US20180119432A1

US20180119432A1 - Scaffold unit

Info

Publication number: US20180119432A1
Application number: US15/575,639
Authority: US
Inventors: Gregory Finlay; Peter Laurence Doljanin
Original assignee: Salita Ip Pty Ltd
Current assignee: Salita Ip Pty Ltd
Priority date: 2015-05-21
Filing date: 2016-05-11
Publication date: 2018-05-03
Also published as: EP3298214A1; WO2016183621A1; AU2016265031A1; CA2986458A1; EP3298214A4

Abstract

An extendible scaffold unit comprises at least two support platforms or two support frames (12, 14, 16), at least one of the support platforms or support frames (12, 14, 16) being movable between a lowered position and a raised position, a plurality of scissor linkages (35, 36, 37) linking one support platform or support frame (12, 14, 16) with a next support platform or support frame (12, 14, 16), each of the scissor linkages (35, 36, 37) including a plurality of legs (26, 28, 30, 32), each scissor linkage having a leg pivotally connected to or near a corner of one of the support platforms or support frames and a leg pivotally connected to or near a corner of a next support platform support frame, wherein a leg is pivotally connected at or near each corner of a support platform or support frame. By providing a leg pivotally connected at or near each corner of a support platform or support frame, the support platform or support frame is supported at or near each corner when in the raised position. This provides a stronger, more stable and more secure support to the platform/frame.

Description

TECHNICAL FIELD

The present invention relates to a scaffold unit. More particularly, the present invention relates to a scaffold unit that can be moved from a lowered or retracted configuration to a raised or expanded configuration.

BACKGROUND ART

Scaffolding is widely used in the building and construction industries. Conventional scaffolding is erected from a number of separate components. Typically, a number of posts or rods are fastened together using brackets and bolts to form the scaffolding framework, with support boards or planks being placed on the scaffolding framework to form walkways or work platforms. Erection of conventional scaffolding requires that all of the components be delivered to a building site. A scaffolding crew will then erect the scaffold. This can be time-consuming and can add to the cost of construction.
Some effort has been made in the past to develop scaffold units in which the work platforms can be moved between a lowered position and a raised position. For example, in U.S. Pat. No. 3,877,543, a scaffold unit is described which includes a horizontal platform being mounted to a plurality of vertical posts so as to be vertically movable up-and-down along the vertical posts. Rollers and drive rollers are pivotally mounted on an arm lever provided on the platform. A worm gear is coupled to the drive rollers to move the horizontal platform up and down the vertical posts by rotating the drive rollers. When a downward load is applied to the platform, the rollers and drive rollers are automatically pressed against the vertical posts so that the platform is prevented from slipping by the frictional force that is so generated. Products known as “mast climbers” have some similarity to the operating principle of the product disclosed in U.S. Pat. No. 3,877,543.
British patent number 191108619, which was filed in 1911, describes a scaffold unit in which support platforms can be raised and lowered to any desired level. This unit includes a plurality of support platforms that are connected together by a series of articulated levers known as “lazy tongs.” The platform with the series of articulated levers rests on an undercarriage mounted two wheels so that it can be easily moved to a desired location. In use, a shaft is turned to drive the articulated levers to a raised configuration. In the raised configuration, articulated levers are located below two corners of one end of each support platform. Further articulated levers are located below approximate midpoint of each support platform and the support platforms effectively cantilever outwardly from these articulated levers.
GB 759187 describes a mobile working platform in which the platform is supported by extensible lattice members that are raised by hydraulic or other means from a mobile trolley or truck. In this British patent, a single working platform is moved from a lowered position to a raised position by operating hydraulic rams to extend a pair of scissor arms that are mounted on either side of a chassis and the platform. A rack and pawl mechanism locks the platform into place.
GB 2022672 describes extensible scaffolding that uses a lazy tongs arrangement. Each of the lazy tongs arrangement comprises two pairs of levers. The levers of each pair cross each other and are pivotally connected together where they cross. A plurality of transverse structural members extend at right angles to the lengthwise dimension of the lazy tongs arrangement, with each transverse member having two guide elements mounted for guided movement along the transverse member. Each lever of the lazy tongs arrangement has a guide member attached at its ends. Two vertical scaffolding tubes extend in the same plane as the lazy tongs arrangement. To enable the lazy tongs arrangement to be extended, the lowermost of the transversely extending members carries a gearbox carrying journals for to screw threaded shafts extending parallel to the lowermost transverse member. Operation of this enables the guide members on the lowermost transverse member to move towards each other to extend the lazy tongs arrangements and raise the extensible scaffolding. As the lazy tongs arrangements extend, the respective transverse members are raised and slide upwardly along the vertical members located at either end of the transverse members. When the upper end of the structure reaches the required height, clamping bolts on the bottom transverse member are tightened to fasten the ends to the vertical scaffolding tubes. Then standing on the bottom member, the operator can tighten the bolts of the next member, and so forth, thereby allowing the operator to climb the scaffold and tighten the bolts. When in the extended position, the levers of the lazy tongs arrangements extend at an angle of between 20° and 30° to horizontal.
U.S. Pat. No. 3,820,631 describes a platform lift device which is suitable for raising workmen and equipment to elevated positions which will enable them to perform maintenance work on aircraft. This patent describes existing lifting mechanisms that use conventional scissor mechanisms to raise and lower the work platforms. This patent states that such conventional scissor mechanisms possess at least three inherent disadvantages when employed as a lifting mechanism. One disadvantage is the fact that the effective supported base area defined by the scissor ends decreases as the platform is raised, resulting in progressively less stability at higher elevations. The second disadvantage is the fact that the beams which comprise such a scissor linkage are subjected to bending loads and must therefore be relatively stiff to support loads. A third disadvantage is that the scissor linkages must be relatively long to accomplish high lift operations if done in one stage. Such long linkages necessitate a large and cumbersome storage pedestal chassis. In order to overcome these disadvantages, the lift platform of this patent has an elevating mechanism in which effectively the scissor lift arms of conventional scissor lift mechanisms are replaced with fluid power cylinders each having a ram or piston mounted to them so that struts that are pivotally connected to the chassis and the lift platform extend relative to the fluid power cylinders to thereby raise the work platforms. A mechanical interlock is used to ensure that the fluid power cylinders each extend at substantially identical values of incremental movement even if the platform is unequally loaded.
U.S. Pat. No. 4,088,203 describes an adjustable scaffold comprising a platform on base and an adjustable interconnecting support structure. The adjustable interconnecting support structure comprises a number of sets of scissor mechanisms. Lifting means, typically hydraulic cylinders with lever brackets and support brackets pivotally attached thereto, are positioned between sets of scissor connectors, rather than within them. In other words, each cylinder is attached to cross members from different sets of scissor connectors. This is stated to provide a sturdy and safe lifting mechanism is capable of lifting substantial loads of personnel and equipment. A pair of scissor mechanisms are attached to the platform.
It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.

