Abstract:
A playground device, in the nature of a teeter-totter, includes first and second spaced base members. An arcuate rail is coupled to the base members in an upright arc. An arcuate member surrounds at least a portion of the rail and is mounted for to-and-fro movement relative to the rail. User platforms or other user-friendly features are mounted on the tube. A biasing mechanism coacts between the member and the rail to bias the member toward a predetermined preferably central position on the rail, while allowing the tube to move to-and-fro on the rail.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to novel playground equipment, and more particularly, to an apparatus that can be used by one or more people and the function of which is somewhat comparable to the conventional teeter-totter.  
       BACKGROUND OF THE INVENTION  
       [0002]     A conventional teeter-totter has been used on playgrounds for many years. Recently, there has been concern about the safety of the teeter-totter and thus, its use has decreased significantly. There has, therefore, been for some time, a need for a safe substitute for the conventional teeter-totter.  
       SUMMARY OF THE INVENTION  
       [0003]     The present invention therefore provides a playground device comprising first and second base members. An arcuate rail is coupled to the base members. An arcuate member, preferably a hollow tube, surrounds at least a portion of the rail and is mounted for to-and-fro movement relative to the arcuate rail. User platforms may be mounted at each end of the member. Finally, a biasing means coacts between the member and the rail to bias the member toward a predetermined, preferably central, position on the rail, while allowing the member to move to-and-fro on the rail. Preferably, the arcuate rail and hollow tube are segments of a circle. The rail is mounted in an upright position so as to extend first in an upwardly extending arc, and then in a downwardly extending arc. The rail thus has an uppermost, central portion that coincides with the preferred central position toward which the biasing means urges the tube.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]     The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
         [0005]      FIG. 1  is an isometric view of the playground device of the present invention viewed from the upper right;  
         [0006]      FIG. 2  is an isometric view of the playground device viewed from the lower right;  
         [0007]      FIG. 3  is a side elevation view of the playground device;  
         [0008]      FIG. 4  is an enlarged side elevation view of the left portion of the device in partial cross section showing the hollow tube biased toward the predetermined position;  
         [0009]      FIG. 5  is a view similar to  FIG. 4 , showing the hollow tube being urged in one direction against the biasing means;  
         [0010]      FIG. 6  is a view similar to  FIG. 5 , showing the hollow tube being further biased toward a position and urged against a stop mechanism;  
         [0011]      FIG. 7  is an exploded isometric view of the truck mechanism affixed to the hollow tube that rides on the rail;  
         [0012]      FIG. 8  is an enlarged isometric view of the truck mechanism; and  
         [0013]      FIG. 9  is an exploded isometric view of the truck mechanism. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0014]     Referring to  FIGS. 1, 2 , and  3 , the playground device  20  of the present invention comprises a pair of base members  22  and  24 . The base members are held in a horizontally spaced location by a pair of temporary spreader bars  26  and  28 , the ends of which are respectively temporarily affixed to opposite base members  22  and  24 . The spreader bars  26  and  28  stabilize the horizontal position of the base members during installation. Each of the base members  22  and  24  carries an anchor  30  and  32 , respectively. The anchors  30  and  32  are affixed to the bottom portion of the base members by any conventional fastening means. When installed, the base members lie on the surface of the playground on which the device is installed. The anchors are normally embedded in a concrete footing.  
         [0015]     A pair of support arms  36  and  38  are respectively mounted on the base members  22  and  24 . The support arms  36  and  38  extend upwardly and arcuately. As will be explained in more detail later, a rail, which preferably comprises a segment of a circle, is attached to the upper end of the arms  36  and  38 . The rail carries a hollow tube member  40 , which is positioned for to-and-fro movement relative to the rail and the support arms  36  and  38 . This to-and-fro movement is signified by the arrow  42  in the figures. As shown in  FIG. 3 , the hollow tube  40  can move in a leftward and downward arc to a position  40   a  shown in dotted outline adjacent base member  22  and can move in a rightward and downward direction to a position  40   b  shown in dotted outline adjacent base member  24 . The hollow tube  40  is biased toward a center position indicated by arrow  42  by a biasing mechanism described in more detail below.  
