1 AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION STANDARD PATENT "Clamp with Adjustable Support" The following statement is a full description of this invention, including the best method of performing it known to me: 2 Clamp with Adjustable Support 5 Background and Summary of the Invention This invention concerns the use of clamping devices and is particularly adapted to the use of such clamping devices on building sites for affixing temporary safety railing at elevated positions. 10 There is an increasing emphasis on the provision of safety railing on building sites to prevent accidental falling of personnel from dangerous heights. Sometimes such railing can be readily fastened into position by known techniques. But often the structure of a building, the state of erection, or the nature of work yet to be done means that it is difficult 15 to support satisfactory safety railing without unduly restricting access to the parts of the building under construction. Often it has proven necessary to custom manufacture components for particular sites and/or remove roofing or damage plasterwork in order to satisfactorily affix suitable railing. A particular problem arises where it is desired to support railing from beneath a rafter because the roofing material is already in place. This 20 is especially difficult in the case of sloping rafters because such slopes vary from building to building and even within given buildings and it is inconvenient and expensive to carry specifically angled systems to suit all the possible slopes. An aim of one form of the present invention is to provide a device which overcomes or 25 reduces at least some of these difficulties. The device is adjustable on site for use with roofs of any slope. An aim of another form of the invention is to provide a method of attaching a safety railing which reduces the range of hardware required for jobs involving many different modes of 30 attachment.
3 Accordingly, in one aspect the invention provides a device for securing a support post for a temporary safety rail attached to a frame member of a building, said device comprising: - a clamp portion adapted to clamp to the frame member, - a post attachment portion adapted to be releasably attached to the support post, 5 - a rotatably adjustable connection to adjust the angular relationship between the clamp portion and the post attachment portion, - a first array of teeth carried on the post attachment portion, - a second array of teeth carried on the clamp portion, - the first array being engaged with the second array to prevent rotational movement 10 between the post attachment portion and the clamp portion. The frame member may be a rafter, with said clamp portion comprising a pair of jaws actuatable towards and away from each other, a first of said jaws having a pair of arms, and said arms separated so said clamp portion may be positioned to clamp the rafter between 15 said jaws while an elongate member fastened to the rafter and at right angles to the rafter extends between said jaws. Preferably: - each said jaw has a working face mutually opposed to the working face of the 20 other jaw and which in use bears against said frame member, - said working faces each have a first end adjacent a mechanism for said actuation and a second end opposite said first end, said second ends defining an open end of the clamp, and - said working faces are angled towards each other from said first end to said 25 second end. Preferably said jaws each having a first end adjacent a mechanism for said actuation and a second end opposite said first end, said second ends of the jaws defining an open end of the clamp, and at said second ends each jaw has one or more spikes directed from said working 30 face towards the respective opposite jaw.
4 Preferably: - a shaft connects said jaws and is threadedly engaged with one of said jaws such that rotation of the shaft in a first direction causes the jaws to move towards each other and rotation of the shaft in a the opposite direction causes the jaws to move 5 away from each other, and - a driving head is formed on each end of the shaft whereby the shaft may be rotated by a tool engaged with either driving head. In a second aspect the invention provides a method of attaching a safety railing to a frame 10 of a building comprising: - providing a securing device having first and second portions rotatably adjustable relative to each other, and lockable at a plurality of predetermined angular positions relative to each other, said plurality of angular positions being spread over an arc of greater than 45", 15 - engaging said portions to lock said portions at one of said positions, - clamping said first portion to a frame member of the building, - attaching a first post to said second portion, - supporting a second post from said frame of the building, and - clamping rails to said posts to support the rails between said posts, 20 said method including the step of adjusting said angular positions such that said first post is held in a generally vertical orientation. The frame member of the building may be a vertically aligned elongate member and the first post clamped directly to said second portion. 25 The frame member of the building may be a horizontally extending member, a first end of a curved rigid elongate joining piece may be clamped to said second portion, and said first post clamped to the second end of the elongate joining piece. 30 The arrays of teeth are preferably circular or part-circular. The teeth are preferably pointed radially relative to the axis of said rotatable adjustability. The teeth in each array are 5 preferably aligned at an angle at a of 60 or 7%*? or 9* or 100 relative to their immediately neighboring teeth in the respective said array. One of said arrays of teeth may be formed around the perimeter of a circular first 5 component and the other of said arrays formed around the inside of a circular hole in a second component. In a third aspect the invention provides a method of attaching a safety railing to a frame of a building comprising: 10 - providing a securing device having first and second portions rotatably adjustable relative to each other, and lockable at a plurality of predetermined angular positions relative to each other, said plurality of angular positions being spread over an arc of greater than 450, - engaging said portions to lock said portions at one of said positions, is - clamping said first portion to a frame member of the building, - clamping a first end of an elongate joining piece to said second portion, - clamping a first post to the second end of said elongate joining piece, - supporting a second post from said frame of the building, and - clamping rails to said posts to support the rails between said posts, 20 said method including the step of adjusting said angular positions such that said first post is held in a generally vertical orientation. Preferably said plurality of angular positions is spread over an arc of at least 900, more preferably at least 180*, and more preferably over a full circle. 25 The first and second rotatably adjustable portions may engage to lock by means of interlocking arcuate or circular arrays of teeth. The teeth of one of said rotatably adjustable portions may extend radially outwardly from a 30 disc-shaped portion. The array of teeth of said one of the rotatably adjustable portions may extend for the full perimeter of the disc-shaped portion.
