An end frame

Abstract

An end frame 1 for an access tower, the end frame comprises at least two stiles2, 3, substantially parallel to one another; a first spigot 10a rigidly secured to a first end of the first stile; and a

Description

FIELD The present invention relates to an end frame for an access tower, and an access tower comprising two or more end frames. The invention also relates to a floating spigot for an end frame. BACKGROUND An access tower comprises a plurality of structural components connected together to form a tower of a desired height, for a user(s) to scale the tower and work safely at height on the tower. A known access tower system comprises a plurality of identical end frames and a plurality of bracing members. Two end frames are arranged on the ground spaced apart from, and roughly parallel to, one another. The end frames are then joined together in that configuration using a plurality of bracing members (usually diagonally), to form a first level of the access tower, being roughly rectangular in plan view. A panelZboard(s) may extend between the end frames to create a work platform for a user to stand on. Additional levels of the access tower are formed by securing further end frames on the top of each of the end frames of the first level, before joining those further end frames together with bracing members, to form a second level. A panelZboard(s) may extend between the end frames of the second level to create another work platform for a user to stand on. Further levels may be formed in the same way, to create an access tower of a predetermined height. The end frames may comprise ladder sections to allow a user to scale the tower. Alternatively or additionally, the work platform provided at each level may comprise an access opening, through which a user may pass using a ladder. WheelsZcastors may be provided at the bottom of the tower. Additional stabilisers may be secured for access towers over a predetermined height. Each end frame comprises two stiles, to be arranged vertically in use, and the upper end of each stile is provided with a spigot. The lower end of each stile defines, or is provided with, a socket to receive the spigot of an end frame arranged beneath in use. In a known end frame, each spigot is rigidly secured to the upper end of each of the respective stiles, referred to herein as a ‘rigid spigot’. When multiple end frames are secured together, the resulting access tower affords a suitable level of rigidity. There is a need for the distance between the longitudinal axes of the rigid spigots to match the distance between the longitudinal axes of the stiles / sockets, to aid assembly of the end frames. This necessitates narrow tolerances when manufacturing the end frames. In use, particularly on construction sites, the end frames will sustain wear and tear. Debris may be collected in the sockets and / or on the spigots, the sockets / spigots may be damaged, misaligned or otherwise have building material deposited on / in them. After several uses or after sustaining damage, the rigid spigots of an end frame may not be easily receivable in the end of a stile of an adjacent end frame. If a user forces two end frames together, for example with a blunt implement, this may further damage the spigot, socket and / or frame, and may hinder or prevent disassembly; and may render the end frame no longer serviceable. An alternative to using rigid spigots is to provide the end frame with two floating spigots, wherein the spigots are not rigidly secured to the upper end of either of the stiles. The distance between the longitudinal axes of the two floating spigots is then adjustable during assembly, to account for any variation in the distance and / or alignment between the longitudinal axes of the sockets into which the spigots are received. Floating spigots may also allow relative angular misalignment between the longitudinal axes of the spigots, such that they are no longer parallel. An unintended consequence of providing two floating spigots is that they prevent a rigid connection being formed between two adjoined end frames. An access tower comprised of end frames having two floating spigots may not have the structural rigidity expected by users, and have an unacceptable amount of play. A lack of rigidity may be exacerbated in taller access towers, rendering them unusable or at least undermining a user’s confidence in the safety of the tower. The present invention seeks to provide an improved end frame. BRIEF DESCRIPTION OF THE INVENTION The present invention provides an end frame for an access tower, comprising: at least two stiles, substantially parallel to one another; a first spigot rigidly secured to a first end of the first stile; and a second spigot secured to a first end of the second stile with a floating connection, to allow the second spigot to move relative to the second stile. In at least one embodiment, each stile has a second end configured to receive, in use, a respective spigot of another end frame. In at least one embodiment, the longitudinal axis of the first spigot is substantially coaxial with the longitudinal axis of the first stile. In at least one embodiment, the second spigot is secured to the first end of the second stile so as to allow movement in a