Abstract:
The retractable table has a single, centrally disposed, vertical lift column formed of a relatively large number of relatively short sections. The relatively short sections permit the table to retract into a relatively shallow receptacle, thus obviating need for a deep well to house the column when retracted. Column actuation may be achieved by various principles of operation, including hydraulic cylinders and helically threaded sections which are rotated to extend and retract the tabletop. The table has an anti-rotation feature to prevent rotation of the tabletop relative to the underlying receptacle in which it stores. The retractable table may be provided as a “drop-in” installation, with the installer needing only to cut the required opening in the deck or floor of the vehicle in which the table is being installed, run appropriate wiring, and secure the table and its mechanism and receptacle in place.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates generally to permanently installed, built-in furnishings having configurations convertible between a deployed and a stored condition. More particularly, the present invention relates to a retractable table having a telescoping central column and cantilevered table platform extending to all sides therefrom, with the column comprising a relatively large number of relatively short sections. This enables the present table and its support column to retract into a relatively shallow depth, for compact installation and storage.  
         [0003]     2. Description of the Related Art  
         [0004]     Recreational vehicles, including boats as well as road vehicles, have become increasingly popular as families with sufficient time and disposable income indulge their desire to travel. In the past, most such vehicles were relatively primitively equipped, often requiring their occupants to cook their meals over an outdoor campfire and to sleep in sleeping bags. However, there has been a tendency to provide greater luxury and accommodations in such boats and road vehicles, including standard beds, kitchenettes with complete cooking and cleaning facilities, bathroom facilities, etc.  
         [0005]     Such additional accommodations, of course, require additional space, and space is already at a premium in most such vehicles, particularly those of smaller size. As a result, most of the components which require a relatively large area when deployed are configured to fold for storage when not in use. In other cases, components are engineered to provide multiple functions. An example of such is a dining table and seating arrangement, which can be folded flat for use as a double bed. In many cases, beds and seating fold out of the way when not in use.  
         [0006]     Even so, still greater utility and function might be provided with furnishings which are better engineered for retraction when not in use. The present invention provides a table surface which is supported by a single central telescoping column, with the column comprising a relatively large number of fairly short sections. This enables the present table to retract into a recess which requires very little depth, to avoid the need to penetrate the hull or other structure of the vessel or vehicle for installation of the present table. The present retractable table is well suited for installation in a variety of different types of recreational vehicles, but is particularly well suited for installation in boats, where its supporting column fixes the table in place and precludes movement when deployed. Different extension and retraction mechanisms or principles may be provided for the operation of the present retractable table.  
         [0007]     A discussion of the related art of which the present inventors are aware, and its differences and distinctions in comparison to the present invention, is provided below.  
         [0008]     U.S. Pat. No. 928,726 issued on Jul. 20, 1909 to Guy H. Witthaus, titled “Disappearing Table,” describes a table having opposed, inwardly folding leg trusses at each end thereof. The leg trusses fold inwardly, with the table resting level atop the folded trusses for storage. The leg truss arrangement precludes the extension of a person&#39;s legs beneath the table, when seated at either end thereof. The extension and retraction of the Witthaus table is by manual means; no automated or powered extension or retraction is disclosed.  
         [0009]     U.S. Pat. No. 3,391,960 issued on Jul. 9, 1968 to Robert J. Megargle et al., titled “Motor Vehicle Interior,” describes a relatively small table secured to an offset, generally vertical column having limited telescoping capability. The Megargle et al. table can be pivoted about its column for positioning between the two front seats of a vehicle, or in front of or between either of the rear seats. The device cannot retract below a height somewhat above the seating surface of the front seats, for use as an armrest between the two front seats. The entire assembly installs atop the floor of the vehicle, rather than being set into the floor, as in the present retractable table.  
         [0010]     U.S. Pat. No. 4,019,443 issued on Apr. 26, 1977 to Ferris E. Jones, titled “Table,” describes a non-retracting table in which the table base extends horizontally to a swivel attachment at the base of an adjacent seat. The entire table and support may be swiveled upwardly to place the table against the seat to which it is attached by the swivel base, for ease in accessing the other seating. No retraction means is provided.  
