WO2006043039A1

WO2006043039A1 - Scaffolding locking device

Info

Publication number: WO2006043039A1
Application number: PCT/GB2005/003992
Authority: WO
Inventors: Martin John Caudell; Barry Edmund Snell
Original assignee: Martin John Caudell; Barry Edmund Snell
Priority date: 2004-10-18
Filing date: 2005-10-18
Publication date: 2006-04-27
Also published as: GB0423145D0; EP1802829A1

Abstract

A locking device for use with scaffolding apparatus is provided the scaffolding apparatus comprising a first pole having a projection, one or more further poles for coupling to the first pole and a collar having an aperture through which the first pole may pass. The collar further comprises a channel through which the projection may pass. The channel forms part of the aperture, wherein the collar is adapted to be slidably mounted to the first pole such that it may only pass the projection when the projection is aligned with the channel. The apparatus is adapted such that, in use, the collar is slid past the projection of the first pole and further moved to an engagement position in which the first and further poles are fixed in relative orientation by engagement with the collar. The locking device is adapted in use to be coupled to the apparatus such that the collar is prevented from sliding past the projection.

Description

SCAFFOLDING LOCKING DEVICE

Field of the Invention

The present invention relates to a locking device for scaffolding apparatus, in particular to a scaffolding apparatus thereby provided with improved joint integrity, together with a scaffolding system comprising such apparatus.

Background to the Invention

Common scaffolding systems employ networks of horizontal and vertical poles connected together to form a three-dimensional lattice, known as an erection. These scaffolding systems include those known by trade names such as Cuplock, Kwikstage and Modex.

Taking the Cuplock system as an example, this uses a rotatable collar (also known as a "cup") to secure each joint between the horizontal and vertical poles, such that rotation of the collar fixes the poles in place. Rotation of the collar is executed by hitting lugs on the collar surface with a hammer. Similar compatible systems are called Duralok, K-Lock and Toploc.

This system relies on friction to prevent the collars from loosening and thus potentially releasing the horizontal and vertical poles from the joints. However, vibrations may work the collars loose, and anyone can release a collar simply by hitting it with a hammer or other heavy item (eg. a brick). Therefore, unless rigorous and time-consuming checks are carried out regularly, the collars can become released and this may go unnoticed. If, when the collars are released, a horizontal pole were to be removed, typically the scaffolding system may move slightly, thus preventing the replacement of the horizontal pole. As a result, the scaffolding erection may become unsafe.

Consequently, it is desirable to produce a novel scaffolding apparatus wherein the integrity of the joint cannot be compromised, and hence the safety of the erected scaffolding is improved.

Summary of the Invention

According to the present invention, there is provided a locking device for use with scaffolding apparatus, the scaffolding apparatus comprising:- a first pole having a projection; one or more further poles, for coupling to the first pole; and, a collar having an aperture through which the first pole may pass, the collar further comprising a channel through which the projection may pass, the channel forming part of the aperture, wherein the collar is adapted to be slidably mounted to the first pole such that it may only pass the projection when the projection is aligned with the channel; the apparatus being adapted such that, in use, the collar is slid past the projection of the first pole and further moved to an engagement position in which the first and further poles are fixed in relative orientation by engagement with the collar; and wherein the locking device is adapted in use to be coupled to the apparatus such that the collar is prevented from sliding past the projection.

The present invention therefore conveniently addresses the problems discussed above. We have realised that by using a locking device that couples to the apparatus (preferably the collar), the collar can be prevented from sliding past the projection. This ensures that the collar cannot release either the first or the further poles from the joint, and therefore the integrity of the joint is maintained. Further, preferably the locking device is adapted to be irreversibly coupled to the apparatus. This ensures that it cannot easily be removed by vibration or an unauthorised person. Consequently, the safety of the scaffolding is improved. Preferably the locking device is also non-reuseable. In this case the locking device is destroyed on removal, and therefore it cannot be removed or replaced by the public. As a result, the locking device is less likely to be tampered with and the integrity of the erected scaffolding is more likely to be maintained. This improves the safety of the scaffolding erection. The locking device is typically attached to the collar by virtue of a first part of the locking device fitting within the channel of the collar. This first part therefore has suitable dimensions so as to prevent this part and the projection from co-existing within the channel. However, the locking device may alternatively not be fitted within the channel, and may operate by preventing the projection from accessing the channel. This may occur by preventing the collar from aligning with the channel or by covering the entrance to the channel. Any combination of the above mechanisms is also envisaged. For example, the locking device may comprise a second part which is too large to fit within the channel, such that the first and second parts are connected. One or each of such parts may be tapered or stepped. One or each of the first and second parts may be solid, hollow or solid in part (such as containing voids or bores). If relative alignment between the projection and channel is to be- prevented, then the locking device may comprise a part which contacts with the projection so as to prevent the relative alignment. The collar may also have a surface adjacent the channel. A suitably formed locking device can prevent the relative alignment because the locking device becomes trapped between this surface and the projection. The locking device may be formed from a resilient material such as rubber or another elastomer. In this case part of the device may effectively act as a bung. In examples where part of the device is positioned within the channel, the bung may be forced into the channel, either partially or completely, making its removal difficult. Since typically the collar has to slide a small distance past the projection before the further poles can be removed from the joint, even if someone tampers with a bung, leaving only part of it in the channel, the joint still retains its integrity, particularly if the projection is prevented from entering the channel at all.

