AU2021204989A1 - Improvements Relating to Barriers and Barrier Supports - Google Patents

Abstract

A security fence assembly extending upwards from a wall at a building site. The fence assembly comprises an array of upstanding fence panels supported by a plurality 5 of clamp assemblies. Each fence panel comprises two vertical posts, each clamp assembly is clamped across the top of the wall, and each clamp assembly comprises a pair of jaw portions moveable towards and away from each other in a first direction transverse to the wall. The jaw portions of each clamp include an upstanding engagement means engaged with a respective said post to thereby retain and support 10 that post in an upright position.

Description

AUSTRALIA

PATENTS ACT 1990

COMPLETE SPECIFICATION

for the invention entitled:

"Improvements Relating to Barriers and Barrier Supports"

The following statement is a full description of this invention, including the best method of performing it known to me:

Improvements Relating to Barriers and Barrier Supports

Background and Summary of the Invention

5 This invention concerns the use of supports for temporary security fencing where it extends along the top of a wall which may be a retaining wall or a low wall forming a fence.

Security fencing is almost universally used around building sites in suburban areas. Where existing permanent fencing is insufficient, temporary fences are installed. A common form of such temporary fencing uses fence panels having end posts which protrude downwards to be held within vertical holes in weighted blocks. The panels once positioned are then fastened together end to end.

A difficulty arises when an excavated area on a building site extends to, or almost to, the boundary of the property concerned, leaving no room for the security fence to be erected. A similar situation arises where it is desired to position a temporary fence where there is already a low wall such as a brick fence. In such situations it would be desirable to have a means for conveniently fastening the temporary fence directly to the top of the retaining wall at the edge of the excavation, or to the top of the low brick fence.

The fastening means should ideally be usable on both masonry walls and on timber walls.

An aim of the present invention is to provide a fence assembly and components therefor which overcome or at least reduce these difficulties.

Accordingly in one aspect the present invention provides a clamp assembly adapted to clamp across the top of a wall in order to provide a support for two panels of a temporary fence, said clamp assembly comprising a pair of jaw portions adapted to move towards and away from each other in a first direction, said jaw portions including an engagement means adapted to engage with a post on said panels to thereby retain said post in an upright position.

Preferably said engagement means is adapted to engage said post in a sliding fit.

Preferably said jaw portions include a pair of said engagement means aligned with their longitudinal axes at right angles to said first direction, each said engagement means being adapted to engage in a sliding fit with a respective post on said panels to thereby retain said respective post in an upright position.

Preferably said pair of jaw portions are slidably engaged with a threaded shaft, and a nut is threadedly engaged with said shaft whereby tightening said nut causes said jaw portions to be urged towards each other in said first direction.

One of said jaw portions may include both of said engagement means. Said engagement means may be oriented in a line at right angles to the longitudinal axis of said shaft. Alternatively said engagement means may be oriented in a line parallel to the longitudinal axis of said shaft.

Each of said engagement means may be a tubular socket adapted to in use receive therein its said respective post. The socket preferably has a rectangular hollow cross section transverse to the socket's longitudinal axis. Alternatively each said engagement means may be an elongate stud adapted to slide in use into the lower end of its said respective post.

A said jaw portion may include a further and smaller engagement means extending parallel to said pair of engagement means and adapted to engage in a sliding fit with an end of a post of a fallguard handrail assembly.

In another aspect the invention provides a clamp assembly adapted to clamp across the top of a wall in order to provide a support for two panels of a temporary fence, said clamp assembly comprising:

- a pair ofjaw portions slidably engaged with a threaded shaft, - a nut threadedly engaged with said shaft whereby tightening said nut causes said jaw portions to be urged towards each other, and - said jaw portions including a pair of engagement means aligned with their 5 longitudinal axes at right angles to said shaft, each said engagement means being adapted to engage with a respective post on said panels to thereby retain said respective post.

Preferably each said engagement means is adapted to engage said respective post in a sliding fit.

Preferably one of said jaw portions includes both of said engagement means.

The engagement means may be oriented in a line at right angles to the longitudinal axis of said shaft. Alternatively the engagement means are oriented in a line parallel to the longitudinal axis of said shaft.

