Abstract:
A type of backyard or playground recreational equipment usable indoors or outdoors. The present invention provides a bent springpole that functions much like the naturally-occurring feature that has been a recreational favorite of children for centuries, a low-hanging tree limb. The springpole provides the vertical bouncing motion of a tree limb, as well as a 360 degree rotational motion. Children and adolescents are able to bound, bounce, and run in a limited amount of space. The pole can be equipped with padding in whimsical shapes, a seat, and steps.

Description:
[0001]     This application claims priority from provisional application 60/674,886 filed Apr. 26, 2005. The present invention relates to the field of recreational equipment. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     Exercise devices from which users may suspend themselves are not new. In U.S. Pat. No. 3,837,641, Hanson describes an exercise device consisting of a bent, rotateable swing bar. For its vertical motion, Hansen&#39;s bar depends on a fixed angle between the bar and vertical, thus subjecting a user to the risk of collision with the bar at its highest position as illustrated by the phantom configuration of user  28 ′and bar  14 ′ in  FIG. 12  of the &#39;641 patent The present invention utilizes a vertical support and a spring steel pole to enable a user to achieve vertical motion throughout a 360 degree rotation without risk of the hazards associated with collision with a rigid bar.  
         [0003]     For support, Hansen&#39;s device depends entirely on a stake  32  driven into the ground at an angle (see the &#39;641 patent, column 2, lines 13-21). The present invention provides support means inherently more resistant to the various forces and torques that will inevitably be imposed on such recreational devices.  
         [0004]     Hansen states that one of his objectives is to provide a bar the rotation of which is damped by immersion in a damping medium (see the &#39;641 patent, column 1, lines 39-47). Hansen furthermore includes damping means in all six claims. The present invention dispenses with the inconvenience, inconsistency, deterioration, and expense of Hansen&#39;s damping media with reliance on the mechanical friction inherent in the simple relative motion between two concentric cylinders.  
         [0005]     In U.S. Pat. Nos. 3,480,274 and 3,246,893, Boggild describes a gymnastic device consisting of an anchored fiberglass pole (see the &#39;274 patent, column 2, lines 35-38, and the &#39;893 patent, column 2, lines 53-60, wherein Boggild teaches away from a steel pole). Because of the brittle nature of fiberglass, Boggild goes to great length to describe a complicated dual-support mounting scheme that depends on unpredictable and notoriously short-lived elastomers (see &#39;274 patent, column 2, lines 64-66 and column 3, line 10 through column 4, line 20). The spring steel pole of the present invention preferred embodiment obviates such expensive assemblies and provides longer life than the Boggild device. Also, because fiberglass is highly susceptible to abrasion and splintering, Boggild requires that a thin vinyl sheath be glued to his pole (see the &#39;274 patent, column 4, lines 21-26). The present invention does not require the extra manufacturing complication, expense, and wear problems associated with a sheath.  
         [0006]     Because Boggild&#39;s poles are not intended to rotate (see the &#39;274 patent, column 3, lines 14-23, and the &#39;893 patent, column 3, lines 49-50), a user is limited in recreational options, or, if a user forces the pole to bend around a circle, the user&#39;s grip on the pole must be constantly changing to compensate for the dangerous tendency of the pole to twist against the imposed torque and dislodge itself from the user&#39;s hands. The present invention eliminates this unpleasantly limiting safety hazard.  
         [0007]     Moreover, all six of Boggild&#39;s &#39;274 claims limit his device to include “a damping means fixed to said pole” (see the &#39;274 patent, column 6, line 20 and subsequent dependent claims). The present invention dispenses with the manufacturing complications and expense of Boggild&#39;s damping means.  
         [0008]     In the &#39;893 patent, Boggild limits his claims to spaced-apart bearing surfaces. No such bearings are required by the present invention. Also, Boggild&#39;s devices, because they are built on a straight, vertically mounted pole, suffer from the same safety hazard inherent in the Hanson design, i.e. the probability of user collision with the pole during use.  