In other examples, the part of the locking device that prevents the projection from entering or passing through the channel when the locking device is present, is a pin of prismatic shape and typically of constant cross-section such as a cylinder. This pin may be hollow (tubular), solid in part or fully solid. The pin is preferably about 50 mm long and typically has a diameter of about 10 mm. The pin therefore occupies most or substantially all of the free volume within the channel. Various cross-sections of the pin are envisaged, including circular and polygonal sections. Metal, elastomeric or plastics materials can be used to form such a pin.

Referring now by way of further explanation, to the interlocking network of first and further poles, it is typical that each first scaffolding pole is positioned substantially vertically when erected. This first pole may therefore be a "standard". Different lengths of standard are known, such as 1 , 2 or 3 metre lengths. Each further scaffolding pole is typically positioned substantially horizontally when in use, and connected to the first at a joint. These may be "ledgers", or handrails. Lengths of these can vary from 0.6 to 3.0 metres, typical lengths are between 1.3 and 2.5 metres. Each of the first and further scaffolding poles are typically composed of metal (such as steel), and preferably they are hollow with a circular cross section. Although the collar is typically fitted upon a vertical pole it will be appreciated that, it could also be fitted to a pole in any other orientation.

In most cases the collar is adapted to engage tightly with the first and/or further poles by friction when in the engagement position. Preferably this occurs by contact between the collar and the projection, this projection typically being formed on a cylindrical surface of the first pole. The projection is typically elongate and aligned to have the long dimension parallel with the longitudinal axis of the first pole.

The first and further scaffolding poles are held in position by at least the collar. Generally, the collar is moved to the engagement position by rotation of the collar about the longitudinal axis of the first scaffolding pole. This rotation typically wedges the collar between the projection and the further poles, because the top and bottom surfaces of the collar (ie. the opposed top and bottom surfaces which are substantially normal to the longitudinal direction of the collar) are not parallel. In detail, the separation between these surfaces increases towards the engagement position, such that upon rotation, the top and bottom surfaces become wedged between the projection and the further poles.

Preferably, the scaffolding apparatus used in accordance with the present invention additionally comprises a fixed cup which acts as a cradle to support the further pole(s). This fixed cup is located on the first scaffolding pole such that the corresponding further scaffolding poles engage with the fixed cup and are gripped between the collar and the fixed cup when the collar is in the engagement position. To facilitate this, the further scaffolding pole(s) each preferably comprise tongues that engage with the collar and/or the fixed cup.

Turning now to the locking devices in more detail, it is preferred that each locking device is tamper-evident. This may mean that it is highly visible by having for example a brightly coloured label, the presence or absence of which can be clearly seen.

Alternatively or in addition, the locking device may comprise a part which changes colour upon being exposed to a stress, strain or heat, above a certain predetermined magnitude. The locking device can also be rendered tamper-evident by making different parts of the device different colours, such that movement of the device exposes certain colours. Furthermore, a marker may be provided where attempted tampering with the device may cause removal of the marker, which cannot then be reinstalled properly. It will therefore be evident if the position of the locking device has been altered, or if someone has attempted to remove it by weakening parts of the device. The person inspecting the scaffolding will then easily identify the missing or damaged locking device and be able to replace it. Again this improves the safety of the erected scaffolding apparatus by increasing the likelihood that the integrity of the joints-will be maintained.

