US3120955A

US3120955A - Playground climbing apparatus

Info

Publication number: US3120955A
Application number: US101398A
Authority: US
Inventors: Edward T Carlin
Original assignee: Universal Manufacturing Co
Current assignee: Universal Manufacturing Co
Priority date: 1961-04-07
Filing date: 1961-04-07
Publication date: 1964-02-11
Anticipated expiration: 1981-02-11

Description

Feb. 11, 1964 E. 'r. CARLIN 3,120,955 PLAYGROUND CLIMBING APPARATUS Filed April 7, 1961 4 Shets-Sheet 1 INVENTOR Edward T Carlin ATTORNEYS Feb. 11, 1964 E. T. CARLIN 3,120,955

' PLAYGROUND CLIMBING APPARATUS Filed April 7, 1961 4 Sheets-Sheet 2 I'NVENTOR EdwurdTCqrlin ATTORNEYS 1964 E. T. CARLIN 3,120,955

PLAYGROUND CLIMBING APPARATUS Filed April 7, 1961 4 Sheets-Sheet 5 INVENTOR j- .7 Q EdwordTCorlin BY %w/% %zz.

ATTORNEYS Feb. 11, 1 964 E. T. CARLIN 3,120,955

PLAYGROUND CLIMBING APPARATUS Filed April '7 1961 4 Sheets-Sheet 4 I? if uw/m INVENTOR Edward T Carlin BY M ATTORNEYS United States Patent 3,120,955 PLAYGROUND tILIMBING APPARATUS Edward T. Carlin, Shreveport, La., assignor to Universal Manufacturing (30., Inc, Bossier City, La., a corpcration of Louisiana Filed Apr. 7, 1961, Ser. No. 101,398 17 Claims. (Cl. 272-60) The present invention relates to play equipment for children and more particularly to an improved apparatus upon which children can climb, swing, hang or the like, thus obtaining healthy enjoyable exercise while at play.

Many kinds of playground type equipment and exercise apparatus devised for the amusement and physical development of children through climbing, hanging, swinging or the like have heretofore been provided. Such devices, to be practical and serviceable, must be structurally stable and of strong and rugged construction. To accomplish this result, the component parts used in the past in making playground equipment have been made up of large numbers of elements, are heavy and bulky, require large cartons for shipping and storage by retailers, require considerable assembly time and effort and, because of the high shipping and storage costs, in some cases equalling or exceeding the original cost of production, the ultimate consumer cost is made unduly high.

Such prior playground type equipment has not found a ready market for use in the yards of homes because its bulk and Weight militate against convenient packaging for over-the-counter sale and because of the tedious A and difiicult assembling of the component parts requiring special assembly tools or skill not possessed by many parents.

Accordingly, it is a primary object of this invention to provide an improved safe, lightweight, structurally stable climbing apparatus adapted for home and school use comprising relatively few component parts, requiring little packing or storage space when dismantled, and assuring quick and simple assembly even by unskilled persons.

Another object of this invention is to provide a climbing apparatus with a minimum number of assembled parts which are simple and economical to manufacture and which, when assembled, are mutually reinforcing to provide a structurally integrated apparatus that can survive the abuse normally incurred in use.

A still further object of the instant invention is to provide a climbing apparatus capable of use by one or more persons which assures maximum physical exercise yet, due to its unique construction, is extremely safe.

Another object of the instant invention resides in providing a playground or backyard piece of equipment comprised of a minimum number of elements that may be compactly packaged in knocked-down form for over-th counter sale and readily assembled by the ultimate purchaser of minimum mechanical skill using conventional tools commonly found in the average home.

Other objects and advantages of the invention will become more apparent by reference to the appended claims and from the following description and drawings wherein:

FIGURE 1 is a perspective view of the apparatus of the present invention in its finally assembled form;

FIGURE 2 is a perspective view of one of the side subassemblies of the apparatus of FIGURE 1;

FIGURE 3 is a side elevational view of the climbing apparatus of the instant invention;

FIGURE 4 is an end view of the climbing apparatus of the instant invention;

FIGURE 5 is a top plan view of the climbing apparatus of the instant invention;

FIGURE 6 is a partially sectional side view of a U- 2 shaped reinforcing member used in the climbing apparatus of the instant invention;

FIGURE 7 is a partially sectional side view of a reinforcing connecting member used in the climbing apparatus of the instant invention;

FIGURE 8 is a partially sectional side view of a typical connection used in the climbing apparatus of the instant invention, taken substantially along the line 88 of FIGURE 3; and

FIGURE 9 is a perspective view of a modification of the climbing apparatus of the present invention.