Each said engagement means may be a tubular socket adapted to in use receive therein its said respective post. Such a socket preferably has a rectangular hollow cross section transverse to the socket's longitudinal axis. Alternatively each said engagement means may be an elongate stud adapted to slide in use into the lower end of its said respective post.

Preferably said jaw portion includes a further and smaller engagement means extending parallel to said pair of engagement means and adapted to engage in a sliding fit with an end of a post of a falguard handrail assembly.

Preferably said shaft is threaded along its entire length, two nuts are threadedly engaged with said shaft, and said jaw portions are captive on the shaft between said nuts. Alternatively said shaft may have an enlarged head on one end and said jaw portions are captive on the shaft between said head and said nut.

The nut or nuts may have wings whereby said nut or nuts may be tightened without tools by using two hands.

Preferably each of said jaw portions comprises a main body portion having a hollow 5 tubular portion through which said shaft passes and a hollow clamping portion which bears onto a respective side of the wall. Preferably said main body portion is thin walled, Preferably said hollow clamping portion has flat walls the edges of which protrude as teeth for engagement with a surface to which said clamp assembly is being clamped,

Preferably each said main body portion has a V-shaped internal wall extending from one side of said main body portion to the other side of said main body portion and said shaft passes along the valley formed by the V-shape.

Preferably a first of said jaw portions has a said engagement means upstanding from a plate positioned alongside said shaft and said plate protrudes out towards the second said jaw portion. Preferably both of said engagement means are upstanding from said plate alongside said shaft. Both of said engagement means may be upstanding on the same side of said shaft Alternatively the shaft may extend between said engagement means.

In another aspect the invention provides a security fence assembly for a building site, said fence assembly extending upwards from a wall and comprising an array of upstanding fence panels supported by a plurality of clamp assemblies, wherein: - each said fence panel comprises two vertical posts, - each said clamp assembly is clamped across the top of said wall, - each said clamp assembly comprises a pair of jaw portions moveable towards and away from each other in a first direction transverse to the wall, - said jaw portions of each clamp include an upstanding engagement means engaged with a respective said post to thereby retain and support said respective post in an upright position.

Preferably said upstanding engagement means is engaged in a sliding fit with said respective said post to thereby retain and support said respective post in an upright position.

Each said post may be retained and supported in a vertical position by a separate said clamp assembly.

A said engagement means may engage with a first said post of a first said fence panel while a second said post of an adjacent panel is fastened directly to said first post and not engaged with any said upstanding engagement means.

In another aspect the invention provides a security fence assembly for a building site, said fence assembly extending upwards from a wall and comprising an array of upstanding fence panels supported by a plurality of clamp assemblies, wherein: - each said clamp assembly is as defined above, - each said fence panel comprises two vertical posts the bottoms of which engage with upstanding said engagement means, and - each said clamp assembly engages with posts of two of said fence panels.

Preferably said engagement means and said vertical posts are horizontally offset from the top of the wall. Preferably a first of said jaw portions includes both ofsaid engagement means.

The engagement means on each said clamp assembly may be different distances from the wall, Each said clamp assembly may be clamped with a threaded shaft extending across the top of said wall and, at each clamp assembly, said engagement means may be side by side in a line parallel to the longitudinal axis of said shaft. The respective planes of adjacent said fence panels may be offset relative to each other.

Alternatively the engagement means on each said clamp assembly may be the same distance from the wall. Each said clamp assembly may be clamped with athreaded shaft extending across the top of said wall and, at each clamp assembly, the engagement means may be oriented in a line at right angles to the longitudinal axis of said shaft The respective planes of adjacent said fence panels may be in line with each other. 5

Preferably at least one of said jaw portions incudes a plate member which extends to lay on the top of said wall underneath the threaded shaft and thus prevent the shaft from contacting the top of the wall.

Preferably each said post bears onto a plate which lies beneath said engagement means and said plate bears upon the top face of said wall.

The wall may be a masonry retaining wall, a brick fence or a timber wall.