In order to prevent the removal of the locking device, typically the locking device further comprises a first and a second fastening member, these members being adapted to be coupled together so as to lock the locking device to the remainder of the apparatus, such as the collar. In one example the first fastening member is a circumferential groove formed within an external surface of a locking device pin, and the second fastening member is a clip for attachment to the collar. The clip has an aperture through which part of the pin may pass such that the groove may be aligned with the aperture. To effect the locking, the part of the pin which passes through the aperture is formed from a resilient material such that the said part of the pin may be passed through the aperture in the clip by deformation. The part of the pin forming the groove thereafter engages with the aperture edge to lock the pin within the channel.

In other examples, the first fastening member is a tail of a ratchet fastener and the second fastening member is a locking head of a ratchet fastener. In another example, the first fastening member may take the form of a tail which is provided with one or more pairs of barbs, the barbs of each pair being located upon opposed sides of the tail. The second fastening member may then comprise a part having a slot through which the tail of the first fastening member may only pass in one direction by the resilient deformation of the sides of the slot and/or the barbs. The second part of the device may have a tabular section within which is located the slot of the second fastening member.

Alternatively the first fastening member may be a wire of variable diameter and the second fastening member may be a corresponding crimp. In other cases the first and second fastening members are adapted to be glued or fused/sealed together. The roles of the first and second fastening members may be interchanged in each case.

The first fastening member may be integral with the locking device. Alternatively or in addition, the second fastening member may be integral with the locking device. As a further alternative, the first and second fastening devices may be integral, albeit not with the locking device. This latter case might be where the pin is in the form of a tube and the first or second fastening devices are threaded through the tube. The first and second fastening members may be coupled upon one side of the locking device. This might be the case where one of the first and second fastening members is of sufficient size to prevent it passing through the channel. Otherwise, the first and second members may be coupled so as to form a closed loop.

As in the case of the remainder of the locking device, either or each of the first and second fastening members may be tamper evident. Typically they are formed from suitable materials such as metals or plastics. If a fastening member is a wire, this wire may comprise a single wire, several twisted wires or a variable diameter wire.

Suitable plastics include nylon and PTFE.

The first aspect of the invention therefore provides a locking device for scaffolding apparatus, particularly in terms of joints between first and further poles, and for which the integrity and safety can be improved by the use of a locking device. In accordance with a second aspect of the present invention, we provide a scaffolding system comprising:- a plurality of locking devices according to the first aspect of the invention; a plurality of scaffolding apparatus, each apparatus comprising:- a) a first pole having a projection; b) one or more further poles, for coupling to the first pole; and, c) a collar having an aperture through which the first pole may pass, the collar further comprising a channel through which the projection may pass, the channel forming part of the aperture, wherein the collar is adapted to be slidably mounted to the first pole such that it may only pass the projection when the projection is aligned with the channel; each apparatus being adapted such that, in use, the collar is slid past the projection of the first pole and further moved to an engagement position in which the first and further poles are fixed in relative orientation by engagement with the collar; wherein each locking device is adapted in use to be coupled to the respective apparatus such that the collar is prevented from sliding past the projection.

A third aspect of the present invention includes the system of the second aspect, in an erected state. Brief Description of the Drawings

Some examples of the present invention will now be illustrated with reference to the accompanying drawings in which:-

Figure 1 shows a general view of a prior art scaffolding apparatus joint; = ■ - Figure 2 shows a first example of a scaffolding apparatus according to the present invention;

Figure 3 shows a collar according to the first example;

Figure 4 shows a locking device according to the first example;

Figure 5 shows the fitting of the locking device according to a first example; Figure 6 shows a locking device according to a second example;

Figure 7 shows a third example of a locking device;

Figure 8 shows a modification to the third example;

Figure 9 shows a fourth example of a locking device;

Figure 10 shows a fifth example of a locking device; and Figure 11 shows a sixth example of a locking device.

Description of Examples

Figure 1 is a general view in perspective of a joint between poles in a prior art "Cuplock" scaffolding apparatus. In Figure 1 , a vertically oriented first scaffolding pole 10 and three horizontally oriented further scaffolding poles 14 form a joint in a scaffolding apparatus. It will be appreciated that, whilst one such joint is described herein and with reference below to the invention, a scaffolding system in each case generally comprises a number of such vertical and horizontal poles connected together by corresponding apparatus. The poles each are generally circular in cross-section and formed from steel.

The first pole 10 comprises a projection 12 on its curved (cylindrical) surface, wherein the projection 12 is elongate, having the direction of elongation parallel to the longitudinal axis of the first pole 10. This projection 12 is situated at a position just above a location where the further scaffolding poles 14 are located when secured within the joint.

