"A METHOD AND APARATUS FOR ERECTING A MOBILE SCAFFOLD TOWER"

Introduction

The present invention is directed to a method of erecting a scaffold tower and to the scaffold tower itself comprising a platform section and a plurality of stackable prop sections.

In particular the invention is directed to mobile scaffold towers.

Mobile scaffold towers are used to gain temporary access to work areas located at height from ground-level. The towers are used when a ladder would be unsuitable and when a fully fixed scaffold system would be too laborious to construct given the temporary nature of the required access. Typically, the mobile scaffold towers would be for gaining access to work areas at heights of approximately one meter to ten metres from ground-level. It will be understood that references to the terms "ground" and "ground-level" throughout the following specification should be interpreted as referring to the support surface upon which the scaffold tower is erected, which could be any floor level within a multi-storey building.

Various different types of mobile scaffolding systems exist. One of the most commonly used mobile scaffolding systems is built using tubular aluminium bars and flooring sections.

The aluminium bars are coupled together to form a scaffold tower framework section, atop which the flooring sections are fixed. The scaffold tower framework comprises a plurality of vertically arranged tubular bars known as standards or uprights, and a plurality of horizontally arranged shorter cross-member bars known as ledgers and transoms, which are all connected together using couplers to form the framework section in a substantially hexahedral like shape. In some systems, bracing bars are diagonally arranged between adjacent standards to provide the framework section with increased rigidity and stability. Base jacks or wheels may be arranged at the bottom of the scaffold tower. The wheels allow the mobile scaffold tower to be re-positioned as work progresses from one area to another. However, the scaffold tower cannot always be ideally positioned as the mobile scaffold tower is usually constructed in a substantially hexahedral-like shape, and

this hexahedral-like shape can make it awkward to position the mobile scaffold tower in some service areas due to vertical pipes mounted against walls and vents that protrude outwardly from walls. The transoms, standards and ledgers of the framework of the scaffold tower abuts against the pipes, vents and the like. Therefore, due to the hexahedral-like shape, in some situations, the mobile scaffold tower cannot be positioned close enough to the wall to allow the worker to safely carry out their work. Workers tend to then lean out over the side of the scaffold tower to attempt to reach the wall or work area. This is unsafe.

Currently, the only solution to this is to remove some of the transom, ledger or diagonally arranged bracing bars which are causing the obstruction by abutting against the pipes or vents. This will obviously weaken the structural integrity of the tower, and decrease the safety for workers.

The standards, ledgers and transoms used in constructing the mobile scaffold tower come in predetermined lengths: typically, most standards are between two and four metres in length, and, most ledgers and transoms are between one and three metres in length. A set of standards, ledgers and transoms are used to create prop sections for the mobile scaffold tower which are stacked atop one another to erect the mobile scaffold tower to a desired height. Throughout the following specification, the terms "prop" and "prop section" shall be understood to mean a section of scaffold that may be stacked on top of other prop sections to form the framework of the mobile scaffold tower.

A platform comprising a flooring section is normally constructed atop the tower section. The flooring sections usually comprise a plurality of wooden planks, known as battens, that are placed adjacent and in parallel with one another to form a continuous planar surface. The battens are fixed in place using specifically formed coupling members that hold the battens firmly against the ledgers and transoms so as to provide the planar surface for workers to stand or kneel upon. Alternatively, bespoke flooring elements constructed of heavy-duty plastics or metals may also be used instead of the battens. Kick boards may also be arranged around the edge of the platform.

In some mobile scaffold towers, the platform also comprises a handrail around the edge of the platform to prevent workers from falling off the scaffold tower. These

handrails are usually formed using the ledgers. For safety reasons, workers are required to wear a harness which is attached to a suitable harness anchor point using a lanyard. In everyday situations, workers attach the lanyard to the handrails or other bars of the scaffold tower.

It can be problematic to use the standards, ledgers and transoms as anchor points because if there are a number of workers on the platform, as the worker moves about on the platform and passes by the other workers, the worker will need to detach and reattach their lanyard to different anchor points on the handrail. Otherwise, the lanyards of the different workers would become tangled with each other. A second problem with attaching the lanyard to the handrails of the scaffold tower is that a worker who falls over the edge of the scaffold tower could tip the scaffold tower over on top of themselves.

During construction of the mobile towers, workers build the scaffold tower progressively upwards by erecting a first prop section using the standards, ledgers and transoms whilst standing at ground level. Then, by standing on the first constructed prop section, a second prop section is coupled to the first prop section. In this manner, several prop sections can be coupled to one another to form multiple stacked prop sections. Thus, the height of the mobile scaffold tower can be progressively extended upward.

It will be appreciated that during the majority of the construction process, workers must stand on ledgers and transoms of existing constructed prop sections in order to construct the next prop section. This is dangerous as at least one worker is required to climb on a partially erected scaffold tower as the scaffold tower is erected beyond the first level of ledgers and transoms. Clearly this is unsatisfactory and a safer erection method is sought.

Furthermore, the standard, transom and ledger bars are passed up to the worker who couples the bars to the existing partially constructed tower. This is also dangerous as the worker needs to handle, position and secure these bars at height.

It is a goal of the present invention to overcome at least some of the aforementioned problems.

