EP1972737A2

EP1972737A2 - Scaffold arrangement

Info

Publication number: EP1972737A2
Application number: EP08001216A
Authority: EP
Inventors: Mark Taylor
Original assignee: SGB Services Ltd
Current assignee: Harsco Infrastructure Services Ltd
Priority date: 2007-03-23
Filing date: 2008-01-23
Publication date: 2008-09-24
Anticipated expiration: 2028-01-23
Also published as: EP1972737A3; GB0705669D0; GB2447710B; EP1972737B1; EP1972737B8; GB2447710A; GB2447710C

Abstract

A scaffold arrangement (1) comprising a scaffold component (2) and a support unit (3) for releasably supporting the scaffold component in an operative position on a scaffold assembly or building, the support unit (3) comprising a mounting portion for fixedly mounting the support unit to said scaffold assembly, a supporting member for seating a first part of the scaffold component, and a releasable locking member moveable to a locking position for locking the scaffold component to the support unit, the arrangement being such that when the scaffold component (2) is seated on the supporting member in said operative position, and the locking member is in said locking position, the locking member is spaced immediately below a second part of the scaffold component (2) and acts as a back-up supporting member for arresting uncontrolled downward movement of the scaffold component (2) relative to the support unit (3).

Description

Description of Invention

The present invention relates to a scaffold arrangement for releasably supporting a scaffold component in an operative position on a scaffold assembly, in particular for releasably supporting a climbing scaffold screen on a scaffold assembly, and to a support unit for use in such an arrangement.
Depending upon the particular scaffolding application, it may be desirable to support auxiliary scaffold components on a main scaffold assembly, for example alongside a working platform of the main scaffolding assembly, or directly on a building itself.
An example of such an auxiliary scaffold component is a so-called "climbing" scaffold screen, which may be supported on the outside of a scaffold assembly to protect individuals on an associated working platform of the scaffold assembly. Such scaffolding screens find particular application in the context of very tall scaffold assemblies, for example those used during "high-rise" construction.
It is strongly desirable for scaffold screens and certain other such scaffold components be releasably supported on the main scaffold assembly or building so that, when an extra working "layer" is added to the scaffold assembly, the scaffold screen can be disengaged from the scaffold assembly or building and raised (for example by crane or hydraulic lifts) up to the level of the new working platform. The screen may thus "climb" up the scaffold assembly or building as the height of the scaffold assembly or building is progressively increased.
At the same time, scaffold screens and other such scaffold components should be supported on the main scaffold assembly or building in a secure manner, so that the risk of accidental disengagement of the scaffold component is minimised, whilst preferably still allowing for relatively straightforward deliberate disengagement when it is desired to move the scaffold component.
In addition, it is often desired that an arrangement for supporting an auxiliary scaffold component such as a scaffold screen be provided with safety features which minimise the chance of uncontrolled downward movement or "slippage" of the scaffold component relative to the supporting scaffold assembly or building, for example due to failure of the primary supporting mechanism. The dangers of uncontrolled free-fall of scaffold components are manifest; however, even a small uncontrolled downward movement could be disastrous, particularly if the scaffold screen or the like incorporates a working sub-platform or walkway high above ground.
With the above in mind, it will be appreciated therefore that there are a number of technical considerations which need to be taken into account when designing arrangements for supporting such scaffolding components. Indeed, a well-considered design may require a very delicate "balancing act" between competing technical considerations (which might also include common, less specific technical considerations such as, for example, ease of technical operation and simplicity of construction).
It is an object of the present invention to seek to provide an improved scaffold arrangement.
According to the present invention, there is provided a scaffold arrangement comprising a scaffold component and a support unit for releasably supporting the scaffold component in an operative position on a scaffold assembly or building, the support unit comprising a mounting portion for fixedly mounting the support unit to said scaffold assembly, a supporting member for seating a first part of the scaffold component, and a releasable locking member moveable to a locking position for locking the scaffold component to the support unit, the arrangement being such that when the scaffold component is seated on the supporting member in said operative position, and the locking member is in said locking position, the locking member is spaced immediately below a second part of the scaffold component and acts as a back-up supporting member for arresting uncontrolled downward movement of the scaffold component relative to the support unit.
Preferably, the locking member is a slidable locking member mounted for sliding movement between a retracted position and said locking position.
Conveniently, the arrangement is provided with a locking element for locking the locking member to another part of the support unit, to prevent sliding movement of the locking member, but only if the locking member is correctly located in the locking position.
