CA1263428A - Drop scaffolding structure and method of erecting same - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A drop scaffolding structure and a method of erecting the same are provided. The scaffolding structure comprises a pair of vertically extending drop tubes each of which has a top coupling secured by a first securing means to an upper part of the drop tube against axial movement relative to the drop tube and a bottom coupling secured by a second securing means to a lower part of the drop tube against axial movement relative to the drop tube. Each top coupling in the structure has a cradle with an opening directed generally downwardly and each bottom coupling is provided with a cradle having an opening extending generally upwardly. An upper scaffold tube extends horizontally between the two drop tubes and is releasably secured in the cradles of the two top couplings to suspend the drop tubes from the upper tube. A lower scaffold tube is also provided which extends horizontally between the two drop tubes and is releasably secured in the cradles of the two bottom couplings that are to be supported.

Description

This invention relates to a method of erecting drop scaffolding to a drop scaffolding structure and to a scaffold coupling usable in the erection of drop scaffolding.
There are many environments where a scaffold needs to be erected below a surface and where there is no practical method of supporting that scaffold from below. It is therefore necessary to support the scaffold from above and this is effected by securing drop tubes to the underside of the surface, by climbing down the drop tubes and using conventional bolted scaffold clamps to secure hori~ontal ledger and transom tubes to the end of the drop tubes. The dangers of this practice are evident, particularly in hostile environments such as offshore oil rigs, and it is furthermore a time-consuming process.
It is therefore an object of the present invention to obviate or mitigate the above disadvantages.
According to the present invention there is provided a method of erecting a drop scaffolding structure comprising the steps of:
taking a first drop tube and a second drop tube, each of said drop tubes having a respective top coupling secured to an upper portion thereof via first securing means to prevent axial movement therebetween, each of said drop tubes having a respective bottom coupling secured to a lower portion thereof via second securing means to prevent axial movement therebetween, each of said top couplings being provided with a cradle, the cradle of each of said top couplings being downwardly inclined when said first and second drop tubes are in a substantially vertical orientation, each of said bottom couplings being provided with a cradle, the cradle of each of said bottom couplings being upwardly inclined when said drop tubes are in said substantially vertical orientation;
extending an upper scaffolding member between said first and second drop tubes;
engaging the cradle of each of said top couplings with said upper scaffolding member when said first and second drop tubes are positioned to form an acute angle with a substantially vertical axis;
pivoting said top couplings about said upper scaffolding .:,. . .

- 3 - 12634~
ember to a position wherein said first and second drop tubes extend substantially parallel to said vertical axis;
securing each of said top couplings to said upper scaffolding member to prevent pivoting of said drop tubes;
extending a lower scaffolding member between said first and second drop tubes;
engaging the cradle of each of said bottom couplings with said lower scaffolding member; and securing each of said bottom couplings to said lower scaffolding member thereby forming said drop scaffolding structure.
Other methods of erecting a drop scaffolding structure are also provided.
In another aspect of the present invention there is provided a drop scaffolding structure comprising:
an upper substantially horizontal scaffolding member and a lower substantially horizontal scaffolding member;
a first substantially vertical drop tube and a second substantially vertical drop tube, each of said first and second drop tubes having a respective top coupling secured to an upper portion thereof via first securing means to prevent axial movement therebetween and a respective bottom coupling secured to a lower portion thereof via second securing means to prevent axial movement therebetween, each of said top couplings being provided with a cradle, the cradle of each of said top couplings being downwardly inclined when said drop tubes are in a substantially vertical orientation and being for engaging either ends of said upper scaffolding member, each of said bottom couplings being provided with a cradle, the cradle of each of said bottom couplings being upwardly inclined when said drop tubes are in said substantially vertical orientation and being for engaging either ends of said lower scaffolding member, each of said cradles including locking means for releasably securing said respective top and bottom couplings to said respective upper and lower scaffolding members, said first and second drop tubes and said lower scaffolding member defining a trapeze-like structure, said trapeze-like structure being pivotable about said upper scaffolding member when said locking means associated with the cradle of each of said top couplings is released, said top . . l - . . ,;., : -, .- .