6 The teeth of one of said rotatably adjustable portions may extend radially inwardly at the perimeter of a hole in said one rotatably adjustable portion. The array of teeth of said one of the rotatably adjustable portions may extend for the full perimeter of said hole. 5 Preferably the teeth of a first of said rotatably adjustable portions extend radially outwardly from a disc-shaped portion and the teeth of the second of said rotatably adjustable portions extend radially inwardly at the perimeter of a hole in said one rotatably adjustable portion. When the safety railing is being attached to a rafter having an upwardly facing top face and 10 a downwardly facing bottom face, said attachment being in a region where a roof batten is fastened to said top face of the rafter, said method may comprise: - positioning adjacent the rafter said first portion comprising a clamp which has a pair ofjaws actuatable towards and away from each other; - positioning a first of said jaws against said top face of the rafter, said first jaw 15 comprising a pair of arms extending across said top face such that a gap between said arms extends across said top face and at least a portion of the batten extends across said rafter within said gap between the arms; - positioning the second of said jaws against the bottom face of the rafter; - tightening the clamp against said top and bottom faces to thereby fasten the 20 clamp to the rafter, and - attaching the safety railing to the clamp. The batten may comprises a metal section having a pair of downwardly extending legs defining a channel therebetween, one of the legs fastened between said arms to the rafter 25 and one of said arms extends into the channel where the batten crosses the rafter. Preferably one or more spikes are directed from its respective said working face towards the respective opposite jaw; and an actuating mechanism is activated to press the working faces towards each other to clamp tightly against the frame member whereby said spices 30 engage with the frame member to restrain the frame member from rotating in the clamp.
7 Preferably each jaw carries a plurality of spikes spaced along the jaw. Preferably said spike or spikes engage a side face of the frame member, said side face being at right angles to said working faces. Preferably said spike or spikes are pressed by said clamping to penetrate into the frame member. 5 In a fourth aspect the invention provides a clamp for attaching a temporary safety railing to a rafter of a frame of a building said clamp comprising a pair of jaws actuatable towards and away from each other, wherein a first of said jaws has a pair of arms, said arms being separated so said clamp may be positioned to clamp the rafter between said jaws while an 10 elongate member fastened to the rafter and at right angles to the rafter extends between said jaws. In a fifth aspect the invention provides a method of attaching a temporary safety railing to a rafter of a frame of a building, said rafter having an upwardly facing top face and a 15 downwardly facing bottom face, said attachment being in a region where a roof batten is fastened to said top face of the rafter, said method comprising: - positioning adjacent the rafter a clamp which has a pair of jaws actuatable towards and away from each other; - positioning a first of said jaws against said top face of the rafter, said first jaw 20 comprising a pair of arms extending across said top face such that a gap between said arms extends across said top face and at least a portion of the batten extends across said rafter within said gap between the arms; - positioning the second of said jaws against the bottom face of the rafter; - tightening the clamp against said top and bottom faces to thereby fasten the 25 clamp to the rafter; and - attaching the safety railing to the clamp. Said batten may comprise a metal section having a pair of downwardly extending legs defining a channel therebetween, one of the legs is fastened between said arms to the rafter 30 and one of said arms extends into the channel where the batten crosses the rafter.
