US2978754A - Portable stage - Google Patents

Description

April 11, 1951 K. H. wlLsoN 2,978,754

PORTABLE STAGE INVENTOR. KERM/ r HWVLsoN .AT TORNE YS April l1, 1961 K. H. wlLsoN PORTABLE STAGE 6 Sheets-Sheet 2 Filed Nov. 16, 1959 INVENTOR.

KERM/T H WLsoN if WM ATTO/:PNE YS April 11, 1961 K.' H. wlLsoN 2,978,754

PORTABLE STAGE Filed Nov. 16, 1959 6 Sheets-Sheet 3 INVENTOR. KERM/T H. XIV/sow A TTOPNEYS April ll, 1961 K. H. wlLsoN 2,978,754

PORTABLE STAGE Filed Nov. 16, 1959 6 Sheets-Sheet 4 INV ENTOR.

Kanu/T H. W/Lso/v BY MM/f April 11, 1961 K. H. WILSON 2,978,754

PORTABLE STAGE Filed Nov. 16, 1959 6 Sheets-Sheet 5 INVENTOR. KERM/r H Wl/ soN AT TORNEYS April ll, 1961 Filed NOV. 16, 1959 K. H. WILSON PORTABLE STAGE 6 Sheets-Sheet 6 .lll

.KERM/T l. VWLsoN ATTORNEYS nited States PORTABLE STAGE Kermit H. Wilson, 7a Sico Mfg. C0., 5212 Eden Ave. S., Minneapolis, Minn.

Filed Nov. 16, 1959, Ser. No, $53,323

17 Claims. (Cl. 2011.123)

My invention relates generally to portable stages or platform structures, and more particularly to such structures which are adapted to be folded or otherwise arranged, when not in use, for easy transportation and storage.

An important object of my invention is the provision of a device as herein described, which may bey quickly and easily set up for operation by a single person, and as quickly and easily folded and moved to a suitable place of storage.

Another object of my invention is the provision of a device as set forth which, when folded, occupies a minimum of ground or oor area.

Another object of my invention is the provision of a device as set forth, having a supporting frame, ground engaging wheels on said frame for movements toward and away from the ground, a flat top element movable between operative and storage positions on said frame, and connections between the top element and said wheels whereby, when the top element is moved to an operative horizontal position, the wheels are raised out of engagement with the oor or ground to cause the top element to be supported by the frame, and whereby, when the top element is moved to its storage position, the wheels are lowered into engagement with the ground, and the frame is raised out of its engagement with the ground.

Another object of my invention is the provision of structure as set forth comprising a at top element, a frame pivotally supporting one end portion of said top element for swinging movements between a horizontally disposed operative position and a generally vertically disposed storage position, supporting means at the opposite end portion of the top element, and connections between said frame and supporting means for automatically moving said supporting means between an operative top element supporting position generally normal to the top element and a folded storage position generally parallel with the top element responsive to movements of said top element between its operative and storage positions respectively.

Another object of my invention is the provision of a platform structure or the like including a pair of flat top elements normally horizontally disposed in substantiallyr end to end relationship, a supporting frame underlying the adjoining end portions of said top elements and pivotally mounting said to-p elements for independent swinging movements between said normally horizontal positions and generally vertically disposed storage positions overlying said frame, and of means at the outer ends of 'said top elements for detachably anchoring other like structures thereto in end to end abutting relation.

Another object of my invention is the provision of folding structure of the type set forth having a plurality of top elements normally horizontally disposed in staired arrangement and supported at one end by a frame, and of means whereby said top elements may be moved simultaneously to a generally vertically disposed storage position overlying said frame, said top elements in their stor- 2,978,754 Patented Apr. 11, 1961v 2 age positions lying in a common generally vertically disposed plane.

Still another object of my invention is the provision of a folding structure as set forth which is relatively inexpensive to produce, which is light in weight and easily manipulated, and which is strong in construction and durable in use. The above, and still further highly important objects and advantages of my invention will become apparent from the following detailed specification, appended claims and attached drawings.

Referring to the drawings, which illustrate the invention, and in which like reference characters indicate like parts throughout the several views:

Fig. 1 is a view in side elevation of a preferred form of the invention disposed in its operative position, some parts being broken away;

Fig. 2 is a view corresponding to Fig. 1, but showing a different position of the parts, some parts being broken away and some parts being shown in section;

Fig. 3 is a view in end elevation of the device as positioned in Fig. 2, some parts being broken away and some parts being shown in section;

Fig. 4 is a fragmentary View in longitudinal section of the device as positioned in Fig. l; Y

Fig. 5 is a transverse section taken substantially on the line 5 5 of Fig. l;

Fig. 6 is an enlarged fragmentary detail ycorresponding to a portion of Fig. 4, but showing a diierent position of some of the parts;

Fig. 7 is a view corresponding to Fig. 1, but showing a modified form of the invention;

Fig. 8 is a View in end elevation of the structure of Fig. 7;

Fig. 9 is a transverse section'taken substantially on the line 9 9 of Fig. 7; and

Fig. l0 is a view corresponding to Fig. 3, of the modilied form of the invention illustrated in Figs. 7-9.