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:IL2634:~8 - 3a -ouplings being secured to said upper scaffolding member via said locking means when said drop tubes are substantially parallel to said vertical axis to inhibit pivoting of said trapeze-like structure relative to said upper scaffolding member thereby forming said drop scaffolding structure.
An embodiment of the present invention will now be described by way of example only, with reference to the ~2634:213 ,~
accompanying drawings in which:
Figure 1 is a plan view of a coupling according to the invention;
Figure 2 is a cross-section on the line II-II of Figure l;
Figura 3 is an elevation in the direction of the arrow III
of Figure 2;
Figure 4 is an elevation in the direction of the arrow IV of Figure 2; and Figures 5 and 6 are respectively end and side schematic elevations of a drop scaffolding according to the invention.
Referring to Figures 1 to 4, a coupling for use in a scaffolding structure is shown. The coupling comprises a body that includes first and second end walls 1, 2, a front wall 3, a rear wall 4 and side walls 5 and 6. The first end wall 1 has an opening 7 therein, the opening having, in upper plan view, a rearward part-circular section 8 and a forward section 9 that flares outwardly in the forward direction. The second end wall 2 terminates rearwardly ln a part-circular section 10, the centres of the circles from which the sections 8 and 10 are drawn lying on a common axis A-A passing through the hollow section within the body and which is considered as the longitudinal axis of the coupling. Each of the sections 8 and 10 subtends an angle of approximately 180 to this axis. A further body part pro~ects forwardly towards the axis from the rear wall 4 and presents a part-circular section 11 that is longitudinally aligned with and spaced from the section 8. The three part-circular sections 8, 10 and 11 each subtend an angle not exceeding 180 to the axis A-A and have a diameter that matches the standard outside diameter of a scaffold tube. The secttions thus act as guides for locating a drop tube, shown in phantom outline as 12 in position in the coupling with the axis of the drop tube ~f~l ,~ ~

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substantially coincident with the longitudinal axis A-A of the coupling. In this position the drop tube lies between the side walls 5 and 6 ~ith clearance between the tube and the respective side walls fur reasons which will become apparent. The tube also lies adjacent to bui spaced from the rear wall 4 and in contact with a lower part 3a of the front wall 3, the - .upper part 3b of which i5 inclined aw2y from the axis A-A towards the end wall 1.
The two side walls 5 and 6 are each formed with a hook section, 13f 14 respectively which projects fro~
the front wall of the body away from the longitudinal axis A-A. The hook sections are joined together by an extension 3c of the front wall 3, extending firstly at àpproximately 90 away from the axis A-A and then inclined at an angle to suit the hook sections. The extension acts as a spacer and stiffener for the hook sectionsO The two hooks together form a hook-li~e cradle having a semi-circular base 14b and parallel retaining walls 14 , 14d extending from the base to an opening that extends diagonally outwardly of the body and.towards.the first end thexeof. The retaining walls each make an acute angle CC with the longitudinal axis A-A in the quadrant that includes the first end wall 1 of the body, the angle CC in the embodiment shown being 45 and in any case being preferably not more than 60. The cradle has an end-to-end axis B-B
that is perpendicular to the longitudinal axis A-A.
The cradle opening has a width X which is sli~htly greater than the outside diameter of a scaffold tube .. and which leads into the semi-circular base of the cradle which has a diameter determined by the part-circular sections of the two hooks and which is also slightly greater than the external diameter of a scaffold tube. Accordingly, a scaffold tube as shown in phantom outline at 15 can be received in the cradle to extend -` ~26342~

,; _ perpendicula~ to the drop tube 12 and with its axis substantially coincident with the axis B-B of the - cradle~
Once in position within the craale a -tube such as : 15 may be Iocked to prevent.its release from the -cra~le by a locking element shown generally as 16 slidably mounted on the bod~.for movement in the .~ direction that is mutually perpendicular to the axes A-A and B-B~ The locking element has side plates 18 . 10 and 19 which pass through respective slots ~0 and.21 in the rear wall 4 of the body and.through`respective slots 22 and 23 in the front wall 3 of the body. Within the body the side plates extend to opposite sides of the p.a~h of the drop tube 12 so that each side plat~
lies.in a respective clearance between the drop tube and the adjacent side walls 5 o.r 6 o the body. The lower leading edges of the side plates 18 and 19 are . ~~
tapered as at 24 and the plates are joined by a crvss-member 25 lying outside the body l. The rear ends of the side plates 18 and 19 are bent.through 90 to for~
sections 26, 27 lying.outside the rear wall o the .body and terminating closely adjacent one to the other or ioined one to.the other. The sections 26 and 27 form a striker plate which may he.struck to mo~e the locking element from the rearward position shown in .solid lines in Figure 2 wherein it lies clear of ~e cradle opening.to the forward position shown in phantom outline in Figure 2 wherein the leading sections of the side ~alls. 18 and 19 restrict the cradle opening to lock the scaffold tube 15 in position in the cradle. The tapered formation of th.e.lower leading edges of the side plates of the locking element facilitates this movement of the element. The taper lock is obtained by the upper edges of theside plates . 18 and 19 bearing against the lower face of a further extension 3d of the front wall, and the tapered .