SUMMARY OF INVENTION

The present invention is directed to a scaffold unit which may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice.
With the foregoing in view, the present invention in one form, resides broadly in a scaffold unit comprising at least two support platforms or two support frames, at least one of the support platforms or support frames being movable between a lowered position and a raised position, a plurality of scissor linkages linking one support platform or support frame with a next support platform or support frame, each of the scissor linkages including a plurality of legs, each scissor linkage having a leg pivotally connected to or near a corner of one of the support platforms or support frames and a leg pivotally connected to or near a corner of a next support platform support frame, wherein a leg is pivotally connected at or near each corner of a support platform or support frame.
By providing a leg pivotally connected at or near each corner of a support platform or support frame, the support platform or support frame is supported at or near each corner when in the raised position. This provides a stronger, more stable and more secure support to the platform/frame.
In one embodiment, the scaffold unit further comprises a drive means for raising and lowering at least one of the support platforms or support frames between the lowered position and the raised position.
The drive means is suitably mounted to the scaffold unit. This allows the drive means to raise and lower the support platforms without requiring an externally provided drive system.
In a second aspect, the present invention provides a scaffold unit comprising at least two support platforms or two support frames, at least one of the support platforms or support frames being movable between a lowered position and a raised position, a plurality of legs extending between one support platform or support frame and a next support platform or support frame, at least some of the legs having a pivotal connection to the support platform or support frame, the legs being movable during movement of the scaffold unit from the lowered position to the raised position and vice versa, the legs extending at an angle of less then 10° to horizontal when the scaffold unit is in the lowered position.
In one embodiment, at least some of the legs have a pivotal connection at or near corners of the support platform or support frame.
Suitably, the support platforms or support frames that move during raising or lowering of the scaffold unit move in an essentially vertical direction during raising or lowering. By this, it is meant that the support platforms or support frames have a negligible horizontal component to their movement during raising and lowering of the scaffold unit.
The scaffold unit may further comprise a drive means for causing at least some of the legs to pivot about their pivotal connection at or near the corners of the support platform or support frame during raising and lowering of the scaffold unit.
In some embodiments, the legs extend at an angle of less than 8° to horizontal when the scaffold unit is in the lowered position. In other embodiments, the legs extend at an angle of from 3° to 7° to the horizontal when the scaffold unit is on the lowered position. In further embodiments, the legs extend at an angle of from 4° to 6°, or even at an angle of about 4° to 5°, to the horizontal, when the scaffold unit is in the lowered position.
The scaffold unit may further comprise a further drive means to facilitate initial movement of a support platform or support frame from a lowered position. The further drive means may be selected from one or more of a column lifter, a hydraulic ram, an air bag, a pneumatic cylinder or a biasing means. In one embodiment, the further drive means comprises a biasing means that provides a biasing force to the legs when the scaffold unit is in the lowered position, the biasing force acting in a direction to assist raising the scaffold unit. In this manner, when the drive means is energised or actuated to raise the scaffold unit from a lowered position, the biasing means assists in raising the legs by applying an additional biasing force to the legs during the initial movement of the legs from the lowered position. This facilitates the initial movement of the legs from the lowered position (at which the legs are at an almost horizontal orientation) to the raised position. Further, a smaller or lower powered drive means may be used to raise the legs from the lowered position.
The biasing means may comprise one or more springs, or one or more resilient members, or one or more elastomeric or rubber members, or one or more elastomeric or rubber blocks, or one or more struts, such as one or more gas struts. The one or more springs, one or more resilient members, one more elastomeric or rubber members or one or more elastomeric or rubber blocks or one or more struts may extend in a vertical direction. In other embodiments, they may extend in a horizontal direction, or indeed they may extend at any direction that can be used to assist the initial movement from the lowered position.
In some embodiments, the further drive means contacts one support frame or support platform and another support frame or support platform when in the lowered position, but the further drive means only contacts the one support frame or support platform when in the raised position.
In some embodiments, the legs extend at an angle of greater than 80°, or greater than 85°, to the horizontal when the scaffold unit is in the raised position. In some embodiments, the legs may extend at an angle of about 86.5° to the horizontal when in the raised position.
In the second aspect of the present invention, the links that are pivotally connected to the support platforms or support frames may form part of scissor linkages.
In embodiments where the scaffold unit includes scissor linkages, the scissor linkages may comprise a first leg and a second leg, with the first leg being pivotally connected to a lower support platform or support frame at or near a corner of the lower support platform or support frame, the first leg and second leg being pivotally connected to each other at an approximate midpoint thereof, the second leg having a lower end that is reciprocally movable relative to the lower support platform or support frame, the first leg having an upper end that is reciprocally movable relative to an upper support platform or support frame, the second leg having an upper end that is pivotally connected to the upper support platform or support frame at or near a corner of the upper support platform or support frame.
In another embodiment, the scissor linkages may comprise a first leg and a second leg, with the first leg being pivotally connected to a lower support platform or support frame at or near a corner of the lower support platform or support frame, the first leg and the second leg being pivotally connected to each other at an approximate midpoint thereof, the second leg having a lower end that is reciprocally movable relative to the lower support platform or support frame, a third leg having an upper end that is pivotally connected to an upper support platform or support frame at or near a corner of the upper support platform or support frame, a fourth leg having an upper end that is reciprocally movable relative to the upper support platform or support frame, the third leg and the fourth leg being pivotally connected to each other at an approximate midpoint thereof, the third leg having a lower end that is pivotally connected to an upper end of the first leg and the fourth leg having a lower end that is pivotally connected to an upper end of the second leg.
The legs that are reciprocally movable relative to one of the support platforms or support frames may suitably be connected to one or more rollers that can move along a track or guide in or mounted to the support platform or support frame.
It will be understood that as the legs that are reciprocally movable relative to one of the support platforms or support frames are moved, those legs will also rotate or pivot relative to the support platform or support frame.
In some embodiments, the pivotal connection points of the respective legs to one of the platforms or support frames are located outwardly of the sliding ends of the other legs of each scissor linkage. This is a preferred embodiment. In another embodiment, the sliding ends of the respective scissor linkages are located outwardly of the pivotal connection points of the other ends of each scissor linkage.
In embodiments where scissor linkages are used to link a lower support platform or support frame to an upper support platform or support frame, it is preferred that the legs of the scissor linkages extend at an angle of at least 80°, or at least 85°, to the horizontal when the scaffold unit is in the raised position.
In some embodiments, the scaffold unit is fitted with a drive means to raise and lower the unit. The drive means may comprise a drive motor, such as an electric motor. The electric motor may cause a drive bar or drive member to reciprocally move relative to one of the support platforms or support frames, movement of the drive bar or drive member causing the legs to move. The scaffold unit of the present invention may desirably have the drive means mounted on board.
In some embodiments, the scaffold unit may also be provided with a braking means that can be selectively actuated to prevent raising or lowering of the scaffold unit and selectively turned off or disengaged to allow raising or lowering of the scaffold unit. In some embodiments, the braking means may engage with one or more components of the drive means.
In other embodiments, the scaffold unit may be moved from a lowered position to a raised position by suspending the scaffold unit from a crane, releasing a braking means or releasing a locking means to allow the scaffold unit to expand under its own weight and subsequently engaging the braking means or locking means when the scaffold unit is fully raised. In a further alternative, the scaffold unit may be raised and lowered by placing the scaffold unit on the ground (or on a support base), releasing a braking means or releasing a locking means, raising the scaffold unit to the raised position by use of a crane and re-engaging the braking means or the locking means to hold the scaffold unit in the raised position. Lowering may be achieved by releasing the braking means or locking means and lowering the crane to thereby lower the scaffold unit under its own weight.
In one embodiment, the scaffold unit is provided with scissor linkages and the drive bar or drive member causes at least some of the legs that are mounted for reciprocal movement relative to one of the support platforms or support frames to move relative to the support platform or support frame.
In one embodiment, the drive motor causes a ball screw or a worm gear to rotate, the ball screw or worm gear extending through a nut fixedly mounted to a drive bar or drive member, wherein rotation of the ball screw or worm gear causes the drive bar or drive member to move laterally outwardly or laterally inwardly. The drive motor may pass drive through a gear arrangement to cause rotation of the ball screw or worm gear.
In some embodiments, the scissor linkages may be moved and repositioned inwardly or outwardly relative to the support frame or support platform. In one embodiment, the support frame or support platform is provided with a plurality of spaced openings, one leg of a scissor linkage having an opening that can be brought into alignment with one of the plurality of spaced openings and a connecting pin passed through the aligned openings to thereby pivotally connect the one leg of the scissor linkage to the support platform or support frame. It will be appreciated that the other leg of the scissor linkage that is associated with that support platform or support frame can move along the support platform or support frame (for example, by use of appropriate rollers slides) and this allows easy repositioning of the scissor linkage. To facilitate repositioning, the drive means may be disconnected from the leg of the scissor linkage that can move along the support platform or support frame. This may be achieved by use of an appropriate clutch mechanism in the drive means, or use of an appropriate quick disconnect mechanism in the drive means.
Accordingly, in a third aspect, the present invention provides a scaffold unit comprising at least two support platforms or two support frames, at least one of the support platforms or support frames being movable between a lowered position and a raised position, a plurality of legs extending between one support platform or support frame and a next support platform or support frame, at least some of the legs having a pivotal connection to the support platform or support frame, the legs being movable during movement of the scaffold unit from the lowered position to the raised position and vice versa, wherein a position of the pivotal connection between a leg and the support platform or support frame can be moved between a plurality of positions. In this aspect, a plurality of scissor linkages may extend between adjacent support platforms or support frames.
In a fourth aspect, the present invention provides a scaffold unit comprising at least two support platforms or two support frames, at least one of the support platforms or support frames being movable between a lowered position and a raised position, at least one of the support platforms or support frames being provided with a support surface on which a worker can stand, the support surface including a horizontal extension movable between a retracted position and an extended position, the horizontal extension extending outwardly from the support platform or support frame when extended.
In some embodiments, the horizontal extension extends along a length of the support platform or support frame. The horizontal extension may extend towards a building located near or adjacent to the scaffold unit. In this manner, the scaffold unit can be spaced from the building to minimise the possibility of the scaffold unit coming into contact with the building and damaging the building and the horizontal extension being extended to provide a working platform that has an end located very near or in contact with the building.
In some embodiments, the scaffold unit is provided with a protective screen on one side thereof. The protective screen may automatically extend when the scaffold unit is raised. The protective screen may be made from a mesh material or a shade cloth material. The protective screen may be a removable screen.
The scaffold unit may also be provided with one or more handrails. In use when the scaffold unit is in the raised position, the handrails may extend horizontally along at least an outer side of the scaffold unit. Additional handrails may be mounted to one or more ends of the scaffold unit if the scaffold unit itself comprises an end of a scaffolding installation. The handrails may be removably mounted to the scaffold unit.
In one embodiment, the uppermost support platform or support frame may be provided with one or more handrails or guardrails that are removably mounted to a scaffold unit.
The support platform or support frame may have a support surface that enables a worker to stand or walk thereon.
The scaffold unit may also be provided with one or more stays extending between one support platform or support frame and a next support platform or support frame. The one or more stays may extend diagonally between the support platforms or support frames. The one or more stays may be extendable stays, such as telescoping stays. The one or more stays may provide additional resistance to movement of the support platforms or support frames when in the raised position. The one or more stays may include self locking means to lock the stays into an extended position when the scaffold unit is moved to the raised position.
The scaffold unit may be arranged such that a further scaffold unit can be located on top if access to a higher level is required. The scaffold unit may be provided with locking means for locking a first scaffold unit to a second scaffold unit positioned on top of the first scaffold unit. The locking means may comprise a locking bar extending through apertures located in the first scaffold unit and the second scaffold unit. The apertures may comprise aligned apertures. The locking bar may prevent relative horizontal movement and vertical movement between the first scaffold unit and the second scaffold unit.
The scaffold unit may be provided with a base unit. The base unit may comprise a separate unit upon which the scaffold unit is supported and/or connected. In one embodiment, the base unit may comprise a frame. The frame may have one or more support surfaces on which the scaffold unit may be supported. The frame may include a plurality of legs movable between a retracted position and an outward position. The plurality of legs may comprise adjustable legs. The base unit allows for convenient setup of the scaffold unit. In particular, the base unit may be located at the desired position at which the scaffold unit is to be located. The legs may be moved to the outward position and the height of the legs adjusted to account for any unevenness in the ground and to set the base unit at the correct height. A scaffold unit may then be positioned on the base unit.
In other embodiments, the scaffold unit may be provided with adjustable legs or adjustable feet that extend below the lower support platform or support frame in use.
In another embodiment, the present invention provides a scaffold unit comprising at least two support platforms or two support frames, at least one of the support platforms or support frames being movable between a lowered position and a raised position, a plurality of legs extending between one support platform or support frame and a next support platform or support frame, the legs comprising telescopically extendable and telescopically retractable legs.
In one embodiment, the telescopic legs are raised and lowered by use of hydraulic cylinders, pneumatic cylinders, or electric motors. In one embodiment, the telescopic legs are raised and lowered by use of a driving means mounted on board the scaffold unit.
In a further aspect, the present invention provides a scaffold unit comprising at least two support platforms or two support frames, at least one of the support platforms or support frames being movable between a lowered position and a raised position, a plurality of scissor linkages linking one support platform or support frame with a next support platform or support frame, each of the scissor linkages including a plurality of legs, wherein the legs of the scissor linkages extend at an angle of at least 80° to horizontal when the scaffold unit is in the raised position. In some embodiments, the scaffold unit has at least 4 sets of scissor linkages linking one support platform or support frame for next support platform or support frame.
In all embodiments of the present invention, the scaffold unit may be used in a manner that does not require the scaffold unit to be attached to a building or other structure. In this regard, the scaffold unit can provide a sufficiently stable base to enable the scaffold unit to stand by itself next to a building.
The scaffold unit of the present invention provides a scaffold unit that can be expanded from a lowered position in which the scaffold unit has a low profile, compact configuration to a raised position in which the scaffold unit enables access to higher levels. In some embodiments, the scaffold unit comprises three support platforms or support frames, being a lower support platform or support frame, an intermediate support platform or support frame and an upper support platform or support frame. In one embodiment, the drive means may be mounted to the intermediate support platform or support frame. In other embodiments, the drive means may be mounted to the lower support platform or support frame, or the drive means may be mounted to the upper support platform or support frame. In some embodiments, more than one support platform or support frame may be provided with drive means. The drive means may be effective to raise and lower all of the support platforms or support frames.
The scaffold unit of the present invention may further be provided with access stairs. The access stairs may allow access between support platforms or support frames on different levels. The scaffold unit may be further provided with rubbish chutes. The rubbish chutes may be removable rubbish chutes. The rubbish chutes may be attached to the scaffold unit when it is in the raised position and removed from the scaffold unit before it is moved back to the lowered position. The scaffold unit may be further provided with loading bays.
The scaffold unit may be provided with a locking means to lock the scaffold unit in the lowered position. This can be useful for transportation and storage of the scaffold unit.
Any of the features described herein can be combined in any combination with any one or more of the other features described herein within the scope of the invention.
The reference to any prior art in this specification is not, and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge.