In the form of the invention illustrated in Figs. 1-6 inclusive, the numeral 1 indicates in its entirety, a normally horizontally disposed flat top comprising cooperating flat top elements or sections 2 and 3. The elements or sections 2 and 3 are preferably rectangular in outline, and are preferably made from rigid plywood, wood planks, or any suitable material. The top elements 2 and 3 are bolted or otherwise rigidly secured to generally rectangular brace frames 4 and 5 respectively, prefera'oly made from conventional angle iron and defining depending marginal flanges 6 and 7 respectively. The brace frames 4 and S further comprise cross brace members 8 and 9 which underlie their respective top elements 2 and 3 in spaced relation to the inner ends 2a and 3u respectively of the top elements 2 and 3.

The at top elements 2. and 3 are pivotally supported at their inner end portions 2a and 3a respectively by a' central supporting frame 1l) comprising pairs of vertically` disposed legs 11 and 12, and 13 and 14, the legs 11 and 12 being connected by a rigidY cross frame member l15;.

and the legs 13 and 14 being rigidly connected by a similar cross frame member 16. Vertically disposed rigidA arms 17 and 18 extend upwardly in spaced parallel relationship from the cross frame member 15, intermediate right arms 21 and 22 extend upwardly from the cross frame member 16 in spaced parallel relationship interme` diate the legs 13 and 114, and are pivotally connected to;

the inner end portions of respective top elements 2 and 3, as indicated at 23 and 24 respectively. The pivotall connections 19 and 23 are on a common horizontal axis extending transversely of the top 1, and the pivotal con-ff' 3 nections 2t! and 24 are on a common horizontal axis parallel to the axis of the pivotal connections 19 and 23, whereby the top elements 2 and 3 may be swung between their normally horizontal positions shown in Figs. 1 and 4, and generally vertically disposed storage positions shown in Figs. 2 and 3. rthe several members comprising the frame are preferably made from tubular steel or the like, the upper ends of the legs 1li-14 being provided with caps 25 which engage adjacent portions of the brace frames 4 and 5, when the top elements 2 and Y 3 are in their operative horizontally disposed positions, to

aid in supporting the top sections; and diametrically enlarged feet 26 are applied to the lower ends of the several legs 11-14 to prevent marring or scratching of the ground or oor upon which the frame 1G rests, the floor being indicated by the reference character X.

The outer ends of the top elements 2 and 3 are supported by respective leg structures 27 and 28, each of the leg structures comprising a pair of laterally spaced legs 29 and 30 connected by rigid cross bars 31. Like the frame 10, the leg structures 27 and 28 are preferably made from tubular metal, the legs 29 and 3i) thereof being provided with ground or iloor engaging feet 32 similar to the feet 26. The upper ends of the legs 29 and 30 of each leg structure 27 and 28 are pivotally connected to the outer end portions of respective top elements 2 and 3 as indicated at 33 and 34 respectively, see particularly Fig. 3, on aligned horizontal axes parallel to the axis of the pivotal connections at the inner ends of the top elements 2 and 3. Cooperating control arms 35 and 36 are pivotally connected at their inner ends to the legs 11 and 13 respectively, as indicated at 37, on aligned horizontal axes parallel to the axis of the pivotal connections 22 and 23. At their outer ends, the control arms 35 and 36 are pivotally connected to the legs 29 and 30 of the leg structure 27, as indicated at 38, on aligned horizontal axes parallel to the aligned axes of the pivotal connections 33 and 34 of the leg structure 27. As shown par- 4 rticularly in Fig. l, when the top element 2 is in its horizontally disposed operative position, the legs 29 and 30 of the leg structure 27 are disposed substantially at right angles to the plane of the top element 2. When the top element 2 is swung upwardly to its storage position of Fig. 2, the control arms 35 and 36 cause the legs 29 and 30 of the leg structure 27 to swing inwardly toward generally parallel relationship with the top element 2, engagement of the feet 26 of the leg structure 27 with the adjacent portions of the marginal brace frame 4 limiting swinging movement of the top element 2 beyond its storage position of Fig. 2. In the same manner, the legs 29 and 30 of the leg structure 28 are connected to respective legs 13 and 14 ofthe supporting frame 1t) by control arms 39 and 40 pivotally connected at their inner ends to the legs 12 and 14, as indicated at 41, and at their outer ends to the legs 29 and 30 of the leg structure 28, as indicated at 42. The control arms 39 and 40 operate in the same manner as the control arms and 36 to move the leg structure 28 into engagement of the feet 32 thereof with adjacent portions of the marginal frame 5 when the top element 3 is moved to its generally vertically disposed storage position of Fig. 2. It will be noted, that when the top elements 2 and 3 are in their folded storage positions of Fig. 2, that the upper ends of the arms 35, 36, 39 and 40 are disposed beyond a dead center relationship between the axis of the pivotal connections of the inner ends thereof and the axes of pivotal connection of their respective legs 29 and 30 to the outer end portions of the top elements 2 and 3. This arrangement prevents accidental movement of the top elements from their generally vertically disposed storage positions toward their operative positions, it being necessary that the outer leg structures 27 and 28 or their respective control arms 35 and 36 or 39 and 4t) be manually swung outwardly through said dead center relationship before the top elements 2 or 3 may be moved to their horizontally disposed operative positions.