         [0011]     U.S. Pat. No. 4,086,859 issued on May 2, 1978 to George V. Dondero, titled “Boat Table,” describes a table having a single offset support post, allowing the table to be positioned asymmetrically about the base of the support as desired. The base of the support post may be removably secured to the underlying structure by one or more brackets. No retraction means, either powered or manual, is provided by Dondero for his table.  
         [0012]     U.S. Pat. No. 4,130,070 issued on Dec. 19, 1978 to Cline E. Herrin, titled “Linearly Translatable Table Top,” describes a table which can translate horizontally atop a fixed base pedestal. No retraction is provided for the pedestal or tabletop attached thereto.  
         [0013]     U.S. Pat. No. 4,455,948 issued on Jun. 26, 1984 to Israel Torres, titled “Automotive Trunk Table,” describes a table which extends from the floor of the trunk of an automobile on a pair of parallel pantograph arms. The device does not retract into or flush with the floor structure, and no single telescoping vertical support column is provided, as such a structure would preclude the lateral movement of the table to the rear of the vehicle, as provided by Torres.  
         [0014]     U.S. Pat. No. 4,577,821 issued on Mar. 25, 1986 to Torbjörn Edmo et al., titled “Lifting Table,” describes a table having a scissor-type support structure, rather than the single, multiple section telescoping support post of the present table. No retraction flush with or inset into a floor structure is disclosed by Edmo et al.  
         [0015]     U.S. Pat. No. 4,620,741 issued on Nov. 4, 1986 to Jacobus N. Hanemaayer, titled “Combination Table Support And Trunk Access System For A Recreational Vehicle,” describes an essentially fixed table deployed over a subfloor storage area. The table includes a primary support leg and a secondary brace which extends over the storage area. No retraction of the table into the storage area, or other area, is provided.  
         [0016]     U.S. Pat. No. 5,031,563 issued on Jul. 16, 1991 to Vigbjörn Matre, titled “System For Utilizing Raisable And Lowerable Berths In Compartments Having A Limited Space,” describes a large number of embodiments of chair, table, and berth arrangements and configurations for use in boats, camper vans, truck tractors, and railroad cars. The table configuration disclosed folds downwardly onto (but not into) the floor on a pair of fixed length, parallel legs which pivot from the vertical to the horizontal with the table remaining secured thereto. No telescoping support column is provided for the table.  
         [0017]     U.S. Pat. No. 5,069,142 issued on Dec. 3, 1991 to Vigbjörn Matre, titled “Collapsible Table,” describes two different embodiments of such a table, with one of the table embodiments being essentially the same as that described immediately above in the &#39;563 U.S. patent to the same inventor, but disclosed in greater detail. The other embodiment has support legs forming an X pattern when deployed, and which fold similarly to a conventional ironing board or the like. No single telescoping support leg having a relatively large number of segments is provided by Matre in either of his two U.S. patents.  
         [0018]     U.S. Pat. No. 5,116,032 issued on May 26, 1992 to Julie Strachan, titled “Rollingtable With Height Adjustment And Brake Device,” describes an operating table or the like having a hydraulic system providing limited vertical adjustment. The table is supported on casters, rather than being permanently installed, as is the present table. The hydraulic system forces the base downwardly against the underlying surface to preclude movement of the table when raised. The device is incapable of folding or retracting into a floor receptacle.  
         [0019]     U.S. Pat. No. 5,220,698 issued on Jun. 22, 1993 to Keith Hannant, titled “Patient Support Tables,” describes another operating table using the same principle and system as that of the Strachan &#39;032 U.S. patent discussed immediately above. It is noted that the assignee is the same for both the Strachan &#39;032 and Hannant &#39;698 U.S. patents. The same points of distinction noted in the discussion of the Strachan &#39;032 U.S. patent are seen to apply here as well.  
         [0020]     U.S. Pat. No. 5,437,236 issued on Aug. 1, 1995 to Harold R. Zeiner, titled “Multi-Functional Table With Elevational Capabilities,” describes a table having a pneumatically adjustable primary support column, with a pair of opposed brace columns. Only two sections are disclosed for each of the columns, which means that the table can only be lowered to about half of its fully extended height. The table cannot be completely lowered in any event, as a foot pedal is provided at the base of the primary column, for pumping up the column. Access to this pedal must be provided beneath the table.  