         [0009]     Therefore, for all the abovementioned reasons, current art does not contain all the features claimed by the present invention. The present invention offers enhanced usefulness, longer life, and less expense than the prior art The present invention also presents fewer safety hazards than the prior art. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     In all the accompanying drawings like features are labeled with like identifying numbers.  
         [0011]      FIG. 1  is a perspective view of the preferred embodiment of the present invention.  
         [0012]      FIG. 2  is a perspective view of the preferred embodiment of one feature of the preferred embodiment of the present invention.  
         [0013]      FIG. 3  is a cutaway perspective drawing of the feature depicted in  FIG. 2 .  
         [0014]      FIG. 4  is a perspective drawing of an alternate embodiment of the feature depicted in  FIGS. 2 and 3 .  
         [0015]      FIG. 5  is a perspective view of the preferred embodiment of one feature of the preferred embodiment of the present invention.  
         [0016]      FIG. 6  is a frontal view of an alternate embodiment of the present invention.  
         [0017]      FIG. 7  is an enlarged cross sectional view of a portion of the alternate embodiment depicted in  FIG. 6 .  
         [0018]      FIG. 8  is a cross sectional view of an alternate embodiment of the present invention.  
         [0019]      FIG. 9  is a side view of one embodiment of one feature of the present invention.  
         [0020]      FIG. 10   a  is a partial cutaway front view of an alternate embodiment of the present invention.  
         [0021]      FIG. 10   b  is a partial cutaway side view of the alternate embodiment of the present invention depicted in  FIG. 10   a.    
         [0022]      FIG. 11  is a partial cross sectional view of on alternate embodiment of the present invention.  
         [0023]      FIG. 12  is a partial cross sectional view of on alternate embodiment of the present invention.  
         [0024]      FIG. 13  is a perspective view of on alternate embodiment of one feature of the present invention.  
     
    
     DEFINITIONS  
       [0025]     The following terms are used in the claims of the patent application as filed and are intended to have their broadest meaning consistent with the requirements of law. Where alternative meanings are possible, the broadest meaning is intended. All words and phrases are to be interpreted as they are preferentially defined in the present Specification, and then in commonly accepted English language dictionaries, handbooks, textbooks, and treatises. All words used in the claims are intended to be used in the customary usage of English language grammar.  
         [0026]     “Concentric” and “concentrically” mean having a common center, regardless of cross sectional shape.  
         [0027]     “Pad” means a mass of material used to minimize or prevent jarring, scraping, or other injury; it may be permanently attached, removeably attached, or integral to hard surfaces; it may be fashioned in any likeness, geometry, and thickness; and it may be rubber, foam, gas pockets, tape, or any other cushioning material.  
         [0028]     “Pole” means a solid or tubular, straight, curved, or coiled, relatively slender elongated member having any cross sectional geometry that may be uniform or variable along the member length; it may be metallic or non-metallic.  
         [0029]     “Spring” means any elastic device that returns to or near to its neutral, unforced configuration after being compressed, extended, bent, twisted, or otherwise disturbed; it may be metallic or non-metallic; it may be formed, extruded, stamped, molded, or otherwise manufactured.  
         [0030]     “Tube” means a conduit the lateral cross section of which is not necessarily round.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0031]     The structure and operation of the invention will become apparent upon reading the following detailed description of the preferred embodiment, the following descriptions of various alternatives thereto, and upon reference to the accompanying drawings. The inventor presents herein the best mode for carrying out the present invention in terms of its preferred embodiment, depicted within the aforementioned drawings.  
         [0032]      FIG. 1  shows preferred embodiment  90 . Steel angle  95  is welded to ground tube  94  and concreted in well  11  flush with or slightly higher than the ground  99 . Alternatively, ground tube  94  can be made part of a portable but stable base.  