Statements of Invention

The present invention is directed to a method of erecting a scaffold tower having a plurality of stackable tower sections, characterised in that the method comprises the steps of hoisting a partially erected scaffold tower, comprising one or more tower sections, up to a predetermined height above ground-level; arranging a further tower section beneath the hoisted partially erected scaffold tower; and, affixing the further tower section to the hoisted partially erected scaffold tower to form the scaffold tower.

The advantage of using this method of erecting a scaffold tower is that it enables workers to construct the scaffold tower whilst remaining at ground level. No worker is required to climb onto a partially erected scaffold tower to erect any tower sections.

A lifting mechanism is used to raise the partially erected scaffold tower to a predetermined height above ground level. Then a further tower section can be placed beneath the hoisted partially erected scaffold tower, or could be constructed beneath the hoisted partially erected scaffold tower, and the further tower section is manually lifted up and connected to the bottom of the partially erected scaffold tower. The scaffold tower is then lowered back down onto the ground. During the entire process the workers erecting scaffold tower can remain on the ground and this is far safer than having to require a worker to climb on a partially constructed scaffold tower to build the next tower section in the scaffold tower.

In a further embodiment, the method further comprises repeating the above-mentioned steps as required to increase the height of the scaffold tower to a desired height.

In a further embodiment, the method comprises the steps of lifting the further tower section off ground-level and affixing the further tower section to the hoisted partially erected scaffold tower to form the scaffold tower; and, then lowering the scaffold tower onto the ground-level.

In a further embodiment, the method comprises the step of lowering the hoisted partially erected scaffold tower down onto the further tower section and affixing the further tower section to the hoisted partially erected scaffold tower to form the scaffold tower.

In a further embodiment, the scaffold tower comprises a plurality of stackable prop sections and a platform section, and the method further comprises the step of affixing the platform section to one of the plurality of prop sections to form the partially erected scaffold tower.

In a further embodiment, the method further comprises the step of constructing each of the plurality of tower sections at ground-level from a plurality of component parts.

In a further embodiment, the method further comprises the steps of engaging the partially erected scaffold tower with a lifting mechanism; and, lifting the partially erected scaffold tower into a hoisted position using the lifting mechanism.

In a further embodiment, the method further comprises the steps of engaging the partially erected scaffold tower with a leverage-based lifting mechanism; and, levering the partially erected scaffold tower into a hoisted position using the leverage-based lifting mechanism.

The present invention is further directed towards a scaffold tower of knock-down construction comprising a plurality of stackable tower sections, wherein, each stackable tower section comprises a plurality of jacking points adapted to engage with associated lifting members on a cooperating lifting mechanism to hoist one or more stacked tower sections above ground level.

The advantage of using a plurality of jacking points adapted to engage with associated lifting members on a cooperating lifting mechanism to hoist the tower sections above ground level is that it enables workers to construct the mobile scaffold tower whilst remaining at ground level. No worker is required to climb onto a partially erected scaffold tower to erect any prop sections.

A lifting mechanism is used to raise the partially erected scaffold tower to a predetermined height above ground level. Then a further tower section can be placed beneath the hoisted partially erected scaffold tower, or could be constructed beneath the hoisted partially erected scaffold tower, and the further tower section is manually lifted up and connected to the bottom of the partially erected scaffold tower. The scaffold tower is then lowered back down onto the ground. During the entire process

the workers erecting scaffold tower can remain on the ground and this is far safer than having to require a worker to climb on a partially constructed scaffold tower to build the next tower section in the scaffold tower.

In a further embodiment, the jacking points are mounted at outer points of each stackable tower section.

In a further embodiment, the lifting mechanism comprises an L-shaped lever having a scaffold support arm connected to an elongated lever arm at inner ends of the scaffold support arm and the elongated lever arm; an outer end of the scaffold support arm comprising means for engaging one or more of the plurality of jacking points on the scaffold tower; and, a wheel being mounted substantially adjacent the inner ends of the scaffold support arm and the elongated lever arm.

In a further embodiment, the scaffold support arm is cranked.

In a further embodiment, an angle of less than 90° is formed between the scaffold support arm and the elongated lever arm.

In a further embodiment, an acute angle of in the range of 80° to 89° is formed between the scaffold support arm and the elongated lever arm.

In a further embodiment, an acute angle of substantially 88° is formed between the scaffold support arm and the elongated lever arm.

In a further embodiment, the lifting mechanism further comprises one or more fasteners to allow the lifting mechanism to be attached to an erected scaffold tower so as to act as an outrigger for stability of the erected scaffold tower.

In a further embodiment, the one or more fasteners comprise a hook.

In a further embodiment, the scaffold tower comprises a platform section and one or more stackable prop sections beneath, whereby, an uppermost prop section, immediately beneath the platform section, comprises an upwardly extending central harness anchor point; and, a planar surface of the platform section comprises a central through hole to permit at least a portion of the central harness anchor point to protrude

through, into a position above the planar surface of the platform section.

