US3480274A

US3480274A - Gymnastic amusement device

Info

Publication number: US3480274A
Application number: US525892A
Authority: US
Inventors: Robert Boggild; William L Dale
Original assignee: CROSSBOW Inc
Current assignee: CROSSBOW Inc
Priority date: 1966-02-08
Filing date: 1966-02-08
Publication date: 1969-11-25
Anticipated expiration: 1986-11-25
Also published as: DE1578521A1; GB1134661A; DE1578521B2; AU413286B1

Description

Ney. 2s, R969 R. BOGGILD ET AL l 3,480,274

GYMNAsTIc AMUSEMENT DEVICE Filed web. e. 196e 2 Sheets-Sheet' 2 United States Patent O U.S. Cl. 272-60 6 Claims ABSTRACT OF THE DISCLOSURE A gymnastic amusement device wherein a fiberglass pole is mounted in a socket, the fiberglass pole having spaced steps to permit a child to climb upon the pole, and the pole having damping means to minimize the whipping action of the pole.

This is a continuation-in-part of copending application Ser. No. 251,225, iiled Jan. 14, 1963 and now Patent No. 3,246,893.

This invention relates to a gymnastic device and is particularly directed to a device on which energetic children, and even aduts, can ind an unusual and entertaining form of exercise.

The invention relates to a resilient device which, in a sense, has that characteristic of a trampoline which many people find -to be so enjoyable, namely, the characteristic of receiving and storing energy imparted to it by a person and immediately returning that energy to the body of the person to move him about. More specifically, the invention comprises a resilient pole, iirmly anchored at its base, upon which a child can climb. The weight of the child, together with the energy which he imparts to the pole as he swings on it, will cause the pole to oscillate or gyrate carrying the child with it. The variety of movements is infinite, the variation being attained in part simply lby the distance which the child climbs up on the pole and, still further, by the degree and direction of force which the child applies to the pole. For example, a child can cling to the top of the pole and, perhaps with friends pushing, can swing in a plane in which the pole touches the ground at one side and swings through its uppermost position to a position in which it touches the ground on the diametrically opposite side of the pole. As another example, a child can grasp the end of the pole with his hands and bound in circles around the pole.

In the prior art, there are rigid poles or other devices which a person can climb, the devices being mounted on varying types of bases and being adapted to move about when the persons impart a force to them. Relatively co-mplex types of bases have been designed to provide support for such rigid poles, each base permitting or imparting some type of movement of its pole. In addition to the cost of manufacturing such complex structures, the prior devices lacked an ingredient to which may be attributed a large part of the enjoyment to be derived from the present invention, namely, the whipping action of a resilient pole. It is the very fact of the simplicity of the present'invention which gives it this universal type action and distinguishes it from the cumbersome, limited devices of the prior art. In short, the present invention provides greater enjoyment at less cost than prior structures.

It has been an objective of the invention to provide, as an amusement and exercising device, a pole anchored in the ground at its lower end and having a substantial length projecting above the ground, the pole being formed of longitudinally extending glass fibers bonded by a suitable resin. Resin bonded fiberglass has been found to be an ideal substance for this purpose for several reasons. It

ICC

has suflicient resilience and liexibility to be bent through an angle of greater than ninety degrees without destroying lits physical characteristics. Because of its low specific gravity, as compared to steel for example, it has a high damping characteristic so that, when bent to the ground and released, it will swing past its normal vertical positionthrohugh an angle of only about thirty degrees, thereby minlmizlng the possibility of striking a person.

It has been another objective of the invention to provide means for damping the natural vibration of the pole after it has been released from a bent condition. This feature of the invention not only further minimizes the possibility of the poles striking a person but also is desirable from a psychological standpoint of bringing the pole rapidly to a condition in which it is substantially still and ready for a person to grasp for further use.

These and other objectives of the invention will become more readily apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. l is an elevational view showing the invention in use,

FIG. 2 is an elevational View partly in section of segments of the pole and its mount,

FIG. 3 is an enlarged cross sectional view of the pole mount,

FIG. 4 is an enlarged cross sectional view of a pole step,

FIG. 5 is a cross sectional view taken along lines 5-5 of FIG. 2,

FIG. 6 is an elevational view illustrating an alternative embodiment of a damper, and

FIG. 7 is a cross sectional view taken along lines 7-7 of FIG. 6.

As illustrated in FIG. l, the invention comprises a fiberglass pole 10 which is mounted in a socket 11 by mounting means described in detail below, the socket being firmly supported in the ground or other surface. Two steps 12 are adjustably fixed on the pole to permit the pole to be climbed easily by a small child.