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`` ~,Z6342~3 _ ~ _ formation of the lower leading edges o~ those plates bearing directly on the tube lS.
As well as locking the tube 15 to the coupling it is of ~urse necessar~ to lock the coupling to the drop tube 12~ In the embodiment ~hown in the drawings the position of the coupling on the drop tube is adjustable, and for this purpose the drop tube is formed with twv opposed sets of l~ngitudinally spaced holes, the holes forming diametricall~ opposite pairs such as 30, 31 and 32, 33. Alternatively, the holes in one set ma~ be staggered longitudinally.relative to those in ~he other set. A first pin 34 o~ diameter less than the diam~ter of the holes in the drop tube extends through the thlck-ness of, and is welded to, the rear wall 4 o~ the bodyO
A second pin 35 of substantially the s~e diameter as pin 34 extends over the exten.sion 3c of the front wall, through the section 3a of the front wall 3 and is welded to the extension and to the section. The pins 3~ and 3$ are displaced longitudinall~ one ~rom the other b~
a distance e~ual to the centre to centre distance between adjacent pairs of holes in the drop tube, and have .their longitudinal.axes l.~ing in a common plane with the.axis A-A. The pins extend rom opposite directions towards the axis A-A and they are therefore capable of engaging holes on opposite siaes of the drop tube 12, e.g. holes 30 and 33 as shown in Figure 2.
To effect such engagement the coupling is itted onto the drop tube with the longitudinal axis of the drop ; tube making an angle with the longitudinal axis A-A
of the coupling, for example with the drop tube at an angle as indicated by the phantom outline 12a in .
Figure 2, which may match the angle of the part 3b of the front wall 3. The drop tube and the coupling are then relatively t.ilted so that the pins 34 and 35 engage in respecti~e holes in the drop tube, the angulax entry of the drop tube into the coupling and the pivotal movement being allowed :'' ' ` "

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by the elongated space in the first end wall 1 of the coupling and the fact that the rear wall 4 of the coupling is cut away at the level of the part defining the section 11 so leaving free space between the downward extensions of the side walls 5, 6 from that part.
In order firmly to secure the coupling to the drop tube, a wedge plate 36 is provided which rests partially on the section 3_ of the front wall 3 and which extends through a slot 3~ in the side wall 6. The wedge plate 36 has a tapered edge 49 facing towards the axis A-A. The wedge plate may be withdrawn in the direction of the arrow Y from the locking position shown in Figure 1 and in that position it does not restrict movement of the drop tube within the body. However, when the drop tube has been inserted and the pins 34, 35 have been properly engaged with the holes in that tube the wedge plate may be moved to the position shown in Figure 1 wherein it contacts the drop tube on the side diametrically opposite from the region of engagement of the pin 34. Thus, pivoting of the drop tube about the fulcrum formed by the region 40 of the front wall is positively prevented and the coupling is locked firmly to the tube. It should in any case be noted that when the coupling is in use under a load, the natural tendency is for the coupling to pivot in a sense that will tend to force the pins 34 and 35 into, rather than out of the holes 30 and 33.
The simplicity with which the coupling shown in the drawings can be used will now be appreciated. Both the drop tube ~ 2~3~21~