The advantage of an uppermost prop section immediately beneath the platform section comprising a central harness anchor point is that the harness anchor point is connected directly to the prop section in a central location, and not to the battens of the platform section. As the harness anchor point is positioned above and substantially close to the planar work surface, a worker is free to move about the platform without having to constantly detach and reattach their lanyard to different anchor points. The lanyard is less likely to become tangled with other equipment on the work surface because the worker will usually be facing outwardly from the platform section, and therefore, the lanyard will extend out directly behind them to the central harness anchor point in a central part of the platform.

In a further embodiment, the harness anchor point is mounted on an uppermost end of a central upright mast of the uppermost prop section.

In a further embodiment, the harness anchor point is demountably attached to the uppermost end of the central upright mast of the uppermost prop section.

In a further embodiment, each stackable tower section comprises complementary inter- engaging connector means.

In a further embodiment, the connector means comprises a releasable connector having a male projection on one stackable tower section and a complementary female receiver on another stackable tower section.

In a further embodiment, the scaffold tower further comprises demountable wheels that have complementary inter-engageable wheel connector means to affix to an underside of any of the plurality of stackable tower sections.

In a further embodiment, the wheel connector means comprises a releasable connector having a male projection on the demountable wheels and a complementary female receiver on the stackable tower sections.

In a further embodiment, each stackable prop section comprises four vertical corner bars and two cross members, whereby diagonally opposed pairs of corner bars are

connected by one of the two cross members such that the two cross members crisscross each other at their respective mid-points to form an X-shaped prop section in plan view.

The advantage of the prop sections having an X-shaped framework in plan view is that the scaffold tower will comprise a structure which facilitates placement of the scaffold tower around protruding objects from a wall such as pipes and/or vents. This will allow workers to safely reach work areas at height on a wall which were previously unreachable due to the standard hexahedron shaped structure employed.

It is this X-shaped structure, which is used for the prop sections, that solves the problem of positioning the mobile scaffold tower in cluttered areas. The absence of any cross-member bars, such as ledgers or bracing bars, below the platform level allows the scaffold tower, and in particular the platform, to be positioned substantially flush against a wall as protruding pipes or vents are accommodated in the recesses of the X-shape, beneath the platform.

In a further embodiment, the two cross members each comprise a single horizontal cross beam.

In a further embodiment, the two cross members each comprise a pair of spaced-apart parallel horizontal cross beams.

In a further embodiment, each stackable prop section further comprises a ladder segment which aligns with associated ladder segments on other stackable prop sections when the prop sections are affixed together so that a substantially continuous ladder is formed on the scaffold tower.

The present invention is further directed towards a stackable prop section suitable for use with a scaffold tower as hereinbefore described, the prop section comprising four vertical corner bars and two cross members, whereby diagonally opposed pairs of corner bars are connected by one of the two cross members such that the two cross members criss-cross each other at their respective mid-points to form an X-shaped prop section in plan view.

The advantage of the prop sections having an X-shaped structure in plan view is that

the scaffold tower will comprise a framework which facilitates placement of the scaffold tower around protruding objects from a wall such as pipes and/or vents. This will allow workers to safely reach work areas at height on a wall which were previously unreachable due to the standard hexahedron shaped structure employed.

It is this X-shaped structure, which is used for the prop sections, that solves the problem of positioning the mobile scaffold tower in cluttered areas. The absence of any cross-member bars, such as ledgers or bracing bars, below the platform level allows the scaffold tower, and in particular the platform, to be positioned substantially flush against a wall as protruding pipes or vents are accommodated in the recesses of the X-shape, beneath the platform.

In a further embodiment, the two cross members each comprise a single horizontal cross beam.

In a further embodiment, the two cross members each comprise a pair of spaced-apart parallel horizontal cross beams.

In a further embodiment, the prop section further comprises a central harness anchor point fixedly attached to and extending upwardly from the prop section.

In a further embodiment, the prop section further comprises a harness anchor point mount to allow a demountable central harness anchor point to be demountably attached to the prop section.

In a further embodiment, the stackable prop section further comprises jacking points to engage with an associated lifting mechanism.

In a further embodiment, the jacking points are bolt receiving through holes.

The present invention is further directed towards a jacking point attachment suitable to be retrofit on a scaffold bar, wherein the attachment comprises a fastener which rigidly affixes the attachment to the scaffold bar, and the attachment further comprises a jacking point so that the jacking point may be engaged by an associated lifting mechanism to hoist the scaffold bar to an elevated position.

The advantage of using jacking point attachments as described above is that they may be retrofit onto an existing scaffold assembly kit to allow the scaffold assembly to engage with associated lifting members on a cooperating lifting mechanism to hoist the scaffold assembly so as to allow the new scaffold construction method of the present invention to be used with existing scaffold assembly kits. Thus, the jacking point attachment hoists a partially erected scaffold assembly above ground level so as to enable workers to construct the scaffold assembly whilst remaining at ground level. No worker is required to climb onto a partially erected scaffold assembly to erect the scaffold.

In a further embodiment, the fastener is a clamp.

In a further embodiment, the clamp comprises a pair of semi-tubular members hingedly attached to one another along one of their longitudinal edges and comprises interengaging complementary locking members along their other longitudinal edge.

In a further embodiment, the clamp comprises a pair of semi-tubular members, comprising interengaging complementary locking members along both of their longitudinal edges respectively.