         [0033]     Mast  93  is rotatably inserted into ground tube  94 . Collar  92  with its integral welded skirt is slideably and rotatably installed on mast  93  at a position just above one of the through holes in mast  93 . A hardened steel pin  12  inserted through the selected through hole then provides a stop that prevents collar  92  and its integral skirt from sliding downward on mast  93 . A cap may be fixed on top of mast  93  to prevent rainwater from penetrating the mast and ground tube.  
         [0034]     Pole  91  with welded handle  2  covered with pad  3  is fixed into pole sleeve  83  of mast sleeve assembly  80  (see  FIG. 5 ) with a cold weld epoxy adhesive such as JB Weld 2-part epoxy available at hardware stores, auto parts stores, and home repair outlets. Alternatively, pole  91  and pole sleeve  83  can be notched and joined with a commonly used Woodruff key such as those available from Wilson Mfg. Co. of Pipestone, Minn. Woodruff keys can be force-fit or welded.  
         [0035]     In the preferred embodiment, handle  2  consists of a tube or rod welded perpendicular to the distal end (outboard of mast  93 ) of pole  91 , thus forming a “T.” Alternatively, handle  2  could be one or more steel loops. Mast sleeve assembly  80  consists of collar  81 , mast sleeve  84 , web  82 , and pole sleeve  83 , all of which are steel components welded together.  
         [0036]     Mast sleeve assembly  80  and attached pole  91  are slideably and rotatably installed on mast  93  at a position just above one of the through holes in mast  93 . A pin  12  inserted through the selected through hole then provides a stop that prevents mast sleeve assembly  80  from sliding downward on mast  93 . If it is desired to position pole  91  in a particular angular location with respect to the vertical axis of mast  93 , a pin  12  can be inserted through matching holes in mast sleeve  84  and mast  93  and a pin  12  can be inserted through matching holes in mast  93  and ground tube  94 . The pins  12  will prevent rotation of mast sleeve assembly  80  and pole  91  around mast  93  and ground tube  94 . Collars  81  and  92  provide perches and climbing steps for users.  
         [0037]     Alternatively, if mast portability is not important, ground tube  94  is not necessary. Mast  93  can be concreted in well  11 , with or without reinforcing angle  95 , and rotatability of the mast sleeve assembly is not impaired.  
         [0038]     The height of pole  91  above ground  99  is adjustable. Any of the holes drilled through mast  93  at predetermined intervals can receive a pin  12 , thus allowing a user to independently adjust the height above ground of collar  92  and pole  91  (along with collar  81 ). There are seven pairs of holes (not shown), large enough to receive a ¼ inch rod or pin. The lowest hole pair is 12 inches above grade, and the other six pairs are spaced at 12 inches. Thus, the preferred embodiment of  FIG. 1  is capable of seven different heights, one for each of the three hole  10  pairs, and one with the skirt of collar  92  resting on the top of ground tube  94  or the ground.  
         [0039]     Changing the height of collar  81  or  92  requires alignment of the mounting holes in the collar with the mating mounting holes in the mast. This task can be simplified by the use of square tubing to form the collars and the sections of the mast that accommodate the collars. Collars would be made of square tubing larger than the mast section square tubing. Plastic inserts could be pressed or otherwise attached to the insides of the collars, thus filling the gaps between the collar and mast tubes, and protecting the surface finish of the mast. Mast rotatability would be preserved by using a cylindrical section of the mast inside the ground tube.  
         [0040]     In the preferred embodiment of  FIG. 1  ground tube  94  is 3½ inch diameter schedule  40  steel pipe,  24  inches long. Mast  93  is 3 inch diameter schedule  40  steel pipe, 7 feet long. Collars  81  and  92  are 12¼ inch discs of 3/16 inch steel plate with 4 inch diameter center holes. The skirt welded to collar  92  is a 3½ inch diameter schedule  40  steel pipe. Mast sleeve  84  is a 4 inch long section of 3½ inch diameter schedule  40  steel pipe. Pole sleeve  83  is a 6 inch long section of 1¼ inch extra-extra-heavy steel pipe. Web  82  is a triangular section of 3/16 inch steel plate cut to form a 70 degree angle at the intersection of pole sleeve  83  and mast sleeve  84 . The pole and mast sleeve intersection angle can be custom-fabricated to suit the user.  
