You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
TECHNICAL FIELD 
     The present invention relates to floor systems of the type having removable floor panels supported by pedestals located in a subfloor plenum area. 
     BACKGROUND OF THE INVENTION 
     For versatility of construction and layout, and ease of access to utilities and ducts, it has been proposed to run ducts, wiring and plumbing in plenum beneath a floor structure having removable floor panels resting on pedestals in a modular layout. However, to make such an arrangement practical there must be provision for easily leveling the floor and for sealing the floor panels from the subfloor plenum area. 
     SUMMARY OF THE INVENTION 
     The present invention provides an improved floor leveling and sealing system incorporating removable floor panels resting on pedestals in which the pedestals comprise screw jacks operated from the top of the pedestals. The floor panels are recessed at their corners to provide space for removable hold-down caps which cover the top of the pedestals and give access for a tool to adjust the screw jacks. The caps are clamped down against shoulders on the adjacent floor panels by screws threaded into the pedestals, and the panels are in turn seated on support rings mounted on the pedestals. Downturned lips at the recessed corner portions of the floor panel interfit with the support rings. The mounting of the support rings on the pedestals is such that the turnable screw jack component of the pedestals can be turned for adjustment within the respective support ring. Extension and retraction of a pedestal by adjustment of its screw jack components, results in raising and lowering of the respective support ring, and hence causes raising and lowering of the floor panels resting on the support ring. 
     The floor panels and the caps each have a peripheral sealing gasket which is compressed when the adjoining panels and caps are in position. The gaskets are located above the level of the floor panel shoulders on which the caps are seated. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded view of a pedestal unit and showing related recessed corner portions of two adjoining floor panels; 
     FIG. 2 is a perspective plan view of a floor section formed by the present invention and showing one of the pedestals in elevation with the respective hold-down cap and screw in exploded relation; 
     FIG. 3 is a vertical sectional view taken as indicated by line 3--3 in FIG. 2, and showing the manner of applying a wrench for extension or retraction of the respective pedestal; and 
     FIG. 4 corresponds to FIG. 3 after adjustment and positioning of the respective hold-down cap. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In accordance with the present invention, rectangular floor panels 10 are supported at corner portions on vertically adjustable pedestal assemblies 12, each having a base 14, column 16, bearing washer 18, and panel support ring 220. The upper end of each column 16 has an internally threaded hex-head 22 for receiving a clamping screw 23 passing through a square hold-down cap 24. At its lower end, each pedestal base 14 has support feet 26 and interfits with a respective horizontal adjustment plate 28 permitting limited horizontal movement of the base 14 on the underlying subfloor 30. 
     The floor panels 10 are preferably of molded plastic construction providing a durable plastic skin 10a enclosing a structural foam core 10b. The corners of the floor panels are blunted and shaped to provide a recessed cap seat 32 spaced above an annular groove 34 surrounded by an annular restraining lip 36. 
     Each panel has a sealing gasket 38 therearound fitting into a peripheral groove 39 in the panel located above the level of the cap seats 32. Likewise, each hold-down cap 34 also has a surrounding sealing gasket 40 fitting into a peripheral groove 41. 
     The lower end portion of the column 16 is externally threaded and screws into the base 14 for vertical adjustment of the effective height of the pedestal and, more specifically, the height of an annular ledge 42 on the column. This ledge 42 serves as a seat for the bearing washer 18 on which the support ring 20 is in turn seated to support the corner portions of four of the panels 10. 
     The support ring 20 has a circular groove 20a surrounded by a circular support lip 20b to provide a torque and groove interfitting relationship with the restraining lip 36 and groove 34 at the adjoining corner portions of four floor panels 10. In this relationship, the upper wall of the panel groove 34 seats against the top of the support tip 20b of the support ring 20 and the panel restraining lip 36 depends into the groove 20a of the support ring. Preferably, the depending lip 36 is horizontally narrower than the groove 20a and has substantially the same mean radius as the groove 20a so that there is a reasonable horizontal adjustment tolerance between the floor panels and each support ring 20. Similarly, it is preferred that the center opening 20c in the support ring 20 be larger than the outside diameter of the column 16 to provide additional horizontal adjustment tolerance for the floor panels relative to the pedestals 12. 
     The seats 32 at the adjoining corner portions of four of the floor panels collectively provide a square seat for engagement by the bottom edge of a depending peripheral lip 34a of a respective one of the square hold-down caps 34. The caps 34 have a tapered center hole 34b for receiving the clamping screws 23 which are adapted to be threaded into the hex-heads 22 on the pedestals such as to be flush with the upper surface of the caps when they are in turn flush with the upper surface of the related floor panels. This normally occurs when the bottom lip 34a of each cap is seated on the seats 32 at the corner portions of the related panels. 
     The caps 34 are of a size to provide, when removed, an opening around the hex-head 22 of the related pedestal which is large enough to provide easy application of a socket wrench to the hex-head for turning the respective column 16 relative to the related base 14 and relative to the related support ring 20. In this manner, the height of the pedestals 10 can be readily adjusted for leveling the floor panels. 
     Providing the support ring component 20 of each pedestal assembly 10 as a separate part permits the pedestal heights to be adjusted without turning of the support rings relative to the floor panels. Although this arrangement is advantageous and is preferred, it will be appreciated that the support rings 20 could be integrated with the columns 16. 
     The pedestal bases 14 may be secured to the underlying subfloor. However, it is preferred to provide for limited horizontal movement of the pedestals relative to the subfloor. For this reason, the pedestal base 14 has a tapered bottom cavity 14a to fit over an open-ended frusto-conical alignment post 28a of smaller size provided by the adjustment plates 28. Each adjustment plate is adapted to be stapled or otherwise secured to the subfloor and has four equally spaced radially extending slots 28b which are tapered to expand in width toward their outer ends. These slots 28b accommodate the pedestal feet 26 such that each pedestal is free to skid on the subfloor a limited amount defined by the clearance of the alignment posts 28a within the base cavities 14a. The side edges of the slots 28b limit turning of the pedestal bases 14 relative to the subfloor. 
     In utilizing the present floor panel system, it is preferred to mark the surface of the subfloor with an x-y grid corresponding to the size of the floor panels. Then the adjustment plates 28 are positioned and secured in place with their posts centered over the grid&#39;s intersections. The pedestal assemblies 12 are then positioned over the plates 28 following which the floor panels 10 are seated in place on the support ring components 20 of the pedestals. During this process, the pedestals can move as may be necessary relative to the subfloor. The column components 16 are then screwed relative to the base components 14 and panels 10 to level the panels. Finally, the caps 24 are applied to the pedestals and clamped down by the screws 23 to in turn clamp the panels 10 down against the support rings 20. During this clamping operation, the peripheral gaskets 38, 40 on the floor panels 10 and caps 24 are pressed together and provide a total joint seal. The gaskets 38, 40 preferably comprise vinyl or butyl tubing. 
     The described floor system permits the individual floor panels 10 to be easily removed for ready access to the underlying plenum by initially removing the related caps 24 after loosening the respective screws 23. 
     It will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.

Summary:
A floor system has removable floor panels resting at their corners on support rings provided by vertically adjustable pedestal units. The upper ends of the pedestal units have hex-heads for receiving a height adjusting tool. Access to the hex-heads is obtained by removing cornercaps held in place by screws threaded into the hex-heads. The support rings do not turn while the pedestal units are being adjusted in height.