Abstract:
A self-supporting, readily erectable and transportable mast that includes a pneumatically inflatable elongate tubular member useful for providing structural support when raising various types of equipment above the ground. Included in the tubular member are woven or interwoven textile reinforcing strands arranged in one or more layers that may be laid at various angles useful for reinforcing and strengthening the tubular member when raised.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 12/812,946, filed Sep. 16, 2010, which is a national stage of PCT/GB2009/000112, filed Jan. 16, 2009, which claims foreign priority to Appl. No. GB 0819761.8, filed Oct. 28, 2008, and Appl No. GB 0800703.1, filed Jan. 16, 2008, all of which are hereby incorporated by reference in their entireties. 
    
    
     BACKGROUND 
     This disclosure relates to the temporary support of signs and of other equipment, such as electrical equipment, especially floodlights, above the ground. 
     There are numerous circumstances where signs or other equipment, especially electrical equipment of different kinds, needs temporarily to be mounted on a support above the ground. Examples include temporary traffic signs or signals, public address speakers at a country show or for a travelling circus, satellite dishes for military communication, emergency lighting for roadworks, and temporary floodlights for emergency workers at the site of an accident or for sporting fixtures played after dark or in poor lighting conditions, especially on public grounds. 
     While there have been numerous prior proposals for temporary supports for signs and for electrical and other equipment, mostly in the form of mechanically connectable structures, the structures proposed have often suffered from being too complicated to be readily erectable and demountable by a single person unfamiliar with the structure, too bulky when collapsed to be readily transportable, for example in the boot (trunk) of a small car (automobile), or insufficiently stable. 
     As will become clear from the detailed description below, the present disclosure adopts a different approach. 
     SUMMARY OF THE INVENTION 
     In accordance with a first aspect of this disclosure, equipment is adapted to be temporarily supported above the ground by a self-supporting, readily erectable and transportable mast, the mast comprising: a pneumatically inflatable elongate tube having a first end to which the equipment is coupled and a second end coupled to a ground support tripod, and being provided with bracing structure adapted to brace the tube when inflated and including respective flexible members extending from each tripod leg to the first end of the tube. 
     Preferably the tripod legs are extendable, preferably being telescopic, and are interconnected by bracing struts that may be pushed beyond dead centre to resist unintentional collapse. 
     It will readily be appreciated that a bracing structure formed of flexible members is non-rigid, and so allows the structure as a whole to be packed away for easy transport when not inflated. The principal rigid components of the structure will be the tripod, which, as noted above preferably has telescopic legs to reduce its packing space requirement, and the equipment to be supported. As will become clear from the detailed description below with reference to the accompanying drawings, this enables (say) a temporary floodlight to be transportable in a conventional shoulder bag for erection where required simply by opening the tripod and inflating the tube. 
     The flexible members may each comprise a single or multiple ply cord interconnecting each leg, preferably from a mounting point intermediate its ends when extended, to the first end of the tube, preferably with additional connections to one or more collars mounted on the tube at positions intermediate its ends. The additional connections may comprise respective cords extending from the collar to each said flexible elongate member. Alternatively, each such collar may be provided with three spokes, the proximal ends of which are coupled to the collar, and the distal ends of which are coupled to the cord. For each collar, the distal ends of its spokes are preferably connected by three further cords. 
     When the tube is inflated for use, the cords are each placed under tension, thereby bracing the structure as a whole. 
     In an alternative arrangement, each flexible member may comprise a respective web of material interconnecting a mounting point intermediate the ends of a leg when extended with the first end and the second end of the tube. 
     When the tube is inflated for use and the tripod positioned on the ground, each said web is placed under tension between the first end and the mounting point and between the first and second ends, thereby bracing the structure as a whole. 
     Preferably the tube is flexible when deflated and substantially inflexible when inflated, and includes reinforcing textile strands helically laid between two layers formed from a material selected from rubber, substitutes therefor and plastics, the strands being laid at an angle to the axis of the tubular member of 45°, and more preferably, 30° or less. 