With reference to Pigs. land 4, it will be seen that the inner ends 2a and 3a of the top elements 2 and 3 respectively are spaced apart when the top elements are in their horizontally disposed positions. For the purpose of spanning the gap between the adjacent inner ends 2a and 3a, l provide a rigid bridge element 43 which closely overlies the adjacent ends 2a and 3a and which is supported by rigid legs or supporting bars 44 welded or otherwise rigidly secured to the cross frame members 15 and 16. The spacing between the pivot axes of the top- elements 2 and 3, and the relationship between these pivot axes and the top surfaces of their respective top elements 2 and 3 is such that ample clearance is provided for the bridge element 43 between the top elements when the same are moved to their storage positions of Fig. 2.

For the purpose of lending mobility to the instant device, when the top elements 2 and 3 are in their folded or storage positions, whereby the structure may be easily moved to a desired location, I provide novel means now to be described. A pair of elongated rigid mounting members or bars 45 and 46 are provided at their opposite ends with vertically disposed tubular heads 47 and 48 respectively, and have mounted intermediate their ends pairs of caster wheels 49 and 50 respectively. The heads 47 of the mounting member 45 each slidably encompass one of the legs 11 and 13, the heads 48 of the mounting member 46 each slidably encompassing one of the legs 12 and 14 of the frame structure 10, for generally vertical movements relative thereto. A pair of rigid links 51 are pivotally connected at their lower ends to the mounting member or bar 45, as indicated at 52, and at their upper ends to brackets 53, as indicated at 54, The brackets 53 are welded or otherwise rigidly secured to the cross brace 8, the axes of the' pivotal connections 54 being aligned, and in spaced parallel relation to the axis of pivotal movement of the top element 2. A similar pair of rigid links 55 are pivotally secured at their lower ends on aligned horizontal axesto the wheel mounting member or bar l46, as indicated at 56, the upper ends of the links 55 being pivotally secured to brackets 57 on aligned horizontal axes, and as indicated at S8. The brackets 57 are similar to the brackets 53 and are welded or otherwise rigidly secured to the cross brace 9 of the top element 3. The axis of the pivotal connections 58 is disposed in spaced parallel relation to the axis of swinging or pivotal movement of the top element 3, and the axis of the pivotal connections 56 is parallel to both these axes.

The lengths of the rigid links 51 and 55 are such that, when the top elements 2 and 3 are disposed in their normal horizontal positions of Fig. 1, that the Wheels 49 and 50 are upwardly spaced from the ground or floor X, the legs 11-14 of the supporting frame 10 and the legs 29 and 30 of the leg structures 27 `and 28 engaging the oor'or ground X and carrying the weight of the top elements 2 and 3. When it is desired to fold the structure for movement to a place of storage, the outer ends of the top elements 2 and 3 are individually raised to their generally vertically disposed storage positions of Fig. 2. During upward swinging movement of either of the top elements 2 or 3, for example the top element 3, as shown in Fig. 6 and by dotted lines in Fig. 4, the pivotal connections 58 move in an arc about the axis of the pivotal connections 24 to cause downward movement of the wheel mounting member or bar 46, the legs 12 and 14 of the supporting frams 10 acting as guide members for the wheel mounting member 46. As the top element 3 approaches its folded or storage position, as indicated by dotted lines in Fig. 4, the wheels 50 make contact with the ground or floor X. Continuedswinging movement ofthe top element 3 in the same direction causes the legs 12 and 14 to be raised from engagement anveres with the floor X, the a-Xis of the pivotal connections 58 moving slightly beyond a dead center relationship between the axis of the pivotal connections 56 and 24. With reference to Fig. 6, it will be noted that, when the top element 3 is moved to its generally vertically disposed storage position, the supporting frame becomes tilted, the same being supported at one side by the wheels 50 and at its opposite side by the legs 11 and 13. Then, when the top element 2 is pivotally swung to its generally vertically disposed storage position, the wheels 49 move into engagement with the ground or floor X, and the legs 11 and 13 are raised out of engagement with the floor, so that the entire structure is disposed as shown in Fig. 2. In view of the fact that all of the pivotal connections between the various parts of the above-described structure are on parallel axes, it is not necessary that the top elements 2 and 3 be moved between their operative and storage positions simultaneously but that the same may be so moved in succession by a single person. This novel arrangement further eliminates any binding between the frame legs 11-14 and their respective sliding heads 47 and 48 when the supporting frame 1t) is tilted as shown in Fig. 6 during movement of one of the top elements relative to the other thereof.