The pole is an elongated rod formed of longitudinally extending glass fibers bonded by a suitable resin and may be manufactured by any of several known processes. Rods of dimensions in approximately the range set forth below are capable of being bent through extreme angles exceeding forty-tive degrees and up to ninety degrees without permanent deformation. The rod may be one of a number of sizes ranging from an eight foot pole, three-fourths inch in diameter, to a twelve foot pole, one and one-fourth inch in diameter. It has been found that the three-fourths inch pole is satisfactory from the enjoyment standpoint for a sixty pound person and the one and one-fourth inch pole is satisfactory for a one hundred seventy-five pound person and that persons within twenty percent of the optimum weight can use the poles satisfactorily. Further, the pole is preferably of uniform diameter throughout its length, although it is possible to provide a pole which is tapered toward its free end. The tapered pole, however, has a dierent bending characteristic than the pole of uniform diameter, the different characteristic causing a person riding the pole to be pointed head down at the extremity of his excursion rather than lying at a substantially horizontal attitude as is shown in FIG. 1.

The mounting of the pole is of critical importance, particularly in relation to its life and freedom from severe localized stresses. The preferred form rof the mounting is illustrated in FIGS. 2 and 3. The pole has an integral mount 15 at its lower end, the integral mount being removably received in a tubular mounting socket 16. The mounting socket may be fixed in the floor structure of a gymnasium or may be buried in the ground as shown in the illustrated embodiment. When buried in the ground, the socket is preferably anchored in a hole 17 which is of hour-'glass configuration, the lower portion of the socket being secured by concrete indicated at 18, the middle portion being surrounded by a layer of gravel 19, and the upper portion being covered by concrete 20. The configuration of the hole takes maximum advantage of the resistance of the earth to displacement as the forces on the pole tend to pivot the socket in the earth.

The socket is about two and one-half feet to three feet long. At its upper end, a ring 22 is welded to the socket with the upper surface of the ring being ush with the end of the socket. The ring and socket are covered by a friction pad 23 of rubber or urethane. The friction pad provides the bearing surface upon which the pole and its integral mount rest and prevents the pole from rotating within the socket to any marked degree. This in turn assures a uniform stressing of the rod bearing members during the use of the pole. If'the pole were mitted to rotate in its mount, there might be a tendency for the pole to iiex repeatedly in a particular direction, thereby overstressing the rod supporting elements in a particular direction and decreasing the life of the elements.

The integral mount includes a mounting shell 25 having an integral retaining ring 26 welded at its lower end. A bottom plate 27 rests on the retaining ring 26 and an elastomeric pad 28 is positioned on the bottom plate. The pole rests on the elastomeric pad.

A retaining ring 29 is fixed on the lower end of the pole 10 to keep the pole from riding up and out of the shell. The retaining ring is press fitted into position and could be secured additionally with an epoxy resin adhesive.

A lower bushing 30 is disposed in the shell at its lower end and is engaged by the upper edge of the retaining ring 29. The lower bushing 30 is held in its position by a spacer tube 31 which extends from the lower bushing almost to the upper end of the shell. An upper bushing 32 is positioned adjacent the upper edge of the spacer tube and a collar 33 is welded to the top edge of the shell as at 34 to complete the mount structure. The collar 33 has a radially inwardly projecting ange 35 which overlies the upper bushing 32 and keeps that bushing from riding up and out of the shell. As can be seen from FIG. 3, the bushings 30 and 32 maintain the lower end of the pole spaced from the internal surface of the spacer 31, whereby that portion of the pole is free to flex without restriction as indicated by the broken lines 10a.

The

pads

23 and 28 and the bushings 30 and 32 are formed of an elastomeric material such as rubber or polyurethan-e. Polyurethane is preferred because of its toughness and resistance to wear.

The most critical of the mounting elements is the elastomeric upper bushing 32 because of the manner in which it is stressed during the use of the pole. A number of considerations are involved in its design. It must have a suiciently great vertical dimension to keep the unit pressure low, that is, the pounds per square inch of pressure in a generally radial direction. If the unit pressure imparted to it during the bending of the pole is too high, the elastomeric material will be compressed so greatly that it becomes hard and resists the movement of the pole as if it were concrete. Under these conditions, the pole will rupture in a very few cycles of operation. On the other hand, the bushing must be stift` enough to prevent the pole from engaging the metallic parts forming the mount, for this, too, would provide too great a resistance to the exure of the pole and cause its early rupture. Further, the bushing must be flexible enough so that it does not restrict the pole when it bends. While as stated above the bushing must have a sufficiently large vertical dimension to keep the pressure on it low, the length of the bushing must not be too great, for, in bending as shown in broken lines 10a in FIG. 3, the movement of the pole toward the wall of the shell will tend to overcompress the lower extremities of a long bushing until it compacts and becomes so hard as to cause the early rupture of the pole.

