GB1584701A

GB1584701A - Rotatable platform

Info

Publication number: GB1584701A
Application number: GB1321477A
Authority: GB
Original assignee: Waagner Biro AG
Current assignee: Waagner Biro AG
Priority date: 1976-04-02
Filing date: 1977-03-29
Publication date: 1981-02-18
Also published as: DE2710863C3; ATA237376A; AT351715B; DE2710863A1; DE2710863B2

Description

(54) A ROTATABLE PLATFORM (71) We, WAAGNER-BIRo AKTIENGESELLSCHAFT, an Austrian Body Corporate of Margaretenstrasse 70, Vienna A-1v-051, Austria, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a rotatable steel platform construction, for example a cylindrical revolving stage with stage elevators and stage lifts. evolving stages are usually designed to bear by means of a plurality of driving gears on a circular rail, a cylindrical jacket of the stage supporting the driving gears.Owing to the large diameter of a revolving stage a plurality of driving gears must be provided so that the bearing system becomes unstable and the load is distributed in an uncontrolled manner so that driving gears can be damaged as a result of overloading. Apart from these drawbacks, the circular rail has to be finished and installed very precisely which calls for great accuracy in the construction work. For these reasons manufacturing and construction costs are very high. It is an object of the present invention to reduce the expense but at the same time to comply with all requirements.

According to the present invention there is provided a rotatable steel platform construction comprising at least two horizontally disposed vertically spaced steel frames, columns connecting said frames together, and a central mounting member connected to the lower frame on the axis of rotation of the platform construction and rotatably supported by a combined bearing and slewing gear, the mounting member carrying the entire weight of the platform construction and the latter being so constructed that no moment due to its weight is transmitted to the mounting member.

The central mounting member may be connected to the lower frame by beams having low torsional rigidity, so that it is essentially free of moments deriving from the weight of the stage. Preferably, the central mounting member is a square box member the vertical edges of which are diagonally connected by vertical plates to two parallel beams in the lower frame member. In a modified construction, a vertical frame of quadilateral shape is defined by a beam in the lower horizontal frame, which beam incorporates the central mounting member, by two columns and by a tie beam in the upper horizontal frame, the vertical frame being prestressed so that the bending moment in the said lower frame beam in the vicinity of the central mounting member due to the weight of the platform construction is substantially zero, in order to avoid any transmission of moments into the mounting member.The prestressing is obtained by fitting the tie beam under tension. Preferably the columns have a closed or substantially closed cross-section of which the moments of inertia about two axes at right angles are substantially the same. The combined bearing and slewing gear is preferably a large roller or ball bearing provided with toothing which is used directly as a driving gear so that the whole drive is simplified.

The invention eliminates the need for a circular rail of large diameter which requires a solid and accurately aligned foundation of correspondingly large dimensions, in that it uses only a compact combined central bearing and slewing gear.

In order to function reliably the steel construction of a known cylindrical revolving stage is built very stiff and because of the unstable mounting causes overloading of individual driving gears. On the other hand, the construction in accordance with the invention provides an almost stable mounting, where the internal forces in the bearing can be countered by constructional measures.

The invention will now be further described by way of example with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic perspective view of a cylindrical revolving stage according to the invention; Figure 2 is a diagrammatic perspective view of a structural variant of Figure 1; and Figure 3 is a constructional detail of Fig ure 1.

Referring to the drawings, the cylindrical revolving stage illustrated in Figure 1 comprises a steel construction 1 including two vertically spaced horizontally disposed girder frames 8 and 9 connected together by columns 4. Frame 9 is at stage floor level.

The frame 8 comprises two torsionally rigid supporting beams 3 having a closed or tubular cross-section and connected together by two parallel beams 7 which possess low torsional rigidity and by floor bearers 11.