Preferably, the locking element is in the form of a rigid locking pin, the arrangement being configured to allow insertion of the rigid locking pin through both the locking member and another part of the support unit to prevent relative sliding movement therebetween, but only when the locking member is correctly located in the locking position.
Conveniently, the locking member is slidably mounted on the supporting member and the supporting member is pivotally connected to the mounting portion such that, when the mounting portion is fixedly mounted on the scaffold assembly or building, the supporting member may be pivoted between a supporting position, wherein the supporting member projects laterally from the scaffold assembly or building, and a stowed position, wherein the supporting member is contained within the footprint of the scaffold assembly or building.
Advantageously, the arrangement is configured to allow insertion of the locking pin through both the locking member and another part of the support unit other than the supporting member, such that the locking pin additionally locks the supporting member in its supporting position.
Preferably, the support unit is provided with a fixed catch member, the catch member and sliding locking member co-operating with one another to form a latch wherein, when the supporting member is in said stowed position, the locking member may be slid to said retracted position to engage the catch member and retain the supporting member in the stowed position.
Optionally, in said supporting position the supporting member extends upwardly such that the locking member may slide downwardly to said retracted position under its own weight, thereby automatically engaging the catch member to retain the supporting member in the stowed position.
Preferably, the catch member is positioned to abut against the locking member and thereby slide the locking member relative to the supporting member as the latter is pivoted from the supporting position towards the stowed position, wherein the locking member is prevented from dropping to the retracted position, and thereby interfering with the pivoting of the supporting member, until such time as the supporting member reaches the upwardly extending stowed position.
Conveniently, the support unit comprises a pair of generally parallel mounting elements, the supporting member being pivotally mounted between the mounting elements, and parallel with the mounting elements, the mounting elements being configured to receive the locking pin therethrough such that the locking pin extends between the mounting elements for preventing the supporting member from returning to the supporting position from the stowed position.
Optionally, the support unit comprises a pair of generally parallel beams, the supporting member being pivotally mounted between the beams, and parallel with the beams, and the catch member being in the form of a catch plate extending laterally between the beams.
In a preferred embodiment, the first and second parts of the scaffold component are in the form of two generally parallel support bars, the support bars being arranged on the scaffold component so as to be generally horizontal when the scaffold component is in said operative position, the supporting member comprising an upturned hook portion for receiving and seating a lower one of the support bars with the scaffold component in the operative position, the locking member being in the form of an elongate, slidable locking arm mounted to the supporting member for sliding movement to said locking position, in which the locking arm projects between the lower support bar and the other, upper support bar and is spaced immediately below the upper support bar.
Preferably, the scaffold component is a scaffold screen.
According to another aspect of the present invention there is provided a support unit for use in the scaffold arrangement according to the present invention, the support unit comprising a mounting portion for fixedly mounting the support unit to said scaffold assembly, a supporting member for seating the first part of the scaffold component with the scaffold component in an operative position, and a slidable locking member moveable from a retracted position to a locking position for locking the scaffold component to the support unit, the locking member having sufficient load-bearing capability for arresting uncontrolled downward movement of the scaffold component from its operative position when the locking member is in the locking position.
So that the invention may be readily understood, embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIGURE 1 shows a perspective view of one embodiment of a scaffold arrangement in accordance with the present invention;
FIGURE 2 shows a perspective of the scaffold arrangement of Figure 1 in a different configuration;
FIGURE 3 shows a perspective view of an embodiment of a support unit for use in the scaffold arrangement of Figure 1;
FIGURE 4 shows a further perspective view of the support unit shown in Figure 3, in a second configuration;
FIGURE 5 shows a yet further perspective view of the support unit shown in Figure 3, in a third configuration.

Figures 1 and 2 illustrate a scaffold arrangement 1 comprising a scaffold component 2 and a support unit 3 for releasably supporting the scaffold component 2.
A supporting member 4 (partly obscured in Figures 1 and 2, but shown more clearly in Figure 3) is mounted at one end of the support unit and a locking member in the form of a slidable locking arm 5 is in turn mounted on the supporting member 4. The slidable locking arm 5 is in a retracted position in Figures 1 and 2 and is prevented from sliding movement toward the scaffold component by means of a locking pin 6, the precise operation of which will be described in more detail below.
A pair of guide members 7 are also provided on the support unit 3, either side of the hooked supporting member 4, for guiding controlled vertical sliding movement of the scaffold component 2 in a manner known per se, as may be desirable when the scaffold component is attached to a captive "climbing" scaffold screen.