BRIEF DESCRIPTION OF DRAWINGS

Various embodiments of the invention will be described with reference to the following drawings, in which:

FIG. 1 shows a perspective view of a scaffold unit in accordance with an embodiment of the present invention in a lowered position;

FIG. 2 shows a front view of the scaffold unit shown in FIG. 1;

FIG. 3 shows an end view of the scaffold unit shown in FIG. 1;

FIG. 4 shows a top view of the scaffold unit shown in FIG. 1;

FIG. 5 shows a perspective view of the scaffold unit shown in FIG. 1 in a partly raised state. In FIG. 5, the scaffold unit is approximately half extended;

FIG. 6 shows a front view of the scaffold unit shown in FIG. 5;

FIG. 7 shows an end view of the scaffold unit shown in FIG. 5;

FIG. 8 shows a perspective view of the scaffold unit of FIG. 1 in the fully raised position;

FIG. 9 shows a front view of the scaffold unit shown in FIG. 8;

FIG. 10 shows an end view of the scaffold unit shown in FIG. 8

FIG. 11 shows a front view that is generally similar to that shown in FIG. 6, but with a protective screen included;

FIG. 12 shows an end view of the scaffold unit shown in FIG. 11;

FIG. 13 shows a view similar to that shown in FIG. 3, with FIG. 13 indicating section line K-K;

FIG. 14 is a view that is similar to that shown in FIG. 2 but showing the region of detail H;

FIG. 15 shows a plan view taken along section line K-K shown in FIG. 13;

FIG. 16 is a front view, partly in cross-section, of detail H shown in FIG. 14;

FIG. 17 is a front view, partly in cross-section, of detail J shown in FIG. 11;

FIG. 18 is a front view that is generally similar to that shown in FIG. 9;

FIG. 19 is an end view is generally similar to that shown in FIG. 10 but with a protective screen included;

FIG. 20 is a detailed view of section A-A shown in FIG. 13;

FIG. 21 is a detailed view of section D-D shown in FIG. 18;

FIG. 22 is a detailed view of region L shown in FIG. 11;

FIG. 23 is a detailed view of region M shown in FIG. 18;

FIG. 24 is an end view of part of the scaffold unit as shown in FIG. 12, but in large-scale than shown in FIG. 12;

FIG. 25 is an enlarged view of detail T shown in FIG. 24;

FIG. 26 is an enlarged view of detail P shown in FIG. 19;

FIG. 27 shows an enlarged view of detail W shown in FIG. 19;

FIG. 28 is a front view of the detail shown in FIG. 27;

FIG. 29 is an end view of the lower two support frames of the scaffold unit, showing some internal details;

FIG. 30 is an enlarged view of detail AC shown in FIG. 29;

FIG. 31 is an enlarged view of detail AD shown in FIG. 18;

FIG. 32 is a perspective view of a scaffold unit in the fully raised position;

FIG. 33 is an enlarged view of detail AH shown in FIG. 32 showing an exploded view of the removable handrail;

FIG. 34 is an end view of a support platform of the scaffold unit in accordance with the present invention;

FIGS. 35 to 37 show various views of a horizontal extending support platform being extended from the support deck of the support platform shown in FIG. 34 to reach a fully extended position shown in FIG. 37;

FIG. 38 shows an end view of a lower scaffold unit in a raised position having an upper scaffold unit in a lowered position being mounted thereto;

FIG. 39 is a similar view to that shown in FIG. 38 with the locking pin engaged to lock both scaffold units together;

FIG. 40 is a similar view to that shown in FIG. 39, but with the handrails from the upper support platform or support frame of the lower scaffold unit transferred to the upper support frame of the upper scaffold unit;

FIG. 41 shows the upper scaffold unit shown in FIG. 40 being partly extended partly raised;

FIG. 42 shows an enlarged view of detail F shown in FIG. 38;

FIG. 43 shows an enlarged view of detail H shown in FIG. 39;

FIG. 44 shows an enlarged view of detail G shown in FIG. 41.

FIG. 45 shows a perspective view of a “goalpost” is used as a main connector between a scissor and a deck for all locations except where the drive frame is located;

FIG. 46 shows the goalpost of FIG. 45 in a partially disassembled state;

FIG. 47 shows the goalpost of FIG. 45 apart and in line for assembly

FIG. 48 shows a perspective view of a base unit suitable for use with a scaffold unit in accordance with the present invention;

FIG. 49 shows a plan view of the base unit shown in FIG. 48;

FIG. 50 shows a side view of the base unit shown in FIG. 48;

FIG. 51 shows an end view of the base unit shown in FIG. 48;

FIG. 52 shows a perspective view of the base unit shown in FIG. 48 with one set of legs extended;

FIG. 53 shows a perspective view of the base unit shown in FIG. 48 with two sets of legs extended;

FIG. 54 shows a perspective view of the base unit shown in FIG. 48 with a different set of legs extended;

FIG. 55 shows a cross section of the leg assembly used on the base unit shown in FIG. 48;

FIG. 56 shows a side view of another embodiment of the present invention in a lowered position. In FIG. 56, the scaffold unit is provided with a vertically extending initial lift device or further drive means;

FIG. 57 shows a side view of the scaffold unit shown in FIG. 56 in a partly raised position;

FIG. 58 shows a side view of the scaffold unit shown in FIG. 56 but with the initial lift device removed from one end and the scissor linkage removed from the other end, for clarity;

FIG. 59 shows the scaffold unit as shown in FIG. 58 in a partly extended position;

FIGS. 60 to 63 show various views of a scaffold unit in accordance with another embodiment of the present invention in which the position of the scissor linkages may be moved inwardly and outwardly relative to the ends of the scaffold unit. FIGS. 60 to 63 show the scissor linkages being in various positions;

FIGS. 64 and 65 show a scaffold unit in accordance with another embodiment of the present invention, with the scaffold unit having its fixed pivoting points at an inner part of the scissor linkages. FIG. 64 shows a scaffold unit in a lowered position and FIG. 65 shows the scaffold unit in a partly raised position;

FIG. 66 shows a side view of a scaffold unit in accordance with another embodiment of the present invention. In FIG. 66, adjacent support platforms or support frames are connected by the telescoping members;

FIG. 67 shows the scaffold unit of FIG. 66 in a partly raised position;

FIGS. 68 and 69 show a detailed view of an alternative biasing means that is used to assist in initial raising of the scaffold unit. In FIG. 68, the scaffold unit is shown in the retracted position and FIG. 69 the scaffold unit shown in a partly extended position;

FIG. 70 shows a view similar to that shown in FIG. 15, but with an alternative drive arrangement;

FIG. 71 shows a perspective view of a scaffold unit in an expanded position, with the scaffold unit having the alternative biasing means shown in FIGS. 68 and 69;

FIG. 72 shows an expanded view of the connection between the legs of the scissor mechanism of the scaffold unit shown in FIG. 71; and

FIG. 73 shows a view similar to that shown in FIG. 30 but of a scaffold unit in accordance with an alternative embodiment of the present invention. This displays an alternate connection configuration of the handrail at the front and rear of the unit