         [0021]     U.S. Pat. No. 5,503,086 issued on Apr. 2, 1996 to D. Stephen Hoffmann et al., titled “Table With Movable Top Surface,” describes a coffee table type structure in which the top surface may be extended on opposed pairs of parallel arms, somewhat like the tables disclosed in the &#39;563 and &#39;142 U.S. patents to Matre, discussed further above. The Hoffman tabletop can also rotate about its attachment to the underlying support structure. Hoffman fails to provide any means of retracting his table top into a recess in the underlying floor, however, and does not provide any form of substantially vertical, telescoping support column.  
         [0022]     U.S. Pat. No. 5,947,416 issued on Sep. 7, 1999 to John R. Kraft, titled “Floor Rising Cabin Table,” describes a pair of embodiments of a retractable table configured for use in corporate aircraft, which typically have relatively little interior room. The primary embodiment utilizes a telescoping tube for support, but the tube has only two, or at most three, different segments. The result is a relatively deep installation, with the lower end of the telescoping tube extending through the pressure vessel or hull of the aircraft and into the lower wing center section, as shown in  FIG. 12  and described in column  13 , lines  29 - 57 .  
         [0023]     Such an installation would be a major effort, as penetration of the pressurized structure of an aircraft involves major engineering considerations and work. The cost of the labor in such an installation would likely be many times the cost of the table and mechanism itself. Moreover, the lower wing center sections of such aircraft generally include fuel tanks or baggage storage areas, and the support column of the Kraft retractable table would extend into these areas.  
         [0024]     Kraft goes on at the bottom of column  13  to the top of column  14  to state that a mechanical screw or worm gear support structure could be configured to fit entirely within the pressure vessel. However, he does not disclose such a mechanism, and the only such mechanisms known to the present inventors require relatively deep receptacles, unless they use a mechanism as developed by the present inventors and disclosed herein. Moreover, Kraft fails to provide any means to prevent the rotation of the table surface about the cylindrical telescoping column, as the table is raised and lowered. The rectangular configuration of the folded table of Kraft, must be aligned with its receptacle when being retracted into the floor. Kraft would require the tabletop to be rotated by hand for alignment with the floor receptacle.  
         [0025]     The present retractable table avoids these problems by (1) providing a telescoping column formed of a relatively large number of relatively short sections, thereby requiring a very shallow depth when retracted, and (2) including alignment means for all of the column segments and their supported table top, thereby assuring that the table top will remain aligned with its receptacle when retracted. In addition, the drive means for extending and retracting the table support column is preferably provided with the remainder of the mechanism for the present invention, as an integral package. Kraft fails to disclose any specific means for actuating his table, other than mere mention of a list of known principles.  
         [0026]     U.S. Patent Application Publication No. 2001/13,307 published on Aug. 16, 2001, titled “Safety Toe-Sensor For Lift Table,” describes a lifting device wherein the lift surface is raised and supported by a pair of parallel X configuration arms, similar to the apparatus of the &#39;821 Edmo U.S. patent discussed further above. The same points raised in the discussion of the Edmo U.S. patent, i.e. the lack of a central telescoping column and lack of means for retracting so the table top is flush with the surrounding floor, are seen to apply here as well.  
         [0027]     British Patent Publication No. 1,559,945 published on Jan. 30, 1980, titled “Operation Table,” describes a portable table for medical use, e.g. X-ray examinations or operations. The table actually comprises a series of platform sections that may be angularly adjusted relative to one another, but their height above the base is essentially fixed atop a fixed pedestal. No vertical retraction or extension mechanism is disclosed, and the portable nature of the table does not permit retraction into a floor receptacle.  
         [0028]     PCT Patent Publication No. WO 87/5272 published on Sep. 11, 1987, titled “Cockpit Table For Boats,” describes a table mounted on a swivel arm. The arm extends horizontally from a bracket, and rotates about its swivel mounting. The table attaches to the distal end of the arm, by a swivel mounting. While the table and its bracket can be removed from a permanent wall mounted anchor, no retraction means is disclosed.  
         [0029]     PCT Patent Publication No. WO 88/10,081 published on Dec. 29, 1988, titled “Table Having A Table Board The Height Of Which Is Adjustable,” describes an elevated table extending upwardly on a pedestal from a lower stand. The stand includes a mechanism for raising the table as desired, and a locking mechanism for fixing the height of the table as desired. The table may only be lowered to the top of the stand; the stand rests atop the underlying surface. No retraction flush with the underlying surface is possible with the table.  
