ,  44  on each side of plate  42  have an inverted, generally U-shape cross-section as shown best in FIGS. 3 and 4B. The distance D 1  represents the distance between the inner walls of a pair of projections  46  at the bottom of the top plate  42 , while the distance D 2  represents the distance between the inner walls of the pair of projections  46  at the junction between the projections and flanges  44 . Because the L-shaped arms  46 ,  44  are designed to deform under panel loading as described below, and in certain conditions may deform inwardly towards each other, the distance D 2  may be greater than the distance D 1 . In the preferred embodiments of the invention, D 2  is greater than D 1  by approximately five one hundredths of an inch, but this dimension will obviously vary depending upon the particular floor and application being designed. Each L-shaped arm  46 , 44  is supported solely by a portion of a respective extension  42   a , thus forming a cantilever, which is deformable by loads typically encountered during installation of the raised access floor system  10 , described in more detail in FIGS.  8 A- 8 C.  
         [0035]    The top plate  42 , extensions  42   a , projections  46 , and flanges  44  of pedestal head  40  can be formed integrally by any number of conventional forming techniques, such as stamping, casting, or the like. As shown in FIG. 5, the pedestal head  40  may be stamped from a single piece of material. FIG. 5 illustrates a template for stamping the plate  42  of the invention. The dashed lines on the template illustrated in FIG. 5 indicate where the stamped template is to be shaped to form the pedestal head  40  of the invention. Alternatively, the pedestal head may be constructed from any number of separately formed pieces that are subsequently attached together. The material of the pedestal head  40  can include a variety of metals or composites as long as they have sufficient strength, durability, and resiliency to support access floor panels according to the principles of the invention. Currently, the preferred material for the pedestal head  40  is half-hard, high density hot-dipped galvanized steel coil having a yield strength of at least 50,000 pounds per square inch. Preferably, the thickness of the plate is less than one-eighth of an inch, but may, of course vary depending upon the particular application. Pedestal head  40  can be used with conventional panels of the type, for example, described herein as floor panels  50 . Any type of panel known in the art may be used in accordance with the invention. Referring to FIG. 6, a section of a corner of one of the floor panels  50  is shown. Each of floor panels  50  has an upper surface  52 , an intermediate portion  54 , and a lower surface  56 . The upper surface  52  and the lower surface  56  are shown as substantially square in shape, but obviously can be formed in a variety of geometric shapes. Also, the floor panels  50  can be cut or formed to adapt the floor system  10  to a particular configuration. The upper surface  52  typically is substantially parallel to the lower surface  56 . The surface area of the upper surface  52  is shown as being greater than the surface area of the lower surface  56 , thus forming a lip or an overhang  52   a , which may be extended on the order of less than an inch from the side of intermediate portion  54 . The intermediate portion  54  extends between and connects the upper surface  52  and the lower surface  56 . The intermediate portion  54  may be hollow, may include a stiffening structure, or may be filled with various materials, including wood, metal, composites, or concrete or other materials to achieve different strength or aesthetic characteristics as known in the art. Thus, depending upon the application, different types of floor panels may be used. Although not shown, a floor panel lacking panel holes because laminate or carpeting will be applied to the upper surface of the floor panel may also be used.  
         [0036]    The floor panels  50  may be affixed to pedestal head  40  by fastening elements  60  such as bolts, screws, or pins, or may simply rest on the pedestal head  40 . In either case, the floor panels  50  are removable for access to an area below the floor panels  50 . In the preferred embodiments, several panel holes  58  are formed in the floor panels  50 . Each of the panel holes  58  is disposed in a corner region of the floor panels  50 . The panel holes  58  traverse the entire floor panel  50 , i.e., they extend through the upper surface  52 , the intermediate portion  54 , and the lower surface  56 . The panel  50  is generally aligned on the pedestal head  40  when disposed in a corner region  42   b  between two extensions  42   a . To more precisely align the hole  58  in the panel  50  with the alignment hole  45  in pedestal head  40 , the lower surface  56  of at least one corner of panel  50  has countersunk hole (not shown) adapted to receive the engaging projection  45   a  of the alignment hole  45 .  