Referring in detail to the drawings wherein like reference numerals indicate like parts, therein shown in FIGURE 1 is the climbing apparatus 20 of the instant invention.

Climbing apparatus 20 is comprised of two identical structural

side frame subassemblies

22 and 24, one of which is shown in FIGURE 2 and will be described in detail. Subassemblies 22 and 24 are connected together by tubular reinforcing connecting members to form a unitary structurmly sound reinforced climbing apparatus in a manner to become more apparent from the following description.

Returning to FIGURE 2, subassembly 24 is comprised of two spaced angularly related bent major tubular ground

engaging support legs

26 and 28 and two spaced bent minor tubular ground

engaging support legs

30 and 32. The straight lower portions of major

tubular support legs

26 and 28 and minor tubular support legs 34] and 32 are disposed parallel to one another and the upper bent angularly extending

portions

34 and 36 of minor support legs as and 32 respectively extend in a substantially vertical direction toward

major support legs

26 and 28 respectively and are connected thereto by bolt and

nut assemblies

38 and 40 respectively. The major and minor support legs are additionally connected together by three spaced horizontal reinforcing tubular members 46, 4S and Eli. Long horizontal reinforcing tubular member 46 is connected to major and

minor support legs

26 and 30 by bolt and

nut assemblies

52 and 54 respectively and to major and minor support legs 23 and 32 respectively by bolt and

nut assemblies

56 and 58. Medium length horizontal reinforcing tubular member 48 is connected to major and

minor support legs

26 and 30 by bolt and nut assemblies 6%} and 62 respectively and to major and

minor support legs

28 and 32 respectively by bolt and

nut assemblies

64 and 66.

Short horizontal reinforcing tubular member 50 is connected to major and

minor support legs

26 and 30 at their juncture by bolt and nut assembly 38 and to major and minor support legs 23 and 32 at their juncture by bolt and nut assembly 4% As is best shown in FIGURES 1 and 3, in reinforced interconnected position major and minor support legs 2s and 3G converge toward major and minor support legs 28 and .32, and reinforcing

tubular members

46, 48 and 56 are horizontally dispose-d relative to the ground engaging ends of each of the major and minor support legs such that subassembly 24 forms an A-frame type reinforced structure.

Referring again to FIGURE 2, the upper ends of bent

major support legs

26 and 28, which extend along beyond the tops of minor support legs 3%) and 32, are connected together at their first and second bends by spaced horizontal tubular reinforcing members 74- and 76 by bolt and nut assemblies '78,

8t

32 and 84 respectively. The side frame subassemblies 22 and 24 thus each comprise

horizontal members

46, 48, 5d, 74 and 76 and

upright members

26, 23, 3t and 32 rigidly interconnected as described above and shown in FIGURE 2.

In the final assembly as shown in FIGURES 1 and 3,

horizontal reinforcing tubular members 50, '74 and 76 of each of the

subassemblies

22 and 24 are interconnected at their opposite ends by identical U-shaped tubular reinforcing members ?tl, best seen in FEGURE 6. In the actual processof assembly of this unit, members W are not placed in position on the

subassernblies

22 and 24 until after the

subassernblies

22 and 24 have been placed in upright positions and interconnected, as will be described presently. The hollow

parallel extending ends

92 and 94 of each tubular U-shaped member 9t! are of slightly larger internal diameter than the external diameter of

ends

96 and 98 of reinforcing members 5t and 76 and slide over the ends 96 and 93 respectively. By this construction U-shaped members 9% connect space the associated ends of tubular reinforcing members on and 7e apart the same distance as is determined for the central portions thereof by the boltand nut assemblies 38, alil, S2 and 8a! which connect reinforcing members 50 and '76 to

major support legs

26 and 28. In final assembly, the U-shaped members 99 are maintained in their assembled positions and. provide further structural integrity between horizontal reinforcing members 5% and '74 by bolts 7 rigidly connecting the ends of the horizontal reinforcing mernbers 74 to the central portion of each associated U-shaped support member 9t).