The joint is held together in use by a collar 16. The collar 16 is adapted to be slidably mounted upon the first pole 10. As is best seen in Figure 3, the collar 16 has a central cylindrical aperture 18. This has a diameter just larger than that of the first scaffolding pole, the aperture passing fully through the thickness of the collar. On an inner wall of the cylindrical aperture 18 a channel 20 is provided which also passes through the thickness of the collar 16. The channel has a "U" shaped cross-section, the arms of the "U" opening into the cylindrical aperture 18 such that the channel 20 forms a sub-aperture through the thickness of the collar 16. The dimensions of the channel are arranged to be just larger than those of the projection on the first pole so that the collar 16 cannot pass along the first pole beyond the position of the projection 12 unless the channel 20 is aligned with the projection 12. Only with suitable alignment of the projection 12 and channel 20, may the collar 16 be slid past the projection 12 with the projection 12 itself passing through the channel 20. The collar 16 also comprises a number of lugs 32 (only one of which is shown in Figure 3) which, when hit with a hammer or other suitable tool, facilitates rotation of the collar about the longitudinal axis of the first pole.

With further reference to Figure 3, the collar 16 also comprises a top surface 17, that is, an uppermost surface which is substantially normal to the longitudinal direction of the collar 16. The majority of the top surface 17 is inclined as a function of rotational angle about the general cylindrical axis of the collar. It therefore effectively defines a helical path. The respective ends of the top surface 17 are joined by a part 19 which surrounds the end of the channel 20. With the first pole 10 oriented vertically and the collar 16 fitted, this part 19 lies at the bottom of the spiral slope of the surface 17. The height of the top surface 17 increases as one traverses around the top surface 17 until a maximum height is reached just before returning to the part 19. This maximum height is connected to the minimum height of part 19 by a vertical section 21.

The lower part of the collar defines a flange part 6, having a significantly larger diameter than that of the first pole. The purpose of the flange 6 is to define an annular space between the first pole 10 and the flange 6 which, in use, accommodates tongues which project from the further pole ends (described below). This allows the further poles to be held firmly by friction with the collar 12 via the tongues. The flange 6 also comprises a bottom surface 23, which is a lowermost surface of the collar 16, all parts of which are substantially normal to the longitudinal direction of the collar 16. As can be seen in both Figures 1 and 3, the bottom surface 23 is substantially horizontal when in use. The combined effect of the top 17 and bottom 23 surfaces is that the top-to-bottom thickness of the collar is a function of the position about the collar central (cylindrical) axis. The first pole 10 additionally comprises a fixed cup 28. As is best shown in

Figure 1 , this fixed cup 28 is mounted on the first pole 10, below the level of the further scaffolding poles 14. The upper part of the cup 28 has a larger diameter than that of the first pole 10. This defines an annular opening, analogous to that defined by the flange 6.

The ends of the further scaffolding poles 14 are each fitted with tongues 5 which project in two (opposed) directions substantially normal to the cylindrical axis of the further poles. The tongues 5 have a shape which is conformal with the surface of the first pole to which they are adapted to abut, so as to form the joint. The tongues 5 are sufficiently narrow in thickness to fit snugly into the annular spaces defined by the flange 6 and first pole 10, and the cup 28 and first pole 10.

To assemble the joint, the first pole is positioned vertically and the further poles are arrange so that their tongues 5 (downwardly oriented) fit into the annular space provided in the fixed cup 28. The collar 16 is then slid down the pole and rotated to the correct orientation such that the projection 12 passes through the channel 20. This allows the top surface 17 of the collar to just pass the position of the projection 12. In this position the upwardly oriented tongues 5 now locate into the annular space provided by the flange 6 and the bottom surface 23 contacts with the cylindrical surfaces of the further poles. Referring to Figure 1 , the collar 16 is then rotated (clockwise when looking down the first pole from above) about the first pole using a hammer by impacting the hammer against one or more of the lugs 32. Due to the rising nature of the surface 17, the collar eventually becomes wedged by friction between the projection (engaging with the top surface 17) and the further poles 14 (engaging with the bottom surface 23). The collar is then in an engaged position in which the first and further poles are held firmly in fixed relative orientation. To dismantle the joint, the reverse procedure is adopted, using a hammer to loosen the collar by hitting the lugs 32 in a counter¬ clockwise direction.