In use the support unit 3 is fixedly secured to a scaffold assembly or building (not shown) in the generally horizontal orientation shown in Figures 1 and 2, with the hooked supporting member 4 projecting laterally outwardly beyond the "footprint" of the scaffold assembly.
The scaffold component 2 comprises a pair of "back-to-back" C-section beams 8 (i.e. arranged with the C-sections facing outwardly), each beam 8 incorporating an array of machined holes arranged at a standard pitch. A pair of support bars in the form of bolts 9a, 9b are secured between the C-section beams 8 in the manner of rungs on a ladder, the bolts engaging adjacent machined holes on each C-section beams 8 such that the bolts 9a, 9b are spaced apart a distance corresponding to the pitch of the machined holes.
The scaffold component 2 may be fixedly attached to, or integrally formed as part of, a larger scaffold component such as a scaffold screen or the like. For large scaffold components, it is envisaged that the support unit 3 may be used in conjunction with similar or different supports in order to provide primary support for the full load of the scaffold component.
In order to releasably support the scaffold component 2 on the support unit 3 (and hence on the scaffold assembly to which the support unit 3 is typically secured) the scaffold component 2 is orientated in its operative position with the C-section beams 8 extending generally vertically, and the lower support bar 9a is then seated on the hooked supporting member 4 (it should be noted here that the guide members 7 can be pivoted outwardly from the supporting member 4 so as not to interfere with the C-section beams 8 as the lower support bar 9a is being seated, before being pivoted back to their guiding position shown in Figure 1).
Once the lower support bar 9a has been seated on the supporting member 4 the locking pin 6 can be removed and the locking arm 5 subsequently slid from the retracted position shown in Figure 1 to a locking position, shown in Figure 2, whereby the locking arm 5 projects between the lower support bar 9a and the upper support bar 9b. The arm 5 can then be secured in the locking position by means of the locking pin 6, as described in more detail below.
In the locking position, the locking arm 5 performs a "dual-action". Thus, the locking arm 5 co-operates with the hooked supporting member to secure the lower support bar 9a, and hence the scaffold component 2, to the support unit 3, whilst, at the same time, the locking arm 5 is spaced immediately below the upper support bar 9b so as to act as a back-up supporting member for arresting uncontrolled downward movement of the scaffold component, relative to the support unit 3, in an emergency situation. For example, should the lower bolt shear off from the scaffold component 2 for whatever reason, such that the scaffold component 2 starts to accelerate downwardly under its own weight (assuming there are no other remaining supports supporting the weight of the scaffold component), then the upper support bar 9b will very quickly impact the locking arm 5 to help arrest downward movement of the scaffold component 2. The upper support bar 9b will necessarily impact the locking arm 5 before it would otherwise have impacted the supporting member 4.
Further features of the scaffold arrangement and its operation will now be described in more detail with reference to a support unit in isolation.
Thus Figures 3 to 5 illustrate a support unit 3a for use in the scaffold arrangement 1. The support unit 3a is identical in most respects to the support unit 3 forming part of the scaffold arrangement 1 and may be readily interchanged with support unit 3 in the scaffold arrangement 1, without modification to the scaffold component 2. As such, like features have been labelled with like reference numerals as appropriate.
The support unit 3a comprises a pair of elongate C-section mounting elements 10 arranged "back-to-back" (in similar manner to the C-section beams 8) and extending generally parallel with one another from a mounting portion, in the form of a right-angle mounting bracket 11, to define a channel 12 therebetween. A base plate (not shown) is welded to the underside of the mounting elements 10 to act as a brace.
The mounting bracket 11 may be used to fixedly secure the support unit 3 to a scaffold assembly in any conventional manner (here, it should be noted that the support unit 3a differs only slightly from support unit 3 in that support unit 3 is provided with a pair of mounting "brackets" (labelled 11a in Figure 1), rather than a single right-angle mounting bracket 11. The particular form of mounting arrangement is not an essential part of the present invention, suffice to say that the support unit 3, 3a comprises a mounting portion for fixedly securing the support unit to a scaffold assembly in conventional manner). The present embodiment is described with reference to attachment to a scaffold assembly, but it should be understood that the support unit 3a might equally be attached to a building in conventional manner.