         [0016]     Still referring to  FIGS. 1-3 , user seats  44  are mounted on the outer portion of the hollow tube  40  adjacent each of the ends. Second user seats  46  are mounted on the inner portion of the hollow tube  40  above the location of seats  44 . In addition, handrails  48  and  50  are mounted on each side of the center position of the tube  40 . Children can thus seat themselves on seats  44  and push off the base members with their feet to enjoy an up and down riding motion on the arcuate tube providing a sensation similar to that of a conventional teeter-totter. The playground device of the present invention, however, does not exhibit any of the negative aspects of the teeter-totter in that this device is biased to a center position. Thus, if one of the children should, for example, exit seat  44 , the device will not suddenly move in the opposite direction, but instead will be restrained by the biasing mechanism and by a second stop mechanism described in more detail below. Similarly, the handrails can be grasped by children using the device to rock it back and forth as intended.  
         [0017]     Referring now to  FIG. 4 , an enlarged view of the left half of the playground device  20  is illustrated in partial cross section. The left base member  22  is shown with only a portion of the anchor  30  extending below it. The support arm  36  extends upwardly from the base member in a circular arc. The right half of the device is the mirror image of the left half shown in  FIG. 4 . About 20°-30° above the base member  22 , the rail  60  is attached to the upper terminus of the support arm  36 . This attachment is via conventional means. The rail  60  has a diameter less than that of the support arm  36 , forming a shoulder  62  on the upper edge of the support arm  36 . A coil stop spring  64  surrounding the rail has its lower end positioned against the shoulder  62 . The function of the stop spring will be described in more detail below.  
         [0018]     The left half of the hollow tube  40  comprises two segments  66  and  68 . The two segments  66  and  68  are joined by a truck mechanism  70 , described in more detail below. The truck mechanism secures the segments  66  and  68  together and also carries a set of wheels that ride on the rail so as to allow relatively frictionless, reciprocating movement of the truck and thus, the tubular member  40  relative to the rail  60 . The upper end of the second segment  68  of the tubular member is joined by another truck  72  to the upper segment  74  of the right half of the tubular member  40 .  
         [0019]     The uppermost (preferably central) portion  80  of the rail  60  is shown bisected by a vertical plane  82 . The vertical plane  82  bisects the playground device into its left and right halves. The tubular member is urged or biased to this position by a biasing mechanism that includes a coil spring  84  that abuts the left side of central truck  72  and abuts a stop washer  86 , positioned on the rail outwardly from the plane  82 . The stop washer is fixed at its location to the rail  60  via a stop pin  88 . The stop pin  88  is inserted through a diametric bore in the rail  60 . Additional bores  90  and  92  are provided so that the position of the washer  86  can be adjusted further away from the vertical plane  82  to accommodate different length springs and/or to accommodate pre-tensioning of the spring  84 . A similar biasing spring  94  is positioned in the right half of the playground device in mirror image to the springs described in this figure.  
         [0020]     As shown in  FIG. 4 , the tubular member  40  is shown at its at rest position biased so that the central portion of the tube and central truck  72  lie along the vertical plane  82 . Referring now to  FIG. 5 , the tubular member  40  is shown urged in a leftward and downward direction indicated by arrow  100 . As this occurs, the center truck  72  moves away from the vertical plane  82  and compresses the spring  84  against the stop washer  86 . The force to move the tubular member  40  in the direction of arrow  100  is provided by the co-action of either one person sitting on the seat  44 , for example, or by persons sitting on both seats  44  on the left and right-hand sides of the device, with the person on the right-hand side providing an upward thrust, for example, with his legs against the right-hand base member  24 . This allows the tubular member to compress the biasing spring  84 . As it is compressed, it slows and stops the leftward movement of the tubular member  40 . The spring  84  then releases its energy and moves the tubular member  40  back to its centered position. If, for example, the user in the left-hand seat  44  thrusts downwardly with his legs, the tubular member will pass the center point and compress biasing spring  94  on the right-hand side of the device  20 . As noted above, the right-hand side of the device functions in mirror image to the left-hand side shown in  FIGS. 4, 5 , and  6 . Thus, the centering/biasing spring  94  and a stop spring on the right-hand mirror image half of the device work in mirror image to the springs on the left side of the device as well.  