8 In a sixth aspect the invention provides a clamp for fastening components to an elongate frame member of a building, said clamp comprising a pair of jaws actuatable towards and away from each other, each said jaw having a working face mutually opposed to the working face of the other jaw and which in use bears against the frame member, said 5 working faces each having a first end adjacent a mechanism for said actuation and a second end opposite said first end, said second ends defining an open end of the clamp, wherein said working faces are angled towards each other from said first end to said second end. In a seventh aspect the invention provides a clamp for fastening components to an elongate 10 frame member of a building, said clamp comprising a pair of jaws actuatable towards and away from each other, each said jaw having a working face mutually opposed to the working face of the respective other jaw and which in use bears against the frame member, said jaws each having a first end adjacent a mechanism for said actuation and a second end opposite said first end, said second ends defining an open end of the clamp, wherein at said 15 second ends each jaw has one or more spikes directed from said working face towards the respective opposite jaw. In an eighth aspect the invention provides a method of attaching a component to an elongate frame member of a building, said method comprising: 20 - engaging with the frame member a clamp comprising a pair of jaws actuatable towards and away from each other, each said jaw having: - a working face mutually opposed to the working face of the respective other jaw and which in use bears against the frame member; and - one or more spikes directed from its respective said working face towards 25 the respective opposite jaw; and - activating an actuating mechanism to press the working faces towards each other to clamp tightly against the frame member whereby said spikes engage with the frame member to restrain the frame member from rotating in the clamp. 30 In a ninth aspect the invention provides a clamp for fastening components to an elongate frame member of a building, said clamp comprising a pair of jaws actuatable towards and away from each other, a shaft connecting said jaws and threadedly engaged with one of 9 said jaws such that rotation of the shaft in a first direction causes the jaws to move towards each other and rotation of the shaft in a the opposite direction causes the jaws to move away from each other, wherein a driving head is formed on each end of the shaft whereby the shaft may be rotated by a tool engaged with either driving head. 5 In a tenth aspect the invention provides a clamp for attaching a temporary safety railing to a rafter of a building said clamp comprising: - a pair of jaws actuatable towards and away from each other, - a first of said jaws having a pair of arms extending sideways relative to the 10 direction of said actuation, - each arm carrying a faceplate for said first jaw, said faceplates extending away from each other and outwards from their respective said arm, but not extending towards each other from said respective arms. 15 Brief Description of the Drawings In order that the invention may be more fully understood there will now be described, by way of example only, preferred embodiments and other elements of the invention with reference to the accompanying drawings where: 20 Figure 1 is an exploded view of a device according to one embodiment of the present invention; Figure 2 is a rear view of one of the components in Figure 1; Figure 3 is a partially cross-sectioned plan view looking down upon the device in Figure 1 when being used in a first configuration; 25 Figure 4 is an elevation view of a safety railing assembly incorporating the device illustrated in Figure 1 when attached in a second configuration to a frame of a building; Figure 5 is an elevation view of an alternative safety railing assembly wherein the device in Figure 1 is attached in a third configuration to a frame member of a 30 building; 10 Figure 6 is a side view showing a third example of a safety railing assembly wherein the securing device of Figure 1 is being used in a fourth configuration to secure the assembly to a sloping rafter of a building frame; and Figure 7 is an enlargement showing the circled portion of Figure 6. 5 Description of Examples of the Invention and the Preferred Embodiment As seen in Figures 1 to 4, the securing device 10 consists of a clamp portion 12, a post attachment portion 14, a pressure plate 16, washer 18 and nut 20. All the components are 10 made of steel and galvanised. The device 10 is used to support a post 28 which in turn is clamped to three rails 100. A connector 27 is used between the device 10 and the post 28. The rails 100 are spaced vertically in accordance with government regulations. The rails 100 are also supported 15 elsewhere by other such posts and together form a safety railing assembly. The post attachment portion 14 comprises a clamping socket 22 welded to an arm portion 24. The clamping socket 22 is made from a length of square hollow section steel tube to which is welded a threaded nut 26 aligned with a hole in the tube so that a suitably slightly 20 smaller sized square section steel tube may be slid into the socket 22 and clamped at a chosen height by means of an L-shaped hand screw 30 engaged with the nut 26 and extending through the wall of the tube of clamping socket 22. The aim portion 24 has a central plate portion 32 with a pair of flanges 34 and 36 on 25 respective sides thereof all extending at right angles from the clamping socket 22. The central plate portion 32 extends beyond the flanges 34 and 36 in a semi-circular protrusion 38. The central plate portion 32 has a circular hole 40 therethrough, the perimeter of which carries a continuous array of teeth 42. The hole 40 extends for about half its diameter beyond the flanges 34 and 36 into the protrusion 38. 