DESCRIPTION OF EMBODIMENTS

Persons skilled in the art will appreciate that the drawings have been provided for the purposes of illustrating preferred embodiments of the present invention. Therefore, it will be understood that the present invention should not be considered to be limited solely to the features as shown in the attached drawings.
FIGS. 1 to 3 show various views of a scaffold unit in accordance with an embodiment of the present invention. The scaffold unit 10 shown in FIGS. 1 to 3 is shown in the lowered position. The scaffold unit 10 can be expanded from the position shown in FIGS. 1 to 3 to a raised position or an expanded position as shown in FIGS. 8 to 10. FIGS. 5 to 7 show the scaffold unit 10 in a partly raised position. It will be appreciated that the scaffold unit 10 can also be moved (or retracted or lowered) from the raised position shown in FIGS. 8 to 10 back to the lowered position shown in FIGS. 1 to 3.
The scaffold unit 10 comprises three support frames 12, 14, 16. Support frame 12 is the lowest support frame. Support frame 16 is the upper support frame. Support frame 14 is an intermediate support frame. The support frames 12, 14, 16 each carry or support a platform, boards, planks or the like that enable a worker and/or equipment to be supported or carried thereon.
The scaffold unit 10 also includes guardrails 18, 20 that are mounted to the upper support frame 16. The guardrails 18, 20 will be described in more detail hereunder.
Each of the support frames is connected to an immediately adjacent or next support frame by use of a plurality of linkage arrangements. Each linkage arrangement includes legs that are pivotally connected at or near corners of the support frame. In the embodiment shown in the attached drawings, the linkage arrangements comprise scissor linkages.
With reference to FIGS. 5 and 6, a first linkage arrangement, generally denoted at 21, comprises leg 22 that has a lower end 23 that is pivotally connected at or near a corner 24 of support frame 12. The linkage arrangement 21 further includes a leg 26 that has a lower end 27 that is mounted to support frame 12 such that the lower end can move in a reciprocal manner relative to the support frame 12. For example, the lower end 27 of leg 26 may be mounted to a roller or slide that moves along a guide in support frame 12. Legs 22 and 26 are pivotally connected to each other at pivot connection 28. Pivot connection 28 is located at the approximate midpoint of legs 22 and 26.
The first linkage arrangement 21 further includes another leg 30 that is pivotally connected at its lower end to the upper end of leg 26. In particular, legs 26 and 30 pivotally connected at pivot connection 31. The upper end of leg 30 is mounted to support frame 14 such that the upper end of leg 30 can move into reciprocal manner relative to the support frame 14. The linkage arrangement 21 further includes another leg 32 that is pivotally connected at its upper end to support frame 14 at or near the corner 34 of support frame 14. Corner 34 of support frame 14 is positioned vertically above corner 24 of support frame 12. The lower end of leg 32 is pivotally connected at pivot connection 33 to the upper end of leg 21.
The lower support frame 12 and intermediate support frame are connected by four similar linkage arrangements, generally denoted at 21, 35, 36 and 37. Similarly, intermediate support frame 14 and upper support frame 16 are connected by four similar linkage arrangements.
As can be seen from FIGS. 5 and 6, each of the linkage arrangements 21, 35, 36, 37 has a leg that is pivotally connected at or near each corner of support frame 12 and at or near each corner of support frame 14.
As the scaffold unit 10 is raised from the lowered position shown in FIGS. 1 to 3 to the raised position shown in FIGS. 8 to 10, the legs of each linkage arrangement adopt a more vertical configuration. In particular, in the lowered position shown in FIGS. 1 to 3, the legs of the linkage arrangements may extend at an angle of less than 10° to the horizontal, particularly between four and 8° to the horizontal. Indeed, in the embodiment shown in the attached drawings, the legs of the linkage arrangements extend at approximately 4.6° to the horizontal when the scaffold unit 10 is in the lowered position. When the scaffold unit 10 is in the raised position as shown in FIGS. 8 to 10, the legs of the linkage arrangements extend at an angle of greater than 80°, more suitably at an angle greater than 85°, to the horizontal. Indeed, in the embodiment shown in the attached drawings, the legs of the linkage arrangements extend at an angle of 86.5° when the scaffold unit 10 is in the raised position. As the legs of the linkage arrangements are almost vertical when the scaffold unit 10 is in the raised position, the linkage arrangements can support significant weight. Further, the almost vertical linkage arrangements are located at or near each corner of the respective support platforms of the scaffold unit 10. This provides good stability to the scaffold unit 10 when it is in the raised position.
Scaffold unit 10 may also be provided with diagonal stays 38, 40 that extend from one corner of support frame 12 to a diagonal corner of support frame 14. As best shown in FIGS. 5 and 8, the diagonal stays are located near one side of the scaffold unit 10. In this way, a more open space is provided at the other side of the scaffold unit 10, in order to provide a clear or more open space for workmen to access a building from the scaffold unit 10. The stays 38, 40 may comprise telescoping stays so that the stays can expand or lengthen as the scaffold unit 10 is raised and the stays can retract or shorten as a scaffold unit 10 is lowered. The stays 38, 40 are suitably pivotally mounted at their respective ends to the respective parts of the lower support frame 12 and intermediate support frame 14. Similar stays 42, 44 are provided between the intermediate support frame 14 and the upper support frame 16. The stays provide additional rigidity to the scaffold unit 10 when it is in the expanded position.
FIG. 12 shows a scaffold unit 10 that is fitted with a protective screen 46. Protective screen 46 extends between the lower support frame 12 and the intermediate support frame 14. Similarly, a protective screen 48 extends between the intermediate support frame 14 and the upper support frame 16. The protective screens 46, 48 may be made from a mesh material or a shade cloth type material or indeed from any material known to be suitable for forming protective screens for use in scaffolding. The protective screen may be made from a single piece of material, or it may be made from two pieces of material, or indeed it may be made from more than two pieces of material. Protective screens 46, 48 are provided to minimise the risk of workmen dropping tools or other objects from the support platforms. They also provide enhanced protection against falling for workers working on the support platforms 12, 14. It will be appreciated that the scaffold unit 10 shown in FIG. 12 is only partly raised. As a result, the protective screens 46, 48 shown in FIG. 12 have not been pulled taut and they tend to bag as a result. Further details of the protective screens will be provided hereunder with reference to FIGS. 24 to 26.
FIG. 15 shows a top view of the intermediate support frame 14, but with the support platform removed for greater clarity. The support frame 14 comprises a plurality of frame members. In particular, the support frame 14 includes end frame members 50, 52 and side frame members 54, 56. The end frame members 50, 52 and the side frame members 54, 56 may be in the form of beams, such as steel beams or aluminium beams or indeed beams made from any other material having comparable strength to aluminium or steel, including C-section beams, or they maybe in the form of hollow section steel beams, such as rectangular hollow section (RHS) beams. The side frame members 54, 56 may be C-section beams. The support frame 14 is also provided with corner castings 58, 60, 62, 64. The corner casting is may be in the form of ISO compliant corner castings for shipping containers or similar in order to facilitate movement and transportation of the scaffold unit. The respective beams and corner castings are welded together to form a strong rectangular frame. Alternatively, the respective beams and corner castings may be bolted together, riveted together or joined using a combination of bolts and rivets. Other fasteners or fastening systems known to the person skilled in the art may also be used.
The frame includes intermediate frame members 66, 68. Intermediate frame members 66, 68 extend between the side frame members 54, 56 and are welded thereto. The intermediate frame members 66, 68 are used to form part of a housing for an electric motor 70. Electric motor 70 has an output shaft (not shown) that is connected to a gearbox 72. The output shaft from gearbox 72 connects to a T-gearbox 74. T-gearbox 74 is used to rotate ball screws 76, 78. The distal ends of the ball screws 76, 78 are retained in bearing housings 80, 82 which allow the ball screws 76, 78 to rotate whilst also holding the ends of the ball screws in place. The bearing housings 80, 82 mounted to the intermediate frame 14.
The intermediate frame 14 also houses drive bars 84, 86. Drive bars may be in the form of beams or RHS sections. Drive bar 84 has rollers 88, 90 attached thereto. Similarly, drive bar 86 has rollers 89, 91 attached thereto. The rollers 88, 90, 89, 91 are mounted to roll in the channel formed by the C-beam of side frame members 54, 56. The reciprocally movable ends of the legs 30, 92 are also mounted to drive bar 84 (leg 92 is part of the linkage extending between the intermediate support frame 14 and the upper support frame 16. Leg 92 is also shown in FIG. 6). These legs are also mounted to another roller 94. Roller 94 also rolls in a guide channel formed by the C-beam of side frame member 56. The other reciprocally movable legs of the linkage arrangements are also mounted to the respective drive bars 84, 86 in a similar manner.
The drive bars 84, 86 include an aperture through which the respective ball screws 76, 78 can pass. Ball screw nuts 96, 98 are affixed to the drive bars such that the ball screw 76, 78 engage with the ball screw nuts 96, 98. In this manner, when the ball screws 76, 78 are caused to rotate by operation of the electric motor 70, interaction between the ball screws and their respective ball screw nuts causes the drive bars 84, 86 to move along the ball screws 76, 78. Depending upon the operation of the electric motor, this causes the drive bars 84, 86 to move either outwardly or inwardly, thereby causing the scaffold unit 10 to either raise or lower.
The legs 32, 93 that are pivotally connected at or near the corner 34 of the intermediate support frame 14 are also shown in FIG. 14. As can be seen, the outer ends of legs 32, 93 are mounted about a pivot pin 99 which, in turn, is connected to a connecting bar 100. Connecting bar 100 also carries a pivot pin 101 that is used to connect the similar pivoted legs (not numbered in FIG. 14 for clarity purposes) on the other side of the support frame 14. Pivot pins 99, 101 are pivotally mounted to the respective side frame members 54, 56.
The arrangement shown in FIG. 15 advantageously allows a single drive motor to raise or lower both intermediate support platform 14 and upper support platform 16. In particular, if the scaffold unit 10 is in its lowered position (as shown in FIG. 1) and the drive motor 70 is energised to cause the drive bars 84, 86 to move outwardly, this causes the reciprocally movable ends of legs 32 and 92 (and the other similarly reciprocally movable ends of the legs of the other linkage arrangements) to move outwardly. As a result, the linkage arrangements between the intermediate support frame 14 and lower frame 12 start to extend. Similarly, and at the same time, the linkage arrangements between the intermediate support frame 14 and the upper support frame 16 are also caused to extend. This results in the spacing between the support frames 12, 14 and 16 increasing as the scaffold unit is raised. This enables a compact and yet robust drive mechanism to be used to raise and lower the scaffold unit 10.
It will also be appreciated that the drive means may be arranged on the lower support platform or support frame or on the upper support platform or support frame. Indeed, drive means may be provided on two or more of the support platforms or support frames.
Although use of an electric motor 70 is preferred in order to raise and lower the scaffold unit, the electric motor may be replaced by any other known apparatus to cause rotation of the shaft. For example, the electric motor may be replaced by a hand operated wheel, by a nut that can be caused to rotate by use of an appropriate rattle gun or electric drill having a suitable socket connection, or indeed by any other known system for causing rotation of a shaft. In embodiments where an electric motor is used, the electric motor may be powered by an external electricity supply or it may be powered by an on-board battery supply.