         [0041]     Pole  91  is a 7 foot long section of ⅞ inch diameter 5160 spring steel. Spring steel is commonly understood to be the category of steel alloy from which leaf, rod, bar, and wire springs can be manufactured. The alloy can be displaced from an unforced or neutral configuration or position by a force, and unless the resulting stress exceeds the alloy&#39;s elastic limit or yield point, the stored energy in the alloy due to the displacement causes the alloy to return to its unforced configuration. The pole is manufactured by Coiling Technologies, 7777 Wright Road, Houston, Tex. 77041.  
         [0042]     The pole, mast, mast sleeve assembly, and collars are primed and powder coated with commonly understood processes. The ground tube is primed. Alternatively, some or all parts can be painted with industrial grade low maintenance paint.  
         [0043]      FIG. 2  depicts the preferred embodiment of pad  3 , with protruding handle  2  (see also  FIG. 1 ), installed on pole  91  of the present invention.  FIG. 3  is a cutaway drawing that shows how foam pad  3  completely encapsulates the hard surfaces of handle  2  and handle hub  18 . In the present invention preferred embodiment, handle  2  is a 0.5 inch diameter steel rod 13½ inches long inserted through holes drilled in the sidewalls and on a diameter of handle hub  18  and welded to handle hub  18 , which is a 1¼ inch diameter steel pipe 3 inches long. A steel disc  17  is welded to the open end of handle hub  18  that accommodates handle  2 .  
         [0044]     Pad  3  is then molded onto handle  2  and handle hub  18  in any moldable shape, size, and color. Disc  17  and a cylindrical slide in the pad mold opposite disc  17  prevent the entrance of foam, other molding materials, and debris into handle hub  18  during the molding operation. The mold slide also forms cylindrical tunnel  19  for receipt of one end of pole  91  subsequent to the mold operation. In the preferred embodiment, pad  3  is foam molded approximately ⅜ inches thick all around handle  2 , except for the ends of handle  2  where the thickness is approximately 1½ inches. The foam is molded approximately 1½ inches thick all around handle hub  18 . The hub section of pad  3  is therefore a cylinder with an approximate diameter of 4½ inches with bulbous ends (see  FIG. 2 ) that make the overall length of the hub section of pad  3  approximately 5 inches. The pad material of the preferred embodiment is FMS 7134 Self Skinning Polyurethane Foam prepared and molded by Foam Molders &amp; Specialties, 20004 State Road, Cerritos, Calif. 90703.  
         [0045]      FIG. 3  shows that the end of cylindrical handle hub  18  opposite from handle  2  is left open and exposed in the pad molding operation. The resultant cylindrical cavity in pad  3 , beginning with foam tunnel  19  and terminating inside handle hub  18 , provides for receipt of the distal end of pole  91 . The tip of the distal end of pole  91  has a diametrical groove or notch (not shown) just large enough to accommodate handle  2 . With handle  2  nested in the pole end groove, it will not torque itself away from the pole during use.  
         [0046]     The first approximately 5 inches of the distal end of the preferred embodiment ⅞ inch diameter pole  91  are left bare, while the adjacent approximately 24 inches of the pole distal end are wrapped with 2 inch doublesided tape that is subsequently coated with HF-100 Grip Activator. The tape and activator are generally used for wrapping golf club handles, and are available at golf equipment and pro shops. A ¼ inch thick foam grip sleeve available from Gripworks of Arnold, Mo. (stock no. 072264, FEX tubing 0.812-0.175-26.0-30.0-CPE/EPDM) is inserted over the tape while the activator is still damp and slick. For a larger pole, 15/16 inch diameter for example, a thinner grip sleeve might be required.  