         [0037]    The installation and use of the raised access floor system  10  of the invention will now be described. Referring to FIGS. 7 and 8A, after the pedestals  30  are placed upon the subfloor  20 , the desired number of floor panels  50  are placed upon the pedestal heads  40  such that the upper surface  52  of the floor panels  50  rests on the top plate  42  and the extensions  42   a  of the pedestal head  40 , and the lower surface  56  of the floor panel  50  rests on the flanges  44 . As described above, as a corner of floor panel  50  is manipulated onto the pedestal head  40 , receipt of the projection  45   a  of the alignment hole  45  into a complementary engaging surface of the lower surface  56  of the floor panel  50  aligns the hole  45  in the pedestal head  40  and the panel hole  58 . To secure a floor panel  50  to a pedestal head  40 , fastening elements  60  are inserted into panel holes  58  and alignment holes  45  and tightened to connect the panel  50  to pedestal head  40 . The method of securing floor panels  50  to pedestal head  40  is the same regardless of the number of floor panels  40  to be secured. For example, as shown in FIG. 8A, a first panel  50  is placed on a corner  42   b  of pedestal head  40  such that projection  45   a  on pedestal head  40  is received within the countersunk hole (not shown) in panel  50 . Then, fastening element  60  passes through panel hole  58  and is torqued down into alignment hole  45  to secure panel  50  to pedestal head  40 . The same is done with other panels  50 . The steps described herein can be performed in any order.  
         [0038]    Referring to FIGS.  8 A- 8 C, certain aspects of the installation of floor panels  50  onto pedestal head  40  now will be described to illustrate one of the benefits of the resilient pedestal head of the invention. FIGS.  8 A- 8 C illustrate two floor panels  50  secured to one of the pedestal heads  40  by two fastening elements  60  in three different configurations by virtue of dimensional variances caused by, e.g., manufacturing tolerances. FIG. 8A shows the level configuration that occurs when the panel holes  58  are perfectly aligned, while FIGS. 8B and 8C show angled configurations that can occur when the panel holes are not aligned but within tolerance. Referring to FIG. 8A, the distance between the centerlines of the panel holes  58  in two adjacent floor panels  50  is represented by C p , and the distance between centerlines of corresponding alignment holes  45  is represented by C 34  (see discussion of FIG. 4A above). In FIG. 8A, the distance C p  is substantially equal to the distance C 34  and the top surfaces of the panels  50  are aligned and in the same level plane. When distance C p  is greater than the distance C 34 , by even very small amounts, significant benefits can be achieved to overcome misalignment of floor panels  50  during installation caused by dimensional variations. For example, it has been found that when distance C p  is slightly greater than C 34 , for example by a difference on the order of 0.010 inches, sufficient pre-bias is produced in the L-shaped arm  46 , 44  of the pedestal head  40  to exert forces F 1  and F 2  and restoring moments M 1  and M 2  that tend to press the edges of adjacent floor panels  50  together after fastening elements  60  are attached to the pedestal head  40 . In a preferred embodiment of the invention, C p  may be 2.000 inches and the distance C 34  may be 1.990 inches. Under these conditions, as the panel holes  58  are aligned with holes  45  in FIG. 8A are perfectly aligned, when panels  50  are screwed in, the two floor panels  50  will be aligned with little or no manipulation required by the installer. Although prebiasing the head by designing C p  to be greater than C 34  is preferred and is a feature shown in FIGS. 8A and 8B, the invention may be practiced with C p  being equal to C 34 .  
         [0039]    [0039]FIGS. 8B and 8C illustrate the alignment feature produced by the resilient head of the invention when C p  is greater than C 34  by more than 0.010 inches or C p  is less than C 34 . In FIG. 8B, the distance C p  between the panel holes  58  of adjacent panels  50  is greater than the distance C 34  by more than 0.010 inches. It is believed that such a discrepancy between the distance C p  and the distance C 34  can result, for example, from tolerances in manufacturing the floor panels  50 . As the fastening elements  60  are torqued down, the increased distance of C p  causes the fastening element  60  to enter aligning hole  45  at an angle transverse to axis A. Because the cantilevered construction imparts flexibility in L-shaped arm  46 , 44 , the pedestal head  40  deforms such that distance D 2  becomes gradually less than distance D 1  as fastening element continues to be tightened. This deflection of the pedestal head  40  causes the interface between adjacent panels  50  to bow in an upward direction relative to the subfloor  20  as shown in FIG.  8 B. The amount of deflection illustrated in FIG. 8B is exaggerated for illustration purposes and typically may be on the order of hundredths of an inch. After the fastening elements  60  have been secured fully to the pedestal head  40 , a load can be applied by the installer to the bowed floor panels  50  in a region near the pedestal head  40  to permanently deform the pedestal head  40  to the level configuration illustrated in FIG. 8A. Preferably, the load is applied substantially along the axis A in a direction toward the subfloor  20 . Thus, in this manner, the floor panels  50  can then be aligned in a level, substantially horizontal position.  