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: Figure 1 is a view of a security fence assembly mounted along the top of a retaining wall according to a first embodiment of the present invention; Figure 2 is an enlarged view of portion of the fence assembly in Figure 1, particularly showing a support comprising a clamp assembly according to a second embodiment of the present invention when seen from the downhill side of the wall; Figure 3 is a view of the portion of the fence assembly in Figure 2 when seen from the uphill side of the wall; Figure 4 is a side view of the assembly in Figure 2; Figure 5 is a view of a security fence assembly mounted along the top of a retaining wall according to a third embodiment of the present invention; Figure 6 is an enlarged view of portion of the fence assembly in Figure 5, particularly showing a support comprising a clamp assembly according to a fourth embodiment of the present invention when seen from the downhill side of the wall; Figure 7 is a view of the portion of the fence assembly in Figure 6 when seen from the uphill side of the wall; 5 Figure 8 is a side view of the assembly in Figure 6; Figure 9 is a view of a portion of a fence assembly according to a fifth embodiment of the present invention; and Figure 10 is a side view of the assembly in Figure 9.

The reference numerals assigned to the features of the embodiment shown in Figures 5 to 8 are exactly 100 greater than the equivalent features of the embodiments shown in Figures 1 to 4. Similarly the reference numerals assigned to the features of the embodiments shown in Figures 9 and 10 are exactly 200 greater than the equivalent features of the embodiments shown in Figures 1 to 4

Description of Examples of the Invention including the Preferred Embodiment

The security fence assembly 10 shown in Figure 1 extends forpart of its length along the top portion 11 of a retaining wall 12 bordering an excavated area 13 of a building site. In practice the fence assembly shown would be part of a perimeter fence around a building site but the remainder of the perimeter fence is not shown.

The fence assembly as shown has four identical fence panels 14, the middle two 15 of which are entirely supported from three supports 17 comprising clamp assemblies 18 which are clamped across the top I Iof the retaining wall 12. The end fence panels 16 each have one end supported by a clamp assembly 18 and the other end supported by a conventional concrete-filled support block 27.

Each fence panel 14 has a perimeter frame 20 of circular cross-section tubular steel comprising an upper rail 21, a lower rail 22 and two vertical posts 23 and 24. The rails and posts are welded together using a bracing insert 25 at each corner of the frame 20. A welded steel mesh sheet 26 is welded to the frame to fill in the panel 14.

Each post 23 and 24 extends down below the lower rail 22 to form a post foot 31 which is engaged and retained by a respective clamp assembly 18. The panels 14 are oriented end to end in a continuous plane with a post 23 of one panel adjacent a post 24 of its adjoining panel. Adjacent posts are fastened together at their tops using conventional clamped fence panel joiners 29.

As seen more clearly in Figures 2 to 4, each clamp assembly 18 comprises a pair of jaw portions 28 and 30 independently neatly slidable along a steel shaft 32 which carries a thread 33 along its entire length. The jaw portions 28 and 30 are not internally threaded but are instead tightened onto the wall by means of a pair of winged nuts 34, one threaded onto each end of the shaft 32. The nuts 34 have a pair of diametrically opposed wings 35 which allow the nuts to be tightened by hand. The nuts and wings are sized such that two hands may be conveniently used to tighten or untighten a nut. The clamp assembly 18 therefore requires no tools to tighten it onto the wall.

The nuts 34 can be positioned anywhere along the length of the shaft 32 so the ends of the shall can protrude as preferred on each side of the wall.

The first jaw portion 28 has a main body portion 36 fabricated from sheet steel as a thin-walled structure which is hollow except for a V-shaped internal wall 37 which is further described below. The thin-walled box-like structure provides substantial strength at minimum weight.

The main body portion 36 has two flat sidewalls 44 and 45, a rear wall 46, a dual pitched upper wall47 at one end, and a flat toe plate 42 at the other end. A V-shaped internal wall 37, which mirrors the upper wall 47 extends from one side wall to the other side wall. The shaft 32 passes through a diamond shaped hollow tubular portion 39 acting as a tunnel 39 (concealed in the drawings) formed by the upper wall 47 and the internal wall 37 in conjunction. The shaft 32 can also be seen to pass along that valley within the V-shape of the internal wall 37. The internal wall 37 provides strengthening to the main body portion 36 when it is compressed as the nuts 34 are tightened.