The present invention is further directed towards a lifting mechanism suitable for use with a scaffold tower as hereinbefore described, a prop section as hereinbefore described or a jacking point attachment as hereinbefore described, wherein the lifting mechanism comprises an L-shaped lever having a scaffold support arm connected to an elongated lever arm at inner ends of the scaffold support arm and the elongated lever arm; an outer end of the scaffold support arm comprising means for engaging one or more of the plurality of jacking points; and, a pivoting member being mounted substantially adjacent the inner ends of the scaffold support arm and the elongated lever arm.

The advantage of using a lifting mechanism as described above is that the scaffold tower may be hoisted whilst partially erected to allow workers to affix further tower sections to beneath the partially erected scaffold assembly. The scaffold tower may be built whilst workers remain at ground level. No worker is required to climb onto a partially erected scaffold assembly to erect the scaffold tower.

In a further embodiment, the pivoting member is one or more wheels.

In a further embodiment, the pivoting member is a skid.

In a further embodiment, the scaffold support arm is cranked.

In a further embodiment, an angle of less than 90° is formed between the scaffold support arm and the elongated lever arm.

In a further embodiment, an acute angle in the range of 80° to 89° is formed between the scaffold support arm and the elongated lever arm.

In a further embodiment, an acute angle of substantially 88° is formed between the scaffold support arm and the elongated lever arm.

In a further embodiment, the lifting mechanism further comprises one or more fasteners to allow the lifting mechanism to be attached to an erected tower so as to act as an outrigger for stability of the scaffold tower.

The use of the lifting mechanism as an outrigger whilst the mobile scaffold tower is in use is seen as a particularly useful embodiment as the stability of the tower can be greatly increased whilst the cost of the scaffold tower assembly can be reduced because the lifting mechanism can serve two distinct purposes.

In a further embodiment, the one or more fasteners comprise a hook.

The present invention is further directed towards a scaffold tower comprising a platform section and one or more prop sections beneath, whereby a central harness anchor point is affixed to a planar surface of the platform section in a substantially central location on the planar surface of the platform section.

The advantage of providing a central harness anchor point on the planar surface is that workers will not have to constantly attach and detach themselves from the handrails on the scaffold tower.

Detailed Description of Embodiments

The invention will be more clearly understood by the following description of some embodiments thereof, given by way of example only with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of an erected mobile scaffold tower in accordance with the present invention;

Figures 2(a) to 2(j) are sequential perspective views of the mobile scaffold tower of Figure 1 during erection;

Figure 3(a) is a side view of an erected mobile scaffold tower with outriggers attached;

Figure 3(b) is a detailed perspective view of a portion of the erected mobile scaffold tower and an outrigger of Figure 3(a);

Figure 4 is a detail side view of another lifting mechanism according to a further embodiment of the present invention engaging a portion of a prop section of the scaffold tower;

Figure 5 is a detail exploded perspective view of a platform section and a prop section of another scaffold tower according to a further embodiment of the present invention;

Figure 6 is a detail exploded perspective view of a rotatable harness anchor point of the scaffold towers;

Figures 7(a) to 7(d) are perspective views of various embodiments of a retro- fitting jacking point according to the present invention; and,

Figure 8 is a perspective view of another mobile scaffold tower according to a further embodiment of the present invention.

Referring to Figure 1 , there is provided a mobile scaffold tower according to the invention indicated generally by the reference numeral 100 comprising a platform

section indicated generally by reference numeral 102 and two stackable prop sections indicated generally by reference numerals 104A and 104B. The mobile scaffold tower comprises an upper prop section 104A and a lower prop section 104B. The mobile scaffold tower 100 also comprises a plurality of wheels 106A- 106D mounted on the lowermost prop section 104B. The wheels 106A-106D are preferably caster wheels.

The platform section 102 comprises a planar work surface 108 which is fenced by handrails 110. Kickboards 1 12 are provided around the edge of the planar work surface 108.

Each stackable prop section 104A, 104B comprise four vertical corner bars 1 14A- 1 14D. The two pairs of diagonally opposed vertical corner bars 1 14A-1 14D are connected by two pairs of spaced-apart cross members 116A-1 16D. The two pairs of spaced-apart cross members 116A-1 16D comprise lower cross members 1 16A, 1 16C and upper cross members 116B, 1 16D. The diagonally opposed vertical corner bars 1 14A, 1 14C are connected to one another by a pair of spaced apart cross members 1 16C, 1 16D. The diagonally opposed vertical corner bars 1 14B, 1 14D are connected to one another by a pair of spaced apart cross members 1 16A, 1 16B. The lower cross members 116A and 1 16C criss-cross and interconnect with each other at their mid-point. The upper cross members 116B and 1 16D criss-cross and interconnect each other at their mid-point. The cross members 1 16A-1 16D are welded together in Figure 1 , however it is envisaged in further embodiments that the cross members may be detachably connected together.

The prop sections 104A, 104B are consequently X-shaped in plan view.

The four V-shaped recesses, formed as a result of the X-shaped framework, in the four sides of the prop sections 104A, 104B allow the mobile scaffold tower 100 to abut flush against a wall despite the presence of a protruding object from the wall as the protruding object can be accommodated in a recess of the prop section

104A, 104B. Vertical bracing members 1 18A-1 18D are also provided between the lower cross members 116A and 1 16C and the upper cross members 1 16B and 1 16D respectively. One of the bracing members is formed as a ladder segment

1 18C.