         [0030]     Japanese Patent Publication No. 64-53,999 published on Mar. 1, 1989, titled “Table Lift,” describes (according to the drawings and English abstract) a scissor type lifting arrangement, with one of the arms comprising a hydraulic cylinder. The mechanism can lie relatively flat beneath the table, due to a starting linkage which initiates the table lift when the system is actuated. This provides some initial angle for the operation of the hydraulic lift strut to work. While the assembly can fold to a quite thin and compact configuration, no vertical telescoping column is provided, nor is any means of installing the device to lie flush with the floor of a structure, as provided by the present retractable table.  
         [0031]     Japanese Patent Publication No. 2-175,595 published on Jul. 6, 1990, titled “Lifting Table,” describes (according to the drawings and English abstract) a table and lifting mechanism recessed into a lower surface or pit. A telescoping hydraulic cylinder is used to provide the lifting force. However, the hydraulic mechanism comprises only two segments and cannot be collapsed to a sufficiently short height as to fit within the confines to which the present retractable table is directed. Moreover, no means of preventing relative rotation between the upper and lower portions of the hydraulic cylinder is apparent in the &#39;595 Japanese Patent Publication.  
         [0032]     Finally, British Patent Publication No. 2,242,624 published on Oct. 9, 1991, titled “Operating Table,” is based upon the &#39;032 U.S. patent to the same inventor, discussed further above. Accordingly, the same points raised in the discussion of the &#39;032 U.S. patent are seen to apply here as well.  
         [0033]     None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus a retractable table solving the aforementioned problems is desired.  
       SUMMARY OF THE INVENTION  
       [0034]     The present retractable table provides a compactly folding or retracting article for installation in boats, recreational vehicles, and cabin-size corporate aircraft, as desired. A key feature of the present retractable table is its multi-segmented telescoping support strut. Rather than being formed of two, or perhaps three, sections, the support strut for the present folding table is formed of a larger number of shorter sections, enabling the table to extend to full height above the supporting surface and still retract compactly in a very shallow receptacle.  
         [0035]     Various means for actuating the present retractable table, including hydraulic and helically threaded mechanical systems, are described herein. In both systems, appropriate seals and stop means are provided in order to preclude overextension of any given pair of mating segments. Appropriate means for preventing relative rotation between extension segments is also provided, assuring that the table remains aligned at all times with the receptacle in which it retracts.  
         [0036]     The present retractable table is most preferably configured as a “drop-in” assembly, including a shallow well or receptacle which may be installed in a cutout in the floor or deck of the vehicle, boat, or aircraft in which the device is installed. The installer need only form the required cutout in the surface in which the present invention is to be installed, run the appropriate electrical power and control wiring to the installation area, secure the device within the cutout opening, and connect the wiring. The hydraulic embodiment of the present retractable table includes a hydraulic pump and motor power pack as an integral unit therewith, thus obviating the need for a separate hydraulic system and plumbing.  
         [0037]     The present retractable table meets the needs of persons having cabin class boats and aircraft, as well as those with recreational vehicles, where space is at a premium. The present table is easily extended by actuation of a switch or the like, to serve as a table for dining, chart work, games, or other activities as desired. When the table is no longer needed, it is easily stored by retracting into its well in the floor.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0038]      FIG. 1  is a schematic side elevation view in partial section of a hydraulically operated embodiment of the retractable table according to the present invention in an extended state, showing its various features.  
         [0039]      FIG. 2  is a schematic side elevation view in partial section of the retractable table of  FIG. 1  in a retracted state.  
         [0040]      FIG. 3A  is a top plan view in section of an embodiment of the multi-segment hydraulic lifting column of the table of  FIGS. 1 and 2 , showing the means for preventing relative rotation of the column segments.  
         [0041]      FIG. 3B  is a top plan view of a broken away section of an alternative embodiment lifting column, showing alternative means for preventing rotation of the segments relative to one another.  
         [0042]      FIG. 4  is a schematic side elevation view in partial section of an embodiment incorporating a number of helically threaded column segments for raising and lowering the table.  
