GB2265653A

GB2265653A - Temporary structure

Info

Publication number: GB2265653A
Application number: GB9206566A
Authority: GB
Inventors: Ronan Peter Willson; Paul Devine; John Aitken
Original assignee: METEORLITES PRODUCTIONS LIMITE; British Broadcasting Corp
Current assignee: METEORLITES PRODUCTIONS LIMITE; British Broadcasting Corp
Priority date: 1992-03-25
Filing date: 1992-03-25
Publication date: 1993-10-06
Also published as: GB9206566D0

Abstract

A prefabricated stackable unit (4) for use in the erection of a temporary structure includes a stepped section which is movable between a plurality of positions and leads from a lower surface to an upper surface of the unit. At each corner of the unit (4) there is a quick release bolt which is retained in a recess in a plate. When two units are brought together the bolt can be inserted into a hole in a plate on the second unit and locked therein. A base unit (2) has a castor (48) carried on a spigot (58) disengaged position to a surface engaged position to hold the at each corner. A brake (16) is movable from a surface base unit in position on the surface. <IMAGE>

Description

TEMPORARY STRUCTURE This invention relates to a temporary structure and in particular to a temporary structure of the type which might be used as a tower for a camera in TV or film studios or might be used to provide temporary access to high objects.

Another aspect of the invention relates to a castor and an associated braking arrangement which may be used on any wheeled object, including the temporary structure.

In the past scaffolding type constructions have been used to provide temporary structures and these are formed from a plurality of tubes fixed together with removable joints. For more rigid structures such as those required in television and film studios, and as might be used to provide access to high ceilings and the like, collapsible tower structures have been used. These comprise prefabricated generally rectangular constructions formed from a plurality of scaffolding type tubes welded together. These form, for example, the walls of a tower and additional bracing members are fitted between these to give the structure rigidity. The tubes are fitted with spigots for fixing two of the constructions together. These spigots can easily be bent or damaged Such structures rely on their rigidity of the strength of the clips used to fix the various sections and bracing members together.

These are not generally built to particular high tolerances and towers constructed using such techniques generally lack the type of rigidity desired for mounting cameras and for conducting delicate work at a height.

It is usual for such towers to be mounted on castors so that they may be moved easily from one location to another within a building without dismantling the tower. The use of such castors gives a very small contact area with the floor on which the tower is positioned and this reduces its stability. The castors are typically provided with some form of braking device which acts on the wheels to prevent the tower from moving once it is in a desired position.

When putting such a tower together it is necessary to climb to the top to add on new tower sections to increase the height. This entails either climbing up the tower sections or using a ladder and carrying the additional sections up to the top. This can lead to accidents.

Preferred embodiments of the present invention seek to provide a temporary structure, such as a tower, which can be very simply put together, preferably without any need to climb up the tower during its construction. The structure is designed to be extremely rigid.

An improved braking device is also provided.

The invention is defined in its various aspects with more precision in the appended claims to which reference should now be made.

A preferred temporary structure embodying the various aspects of the invention will now be described in detail by way of example with reference to the accompanying figures in which: Figure 1 shows a temporary tower embodying various aspects of the present invention; Figure 2 shows a side view of the top unit of the tower of figure 1; Figure 3 shows a side sectional view of a caster on which the tower of figure 1 is mounted and its associated braking device in the engaged position; Figure 4 shows a side view of the castor of figure 2 with the braking device disengaged; Figure 5 shows a cross section through a pair of gusset plates and a quick release bolt for fixing units of the tower together; Figure 6 shows a plan view of the lower gusset plate of figure 5; Figure 7 shows a cross section on the line X-X of figure 6; Figure 8 shows a perspective view of an intermediate tower unit; and Figure 9 shows a cross section through the mounting arrangement for a ladder section in a tower unit.

The tower of figure 1 is formed from four prefabricated units.

These are a base unit 2, two intermediate units 4, and a top platform unit 6. Each of the units is formed from a plurality of tubes welded together. These are arranged in a pattern of vertical tubes 8, horizontal tubes 10, and diagonal bracing tubes 14. The tubes are of metal such as aluminium and preferably the vertical and horizontal tubes are 48.3mm diameter scaffolding type tubes and the bracing tubes are 38mm diameter. The use of standard scaffolding size tubes enable other standard scaffolding fixings to be used to attach other fittings to the units of the tower. This example tower is 4 metres high.