A central harness anchor point 120 is mounted on the upper prop section 104A. The central harness anchor point 120 is fixedly attached to the upper prop section 104A. In a preferred embodiment, the central harness anchor point 120 is welded to the upper prop section 104A. In further embodiments, every prop section 104A, 104B may be capable of mounting the central harness anchor point 120 by way of a mounting point on an uppermost part of the prop section 104A, 104B.

Referring to Figures 2(a) to 2(j), there is shown a sequence of construction stages illustrating the erection of the mobile scaffold tower 100, wherein like parts previously described have been assigned the same reference numerals.

In Figure 2(a), the upper prop section 104A comprises four vertical corner bars 1 14A-1 14D connected to the two pairs of spaced-apart cross members 116A- 1 16D to form the basic X-shaped prop section. The wheels 106A-106D are attached to the bottom of the four vertical corner bars 114A-1 14D. The central harness anchor point 120 is connected to the top of the upper prop section 104A.

The upper prop section 104A is pre-constructed in this embodiment as the vertical corner bars 114A-1 14D are welded to the two pairs of spaced-apart cross members 116A-1 16D; however, it will be appreciated that the prop section 104A may be provided as an assembly kit which can be constructed and knocked down as required for use.

Referring to Figure 2(b), platform supporting beams 122A, 122B are coupled to the upper prop section 104A.

Referring to Figures 2(c) and 2(d), the planar work surface is comprised of three battens 124A-124C. The battens 124A-124C are positioned intermediate and are coupled to the platform supporting beams 122A, 122B using a plurality of couplers 126. The three battens 124A-124C may be fabricated from wood or plastics. A leftmost batten 124A comprises a planar surface. A centre batten 124B comprises a central through hole 128 to permit a portion of the central harness anchor point 120 to protrude through it, into a position above the planar surface 108 of the platform section 102. A rightmost batten 124C comprises an access hatch 130.

In Figure 2(e), four kickboards 132A-132D are mounted about the edges of the planar work surface 108. The kick boards 132A-132D prevent objects from falling off the edge of the planar work surface 108.

Referring to Figures 2(f) and 2(g), handrails 134A-134D are coupled to the upper ends of the four vertical corner bars 1 14A-1 14D.

The partially erected scaffold tower comprising the platform section 102 and the upper prop section 104A is then manoeuvred into position using the wheels 106A- 106D.

Referring to Figure 2(h), a pair of lifting mechanisms 200A, 200B are temporarily connected to the upper prop section 104A at jacking points 222. Each lifting mechanism 200A, 200B comprises a pair of L-shaped levers which are held substantially in parallel and shaped apart by a plurality of bracing cross members 208, 214, 216. Each L-shaped lever has a scaffold support arm 202 connected to an elongated lever arm 204 at inner ends of the scaffold support arm 202 and the elongated lever arm 204. An outer end of the scaffold support arm 202 comprises means for engaging one or more of the plurality of jacking points, and, a pivoting member, in the form of a pair of skid wheels 210, is mounted substantially adjacent the inner ends of the scaffold support arm 202 and the elongated lever arm 204. A reinforcing strut 206 is fixed between the scaffold support arm 202 and the elongated lever arm 204 to give added strength to the lifting mechanisms 200A, 200B. A cross member handle 208 is fixed at a distal end of elongated lever arm 204. The bracing cross members 214, 216 fixed on the lifting mechanisms 200A, 200B give added reinforcing strength to the lifting mechanisms 200A, 200B.

As can be seen in Figure 2(i), the lifting mechanisms are leverage-based and require two operators (not shown) to simultaneously hoist the partially erected scaffold tower comprising the platform section 102 and the upper prop section 104A into an elevated position at a predetermined height above ground-level. The wheels 106A-106D have been removed from the upper prop section 104A.

With reference to Figure 2(j), the lower prop section 104B is constructed in the same manner as the upper prop section 104A. The wheels 106A-106D are affixed to the lower prop section 104B. The lower prop section 104B is then manoeuvred into

location directly beneath the partially erected scaffold tower comprising the platform section 102 and the upper prop section 104A. The lower prop section 104B is then lifted and affixed to the partially erected scaffold tower comprising the platform section 102 and the upper prop section 104A to form the erected scaffold tower 100. The lower prop section 104B may comprise a male connector (not shown) and the upper prop section may comprise cooperating complementary female connectors (not shown). The male connectors (not shown) may advantageously be interconnecting clips (not shown). The lifting mechanisms 200A, 200B are operated to lower the erected scaffold tower 100 downward onto ground level. The lifting mechanisms 200A, 200B may then be detached from the upper prop section 104A. The mobile scaffold tower 100 is erected.

Further prop sections, similar to the lower prop section 104B, may be added to increase the height of the mobile scaffold tower 100.

Workers may attach an inertia reel to the upper prop section 104A as the scaffold tower 100 is being erected. Thus, once the scaffold tower 100 has been fully erected, the inertia reel can be used by a worker as they climb the ladder 118C to the platform section 102. If the worker should slip from the ladder 118C, the fall arrest system in the inertia reel will prevent the worker from suffering any significant injuries.