'For the purpose of combining two or more structures as above described to provide a stage or platform of considerable area, I provide a plurality of upwardly opening hooks 59. One each of the hooks 59 is welded or otherwise rigidly anchored to each of the depending flanges 6 and 7 at a common side of the top 1, and one hook 59 is likewise welded to the marginal flange 7 at the outer end of the top element 3. The bottoms of the hooks 59 are disposed at or below the level of the lower edges of the anges 6 and 7, the hooks 59 being adapted to receive the depending marginal flanges of other like structures as indicated by dotted lines in Fig. l, the structures being adapted to be placed in end to end or in side by side relationship, `or both. The structures being relatively light in weight, it is an easy matter to manually raise one side or end of the structure to place the marginal ange thereof into the cooperating hooks 59 of an adjacent one of the structures to anchor adjacent structures against relative sideways or endways movement.

The over dead center relationship of the upper ends of the control arms 35, 36, 39 and 40 as well as that of the upper ends of the links 51 and 55, when the top elements 2 and 3 are in their storage positions, contributes to the stability of the top elements in these positions and insures against accidental movement of the top elements to their horizontally disposed positions during movement of the structure over rough places. It will be appreciated that, while the instant structure has been described as a stage or platform, the lengths of the various legs 11-14, 29 and 3i) may be such that the structures may be used as folding tables. Hence, the instant invention is intended to apply to tables as well as platforms or stages, the forms shown herein being illustrative of two examples thereof.

The form of the instant invention illustrated in Figs. 7-10 is commonly known in the trade as a choral riser, upon which persons may sit or stand at different levels, so that all thereon may be seen and heard with equal clarity by an audience. This modification comprises a series of elongated platforms in side by side staired arrangement, the front and lowermost platform being indicated generally by the numeral 60, the intermediate platform being indicated by the numeral 61 and disposed immediately behind the lowermost platform 60, and the uppermost platform being indicated generally by the numeral 62 and disposed immediately rearwardly of the intermediate platform 61. The lowermost or front platform 60. comprises a pair of elongated platform elements 63 and 64, the intermediate platform comprising a similar pair of platform elements 65 and 66, and the uppermost Si or rear platform 62 including a pair4 of similar platform elements 67 and 68, the cooperating platform elements of each of said platforms being normally horizontally disposed in end to end relationship, see Fig. 7. At their inner ends, the several platform elements are pivotally connected to a frame structure, indicated generally at 69, the frame structure 69 comprising a plurality of rigid frame sections 70, 71, 72 and 73. The frame section 70 comprises a pair of vertical legs 74 and 75, a horizontally disposed bar 76 rigidly connecting the legs 74 and 75, and a pair of upright members 77 and 78 to the upper ends of which are pivotally secured the inner end portions of the platform elements 63 and 64, as indicated at 79. The frame section 71 comprises a pair yof vertical legs 80 and 81 and a rigid connecting cross bar 82, the legs 86 and 81 being spaced apart a distance equal to the spacing between the upright members 77 and 78, the inner end portions of the intermediate platform elements 65 and 66 being pivotally secured to the upper ends of respective legs 80 and 81 on horizontal axes parallel to and vertically spaced from the axes of the pivotal connections 79, as indicated at 83. With reference to Figs. 9 and l0, it will be seen that the inner end portions of the lowermost front platform elements 63 and 64 are also pivotally connected to respective ones of the legs 80 and 81, as indicated at 84, on axes aligned with the yaxes of the pivotal connections 79. The frame section 72 comprises a pair of vertically extending legs 85 and 86 spaced apart a distance equal to the spacing between the legs 80 and 81 of the frame section '71, and rigidly connected by a rigid cross bar 87, the inner end portions of the uppermost rear platform elements 67 and 68 being pivotally connected to the upper ends of respective legs and 86, as indicated at 88 on horizontal axes parallel F to and upwardly spaced from the axes of pivotal movement of the platform elements of the intermediate and front platforms 61 and 60 respectively. With reference to Figs. 9 and l0, it will be seen that the inner end portions of the intermediate platform elements 65 and 66 are pivotally connected to the legs 85 and 86 respectively, as indicated at 89, on aligned aXes with respective ones of the pivotal connections 83. The rearmost frame section 73 comprises a pair of vertically extending legs 90 and 91 rigidly connected by a cross member 92 in spaced relation equal to the spacing of the legs 74 and 75. The frame section 73 further includes a pair of upright members 93 and 94, see Figs. 9 and l0, that are spaced apart a distance equal to the spacing between the legs 85 and 86, the inner end portions of the platform elements 67 and 68 being pivotally connected to respective ones of the upright members 93 and 94, as indicated at 95, on horizontal axes aligned with-the axes of respective ones of the pivotal connections 88.

With reference to Fig. 7, it will be seen that the adjacent inner ends of the cooperating elements comprising the several platforms 60, 61 4and 62 are disposed in closely spaced relationship, when the platform elements are in their normally horizontally disposed operative positions. In order to cover the spaces between the respective platform elements of each platform, I provide horizontally disposed flat topped bridge elements 96, 97 and 98 for the platforms 60, 61 and 62 respectively. The front end of the bridge element 96 is supported from the cross bar 76 by a rigid leg 99, the front end of the bridge element 97 being supported by a rigid leg 100 extending upwardly from the cross member S2, and the front and rear ends respectively of the bridge element 93 being supported by legs 101 and 102 extending upwardly from the cross bars 87 and 92 respectively. The rear end of the bridge element 96 is welded or otherwise rigidly secured to the leg 100, whereas the rear end of the bridge element 97 is Iwelded or otherwise rigidly secured to the leg 101, the several bridge elements 96, 97 and 98, together with their respective supporting legs rigidly tying the several frame sections 70-73 together.