plane perpendicular to the longitudinal axis of the second stile. In at least one embodiment, the extent of said perpendicular movement is limited to within a predetermined range. In at least one embodiment, the second spigot is configured to be movable along a first axis X up to a distance A from the longitudinal axis of the second stile, and movable along a second axis Y up to a distance B from the longitudinal axis of the second stile, wherein the longitudinal axis of the second stile, and the axes X and Y are mutually perpendicular, and B is less than A. In at least one embodiment, the second spigot is secured to the first end of the second stile so as to allow the second spigot to rotate about an axis that is perpendicular to the longitudinal axis of the second stile. In at least one embodiment, the extent of rotation is limited to within a predetermined range. In at least one embodiment, the second spigot is mounted on a pin passing perpendicularly through the first end of the second stile. In at least one embodiment, the second spigot is configured to translate along and / or rotate about the pin. In at least one embodiment, the first and second spigots have substantially the same outer diameter, and the lower end of each of the stiles comprises a socket having substantially the same internal diameter, to receive a respective spigot therein in use. In at least one embodiment, the first and second spigots are configured to be received in the lower end of a respective stile of another end frame with an interference fit. In at least one embodiment, the second spigot comprises a first section and a second section, the first section arranged to extend from the first end of the second stile to define a boss, and the second section arranged to be received in the first end of the second stile. In at least one embodiment, the cross-sectional area of the second section of the second spigot is smaller than the cross-sectional area of the first section of the second spigot. In at least one embodiment, the first section has a substantially circular outer surface, and the second section has a non-circular outer surface. In at least one embodiment, the stiles are joined to one another by at least one cross bar. The present invention provides an access tower comprising at least two end frames as described, wherein each spigot of a first end frame is received in the lower end of the respective stile of a second end frame. The present invention provides a floating spigot arrangement for an end frame of an access tower, comprising: a first section defining a boss, configured to be received in a socket of an adjacent end frame in use, a second section to be received in a first end of a first stile of the end frame in use, wherein the floating spigot arrangement is mountable on a pin passing through the first end of the first stile, to allow the floating spigot to translate along the pin to a predetermined extent, but to limit rotation of the floating spigot arrangement about the pin. In at least one embodiment, wherein the first section is substantially cylindrical, and the second section is non-cylindrical. In at least one embodiment, wherein the diameter of the second section along the X axis is smaller than the diameter of the second section 66 along the Y axis, wherein the longitudinal axis of the second stile, and the axes X and Y are mutually perpendicular. BRIEF DESCRIPTION OF THE FIGURES In order that the present disclosure may be more readily understood, preferable embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, in which: FIGURE 1 illustrates an end frame for an access tower; FIGURE 2 illustrates how an end frame is secured to another end frame arranged beneath; FIGURE 3 illustrates a known rigid spigot; FIGURE 4 illustrates a known floating spigot; FIGURES 5 and 6 show a cross-section of a known floating spigot, viewed through a horizontal plane; FIGURE 7 illustrates an axial cross-sectional view of the floating spigot of figures 5 and 6, having been rotated about a pin; FIGURE 8 illustrates a part of an end frame embodying the present invention; FIGURE 9 illustrates a cross-section, along a horizontal plane, of a floating spigot embodying the present invention; and FIGURE 10 illustrates a cross-section, along a horizontal plane, of another floating spigot embodying the present invention. DETAILED DESCRIPTION OF THE DISCLOSURE Figure 1 illustrates an end frame 1 for an access tower. The end frame 1 comprises a pair of stiles 2, 3, which are arranged substantially parallel to one another. The stiles 2, 3 are secured to one another by cross bars 4, 5. Although two cross bars 4, 5 are shown, there may be more cross bars. The cross bars 4, 5 are substantially perpendicular to the stiles 2, 3. In use, the stiles 2, 3, are arranged substantially vertically, and so the cross bars 4, 5, are arranged substantially horizontally. In the end frame 1 illustrated in Figure 1, a ladder section 6 is incorporated into the end frame 1, to allow a user to scale an access tower constructed of the end frames 1 in use. The ladder section 6 may provide additional rigidity to the end frame 1. Additional strengthening ribs 7 may be provided between the cross bars 4, 5 and the stiles 2, 3, to provide additional rigidity. Spigots 