From the foregoing description it will be apparent to one skilled in the art that the

subassemblies

22 and 24, above described and shown in FIGURE 2, are of structurally integral reinforced construction wherein each of the members interacts to provide a simple rigid structure which is easily assembled by the average parent by simply bolting each horizontal reinforcing member to the outside of an appropriate support leg through the through bores provided in each of the members.

It will further be apparent that cantilever extending end portions of the horizontal reinforcing members 5-9, 74 and 76 are reinforced in final assembly by the Ushaped reinforcing members 90 and that the bottom portion of the 'subassembly is reinforced by virtue of the fact that two major and minor support legs are provided.

Further, it will be seen that forces applied to the top portion of the subassembly are divided between major and minor support legs 26 and 3tlat a critical force transfer point afforded by bolt 38. This connection will be fully explained later.

Referring now to FIGURES l, 3, 4 and 5, subassernbly 24, once assembled, is-connected to identical subassembly 22. To this end the top portions 1% and 1% of tubular major support legs 25' and 23 of subassembly 24 are connected tothe corresponding top portions'ltltl' and 192 of tubular major support legs 26 and 23' of subassembly 22. by tubular U=shaped reinforcing connecting members 194 and ltlti-respectively.

The legs 198 and 11d of each U-shaped member N4 and 106 diverge slightly (see FIGURES 4 and 5) from the final assembly.

To further fix the subassemblies in the position just .nut. assemblies 97 and 97' respectively to thereby interconnect, reinforce, and properly space the subassernblies Hand 24. V V

The

subassembiies

22 and 24 are further reinforced and fixed in position by identical tubular reinforcing connecting units 126 and 326 at approximately their median points. Each reinforcing unit P6 and 126, best seen in FIGURES 1 and 4, comprises a horizontal tubular reinforcing part 128 having downwardly bent crimped ends forming flanges 13%? and 132 and a tubular reinforcing part 134 having a horizontally extending portion 136 of approximately /3 the length of reinforcing part 128 and diverging leg portions 138 and 149. Slidably received on the terminal ends of diverging leg portions 133 and Mil of reinforcing part 134 are bent tubular reinforcing extensions 142 and 14-4, each having a short bent portion 146 and an elongated straight portion 1 5. The tubular extensions are secured at their bent end portions 146 to the respective diverging leg portions 133 and 14% by bolt and nut assemblies 151. The horizontal portion 136 of reinforcing part 134 is welded to the central portion of reinforcing part 128 preferably along substantially the entire length of their contacting surfaces to form the rigid reinforcing connecting unit 126.

Reinforcing connecting unit 126 is reinforcingly connected between

subassemblies

24 and 22 intermediate their length in the following manner. The depending crirnped ends 121i and 132 of part 128 are bolted to the

subassemblies

22 and 24 by previously mentioned bolt and nut assemblies 33 and corresponding bolt and nut assemblies 33 and the reinforcing

extensions

142 and 144 of reinforcing part 134 are bolted to the major supporting legs of the respective subassernblies 24 and 22 at their bent and intermediate their straight portions 148 by previously men tioned bolt and

nut assemblies

60 and 52 respectively and corresponding bolt and nut assemblies 60' and $2 respectively. Also each reinforcing

extension

142 and 144 is bolted adjacent the terminal end of its straight portion to the respective major support legs adjacent their ground engaging ends by bolt and nut assemblies 252 and 152% Reinforcing unit 126* is similarly connected to subassernlies 24- and 22 by bolt and nut assemblies 64, 64', til and 449'.

it should be noted that each of the bolt connections of i the parts of the subassernbly are easily made. For example, in reference to FIGURE 8, bolt 33 is easily inserted successively through aligned bores in horizontal reinforcing member 50, major support leg 26 and the bent end 3 of minor support leg 3t and the crimped end flange 13b of part. T28 of reinforcing connecting mem-' ber 126 and the associated nut then attached when these members are in their proper relative positions to rigidly fix these members together.

The subassernblies' having been described alone and in their connected positions, the manner in which the components interact to form a new and better structurally reinforced climbing apparatus will now be explained.

The climbing apparatus of the instant invention, as before mentioned, is easily assembled in that each of the connections-is a bolt connection and/ or merely requires the interfitting of hollow tubes over a rod.