Looking now at Figure 2, this shows a first example of a scaffolding system according to the present invention. This scaffolding system comprises a prior art scaffolding joint as shown in Figure 1. In addition, a locking device 40 is provided.

The locking device 40 comprises a solid cylindrical pin 24, which in use, is positioned such that it passes through at least part of the channel 20 (as shown in

Figure 2). In this case the pin has a diameter just less than the channel 20 and a length in excess of that of the channel. Integral with the pin 24, a fastener 26 is provided in two parts (first and second fastening members) which project respectively from either end of the pin 24. The two parts of the fastener 26 are adapted to be coupled together to form a closed loop. The locking device 40 may be formed from a. number of different materials including metals, although a hard plastic provides advantages in terms of low cost and formability. In this example, the locking device 40 also comprises a label 30 (as an additional component although this could be integral also), coated with or containing a fluorescent dye, such that the device is highly visible. This could be coated or printed with a paint/dye and may include warning symbols or text.

There are various ways in which the respective ends of the fastener could be coupled together. However, it is important that this locking is irreversible such that the device can only practically be removed by destroying it. This ensures the integrity of the joint is maintained and has therefore corresponding safety benefits. In this particular embodiment, the fastener 26 comprises a "ratchet fastener" having a similar action to ratchet ties used for gardening or domestic applications, these having a "tighten only" action.

The locking device 40 improves the integrity and safety of the scaffolding since, if the collar 16 becomes loose, the collar is unable to move past the projection 12 on the first pole 10. This is because in the present example the pin is positioned within the channel and there is insufficient volume within the channel to accommodate both the pin 24 and the projection 12. If the pin is arranged to be longer than the channel 20 as in Figure 2, the upper part of the pin 24 engages with the projection 12 and prevents the projection 12 and channel 20 even from coming into relative alignment. This may occur by the projecting part of the pin being squeezed between the projection and the surface of the section 21.

Figure 4 shows the locking device 40 of Figure 2 in more detail. A first part of the fastener 26 comprises a tail 36 having a ratchet surface (formed from asymmetrical saw-tooth relief in a known manner). A second part has a locking head 34, the tail being adapted to pass through an aperture 35 in the head 34. A deflectable resilient part within the head contacts the ratchet surface to provide the one-way tightening action required. Together the ratchet tail 36 and the ratchet head 34 form the fastener 26. The fastener can therefore be tightened but not loosened. As explained above, the pin 24 shown in Figure 4 is a solid cylinder and adapted to fit into the aperture 20 of the collar 16. The pin 24 in this example is about 50 mm in length and 10 mm in diameter.

Figure 5 shows the attachment of the locking device to a joint when in the locked position. The part 36 of the fastener is passed through the channel 20 until the pin 24 is located within the channel 20. The part 36 can optionally then pass through a loop in a label 30 (not shown) and then through the aperture 35 in the head 34 (as in Figure 2). This is then tightened. The pin 24 is therefore retained effectively irremovably within the channel as is shown in Figure 2. The only way in which the joint can now be released is to cut the fastener thereby destroying it, for example using wire cutters. Removal of the fastener causes the label to be removed also, resulting in the missing tie being conspicuously absent.

A second example of a locking device 40' is shown in Figure 6. This device 40' comprises a metallic pin 24'. This has external dimensions similar to that shown in Figure 4, although in this case the pin is a hollow tube. A fastener 26' in this case is no longer integral with the pin 24'. The tie 26' is formed from a length of metal wire having a periodically variable diameter. Close to one end of the wire a crimp seal 36 is provided, formed from lead for example. The crimp seal 36 has a narrow bore passing through it, this being of sufficient size to allow passage of the other end of the wire. In use, the pin 24' is placed in the channel 20. The end of the wire distal to the crimp seal 36 is passed through the hollow bore of the cylinder and then through the bore of the seal 36 to form a closed loop. This is then tightened and secured by the seal being crimped with a suitable crimping tool. As in the example above, a label may be used to provide a visible indication of integrity. The irreversible fitting of the locking device 40" is thereby effected. To remove the device 40' and undo the joint, the wire must be cut.