A short front wall 48 extends part way down that face of the main body portion which is adjacent the wall face 40. The front wall 48 is not visible in the drawings except for its retaining tab 48 which protrudes into a corresponding hole through the side walls 44 and 45.

Serrated portions 38 are located on the edges of the side walls 44 and 45 where those to walls protrude beyond the front wall 48. The serrated portions 38 engage with the face 40.of the retaining wall 12 to assist grip. The toe plate 42 carries coarser teeth 50, which protrude to provide a non-slip characteristic to the lower end of the jaw portion 28.

A little below the level of the central edge of the internal wall 37 a shoulder 52 in the body 36 accommodates a horizontal plate 54 which protrudes well beyond the front wall 48 and also protrudes beyond each side 44, 45 of the main body 36. The sideways extensions of the plate 54 provides a platform on each side of the shaft 32 from which a. pair of sockets 55 and 56 arise. Each socket 55 and 56 is a length of rectangular hollow tube welded to the plate 54 and to the respective side wall 44, 45. Each socket in use becomes the means by which a foot 31 of a fence panel engages with the clamp assembly 18. The socket is thus an engagement means.

The fence post foot 31 is a loose sliding fit within the rectangular socket laterally of the wall 12 but with significant clearance longitudinally to the wall. This means the fence panels will not unduly wobble laterally to the wall but there is significant tolerance in positioning of the panel posts 23 and 24 longitudinally of the wall.

In use the frontwards protrusion of the plate 54 serves three purposes. The first purpose is to transfer downwards load from the fence posts in the sockets 55 and 56 to the top face 13 of the wall so that the entire weight of the fence panels is not taken by the serrated edges 38 and teeth 50. The second purpose is to assist correct alignment of the jaw portions 28 and 30. The third purpose is to keep the thread 33 clear of the top of the wall.

Due to the positioning of the sockets 55 and 56 on the clamp assembly 18, the fence 5 panels 14 are positioned not directly above the top face 13 of the wall but are instead horizontally offset from the top of the wall. This is best seen in Figure 4. A temporary fence may accordingly be erected on a wall even though a structure of some type, such as a timber wall frame or a series of verandah posts, may already be attached to the top face of the wall. Such a structure already on the wall would not 10 interfere with the erection of the security fence 10 providing sufficient spaces could be found to lay the clamp assemblies 18 across the top of the wall.

The second jaw portion 30 has a main body portion 66 fabricated from sheet steel as a thin-walled structure which is hollow except for a V-shaped internal wall 67. The thin-walled box-like structure provides substantial strength at minimum weight.

The main body portion 66 has two flat side walls 74 and 75, a rear wall 76, a dual pitched upper wall 77 at one end, and a flat toe plate 72 at the other end. A V-shaped internal wall 67, which mirrors the upper wall 77 extends from one side wall to the other side wall. The shaft 32 passes through a diamond shaped hollow tubular portion 69 acting as a tunnel (concealed in the drawings) formed by the upper wall 77 and the internal wall 67 in conjunction. The shaft 62 passes along the valley within the V shape of the internal wall 67. The internal wall 67 provides strengthening to the main body portion 66 when it is compressed as the nuts 34 are tightened.

A short front wall 78 extends part way down that face of the main body portion which is adjacent the wall face 41. The front wall 78 is not visible in the drawings except for its locating tab 78 which protrudes into a corresponding hole through the side walls 74 and 75.

Serrated portions 68 are located on the edges of the side walls 74 and 75 where those walls protrude beyond the front wall 78. The serrated portions 68 engage with the face 41 of the retaining wall 12 to assist grip. The toe plate 72 carries coarser teeth 80, which protrude to provide a non-slip characteristic to the lower end of the jaw portion 30.

5 Mounted on the pitched up walls 77 is a circular socket of smaller diameter than the sockets 55 and 56. Socket 82 is intended to accept a square section tube being the support post for a fallguard safety rail. In this way the clamp assembly 18 may be used for supporting a fallguard on a wall in addition to is primary function of supporting a temporary security fence. There may be situations where the portions of the temporary security fence may be need to be removed to allow appropriate access but there still needs to be a safety rail in position to prevent the possibility of workers falling over the retaining wall 12.