The supporting member 4, which is somewhat irregular in shape (as will be particularly appreciated by referring to Figure 5), comprises a pair of identical outer plates 4a defining an upturned hook portion 4b, and a slide-bearing plate 4c fixedly sandwiched between the outer plates 4a and welded to the outer plates 4a to form a unitary body. The slide-bearing plate 4c can be thought of as being identical in shape to the outer plates 4a, but with the upper section removed, whereby the outer plates 4a define the walls of a narrow channel 13 (Fig 4) running along the top of the supporting member 4 and a corresponding notch 14 at the tip of the hook portion 4b.
Corresponding horizontal slots 15 are cut out of the respective regions of the outer plates 4a defining the walls of the narrow channel 13.
The supporting member 4 is aligned lengthways within the channel 12, between the mounting elements 10, and is pivotally mounted to the mounting elements 10 at a pivot point (not shown) for pivoting movement in a plane parallel with the mounting elements 10 (see Figure 5).
Figure 3 shows the supporting member 4 in its supporting position, resting on a stop 16 (best shown in Figure 5) which extends across the channel 12, between the mounting elements 10. In this position, the supporting member 4 sits generally parallel with the mounting elements 10, with the hook portion 4b projecting out beyond the ends of the mounting elements 10 and the walls of the channel 13 standing proud above the mounting elements 10.
The elongate locking arm 5 is mounted within the channel 13 for sliding movement along the channel 13. The handle is provided with a handle portion 17 to allow manual sliding movement.
A clearance hole 18 is formed through the rear end of the locking arm (furthest from the hook portion 4b), the clearance hole 18 being dimensioned to receive therethrough the locking pin 6 in a close-fit. Additionally, a shallow depression 19 is provided along the top edge of the locking arm 5 at the front end of the locking arm 5 (nearest the hook portion 4b), the depression 19 being positioned to be located directly below the upper bolt when the scaffold component is releasably supported on the support unit 3a in an operative position and further being dimensioned to mate with the surface of the (cylindrical) upper bolt 9b should the upper bolt 9b drop onto the locking arm in an emergency as described above.
Lugs 5a (of which only one is visible in Figure 4) are provided on opposite sides of the locking arm 5, which respectively engage with the slots 15 formed in the walls of the channel 13 to allow sliding movement of the locking arm 5 between a fully retracted position, wherein the lugs 5a engage with the rear end of the slots 15, and a locking position, wherein the lugs 5a engage with the front end of the slots 15.
Still referring to figures 3 and 4, the support unit 3a is further provided with a pair of locking barrels 20 mounted directly opposite one another on the mounting elements 10, either side of the supporting member 4 and alongside the slots 15 (when the supporting member 4 is in the supporting position). Each locking barrel 20 is dimensioned to receive the locking pin 6 therethrough and positioned to align with the clearance hole 18 when the locking arm 5 is in the locking position shown in Figure 4.
It will be appreciated, referring to Figures 3 to 5, that the locking pin 6 acts as "multi-function" locking element, as follows:
Firstly, the locking pin 6 may function to lock the locking arm 5 to prevent sliding of the locking arm 5 relative to the supporting member 4. Thus, in the fully retracted position shown in Figure 3, the rear end of the locking arm 5 projects rearwardly beyond the end of the channel 13, and the locking pin may thus be inserted through the clearance hole 18 in the rear end of the locking arm 5, in the manner illustrated in Figure 1, to lock the locking arm in the fully retracted position. When the locking pin is removed, the locking arm is free to slide to the locking position shown in Figure 4, and in this position, the locking pin 6 can then be inserted through the locking barrels 20 and aligned clearance hole 18 (via slots 15), thereby locking the locking arm in the locking position.
At the same time, it will be appreciated that locking the locking arm 5 in the locking position in the above described manner also serves both to lock the supporting member 4 in the supporting position, as well as to locate the locking arm 5 accurately in the locking position (it being understood that if the locking arm 5 is not accurately located in the locking position then the clearance hole 18 will not be aligned with the locking barrels and insertion of the locking pin will not be possible).
When it is desired to pivot the supporting member upwardly away from the supporting position toward a stowed position, wherein the hook portion 4b no longer projects laterally beyond the end of the mounting elements 10, then the locking pin 6 may be removed and, once the lower edge of the supporting member 4 clears the locking barrels 20 (as in Figure 5), the locking pin 6 may be re-inserted through the locking barrels 20 to act as a temporary stop preventing the supporting member 4 from returning to its supporting position shown in Figure 3.