30 The clamp portion 12 has a fixed jaw portion 46 and a moveable jaw portion 48. The moveable jaw portion 48 has a base 50 formed from a short length of square hollow section 11 tube and a bearing end portion 49 rigidly attached thereto. The base 50 is inserted as a sliding fit into a corresponding square hollow section base 54 of the fixed jaw portion 46. The fixed jaw portion 46 has a bearing end portion 47 and a coupling portion 68 each rigidly attached to the base 54. 5 The respective outer ends 51 and 55 of bases 50 and 54 are blanked off. A threaded shaft 58 extends axially through the bases 50 and 54, through a plain hole 52 in the end 51 and threadedly engages with a nut 60 welded to the end 55. The threaded shaft 58 has a hexagonal head 62 and 64 rigidly attached at each end and an associated washer 63 and 65 10 between the respective head and end. By turning either one of the heads 62, 64 the bearing end portions 47 and 49 of respective jaw portions 46 and 48 are pulled towards each other or allowed to separate. The coupling portion 68 of the jaw portion 46 comprises a circular backing plate 70, a 15 toothed circular plate 72 and a threaded shaft 74 all extending coaxially with each other and at right angles to the shaft 58 such that the plate 72 extends from the backing plate 70 and the shaft 74 extends from the plate 72. The backing plate 70, toothed plate 72 and threaded shaft 74 are all rigidly affixed to each other and to the base 54 of the fixed jaw portion 46. The circular plate 72 carries a continuous array of teeth 76 extending radially 20 outwards therefrom. In use these mate with the teeth 42 on the post attachment portion 14. Both the plate 72 and the hole 40 in the embodiment illustrated have 36 teeth. So each tooth is aligned at an angle of 10" relative to their immediately neighbouring teeth. In alternative embodiments, 40, 48 or 60 teeth may be used for example and these would 25 correspond to tooth spacings of 9', 7%* and 6* respectively. In use the toothed circular plate 72 is mated with the toothed hole 40 with the clamp portion 12 and post attachment portion 14 aligned as desired, the pressure plate 16 and washer 18 fed onto the shaft 74 and nut 20 tightened onto the shaft. The pressure plate 16 30 has a flange 17 on its rim which bears onto the central plate portion 32 surrounding the hole 40. The thickness of the plate 72 and the central plate portion 32 are nominally the same and the flange ensures that if, due to manufacturing tolerances,. the plate 72 is in fact 12 slightly thicker than the central plate portion 32, the pressure plate 16 still bears tightly onto the central plate portion 32. The flange 17 may be an integral part of the metal of the pressure plate 16, but is preferably formed by adhering a ring of any appropriate material to the face of the pressure plate. 5 The bearing end portion 49 of the moveable jaw portion 48 is bifurcated. It has a pair of arms 78 which extend sideways relative to the shaft 58 and also extend in the direction of the shaft 58 to beyond the head 62. A pair of face plates 80 extend outwards from respective arms 78. A side plate 82 extends at almost right angles to the face plates 80 and 10 adjacent the base 50. The arms 78 each cary a terminal tooth which forms a spike 79 pointing towards the opposite jaw portion. The bearing end portion 53 of the fixed jaw portion 46 is less extensively bifurcated than that of the moveable jaw portion. A pair of arms 84 extend sideways relative to the shaft 15 58 but do not extend in the direction of the shaft 58 beyond the head 64. A face plates 86 is affixed to the arms 84. A side plate 88 extends at almost right angles to the face plate 86. Side plates 82 and 88 are coplanar. The arms 84 each carry a terminal tooth which forms a spike 85 pointing towards the opposite jaw portion. 20 As seen in Figure 3, the device 10 may be attached to a frame member 90 by rotating either one of the heads 62, 64 to tighten the face plates 80 and 86 against the frame member. The spikes 79 and 85 assist in preventing the clamp portion twisting on the frame member 90 by either wrapping around the member, as shown in Figure 3, or by biting into the material of thicker members. The frame members may be timber or steel. 