To achieve the ends required as set forth above, the bushing is formed of a high durometer elastomer (-90 durometer), is shaped as a buttress in cross section, and has two annular slots 38 formed in its outside surface. The slotting of the bushing provides space for the elastomer to ow as it is stressed, thereby avoiding the overcompacting of it which causes the rupture of the pole. The buttress configuration also provides the desired direction of flow of the elastomer particularly at the upper end of the bushing. There, the tapered surface prevents a bulging of the elastomer above the collar 33 which causes it to scui and reduces its useful life. By way of example, for a one inch diameter pole the bushing 32 is trapezoidal in cross section, the trapezoid having a height (radial dimension) of one-half inch, a seven-eighths inch smaller base, and a one and one-eighth inch larger base. The slots extend into the bushing about two-thirds the height of the trapezoid.

The outer surface of the pole is preferably covered along its length by a vinyl sheath or skin which is stretched and rglued to the pole. The skin minimizes the abrading of the fibers from which the pole is formed during the operation of the invention and, perhaps more importantly, it keeps loose fibers from pricking the hands of the user.

Two steps 12 are preferably secured to the pole a distance of approximately two feet and four feet respectively from the ground level and the steps are adjustably mounted. The steps not only provide a convenient means for a child to climb to the top of the pole but also provide a place for the child to stand during the use of the pole. For this reason, it is particularly important to provide for the adjustment of the position of at least the uppermost step along the length of the pole so that the child can adjust the step to that position on the pole which is best suited for his height and weight.

As shown in FIG. 4, the steps include an integral plate 40 and downwardly depending bushing 41. The bushing is externally threaded as at 42 to receive an internally threaded clamping nut 43. The nut has a pair of diametrically opposed lugs 44 projecting radially from it to provide the leverage required for tightening the step on the pole. The step has a central hole 45 through which the pole passes, the diameter of the hole 45 being substantially greater than the diameter of the pole. An elastomer sleeve 46, preferably soft rubber, is disposed in the hole 45 between the step and the pole and it is the compressing or packing of the sleeve 46 into the hole 45 which provides a frictional grip of the step to the pole. To contain the sleeve 46 within the hole 45, the step has an inwardly projecting lip 47 which overhangs the sleeve 46. The lower end of the sleeve is engaged by a conical Teflon Washer 48 which rests on an inwardly projecting lip 49 integral with the nut 43. The Tellon washer permits the nut to be rotated with respect tothe sleeve without twisting the sleeve on the pole and, therefore, the force applied to the sleeve as the nut is tightened on the depending bushing is substantially entirely in an axial direction. The leverage permitted by the lugs 44 enables even a small child to tighten the step to the pole to the extent required to support the weight of the child.

The pole optionally may be provided with-damping means. The damping means is actually not truly necessary for the enjoyment of the use of the pole or for safety in the operation of the pole. Even if the pole is bent until its tip touches the ground and is released, the top of the pole will only swing past center through an angle of less than thirty degrees and it is therefore unlikely that the pole would ever strike and injure a person. However, upon being released, the pole will tend to vibrate at its natural frequency for a number of seconds up to a half minute during which play on the pole must cease. The objective of this feature of the invention is to reduce the speed at which the pole swings upon being released by a factor of two and thereby reduce the impact (which is proportional to the square of the speed by a factor of four). In one form of the invention, damping is effected by placing a weight of approximately half the weight of the pole (three to six pounds) at the top of the pole. Not only does the weight reduce the speed of the pole but it also moves the center of gravity up the pole where it is well above the point of impact on a person standing on the ground. Since the center of gravity is above any possible point of impact, the impact is less abrupt than it would be if the point of impact were coincident with the center of gravity.