The climbing apparatus of the instant invention is safe in that the only protruding ends upon which a child might possibly fall and be out are the ends of horizontal reinforcingrnembers. E6, 46', 48 and 43'. To eliminate this possibility, these ends are covered by identical resilient snugly fitting protective caps 15%, preferably formed of rubber or plastic and having a smooth exterior surface. All of the other exposed ends of the subassernbly components are closed by the U-shaped members 1%, 1%, 124' and 12,4.

The clnnbing apparatus of the instant invention is structurally stable. The

subassemblies

24 and 22 extend inwardly toward each other at their tops and are connected together by reinforcing connecting members to form an elongated pyramid-like structure. An overturning moment about an axis through the longitudinal centerline of the climbing apparatns'must be of maximum magnitude, greater than that which would be exerted by the weight of even several children climbing upon the apparatus simultaneously, to overturn the climbing apparatus as all forces about that axis are applied within the confines of the structure. For example, upon climbing up the side of the climbing apparatus by stepping from one horizontal reinforcing member to another of subassembly 24, a childs weight will be transferred directly from the horizontal members to the major and minor support legs of subassembly 24 and the overturning moment caused by such weight will be transferred through U-shaped reinforcing connecting

members

104 and 106 as a direct force to the major and minor support legs of subassembly 22. The vertical component of the childs weight will pass between the points at which the legs of subassembly 24 engage the ground and the points at which the legs of subassembly 22 engage the ground and thus will exert a stabilizing moment counteracting any overturning moment which the child might exert on the apparatus 20 by throwing his weight laterally while holding on to the apparatus. Due to the tubular U-shaped configuration of U-shaped reinforcing connecting

members

104 and 166 and the manner in which they fit into the hollow ends of the major support legs, the force transferred through these members will easily be absorbed and transferred without bending them.

Also, the overturning moments caused by swinging on the U-shaped reinforcing

connector members

104, 106 and 124 of the climbing apparatus are about an axis through the transverse centerline of the climbing apparatus. Due to the outwardly extending of the major and minor support legs along the longitudinal axis of the climbing apparatus, a downward force applied to U-shaped member 124, for example, by a childs swinging or climbing on it, acts through a very short overturning moment arm which is resisted by the entire weight of the climbing apparatus acting through a long resisting moment arm.

Further, the major and minor support legs will not buckle or sway because of the application of such a force because reinforcing connecting

members

104, 106, 124 and 126 cooperate between the support legs of the subassembly to rigidly reinforce them with respect to each other.

Also, each subassembly is structurally stable in that substantially equally spaced horizontal reinforcing members extend between the support legs from top to bottom of the structure; bending of the top cantilever extending horizontal reinforcing

members

50, 74 and 76 is effectively resisted by the force distributing effect of U-shaped members Ml; bending of the lower reinforcing

members

46 and 48 is resisted by supporting them from both major and m'mor support legs; and bending of the major support legs is resisted in that a portion of any non-direct force applied to them is transferred in part to the minor sup port legs through bolt 38 and then to the ground.

It will be appreciated that the most critical point in the climbing apparatus is the connection effected by

bolts

38, 38, 4t and 40 for all forces applied to the top portion of the climbing apparatus are transferred through these connections. Consequently, (referring only to a single connection) part 128 of reinforcing member 126 or 126' is connected at this point to major support leg 26 as is the substantially vertical portion of minor support leg 30. It will be seen, therefore, that this construction relieves and distributes the forces at the connection through bolt 38 from major support leg 26 of subassembly 24 to minor support leg 30 through the substantially vertical pontion 34 of minor support leg 30, and to major support leg 26 of subassembly 22 through reinforcing connection memher 126 and that the diverging

portions

138 and 140 of part 134 of reinforcing connecting member 126, being connected by their reinforcing

extensions

142 and 146 to the major support legs of the subassemblies, further reinforce this connection and prevent its buckling. The reinforcing extensions perform the further important function of reinforcing the major support legs of the subassemblies throughout their lengths, thus imparting additional structural rigidity to the major supporting legs, thereby increasing their load carrying capacity.

It will also be apparent that the force transferring ac tion of the connection afiorded by bolt 38 is followed through by interconnecting reinforcing member 48 to minor support leg 30 by bolt 62 at the point where minor support leg 30 changes direction and by connecting reinforcing member 48 to major support leg 26 by bolt 60 at the point where the reinforcing extension 142 laterally while holding on to the apparatus. Due to the tubular U-shaped configuration of U-shaped reinforcing connecting

members

104 and 106 and the manner in which they fit into the hollow ends of the major support legs, the force transferred through these members will easily be absorbed and transferred without bending them.