         [0047]     The approximate 5 inches of bare pole end, including the notched tip of the pole, are cleaned, dried, and coated with an approximate ⅛ inch thick layer of a cold weld epoxy adhesive such as JB Weld 2-part epoxy available at hardware stores, auto parts stores, and home repair outlets. Quickly enough to prevent the epoxy from prematurely curing, the distal end of pole  91  is press fit into the opening in pad  3  until it bottoms out in handle hub  18  with handle  2  nested in the pole tip notch. After the epoxy cures according to manufacturer&#39;s specifications, handle  2 , pad  3 , and pole  91  become an integral assembly.  
         [0048]     Alternatively, hub  18  and the distal end of pole  91  can be notched with transverse half-round grooves that align when pole  91  is bottomed out inside hub  18 . Handle  2  can then be fitted into the aligned grooves and welded to the hub groove, thus causing handle  2  and hub  18  to be permanently attached to each other. Handle  2  then acts as a Woodruff key to prevent a user from pulling the hub and handle off of pole  91 .  
         [0049]      FIG. 4  illustrates one of many possible variations of pad  3 . The variation illustrated gives the user the option of sitting on pad  3  as well as gripping and hanging from handle  2 .  
         [0050]      FIG. 6  illustrates one of many possible alternatives  100  to the present invention preferred embodiment  90 . Curved pole  1  with welded “T” handle  2  covered with pad  3  is rotateably inserted into the inner diameter of cylindrical support tube  4  that is part of a support tube assembly made of tubes  4 ,  6 , and  9 , collars  5 ,  7 , and  8 , and rod  14 . As in the preferred embodiment, handle  2  can have many configurations other than the “T” design. Support tube  4  is welded to cylindrical support tube collar  5  that is in turn welded to cylindrical intermediate tube  6 . Intermediate tube  6  is welded to cylindrical intermediate tube collar  7 , which is welded to cylindrical intermediate tube skirt  8 .  
         [0051]     Intermediate tube collar  7  and intermediate tube skirt  8  are concentric to intermediate tube  6  and do not block the inner diameter of intermediate tube  6 . Intermediate tube  6  is therefore able to receive cylindrical ground tube  9 , the outer diameter of which is slightly smaller than the inner diameter of intermediate tube  6 .  
         [0052]     If it is desired to position pole  1  in a particular angular location with respect to the vertical axis of the support tube assembly, pin  12  inserted through matching holes in support tube  4  and pole  1 , and retained by clip  13 , can be used. Pin  12  will prevent rotation of pole  1 .  
         [0053]     Collars  5  and  7  provide perches and climbing steps for users. Ground tube  9  can be set in a concrete well  11  in the ground  99  or made part of a portable but stable base.  
         [0054]     The height of pole  1  above ground  99  is adjustable. Any of the holes  10  through ground tube  9  can receive a hardened steel rod  14  that is slightly shorter than the inside diameter of intermediate tube skirt  8 .  FIG. 7  shows that with rod  14  centered in ground tube  9  through a hole  10 , intermediate tube  6 , complete with attached collars  7  and  8 , can be slideably lowered onto ground tube  9  until the underside of intermediate tube collar  7  (welded to intermediate tube  6 ) rests on rod  14  with intermediate tube skirt  8  (welded to intermediate tube collar  7 ) shielding rod  14  from accidental user access. With collar  7  resting on rod  14 , rod  14  is captured; its length prevents its movement beyond the inner diameter of intermediate tube skirt  8 . Thus rod  14  cannot accidentally be vibrated out of hole  10  and can only be removed when intermediate tube  6  is raised high enough for rod  14  to clear tube skirt  8 . A sufficiently long pin  12  that can be retained with a clip  13  can be used as an alternative to rod  14 .  
         [0055]     In the alternate embodiment of  FIG. 6  ground tube  9  is 1½ inch diameter schedule  80  steel pipe, 5 feet long with 2 feet below grade. There are three pairs of holes  10 , large enough to receive a 7/16 inch rod or pin. The lowest hole pair is 12 inches above grade, and the other two pairs are spaced at 12 inches. Thus, the alternate embodiment of  FIG. 6  is capable of four different heights, one for each of the three hole 10 pairs, and one with intermediate tube skirt  8  resting on the ground.  