         [0040]    [0040]FIG. 8C illustrates the condition when the distance C P  is less than the distance C 34 . As the fastening elements  60  are torqued down, the decreased distance of C p  causes the fastening element to enter aligning hole  45  at an angle transverse to axis A. Because the cantilevered construction imparts resiliency in L-shaped arm  46 , 44 , the pedestal head  40  deforms such that distance D 2  becomes greater than distance D 1  as fastening element  60  continues to be tightened. This deflection of the pedestal head  40  causes the interface between adjacent floor panels  50  to bow in a downward direction relative to the subfloor  20 . Again, the amount of deflection illustrated in FIG. 8C has been exaggerated for illustration purposes, but may be on the order of hundredths of an inch in practice. After the fastening elements  60  have been secured to the pedestal head  40 , a load can be applied to the bowed floor panels  50  by the installer to permanently deform the pedestal head  40  to the level configuration illustrated in FIG. 8A. Preferably, the load is applied in a direction toward the subfloor  20  on an end of the panel  50  away from the pedestal head  40 . Thus, in this manner, the floor panels  50  can then be aligned in a level, substantially horizontal position. Once the raised access floor system  10  has been completely installed and leveled, the system  10  is rigid by virtue of the strength of the individual pedestal heads  40  and by the overall constraint of the interconnected system  10 . The system  10  of interconnected floor panels  50  and pedestal heads  40  provide greater rigidity than is to be found in an individual pedestal head  40  alone.  
         [0041]    In accordance with the present invention, the floor panels  50  do not have to be secured to the pedestal heads  40 . For example, as described above, where carpet or laminate is applied to the upper surface  52  of the floor panels  50 , the panel holes  58  are covered, and thus, unable to accommodate the fastening elements  60 . The panels  50  simply rest upon the pedestal head  40 . As there are no fastening elements producing moments to deform the pedestal head  40 , the adjacent panels are aligned without the need for manipulation. Of course, there may be some minor misalignment resulting from the weight of floor panels  50  alone. However, such misalignment should be difficult to detect and can easily be corrected by minor physical manipulation by the installer. FIG. 8A also represents the installed configuration where the floor panels  50  simply rest on the pedestal heads  40 . FIG. 8B also is an exaggerated representation of the unsecured configuration when a heavy load is applied to the floor panels  50  away from the pedestal head. Again, the amount of actual deflection may be on the order of hundredths of an inch. After the load is removed from the pedestal heads  40 , the cantilevered construction of L-shaped arm  46 , 44  provides sufficient resiliency to pedestal head  40  that pedestal head  40  returns to the level configuration illustrated in FIG. 8A. Because in this configuration the panels are not secured to the head by fastening elements, the entire system  10  is less rigid than the system  10  in which the panels are secured. Thus, even though this unsecured configuration may deflect at lower loads, the resiliency of the individual panel head  40  is sufficient to return to the level configuration illustrated in FIG. 8A when the localized load is removed.  
         [0042]    Applicants have performed tests to demonstrate the resiliency and strength of the invention. Applicants attached a single Maxcess Technologies, Inc. RWC 400 floor panel to a pedestal head of the invention constructed according to the embodiment shown in FIG. 3. The RWC 400 floor panel is a commercially available panel marketed by the assignee of the invention that is a resistance-welded, concrete-filled steel panel designed for heavy-duty applications. In performing the test, point loads were applied to the attached floor panel six inches in from both sides of the corner mounted on the pedestal head. Strain gauges were placed near the point of application of the load on the panel and at the corner bolt hole on the pedestal head to measure the deflection of both the panel and the pedestal head. At a load of 800 pounds, the pedestal head deflected 0.020 inches and with no measurable permanent deflection. Thus, the head was elastically deformed under this loading. At this load, the panel deflected 0.040 inches. At a load of 1,350 pounds, the pedestal head deflected 0.035 inches and with a permanent deformation of 0.004 inches. At this load, the panel deflected 0.080 inches. The ultimate load of the pedestal head before failure was determined to be greater than 3,000 lbs. with a corresponding permanent deformation of 0.10 inches.  