Referring to Figures 3(a) and 3(b), wherein like parts previously described have been assigned the same reference numerals, there is provided an erected mobile scaffold tower 300 comprising the platform section 102 and four prop sections 104A-104D. The ladder segments 118C of each prop section 104A-104D align to form a substantially continuous ladder 118C to the platform section 102. The rightmost batten 124C is arranged so that the access hatch (not shown) is beneath the substantially continuous ladder 118C.

In this embodiment, the lifting mechanisms 200A, 200B have been left in place after the mobile scaffold tower 300 was erected so as to act as outriggers for the mobile scaffold tower 300.

In this embodiment, and referring to Figure 3(b) in particular, the lifting mechanism 200A comprises a scaffold support arm 202 that is cranked 218 intermediate its ends.

A reinforcing strut 220 is provided to give added strength to the cranked scaffold

support arm 202 of the lifting mechanism 200A. Due to the cranked nature of the scaffold support arm 202 of the lifting mechanism 200A, the weight of the mobile scaffold tower 300 acting upon the lifting mechanism 200A is directing the lifting mechanism 200A in an inward manner towards the mobile scaffold tower 300. Each jacking point 222 comprises a bifurcated tip 221 having co-linear through holes 223 which align with a through hole (not shown) on a protruding tab 136 from the scaffold tower 300, to allow a locking bolt 224 to pass through all of the through holes 223 to connect the lifting mechanism 200A to the scaffold tower 300.

A fastener 226 is used to further connect the lifting mechanism 200A to the scaffold tower 300 so that the use of the lifting mechanism 200A as an outrigger is safe. In the embodiment shown, the fastener 226 is connected to the scaffold tower 300. In further embodiments, it is envisaged that the fastener 226 may be connected to the lifting mechanism 200A, and that the protruding tab 136 on the scaffold tower 300 may be used to cooperate with the protruding tab 136 to connect the lifting mechanism 200A to the scaffold tower 300.

The description of the other lifting mechanism 200B is substantially the same of the first lifting mechanism 200A and is omitted for clarity and brevity.

It is envisaged that any number of different locking mechanisms could be used in place of the jacking point 222 and/or the fastener 226. In particular, mechanisms such as clamps, grips, hooks, bolts, buckles, buttons, catches, clasps, fastening ties, latches, locks, screws or snaps may be alternatively used. As such locking mechanisms are well known in the art.

Figures 4(a) to 4(d) illustrate various embodiments of a retrofitting jacking point 400, 410, 420, 430 which may be fixedly attached to an existing scaffold bar 423 so that existing scaffold assemblies may be used with the lifting mechanisms 200A, 200B and allow the hereinbefore described method of erecting a mobile scaffold tower 100 to be used with existing scaffold assemblies. Like parts previously described have been assigned the same reference numerals.

Referring to Figure 4(a), there is provided a retrofitting jacking point assembly indicated generally by reference numeral 400. The assembly 400 is used for affixing to an existing scaffold bar (not shown) to provide a jacking point 222 to co-operate with a

lifting mechanism (not shown). The assembly 400 comprises a clamp having a pair of semi-tubular members 402, 404 comprising interengaging complementary locking members 406, 408 along both their longitudinal edges respectively. The assembly 400 comprises a protruding tab 136 having a through hole 137, to allow a locking bolt 224 to pass through the through hole as previously described with reference to Figure 3(b).

Referring to Figure 4(b), a retrofitting jacking point assembly indicated generally by reference numeral 410 comprises a jacking point 222 connected to a clamp having a pair of semi-tubular members 412, 414 hingedly attached to one another by a hinge 416 along one of their longitudinal edges and comprising interengaging complementary locking members 418 along their other longitudinal edge respectively. The assembly 410 also comprises a protruding tab 136 and through hole 137 as previously described.

With reference to Figure 4(c), a retrofitting jacking point assembly indicated generally by reference numeral 420 is provided. The assembly 420 comprises a tubular body 422 which fits over and encases an existing vertical scaffold bar 423. The assembly 420 comprises two through holes which must be aligned with two through holes on the existing vertical scaffold bar 423 to allow two locking bolts 424A, 424B and two corresponding locking nuts 426A, 426B to locking the tubular body to the existing vertical scaffold bar 423. This embodiment would be used for more permanent retrofitting of the jacking point 420 to the existing scaffold bar 423. The jacking point 222 comprises a protruding tab 136 and through hole 137 as before.

Referring to Figure 4(d), there is provided a further embodiment of a retrofitting jacking point assembly 430. This assembly 430 is similar to the assembly 420 of Figure 4(c) however the assembly 430 may be retrofit to horizontal scaffold bars (not shown).

It will be appreciated that there are numerous well-known manners in which a jacking point assembly can be retrofit to an existing scaffold bar. Other embodiments may include quick release fasteners, grips, clasps, ties and the like.

With reference to Figure 5, a lifting mechanism indicated generally by reference numeral 500 is shown elevating a prop section 104A, wherein like parts previously described have been assigned the same reference numerals. Only one side of the prop section 104A has been illustrated, however, it will be readily understood that

the other side (not shown) of the prop 104A is also elevated by a similar lifting mechanism 500.