10a, 10b, are provided at the first end of the respective stiles 2, 3. The second end of the stiles 2, 3, opposite the first end, defines or comprises a socket 11a, 11b. According to a known arrangement, the end frame 1 is arranged such that the spigots 10a, 10b are provided at the upper end of the end frame 1, and the sockets 11a, 11b are provided at the lower end of the end frame 1. However, it is to be appreciated that the end frame 1 would also function if inverted. Figure 2 illustrates two end frames 1, 100 being assembled together in use, to form an access tower. A user positions the end frame 1 above a further end frame 100. The sockets 11a, 11 b of the end frame 1 are arranged above the respective spigots 110a, 110b, of the second end frame 100 beneath. The end frame 1 is then manoeuvred into place such that the spigots 110a, 110b are received into the sockets 11a, 11b. The weight of the end frame 1 may be sufficient so as to cause the spigots 110a, 110b to be progressively received into the sockets 11a, 11b. Additionally or alternatively, the user may apply a downward force onto the end frame 1 so as to ensure proper engagement with the end frame 100. Figure 3 illustrates a rigid spigot 50. The top of the spigot 50 may comprise a bevelled section 51, to aid in the alignment of the spigot when initially received in a socket. The main body 52 of the spigot 50 may be substantially cylindrical. This is not essential. The spigot 50 comprises a shoulder 53, against which the mouth of a socket may rest when the spigot 50 is received in a socket of another end frame in use. Figure 4 illustrates a known floating spigot 60. As with the rigid spigot 50 shown in Figure 3, the floating spigot 60 comprises a bevelled section 61, having substantially the same function and / or dimensions as the bevelled section 51 of the rigid spigot 50. The floating spigot 60 further comprises a main body 62 which, as with the rigid spigot, may be substantially cylindrical. Furthermore, as with the rigid spigot, the floating spigot 60 further comprises a shoulder 63. As discussed above, known end frames, which may substantially comprise the end frame 1 illustrated in Figures 1 and 2, may comprise either both rigid spigots 50, or both floating spigots 60. The disadvantages of using only rigid spigots 50, or using only floating spigots 60, are discussed above. Figures 5 to 7 further illustrate the issues with a known floating spigot 60. Figures 5 and 6 show a cross-section of the floating spigot 60, along a horizontal plane, passing through pin 65 shown in figure 4. The pin 65 is provided through the upper end of the stile 2, 3. A collar 64 may be provided at the top of the stile 2, 3, for additional rigidity, and to provide a structure through which the pin 65 is received. The pin 65 extends across the diameter of the stile 2, 3 (and / or collar 64). The main cylindrical body 62 of the floating spigot comprises two diametrically opposed apertures, through which the pin 65 is received. In Figures 5 and 6, the inner dark circle 62 denotes the outer diameter of the main cylindrical body 62 of the floating spigot 60. It will be noted that this is smaller than the inner diameter of the stile 2, 3, denoted by the lighter line. Consequently, in use, the floating spigot 60 is permitted to translate along the pin 65, allowing a predetermined movement of the floating spigot 60 in a plane which is perpendicular to the longitudinal axis of the stile 2, 3. Figure 5 illustrates the maximum extent of the translation in one direction, and Figure 6 shows the floating spigot 60 roughly centralised in the stile 2, 3. It will be appreciated, although not illustrated, that the floating spigot 60 may translate along the pin 65 in the opposite direction to that shown in Figure 5, thereby defining the full range of translational movement possible. This translation of the floating spigot 60 along the pin 65 provides the “floating” arrangement, wherein the relative distance between two spigots of an end frame may be adjusted. It will be appreciated that the pin 65 of one floating spigot should be substantially coaxial with the pin 65 of another floating spigot on the end frame, such that the floating spigots may move towards and away from one another, to accommodate play. The consequence of the cylindrical body 62 of the floating spigot 60 being less than the inner diameter of the stile 2, 3 is that the floating spigot 60 may also rotate about the longitudinal axis of the pin 65, as shown in Figure 7. Although this additional movement about the axis, as well as along the axis of the pin, may be useful in aligning end frames, it may also provide an unwanted level of play, and thus a lack of rigidity, in the access tower when assembled. The present invention relates to an end frame having both a rigid spigot and a floating spigot in combination. Consequently, the floating spigot provides a suitable level of adjustment when assembling end frames, and the use of the rigid spigot ensures adequate rigidity in the access tower. Accordingly, the present invention provides an end frame for an access tower, comprising: at least two stiles, substantially parallel to one another; a first spigot rigidly secured to a first end of the first stile (referred to herein as