The base unit 2 of the tower is mounted on six castors each retained within an aluminium cup 16 which acts as a braking device for the castor. This will be described in more detail below.

The top unit 6 has a platform 18 surrounded by a toe plate 20 and a hand rail 22. At one side of the platform 18 there is a hole to receive the top end of a ladder 26 which passes through the base and intermediate units. The mounting of this ladder within each of the unit will be described in more detail below.

On the top unit 6 adjacent the top of the ladder is an arrival platform 28. Access to the main area of the platform 18 is provided through a gate 30. This gate 30 is mounted on spring loaded hinges so as to keep it shut in the absence of an opening force. At the other side of the platform there are a pair of gates 32 which open inwardly and enable equipment to be brought to the top of the tower on a forklift truck. These gates are also mounted on spring loaded hinges with stop members arranged such that the gates will not open outwardly of the platform. The gates 32 are locked in their closed position by means of bolts (not illustrated) which slide vertically in the gates and locate in holes 34 provided in the platform 18. Two further holes 36 are provided in the platform 18 to lock the gates in the open position.

Also positioned on the top unit 6 is a pulley 38. This is positioned on a diagonal bar 40 located at the head of the well formed above the ladder sections in the base and intermediate tower units. This pulley can be used to hoist small loads, such as a lamp, to the top of the tower.

A side view of the top unit 6 is shown in figure 2. This shows two boots situated beneath the platform 18 which receive the forks of a forklift truck This enables the top unit to be lifted and positioned on top of an intermediate unit 4 or the base unit 2.

When the tower is being erected from the various units the procedure is as follows. Firstly the forks of the forklift truck are inserted into the boots 42 in the top unit 6 and this is raised from the ground. It is then placed on an intermediate unit 4. It is secured to this intermediate unit 4 by means of quick release bolts mounted in gusset plates on the top corners of the intermediate unit and received by gusset plates in the lower corners of the top unit 6. The exact arrangement of these gusset plates will be described in more detail below.

Once the top unit and the first intermediate unit have been secured together it is possible to adjust the portion of the ladder 26 located in that intermediate unit such that it emerges at the arrival platform 28 in the top unit 6. Adjustment is facilitated by the fact that the section of the ladder 26 in the intermediate section is mounted on runners 44 which enable it to be slid horizontally along rails 46 at the top and bottom of the intermediate section. A locking device enables it to be secured at the desired location with its top end adjacent the arrival platform 28. The exact arrangement of runners and an example of a locking device for use with the ladder section will be desribed in more detail below.

The thus joined top and intermediate unit are then lifted further above the ground by the forklift truck, the next intermediate unit 4 is positioned beneath them and they are then lowered onto it. A similar arrangement of quick release bolts and gusset plates is provided to enable the units to be joined together. The section of the ladder 26 in the second intermediate unit is then slid to a position adjacent the bottom of the ladder unit in the first intermediate section of the tower where it is locked in position.

The two intermediate units 4 and the top unit 6 are then lifted onto the base unit 2 using the forklift truck. Again quick release bolts and gusset plates join the base unit and the intermediate unit and the section of the ladder 26 in the base unit is slid to a position adjacent the ladder section in the second intermediate unit where it is then locked.

It will be appreciated that using this method of construction the forklift truck only has to be inserted into one unit of the tower and the whole tower is erected by lifting units, which have been fixed together from the top unit and positioning the whole on a further tower unit beneath them. Using this method of construction of the tower it is never necessary for anybody to leave the ground in putting the tower together. The largest unit of the tower in this example is the base unit which is 2 metres high whilst the two intermediate sections are each 1 metre high. Thus all the quick release bolts which have to be tightened to hold the tower sections together can be reached from the ground.