The main body 66 of the second jaw portion 30 has a somewhat narrower body transverse to the wall face than the corresponding main body 36 of the first jaw portion 28. This is due to the lower loads on the jaw portion 30 because the fence panels are not bearing down upon it.

The upper portion of the main body 66, which houses the internal wall 67 and the tunnel portion 69, extends beyond the front wall 78 to overlap the top face 13 of the wall. This serves to properly locate the tunnel 69 relative to the top face of the wall and to distribute any downward load onto the wall rather than it being taken by the teeth 80 and serrated portions 68.

The fence assembly 110 and its components shown in Figures 5 to 8 share most of the characteristics of the fence assembly 10 shown in Figures 1 to 4. The jaw portion 130, threaded shaft 132, winged nuts 134 and fence panels 114 are all identical to the corresponding components described with reference to Figures 1 to 4.

The most significant difference is that whereas the sockets 55 and 56 in Figures 2 to 4 are side by side and oriented in a line at right angles to the shaft 32 which extends between them, the sockets 155 and 156 in Figures 6 to 8 are side by side and oriented in a line parallel to the shaft 132 with both sockets 155 and 156 positioned on the same side of the shaft 132. To facilitate this: - the main body 136 of the jaw portion 128 is longer than the corresponding main body 36 in the direction of the shaft, 5 - a longer plate 154 extends beyond the side wall 145 to provide a support base for both sockets, but does not extend out beyond the other side wall 144, and - the plate 154 also extends out over part of the top face 113 of the wall.

The fence assembly 10 in Figure I has all of the fence panels 14 aligned end to end in 10 a row because the sockets 55 and 56 are all the same distance from the face 40 of the wall and are aligned at right angles to the shaft 32. In contrast, the sockets 155 and 156 on the clamp assemblies in the fence assembly 110 shown in Figure 5 are side by side and aligned parallel to the longitudinal axis of the shaft so that the respective planes of adjacent fence panels are offset relative to each other.

The components of the fence assembly 210 shown in Figures 9 and 10 share many of the characteristics of the components of the fence assembly 10 shown in Figure 3. The jaw portion 230, threaded shaft 232, winged nuts 234 and fence panels 215 and 216 are all identical to the corresponding components described with reference to Figure 3. However the jaw portion 228 has only a single socket 256 and into this is inserted the post 224 of fence panel 215. The adjacent post 223 of panel 216 does not engage an upright engagement means such as a socket or stud on the clamp assembly 218 but instead simply rests upon (and is therefore partially supported by) the horizontal plate 254 while the lower portion of the post is restrained by a joiner 259 which clamps onto the posts 223 and 224 to hold the post 223 at a fixed distance from the post 224.

The fence assembly 210 has joiners (not shown in Figures 9 or 10) at the top of the panels like the joiners 29 described with reference to Figure 1. The joiners 259 are the same in structure and function to the joiners 29. Although the foot 231 of the post 223 is not directly supported by the socket 256, it is indirectly supported by that socket by way of connection with the post 224 which is in turn engaged with the socket,

Whilst the above description includes the preferred embodiments of the invention, it 5 is to 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.

1o For example, for additional security the threaded shaft may alternatively be provided with an enlarged head, preferably a rounded domed head, so there is a nut located on only one end, namely the end positioned within the building site.

Also the embodiments shown in Figures 1 to 4 may be varied by replacing the jaw 30 with ajaw the same as jaw 28. Similarly the embodiments shown in Figures 5 to 8 may be varied by replacing the jaw 130 with a jaw the same as jaw 128. These alternatives have the advantage of reducing the variety of components that need to be provided at the fence erection site.

Also, the posts on the fence panels need not engage with the engagement means in a sliding manner. The engagement could alternatively be by way of a clamp or pinning or bolting.

Also, instead of there being two engagement means (studs or sockets) on the clamp assembly, there may be only a single engagement means into which both fence panel posts engage or alternatively, which only a first post engages while the second post is fastened to the first post, perhaps by a connector like the joiners 29 shown in Figure 1.

Also, alternative embodiments of the clamp assembly do not necessarily use a threaded shaft in order to tighten the clamp assembly onto the wall. Such alternatives could use known systems such as ratchets or cam tightening systems for example.