- ~a -and the second tube may be fitted readily into their respective locations within the coupling and are then locked in place by a simple sliding action of the respective wedge. The need for bolts in this coupling is eliminated. The coupling has inbuilt fail-safe qualities in that even if both locking wedges " 12~3428 should fail under fully loaded conditions the coupling will not slide off the drop tube nor will the coupling and the cross tube become disengaged~ It will be appreciated that thecoupLing may be fitted to the drop tube eîther with the first end wall uppermost as shown in the drawings~ Qr with the second end wall uppermost. In the former posîtlon the coupling is used to support a transom tube from the drop tube~ desirably at the lower end of the drop tube. In the latter position an inverted coupling at the upper end of the drop tube may be used to support the drop ~ube from a horizontal scaffold tube near the upper end thereof.
This arrangement makes possible the erection of drop scaffolding in a much safer way than has heretoore been possible, as will become apparent from the following description. Before giving that description, however, it should be stated that in a modified form of the coupling it may be designed so that it can be welded at each end wall thereof to a tube that is destined to be a drop tube. The coupling shown in the drawings could of course, after the coupling has been fitted to the tube so that the pins 34 and 35 engage holes in the tube, be secured by welding between the sections 8, 10 and 11 and the tube. However, with a welded connection between the coupling and the tube the pins are not necessary, neither is it necessary to have the elongated opening 7 in the first end wall of the coupling or the cut-away region below the part defining the section 11 and extending inwardly rom the rear wall.
The coupling may thus be formed with a continuous rear wall and with first and second end walls that are continuous except for aligned circular openings having centres lying on the axis A-A of the couplings and having diameters such that they will be a close fit , e ~263428 ~`
~1 around a scaffold tube. Such a coupling may thus be slid onto a tube with the tube passing through ~he aligned openings in the end walls, and a connection may then be effected by ~lding be~ween ~he tube and s ~he end walls around the openin~ in those walls~
Where adjustability is not re~uired drop tubes may be pre-fitted with t~o such couplillys, one adjacent to each end of the drop tube, the couplings being - inverted one with respect to the other and ha~ing their cradles each opening generally towards the centre of the tuber Figurès 5 and 6 illustrate schematically one way in which the couplings described may be used in erecting a drop scaffold below two beams 50 and 51 t the beams being spanned by a serles of scaffold tubes 52a, 52b, 52c etc~ secured e~ual distances apart to the upper side of the beams. Alternatively these cross tubes could be tubes of measured length secured-to the upper faces of the lower flanyes of the beams and extending between the walls of those beams. A
first trapeze-like structure 53a is erected on a platform above the beam. The structure 53a comprises two drop tubes 54, 55 each having a coupling 56, 57 respectively welded or othexwise secured adjacent to its upper end and presenting a downwardly opening cradle. Two further couplings 58, 59 inverted with resp$ct to the couplings 56, 57 are welded or otherwise secured to the drop tubes adjacent to their lo~er ends. A cross tube 60 is inserted into the upwardly opening cradles of couplings 58 and 59 and is secured in position in those cradles by appropriate movement of the locking element 16 of each coupling. This structure is lowered from above the beams until the couplings 56 and 57 engage over the first cross tube 52a. When such engagement has been effected the locking elements 16 of those couplings are moved to the locking position .
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~2~342~3 ll so that a secure connection is established between the cross tube 52a and the drop tubes 54, 55. Similar trapeze-like structures 53b, 53c e~c. may then be located.
If access can readily be gained from the top of the beams then each such structure may simply be dropped from above the beams and secured as alread~ described. If, however, access from the top of the beams is not available then workmen may readily descend the drop tubes 54, 55 of the first structure 53a to find a secure foot-hold OIl the 10 cxoss tube 60. From that posit:ion they may proJec~
forward either an already erected second trapeze-like structure, or individual drop tu~es followed by ~he cross tube, and may hook the two couplings at the upper ends of .
the drop tubes of that structure over the appropriate cross tube, for example as indicated in connection with cross tube 52d~ Having effected this hook engagement the struc-ture may then merely be allowed to swing into position about those couplinys after which it will stabilise to a position where the drop tubes hang vertically. As soon as two such trapeze-like structures are in position it will be apparent that boards can be positioned to span the cross tubes of the two adjacent structures thus giving an extremely safe working platform from which further struc-tures may be ad~anced to extend the scaffold as required.
The trapeze-like structures will, in the final erected scaffold, be linked by ledgers secured above and to the cross tubes by conventional fittings and guard rails sec-ured to the drop tubes by conventional fittings. Transom tubes are secured above and to the ledgers at regulation spacings and boards are laid on the transoms. This link-ing proceeds bay by bay in conjunction with the formation and fixing of each trapeze-like structure. Alternatively, lightweight stagings may be used rather than scaffoldboards, so removing the necessity for ledgers and transoms. In this case linking of the trapeze-like structures will be effected through the handrailing of the stagings.