         [0043]    [0043]FIGS. 9, 10A,  10 B, and  11  illustrate another embodiment of a pedestal head of the invention. Like numbers will be used to describe like elements. As shown in FIG. 9, the pedestal head  140  is fixedly connected to the rod  136  by any means known in the art, such as welding or by providing the pedestal head  140  with a complementary surface (not shown) adapted to engage the threaded surface of the rod  136 . As described above, the position or height of the pedestal head  140  relative to the subfloor  20  changes when the height of rod  136  is adjusted within post  134  by nut  38 . Pedestal head  140  generally includes a top plate  142  having four L-shaped arms formed by downwardly depending projections  146  and flanges  144  outwardly extending therefrom in a cantilevered fashion for supporting floor panels  50 . As the top plate  142  is adapted to support one or more floor panels  50  in a manner discussed herein, the top (uppermost) surface of the top plate  142  will typically be substantially flat as illustrated. Thus, the top surface of the top plate  142  lies in a plane substantially horizontal and substantially transverse to vertical axis A shown in FIG. 10B. Extending outwardly from the center of the top plate  142  are four extensions  142   a , each of which preferably have substantially the same length. The top surface of extensions  142   a  form four corners  142   b  on the top surface each of which receives a corner of a panel  50 . Top plate  142  includes skirt  142   c  to strengthen top plate  142 . Unlike the embodiment shown in FIG. 3, the L-shaped arms  146 , 144  in this embodiment depend from each extension  142   a , such that each extension has a strengthening skirt on one side and an arm  146 , 144  on the other. The top plate  142  may include a number of holes  142   d  formed in extensions  142   a  for manipulating and aligning the pedestal head  40  during manufacture of the pedestal head  140 , during the stamping and forming process described below. The projections  146  depend downwardly from one side of each extension  142   a  such that the flanges  144  are spaced from and substantially parallel to the surface of the top plate  142 . Flanges  144  each have substantially the same length and are adapted to support a corner portion of the floor panels  50 , as described in more detail herein. As shown, the lengths of the flanges  144  may be similar to the lengths of the extensions  142   a . Each of the flanges  144  may include at least one alignment hole  145 , which may be threaded and include an upstanding projection  145   a , and functions in the same manner as discussed above in connection with the first embodiment of pedestal head  40  to facilitate alignment and connection of the panels  50  to head  140 .  
         [0044]    Referring to FIG. 10A, distances C 1 , C 2 , C 3 , and C 4  each represent the distance between the centerline of an alignment hole  145  and the center of one of the extensions  142   a  of the plate  142 . Preferably, the distances C 1 , C 2 , C 3 , and C 4  are substantially the same. As shown, C 34  represents the total distance between the centerlines of the alignment hole  145  in the flanges  44  on one side of the plate.  
         [0045]    The projections  146  of each extension  142   a  may be parallel to the vertical axis A as shown in FIG. 10B. The top plate  142 , extensions  142   a , projections  146 , and flanges  144  of pedestal head  140  can be formed integrally by any number of conventional forming techniques, such as stamping, casting, or the like. As shown in FIG. 11, the pedestal head  140  preferably is stamped from a single piece of material. FIG. 11 illustrates a template for stamping the plate  142  of the invention. The dashed lines on the template illustrated in FIG. 11 indicate where the stamped template is to be shaped to form the pedestal head  140  of the invention. Like the first embodiment, the pedestal head may also be constructed from any number of separately formed pieces that are subsequently attached together, and the material of the pedestal head  40  can include a variety of metals or composites as long as they have sufficient strength, durability, and resiliency to support access floor panels according to the principles of the invention. The installation and use of the embodiment of the invention illustrated by FIGS. 9, 10A,  10 B, and  11  are substantially the same as that described above and in FIGS.  8 A- 8 C, and thus, will not be repeated here.  
         [0046]    Although the foregoing description is directed to the preferred embodiments of the invention, it is noted that other variations and modifications will be apparent to those skilled in the art, and may be made without departing from the spirit or scope of the invention.