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 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.

Claims (47)

Claims

1. A clamp assembly adapted to clamp across the top of a wall in order to provide a support for two panels of a temporary fence, said clamp assembly comprising a pair of jaw portions adapted to move towards and away from each other in a first direction, said jaw portions including an engagement means adapted to engage with a post on said panels to thereby retain said post in an upright position.

2. A clamp assembly according to claim 1 wherein said engagement means is adapted to engage said post in a sliding fit.

3. A clamp according to claim I or 2 wherein said jaw portions include a pair of said engagement means aligned with their longitudinal axes at right angles to said first direction, each said engagement means being adapted to engage in a sliding fit with respective post on said panels to thereby retain said respective post in an upright position.

4. A clamp according to any one of claims 1 to 3 wherein: - said pair ofjaw portions are slidably engaged with a threaded shaft, and - a nut is threadedly engaged with said shaft whereby tightening said nut causes said jaw portions to be urged towards each other in said first direction.

5. A clamp assembly according to claims 3 or 4 wherein one of said jaw portions includes both of said engagement means.

6. A clamp assembly according to claim 5 wherein said engagement means are oriented in a line at right angles to the longitudinal axis of said shaft.

7. A clamp assembly according to claim 5 wherein said engagement means are oriented in a line parallel to the longitudinal axis of said shaft.

8. A clamp assembly according to any one of claims 3 to 7 wherein each said engagement means is a tubular socket adapted to in use receive therein its said respective post.

5 9. A clamp assembly according to claim 8 wherein said socket has a rectangular hollow cross section transverse to the socket's longitudinal axis.

10. A clamp assembly according to any one of claims 3 to 7 wherein each said engagement means is an elongate stud adapted to slide in use into the lower end of its said respective post.

11. A clamp assembly according to any one of claims 3 to 10 wherein a said jaw portion includes a further and smaller engagement means extending parallel to said pair of engagement means and adapted to engage in a sliding fit with an end of a post is of a falguard handrail assembly.

12. A clamp assembly adapted to clamp across the top of a wall in order to provide a support for two panels of a temporary fence, said clamp assembly comprising: - a pair ofjaw portions slidably engaged with a threaded shaft, - a nut threadedly engaged with said shaft whereby tightening said nut causes said jaw portions to be urged towards each other, and - said jaw portions including a pair of engagement means aligned with their longitudinal axes at right angles to said shaft, each said engagement means being adapted to engage with a respective post on said panels to thereby retain said respective post in an upright position.

13. A clamp assembly according to claim 12 wherein each said engagement means is adapted to engage said respective post in a sliding fit.

14. A clamp assembly according to claim 12 or 13 wherein one of said jaw portions includes both of said engagement means.

15. A clamp assembly according to claim 14 wherein said engagement means are oriented in a line at right angles to the longitudinal axis of said shaft.

16. A clamp assembly according to claim 14 wherein said engagement means are 5 oriented in a line parallel to the longitudinal axis of said shaft.

17. A clamp assembly according to any one of claims 12 to 16 wherein each said engagement means is a tubular socket adapted to in use receive therein its said respective post.

18. A clamp assembly according to claim 17 wherein said socket has a rectangular hollow cross section transverse to the socket's longitudinal axis.

19. A clamp assembly according to any one of claims 12 to 16 wherein each said engagement means is an elongate stud adapted to slide in use into the lower end of its said respective post.

20. A clamp assembly according to any one of claims 12 to 19 wherein a said jaw portion includes a further and smaller engagement means extending parallel to said pair of engagement means and adapted to engage in a sliding fit with an end of a post of a fallguard handrail assembly.

21. A clamp assembly according to any one of claims 12 to 20 wherein said shaft is threaded along its entire length, two nuts are threadedly engaged with said shaft and said jaw portions are captive on the shaft between said nuts.

22. A clamp assembly according to any one of claims 12 to 20 wherein said shaft has an enlarged head on one end and said jaw portions are captive on the shaft between said head and said nut.

23. A clamp assembly according to any one of claims 12 to 22 wherein said nut or nuts have wings whereby said nut or nuts may be tightened without tools by using two hands.