In some embodiments, the scaffold unit may also be provided with a braking means that can be selectively actuated to prevent raising or lowering of the scaffold unit and selectively turned off to allow raising or lowering of the scaffold unit. The braking means may engage with one or more components of the drive means.
It will also be understood that there may be a number of alternative drive systems or drive arrangements that may be used in the scaffold unit of the present invention. Indeed, the present invention encompasses any drive system or drive arrangement or drive means that allows the scaffold unit to be raised and lowered.
FIG. 16 shows an enlarged cross sectional view of detail H shown in FIG. 14. In FIG. 16, the scaffold unit 10 is in the lowered position. The reciprocally movable end of leg 92 that is mounted to roller 94 can clearly be seen. Similarly, the reciprocally movable end of leg 26 can be clearly seen. These are mounted to roller 110 that is adapted to move along a guide formed in a channel in a side of frame member of lower support frame 12. Leg 32 can also be seen. Similarly, the reciprocal movable end of leg 108 can be seen. This leg is mounted to roller 112. Roller 112 is mounted so that it can move along a channel or guide formed in a side frame member of upper support frame 16. The other linkage arrangements are similarly arranged.
In order to assist in moving the legs of the linkage arrangements from the lowered position in which the legs extend in an almost horizontal direction (in the embodiment shown in FIG. 16, the legs extend at an angle of 4.6° to horizontal), biasing means 114, 115, 116, 117 are provided. Biasing means 114, 116 are shown in FIG. 16, with all biasing means 114, 115, 116 and 117 being shown in FIG. 15. The biasing means may be in the form of blocks of rubber or elastomer. In other embodiments, the biasing means may comprise one or more springs. When the scaffold unit 10 is in the lowered position as shown in FIG. 16, the drive bars 84, 86 contact and compress the biasing means 114, 115, 116, 117. When it is desired to raise the scaffold unit 10, the drive motor 70 is operated and this applies a force to the drive bars 84, 86. As the drive bars 84, 86 are also compressing the respective biasing means at this stage, the biasing means also provide an additional force to assist in pushing outwardly on the drive bars 84, 86. Thus, the initial pushing force provided to the drive bars by the drive motor is enhanced by the reactive force caused by compression of the biasing means by the drive bars. Thus, at the very beginning of outer travel of the drive bars 84, 86, a force that is larger than the force provided by the drive motor alone is applied. This assists in moving the legs from their almost horizontal configurations. As the drive bars move outwardly, the legs move to a more vertical orientation. It has been found that once the drive bars have been moved sufficiently outwardly to clear the biasing means, the legs have a sufficiently vertical orientation to allow the power of the drive motor to continue raising the legs. Independent engineers who provided a confidential review of the drive system of the present invention commented that the legs would not be able to be lifted by the drive motor if the closed angle was less then 10.5°. The present inventors have shown that this is not the case.
FIG. 17 shows an enlarged view of detail J shown in FIG. 11. This is a view that is similar to the view shown in FIG. 16, but with the scaffold unit 10 being raised to about a halfway position. As can be seen from FIG. 17, the drive bars 84, 86 are now clear of the biasing blocks 114, 116. The more vertical position of legs 30 and 92 can also be seen.
FIG. 20 shows an enlarged view taken along section A-A and section B-B of FIG. 12 and FIG. 21 shows an enlarged view taken along section C-C and section D-D of FIG. 18. These figures show one embodiment by which the guardrail 18 may be mounted to the upper support frame 16. The guardrail 18 includes a generally vertical extending post 120. A button 122 is mounted to an upper part of the vertical post 120. Button 122 operates a cable 124 that extends through vertical post 120. Cable 124 passes over fixed cable guides 126, 128, 130. The lower end of cable 124 is connected to a movable tongue 132. The movable tongue 132 is housed in a housing 134 at lower end of the post 120. Housing 134 may comprise the vertically extending lower part 222 of the post 120 (see FIG. 38). Housing 134 is received in a sleeve or bracket 136 that is welded to side frame member 138 of the upper support frame 16. The sleeve or bracket 136 has an open bottom. The low section of housing 134 forms a stop member 140.
In order to mount the guardrail 18 to the upper frame member 16, the button 122 is depressed, which causes tongue 132 to be retracted. This is shown in FIG. 20. The housing 134 is then inserted into the sleeve or bracket 136 until tongue 132 is positioned below the lower end of sleeve or bracket 136. The button 122 may then be released, which causes the tongue 132 to be released and to extend outwardly, as shown in FIG. 21. This results in the tongue 132 retaining the housing 134 (and the vertical post and also the guardrail 18) in the sleeve or bracket 136. In order to remove the guardrail 18 from the upper frame member 16, the button is pressed again, which retracts the tongue, thereby enabling the guardrail 18 to be lifted out of the sleeve 136. It will be appreciated that the tongue may be biased to the extended position by use of a biasing means 133. Biasing means 133 may comprise a rubber block or a spring.
It will also be appreciated that the guardrail 18 may be provided with a number of vertical posts 120. A plurality of the vertical posts may be provided with the locking means as described above. It will also be understood that the guardrail may be connected to the upper platform by a number of other mechanisms or connections. For example, the guardrail 18 may be simply bolted to the upper platform. Alternatively, the guardrail 18 may be received in one or more openings or pockets that present in the upper surface of the upper platform or support frame or that are attached to the side of the upper platform or support frame.
FIGS. 22 and 23 show operation of the stays. Stay 38 comprises a telescopically extendable stay having a hollow portion 140 that can telescopically receive rod 142. Rod 142 is pivotally connected at its upper end 144 to intermediate support frame 14. Similarly, although not shown, the lower end of hollow portion 140 is pivotally connected to the lower support frame 12. As the scaffold unit 10 continues to be raised from the part raised position shown in FIG. 22 to the fully raised position shown in FIG. 23, the rod 142 continues to extend outwardly from hollow portion 140 until the scaffold unit 10 reaches the fully raised position. The stay 38 may be provided with a self locking mechanism such that when the stay 38 is fully extended, the rod 142 automatically locks in position relative to the hollow portion 140. The stays result in increasing the rigidity of the scaffold unit 10 when in the raised position.
FIGS. 24 to 26 show various views of one way of ensuring that the protective screen 46 can be guided and retained in position. In FIG. 24, the scaffold unit 10 is partly raised, as shown in FIG. 6. A hand rail 150 is mounted at the pivot points where the upper and lower legs of the linkage 35 are pivotally connected to each other. The protective screen 46 may be in the form of a fabric or mesh (such as a shade cloth type mesh) and it is located behind the handrail 150. A guide 151 guides the mesh inwardly. This acts to retain the middle part of the protective screen 46 in position. As the scaffold unit 10 is raised, the mesh remains behind the handrail 150 but is stretched toward, as shown in FIG. 26.
In some embodiments, the lower end intermediate support frames 12, 14 may be provided with an incorporated mid-rail and toeboard. FIGS. 27 and 28 show these features. FIGS. 27 and 28 include an enlargement of detail W shown in FIG. 19. The mid-rail 152 and toeboard 154 can be seen in FIG. 28. The mid-rail 152 is supported by a number of generally vertical posts, one of which is shown at 156. The mid-rail and toeboard may be removable from the scaffold unit.
FIG. 29 shows an enlarged view of detail AB shown in FIG. 13. This shows the lower support platform 12 and the intermediate support platform 14 in the lowered position. It will be appreciated that upper support platform 16, which can be partially seen in FIG. 29, will be directly above intermediate support platform 14. The support platform 12 supports a deck 160. Similarly, support platform 14 supports a deck 162. The decks provide a support surface or walking surface on which workers and equipment can stand or walk. The linkage arrangements 35, 37 fold up and partly fit into the space caused by the deck 160 acting as a spacer between the lower support frame 12 and intermediate support frame 14. Springs 164, 166 push against the lower support frame 12 in order to operate and positively engage the locking mechanism, as will be described in more detail with reference to FIGS. 42 and 44. Handrail 150 also fits into this space, as can be more clearly seen in FIG. 30. Alternatively, one or more locking bars may be used to lock the scaffold unit in the retracted position for transport and storage.
FIGS. 32 and 33 show expanded detail of how the legs of the scissor linkages are pivoted together and how the handrail is mounted thereto. With reference to FIGS. 32 and 33, lower leg 170 is pivotally connected to upper leg 172. Similarly, lower leg 174 is pivotally connected to upper leg 176. The lower are pivotally connected to each other at pivot point 178. Similarly, upper legs 172, 176 pivotally connected together at pivot point 180.
The legs 170, 172 are pivotally connected together by forming aligned holes in those links. A pin 182 extends through the holes and a locking pin 184 is used to retain the pin 182 in position. It will be understood that the legs 170, 172 can pivot around pivot pin 182. Bushings, such as nylon bushings, bronze bushings or bushing are made from any other suitable bushing material 186, may be inserted in the openings in the legs in order to minimise friction and noise during pivoting. The handrail 150 may be positioned inside a bracket 188 that can be pivotally connected to pivot pin 182. In this regard, an opening 190 may be formed in the head of pivot pin 182 and an appropriate fastening pin (not shown) may be used to connect the handrail bracket 188 to the pivot pin 182. The handrail 150 may be slidable within the bracket 188 to enable the brackets to slide along the handrail whilst the scaffold unit is being raised or lowered. In other embodiments, the handrail 150 is locked into position. Bracket 188 may swing open to enable easy installation and removal of handrail 150.
FIGS. 34 to 37 show operation of a horizontally extendable deck. In particular, lower support frame 12 is provided with a deck 160. Deck 160 may have a horizontally extendable portion. As shown in FIG. 35, the horizontally extending portion 200 can extend sideways from the deck 160. FIG. 36 shows the extending portion 200 of deck 160 being further extended, with FIG. 37 showing the extending deck 200 being at its maximum horizontal extension. As can be seen, use of a horizontal deck having a portion that is both extendable and retractable can allow for the deck to extend horizontally to fill in any gap or space between the scaffold unit 10 and a building that is adjacent to the raised scaffold unit 10. In this manner, the scaffold unit 10 can be spaced from the building at a desired minimum distance so that undesired contact between the scaffold unit 10 and the building is avoided. This helps to avoid causing damage to the building, particularly in instances where the scaffold unit 10 is being used adjacent to a completed building (for example, for maintenance purposes or cleaning purposes).
Although not shown in FIGS. 34 to 37, the deck 160 will have a hollow having a side opening through which the extendable portion 200 of the deck can be extended and retracted. The extendable portion 200 of the deck may be extended and retracted using a drive means, such as a drive motor. Alternatively, the extendable portion 200 of the deck may be manually moved inwardly and outwardly. One or more locking arrangements, such as locking pins that fit into apertures in the deck 160 and the extendable portion 200 of the deck, may be used to lock the extendable portion of the deck in position.
The other support platforms may also be provided with decks that can extend and retract horizontally.