         [0056]     Intermediate tube skirt  8  is a 2 inch long section of 8 inch diameter steel pipe. Intermediate tube collar  7  is a 9 inch diameter disc cut from ⅛ inch thick steel plate, and has a center hole the diameter of which is between the inner and outer diameters of intermediate tube  6  that is a 3 foot section of 2 inch diameter schedule  80  steel pipe. Support tube collar  5  is a 9 inch diameter disc cut from ⅛ inch thick steel plate. Support tube  4  is a 6 inch section of 1¼ inch diameter extra-extra-heavy grade steel pipe.  
         [0057]     Pole  1  is ⅞ inch diameter 5160 spring steel. It is manufactured by Coiling Technologies, 7777 Wright Road, Houston, Tex. 77041. A seven foot long piece is bent in a hot oil bath to an angle between 90 and 140 degrees, beginning at a point approximately 12 inches from one end. The bend radius is 4 feet. The pole is primed and powder coated with commonly understood processes.  
         [0058]      FIG. 8  illustrates one of many possible alternatives to the present invention preferred embodiment. In apparatus  200 , curved pole  1 , the same or a similar pole as described as part of the alternate embodiment  100 , is utilized in a support tube assembly different from that of the alternate embodiment  100 . Cylindrical steel ground tube  70  is concreted in the ground  99  or made part of a portable but stable base. Cylindrical steel standpipe  60  provides rigid support for cylindrical steel couplings  20 ,  30 ,  40 , and  50 , all of which are capable of rotation around the center axis of standpipe  60 . Curved pole  1  is capable of rotation inside coupling  30 . Collars can be attached to tubes  20  and  40  to provide perches and climbing steps for users similar to collars  5  and  7  of the alternate embodiment  100  ( FIG. 6 ). None of the components of  FIG. 8  are drawn to any particular scale, and they can all be scaled to accommodate various desired poles and users. For example, standpipe  60  and couplings  20 ,  30 ,  40 , and  50  can be manufactured in various heights, thus presenting the opportunity for users of different heights to use the same apparatus with the change of one or more parts of the support tube assembly.  
         [0059]      FIG. 9  illustrates one of many possible alternatives to the present invention preferred embodiment. In assembly  21 , the two sections of pipe  22  and  23  coupled with coiled spring  24  simulate the spring action of spring steel pole  91  of the preferred embodiment. Sections  22  and  23  may be steel or composite, solid or tubular, and are inserted inside the ends of spring  24  with a press fit sufficient to preclude loosening during use. The size of sections  22  and  23  and spring  24 , and the depth of insertion of the sections into spring  24  are determined by the size of the intended users and the desired amount of pole flexure.  
         [0060]      FIGS. 10   a  and  10   b  illustrate one of many possible alternatives  300  to the present invention preferred embodiment  90 . In apparatus  300 , lower tube section  25 , pole  33 , pivot wheel  29 , cable  36 , piston  37 , stop  26 , and commonly understood compression spring  39  simulate the spring action of spring steel pole  91  of the preferred embodiment. Lower tube section  25  can be set in a concrete well in the ground or made part of a portable but stable base.  
         [0061]     In  FIGS. 10   a  and  10   b  compression spring  39  is fully extended, pushing piston  37  to its lowest position inside lower tube section  25 . The force exerted by spring  39  in its fully extended position is sufficient to raise pole  33  to its highest position, where tab  35  on bracket  28  butts against a similar tab (not shown) on bracket  32 . The extension of spring  39  raises pole  33  by means of cable  36  that is led through a center hole in piston  37  and captured with crimp  38 . As spring  39  pushes against stop  26  attached to the top of lower tube section  25 , piston  37  is forced down, away from stop  26 . The top end of cable  36  is attached to pulley  29  and causes pulley  29  to turn on axle  31  supported by brackets  28  attached to lower tube section  25 . Because brackets  32  are attached to pole  33  and to axle  31 , rotation of pulley  29  raises pole  33 . A user pulling on the distal end of pole  33 , the end farthest away from lower tube section  25 , compresses spring  39 , thus obtaining the same spring sensation experienced by a user of the spring steel pole of the preferred embodiment.  