Once assembled the tower can be moved about on castors 48 which are illustrated with reference to figures 4 and 5. Each castor 48 is mounted on an axle 50 coupled to a flange member 52. This flange member 52 carries a pin 54 which is received in a hole 56 in a spigot 58. The spigot 58 has two bolts 60 mounted transversely in it and these are received by holes in the lower portions of the vertical scaffold tubes 8 in the base section 2 to secure the castors to the scaffold tubes. The spigot 58 has a threaded section 62 preferably formed of metal such as steel on which a metal (steel) ring 64 having a corresponding internal thread is mounted. This steel ring 64 includes a flange 66 which is used to fix the ring 64 to an aluminium cup 16. Mounted on the lower edge of the cup 16 is a nylon ring 62.

The aluminium cup 16 is movable by means of the threaded ring 64 and the threaded section 62 of the spigot between the position shown in figure 4, in which the lower face of the nylon ring 62 is in contact with the surface on which the castor moves thereby exerting a braking force and preventing further movement, and the position shown in figure 5, in which the cup has been spun on the threaded section 62 to a position where it is above and spaced from the surface on which the castor 48 moves. Using this braking arrangement for the castors whereby the braking action acts on the floor around the castor rather than on the castor itself increases the area in contact with the floor substantially above the small castor area which would be in contact with conventional braking systems.This leads to a significant increase in stability of the tower by virture of this increased contact area and improved overall base width.

Nylon has been proposed as a good contact material for the braking surface in this example but clearly others can be used in dependence on the surfaces on which the tower is to be used.

The cups 16 can also be used to lift the castors off the floor completely by further rotation of the cups 16. This can be facilitated by providing the cup 16 with a further flange of larger diameter than the cups or with a hole in which a lever could be located. Using this arrangement would add still further to the stability of the tower by increasing the proportion of the weight of the tower carried by the cups 16.

In the example of figure 1 six cup enclosed castors are shown. In an alternative embodiment cup enclosed castors are only provided at the corners of the tower and the two intermediate castors will be replaced with castors having conventional quick release type braking mechanisms which act on the castor wheels. Using these the tower can be positioned at a desired location the conventional braking mechanism applied and the position checked prior to securing the tower in that location with the cups 16 at the corners.

A pair of gusset plates at the corners of two adjacent units of the tower of figure 1 are shown in partial cross section in figure 5.

A first plate 68 is fixed to the lower side of one of the tower units, e.g. an intermediate unit 4 and a second gusset plate 70 is fixed to the upper side of a tower unit located immediately beneath that tower section e.g. the lower unit 2. When the intermediate unit 4 is lowered onto the base unit 2 the gusset plates 68 and 70 come together in the direction of the arrows A and may make contact.

The lower gusset plate 70 includes a recess 72, a plan view of which can be seen in figure 6. This recess has a generally circular central portion and two elongate wing portions 74. A hole 76 passes from the recess through to the lower side of the gusset plate 70. A quick release bolt 78 passes through the hole 76 and is held in the recess by two wing portions 80 which locate in the wing portions 74 of the recess 72. Once the bolt has been thus positioned by insertion from the upper side of the gusset plte 70 a washer 82 is placed over the lower end of the quick release bolt and then a nut 84 is screwed on to a threaded portion 86 of the quick release bolt. A pin 88 is then passed through a transverse hole in the lower end of the quick release bolt to give a lever with which to turn the bolt.

The upper gusset plate 68 contains a hole 90 which is of similar cross section to that of the recess 72 shown in figure 6. A stop plate 92 is fixed to the gusset plate 68 above the hole 90.

When the gusset plates are brought together the quick release bolt 78 can be pushed upwards in the direction of the arrow B through the hole 90, the wing portions 80 passing through wings in the recess 90. The bolt is then returned through an angle such that the wing portion 80 of the bolt abut the upper face of the gusset plate 68 adjacent the circular portion of the hole 90. Preferably the bolt is turned through an angle of 90". The nut 84 is then turned such that the washer 82 is urged against the lower face of the gusset plate 70. This urges the wing portions 80 of the bolt against the upper face of the gusset plate 68 thereby placing the bolt in tension and preventing further rotational movement of it.

This is done with the gusset plates and quick release bolts at each corner of the adjacent tower sections thus rigidly fixing them together.

The inner edge of the gusset plate 70 has a locating device which can be seen in cross section in figure 7. This comprises an upwardly extending portion 94 with a face 96 angled downwardly towards the upper surface of the gusset plate 70.