i34X~3 '1~' Figures 5 and 6 show a different way in which the working platfoxm may be const~ucted by using two further couplings 61 and 62, also welded or otherwise secuxed to the drop tubes immediately adjacen~ the couplings 58, 5~ but rotated xelativel~ to those couplin~s about the axis of the drop tubes through angles of 90 .
The aligned couplings 61 or 62 of a plurali~y cf trape~e-like stxuctures may be used to support horizontally extending ledger tubes 63, G4. Transom tubes such as 65 may be secured to the ledger tubes 63 and 64 by conventional scaffold fi~ings and they may be used as supports for planks or decking 66. The advantage of this structure which spaces the transom tubes 65 significantly above the cross tubes 50 is that it enables an auxiliary platform 67 to be posi~ioned between the cross tubes and transom tubes as shown in ~igure 6, and to be cantilevered out beyond the end of the last secure trapeze-like structure, forexample beyond the structure 53c as shown in Figure 6. This extension of the safe working surface further facilitates the erection and securing of the next trapeze-like structure~
The advantage of having immediate safe working platforms will readily be appreciated. The simplicity of erection will also be evident,: particularly the ~ -advantage of being able to effect locking to the coupling by a simple sliding movement of an appropriate locking element the movement being effected, for example,by striking the element with a hammer. This contrasts well with the need in conventional systems to ensure that clamping bolts are properly tightened.
Similarly, unlocking can be effected by a simple striking action, rather than removal of bolts. Systems using adjustable coupling members may be utilised to provide scaffolds having different headrooms. Drop tubes having coupling members welded thereto at fixed . .

' ;3428 \~
- ~4 -spacîn~s may be used to construct scaffolds with fixed headroom. It will of cour5e be understood that the two arrangements may be combined as re~ui~edJ

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Claims (6)

We Claim:

1. A method of erecting a drop scaffolding structure comprising the steps of:
taking a first drop tube and a second drop tube, each of said drop tubes having a respective top coupling secured to an upper portion thereof via first securing means to prevent axial movement therebetween, each of said drop tubes having a respective bottom coupling secured to a lower portion thereof via second securing means to prevent axial movement therebetween, each of said top couplings being provided with a cradle, the cradle of each of said top couplings being downwardly inclined when said first and second drop tubes are in a substantially vertical orientation, each of said bottom couplings being provided with a cradle, the cradle of each of said bottom couplings being upwardly inclined when said drop tubes are in said substantially vertical orientation;
extending an upper scaffolding member between said first and second drop tubes;
engaging the cradle of each of said top couplings with said upper scaffolding member when said first and second drop tubes are positioned to form an acute angle with a substantially vertical axis;
pivoting said top couplings about said upper scaffolding member to a position wherein said first and second drop tubes extend substantially parallel to said vertical axis;
securing each of said top couplings to said upper scaffolding member to prevent pivoting of said drop tubes;
extending a lower scaffolding member between said first and second drop tubes;
engaging the cradle of each of said bottom couplings with said lower scaffolding member; and securing each of said bottom couplings to said lower scaffolding member thereby forming said drop scaffolding structure.

2. A method of erecting a drop scaffolding structure comprising the steps of:
taking a first drop tube and a second drop tube, each of said drop tubes having a respective top coupling secured to an upper portion thereof via first securing means to prevent axial movement therebetween, each of said drop tube having a respective bottom coupling secured to a lower portion thereof via second securing means to prevent axial movement therebetween, each of said top couplings being provided with a cradle, the cradle of each of said top couplings being downwardly inclined when said first and second drop tubes are in a substantially vertical orientation, each of said bottom couplings being provided with a cradle, the cradle of each of said bottom couplings being upwardly inclined when said drop tubes are in said substantially vertical orientation;
extending an upper scaffolding member between said first and second drop tubes;
engaging the cradle of each of said top couplings with said upper scaffolding member when said first and second drop tubes are positioned to form an acute angle with a substantially vertical axis;
extending a lower scaffolding member between said first and second drop tubes;
engaging the cradle of each of said bottom couplings with said lower scaffolding member to form a trapeze-like structure defined by said first and second drop tubes and said lower scaffolding member;
pivoting said trapeze-like structure about said upper scaffolding member to a position wherein said first and second drop tubes extend substantially parallel to said vertical axis; and securing each of said top couplings to said upper scaffolding member to prevent pivoting of said trapeze-like structure thereby forming said drop scaffolding structure.