Figure 7 shows a further example of a locking device. This is a simpler form of such a device which generally takes the form of a rubber or plastic "cork" or bung. This is adapted to be fitted within the channel 20 and is hammered home into the channel in the collar after the collar has been tightened so as to assemble the joint. As before, the typical length of the bung is about 50millimetres, with a diameter designed to produce an interference fit in the channel 20. The bung is generally shown at 50 in Figure 7. A series of ridges or non-symmetrical protrusions 51 are placed on the outer surface of the bung 50 in a lower part 53 thereof to assist in the interference fit and to increase the force needed for extraction. A top part 52 of the bung 50 is exposed (above the channel) in use and may be provided with a brightly coloured material or surface so as to increase its visibility. It may also have a different diameter or profile in comparison with the lower part 53 of the bung 50. Since the Cuplock system has only limited access to the channel from underneath the collar, there is reduced opportunity to drive the bung out of the channel from underneath.

As before, it is desirable for the locking device to be destroyed when it is removed. To achieve this, the top part 52 of the bung 50 is weakly coupled to the lower part 53 so that it will prevent extraction of the bung, the join between these parts being illustrated at 54. This is positioned adjacent to the upper opening of the channel 20 or within the channel 20 when in use. The weakened part is achieved by manufacturing the bung 50 from two separate parts 52,53 and using a weak glue to hold the upper 52 and lower 53 parts together. Alternatively, these parts may be manufactured together although partially separated at manufacture either by cutting or by inserting a disruptive or non-connected layer in the middle.

In order to remove the bung 50 so as to release the collar 16 and dismantle the scaffolding, the top part 52 is broken away and the lower part 53 is then removed from the channel 20 using an extraction tool specifically designed for the purpose. This tool may have an operation which is analogous to that of a corkscrew. Figure 8 shows a modification to the third example, in this case an elongate solid central plunger 55 is provided which is driven into the bung 50 when the bung is fitted within the channel 20 so as to expand the surrounding bung material and to increase the frictional fit with the internal surfaces of the channel. The ability of the relevant parts of the bung 50 to be expanded can be enhanced by the provision of a longitudinal slit 56 rising from the lower surface of the part 53 and dividing the bung 50 into approximately two halves in this lower part 53. Once again, the upper part 52 may be brightly coloured.

In order to remove the bung 50 in Figure 8, the plunger 55 is bent to give it adequate purchase to remove the bung. This provides a tamper-evident feature since it is extremely difficult to straighten the plunger 55 without destroying the bung 50.

A fourth example is shown in Figure 9, this having a bung 100 and a corresponding clip 101 , which act together as the locking device. At least a lower part of the bung 100 is formed from a resilient (compressible) material such as rubber. In the present example, the entire bung is formed from such a material. The clip 101 is formed from a metal/plastic or other suitable material. It may for example be formed from sheet metal and then deformed into the correct configuration. Alternatively, it may be formed from wire. The clip 101 has an upper part 102 and a lower part 103 each projecting in a substantially perpendicular manner from a central connecting part 104. The length of the central connecting part-104 is approximately that of channel and the parts 102, 103 are adapted to fit over the top and bottom ends of the channel 20. When fitted to the collar, the bottom part 103 prevents access to the channel 20 from beneath, whereas the top part 102 contains an aperture 105 having a diameter which is slightly less than that of the channel 20. In order to fit this locking device, the clip 101 is placed on the collar such that the bottom part 103 blocks the lower part of the channel and the top opening of the channel is accessible through the aperture 105. The bung 100 is then inserted into the channel through the aperture 105. Since this bung is made of compressible material, it may be squeezed by force through the aperture 105 which is less than the diameter of the bung 100.

At a position approximately halfway along the bung 100, a circumferential groove or shoulder 106 is provided having a narrower diameter. This means that when the plug is forced into the channel 20, the aperture 105 in the clip 101 becomes aligned with the groove 106. The expansion of the material below the groove 106 prevents the plug from then being pulled out of the channel 20. This can thereafter only be removed by breaking the clip, by cutting the bung 100 or by a combination of both of these actions. By providing the plug and the clip with high visibility colouring a quick identification can be made to ensure that the bung 100 and clip 101 are correctly positioned. It is therefore envisaged within the scope of the invention that non-closed loop devices can be provided.