Also, the overturning moments caused by swinging on the U-shaped reinforcing

connector members

104, 106 and 124 of the climbing apparatus are about an axis through the transverse centerline of the climbing apparatus. Due to the outwardly extending of the major and minor support legs along the longitudinal axis of the climbing apparatus, a downward force applied to U-shaped memher 124, for example, by a childs swinging or climbing on it, acts through a very short overturnnig moment arm which is resisted by the entire weight of the climbing apparatus acting through a long resisting moment arm.

Rurther, the major and minor support legs will not buckle or sway because of the application of such a force because reinforcing connecting

members

104, 106, 124 and 126 cooperate between the support legs of the subas sembly to rigidly reinforce them with respect to each other.

members

50, 74 and '76 is effectively resisted by the force distributing effect of U-cshaped members beinding of the lower reinforcing

members

46 and 48 is resisted by supporting them from both major and minor support legs; and beinding of the major support legs is resisted in that a portion of any non-direct force of diverging leg 138 of reinforcing connecting mem her 126 connects to major support leg 26.

A modification of the climbing apparatus of FIGURES 1-8 is shown in FIGURE 9. Only those parts which differ from those in the preferred form of the invention will be described in detail and given new reference numerals.

In this modification reinforcing connecting

units

126 and 126 are replaced by reinforcing connecting units and 160. Each reinforcing connecting unit 160 and 160' comprises a horizontal tubular reinforcing part 162 having downwardly crimped

ends forming flanges

164 and 166 respectively and a tubular reinforcing part 168 having a horizontally extending portion 170 of approximately the length of reinforcing part 162 and diverging

leg portions

172 and 174. Reinforcing part 168 is welded to the central portion of reinforcing part 162, preferably along substantially the entire length of their contacting surfaces to form the rigid reinforcing connecting unit 160.

Reinforcing connecting unit 160 is connected between

subassemblies

24 and 22 intermediate their length in the following manner. The depending crimped ends 164 and 166 of part 162 are bolted to the

subassemblies

24 and 22 by previously mentioned bolt and nut assemblies 38 and corresponding bolt and nut assemblies 38', and the crimped ends 176 and 178 of part 170 are bolted to the major supporting legs of the subassemblies by previously mentioned bolt and nut assemblies 60 and corresponding bolt and nut assemblies 60. Reinforcing unit 160' is similarly connected to

subassemblies

24 and 22 by bolt and

nut assemblies

64, 64', 40 and 40.

It will be seen that this construction relieves and distributes the forces at the connection through bolt 38 from major support legs 26 of subassembly 24 to minor support leg 39 through the substantially vertical portion 34 of minor support leg 3%, and to major support leg 26 of .subassembly 22 through reinforcing connection member 160 and that the diverging

portions

172 and 174 of part 179 of reinforcing connecting member ll-6t further reinforce this connection and prevent its buckling.

The climbing apparatus embodying reinforcing units 116i and 165' is suitable for normal backyard use whereas the climbing apparatus embodying reinforcing unit 126 and 126', being of especially rugged construction in tnat the major support legs are reinforced by the reinforcing

extensions

142 and 146, is particularly adapted for use in playgrounds and the like.

It will be seen that the basic structure of the instant invention is easily adapted for either such usage by merely replacing one reinforcing connecting member with the other form thereof.

The invention may be embodied in other specific forms without departing from the spiritor essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended upper ends of the major ground. engaging support legs of the other subassembly by removable U-shaped reinforcing connecting members, such that the snbasscmblies are closer together at their upper ends than at their lower ends, the major ground engaging support legs of said subassemblies being further connected together at their central portions by a reinforcing connecting spacing member whereby said subassemblies are rigidly reinforcingly'fixed relative to each other.

2. A self-supporting, .non-tippable, rigid climbing apparatus for children having at least one rigid side framework comprising a first pair of rigid parallel bars arranged to form the bases of a trapezoid, a second pair of rigid bars crossing and interconnected to said first pair of bars at their intersection therewith by bolt and nut connections to complete said trapezoid, and bar means interconnecting at least two of the bars of said first and secondpairs of bars to immobilize the bars of said first and second pairs against relative movement and whereby said apparatus may be at least partially collapsed for storage .or shipment.