Beams which have low torsional rigidity are beams having an open cross-section e.g. a C-shaped cross-section. The frame 8 is connected with frame 9 by means of the columns 4, the columns 4 being interconnected in pairs by braces 12. The braces 12 are arranged at two opposite sides of the stage so that on the other two sides wide openings marked by the dot-dash rectangles 18, 19 are provided for bringing in scenery beneath the stage floor level to be lifted to stage level through the opening 17 which is also marked by a dot-dash rectangle. This construction enables the use of an extensive stage lift (not shown), possibly divided into several small lifts which fill the whole opening 17. The upper frame 9 comprises horizontal main beams S connected to the columns 4 and out-rigger bearers 13 for the stage floor.

The revolving stage includes a central mounting member 2 which is located on the axis of rotation of the stage and is connected to the lower steel frame 8 by means of vertically arranged plates 6 of low torsional rigidity. The mounting member 2 is supported from below by a combined bearing and slewing gear which carries the entire weight of the revolving stage at a central position and rests on a foundation (not shown). Because of the low torsional rigidity of the plates 6 and beams 7 only vertical forces are transmitted to the mounting member 2 and the bearing and slewing gear are thus kept free of moments.

Figure 2 shows a structural variant to Figure r where the single opening 17 of Figure 1 is divided into two parts 14 each having its own lift (not shown). The frames 8 and 9 and the columns 4 are arranged to define a vertical frame of quadilateral shape composed of a single supporting beam 3, two columns 4 and a tie beam 5 of the upper frame 9. In order that the central mounting member 2 shall as far as possible be loaded by vertical forces only and free of moments, the tie beam S is fitted under tension to prestress the frame 3, 4, 5 so that due to the weight of the stage no bending moments exist in or near the central mounting member 2.

Preferably the columns 4 are of closed or substantially closed cross-section, of which the moments of inertia about two axes at right angles are substantially the same. The use of such columns in the illustrated revolving stage has the advantage that the lifts can be loaded at the lower level not only in the directions 18 and 19 but also through the openings 15 and 16 alongside the columns 4, thus facilitating especially the use of stage trucks.

As in Figure 1, both frames 8 and 9 of the revolving stage are completed by floor bearers.

Prestressing of the frame 3, 4, 5 prevents any moments caused by the dead weight of the steel construction being transmitted into the central bearing and slewing gear. Owing to the fact that moments due to live loads (actors and scenery being moved on the stage) are much smaller it is easier to counter their effects for example by increasing the bearing play.

Figure 3 shows a constructional detail of Figure 1 in plan view. The central mounting member 2 comprises a square box member 10, the vertical edges of which are diagonally connected by the plates 6, e.g. flat bars, to the parallel beams 7. By interposing the elements 6 and 7 of low torsional rigidity, any transmission of moments into the central mounting member 2 can be avoided and thus the carrying capacity of a roller bearing is not adversely affected.

WHAT WE CLAIM IS:- 1. A rotatable steel platform construction comprising at least two horizontally disposed vertically spaced steel frames, columns connecting said frames together, and a central mounting member connected to the lower frame on the axis of rotation of the platform construction and rotatably supported by a combined bearing and slewing gear, the mounting member carrying the entire weight of the platform construction and the latter being so constructed that no moment due to its weight is transmitted to the mounting member.

2. A platform construction according to Claim 1, wherein the central mounting member is connected to the lower frame by beams having low torsional rigidity.

3. A platform construction according to Claim 1 or 2, wherein the central mounting member is a square box member the vertical edges of which are diagonally connected by vertical plates to two parallel beams in the lower frame member.

4. A platform construction according to any one of Claims 1 to 3, wherein the columns are interconnected in pairs by braces.