Figure 10 shows a further example which is a modification of the example of Figure 4. Here a locking device 200 is provided with a tapered pin 201. One end 202 of the tapered pin is therefore of narrower diameter than the other end 203. The narrower diameter end 202 may fit within the channel 20 whereas the other end 203 may not. The pin may be formed from a metal or plastic, although a rubber pin is provided in this case. An integral first fastening member is provided in the form of a tail of a ratchet fastener 204 (analogous to the part 36 in Figure 4). This extends from the narrower end 202. When in use, with the collar 16 positioned so as to hold the poles in their assembled orientation, the tail 204 is threaded through the channel 20 followed by the narrow end 202 of the pin. Since the end 203 is too large to fit within the channel, due to the tapering, the pin lodges in the channel 20. A typical length of the pin is about 50 millimetres. A second fastening member 205 is provided as part of the locking device 200 so as to lock the pin within the channel 20. The second member 205 comprises a locking head for engaging with the tail 204. This is analogous to the head part of the component 34 in Figure 4. The tail 204 is threaded through the head 205 and the head moved up the tail until it attains a tightened position just beneath the narrow end of the pin 202. Note that the head 205 is too large to pass upwards into the channel. Thus the locking device 200 is irreversibly locked to the collar with the tapered pin 201 within the channel 20.

This can be removed by cutting the locking head part 205 or, if the head is not fully tightened, by cutting a small exposed part of the tail 204 between the pin 201 and the head 205. As before, this locking device 200 may be provided with a highly visible indication that it is correctly installed.

As a further example, heat treated metallic pins could be used which are fitted into the channel with the metal in an annealed state. The pins could then be secured into position by bending them using a hammer. The work-hardening within the metal would then provide an irreversible action since later straightening the pins would be impractical. Such pins could be cut through in order to facilitate removal.

A further example of a locking device according to the invention is shown in Figure 11. This locking device comprises a first part 300 which is generally cylindrical and solid. In use, this first part 300 fits within the channel 20 to prevent entry of the projection 12 into the channel 20. The first part incorporates a cylindrical section 301 and a cut-away section 302 to cater for different amounts of cup rotation.

The cylindrical section 301 of the first part is joined to a second part 303 which is partially hollow (due to the presence of three parallel rectangular voids). The second part has a diameter too large to fit within the channel 20 and prevents the channel 20 being aligned with the projection 12. This provides a highly visible part when fitted such that the use of a number of the devices upon different joints provides a uniform visual impression when correctly fitted and viewed from a distance. The second part also prevents the cylindrical section of the first part from being forced through the channel and provides a large volume for contact with the projection of the respective pole. The second part incorporates a larger tabular section 304 at its distal end. The locking device further comprises first and second fastening members. The first fastening member is an elongate, thin and flexible tail 305 having pairs of barbs which project from opposite sides of the tail at a number of regularly spaced locations along its length. The second fastening member is a slot 306 formed within the tabular section 304. In use, the barbed length 305 is fed through the slot 306 such that the barbs resiliently deform and pass through the slot. The barbs will not, however, allow the barbed length 305 to be retracted from the slot 306.

The slot is also recessed within the tabular section to prevent a person from being able to squeeze the barbs together and remove the locking device by passing the tail back through the slot. A shoulder or collar may be added to make it more difficult to access the barbs at the slot position. As a further measure, a weak point may be positioned within the tail to ensure that the tail breaks off before the bards tear and allow removal of the locking device. The locking device according to this example is formed from a brightly coloured plastic which is molded as a single unit. The parallel voids within the second part 303 serve to allow the second part to fill more quickly and uniformly with liquid material during fabrication, to use less material than would otherwise be required and also to cool more uniformly whilst avoiding shrinkage problems. In order to fit this locking device to the scaffolding apparatus the barbed length

305 is fed into the top of a channel 20 and pulled through from the bottom of the channel 20 until the first part 300 sits completely within the channel 20. The barbed length 305 is then brought up past the outside of the collar 16 and fed through the slot

306 until tight. The barbs engaging with the slot 306 prevent the barbed length from being loosened. In order to remove the locking device, the barbed length can be cut.

Claims

1. A locking device for use with scaffolding apparatus, the scaffolding apparatus comprising:- a first pole having a projection; one or more further poles, for coupling to the first pole; and, a collar having an aperture through which the first pole may pass, the collar further comprising a channel through which the projection may pass, the channel forming part of the aperture, wherein the collar is adapted to be slidably mounted to the first pole such that it may only pass the projection when the projection is aligned with the channel; the apparatus being adapted such that, in use, the collar is slid past the projection of the first pole and further moved to an engagement position in which the first and further poles are fixed in relative orientation by engagement with the collar; and wherein the locking device is adapted in use to be coupled to the apparatus such that the collar is prevented from sliding past the projection.

2. A device according to claim 1, wherein at least a first part of the locking device is adapted to be fitted within the channel, the first part being of suitable dimensions so as to prevent the projection and the said first part coexisting in the channel.