'1"he platform elements 63, 65 and 67 are supported at their outerv end portionsin their normally horizontally disposed operative positions by a leg structure 103, and the platform elements 64, 66 and 68 are similarly supported by a corresponding leg structure 104. Each of the leg structures 103 and 104 comprises a plurality of outer legs 105, 106 and 107, the upper ends of the legs 105 being pivotally connected to the adjacent end portions of their respective platform elements 65, as indicated at 108, for pivotal movements relative -to their respective platform elements on horizontal axes parallel to the axes of the pivotal connections at the inner ends of the platform elements. The outer ends of the platform elements 63 and 64 are likewise pivotally secured to adjacent legs 105, as indicated at 109, see Figs. 8 and l0. The outer ends of the platform sections 65 and 66 are pivotally connected to the intermediate portions of adjacent legs 106 of their respective leg structures 103 and 104, as indicated at 110, on horizontal axes aligned with the axes of their respective pivotal connections 108. The outer ends of each of the platform elements 67 and 68 are pivotally connected to the upper ends of the legs 106 and 107 of their respective leg structure 103 and 104, on aligned axes as indicated at 111. The legs 105 and 106 of each of the leg structure 103 and 104 are rigidly connected by cross members 112, and the legs 106 and 107 are similarly connected by cross members 113. The outer ends of the lowermost or front platform elements 63 and 64 are further supported by relatively short legs 114 that are rigidly secured to the outer 'end portions of their respective platform elements 63 and 64.

It will be noted that the pivotal connections between the outer ends of the groups of platform sections and their respective leg structures 103 and 104 are in Vertically spaced relationship like the relationship between the pivotal connections of the inner ends thereof to the frame structure 69, all of these pivotal connections being parallel. With this arrangement, the platform elements 63, 65 and 67 may be swung upwardly about the axes of their pivotal connections 79, 83 and 88 respectively to a generally vertically disposed storage position wherein the several platform elements 63, 65 and 67 are disposed in a common plane, as indicated by dotted lines in Fig. 7. The platform elements 64, 66 and 68 may be likewise swung upwardly to a similar storage position, independently of the group of platform elements 63, 65 and 67. It will be further noted that, when the several platform sections are moved to their storage positions, their respective leg structures 103 and 104 move between positions generally normal to the planes of their respective platform sections and inoperative folded positions generally parallel to their respective platform elements. The legs 114, being relatively short, there is no necessity for pivotally connecting the same to their respective platform elements 63 and 64, inasmuch as the legs 114 project outwardly from the platform elements but a short distance when said platform elements are in their storage positions.

A pair of elongated mounting members 115 and 116 are provided at their opposite ends with vertically extending tubular heads 117 and 118 respectively, the heads 1117 each slidably encompassing a different one of the legs 74 and 90 of the frame structure 69, the heads 118 each llikewise slidably encompassing a different one of the legs 75 and 91. Intermediate their ends, the mounting members 115 and 116 are provided with spaced groundengaging caster Wheels 119 and 120 respectively. Adjacent their front ends, the mounting members 115 and l116 are provided with depending rigid iingers 121 to the lower ends of which are pivotally secured the opposite ends of a connector bar 122. A rigid link 123 is pivotally connected at its lower end to the connector bar 122 in closely spaced relationship to the pivotal connectionvof the connector bar 122 with the depending nger 1.21 'of the 8. mounting member 115, the upper end of the link 123 being pivotally connected toa bracket 124 rigidly secured to the inner end portion of the platform Velement 63. A rigid link 125, similar to the 4link 123, ispivotallyv connected to the connector bar l122 closely adjacent the linger 121 of the mounting member 116, and to a bracket 126 rigidly secured to the inner end portion of the platform section 64. Other rigid links 127 and 123 are pivotally secured at their lower ends to the rear end portions of the mounting members and 116 respectively, and at their upper ends to brackets 129 and 130 rigidly secured to the inner end portions of the platform elements A67 and 68 respectively. The several links 123, 125, 127 and 128 operate to lower the mounting members 115 and 116 into engagement of their respective wheels 119 and 120 with the floor or ground, and raise the `frame structure 69 out of engagement with the ground, when the several platform elements are pivotally swung to their dotted line storage positions of Fig. 7; and to raise the wheels out of engagement with the door or ground and lower the frame structure 69 into platform supporting engagement with the floor or ground when the several platform elements are moved to their horizontally disposed operative positions indicated by full lines in Fig. 7. This operation is identical to that above described with respect to the form of the device illustrated in Figs. 1 6. With the above arrangement, raising of one of the staired groups, for example, the group comprising the platform elements 64, 66 and 68, causes the rigid link 125 to exert downward pressure on the adjacent end portion of the connector bar 122, the connector bar 122 swinging downwardly on the axis of its pivotal connection to the opposite iinger 121 depending from the mounting member 115. In other Words, the connector bar 122 functions as a lever to transfer downward movement of the link to the adjacent end portion of its respective mounting member 116. Obviously, lowering of the platform elements 64, 66 and 68 will cause the connector bar 122 to swing upwardly on the above mentioned axis. Moving the opposite group of platform elements 63, 65 and 67, either upwardly or downwardly, will cause the connector bar 122 to swing in a corresponding direction about the axis of its pivotal connection to the iinger 121 depending from the opposite mounting member 116, whereby to lower or raise the adjacent end of the mounting member 115.