         [0043]      FIG. 5  is a perspective view in section of the helically threaded column of  FIG. 4 , showing the mutually engaging ends of the segments for preventing overextension of mating segments.  
     
    
       [0044]     Similar reference characters denote corresponding features consistently throughout the attached drawings.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0045]     The present invention comprises several embodiments of a retractable table, suited for permanent (or semi-permanent) installation in the floor or similar structure of a cabin class boat, aircraft, or recreational vehicle. The present retractable table generally includes a base which is installed in a cutout formed in the vehicle floor, with a single, multiply segmented telescoping lift strut extending upwardly from the base to support a table top thereon. The relatively large number of lift strut segments result in each segment being relatively short, allowing the lift strut and table to retract flush with the floor without requiring any substantial depth below the floor for the retracted lift strut.  
         [0046]      FIG. 1  of the drawings provides a schematic side view in partial section of a first embodiment of the present retractable table apparatus in its extended configuration, designated by the reference numeral  10 . The present retractable table assembly  10  is configured for permanent, or at least semi-permanent, installation in the deck D or floor of a cabin class boat or yacht, a cabin class aircraft, or recreational vehicle. A floor installation base  12  includes a peripheral floor attachment flange  14 , which secures atop the deck D or floor using conventional fasteners or other suitable attachment means. The flange  14  preferably tapers outwardly to a thin edge, in order to avoid forming a tripping hazard. The installation base  12  has a shallow tabletop recess  16  located just below the upper surface  18  of the flange  14 , for receiving the table  20  of the present invention when it is retracted. The tabletop recess  16  is dimensioned to closely fit the table  20 , with the cutout formed in the deck D preferably dimensioned to fit closely about the exterior of the tabletop recess  16  in the installation base  12 .  
         [0047]     The installation base  12  further includes a lift strut receptacle  22  in the tabletop recess portion  16  thereof, and depending below the tabletop recess  16 . The lower end of the lift strut for the tabletop  20  is affixed within this lift strut receptacle  22 . The lift strut  24  is formed of a relatively large number of relatively short, concentric, telescoping sections or segments, e.g. a lower or base segment  24   a  affixed within the lift strut receptacle  22 , a series of five intermediate strut segments  24   b  through  24   f  which are extendable from the base segment  24   a , and an uppermost segment  24   g  to which the table top  20  is affixed. More or fewer lift strut segments may be provided as desired, depending upon the height requirement for the extended tabletop  20  and the depth limitation for the lift strut receptacle  22 . However, a series of seven such lift strut segments  24   a  through  24   g  has been found to provide a suitable compromise in lift height and depth of the retracted mechanism, without requiring undue complexity.  
         [0048]     Preferably, the lift strut assembly  24  comprises a series of concentric hydraulic cylinders, with conventional seals disposed between each segment. A power package comprising a hydraulic pump  26  and fluid reservoir  28  is situated beneath the floor installation base  12 , e.g. secured to the lift strut receptacle  22 , and provides hydraulic fluid under pressure by means of inlet and outlet lines  30  and  32  between the pump  26  and the base cylinder or segment  24   a . A conventional electric motor and remote switch (not shown) may be used to actuate the pump  26  as desired to extend or retract the column  24  and table  20 .  
         [0049]      FIG. 2  of the drawings provides an elevation view in partial section of the retractable table mechanism  10  in its retracted state. In  FIG. 2 , the central lift strut  24  has been collapsed or retracted, with the smaller diameter segments nesting within the larger diameter segments. The segments forming the outer sleeve assembly  34  are nested in the same manner. The large number of relatively short segments forming the lift strut  24  and outer sleeve assembly  34 , allow the table top  20  to be retracted so that its upper surface  36  is flush or essentially coplanar with the upper surface  18  of the peripheral mounting flange  14  of the floor installation base  12 , while still providing a relatively shallow depth for the lift strut receptacle  22  and its removable access cover  38 .  