3. The apparatus of claim 2 wherein said bars are hollow metal tubes.

4. The apparatus defined in claim 2 wherein said bar means comprises a fifth bar end connecting the bars of said first pair.

5, The apparatus defined in claim 4 wherein the ends of said fifth bar are parallel and interfit with adjacent ends of said first pair of bars in removable telescopic relation.

6. The apparatus defined in claim 2 wherein said bar means comprises a fifth bar interconnecting at least one of the bars of said first pair and at least one of the bars of said second pair.

7. The apparatus defined in claim 2 wherein said bar means comprises a fifth bur extending between and fixed to the ends of the bars of said first pair.

8. The apparatus defined in claim 4 wherein the longitudinal axes of each of said bars of said second pair are in the form of obtuse angles at their connections to the bar forming the shorter base of the trapezoid.

9. A self-supporting climbing apparatus for children having'at least one rigid side framework comprising a first pair of rigid parallel bars arranged to form the bases of a trapezoid, a second pair of rigid bars crossing and interconnected to said first pair of bars at their intersection therewith by bolt and nut connections to complete said trapezoid, and a fifth bar of generally U-shaped configuration end connecting the ends of said first pair of bars to immobilize the bars of said first andsecond pairs against relative movement.

10. A self-supporting climbing apparatus comprising a pair of at least substantially identical rigid frameworks ,each composed of crossed bars defining at least one substantially equilateral trapezoid and comprising at least a pair of base forming bars and a pair of side forming bars interconnected by bolt and nut assemblies at the corners of the trapezoid and a fifth rigid bar means interconnecting at least two of the bars of said pairs of bars to immobilize the bars of said pairs against relative motion; and means rigidly interconnecting said pair of frameworks so that they define a substantially rectangular truncated pyramid; whereby at least a portion of said apparatus may be disassembled.

11.'The apparatus defined in claim 10 wherein said last named means comprises at each end of said apparatu a relatlvely short and a relatively long rigid bar interthe oppositely associated ones of said side forming bars,

so as to be slidably removable therefrom.

13. The apparatus defined in claim 10 wherein said last named means includes at each end a rigid bar interfitting in removable telescopic relation with the adjacent ends-of the upper base forming bars of said frameworks.

14. The apparatus defined in claim 10 wherein said fifth bar means in said frameworks interconnect said base forming bars thereof.

15. The apparatus defined in claim 14 wherein said fifth bar means in said-frameworks are bent so that their ends are parallel and interfit with the adjacent ends of said base forming bars thereof in telescopic relation.

16. The apparatus defined in claim 10 wherein said fifth bar means in said frameworks interconnect at least one of said base forming bars thereof and at least one of said side forming bars thereof.

1 7.The apparatus defined in claim 6 wherein said bar means includes ground engaging means.

References-Cited in the file of this patent UNITED STATES PATENTS Germany Mar.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3 120 955 February 11 1964 Edward T, Carlin It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3 line 15, for "60" read 50 column 6 line 9 strike out "laterally"; line 1O beginning with "while holding on to the" strike out all to and including "force" in line 43" same column 6.. I

Signed and sealed this 7th day of July 1964,

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents

Claims

2. A SELF-SUPPORTING, NON-TIPPABLE, RIGID CLIMBING APPARATUS FOR CHILDREN HAVING AT LEAST ONE RIGID SIDE FRAMEWORK COMPRISING A FIRST PAIR OF RIGID PARALLEL BARS ARRANGED TO FORM THE BASES OF A TRAPEZOID, A SECOND PAIR OF RIGID BARS CROSSING AND INTERCONNECTED TO SAID FIRST PAIR OF BARS AT THEIR INTERSECTION THEREWITH BY BOLT AND NUT CONNECTIONS TO COMPLETE SAID TRAPEZOID, AND BAR MEANS INTERCONNECTING AT LEAST TWO OF THE BARS OF SAID FIRST AND SECOND PAIRS OF BARS TO IMMOBILIZE THE BARS OF SAID FIRST AND SECOND PAIRS AGAINST RELATIVE MOVEMENT AND WHEREBY SAID APPARATUS MAY BE AT LEAST PARTIALLY COLLAPSED FOR STORAGE OR SHIPMENT.