25 The face plates 80 and 86 are aligned 30 from being at right angles to the axis of the shaft 58. The face plates therefore taper towards each other in the direction of their respective arms with an included taper angle of 6". As shown in Figure 3, the clamp has been tightened on the timber frame member 90 only enough for the face plates 80 and 86 to start 30 engaging the outer comers 130 and 132 of the timber. In use the clamp would be tightened further, causing some distortion of the timber, so the face plates would more firmly clamp against the engaging faces 134 and 136 of the timber. The taper between the faces causes 13 localised and uneven distortion of the timber and thus reduces the likelihood of the timber moving in the clamp. The solid clamping action provided by the invention provides a substantial advantage over prior art systems which merely wrap around and/or are nailed to a frame member they are attaching to. 5 The faceplates 80 and 86 extend about 37mm from the side plate 82, 88 to spikes 79, 85. This allows a 35mm thick stud to be accommodated as shown in Figure 3. For thicker timber the spikes 79 and 85 bite into the timber and the timber faces are still engaged by the faceplates 80 and 86. If, instead of the spikes 79 and 85, a lip was formed to extend 10 along the ends of jaw portions 46 and 48, the result would be much less satisfactory because the lip would not dig into the timber as far as the spikes would. It can be seen that, unlike some prior art brackets used to fasten to rafters, the jaws of the clamp do not need to wrap over the comers 130 and 132 and engage the side face 138 of the timber frame member 90 in order to tightly hold the timber. 15 The clamp portion is sized so that it can clamp to members from 65mm to 110mm. The device 10 can be readily clamped to wall studs which are very close to brickwork, or even hard up agaist brickwork by using the biting-in characteristics of the spikes 79 and 85. 20 A notch 39 is formed on the central extreme tip of the semi-circular protrusion 38. Notches 66a, 66b, 67a, 67b and 71a-l are also formed on the perimeter of the backing plate 70. The notches 66a and 66b are 1800 apart and aligned with the direction of shaft 58. The notches 67a and 67b are 1800 apart and aligned with the faceplate 86, so they are aligned at 25 90* to notches 66a and 66b. The twelve notches 71a to 711 are spaced 100 apart with three on each side of each of notches 66a and 66b. The diameter of the semi-circular protrusion 38 and the backing plate 70 are the same, so the notch 39 may be conveniently aligned with a designated notch on the backing plate to set the desired angular alignment between the clamp portion 12 and post attachment portion 14. 30 The device 10 is shown in a first angular configuration in Figure 3. In this configuration the notch 39 is aligned with notch 66a, which is closest to the moveable jaw 48, so the 14 securing device is extended linearly. This aligns the post attachment portion 14 in the same direction as the alignment of the frame member 90 and spaces the clamping socket 22 the greatest available distance from the frame member 90. 5 The clamping socket 22 is made from square section tube having the same cross-sectional dimensions as the main upright body 29 of the post 28. As seen in Figure 4, a short straight length of square section tube of a slightly smaller cross section is used as a connector 27 between the clamping socket and the post 28. The connector 27 is clamped at one end by the hand screw 30 and at the other end by a similarly configured hand screw 96 on the post 10 28. The height of the post may be adjusted by means of sliding and clamping the connector 27 as appropriate within the post 28 or the socket 22. A plurality of posts are erected in a spaced relationship and rails 100 for the safety railing fastened between them. Each post has rigidly attached clamps 98 whereby the rails 100 are attached. Any of many well known clamping systems may be used to attach the rails to the post. 15 As seen in Figure 4, the device 10 may be used to secure a post 28 to a vertical stud 92 in the frame of a building under construction. In the configuration shown, the notch 39 is aligned with notch 66b which is the most distant from the moveable jaw 48. Thus the clamp portion 12 and the post attachment portion 14 are aligned linearly, but are rotated 20 over upon each other. So, although (as in Figure 3) the clamping socket 22 is aligned in the same direction (vertically) as the stud 92, the clamping socket and stud are now spaced closer together than for the Figure 3 configuration. As either one of the heads 62, 64 may be turned to tighten the clamp, the clamp may be 25 easily tightened onto the stud from either inside or outside the building. This provides significant advantage when access from one side is restricted or dangerous. The device described above has a particularly useful application in that it is capable of supporting a safety railing by attachment from beneath a rafter. Figure 5 shows the device 30 10 being used to secure a post 28 to a horizontal rafter 94. In this configuration the notch 39 is aligned with notch 67a and the socket 22 is aligned at right angles to the rafter 94. The clamp portion may be tightened from above by turning head 62 or from below by 15 