3. A device according to claim 2, further comprising a second part, larger than the first, the second part being too large to fit within the channel.

4. A device according to claim 3, wherein at least the first part of the locking device is tapered.

5. A device according to any of the preceding claims, wherein at least part of the locking device is arranged in use so as to prevent relative alignment between the projection and the channel.

6. A device according to claim 5, wherein the collar of the scaffolding apparatus further comprises a surface adjacent to the channel and wherein the said part of the locking device for preventing relative alignment is adapted to be positioned in use between the said surface and the projection.

7. A device according to any of the preceding claims, wherein the locking device further comprises a-tamper-evident-part.-

8. A device according to any of the preceding claims, wherein the locking device comprises a resilient bung, having a diameter slightly larger than that of the channel, such that the bung can be forced into the channel.

9. A device according to claim 8, wherein the bung is formed from first and second parts, arranged end-to-end and joined by a relatively weak region therebetween.

10. A device according to claim 8 or claim 9, wherein the locking device further comprises an elongate plunger adapted to be driven into the bung and then deformed.

11. A device according to any of claims 1 to 7, wherein the locking device comprises a pin, such that, in use, the pin fits within the channel.

12. A device according to claim 11 , wherein the pin is tubular.

13. A device according to claim 11 , wherein the pin is solid or solid in part.

14. A device according to any of the preceding claims, further comprising a first fastening member and a second fastening member, the first and second fastening members being adapted to couple together so as to lock the locking device to the apparatus.

15. A device according to claim 14, wherein the first fastening member is a tail of a ratchet fastener and the second fastening member is a locking head of a ratchet fastener.

16. A device according to claim 14, wherein the first fastening member is a tail which is provided with one or more pairs of barbs, the barbs of each pair being located upon opposed sides of the tail.

17. A device according to claim 16, wherein the second fastening member comprises a part having a slot through which the tail of the first fastening member may only pass in one direction by the resilient deformation of the sides of the slot and/or the barbs.

18. A device according to claim 17, wherein the second part of the device has a tabular section within which is located the slot of the second fastening member.

19. A device according to claim 14, wherein the first fastening member is a wire of variable diameter and the second fastening member is a crimp.

20. A device according to claim 14, wherein the first and second fastening members are adapted to be glued or fused together.

21. A device according to any of claims 14 to 18, wherein one or each of the first and second fastening members is integral with the locking device.

22. A device according to any of claims 14 to 21 , wherein the first and second fastening members are adapted to form a closed loop when coupled together.

23. A device according to claim 14 and when dependent upon at least claim 11, wherein the first fastening member is a circumferential groove formed within an external surface of the pin, and the second fastening member is a clip for attachment to the collar, the clip having an aperture through which part of the pin may pass such that the groove may be aligned with the aperture, wherein the part of the pin which passes through the aperture is formed from a resilient material such that the said part of the pin may be passed through the aperture in the clip by deformation, and wherein the part of the pin forming the groove thereafter engages with the aperture edge to lock the pin within the channel.

24. A device according to any of the preceding claims, wherein the locking device is formed from a plastics material.

25. A device according to any of the preceding claims, wherein the locking device is formed from a metal:

26. A device according to any of the preceding claims, wherein the locking device is formed from a resilient material.

27. A device according to any of the preceding claims, wherein the locking device is adapted to be irreversibly coupled to apparatus.

28. A device according to any of the preceding claims, wherein the locking device is non-reusable.

29. A device according to any of the preceding claims, wherein, in use, the coupling device maintains the integrity of the apparatus.

30. A device according to any of the preceding claims, wherein, in use, the coupling device is a safety device.

31. A scaffolding system comprising:- a plurality of locking devices according to any of the preceding claims; a plurality of scaffolding apparatus, each apparatus comprising:- a) a first pole having a projection; b) one or more further poles, for coupling to the first pole; and, c) a collar having an aperture through which the first pole may pass, the collar further comprising a channel through which the projection may pass, the channel forming part of the aperture, wherein the collar is adapted to be slidably mounted to the first pole such that it may only pass the projection when the projection is aligned with the channel; each apparatus being adapted such that, in use, the collar is slid past the projection of the first pole and further moved to an engagement position in which the first and further poles are fixed in relative orientation by engagement with the collar; wherein each locking device is adapted in use to be coupled to the respective apparatus such that the collar is prevented from sliding past the projection.

32. An erected scaffolding system according to claim 31.