If an upper one of a pair of adjacent tower units is slightly off centre when lowered on the lower unit of the pair then at least one of the gusset plates 68 on that upper unit will contact the angled surface 96 of its respective co-operating gusset plate 70. The angle 96 will cause the gusset plate 68 and consequently the upper unit to be urged towards its correct position above the lower tower unit.

A perspective view of an intermediate unit of the tower can be seen in figure 8, with gusset plates 68 and 70 at the corners. The intermediate section includes a section of the ladder 26. This is supported on rails 98 and can be moved to a plurality of postions on these rails and then locked in place. This is in order to line it up with ladder sections in adjacent tower units.

The mounting arrangement for the ladder section on the rails 98 can be seen in more detail in figure 9. The rails 98 are formed from scaffolding sized tubes which correspond to those used for other horizontal and vertical members in the tower unit. The ladder section comprises a pair of angled side portions 100 which retain steps 102 of the ladder between them. A pair of hand rails 104 are spaced from the side portions 100 on the side on which the ladder is to be climbed.

The side portions 100 and the hand rails 104 are fixed by welding to upper and lower channels 106 which locate over the rails 98 with their open faces away from the ladder. These channels contain low friction pads 108 to enable the channel section, to move freely on the rails 98. These pads may be formed from plastics material such as PTFE.

The upper rail 98 has a series of holes 110 in its lower side. The upper channel member 106 has a hole 112 in its lower face located so as to align with the holes 110, in series, as the channel member is slid along the rail. A tube 114 is fixed over the hole 112.

This retains a pin 116 carrying a flange 118 which prevents the pin passing completely through the hole 112. A spring 120 is trapped between the flange 118 and a closure member 122 at the lower end of the tube 114. This closure member 122 has a central hole through which the end of the pin 116 passes.

In the position shown in figure 9 the spring is urging the pin 116 upwardly through the hole 112 and through a hole 110 in the rail 98 with which the hole 112 is aligned. Thus the ladder section is locked in this position by the action of the spring and the pin locating in the holes.

In order to unlock the ladder section the pin 116 is pulled downwardly so that it disengages from hole 110 thereby enabling the ladder section to slide transversely by means of the channels 106 and the pads 108.

A corresponding locking arrangement is provided on the rail and channel on the other side of the ladder section. The two pins 116 are coupled together by a bar 124 which can be pushed downwards to disengage both pins at the same time thereby unlocking the whole ladder section so that it can be moved to a desired location.

By using this arrangement of transversely slidable ladder sections a tower can be constructed using different combinations of base, top, and intermediate tower units and the ladder sections in each of the base and intermediate units transversely slid to form a straight ladder emerging at the arrival platform 28 on the top tower unit. Thus a tower of any desired height can be constructed with the intermediate units inserted in any order. In the example illustrated here the base unit is 2 metres high and the intermediate units are each 1 metre high. Preferably no units are provided which are in excess of 2 metres since this would.entail leaving the ground to secure the quick release bolts which join the tower units together. However, units of, for example i metre and 112 metres could be provided to give a greater range of tower sizes.

The tower can be provided in kit form with a top unit, a base unit, and several intermediate units.

A temporary structure such as a tower of the type described here can be used in many applications such as studio and theatre audience seating structures, camera mounting, stage platforms and rostrums, and any industrial or leisure applications requiring movable structures which can be quickly assembled, moved, and locked down in a desired position.

The locking castor described here is suitable for use as a locking device for a wide variety of portable wheeled objects.

Claims

1. A prefabricated stackable unit for use in the erection of a temporary structure comprising a stepped section movable between a plurality of positions and leading from a lower surface to an upper surface of the unit.

2. A prefabricated stackable unit according to claim 1 in which the stepped section is movable substantially transversely of the unit.

3. A prefabricated stackable unit according to claim 1 or 2 in which the stepped section is movable by means of tubular members slidably guided within channel members.

4. A prefabricated stackable unit according to claim 3 in which the tubular members comprise structural portions of the prefabricated unit.

5. A prefabricated stackable unit according to claim 3 or 4 in which the tubular members are substantially horizontal.

6. A prefabricated stackable unit according to claim 3, 4, or 5 in which the stepped section is secured to the channel members which slide on the tubular members.