5. A platform construction according to Claim 1, in which a vertical frame of quadilateral shape is defined by a beam in the lower horizontal frame, which beam incorporates the central mounting member,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. ure 1. Referring to the drawings, the cylindrical revolving stage illustrated in Figure 1 comprises a steel construction 1 including two vertically spaced horizontally disposed girder frames 8 and 9 connected together by columns 4. Frame 9 is at stage floor level. The frame 8 comprises two torsionally rigid supporting beams 3 having a closed or tubular cross-section and connected together by two parallel beams 7 which possess low torsional rigidity and by floor bearers 11. Beams which have low torsional rigidity are beams having an open cross-section e.g. a C-shaped cross-section. The frame 8 is connected with frame 9 by means of the columns 4, the columns 4 being interconnected in pairs by braces 12. The braces 12 are arranged at two opposite sides of the stage so that on the other two sides wide openings marked by the dot-dash rectangles 18, 19 are provided for bringing in scenery beneath the stage floor level to be lifted to stage level through the opening 17 which is also marked by a dot-dash rectangle. This construction enables the use of an extensive stage lift (not shown), possibly divided into several small lifts which fill the whole opening 17. The upper frame 9 comprises horizontal main beams S connected to the columns 4 and out-rigger bearers 13 for the stage floor. The revolving stage includes a central mounting member 2 which is located on the axis of rotation of the stage and is connected to the lower steel frame 8 by means of vertically arranged plates 6 of low torsional rigidity. The mounting member 2 is supported from below by a combined bearing and slewing gear which carries the entire weight of the revolving stage at a central position and rests on a foundation (not shown). Because of the low torsional rigidity of the plates 6 and beams 7 only vertical forces are transmitted to the mounting member 2 and the bearing and slewing gear are thus kept free of moments. Figure 2 shows a structural variant to Figure r where the single opening 17 of Figure 1 is divided into two parts 14 each having its own lift (not shown). The frames 8 and 9 and the columns 4 are arranged to define a vertical frame of quadilateral shape composed of a single supporting beam 3, two columns 4 and a tie beam 5 of the upper frame 9. In order that the central mounting member 2 shall as far as possible be loaded by vertical forces only and free of moments, the tie beam S is fitted under tension to prestress the frame 3, 4, 5 so that due to the weight of the stage no bending moments exist in or near the central mounting member 2. Preferably the columns 4 are of closed or substantially closed cross-section, of which the moments of inertia about two axes at right angles are substantially the same. The use of such columns in the illustrated revolving stage has the advantage that the lifts can be loaded at the lower level not only in the directions 18 and 19 but also through the openings 15 and 16 alongside the columns 4, thus facilitating especially the use of stage trucks. As in Figure 1, both frames 8 and 9 of the revolving stage are completed by floor bearers. Prestressing of the frame 3, 4, 5 prevents any moments caused by the dead weight of the steel construction being transmitted into the central bearing and slewing gear. Owing to the fact that moments due to live loads (actors and scenery being moved on the stage) are much smaller it is easier to counter their effects for example by increasing the bearing play. Figure 3 shows a constructional detail of Figure 1 in plan view. The central mounting member 2 comprises a square box member 10, the vertical edges of which are diagonally connected by the plates 6, e.g. flat bars, to the parallel beams 7. By interposing the elements 6 and 7 of low torsional rigidity, any transmission of moments into the central mounting member 2 can be avoided and thus the carrying capacity of a roller bearing is not adversely affected. WHAT WE CLAIM IS:-

1. A rotatable steel platform construction comprising at least two horizontally disposed vertically spaced steel frames, columns connecting said frames together, and a central mounting member connected to the lower frame on the axis of rotation of the platform construction and rotatably supported by a combined bearing and slewing gear, the mounting member carrying the entire weight of the platform construction and the latter being so constructed that no moment due to its weight is transmitted to the mounting member.

by two columns and by a tie beam in the upper horizontal frame, said vertical frame being prestressed so that the bending moment in the said lower frame beam in the vicinity of the central mounting member due to the weight of the platform construction is substantially zero.

6. A platform construction according to Claim 5, wherein the prestressing is obtained by fitting the tie beam under tension.

7. A platform construction according to Claim 5 or 6, wherein the columns have a closed or substantially closed cross-section of which the moments of inertia about two axes at right angles are substantially the same.

8. A platform construction according to any one of the preceding claims, wherein the combined bearing and slewing gear includes a roller or ball bearing.

9. A rotatable steel platform construction substantially as hereinbefore described with reference to the accompanying drawings.