Preferably, the platform elements of one staired group thereof, such as the platform elements 64, 66 and 68, may be provided with upwardly opening hooks 131 at the outer ends thereof whereby another choral riser may be releasably anchored to the one above described in the same manner as hereinbefore disclosed in connection with the form of the invention illustrated in Figs. 1-6.

While I 'have shown and described two embodiments or forms which my invention may take in actual practice, it will be understood that the same is capable of vfurther modification, without departure from the spirit and scope of the invention as defined in the claims.

What I claim is:

1. In a device of the kind described, a normally horizontally disposed generally dat top element, a supporting frame for one end portion of said top element, supporting means for the opposite end portion of said top element, means pivotally connecting said one end portion of the top element to said frame `for swinging movements of said top element between its normally horizontal position and a generally vertically disposed storage positionand on a horizontal axis generally parallel to the adjacent end of said top element, a plurality of wheels, wheel carrying means mounted on said frame for movements toward and away from supporting engagement of said wheels with the ground, and linkage operatively connected to said top element and the wheel carrying means and responsive to movement of said top element to its normally horizontal position to move said wheel carrying means upwardly whereby said supporting frame 'rests upon 'the gr ground, said linkage being responsive to movement of said top element to said storage position to lower said Wheel carrying means into engagement of said wheels with the ground and elevate said frame from engagement with the ground.

2. In a device of the kind described, a normally horizontally disposed generally at top element, a supporting frame for one end portion of said top element, leg structure pivotally connected to the opposite end portion of said top element for swinging movements between a top element supporting position generally normal to said top element and a storage position generally parallel to said top element, means pivotally connecting said one end portion of the top element to said frame Ifor swinging movements between its normally horizontal position and a generally vertically disposed storage position and on a horizontal axis generally parallel to the adjacent end of said top element, a plurality of wheels, wheel carrying means mounted on said frame yfor movements toward and away from supporting engagement of said wheels with the ground, and linkage operatively connected to said top element `and the Wheel carrying means and responsive to movement of said top element to its normally horizontal position to move said wheel carrying means upwardly `whereby said supporting frame rests upon the ground, said linkage being responsive to movement of said top element to said storage position to lower said wheel carrying means into engagement of said wheels with the ground and elevate said frame from engagement with the ground.

3. The structure defined in claim 2 in which the axis of pivotal movement of said leg structure is parallel to the axis of swinging movement of said top element, and in further combination with a rigid control arm pivotally secured to said frame and said leg structure for automatically moving said leg structure between its operative and storage positions during movement of said top element toward its normally horizontal and vertically disposed storage positions respectively.

4. In a device of the kind described, a normally horizontally disposed generally flat top element, a supporting frame for one end portion of said top element, supporting means for the opposite end portion `of said top element, said frame defining spaced parallel generally vertical guide members, means pivotally connecting said one end portion of the top element to said frame for swinging movements of said top element between its normally horizontal position and a generally vertically disposed storage position and on a horizontal axis generally parallel to the adjacent end of said top element, a plurality of wheels, wheel carrying means mounted lon said guide members for movements toward and away from engagement of said wheels with the ground, a rigid link pivotally secured at one end to said wheel carrying means and at its other end to said top element' on axes parallel to the axis of swinging movement of said top element, the axis of the pivotal connection between said link and said top element being generally downwardly spaced from the axis of swinging movement of said top element, said link being responsive to movement of said top element to its normally horizontal position to move said wheel carrying means upwardly relative to said frame whereby said frame rests upon the ground, said linkage being responsive to movement of said top element to said storage position to lower said wheel carrying means into engagement of said wheels with the ground and elevate said frame from engagement with the ground, and means limiting said swinging movement of said top element beyond said storage position.

'5. The structure defined in claim 4 in which said frame includes va support portion engaging said top element in its lnormally horizontal position to support said top element intermediate the pivotd connecting means of said top element and said supporting means.

6. lIn a device of the kind described, a top comprising tween their normally horizontal positions and generallyV vertically disposed storage positions and on horizontal axes parallel to said inner ends of the top elements, a plurality of wheels, a pair of wheel carrying members one each underlying a different one of said top elements when in their horizontal positions and each mounted on said frame structure for independent movements toward and away from engagement of the Wheels with the ground, linkage operatively connected to said top elements and to underlying ones of said wheel carrying members and responsive to movement of the respective top elements to their normally horizontal positions t'o move their respective wheel carrying members upwardly whereby the frame structure rests upon the ground, said linkage being responsive to movement of said top elements to said storage positions to lower ther respective wheel carrying members into engagement of the wheels thereof with the ground and elevate said frame from engagement with the ground, and means limiting said swinging movement of said top element beyond said storage position.