     Preferred embodiments have one or more of the following features: The said material is PVC. The reinforcing strands are formed of a textile material, preferably nylon. The reinforcing strands are helically wound in opposing senses about the axis of the tubular member so as to cross. The reinforcing strands are laid at an angle of between 10 and 15°. The strands with opposing sense may be interwoven, thereby resulting in a woven textile reinforcing structure. There is a second layer of reinforcing strands laid at a different angle to the first. The first layer of reinforcing strands are laid at an angle of between 10 and 15° and the second layer of strands are laid at an angle of about 45°. There is a further layer of reinforcing strands extending parallel to the axis of the tubular member. 
     The term “equipment” as used herein is intended to encompass any form of mechanical or electrical equipment desired to be supported at a height above the ground, including flags, static signs, manually movable signs such as a manual Stop/Go board for controlling traffic flow at road works, sports equipment such as a netball goal or basketball net, and electrically operable equipment of diverse kinds, including, in particular, temporary floodlights flags, electrically operable signs, traffic signals, public address loudspeakers, illuminated road signs, beacons, security, safety or speed cameras, satellite dishes, and television cameras. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of equipment adapted for temporary support above the ground are hereinafter more particularly described by way of example only with reference to the accompanying drawings, in which: 
         FIG. 1  shows a bag for transporting equipment and mast, and also a hand operable pneumatic pump; 
         FIG. 2  shows the bag of  FIG. 1  opened to reveal the equipment, here a temporary floodlight; 
         FIG. 3  shows the equipment and mast removed from the bag and coupled to the pump for inflation of an elongate tube; 
         FIG. 4  shows the equipment supported by the erected mast; 
         FIG. 5  shows the equipment and one end of the tube on an enlarged scale; 
         FIG. 6  shows an alternative intermediate bracing structure coupled to a collar on the tube; 
         FIG. 7  is a view similar to  FIG. 4  with a bracing structure including a variation of the intermediate structures shown in  FIG. 6 ; 
         FIG. 8  shows the equipment and mast of  FIG. 7  collapsed ready for packing away in a bag; 
         FIG. 9  is a view similar to  FIG. 4  with an alternative web-based bracing structure; 
         FIG. 10  shows the structure of  FIG. 9  partially collapsed for packing away into its bag; 
         FIG. 11  shows the structure of  FIG. 9  in the course of being so packed away; 
         FIGS. 12 to 15  show different forms of equipment mounted to the first end of a tube in a structure as shown in  FIG. 9 ; 
         FIG. 16  shows a somewhat schematic and incomplete side elevational view of a tube with reinforcing strands wound at 45°; 
         FIG. 17  shows a similar side elevational view of a tube with reinforcing strands wound at 10°; 
         FIG. 18  shows a similar side elevational view of a tube with reinforcing strands wound as in both  FIG. 16  and  FIG. 17 ; 
         FIG. 19  is perspective view of a length of the tube of  FIG. 18  with the strands shown between two plastics layers, one shown partly cut away to show the strands; 
         FIG. 20  is a perspective view similar to  FIG. 19  for a tube with a further layer of reinforcing strands parallel to the axis of the tube. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     As will be apparent from  FIGS. 1 and 2 , electrical equipment, here a temporary floodlight  1 , and a mast for supporting the floodlight, as described in more detail hereinbelow, are readily transportable by a single person in a shoulder bag  2 , and need only a simple manually operable pump, here a stirrup pump  3 , for erection of the mast on site for temporary support of the electrical equipment above the ground. 
     A pneumatically inflatable elongate tube  4 , shown before inflation in  FIG. 3 , has a first end  5  coupled to the floodlight, as best shown in  FIGS. 2 and 5 , and a second end  6  coupled to a tripod  7 , which is shown with its legs  8  unfolded in  FIG. 3 , but before extending the legs. In this arrangement the legs are telescopic, comprising a first leg member  9 , the proximal end of which is pivoted at  10  to a tripod centre member  11  which is coupled to the second end  6  of the tube, and a second leg member  12  which is telescopically slidable within the first leg member  9  and clampable thereto when extended. The distal ends  13  of the first leg members are connected by struts  14  pivoted to ends  13  and also to a central member  15 . The interlinked struts can be pushed beyond dead centre to brace the tripod against unintentional collapse. 
     A valve  16  is provided for coupling to a pneumatic line  17  connected to pump  3 . An electrically operable pump, for example run from a cigar lighter socket in a car (automobile) may be used in place of a manually operable pump. Valve  16  is preferably placed near to the first end of tube  4  so that the mast may only be inflated or deflated when lying on the ground. This avoids the possible problem of electrical equipment falling on someone as the mast is deflated. 