24. A clamp assembly according to any one of claims 12 to 23 wherein each of said jaw portions comprises a main body portion having a hollow tubular portion through which said shaft passes and a hollow clamping portion which bears onto a respective side of the wall.

25. A clamp assembly according to claim 24 wherein said main body portion is thin-walled,

26. A clamp assembly according to claim 25 wherein said hollow clamping portion has flat walls the edges of which protrude as teeth for engagement with a surface to which said clamp assembly is being clamped.

27. A clamp assembly according to any one of claims 24 to 26 wherein each said main body portion has a V-shaped internal wall extending from one side of said main body portion to the other side of said main body portion and said shaft passes along the valley formed by the V-shape.

28. A clamp assembly according to any one of claims 12 to 27 wherein a first of said jaw portions has a said engagement means upstanding from a plate positioned alongside said shaft and said plate protrudes out towards the second said jaw portion.

29. A clamp assembly according to claim 28 wherein both of said engagement means are upstanding from said plate alongside said shaft.

30. A clamp assembly according to claim 29 wherein both of said engagement means are upstanding on the same side of said shaft.

31. A clamp assembly according to claim 29 wherein said shaft extends between said engagement means.

32. A security fence assembly for a building site, said fence assembly extending upwards from a wall and comprising an array of upstanding fence panels supported by a plurality of clamp assemblies, wherein: - each said fence panel comprises two vertical posts, - each said clamp assembly is clamped across the top of said wall, - each said clamp assembly comprises a pair of jaw portions moveable towards and away from each other in a first direction transverse to the wall, - said jaw portions of each clamp include an upstanding engagement means engaged with a respective said post to thereby retain and support said respective post in an upright position.

33. A security fence assembly according to claim 30 wherein said upstanding engagement means is engaged in a sliding fit with said respective said post to thereby retain and support said respective post in an upright position.

34. A security fence assembly according to claim 32 or 33 wherein each said post is retained and supported in a vertical position by a separate said clamp assembly.

35. A security fence assembly according to any one of claims 32 to 34 wherein a said engagement means engages with a first said post of a first said fence panel while a second said post of an adjacent panel is fastened directly to said first post and not engaged with any said upstanding engagement means.

36. A security fence assembly for a building site, said fence assembly extending upwards from a wall and comprising an array of upstanding fence panels supported by a plurality of clamp assemblies, wherein: - each said clamp assembly is according to any one of claims 1 to 31, - each said fence panel comprises two vertical posts the bottoms of which engage with upstanding said engagement means, and

- each said clamp assembly engages with posts of two of said fencepanels.

37. A security fence assembly according to claim 36 wherein said engagement means and said vertical posts are horizontally offset from the top of the wall. 5

38. A security fence assembly according to claim 36 or 37 wherein a first of said jaw portions includes both of said engagement means.

39. A security fence assembly according to claim 38 wherein the engagement means on each said clamp assembly are different distances from the wall.

40. A security fence assembly according to any one of claims 36 to 39 wherein each said clamp assembly is clamped with a threaded shaft extending across the top of said wall and, at each clamp assembly, said engagement means are side by side in a line parallel to the longitudinal axis of said shaft.

41. A security fence assembly according to any one of claims 36 to 40 wherein the respective planes of adjacent said fence panels are offset relative to each other.

42. A security fence assembly according to claim 38 wherein the engagement means on each said clamp assembly are the same distance from the wall.

43. A security fence assembly according to any one of claims 36 to 38 wherein each said clamp assembly is clamped with a threaded shaft extending across the top of said wall and, at each clamp assembly, said engagement means are oriented in a line at right angles to the longitudinal axis of said shaft.

44. A security fence assembly according to any one of claims 36, 37, 38 or 43 wherein the respective planes of adjacent said fence panels are in line with each other.

45. A security fence assembly according to claim 40 or 43 wherein at least one of said jaw portions incudes a plate member which extends to lay on the top of said wall underneath the threaded shaft to prevent the shaft from contacting the top of the wall.

46. A security fence assembly according to any one of claims 36 to 45 wherein each said post bears onto a plate which lies beneath said engagement means and said plate bears upon the top face of said wall.

47. A security fence assembly according to any one of claims 36 to 46 wherein said wall is a masonry retaining wall.