The lifting mechanism 500 is substantially an L-shaped lever. The lifting mechanism 500 comprises a base lever 502 which is substantially orthogonal to an elongated lever arm 504. A reinforcing strut 506 is used to strengthen the lifting mechanism 500 by bracing the base lever 502 to the elongated lever arm 504. The elongated lever arm 504 comprises a handle portion 508. A wheel 510 is fixed at the corner of the L-shaped lifting mechanism 300 where the base lever 302 meets the elongated lever arm 304. The base lever 502 comprises a lifting member 516 that engages the jacking point 222 on the prop section 104A. In this embodiment, the jacking point 222 is a simple downwardly facing hook. The handle 508 of the lifting mechanism 500 is pulled in an outward and downward direction, as indicated by arrow A, such that the wheel 510 runs along a surface 512 to elevate the prop section 104A into the elevated position as illustrated in Figure 5.

In a further embodiment (not shown), the lifting mechanism 500 may comprise a single handle, an elongated lever arm and two base levers having two lifting members 516 respectively. In this manner, one worker may engage two adjacent corner bars 1 14C, 1 14D of the upper prop section 104A to lift the corner bars 1 14C, 1 14D simultaneously and evenly in a balanced manner.

In a further embodiment, a lifting jack, such as a screw-driven jack may be used to hoist the partially erected scaffold tower comprising the platform section 102 and the upper prop section 104A. Alternatively a geared pulley system as is known to be used by mechanics to lift car engines or a hydraulic lift may be used to elevate the partially erected scaffold tower comprising the platform section 102 and the upper prop section 104A. It is of primary importance that the lifting mechanism hoists the partially erected scaffold tower in a balanced and even manner.

With reference to Figure 6, the central harness anchor point indicated generally by reference numeral 120 is shown. The central harness anchor point 120 comprises four curved co-joined attachment bars 602 and an annular collar 604. A mounting point 605 on the upper prop section (not shown) comprises a spigot 607 having a bulbous head 606 that extends upwardly from a base plate 608.

The annular collar 604 is dimensioned to form a secure fit around the spigot 607 and is held securely in place by the bulbous head 606. Thus, the anchor point 120 is rotatably secured to the upper prop section (not shown) and hence to the scaffold tower 100, 300. As the anchor point 120 is secured directly to the scaffold tower 100, 300 and not just to a wooden batten on the platform section, the anchor point 120 is secured more rigidly and is far less likely to fail in the event of a worker falling over the side of the platform section 102.

As the annular collar 604 has an inner diameter less than the outer diameter of the bulbous head 606, the anchor point 120 cannot be removed from its secured connection to the upper prop section (not shown). Each of the four curved co- joined attachment bars 602 may hold one or more lanyards or safety lines (not shown) which extend from a harness (not shown) of a worker (not shown).

Referring to Figure 7, there is a portion of a further embodiment of a scaffold tower indicated generally by reference numeral 700, wherein like parts previously described have been assigned the same reference numerals. The scaffold tower 700 comprises a platform section 102 and an upper prop section indicated generally by reference numeral 104A.

The platform section 102 comprises a substantially planar work surface 108 surrounded by a guardrail 134. A harness anchor point through hole 128 is located substantially in the central portion of the floor 108 and an access hatch 1 14 is also provided in the floor 108. A plurality of jacking points 122 protrude outwardly from each corner of the platform section 102. These jacking points 122 may be engaged by a lifting mechanism 200A, 200B, as shown discussed, to elevate the platform section 102 to a predetermined height to allow the upper prop section 104A to be manoeuvred beneath the elevated platform section 102. The jacking points 222 may be downwardly facing hooks for example. The platform section 102 further comprises a plurality of male, engaging connection means 702 that depend downwardly from the platform section 102 and are dimensioned to cooperate with the upper prop section 104A.

The upper prop section 104A comprises an X-shaped framework comprising four vertical corner bars 1 14A-1 14D. Two beams forming upper cross members 1 16B,

1 16D are diagonally arranged to criss-cross substantially at their mid-points

respectively. Two beams forming lower cross members 1 16A, 1 16C are diagonally arranged to criss-cross substantially at their mid-points respectively. A lower cross member 116A and an upper cross member 1 16B connect two of the diagonally opposed vertical corner bars 1 14B and 1 14D to one another, and the other lower cross member 116C and upper cross member 1 16D connect the other two vertical corner bars 114A and 1 14C to one another.

Each of the vertical corner bars 1 14A-1 14D further comprise a female, receiving connection means 704 which co-operates with an associated male, engaging connection means 702 on the platform section 102 to secure the platform section 102 to the upper prop section 104A. The engaging connection means 702 may be a spigot or lug and the receiving connection means 704 may be a bore in the top of the vertical corner bars 114A-1 14D.

In further embodiments, the engaging connection means 702 and the receiving connection means 704 may preferably comprise locking mechanisms such as latches and corresponding keepers, or, a pi and socket arrangement.

The anchor point 120 is mounted atop a central mast 706 of the upper prop section 104A. The central mast 706 is vertically positioned at the criss-cross intersection of the upper cross members 1 16B, 1 16D and the lower cross members 1 16A, 1 16C respectively.