a rigid spigot); and a second spigot secured to a first end of the second stile with a floating connection (referred to herein as a floating spigot), to allow the second spigot to move relative to the second stile. The second end of each stile 2, 3 may define a socket, or be provided with an insert which defines a socket. Preferably, the stiles 2, 3 are elongate and of substantially the same cross-section. In at least one embodiment, they may be formed by extruding aluminium. The outer diameter of the first spigot may be substantially the same as the outer diameter of the second spigot. Likewise, the cross-sectional area of the first spigot may be substantially identical to that of the second spigot. The socket defined by or provided at the second end of the first stile may be of substantially the same dimension / cross area as the socket provided by or at the second end of the second stile. The internal diameter of the socket may be the same or slightly less than the outer diameter of the spigots, such that the spigots may be receivable in the sockets with a substantially interference fit. Additional tightening or securing means may be provided in use, to secure / lock the end frames 1 together. Nevertheless, it is preferred that no additional features or tools are needed, so as to aid the assembly / disassembly of an access tower in use. Figure 8 schematically illustrates the upper end of an end frame 1 embodying the present invention, comprising a rigid spigot 10a, and a floating spigot 10b. Figure 9 illustrates a floating spigot arrangement 160 embodying the present invention, for an end frame of an access tower. The floating spigot arrangement 160 comprises a first section defining a boss, configured to be received in a socket in use. The first section may be substantially similar to that of the floating spigot illustrated in figures 4-6. The floating spigot arrangement further comprises a second section 66, to be received the first end of a stile 2, 3. As with the floating spigot 60 shown in Figures 4 to 6, the floating spigot 160 arrangement of Figure 9 is mountable on a pin 65 passing through the first end of the stile 2, 3, to allow the floating spigot 160 to translate along the pin 65 to a predetermined extent. However, as will be seen in Figure 9, the cross-section of the second section 66 of the floating spigot 160 (not visible in figure 8) differs to that shown in Figures 5 and 6, by being non-circular. Consequently, the gap between the second section 66 and the inner surface of the stiles 2, 3 along the X direction is greater than the gap between the second section 66 and the inner diameter of the stiles 2, 3 in the Y direction. The benefit of this arrangement is that the floating spigot 160 is still allowed to translate along the pin 65, but excessive rotation of the floating spigot arrangement about the pin 65 is restricted, due to the reduced gap between the wall of the second section and the inner diameter of the spigot 2, 3. Consequently, the floating spigot 160 shown in Figure 9 may rotate about the axis of the pin 65 to a lesser extent than that illustrated in Figure 7 of the known floating spigot arrangement. The diameter of the second section 66 along the X axis is smaller than the diameter of the second section 66 along the Y axis, wherein the longitudinal axis of the second stile, and the axes X and Y are mutually perpendicular. Figure 10 illustrates another floating spigot 260 embodying the present invention. In this embodiment, the second section comprises a sleeve 67 to receive the pin 65, and fins 67 which extend in the direction of the longitudinal axis of the floating spigot, away from the first section. The length of the sleeve 67 is less than the distance between the outer edges of the fins 67. Consequently, the floating spigot 260 is translatable along the pin to a predetermined extent, but excessive rotation of the floating spigot 260 is restricted. Although in the illustrated embodiment, there is a pair of stiles 2, 3, this is not essential. There may be more than two stiles. An end frame may have three stiles. The stiles may be co-planar with one another, forming a planar end frame, or they may be non-co-planar, forming a non-planar end frame. In an embodiment having three or more stiles, one stile may have a rigid spigot and the other stiles may have a floating spigot. When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components. The invention may also broadly consist in the parts, elements, steps, examples and / or features referred to or indicated in the specification individually or collectively in any and all combinations of two or more said parts, elements, steps, examples and / or features. In particular, one or more features in any of the embodiments described herein may be combined with one or more features from any other embodiment(s) described herein. Protection may be sought for any features disclosed in any one or more published documents referenced herein in combination with the present disclosure. Although certain example embodiments of the invention have been described, the scope of the appended claims is not intended to be limited solely to these embodiments. The claims are to be construed literally, purposively, and / or to encompass equivalents.