3. A method of erecting a drop scaffolding structure comprising the steps of:
taking a first drop tube and a second drop tube, each of said drop tubes having a respective top coupling secured to an upper portion thereof via first securing means to prevent axial movement therebetween, each of said drop tubes having a respective bottom coupling secured to a lower portion thereof via second securing means to prevent axial movement therebetween, each of said top couplings being provided with a cradle, the cradle of each of said top couplings being downwardly inclined when said drop tubes are in a substantially vertical orientation, each of said bottom couplings being provided with a cradle, the cradle of each of said bottom couplings being upwardly inclined when said drop tubes are in said substantially vertical orientation;
extending a lower scaffolding member between said first and second drop tubes;
engaging the cradle of each of said bottom couplings with said lower scaffolding member to form a trapeze-like structure;
coupling said trapeze-like structure to a substantially horizontal upper scaffolding member via the cradles of said top couplings when said first and second drop tubes are positioned to form an acute angle with a substantially vertical axis;
pivoting said trapeze-like structure about said upper scaffolding member to a position wherein said first and second drop tubes extend substantially parallel to said vertical axis; and securing each of said top couplings to said upper scaffolding member to inhibit pivoting of said trapeze-like structure thereby forming said drop scaffolding structure.

4. A drop scaffolding structure comprising:
an upper substantially horizontal scaffolding member and a lower substantially horizontal scaffolding member;
a first substantially vertical drop tube and a second substantially vertical drop tube, each of said first and second drop tubes having a respective top coupling secured to an upper portion thereof via first securing means to prevent axial movement therebetween and a respective bottom coupling secured to a lower portion thereof via second securing means to prevent axial movement therebetween, each of said top couplings being provided with a cradle, the cradle of each of said top couplings being downwardly inclined when said drop tubes are in a substantially vertical orientation and being for engaging either ends of said upper scaffolding member, each of said bottom couplings being provided with a cradle, the cradle of each of said bottom couplings being upwardly inclined when said drop tubes are in said substantially vertical orientation and being for engaging either ends of said lower scaffolding member, each of said cradles including locking means for releasably securing said respective top and bottom couplings to said respective upper and lower scaffolding members, said first and second drop tubes and said lower scaffolding member defining a trapeze-like structure, said trapeze-like structure being pivotable about said upper scaffolding member when said locking means associated with the cradle of each of said top couplings is released, said top couplings being secured to said upper scaffolding member via said locking means when said drop tubes are substantially parallel to a vertical axis to inhibit pivoting of said trapeze-like structure relative to said upper scaffolding member thereby forming said drop scaffolding structure.

5. A drop scaffolding structure comprising:
a first drop scaffolding tube and a second drop scaffolding tube, each of said drop tubes having a respective top coupling secured to an upper portion thereof via first securing means to prevent axial movement therebetween, each of said drop tubes having a respective bottom coupling secured to a lower portion thereof via second securing means to prevent axial movement therebetween, each of said top couplings being provided with a cradle, the cradle of each of said top couplings being downwardly inclined when said drop tubes are in a substantially vertical orientation, each of said bottom couplings being provided with a cradle, the cradle of each of said bottom couplings being upwardly inclined when said drop tubes are in said substantially vertical orientation, each of said cradles being provided with locking means;
a lower scaffolding member extending between said first and second drop tubes and being releasably secured in the cradle of each of said bottom couplings via said locking means to form a trapeze-like structure defined by said drop tubes and said lower scaffolding member, said trapeze-like structure being releasably securable to a substantially horizontal upper scaffolding member by engaging the cradles of said top couplings to said upper scaffolding member when said trapeze-like structure is positioned to form an acute angle with a vertical axis, pivoting the trapeze-like structure about the upper scaffolding member to a position wherein said first and second drop tubes extend substantially parallel to said vertical axis and securing said top couplings to said upper scaffolding member via the locking means of said top couplings to prevent movement of said trapeze-like structure relative to said upper scaffolding member thereby forming said drop scaffolding structure.

6. A drop scaffolding structure as defined in Claims 4 or 5 wherein the first securing means of at least one of said top couplings is releasably coupled to said respective first and second drop tubes to permit axial movement between said drop tube and said top coupling thereby allowing the position of said coupling along said drop tube to be adjusted.