     As can be seen from  FIGS. 2 and 5 , floodlight assembly  1  is mounted on a bracket  18  so as to be angularly adjustable, bracket  18  being mounted on a disc  19  closing the first end  5  of the tube. Electrical wiring  20  for the floodlight assembly  1  passes through an air-tight grommet  21  into the interior of tube  4  and exits at the second end  6  of the tube  4 , as best shown in  FIG. 3 , through a similar grommet (not shown). 
     Elongate flexible members, here in the form of guide lines  22  interconnect the distal ends of the first leg members with disc  19  at the first end  5  of the tube. When the tube  4  is adequately inflated ( FIG. 4 ), the guide lines  22  are placed under tension. Guide lines  22  may be formed from single or multiple ply cords. Additional bracing cooperating with the guide lines  22  may be provided as shown in  FIG. 4 . Tube  4  is shown mounting several collars  23  along its length. Here illustrated only for one such collar, elastic cords  24  are coupled between the guide lines  22  and the collar  23 . It will be understood that similar elastic cords may be provided for the other collars  23 . 
     An alternative intermediate bracing structure cooperating with guide lines  22  is shown in  FIG. 6 . In this embodiment, a collar  23  mounts three spokes  25 , the distal end of each spoke being coupled to a respective guide line  22 . The spoke distal ends are also preferably interconnected by cords  26 . 
       FIG. 7  shows an alternative embodiment of electrical equipment and supporting mast, employing additional bracing structures with spokes  25  as in  FIG. 6 , but without the additional cords  26 . As can be seen from  FIG. 8 , even structure such as that of  FIG. 7  will readily collapse for packing away for transport. 
     Tripod  7  may be provided with castors  27  so that the erected mast and equipment may be wheeled into position. The castors are preferably lockable. 
     Since the electrical equipment and mast may be packed away in a shoulder bag for ready transport, and may be erected on site simply by opening the tripod and inflating the tube, transport, erection and taking down can all be performed by a single person without any tools other than a simple pneumatic pump, and without any assembly or disassembly of mechanical parts. 
     Other arrangements are feasible. Thus, as illustrated in  FIGS. 9 to 11 , it is not necessary for the tube bracing structure to be provided by guide lines. Here respective flexible webs  28  interconnect mounting points  29  on the legs  8  with both the first  5  and second  6  ends of the tube. When the tube is inflated and erect on the tripod  7 , the respective webs  28  are in tension between their mounting point  29  and the first end and between the first and second ends. Flexible cords  30  are here shown interconnecting the mounting points  29 . We have found that the illustrated structure remains stable even in a moderate wind. To reduce any tendency for the webs  28  to act as sails, they may include apertures (not shown) to allow air to pass through the webs. The webs may be connected along their inner edges  31  adjacent the tube  4  to collars  23  spaced along the tube. 
     While the embodiments illustrated in  FIGS. 1 to 11  include electrical equipment in the form of a floodlight, persons of ordinary skill will readily appreciate that similar masts may be employed to mount other forms of equipment that it is desired to temporarily support above the ground, such as, without limitation, public address speakers, temporary traffic signals or illuminated road signs, security, safety or speed cameras, or communication equipment such as satellite dishes, or even equipment that is not electrical, such as, without limitation, basketball or netball nets, or signs that do not require illumination.  FIG. 12  shows a netball goal  32  mounted to a first end of a tube in a structure otherwise as shown in  FIG. 9 .  FIG. 13  shows a public address loudspeaker  33  mounted by a swivel bracket  34  to a first end of a tube in a structure otherwise as shown in  FIG. 9 .  FIG. 14  shows a close circuit television camera  35 , for example a security camera or a speed camera, coupled by an adjustable mount  36  to a first end of a tube in a structure otherwise as shown in  FIG. 9 .  FIG. 15  shows a static warning sign  37  mounted to a first end of a tube in a structure otherwise as shown in  FIG. 9 . 