FIGS. 38 to 41 show a guard rail 18, 20 being moved from a lower scaffold unit 10 to an upper scaffold unit 210. In FIG. 38, the lower scaffold unit 10 is in its fully raised position. If it is desired to obtain access to even higher areas, a second scaffold unit 210 that is essentially identical to scaffold unit 10 is mounted to the upper support frame 16 of lower scaffold unit 10. As can be seen from FIG. 38, the guard rail 18 has a vertical support post 120. The lower end of the vertical support post 120 extends inwardly at 220 and then extends vertically downwardly again at the very end, as shown at 222. In this way, a major part of the length of support post 120 is spaced outwardly from the upper support frame 16. This provides sufficient space to enable the upper scaffold unit 210 to be positioned on top of the upper support frame 16 of the lower scaffold unit 10 without first having to remove the guardrails 18 and 20.
Once the upper scaffold unit 210 has been placed on the lower scaffold unit 10, the scaffold units 10, 210 may be locked together (as will be described with reference to FIGS. 42 to 44). The guardrails 18, 20 may then be unlocked (as described with reference to FIGS. 20 and 21) and repositioned to be mounted into the appropriate support brackets mounted to the sides of the upper support frame of upper scaffold unit 210. This is shown in FIG. 40. The upper scaffold unit 210 may then be raised, as shown in FIG. 41. In FIG. 41, the upper scaffold unit 210 is partly raised.
In order to lock the upper scaffold unit 210 to the lower scaffold unit 10, an opening 230 that leads into a passage 232 that is formed in one of the members of upper support frame 16 or in the corner castings of the upper support frame 16. The upper scaffold unit 210 includes a lower support frame 234, an intermediate support frame 236 and an upper support frame 238. Each of the support frames includes member corner castings that have passages 240, 242 and 244. Passage 244 has an upper opening 246 of decreased diameter or size. Similarly, passage 244 has an upper opening 248 of decreased diameter or size. A biasing spring 250 is mounted in passage 240. Another biasing spring 252 is mounted in passage 242. A locking bar 254 having a top cap 256 and a bottom cap 258 is positioned so that it extends through aligned passages 240, 242, 244. It will be appreciated that the upper scaffold unit 210 shown in FIG. 42 is in the lowered position.
Once the upper scaffold unit 210 is positioned on the lower scaffold unit 10, as shown in FIG. 42, the locking bar 254 is actuated by rotating by 90°. The top cap 256 and the bottom cap 258 have a narrow side and a longer side. Rotating the bar by 90° brings the narrow side into alignment with the narrow openings 230, 231 and 246. This enables the locking bar 254 to move downwardly such that bottom cap 258 passes through aligned narrow openings 230, 231, as shown in FIG. 43. This acts to lock the lower scaffold unit 10 to the upper scaffold unit 210. It will be appreciated that similar locking mechanisms are provided on each corner of the scaffold units. The upper scaffold unit may then be extended/raised, as shown in FIG. 44. In some embodiments, the lower end of the locking bar 254 may engage at its lower end with the lower scaffold unit. For example, the lower end of the locking bar 254 may be restricted from moving further downwardly once it is moved into a locking position. In this embodiment, it may be possible to omit the springs shown in FIGS. 42 to 44 and in FIG. 29.
FIGS. 45 to 47 show the connection of the legs of the scissor linkages that are pivotally connected at or near the corners of the support frames. For example, in FIG. 45, leg 22 (refer to FIG. 6) and the corresponding leg 270 on linkage 36 are interconnected by a rod 272. Rod 272 is welded to respective scissor arms 22, 270. Rod 272 is a hollow rod that can receive an insert 274. This is shown in FIG. 46. Insert 274 comprises a hollow locking insert 276 that is fitted with a threaded insert 278. Bushes 280, such as nylon bushes, are fitted to an opening 284 in scissor leg 22. The locking insert with fitted threaded insert 278 is inserted into the hollow end of rod 272 prior to welding the rod to 72 to the scissor arms 22, 270. An appropriate threaded locking pin or locking bolt, such as pivot pin 99 or 101 (see FIG. 15) is then passed through the opening 284 and bushes 280, 282 to thereby pivotally connect the scissor arms 22, 270 to the lower frame members.
FIGS. 48 to 51 show various views of a base unit 300 in accordance with the present invention. The base unit 300 comprises a frame made up of frame members 302, 304, 306 and 308 that are welded or bolted together to form a generally rectangular frame. Support surfaces 310, 312, 314 are welded to the frame at locations at or near the corners of the frame. The frame may also be provided with corner castings, one of which is numbered at 318, to assist in transport of the frame.
Each of the support surfaces 310, 312, 314, 316 is provided with an opening 350. Opening 350 can receive respective locking bars 254 (refer to FIGS. 42 to 44) which allow the scaffold unit placed on the base unit 300 to be securely fastened to the base unit in a manner that is similar to that as described with reference to FIGS. 42 to 44.
The frame is also provided with four leg assemblies, with each leg assembly being located near a corner of the frame. One leg assembly is numbered at 320 in FIG. 49. The leg assembly 320 includes a first leg 322 and a second leg 324. Both legs 322, 324 can pivot about 90° from the retracted position shown in FIGS. 48 to 51 to an extended position in which the legs extend generally vertically. Leg 322 is fitted with a foot 326. Similarly, leg 324 is fitted with a foot 328. The other leg assemblies in the other corners of the frame are similar.
FIG. 55 shows more detail of the leg assembly 320. In FIG. 55, the leg 322 has been pivoted to the extended position in which the leg 322 extends in a generally vertical direction. Leg 324 is still in its retracted position in which it is positioned in a generally horizontal orientation.
As can be seen from FIG. 55, leg 326 comprises an outer tube 330 having a nut 332 welded position therein. An inner threaded rod 334 is mounted in a bearing block 336. The inner threaded rod 334 can rotate relative to the outer tube 330. This causes the outer tube 330 to move along the inner threaded rod 334 to thereby adjust the length of the leg 322.
Returning to FIG. 49, leg 322 is pivotally mounted in bracket 340. Similarly, leg 324 is pivotally mounted in bracket 342. Leg 324 is somewhat shorter than leg 322.
FIG. 52 shows the longer legs 322 mounted at the end of the base unit near frame member 308 being extended, whilst the legs at the other end of the base unit near frame member 304 remained retracted. In this configuration, the end of the base unit at 304 can rest on the ground whilst the feet of the long legs 322 at the end of the base unit near 308 can also rest on the ground. This allows the base unit to be positioned horizontally on sloping ground having a reasonable slope.
FIG. 53 shows the longer legs 322 at end 308 being extended and the shorter legs 324 at end 304 also being extended. This allows the base unit to be horizontally set on gently sloping ground whilst also allowing the height of the base unit to be set at a desired level.
FIG. 54 shows an embodiment in which legs 322 mounted near frame member 304 have been extended. This provides for the shorter legs at that end of the base unit to be extended whilst the other legs at the other end of the base unit remain retracted. This allows the other end of the base unit to rest on the ground whilst the short extended legs at the end near frame member 304 rest on the ground. In this configuration, the base unit can be securely positioned on ground having a gentle slope.
It will be appreciated that the operator will select the legs to be extended (the shorter legs or the longer legs) and then adjust those legs to the desired height to ensure that the top of the base unit 300 is level/horizontal and that it is at the correct height such that the extended scaffold unit placed on top will have its support decks at the required height, for example at the required height necessary to align the support decks with floor levels of a building. FIGS. 56 to 59 show various views of a scaffold unit in accordance with another embodiment of the present invention. Referring initially to FIGS. 56 and 57, the scaffold unit 400 shown in these drawings includes a first support platform or support frame 402 and a second adjacent support platform 404. It will be appreciated that further support platforms or support frames may be mounted above frame 404 or below frame 402. Scissor linkages 406, 408, which may be essentially identical to the scissor linkages as described with reference to FIGS. 1 to 10, connect the support frame 402 to the support frame 404. In some embodiments, there will be four scissor linkages connecting each support frame to an adjacent support frame. A drive mechanism similar to that shown in FIG. 15 may be used to raise and lower the scissor linkages 406, 408.
In order to assist with the initial movement of the scaffold unit from the lowered position, further drive means in the form of initial lift devices 410, 412 are positioned between frame 402 and frame 404. The initial lift devices can extend in an essentially vertical direction. For example, as shown in FIG. 56, when in the lowered position, the initial lift devices 410, 412 have a short vertical extent. When extended, as shown in FIG. 57, the initial lift devices 410, 412 have a much larger vertical extent. In order to move the scaffold unit 400 from the lowered position to the raised position, the initial lift devices 410, 412 may be actuated to cause the support frame 404 to be raised away from the support frame 402. This, of course, also causes vertical extension of the scissor linkages 406, 408. The drive means to drive the scissor linkages may be actuated or may become more effective at raising the scissor linkages once the legs of the scissor linkages become more vertical, for example, once those legs are positioned at an angle of greater than 10° to the horizontal, to continue raising of the scaffold unit.
The legs of the scissor linkages may extend at an angle of less than 10° to the horizontal when the scaffold unit 400 is in the lowered position. The initial lift devices 410, 412 may replace the biasing means 114, 115, 116, 117 shown in the drive means of FIG. 15. Alternatively, the initial lift devices 410, 412 may assist the biasing means shown in FIG. 15 with the initial raising of the support frame.
In some embodiments, the support frame 404 may move away from the top of the initial lift devices 410, 412 as the support frame 404 moves to the raised position. In this regard, the initial lift devices 410, 412 may have a maximum vertical extension that is less than the distance between the support frames 402, 404 in the fully raised position. It will be appreciated that the lower end of the initial lift devices 410, 412 may be connected to the support frame 402 but the support frame 404 might only rest on the initial lift devices 410, 412 when in the lowered position.
It will also be appreciated that FIGS. 57 and 59 show the scaffold unit 400 in a partly raised position. When in the fully raised position, the legs of the scissor linkages 406, 408, may extend at an angle of greater than 80° to horizontal.
FIGS. 60 to 63 show a scaffold unit 420 in accordance with another embodiment of the present invention. The scaffold unit 420 comprises a support frame 422 and an adjacent support frame 424. Although not shown in FIGS. 60 to 63, it will be appreciated that further support frames may be included in the scaffold unit 420. In one embodiment, the scaffold 420 may include 3 support frames. The support frame 422 includes a side beam that has a plurality of spaced openings, some of which are numbered at 426, 428, 430, 432, 434.
Scissor linkages 436, 438 connect support frame 422 to support frame 424. The scissor linkages 436, 438 may be similar to the scissor linkages as described with reference to the embodiment shown in FIGS. 1 to 10. In particular, scissor linkage 436 includes a leg 440 that is pivotally connected at its lower end to the support frame 422. Scissor linkage 436 also includes a leg 442 that is pivotally connected at its upper end to support frame 424. Scissor linkage 436 has a leg 444 that has a lower end that is movable inwardly and outwardly along a track or guide of the support frame 422. Scissor linkage 436 also includes a leg 446 that has an upper end that is movable inwardly and outwardly along a track or guide of the support frame 424.