7. The structure dened in claim 6 in which said supporting frame structure includes pairs of generally vertically extending legs, the legs of each pair thereof being spaced apart longitudinally of said device, each pair thereof being spaced apart transversely of said device, said wheel carrying members each comprising an elongated bar extending transversely of said device and each slidably mounted at its opposite ends on one of the legs of each pair thereof.

8. The structure dened in claim 6 in which said supporting means for the outer ends of said top elements comprises la pair of independent leg structures each pivotally connected to the outer end portion of a different one of said top elements for swinging movements between a top element supporting position generally normal to its respective top element' and a storage position generally parallel to its respective top elements, the axes of swinging movements of said leg structures being horizontal and parallel to the axis of swinging movement of said top elements on said frame, said last mentioned means comprising rigid control arms pivotally secured to said frame and said leg structures and automatically moving said leg structures between their operative positions and their storage positions during movement of said top elements toward their normally horizontal and vertically disposed storage positions respectively.

9. In a device of the kind described, a normally horizontally disposed flat top element, a supporting frame for one end portion of said top element, supporting means for the opposite end portion of said top element', said opposite end of the top element defining a depending flange, means pivotally connecting said one end portion of the top element to said frame for swinging movements of said top element between its normally horizontal position and a generally vertically disposed storage position and on a horizontal axis generally parallel to the adjacent end of said top element, a plurality of wheels, wheel-carrying means mounted on said frame for movements toward and away from supporting engagement of said wheels with the ground, linkage operatively connected to said top element and the wheel carrying means and responsive to movement of said top element to its normally horizontal position to move said wheel-carrying means upwardly whereby said supporting frame rests upon the ground, said linkage being responsive to movement of said top element to said storage position to lower said wheel-carrying means into engagement .of said wheels with the ground and elevate said frame from engagement with the ground, means vgevaren 11 limiting said swinging movement of said top element beyond said storage position, and an upwardly opening hook element on said depending ange, the bottom of said hook element being downwardly spaced from the top surface of the top element at least as far as the lower edge of said flange, said hook element being adapted to receive the flange of a second top element placed in end to end abutting relation to said inst-mentioned top element, whereby to anchor said top elements against relative longitudinal displacement.

l0. in a device of the kind described, a top comprising a pair of normally horizontally disposed ilat top elements having spaced parallel inner ends, a supporting frame structure underlying the adjacent inner ends of said top elements, supporting means for the outer end portions of said top elements, means pivotally connecting the inner end portions of said top elements to said frame structure for independent swinging movements of said top elements between their normally horizontal positions and generally vertically disposed storage positions and on horizontal axes parallel to said inner ends of the top elements and spaced from the inner ends of their respective top elements in the direction of the outer ends thereof, a plurality of wheels, a pair of wheel-carrying members one each underlying a different one of said top elements when in their horizontal positions and each mounted on said frame structure for independent movements toward and away from engagement of the wheels with the ground, linkage operatively connected to said top elements and to underlying ones of said wheel-carrying members and responsive to movement of their respective top elements to their normally horizontal positions to move their respective wheel-carrying members upwardly whereby the frame structure rests upon the ground, said linkage being responsive to movement of said top elements to said storage positions to lower their respective wheel-carrying members into engagement of the wheels thereof with the ground and elevate said frame from engagement with the ground, means limiting said swinging movement of said top elements beyond said storage positions thereof, and a bridge element mounted on said f-rame structure and spanning the space between the inner ends of said top elements substantially at the level of the top surface of said top elements when said top elements are disposed in their horizontal positions. 1l. The structure dened in claim l0 in which said bridge element is disposed immediately above the plane of the top surfaces of said top elements, said bridge element having a width greater than that of the space between said top elements in their horizontal positions, whereby to overlap said adjacent end portions of the top elements.

l2. In a device of the kind described, a normally horizontally disposed generally flat top element, a supporting frame for one end portion of said top element, supporting means for the opposite end portion of said top element, means pivotally connecting said one end portion of the top element to said frame for swinging movements of said top element between its normally horizontal position and a generally vertically disposed storage position and on a horizontal axis generally parallel to the adjacent end of said top element, a plurality of wheels, wheel carrying means mounted on said frame for movements toward and away from supporting engagement of said wheels with the ground, a rigid link pivotally secured at one end to said wheel-carrying means and at its other end to said top element on axes parallel to the axes of swinging movement of said top element, the axis of the pivotal connection between said link and said top element being generally downwardly spaced from the axis of swinging movement of said top element, said link being responsive to movement of said top element to its normally horizontal position to move said wheel carrying means upwardly relative to said frame whereby said frame rests upon the ground, said link being responsive to` movement of said top element to said storage position to lower Said wheel carrying means into engagement of said wheels with the ground and elevate said frame from engagement with the ground, and a control arm pivotally connected to said supporting frame and said supporting -means to limit said pivotal movement of said top element in the direction of said sto-rage position, said other end of the link being disposed at one side of dead center relationship between the pivot axis of swinging movement of said top element and the axis of pivotal connection of said link to said wheel-carrying means when the top element is moved to said storage position, said other end of the link moving to the other side of said dead center relationship during initial movement of said top element toward its horizontal position.