The engaging connection means 702 may also be used to co-operate with the wheels (not shown) to mobilise the scaffold system 700. The wheels comprise the same receiving connection means 704 as the upper prop section 104A to allow the prop section 104A to be secured to the wheels.

Referring to Figure 8, there is provided a mobile scaffold tower according to the invention indicated generally by the reference numeral 800 comprising a platform section, similar to that previously described, indicated generally by reference numeral 102 and an uppermost prop section indicated generally by reference numeral 802. Further prop sections, similar to those previously described, are generally indicated by reference numerals 104A-104C. The scaffold tower 800 also comprises a plurality of wheels 106A-106D mounted on the lowermost prop section 104C.

The platform section 102 is mounted atop the uppermost prop section 802. The uppermost prop section 802 comprises four upper support arms 804A-804D and four lower support arms 806A-806D. The upper support arms 804A-804D extend radially outwardly and upwardly from a central mast 808. The lower support arms 806A-806D extend radially outwardly and downwardly from the central mast 808 in corresponding directions to the upper support arms 804A-804D.

Collapsible support pillars 810A-810D are arranged intermediate each upper support arm 804A-804D and each corresponding lower support arm 806A-806D respectively.

In a further embodiment, it is envisaged that such collapsible support pillars 81 OA- 810D may not be required, and support pillars may be inserted and held securely in place intermediate each upper support arm 804A-804D and each corresponding lower support arm 806A-806D by means of a clip, locking pin or other such known techniques.

A ladder segment 812 is mounted on an upper support arm 804C and a lower support arm 806C on the uppermost prop section 802.

In another embodiment, a portion of a safety rail (not shown) may run adjacent the ladder segment 812. A fall arrest system may be incorporated into a worker's safety harnesses and workers may attach their safety harness via a lanyard to the safety rail to ensure that they are protected from falling off the scaffold tower 800 as they climb the scaffold tower 800.

A plurality of jacking points 222 protrude from each outer point of the uppermost prop section 802. These jacking points 222 may be engaged by a lifting mechanism, as previously described, to elevate an engaged section and any affixed sections mounted thereon to a height above ground-level. The jacking points 222 are downwardly facing hooks for example.

The further prop sections 104A-104C are all of a substantially similar construction to the prop sections previously described and therefore for the sake of clarity and brevity, the description of these prop sections 104A-104C will be omitted.

In a further embodiment, a powered lifting mechanism such as a forklift truck may be used to hoist the partially erected scaffold tower. Tine-receiving slots may be provided in the framework of the prop sections 104A-104D. In particular, the lower cross members 1 16A, 1 16C or the upper cross members 1 16B, 1 16D of the prop section 104A-104D may comprise slots to receive a tine from a forklift truck or a piggyback forklift truck. The forklift truck may then be used to lift the partially erected mobile scaffold tower whilst a further prop section is arranged beneath the hoisted partially erected scaffold tower section.

In a further embodiment, the lifting mechanisms 200A, 200B may comprise a skid instead of the wheel 210 to allow the lifting mechanism to pivot.

In another embodiment, it will be understood that the L-shaped lever 500 does not comprise of a wheel 510. Instead, a track (not shown) with guide rails may be used to guide a pair of lugs which sit of the guide rails to rotate the L-shaped lever 500. The track may be dimensioned to only allow a controlled transition of the lugs along the rails.

In further embodiments, a chained gearing mechanism may push and pull the lugs along the rails, or pneumatic arms may be used in conjunction with the L-shaped lever to rotate the lever. In yet a further embodiment not shown, the L-shaped lever 500 may comprise an arcuate transition between the base lever 502 and the elongated lever arm 504. The arcuate transition would be used in place of the wheel 510 to provide a curved skid surface. The ground engaging portion of the arcuate transition may be dimensioned into a bladed edge to minimise friction between the arcuate transition and the ground. Moreover, a plastics material may be coated along the ground engaging portion of the arcuate transition to facilitate easier movement of the curved skid surface over the ground.

In another embodiment (not shown), a common fall arrest system is mounted just below the platform section 102. A worker will attached themselves to a line emanating from the common fall arrest system at the bottom of the constructed scaffold tower 100, 300, 700. If the worker slips and falls during their assent to the platform section 102 of the scaffold tower 100, 300, 700, the common fall arrest system will engage and prevent the worker from injuring themselves. The worker may then attached their own personal lanyard, with their own individual fall arrest

system, to the anchor point 120 before detaching themselves from the common fall arrest system. Their own individual fall arrest system will engage if the worker falls from the platform section 102 whilst working. In this manner, a worker is constantly secured to a fall arrest system during both the assent to a platform section 102 on a scaffold tower 100, 300, 700, and during the working period spent on the platform section 102 of the scaffold tower 100, 300, 700.

In the specification the terms "comprise, comprises, comprised and comprising" or any variation thereof and the terms "include, includes, included and including" or any variation thereof are considered to be totally interchangeable and they should all be afforded the widest possible interpretation and vice versa.

The invention is not limited to the embodiments hereinbefore described which may be varied in both construction and detail with the scope of the appended claims.