As shown in FIGS. 2 and 5, the damper comprises a sleeve 55 which is secured to the upper end 56 of the pole by a screw 57 passing through a hole 58 in the pole and threaded as at 59 in the sleeve. A substantial portion of the sleeve extends above the pole and is liilled with lead 60 or other heavy metal. Additionally, the damper may be covered by a polyethylene foam cap 61 having four equiangularly spaced wings `62 projecting radially outwardly from a hub 64. The hub has a central hole 65 into which the damper projects when the cap is iitted in place. The winged cap does not have to be secured to the damper for it does not have suiiicient mass to be flung from the pole during the vibration of the pole The Winged cap does not appear to have any marked eiiect on the speed of the iirst excursion of the pole when it is released but the wind resistance which it imparts to the pole provides a substantial reduction in the number of excursions which the pole takes before coming to rest.

An alternative form of the damper is illustrated in FIGS. 6 and 7. In this embodiment, damping is eiected by applying a visco-elastic material to the lower end of the pole, the -materal extending from ground level to approximately two feet above the ground. This portion of the length of the pole is most greatly stressed during liexure of the pole and consequently stores the greater amount of potential energy when the pole is bent. The Visco-elastic material has the quality of high energy absorption per unit volume. That is to say, when the material is stressed and deformed, substantially all of the energy is absonbed by the material and lost. When this material is bonded to the lower portion of the pole and the pole is iiexed, a substantial portion of the energy of the pole is absorbed in the material and is therefore unavailable to whip the pole.

In the illustrated form of the invention, the material indicated at 66 is in the form of sheets 67 which are wrapped about the pole and each other with their ends butting and bonded to the pole and to each other. A onefourth inch total thickness of material around the base of the pole has been found to provide as substantially good results as the damper iixed to the free end of the pole as described above.

In the operation of the pole, the pole is mounted with its lower end in the socket 16 and the steps are adjusted to suit the desires of the user according to his weight and height. As indicated above, the varieties of gyrations permitted by the pole are almost limitless. For example, a child can stand on the uppermost step and simply sway back and forth. He can climb out to the end of the pole and increase the arc through which he sways. By hanging onto the end of the pole, he can bound in great leaps around the center of the pole or he can leap substantially diametrically back and forth.

As indicated above, it is important to this flexing of the pole that the pole be mounted at its base to provide a simple beam support for the pole as contrasted to a cantilever support. The spaced elastomeric bushings 30 and 32 at the lower end of the pole space the pole from the shell and permit that portion of the pole between the bushings to flex substantially without restraint. As a consequence of the mounting, when the force is applied to the pole during its use so as to bend it all the Way to the ground, the pole at the base is curved gradually as is permitted by the two position, flexible mount. Thus, the mounting eliminates the localizing of the stress at the juncture between the pole and the socket in which it is mounted.

We claim: 1. An amusement device comprising, an elongated resilient flexible pole adapted ot be vertically mounted with its lower end disposed in a socket,

said pole having suiiicient rigidity to support a small child and having suiiicient resiliency to permit the pole to bend throughout substantially its entire length through an angle of at least 45 without permanent deformation, and p a damping means fixed to said pole for minimizing the whipping of the pole after it has been bent and released, said damping means being secured to one end portion of said pole and movable therewith, said damping means extending from the end portion a distance of no more than approximately one-fourth the length of the pole, whereby at least three-fourths of the length of the pole is free to be grasped by the user.

2. An amusement device according to claim 1 in which said damping means comprises a weight attached to the free end of said pole.

3. An amusement device according to claim 2 in which said weight is equal to approximately one-half the weight of said pole.

4. An amusement device according to claim 1 in which said damping means comprises a sleeve of Visco-elastic material bonded to the surface of the lower end portion of said pole immediately above said socket.

5. An amusement device according to claim 4 in which said Visco-elastic material is approximately one-fourth inch thick.

6. An amusement device according to claim 1 in which said damping means comprises a substantially rigid lightweight element mounted in one end of said pole, said element having a plurality of virtically extending vanes projecting laterally from said element.

References Cited UNITED STATES PATENTS 602,517 4/1898 McFadden 27278v 1,047,212 12/1912 Hamilton 272-57 1,141,292 6/1915 Weise 272-25 1,276,959 8/ 1918 Riebe. 2,198,537 4/1940 Jones et al 272-60 2,725,233 11/ 1955 Werner. 2,887,319 5/1959 Lay. 2,906,531 9/ 1959 Merickel et al. 2,949,298 8/ 1960 Speelman 272-1 3,216,727 11/ 1965 Hunter 273-106-.5 2,709,079 5/1955 Bubb et al. 272-65 3,246,893 4/ 1966 Boggild et al 272-65 X 3,268,223 8( 1966 Woodsum 272-57 X ANTON O. OECHSLE, Primary Examiner ARNOLD W. KRAMER, Assistant Examiner U.S. Cl. X.R