13. 1n a device of the kind described, a plurality of elongated at platform elements, a supporting frame, means for pivotally mounting said platform elements at one end to said supporting frame on generally vertically spaced horizontal axes substantially parallel to the adjacent ends of said platform elements for movements between parallel horizontally disposed operative positions in staired arrangement and generally vertically disposed inoperative storage positions overlying said frame, a support pivotally connected to the other end of each of said platform elements on generally vertically spaced horizontal axes parallel to the pivot axes at said one end, whereby said platform elements partake of simultaneous movement between said operative positions and said storage positions, a plurality of wheels, wheel carrying means mounted on said frame for movements toward and away from engagement of said wheels with the ground, and linkage operatively connected to one of said platform elements and to said wheel-carrying means and responsive to movement of said platform elements to their operative horizontal positions to move said wheel carrying means upwardly whereby said supporting frame rests upon the ground, said linkage being responsive to movement of said platform elements to said storage positions to lower said wheel-carrying means into engagement of said wheels with the ground.

14. In a device of the kinddescribed, a plurality of elongated flat platform elements, a supporting frame, means for pivotally mounting said platform elements at one end portion to said frame on vertically spaced horizontal axes substantially parallel to the adjacent ends of said platform elements for movements between parallel horizontally disposed operative positions in staired arrangement and generally vertically storage positions overlying saidframe, a rigid support pivotally connected to the other end of each of said platform elements on vertically spaced horizontal axes parallel to the pivot axes at said one end whereby said platform elements partake of simultaneous movement between said operative positive positions and said storage positions, said pivot axes being so arranged that said platform elements are disposed in a common plane in said storage positions thereof, a plurality of wheels, wheel carrying means mounted on said frame for movements toward and away from engagement of said wheels with the ground, and linkage operatively connected to one of said platform elements and to said wheel carrying means and responsive to movement of said platform elements to their operative horizontal positions to move said wheel carrying means upwardly whereby said supporting frame rests upon the ground, said linkage being responsive to movement of said platform elements to said storage positions to lower saidpwheel carrying means into engagement of said wheels with the ground.

15. The structure defined in claim 14 in which said support comprises leg structure movable between an operative supporting position substantially normal to said platform elements in their horizontally disposed positions andninoperative folded positions generally parallel to and lying against adjacentsurfacesfof said platform elements 13 in their storage positions, whereby to limit swinging movements of said platform elements beyond said storage positions.

16. In a device of the kind described, a plurality of platforms normally horizontally disposed in staired arrangement, each of said platforms comprising a pair of elongated platform elements normally in aligned closely spaced end to end relationship, -a supporting frame underlying the adjacent inner end portions of said platform elements, means pivotally connecting the adjacent end portions of said platform elements to said frame `on parallel horizontal axes extending substantially parallel to the inner ends of said platform elements, the axes of pivotal connection of the platform elements of each platform being vertically spaced from the pivot axes of other platform elements of a staired group thereof, whereby said platform elements are movable between their normally horizontal operative positions and generally vertically disposed storage positions overlying said frame, a pair of rigid leg structures each pivotally secured to the outer ends of the platform elements of a different staired group thereof on vertically spaced horizontal axes parallel to the pivot axes at the inner end portions of said platform elements and causing the elements of eaoh staired group thereof to move simultaneously between said horizontal and generally vertical positions, said leg structures being disposed generally normal to their respective platform elements when said elements are in their horizontally disposed positions, said leg structure being disposed generally parallel to and engaging adjacent surface portions of their respective platform elements in the generally vertical storage positions thereof, a plurality of wheels, a pair of wheel-carrying members one each underlying a different staired group of said platform elements when in their horizontal positions and each mounted on said frame structure for independent movements toward and away from engagement of their respective wheels with the ground, and linkage operatively connected to said staired groups of platform elements and to underlying ones of said wheel-carrying members and responsive to movement of their respective groups of platform elements to their normally horizontal positions to move their respective wheel-carrying members upwardly whereby the frame structure rests upon the ground, said linkage being responsive to movement of said groups of platform elements to said storage positions to lower their respective wheel-carrying members into engagement of the wheels thereof with the ground and elevate said frame from engagement with the ground.

17. rPhe structure defined in claim 16 in which said linkage comprises a pair of rigid links, each pivotally connected at its upper end to the inner end portion of one of the platform elements of a different staired group thereof on a horizontal axis in generally downwardly spaced parallel relation to the pivot axis of its respective platform element, the lower end of each link being pivotally secured to an underlying one of said wheel carrying members on an axis parallel to the axis of pivotal connection of the upper end of each link to its respective platform element.

No references cited.

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