In the embodiment shown in FIGS. 60 to 63, the location of the scissor linkages 436, 438 are adjustable and can be moved to a desired location, depending on the site requirements. In order to connect the scissor linkage 436 to support platforms 422, 424, openings in the respective ends of legs 440, 442 are aligned with respective openings formed in the side beams of support frames 422, 424. Pivot pins 448, 450 are then inserted through the aligned openings to thereby pivotally connect the respective ends of legs 440, 442 to the respective support frames 422, 424. The inwardly/outwardly movable ends of legs 444, 446 can slide along their respective guides or tracks during repositioning of the scissor linkages inwardly or outwardly. The drive mechanism that drives the scissor linkages to raise and lower the scissor linkages may be disconnected during this repositioning process.
In FIG. 60, the scissor linkage 436 is shown to be pivotally connected to opening 430. Scissor linkage 438 is similarly positioned at the other end of the scaffold unit 420. In FIG. 61, the scissor linkage 436 is pivotally connected to opening 428. Scissor linkage 438 is similarly positioned at the other end of the scaffold unit 420. In FIG. 62, the scissor linkage 436 is pivotally connected to opening 426. Scissor linkage 438 is positioned such that it is pivotally connected at opening 452. As can be seen from FIG. 62, scissor linkage 436 is positioned at an outer end of the scaffold unit 420 whereas scissor linkage 438 is positioned inwardly from an outer end of the scaffold unit 420. In FIG. 63, scissor linkage 436 is pivotally connected to opening 430 and scissor linkage 438 is pivotally connected to opening 452. Thus, the position of the respective scissor linkages can be moved and located in accordance with specific site requirements for any particular job.
FIGS. 64 and 65 show side views of a scaffold unit 470 in accordance with another embodiment of the present invention. The scaffold unit 470 includes support frame 472 and support frame 474. Scissor linkages, 476, 478 connect support frames 472, 474. In contrast to the embodiment shown in FIGS. 1 to 10, the scissor linkages are not located directly under corners of the support platforms. Rather, they are mounted slightly inboard from the corners. Further, the fixed pivot points of the scissor linkages are located at the inner part of the scissor linkages. For example, the fixed pivot points of scissor linkage 476 are shown at 480, 482 and the fixed pivot connections of scissor linkage 478 are shown at 484, 486. Appropriate changes to the drive mechanism shown in FIG. 15 can be made so that the inwardly and outwardly movable ends of the scissor linkages are raised by moving those ends inwardly and lowered by moving those ends outwardly.
FIGS. 66 and 67 show a scaffold unit 500 having support frames 502, 504. Vertical telescoping members 506, 508 extend between the support frames 502, 504. The vertical telescoping members 506, 508 are suitably connected at either end to the respective support frames 502, 504. The vertical telescoping members 506, 508 may comprise hydraulic cylinders or hydraulic rams, pneumatic cylinders or pneumatic rams, or column lifters. In this embodiment, motive power, such as a source of pressurised hydraulic fluid or pressurised pneumatic fluid, or an electric actuator, may be mounted on the scaffold unit 500. Alternatively, the scaffold unit 500 may be connected to external sources of pressurised fluid or electrical power. The vertical telescoping members 506, 508 may be operated such that they extend to thereby raise the scaffold unit 500 and retract to thereby lower the scaffold unit 500.
FIGS. 68 and 69 show side views of one end of a scaffolding unit in accordance with another embodiment of the present invention. The embodiment shown in FIGS. 68 and 69 includes three support platforms 602, 604, 606 that are interconnected by scissor linkages, some of which are shown at 608, 610. The scaffold unit 600 different is from that shown in embodiments in that a gas strut 612 is mounted at 614 to part of the upper support platform. The gas strut 612 extends downwardly in a generally vertical direction. The gas strut 612 comprises a two-stage gas strut. A lower and 616 of the gas strut 612 is provided with an abutment 618 that rests on an abutment surface 620 that is mounted to a lowered chassis member 622 of the scaffold unit when the scaffold unit 600 is in a retracted condition. This is best shown in FIG. 68. When the scaffold unit is in the retracted condition, the two-stage gas/612 is fully compressed.
FIG. 69 shows the scaffold unit 600 in a partly extended condition. As can be seen, as the drive units starts to extend the scaffold unit from the retracted condition, the gas strut 612 applies an upwardly directed biasing force to the upper platform 606. This assists the drive unit in initially moving the scaffold unit out of the fully retracted condition. As can be seen in FIG. 69, as the scaffold unit continues to extend, the gas strut 612 also extends so that the intermediate portion 624 and the lower portion 626 of the gas strut 612 become fully extended. When the gas strut 612 is fully extended, the scaffold unit 600 has been extended to a position that is sufficiently high such that the drive unit can continue to extend and raise the scaffold unit without assistance of the gas strut. As shown in FIG. 69, as the scaffold unit 600 continues to extend, the abutment member 618 moves upwardly and away from the abutment surface 620. When the scaffold unit 600 is moved to an extended position to the retracted position, the abutment member again comes into contact with the abutment surface 620 and the gas strut 612 become is compressed as the scaffold unit continues to retract.
In the embodiment shown in FIGS. 68 and 69, gas struts may be mounted at or near each corner of the upper platform. Alternatively, a smaller number of gas struts may be used.
In the embodiment shown in FIGS. 68 and 69, it may be possible to omit the biasing blocks 114 to 117 shown in FIG. 15. FIG. 70 shows an alternative drive arrangement to that shown in FIG. 15. In FIG. 70, the bulk of the drive arrangement is simply that shown in FIG. 15 and for convenience and brevity of discussion, similar features need not be described further.
As can be seen from FIG. 70, the biasing means 114, 115, 116 and 117 shown in FIG. 15 have been omitted. In this regard, the gas strut 612 may functionally replace those biasing means. Further, in the embodiment shown in FIG. 70, gearbox 650 has an input shaft 652 that can accept drive from a removable electric motor. Therefore, rather than having the electric motor mounted to the scaffolding unit (which may require that each platform be provided with an electric motor), a single electric motor that is connectable to the driveshaft and removable from the driveshaft 652 may be used to separately raise each platform. In another alternative embodiment, the driveshaft 652 may include or be replaced by a 90 degree gearbox which will allow the motor to be removed in a vertical direction
The drive arrangement shown in FIG. 70 also includes a T gearbox 654 that drives a ball screw 656 that extends through respective ball nuts 658, 660. The respective ends of the ball screw 656 are mounted for rotation with in transverse shafts 662, 664.
FIG. 71 shows a perspective view of the scaffold unit 600 in the extended position. The scaffold unit 600 includes four gas struts that are connected in vertically extend from the upper deck 606. Three of these are shown at 612, with the fourth one being in FIG. 71. A hand rail 670 can also be seen. Like other embodiments, the hand rail 670 is mounted to the pivot points between one of the scissor leg is. However, handrail 670 may remain connected to the legs during storage, as is shown in FIG. 73.
As shown in FIG. 72, the central part of the scissor linkage 673 shown in FIG. 71 includes a lower leg 674 that is pivotally connected by a pivot pin 676 to upper leg 678. The scissor linkage also includes an upper leg 680 that is pivotally connected to a lower leg 682. The pivotal connection is made by providing a pin 684 having an internal thread extending through respective openings in or near the ends of the legs 680, 682 (one of the openings is shown at 685). A locking washer 686 and a lock nut 687 are used to hold the pivot pin 684 in place. The locking washer 686 has an internal projection 688 that rest inside key way 689 of the pivot pin 684 to thereby fix the locking washer 686 in position relative to the pin 684.
The scaffold unit of the present invention provides a scaffold unit that is very compact when in the lowered position, thereby enabling easy transport and storage. The scaffold unit may be raised to its raised position to provide one or more raised support platforms to enable workers to work on higher levels of the building. Further scaffold units may be mounted on top of the scaffold unit if greater height is required. A number of units may be mounted next to each other so that scaffolding extending along a side of a building can be obtained. Erection of the scaffold unit beside a building is much quicker and less labour-intensive than erection of conventional scaffolding. In some embodiments, the scaffold unit has linkages at each corner of the support frames, thereby providing increased strength and stability.
In embodiments where the scaffold unit has scissor linkages at each corner and the scissor linkages extend at an angle of greater than 80° when in the erected position, when the unit is fully erected the scissor linkages provide minimal interference to access to the building or a worksite located adjacent to the work platform. In this regard, as the scissor linkages are located at the corners and are extending in any sensually vertical direction, the scissor linkages do not extend to any great lateral extent, thereby providing clear space along the bulk of the length of the work platform. Thus, the scissor linkages do not substantially get in the way. Further, if two or more scaffold units are placed end-to-end, a relatively unhindered walkway between adjacent units can be formed.
Significant other advantages also arise from the present invention, when compared to conventional scaffolding units. In particular, the present invention is likely to greatly reduce or even eliminate accidents and injuries due to manual handling, falling objects and fall from heights during erection and dismantling. The labour force required to install the scaffolding is greatly reduced when compared to conventional scaffolding. Indeed, it is envisaged that only 2 installers will be required to install and erect the scaffold unit of the present invention at a worksite. Erection of conventional scaffolding can often require a significantly larger workforce. The installation time required to install the scaffold unit to its working height is also greatly reduced, when compared to conventional scaffolding. It will be appreciated that the requirement for a smaller number of workers to erect the scaffold unit and a more rapid installation time means that the scaffold unit of the present invention can be installed at significantly reduced costs when compared to conventional scaffolding. A further advantage arises in that installation costs of scaffold units of the present invention can be quite accurately estimated, thereby providing more certainty in preparing cost estimates and reducing the time and costs associated with tendering for projects.
The scaffold unit of the present invention is provided essentially as a fully assembled product from the factory (with only a small or minimal number of removable or attachable elements). This reduces the number of loose components and also reduces or minimises the likelihood of components going missing. Further, the worksite can be much tidier and there is reduced or no need for storage of components on-site. This also reduces storage costs and transport costs when compared to conventional scaffolding. Further, smaller storage facilities may be used. As a further benefit, it is believed that the scaffold unit of the present invention should be able to be certified at the factory where it is assembled, thereby reducing certification costs on site.
In some embodiments, the scaffold unit of the present invention has a containment screen fixed to the scaffold unit. Therefore, as the scaffold unit is erected, the containment screen automatically extends and is in place without requiring additional installation. In some embodiments, the height of the work platforms can be closely and easily controlled.
In the present specification and claims (if any), the word ‘comprising’ and its derivatives including ‘comprises’ and ‘comprise’ include each of the stated integers but does not exclude the inclusion of one or more further integers.
Reference throughout this specification to ‘one embodiment’ or ‘an embodiment’ means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases ‘in one embodiment’ or ‘in an embodiment’ in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.
In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims (if any) appropriately interpreted by those skilled in the art.