         [0050]     As the hydraulic cylinder segments  24   a  through  24   g  are circular in cross section, there is nothing per se to preclude relative rotation of any of the cylinder segments relative to one another. This may not be critical in the case of a round table  20  and correspondingly shaped circular table receptacle  16  in the installation base  12 , but it is important where a non-circular tabletop  20  and correspondingly shaped recess  16  are provided. Accordingly, the present retractable table mechanism  10  includes an outer sleeve assembly  34 , as noted above, which serves to maintain the alignment of the tabletop  20  with its underlying recess  16 . The outer sleeve assembly  34  comprises a base sleeve  34   a  (which may be the same as the lift strut receptacle  22 ), a series of concentric, telescoping intermediate sleeves, e.g. sleeve segments  34   b  through  34   f , and an uppermost sleeve segment  34   g . Preferably, the number of outer sleeve segments  34   a  through  34   g  is the same as the number of hydraulic cylinder segments  24   a  through  24   g , although the limiting factor for the extension and retraction height of the assembly  10  is the length of the longest cylinder or sleeve segment, if they are not of equal length.  
         [0051]     The series of outer sleeve segments  34   a  through  34   g  each include some form of cooperating linear engagement means to preclude relative rotation between each of the immediately adjacent segments, and thus between the lift strut receptacle  22  comprising the lowermost outer sleeve segment  34   a  and the uppermost outer sleeve segment  34   g  with its attached table top  20 .  FIGS. 3A and 3B  illustrate examples of such anti-rotation means. In  FIG. 3A , a series of outer sleeve segments  34   a  through  34   g  concentrically surround the inner lift strut segments  24   a  through  24   g . The outer sleeve segments  34   b  through  34   g  all include at least one (and preferably two or three) linear channel(s)  40  formed in their outer walls, with the segments  34   a  through  34   f  all having corresponding linear ribs  42  formed along their inner walls and engaging the corresponding channels  40  of the inwardly adjacent segments. The engagement of the channels  40  and ribs  42  prevent relative rotation between adjacent segments, thus preventing rotation of the innermost segment  34   g , and its attached table top  20  (shown in  FIGS. 1 and 2 ) relative to the outermost base segment  34   a . It will be seen that the orientation of the channels and ribs may be reversed if so desired, with the ribs extending outwardly and channels extending inwardly, or other engagement means may be used as desired.  
         [0052]      FIG. 3B  provides a broken away plan view in section of an alternative outer sleeve assembly of non-circular cross section, designated as sleeve assembly  35 . The inner hydraulic cylinder assembly  24 , comprising segments  24   a  through  24   g , is essentially identical to the assembly  24  shown in  FIGS. 1 and 2 . However, the outer sleeve assembly  35  is formed of a series of non-circular segments  35   a  through  35   g , with each of the segments having the same non-circular shape and being progressively smaller to fit closely within one another. (It should be noted that clearances between segments  24   a  through  24   g  and  35   a  through  35   g  in  FIG. 3B , and clearances between segments  24   a  through  24   g  and  34   a  through  34   g  in  FIG. 3A , are exaggerated for clarity in the drawing Figs.) The non-circular configuration of the outer sleeve segments may be square, as shown, or may alternatively be of any regular or irregular shape as desired, so long as they share the same shape but vary progressively in size from the largest to the smallest segment, in order to fit closely with one another and preclude relative rotation of any of the segments.  
         [0053]     To this point, a hydraulic operating system has been described for extending and retracting the table top of the present invention. However, it will be seen that other actuating mechanisms may be provided, as desired. One such mechanism may comprise a series of concentric, helically threaded segments  124   a  through  124   g  forming a threaded lift strut  124 , as illustrated in  FIG. 4  of the drawings. An outer sleeve assembly, e.g. sleeve assembly  34  comprising segments  34   a  through  34   g , is provided to prevent rotation of the table top  20  relative to the base  12  and its table top recess  16 . The helically threaded lift strut assembly  124  operates by means of an electric (or alternatively, hydraulic) motor  44 , which communicates with a drive wheel  46  extending from the lower end of the first helical segment  124   a . Conventional belt or chain drive, gearing, etc. (not shown) may be used to connect the rotation of the motor  44  to the lift strut drive wheel  46 . (Such an electric motor  44  may also be used to drive the hydraulic pump  26  of the hydraulically actuated embodiment of  FIGS. 1 and 2 .)  