Similarly, when it is desired to controllably slide the scaffold component 2 upwards immediately adjacent the scaffold assembly, as may be the case if the scaffold component 2 is a "climbing" scaffold screen, the locking pin 6 may be removed to allow free pivoting movement of the supporting member 4 so as not to inhibit upwards movement of the scaffold component 2 by obstructing lower parts of the scaffold component.
In accordance with a further aspect of the present invention, the support unit 3a is provided with a catch member in the specific form of a catch plate 21, best shown in Figure 5, which extends across the channel 12 perpendicular the mounting elements 10.
The catch plate 21 co-operates with the locking arm 5 to form a latch for retaining the supporting member 4 in a stowed position.
Thus referring to Figure 5, it will be appreciated that if the supporting member 4 is rotated to a substantially vertical position (i.e. extending substantially vertically upwardly from the mounting elements 10) and the locking arm 5 is subsequently moved downwardly to its fully retracted position, the locking arm 5 may engage with the rear side of the catch plate 21 to prevent pivoting movement of the supporting member 4 back towards the supporting position until such time as the locking arm 5 is moved upwardly to release the latching-action.
Whilst the locking arm 5 may be held away from the fully retracted position until such time as the supporting member 4 is in the vertical stowed position (in order to prevent the locking arm interfering with the catch plate 21 before the supporting member 4 reaches the stowed position) it is preferred that the catch plate 21 be positioned such that the locking arm 5 and catch plate co-operate to provide an "automatic" latching action. Thus, referring to Figure 5, it will be appreciated that, due to the position of the catch plate 21, the catch plate 21 will abut against the locking arm 5 as the supporting member 4 is pivoted towards the stowed position, thus causing the locking arm 5 to progressively slide towards the hook portion 4b with progressive movement of the supporting member 4 towards the vertical stowed position. As the supporting member 4 approaches the stowed position, the locking arm 5 will eventually drop down on the rear side of the catch plate 21 under its own weight, to automatically latch the supporting member in the vertical stowed position. This automatic latching action is further enhanced by provided the locking member 5 with a curved rear edge (see Figure 5).
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 features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

A scaffold arrangement comprising a scaffold component and a support unit for releasably supporting the scaffold component in an operative position on a scaffold assembly or building, the support unit comprising a mounting portion for fixedly mounting the support unit to said scaffold assembly, a supporting member for seating a first part of the scaffold component, and a releasable locking member moveable to a locking position for locking the scaffold component to the support unit, the arrangement being such that when the scaffold component is seated on the supporting member in said operative position, and the locking member is in said locking position, the locking member is spaced immediately below a second part of the scaffold component and acts as a back-up supporting member for arresting uncontrolled downward movement of the scaffold component relative to the support unit.
A scaffold arrangement according to claim 1, wherein the locking member is a slidable locking member mounted for sliding movement between a retracted position and said locking position.
A scaffold arrangement according to claim 1 or 2, wherein the arrangement is provided with a locking element for locking the locking member to another part of the support unit, to prevent sliding movement of the locking member, but only if the locking member is correctly located in the locking position.
A scaffold arrangement according to claim 3, wherein the locking element is in the form of a rigid locking pin, the arrangement being configured to allow insertion of the rigid locking pin through both the locking member and another part of the support unit to prevent relative sliding movement therebetween, but only when the locking member is correctly located in the locking position.
A scaffold arrangement according to any preceding claim, wherein the locking member is slidably mounted on the supporting member and the supporting member is pivotally connected to the mounting portion such that, when the mounting portion is fixedly mounted on the scaffold assembly or building, the supporting member may be pivoted between a supporting position, wherein the supporting member projects laterally from the scaffold assembly or building, and a stowed position, wherein the supporting member is contained within the footprint of the scaffold assembly or building.
A scaffold arrangement according to claim 5 as dependent upon claim 4, wherein the arrangement is configured to allow insertion of the locking pin through both the locking member and another part of the support unit other than the supporting member, such that the locking pin additionally locks the supporting member in its supporting position.
A scaffold arrangement according to claim 6, wherein the support unit is provided with a fixed catch member, the catch member and sliding locking member co-operating with one another to form a latch wherein, when the supporting member is in said stowed position, the locking member may be slid to said retracted position to engage the catch member and retain the supporting member in the stowed position.
A scaffold arrangement according to claim 7, wherein in said supporting position the supporting member extends upwardly such that the locking member may slide downwardly to said retracted position under its own weight, thereby automatically engaging the catch member to retain the supporting member in the stowed position.