Claims

1. A scaffold unit comprising at least two support platforms or two support frames, at least one of the support platforms or support frames being movable between a lowered position and a raised position, a plurality of scissor linkages linking one support platform or support frame with a next support platform or support frame, each of the scissor linkages including a plurality of legs, each scissor linkage having a leg pivotally connected to or near a corner of one of the support platforms or support frames and a leg pivotally connected to or near a corner of a next support platform support frame, wherein a leg is pivotally connected at or near each corner of a support platform or support frame.

2. A scaffold unit as claimed in claim 1 wherein the scissor linkages comprise a first leg and a second leg, with the first leg being pivotally connected to a lower support platform or support frame at or near a corner of the lower support platform or support frame, the first leg and second leg being pivotally connected to each other at an approximate midpoint thereof, the second leg having a lower end that is reciprocally movable relative to the lower support platform or support frame, the first leg having an upper end that is reciprocally movable relative to an upper support platform or support frame, the second leg having an upper end that is pivotally connected to the upper support platform or support frame at or near a corner of the upper support platform or support frame.

3. A scaffold unit as claimed in claim 1 wherein the scissor linkages comprise a first leg and a second leg, with the first leg being pivotally connected to a lower support platform or support frame at or near a corner of the lower support platform or support frame, the first leg and the second leg being pivotally connected to each other at an approximate midpoint thereof, the second leg having a lower end that is reciprocally movable relative to the lower support platform or support frame, a third leg having an upper end that is pivotally connected to an upper support platform or support frame at or near a corner of the upper support platform or support frame, a fourth leg having an upper end that is reciprocally movable relative to the upper support platform or support frame, the third leg and the fourth leg being pivotally connected to each other at an approximate midpoint thereof, the third leg having a lower end that is pivotally connected to an upper end of the first leg and the fourth leg having a lower end that is pivotally connected to an upper end of the second leg.

4. A scaffold unit as claimed in any one of the preceding claims wherein the pivotal connection points of the respective legs to one of the platforms or support frames are located outwardly of the sliding ends of the other legs of each scissor linkage.

5. A scaffold unit as claimed in any one of claims 1 to 3 wherein the sliding ends of the respective scissor linkages are located outwardly of the pivotal connection points of the other ends of each scissor linkage.

6. A scaffold unit as claimed in any one of the preceding claims wherein each support platform or support frame has 4 scissor linkages attached to a lower side thereof.

7. A scaffold unit as claimed in any one of the preceding claims further comprising a drive means for raising and lowering at least one of the support platforms or support frames between the lowered position and the raised position.

8. A scaffold unit as claimed in claim 7 wherein the drive means is mounted to the scaffold unit.

9. A scaffold unit as claimed in any one of the preceding claims wherein legs of the scissor linkages extend at an angle of less than 8° to horizontal when the scaffold unit is in the lowered position, or legs of the scissor linkages extend at an angle of from 3° to 7° to the horizontal when the scaffold unit is in the lowered position, or legs of the scissor linkages extend at an angle of from 4° to 6 to the horizontal, when the scaffold unit is in the lowered position. °, or legs of the scissor linkages extend at an angle of from about 4° to 5° to the horizontal when the scaffold unit is in the lowered position.

10. A scaffold unit as claimed in any one of the preceding claims wherein the scaffold unit further comprises a further drive means or a biasing means to facilitate initial movement of a support platform or support frame from a lowered position.

11. A scaffold unit as claimed in claim 10 wherein the further drive means is selected from one or more of a column lifter, a hydraulic ram, an air bag, or a pneumatic cylinder and the biasing means is selected from one or more springs, or one or more resilient members, or one or more elastomeric or rubber members, or one or more elastomeric or rubber blocks, or one or more struts, or one or more gas struts.

12. A scaffold unit as claimed in claim 10 or claim 11 wherein the biasing means provides a biasing force to the legs or to one of the support platforms or support frames when the scaffold unit is in the lowered position, the biasing force acting in a direction to assist raising the scaffold unit.

13. A scaffold unit as claimed in any one of claims 10 to 12 wherein the biasing means extend in a vertical direction.

14. A scaffold unit as claimed in any one of the preceding claims wherein the legs extend at an angle of greater than 80°, or greater than 85°, to the horizontal when the scaffold unit is in the raised position.

15. A scaffold unit as claimed in any one of the preceding claims wherein the legs extend at an angle of about 86.5° to the horizontal when in the raised position.

16. A scaffold unit as claimed in claim 2 or 3 or as claimed in any one of claims 4 to 15 when appended to claim 2 or claim 3 wherein the legs that are reciprocally movable relative to one of the support platforms or support frames are connected to one or more rollers that can move along a track or guide in or mounted to the support platform or support frame.

17. A scaffold unit as claimed in claim 7 or in any one of claims 8 to 16 when appended to claim 1 wherein the drive means comprises a drive motor or an electric motor.

18. A scaffold unit as claimed in claim 17 wherein the drive motor or the electric motor causes a drive bar or drive member to reciprocally move relative to one of the support platforms or support frames, movement of the drive bar or drive member causing the legs to move.

19. A scaffold unit as claimed in claim 17 or claim 18 wherein the drive bar or drive member causes at least some of the legs that are mounted for reciprocal movement relative to one of the support platforms or support frames to move relative to the support platform or support frame.

20. A scaffold unit as claimed in any one of claims 17 to 19 wherein the drive motor causes a ball screw or a worm gear to rotate, the ball screw or worm gear extending through a nut fixedly mounted to a drive bar or drive member, wherein rotation of the ball screw or worm gear causes the drive bar or drive member to move laterally outwardly or laterally inwardly.

21. A scaffold unit as claimed in claim 21 wherein the drive motor passes drive through a gear arrangement to cause rotation of the ball screw or worm gear.

22. A scaffold unit as claimed in any one of the preceding claims wherein the scaffold unit is also be provided with a braking means that can be selectively actuated to prevent raising or lowering of the scaffold unit and selectively turned off or disengaged to allow raising or lowering of the scaffold unit.

23. A scaffold unit as claimed in claim 22 wherein the braking means engages with one or more components of the drive means.

24. A scaffold unit as claimed in any one of the preceding claims wherein the scissor linkages may be moved and repositioned inwardly or outwardly relative to the support frame or support platform.

25. A scaffold unit as claimed in claim 24 wherein the support frame or support platform is provided with a plurality of spaced openings, one leg of a scissor linkage having an opening that can be brought into alignment with one of the plurality of spaced openings and a connecting pin passed through the aligned openings to thereby pivotally connect the one leg of the scissor linkage to the support platform or support frame, another leg of the scissor linkage that is associated with that support platform or support frame being movable along the support platform or support frame to allow repositioning of the scissor linkage.

26. A scaffold unit as claimed in any one of the preceding claims wherein at least one of the support platforms or support frames is provided with a support surface on which a worker can stand, the support surface including a horizontal extension movable between a retracted position and an extended position, the horizontal extension extending outwardly from the support platform or support frame when extended.

27. A scaffold unit as claimed in claim 26 wherein the horizontal extension extends along a length of the support platform or support frame.

28. A scaffold unit as claimed in any one of the preceding claims wherein the scaffold unit is provided with a protective screen on one side thereof.

29. A scaffold unit as claimed claim 28 wherein the protective screen automatically extends when the scaffold unit is raised.

30. A scaffold unit as claimed in any one of the preceding claims wherein the scaffold unit is provided with one or more handrails.

31. A scaffold unit as claimed in any one of the preceding claims wherein an uppermost support platform or support frame is provided with one or more handrails or guardrails that are removably mounted to a scaffold unit.

32. A scaffold unit as claimed in any one of the preceding claims wherein the support platform or support frame has a support surface that enables a worker to stand or walk thereon.

33. A scaffold unit as claimed in any one of the preceding claims wherein the scaffold unit is provided with one or more stays extending between one support platform or support frame and a next support platform or support frame.

34. A scaffold unit as claimed in claim 33 wherein the one or more stays extend diagonally between the support platforms or support frames.

35. A scaffold unit as claimed in claim 33 or claim 34 wherein the one or more stays are extendable stays.

36. A scaffold unit as claimed in claim 35 wherein the one or more stays include self locking means to lock the stays into an extended position when the scaffold unit is moved to the raised position.

37. A scaffold unit as claimed in any one of the preceding claims wherein the scaffold unit is provided with locking means for locking a first scaffold unit to a second scaffold unit positioned on top of the first scaffold unit.

38. A scaffold unit as claimed in claim 37 wherein the locking means comprises a locking bar extending through apertures located in the first scaffold unit and the second scaffold unit.

39. A scaffold unit as claimed in any one of the preceding claims further comprising a base unit, the base unit comprising a frame having one or more support surfaces on which the scaffold unit may be supported, the frame including a plurality of legs movable between a retracted position and an outward position, the plurality of legs comprising adjustable legs.

40. A scaffold unit as claimed in any one of claims 1 to 38 wherein the scaffold unit is provided with adjustable legs or adjustable feet that extend below the lower support platform or support frame in use.

41. A scaffold unit comprising at least two support platforms or two support frames, at least one of the support platforms or support frames being movable between a lowered position and a raised position, a plurality of scissor linkages linking one support platform or support frame with a next support platform or support frame, each of the scissor linkages including a plurality of legs, wherein the legs of the scissor linkages extend at an angle of at least 80° to horizontal when the scaffold unit is in the raised position. In some embodiments, the scaffold unit has at least 4 sets of scissor linkages linking one support platform or support frame for next support platform or support frame.

42. A scaffold unit comprising at least two support platforms or two support frames, at least one of the support platforms or support frames being movable between a lowered position and a raised position, a plurality of legs extending between one support platform or support frame and a next support platform or support frame, at least some of the legs having a pivotal connection to the support platform or support frame, the legs being movable during movement of the scaffold unit from the lowered position to the raised position and vice versa, the legs extending at an angle of less then 10° to horizontal when the scaffold unit is in the lowered position.

43. A scaffold unit comprising at least two support platforms or two support frames, at least one of the support platforms or support frames being movable between a lowered position and a raised position, a plurality of legs extending between one support platform or support frame and a next support platform or support frame, at least some of the legs having a pivotal connection to the support platform or support frame, the legs being movable during movement of the scaffold unit from the lowered position to the raised position and vice versa, wherein a position of the pivotal connection between a leg and the support platform or support frame can be moved between a plurality of positions.

44. A scaffold unit as claimed in any one of the preceding claims further comprising one or more of access stairs for providing allow access between support platforms or support frames on different levels, one or more rubbish chutes or one or more loading bays.

45. A scaffold unit as claimed in any one of the preceding claims further comprising a locking means to lock the scaffold unit in the lowered position.

46. A scaffold unit as claimed in any one of the preceding claims wherein substantially clear access to a work site is provided along a substantial length of the platform or support frame when the scaffold unit is in the extended configuration.