         [0062]      FIG. 11  illustrates one of many possible alternatives to the present invention preferred embodiment. In apparatus  400  the lower tube section  42 , pole  43 , bushings  44  and  45 , and a commonly understood torsion spring  41  with first and second arms simulate the spring action of spring steel pole  91  of the preferred embodiment illustrated in  FIG. 1 . Lower tube section  42  can be set in a concrete well in the ground or made part of a portable but stable base. Bushing  45  is fixed inside lower tube section  42 , and the first arm of spring  41  is capable of rotation inside bushing  45 . Alternatively, the first arm of spring  41  is fixed to the center cavity of bushing  45 , and bushing  45  is capable of rotation inside lower tube section  42 . The second arm of spring  41  is fixed inside the center cavity of bushing  44 , which is fixed inside one end of pole  43 .  
         [0063]      FIG. 12  illustrates one of many possible alternatives to the present invention preferred embodiment. In apparatus  500 , lower tube section  42 , bushing  45 , and poles  46  and  47  simulate the spring action of spring steel pole  91  of the preferred embodiment illustrated in  FIG. 1 . Pole  46  is constructed of cylindrical spring steel identical or similar to the spring steel used for pole  91  of preferred embodiment  90 . Pole  46  is welded or otherwise attached to pole  47 , which is constructed of a material less expensive than spring steel. Alternatively, pole  46  can be constructed of flat spring steel. Lower tube section  42  can be set in a concrete well in the ground or made part of a portable but stable base. Bushing  45  is fixed inside lower tube section  42 , and pole  46  is capable of rotation inside bushing  45 . Alternatively, pole  46  is fixed to the center cavity of bushing  45 , and bushing  45  is capable of rotation inside lower tube section  42 .  
         [0064]      FIG. 13  illustrates one of many possible variations of the present invention preferred embodiment. Any of the ground tubes, ground support tubes, or lower tube sections described as part of the preferred embodiment or its alternatives can be set in concrete. Alternatively those components can be removeably held in a portable but stable base such as that illustrated in  FIG. 13 . Hollow watertight molded ABS plastic base  51  contains a central well  53  the interior of which has no communication with the interior of base  51 . Water filling base  51  through sealable port  54  will not enter central well  53 , which is capable of receiving any of the ground support tubes or lower tube sections described as part of the present invention preferred embodiment or its alternatives. Base  51  can be sized so that its weight, when filled with water, will provide stability sufficient for the size of the user of the present invention. Drain port  56  is a valve or cap through which water can be drained.  
         [0065]     Alternatively, base  51  can be manufactured using many materials other than ABS, and it can be manufactured with a port  54  large enough to accept sand, gravel, or other materials capable of providing the desired stability. Alternatively, for ease of transport and setup, base  51  can be manufactured as multiple interlocking sections, each having its own fill and drain ports. Alternatively, base  51  can be manufactured as a solid, thereby negating the need for filling. Flange  52 , integral with base  51 , has several slots through which stakes, lag screws, or bolts may be inserted for attachment of base  51  to various ground or floor materials.  
         [0066]     It will be apparent to those with ordinary skill in the relevant art having the benefit of this disclosure that the present invention provides an apparatus for recreational and fitness use. It is understood that the forms of the invention shown and described in the detailed description and the drawings are to be taken merely as presently preferred examples and that the invention is limited only by the language of the claims. The drawings and detailed description presented herein are not intended to limit the invention to the particular embodiment disclosed. While the present invention has been described in terms of one preferred embodiment and several alternatives thereof, it will be apparent to those skilled in the art that form and detail modifications can be made to those embodiments without departing from the spirit or scope of the invention.