         [0021]     If, for example, a person sitting on the right-hand seat  44  suddenly exits the device leaving a person on the left-hand seat  44 , the tubular member would move to the left as shown in  FIG. 5 . The tubular member would tend to continue in the direction of arrow  100  because a person remains on the left-hand seat. As that occurs, the tubular member would move further downwardly, as shown in  FIG. 6 , at which point the truck  70 , joining segments  66  and  68 , would engage the stop spring  64  seated against the shoulder  62  on the support arm  36 . The spring  64  has a spring constant that will bring the tubular member to a rest before the bottom end  102  of segment  66  contacts the base member  22 . Further safety is designed into the device in that the bottom end  102  of the device  20  of the segment  66  is designed so that the space between the bottom end  102  and the base  22  is greater than any body part of the typical child using the device, thus preventing any compression injuries between the bottom end  102  and the base  22 .  
         [0022]     The biasing mechanism and the stop springs have been described in terms of mechanical coil springs. However, any physical device that is capable of performing the same function may be used. For example, elastic bands or compression devices may be substituted for the biasing springs and stop springs. Other equivalent devices, such as gas charged cylinders, may also be used.  
         [0023]     Turning now to  FIG. 7 , the central truck  72  joining tube segments  68  and  74  is illustrated. The tube segment  74  is shown in an unassembled condition slightly spaced from the truck  72 . The truck  72  serves the dual purpose of affixing the ends of tube segments  68  and  74  together and provides support for a plurality of wheels that ride on the center rail.  
         [0024]     Referring to  FIGS. 7, 8 , and  9 , the generally annular body of the truck  72  has left and right halves  110  and  112 . A central opening or bore  114  is provided through which the rail  60  extends. The two halves  110  and  112  are held together by conventional fasteners  116  extending through bores that are parallel but spaced outwardly from the central bore  114 . Preferably, four fasteners  116  spaced at 90° locations about the central bore  114  are provided. The interior of the halves  110  and  112  are provided with recesses that carry four wheels  120  spaced at 90° locations in the interior of the truck. The axles are positioned in mating recesses in the halves  110  and  112  so that when the halves are joined, the axles are fixed in place. The axles are oriented so that the wheels rotate in a plane oriented in the longitudinal direction of the rail. The wheels are positioned such that they extend slightly into the bore  114 . Opposing wheels are spaced at a distance approximately equal or slightly larger than the diameter of the rail  60  so that the wheels will rotate on the side of the rail and the trucks will smoothly carry the tube in a to-and-fro motion along the rail.  
         [0025]     The truck  72  also carries four projections  130  that extend radially outwardly from the outer annular surface of the truck  72 . The projections are also annular in configuration with one-half of each annulus residing on truck half  110  and the other half residing on truck half  112 . When the truck halves  110  and  112  are joined together, the annular projections are completed and extend outwardly from the truck  72 . Positioned in a cavity within the truck halves  110  and  112 , below the central bore of the annular projections  130 , are nuts  132 . The nuts are aligned with the axis of the bores of the annular projections  130 .  
         [0026]     Referring back to  FIG. 7 , the ends of the tubular segments  68  and  74 , when joined together, have annular depressions  140 , half of which are formed on opposing segment ends of tubes  68  and  74 . The annular depressions are spaced circumferentially at 90° from each on the tubes  68  and  70 . When the tubes are abutted, an annular depression is formed with a central opening. The central opening is sized to fit around and receive the annular projections  130  on the truck. To join the segments together and fasten them to the trucks, grommets  142  having a downwardly extending lip  144  are sized to fit into the depressions  140 . As shown, four annular depressions  140  are positioned around the tube segments  68  and  74 . The grommets  142  are inserted into the annular depressions  140  and fasteners  146  are inserted through the bore in the center of the grommets  142 . These fasteners  146  are threaded into the nuts  132  embedded in the truck to thus securely fasten the grommet  142  in the annular depression  140 , thus performing the dual function of securing the segments  68  and  74  to the truck  72  and securing the segments  68  and  74  to each other.  
         [0027]     While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.