         [0054]     The helically threaded lift strut embodiment of the present retractable table is illustrated in its extended or deployed position in  FIG. 4 . From an initial stored or retracted configuration, rotation of the drive wheel  46  also rotates the first helically threaded segment  124   a , which causes the second segment  124   b  to unthread from its stored position within the first segment  124   a . When the second segment  124   b  has reached the end of its threaded extension from the base segment  124   a , it will also be forced to rotate, thereby causing the third segment  124   c  to unthread from the second segment  124   b . This sequential unthreading operation will continue until all of the lift strut segments  124   a  through  124   g  have unthreaded themselves from one another to their limits, thus causing the table top  20  to rise to its fully deployed position as shown in  FIG. 4 . While the unthreading of the segments  124   a  through  124   g  has been described as a sequential operation, it should be noted that the order of relative rotation may vary depending upon friction between segments, and is not critical.  
         [0055]     It will be understood that some means is required for preventing the overextension of the various segments, in order to prevent segments from disassembling from one another as they extend.  FIG. 5  provides a detailed perspective view in section of the outer sleeve assembly  34  and its segments  34   a  through  34   g , as well as the helically threaded lift strut  124  and its segments  124   a  through  124   g , showing the overextension stop means provided. Each of the outer sleeve segments  34   a  through  34   f  includes an upper, inwardly extending flange  48 , with each of the segments  34   b  through  34   g  having a lower, outwardly extending flange  50  of smaller inner diameter than the outer diameter of the corresponding opposite flange  48 . Thus, when the outer sleeve  34  extends to its maximum height, each of the outer flanges  48  is prevented from overextension by its contact with the overlying inner flange of the next sleeve unit or segment. This same principle may be used to limit the extension of the hydraulic strut assembly  24  shown in  FIGS. 1 and 2 , as well, or other overextension stop means (e.g., conventional grooves with internal and/or external snap rings, etc.) may be used.  
         [0056]     Overextension of the helically threaded lift strut segments  124   a  through  124   g  is prevented in much the same manner, with each of the segments  124   a  through  124   f  having an upper, inwardly extending flange  52  and each of the segments  124   b  through  124   g  having a lower, outwardly extending flange  54 . Alternative overextension prevention means may be used, as noted above in the description of such means for the lift strut  124 . However, each of the inwardly extending flanges  52  of the helically threaded lift strut segments  124   a  through  124   f  includes internal threads  56 , which engage the external threads of the adjacent inner lift strut segment. In this manner, rotation of any lift strut segment relative to its immediately adjacent lift strut segment results in the extension or retraction of the two segments relative to one another, depending upon the relative direction of rotation.  
         [0057]     As noted further above, the rotational extension or retraction of the helically threaded segments  124   a  through  124   g  may be sequential, or in some other order, depending upon relative friction between adjacent segments. However, the order of extension or retraction is not critical, as when any two segments have reached their fully extended state, the abutting outward and inward flanges  52  and  54  of any two mating segments prevent further extension and cause the two segments to rotate together as one unit, thereby transferring relative rotation to other segments of the assembly until extension is complete.  
         [0058]     While not shown in the drawings, additional lower, inwardly extending flanges or upper, outwardly extending flanges may be provided opposite their counterparts  48 ,  52  and  50 ,  54  on the outer sleeve segments  34   a  through  34   g  and the lift strut segments  124   a  through  124   g  (or the hydraulic lift strut segments  24   a  through  24   g  of  FIGS. 1 and 2 ). This serves to prevent the higher segments from dropping through the lower and larger diameter segments, when the assemblies are retracted. Again, other means may be used, e.g. circumferential grooves and snap rings, etc.  
         [0059]     In conclusion, the present retractable table in its various embodiments provides a much needed means of creating a table for dining, chart work, games, or any other suitable purpose, which may be retracted into the floor for unobtrusive storage when not needed. A simple throw rug or the like may be spread over the retracted table surface when floor space is needed, in order to protect the table surface when retracted. Alternatively, folding extension leaves may be provided from the edges of the table to expand the surface area of the table when in use, with the leaves folding over the top of the table to protect the table surface when retracted into the floor. The present retractable table assembly is easily installed, as it is provided in an installation base which is easily secured within the floor, once the appropriate cutout has been formed in the floor. Accordingly, the present retractable table will be favorably received by owners of cabin class boats and aircraft, recreational vehicles, and others who have need for a retractable table surface within a confined area.  
         [0060]     It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.