Claims

1. An end frame for an access tower, comprising:at least two stiles, substantially parallel to one another;a first spigot rigidly secured to a first end of the first stile; anda second spigot secured to a first end of the second stile with a floating connection, to allow the second spigot to move relative to the second stile.

2. An end frame according to claim 1, wherein each stile has a second end configured to receive, in use, a respective spigot of another end frame.

3. An end frame according to any preceding claim, wherein the longitudinal axis of the first spigot is substantially coaxial with the longitudinal axis of the first stile.

4. An end frame according to any preceding claim, wherein the second spigot is secured to the first end of the second stile so as to allow movement in a plane perpendicular to the longitudinal axis of the second stile.

5. An end frame according to claim 4, wherein the extent of said perpendicular movement is limited to within a predetermined range.

6. An end frame according to claim 4 or 5, wherein the second spigot is configured to be movable along a first axis X up to a distance A from the longitudinal axis of the second stile, and movable along a second axis Y up to a distance B from the longitudinal axis of the second stile, wherein the longitudinal axis of the second stile, and the axes X and Y are mutually perpendicular, and B is less than A.

7. An end frame according to any preceding claim, wherein the second spigot is secured to the first end of the second stile so as to allow the second spigot to rotate about an axis that is perpendicular to the longitudinal axis of the second stile.

8. An end frame according to claim 7, wherein the extent of rotation is limited to within a predetermined range.

9. An end frame according to any preceding claim, wherein the second spigot is mounted on a pin passing perpendicularly through the first end of the second stile.

10. An end frame according to claim 9, wherein the second spigot is configured to translate along and / or rotate about the pin.

11. An end frame according to any preceding claim, wherein the first and second spigots have substantially the same outer diameter, and the lower end of each of the stiles comprises a socket having substantially the same internal diameter, to receive a respective spigot therein in use.

12. An end frame according to any preceding claim, wherein the first and second spigots are configured to be received in the lower end of a respective stile of another end frame with an interference fit.

13. An end frame according to any preceding claim, wherein the second spigot comprises a first section and a second section, the first section arranged to extend from the first end of the second stile to define a boss, and the second section arranged to be received in the first end of the second stile.

14. An end frame according to claim 13, wherein the cross-sectional area of the second section of the second spigot is smaller than the cross-sectional area of the first section of the second spigot.

15. An end frame according to claim 13 or 14, wherein the first section has a substantially circular outer surface, and the second section has a non-circular outer surface.

16. An end frame according to any preceding claim, wherein the stiles are joined to one another by at least one cross bar.

17. An access tower comprising at least two end frames according to anypreceding claim, wherein each spigot of a first end frame is received in the lower end of the respective stile of a second end frame.

18. A floating spigot arrangement for an end frame of an access tower, comprising:a first section defining a boss, configured to be received in a socket of an adjacent end frame in use,a second section to be received in a first end of a first stile of the end frame in use,wherein the floating spigot arrangement is mountable on a pin passing through the first end of the first stile, to allow the floating spigot to translate along the pin to a predetermined extent, but to limit rotation of the floating spigot arrangement about the pin.

19. A floating spigot arrangement according to claim 18, wherein the first section is substantially cylindrical, and the second section is non-cylindrical.

20. A floating spigot arrangement according to claim 18 or 19, wherein the diameter of the second section along the X axis is smaller than the diameter of the second section 66 along the Y axis, wherein the longitudinal axis of the second stile, and the axes X and Y are mutually perpendicular.

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