A scaffold arrangement according to claim 8, wherein the catch member is positioned to abut against the locking member and thereby slide the locking member relative to the supporting member as the latter is pivoted from the supporting position towards the stowed position, wherein the locking member is prevented from dropping to the retracted position, and thereby interfering with the pivoting of the supporting member, until such time as the supporting member reaches the upwardly extending stowed position.
A scaffold arrangement according to claims 4 and 5, wherein the support unit comprises a pair of generally parallel mounting elements, the supporting member being pivotally mounted between the mounting elements, and parallel with the mounting elements, the mounting elements being configured to receive the locking pin therethrough such that the locking pin extends between the mounting elements for preventing the supporting member from returning to the supporting position from the stowed position.
A scaffold arrangement according to any of claims 7 to 9, wherein the support unit comprises a pair of generally parallel beams, the supporting member being pivotally mounted between the beams, and parallel with the beams, and the catch member being in the form of a catch plate extending laterally between the beams.
A scaffold arrangement according to any preceding claim, wherein the first and second parts of the scaffold component are in the form of two generally parallel support bars, the support bars being arranged on the scaffold component so as to be generally horizontal when the scaffold component is in said operative position, the supporting member comprising an upturned hook portion for receiving and seating a lower one of the support bars with the scaffold component in the operative position, the locking member being in the form of an elongate, slidable locking arm mounted to the supporting member for sliding movement to said locking position, in which the locking arm projects between the lower support bar and the other, upper support bar and is spaced immediately below the upper support bar.
A support unit for use in the scaffold arrangement of claim 1, the support unit comprising a mounting portion for fixedly mounting the support unit to said scaffold assembly, a supporting member for seating the first part of the scaffold component with the scaffold component in an operative position, and a slidable locking member moveable from a retracted position to a locking position for locking the scaffold component to the support unit, the locking member having sufficient load-bearing capability for arresting uncontrolled downward movement of the scaffold component from its operative position when the locking member is in the locking position.
A support unit according to claim 13, wherein the unit is provided with a locking element for locking the locking member to another part of the support unit, to prevent sliding movement of the locking member, but only if the locking member is correctly located in the locking position.
A support unit according to claim 13, wherein the locking element is in the form of a rigid locking pin, the unit being configured to allow insertion of the rigid locking pin through both the locking member and another part of the support unit to prevent relative sliding movement therebetween, but only when the locking member is correctly located in the locking position.
A support unit according to any of claims 13 to 15, wherein the locking member is slidably mounted on the supporting member and the supporting member is pivotally connected to the mounting portion such that, when the mounting portion is fixedly mounted on the scaffold assembly, the supporting member may be pivoted between a supporting position, wherein the supporting member projects laterally from the scaffold assembly, and a stowed position, wherein the supporting member is contained within the footprint of the scaffold assembly.
A support unit according to claim 16, wherein the support unit is provided with a fixed catch member, the catch member and sliding locking member co-operating with one another to form a latch wherein, when the supporting member is in said stowed position, the locking member may be slid to said retracted position to engage the catch member and retain the supporting member in the stowed position.
A support unit according to claim 17, wherein in said supporting position the supporting member extends upwardly such that the locking member may slide downwardly to said retracted position under its own weight, thereby automatically engaging the catch member to retain the supporting member in the stowed position.
A support unit according to claim 18, wherein the catch member is positioned to abut against the locking member and thereby slide the locking member relative to the supporting member as the latter is pivoted from the supporting position towards the stowed position, wherein the locking member is prevented from dropping to the retracted position, and thereby interfering with the pivoting of the supporting member, until such time as the supporting member reaches the upwardly extending stowed position.
A support unit according to claims 15 and 16, wherein the support unit comprises a pair of generally parallel beams, the supporting member being pivotally mounted between the beams, and parallel with the beams, each beam having an associated key-hole, the key-holes being aligned opposite one another for receiving the locking pin therethrough.
A support unit according to any of claims 17 to 19, wherein the support unit comprises a pair of generally parallel beams, the supporting member being pivotally mounted between the beams, and parallel with the beams, and the catch member being in the form of a catch plate extending laterally between the beams.
A support unit according to any of claims 12 to 20, being for use in the scaffold arrangement of claim 11, wherein the supporting member comprises an upturned hook portion for receiving and seating a lower one of the support bars with the scaffold component in the operative position, the locking member being in the form of an elongate, slidable locking arm mounted to the supporting member for sliding movement to said locking position.