in the following description , for purposes of explanation and not limitation , specific details are set forth in order to provide a thorough understanding of the present invention . however , it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details . in other instances , detailed descriptions of well - known methods and devices are omitted so as to not obscure the description of the present invention with unnecessary detail . fig1 is a perspective view of a single rider teeter - totter 10 in accordance with an embodiment of the present invention . a frame 12 comprises forward support member 14 and generally u - shaped rear support member 16 . the frame further comprises pivot support post 18 with pivot assembly 20 attached at the top thereof . longitudinal beam 22 is coupled to pivot assembly 20 . seat support member 24 is attached to beam 22 . the various components of frame 12 may be fabricated from tubular steel as is common for exercise and playground equipment , although other materials may be used if desired . seat 26 is attached to seat support member 24 . seat 26 may be constructed of a molded foam or plastic material . a handle bar 28 is attached to the upper portion of seat support member 24 . the weight of a rider in the seat 26 is counterbalanced by springs 32 . a pair of springs is used in parallel so that if one of the springs fails , the second spring will still provide half of the counterbalancing force to prevent the teeter - totter from falling uncontrollably . in the event of a spring failure , or if the spring resistance is not properly adjusted , or if the rider is simply overly exuberant , impact with the ground is cushioned by bumper 30 attached to seat support member 24 . furthermore , the design of generally u - shaped rear support member 16 ensures that the rider will not contact any of the frame members at the bottom limit of travel and also eliminates pinch points in the vicinity of the seat . fig2 illustrates the spring height adjustment mechanism , which sets the rest height of the seat and thereby also acts as a range of travel adjustment . this mechanism adjusts the lower attachment point of springs 32 and thereby adjusts the height of seat 26 off of the ground . yoke 34 is attached to forward support member 14 and carries adjustment screw 36 . the lower ends of springs 32 are attached with chain links 33 to follower 38 , which is threadably engaged on adjustment screw 36 and slides within guides 39 . knob 40 is used to manually rotate adjustment screw 36 , thereby raising or lowering follower 38 . a numerical indicator 41 may be provided to assist riders in setting the seat height at a desired level . guides 39 prevent twisting of the springs 32 as the vertical position of follower 38 is adjusted . this type of a lead screw adjustment mechanism provides virtually infinite adjustment within the travel of follower 38 on screw 36 and remains in a selected position without the need for any additional locking or detent mechanism . the chain links 33 constitute flexible couplings that communicate tensile forces , but not compressive forces . as the rider approaches the top of the range of movement , the springs become fully relaxed and the chain links allow for continued upward movement . the rider thus experiences a free - floating or weightless sensation at the top of the range of movement . fig3 is a detailed view of the counterbalance adjustment mechanism . adjustment screw 42 is suspended below beam 22 . the upper ends of springs 32 are attached to follower 44 , which is threadably engaged on adjustment screw 42 . knob 46 is used to manually rotate adjustment screw 42 , thereby moving follower 44 fore and aft in relation to beam 22 . when follower 44 is moved closer to pivot 20 , the effective resistance of springs 32 is reduced , which is desirable for use of the apparatus by a lighter rider . conversely , a heavier rider would turn knob 46 to move follower 44 further away from pivot 20 , thereby increasing the effective resistance of springs 32 . a numerical indicator may be provided on beam 22 as illustrated to assist riders in setting the effective resistance to a desired value . fig4 shows an optional elastic shroud 50 that surrounds the springs 32 . this protects children from having their fingers or other parts of their bodies pinched by the springs as they stretch and relax . fig5 shows an optional secondary counterbalance 52 . this may be an elastic cord that provides additional counterbalancing force in the event that one or both of the springs breaks . cord 52 is coupled in parallel with the springs 32 and may be threaded though the center of one of the springs if desired . cord 52 could also be inelastic to serve as a safety tether to stop the downward movement of the seat before it strikes the ground . fig6 shows an alternative counterbalance adjustment mechanism . here , longitudinal beam 22 ′ is notched with detents 65 along a portion of its length . springs 32 are attached to slider 60 , which rides along beam 22 ′ and is configured to be gripped by hand . a trigger 62 is pivotally attached to slider 60 and is biased towards an engaged position by spring 64 . squeezing trigger 62 releases detent lock 66 from engagement with detent 65 and allows slider 60 to be moved forward or rearward to a desired position . as in the previously described embodiment , a numerical indicator may be provided on beam 22 ′ as illustrated to assist riders in setting the effective resistance to a desired value . it will be recognized that the above - described invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the disclosure . thus , it is understood that the invention is not to be limited by the foregoing illustrative details , but rather is to be defined by the appended claims .
a safer , more user - friendly spring - balance single - rider teeter - totter includes manual adjustments for both the vertical position of the spring , which adjusts the rest height of the seat , and the horizontal position of the spring from the pivot , which adjusts the counterbalance resistance . a safety cover may be provided for the spring or other counterbalance mechanism .