7. A prefabricated stackable unit according to claim 3, 4, 5 or 6 in which the channel members contain low friction pads in contact with the tubular members.

8. A prefabricated stackable unit according to claim 7 in which the low friction pads comprise plastics material.

9. A prefabricated stackable unit according to any of claims 6 to 8 in which the stepped section is supported in the unit by four channel members slidably guided on tubular members.

10. A prefabricated stackable unit according to any preceding claim including means for locking the stepped section at a desired location.

11. A prefabricated stackable unit according to claim 10 in which the locking means is operable to lock the stepped section in any one of a-plurality of predetermined locations.

12. A prefabricated stackable unit according to any of claims 3 to 8, and claim 10 or 11 the locking means comprises a hole in a channel member, an array of holes along a tubular member on which the channel member slides and a pin insertable into the holes wherein the hole in the channel member may be aligned with a hole in the tubular member, and the pin inserted into the thus aligned holes.

13. A prefabricated stackable unit according to claim 12 including means for urging the pin through the holes.

14. A prefabricated stackable unit according to claim 13 in which the urging means comprises a resiliently flexible member.

15. A prefabricated stackable unit according to claim 12, 13 or 14 in which two channel members supporting the stepped section include the locking means, and a coupling member connects the pins of the locking means together whereby the pins can be disengaged from the holes by movement of the coupling member.

16. A prefabricated stackable unit for use in the section of a temporary structure substantially as herein described with reference to figures 1, 8, and 9 of the drawings.

17. A castor carried on a spigot and including a braking means movable from a disengaged position spaced from a surface on which the castor is positioned to an engaged position substantially in contact with the said surface.

18. A castor according to claim 17 in which the braking means includes a substantially annular braking surface which is substantially in contact with the surface on which the castor is positioned when the braking means is in the engaged position.

19. A castor according to claim 17 or 18 in which the braking means comprises a cup-shaped braking member movable on the spigot between the engaged and disengaged positions.

20. A castor according to claim 19 in which the cup-shaped braking member covers the castor in the engaged position.

21. A castor according to claim 19 or 20 in which the cup-shpaed braking member moves on the spigot between the engaged and disengaged positions by means of a threaded portion of the spigot engaged with a corresponding threaded portion of the braking member.

22. A castor carried on a spigot substantially as herein described with reference to figures 3 and 4 of the drawings.

23. A method for erecting a temporary structure from a plurality of stackable units comprising the steps of: a) attaching a lifting means to an uppermost unit, of the temporary structure; b) raising the uppermost unit onto a next uppermost unit with the lifting means; c) securing the two units together; d) raising the thus joined sections onto a further next uppermost unit with the lifting means; e) securing the further next uppermost unit to the said joined units; and f) repeating steps d) and e) until a desired number of units have been joined to form the structure.

24. A kit for erecting a temporary structure according to the method of claim 23 comprising a plurality of stackable units including a top unit, the top unit including means for attachment to a lifting means.

25. A kit according to claim 24 in which the attachment means comprises a pair of boots to receive the forks of a fork lift truck.

26. A temporary structure comprising a plurality of prefabricated stackable units, and a quick-release bolt for securing pairs of adjacent units in the structure to each other, the quick release bolt being retained in a recess in a first plate attached to a first unit of a pair and being insertable and lockable in a hole in a second plate of a second unit of the pair when the units are brought together.

27. A temporary structure according to claim 26 in which the quick release bolt carries a pair of abutments which locate in wing portions of the recess in the first plate and which pass through corresponding wing portions of the hole in the second plate prior to locking of the bolt.

28. A temporary structure according to claim 26 or 27 in which the first and second plates include co-operating locating means whereby the recess and hole in the plates are aligned when the units are brought together.

29. A temporary structure according to claim 28 in which the locating means comprises an edge portion of a first plate extending towards a second plate and including a surface angled towards the surface of the first plate whereby the second plate can slide on the angled surface as the units are brought together to align the hole and recess in the plates.

30. A temporary structure according to claim 28 or 29 in which each unit includes a first or a second plate and an associated locating means in each corner.

31. A temporary structure comprising a plurality of prefabricated units substantially as herein described with reference to figures 5, 6 and 7 of the drawings.