turning head 64. A rattle gun fitted with a socket drive is particularly useful for tightening and loosening the clamp. The device 10 has an especially useful application in that it may be used to support 5 generally vertically aligned posts of a safety railing when attached from the underside of sloping rafters of a building during construction. An example of an embodiment of the invention in this regard is shown in Figures 6 and 7. In Figures 6 and 7 the rafter 102 is aligned at 30* to the horizontal and extends out beyond 10 the wall (not shown) of the building. The notch 39 on the post attachment portion is aligned with notch 711 on the clamp portion before the nut 20 is tightened. The clamp portion 12 is thereby aligned at an angle of 300 to the post attachment portion, in contrast to the linear alignment of Figure 3. The clamp portion 12 is clamped to the sloping rafter 102 near the rafter's lower end, so that the clamping socket 22 is axially aligned 15 horizontally below the lowest line of the cave 106 of the building. A bent connector 127 is used to connect the post 28 to the socket 22. While the connectors 27 described in relation to above described embodiments were straight, the connector 127 is bent in a curve at right angles. Bent connector 127 is formed from the same tube stock as that used for connector 27 so its ends slide neatly into the bottom of the post 28 and socket 22 for clamping by the 20 L-screws 96 and 30 respectively. The height of the post 28 can be adjusted by loosening screw 96, and the spacing of the post from the eave 106 adjusted by use of screw 30. An advantage of the above-described bifurcation in the moveable jaw portion 48 can be seen in particular in the enlargement shown in Figure 7. The building frame 107 has a top 25 hat section steel batten 108 affixed to the upper surface of the rafter 102 at the place where it is desired to clamp the securing device 10. Corrugated steel sheets 114 are affixed to the batten 108. The cross section of such battens has a trough-like centre portion 110, a pair of upstanding walls 111, and a pair outwardly extending feet 112 at its bottom. The bifurcation of the jaw portion 48 allows the arms 78 to be positioned one on each side of a 30 foot 112 with one of the arms 78 and its associated face plate 80 extending into the trough 110 where it hooks over the top of the rafter 102. If the arm 78 and face plate 80 could not 16 extend into the trough 110, there would need to be a much longer horizontal component of the bent connector 127 which would cause undesirable flex in the safety railing structure. The embodiment of the securing device illustrated in Figure 1 has its teeth 42 and 76 at 100 5 alignments. Its use means that whatever the angle of a sloping rafter, the post 28 can be aligned within 5* of vertical. It is normally preferred for safety railing to not be inwardly sloping, in order to provide optimum access to the edge of the roof, and it is generally accepted that the upright posts of a safety railing system can lean up to 15* outwards from the building. 10 As best seen in Figure 1, the edges 87 of the faceplate 86 are positioned further outwards than the corresponding edges 89 of the side plate 88 when measuring in the direction of the length of the elongate frame member 90. Likewise the edges 81 of the faceplates 80 are positioned further outwards than the corresponding edges 83 of the side plates 82. This 15 means that if the clamp portion 12 is clamped to a vertical timber wall stud at the top or bottom of the stud adjacent a horizontal top plate or bottom plate, the edges 83 and 88 can be pressed to abut the top plate or bottom plate and the faceplates 80 and 86 would then overlap onto the top plate or bottom plate. Portion of the top plate or bottom plate, and the joint face between it and the stud, would therefore be captured between the faces 80 and 86 20 and thus within the clamping action. The strength of the safety railing would then not be as dependent on the strength of a possibly insecurely nailed joint between the stud and top plate or bottom plate. It will be appreciated that identical securing devices of the type described can be adjusted 25 into different configurations for many different applications. This means that construction of a safety railing system on a building site can be readily customised using a relative small variety of components, so reducing the inventory required to be carried to a site. Whilst the above description includes the preferred embodiments of the invention, it is to 30 be understood that many variations, alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the essential features or the spirit or ambit of the invention.
17 It will be also understood that where the word "comprise", and variations such as "comprises" and "comprising", are used in this specification, unless the context requires otherwise such use is intended to imply the inclusion of a stated feature or features but is 5 not to be taken as excluding the presence of other feature or features. The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that such prior art forms part of the common general knowledge in Australia. 10