     The elongate tube  4  may be formed from a similar material to that described in our co-pending British Patent Application No: 0501474.1 (published as GB 2422322 A) for use in providing inflatable sports goals. The material suggested in GB 2422322 for forming the tubular struts was natural or synthetic rubber, or plastics substitutes, preferably reinforced with nylon thread. Commercial embodiments of sports goals have since been produced and sold under our Registered Community Trademark Igoal®, and are formed with a thickness in the material of the struts of around 2 mm, and a diameter for the goalposts and cross-bar of 3 inches (7.62 cm), and work well when inflated with an applied pressure of around 1 Bar. The tubular members employ inner and outer layers of soft polyvinylchloride (PVC) with nylon threads between the two layers helically wound in opposing senses about the axis of the tube so as to cross, being laid typically with an angle to the axis of 80° or more. The two plastics layers are softened to fuse together in the interstices between the nylon threads. We have found that this structure prevents the tube from ballooning (expanding diametrically) in use. An additional layer of parallel threads preferably runs along the length of the tubular member to prevent stretching lengthwise in use. 
     Elongate tubes formed in the same way work well with the structures described in the present Specification. However, as explained below, and as described and illustrated in our co-pending patent application No: 0819761.8 (not yet published at the date of filing of the present Application), we have found that improved results can be achieved with alternative tubular structures. 
     In  FIG. 16 , tube  4  comprises a layer  38  of plastics, suitably a relatively soft plastics material such as PVC, or rubber, overlaid with reinforcing strands  39 . The strands  39  comprise a textile material, preferably nylon. In  FIG. 16 , the strands  39  are wound helically about layer  38  in opposing senses at an angle of 45° to the axis of the tubular member. The opposing sense strands may be interwoven, forming a woven textile reinforcing structure  40 . 
     In  FIG. 17 , similar reinforcing strands  41  are laid at an angle of 10°, again in opposing senses, the opposing sense strands being interwoven, thereby resulting in a woven textile reinforcing structure  42 . Our experiments have shown that a tube  4  as illustrated in  FIG. 17  would be substantially more rigid when inflated to the same operating pressure than a structure as shown in  FIG. 16 , which is already an improvement on the structure described in GB 2422322 and that a significantly improved rigidity can already be detected at an angle reduced from the 45° angle of  FIG. 17  to about 30°. 
       FIGS. 18 and 19  show a preferred structure with two superposed reinforcing layers comprising the woven textile reinforcing structures  40  and  42 . 
     It will be understood that in each of  FIGS. 16 to 19 , the reinforcing structures are shown incomplete for the purpose of illustration and explanation, and that in practice the reinforcing structures would extend along the entire length of the tube  4 . 
     As best shown in  FIG. 19 , a second layer  43  of plastics, suitably a relatively soft plastics material such as PVC, or rubber overlies the reinforcing structures. As can be seen from the drawings, the textile strands are spaced so that, even with two superposed reinforcing structures, as in  FIGS. 18 and 19 , there are interstices between the strands. During application of the second layer  43 , or subsequently thereto, the two layers  38  and  42  are warmed sufficiently to fuse together through the interstices of the reinforcing layers. 
       FIG. 20  shows a variation on the structure of  FIGS. 18 and 19 , in which a further layer of reinforcing strands  44  is employed, the strands, in this case, extending parallel to the axis of the tubular member. These strands help to prevent the tube  4  stretching lengthwise. 
     For most purposes contemplated by the present invention, we find that a tube  4 , as shown in  FIGS. 18 and 19  or in  FIG. 20 , having a diameter of 3 inches (7.62 cm) when inflated to a typical inflation pressure of around 1 Bar, namely between 10 and 20 psi (6.89 to 13.79*10 4  pascals), realisable with a foot pump or with an inexpensive tyre pressure pump operating from the cigar lighter socket of a vehicle, and an overall thickness of 2 mm, works well. The textile strands are preferably in the form of thin textile thread. The textile thread may comprise conventional nylon sewing thread. It will be understood, however, that different diameters and thicknesses may be chosen. The tube  4  when deflated is readily flexible, allowing the temporary structure to be packed away and to be portable. 
     The adoption of tubes  4 , especially as shown in  FIGS. 18 and 19 , which possess enhanced rigidity when inflated, raises the prospect of providing masts for equipment to be mounted aloft as described above, where the mast is significantly taller than heretofore, or where the bracing structure is reduced