GB2180583A - An improved collapsible scaffolding - Google Patents

Abstract

The scaffolding consists of a platform 10 of generous size articulated on its back edge to an upright front frame 116 of the same width as the length of the platform. Breakable or releasable supports 60 hold the platform projecting forward from the front face of the frame, while the height of the platform above ground level is adjustable, either by moving the points of its articulation to the frame or by raising or lowering an upper section of the frame relative to the lower, or both. A bifurcated back stay 126 has the outer ends of its arms articulated to the frame and its lower, single, section adjustable for length and single relative to the frame. An extensible rigid brace 130 ties the back stay to the front frame near their bottom ends. Side and back guard rails 62, 66 above the level of the platform carry a curtain which closes the gaps between them and the corresponding edges of the platform to catch articles accidentally dropped or kicked while working. The whole assembly can be folded flat for carrying and storing. <IMAGE>

Description

SPECIFICATION An improved collapsible scaffolding This invention reiates to scaffolding which is collapsible as a unit to facilitate portability and enable it to be stored in the minimum of space when not in use. When jobs have to be done in the home or the garden on large expanses such as walls or hedges, the workman has little choice (other than the erection of elaborate and costly builders' scaffolding over the whole extent of, say, a wall) between a conventional ladder and a demountable tower which is composed of standard sections of builders' scaffold tubes. Two step ladders may be erected alongside the wall of hedge to support a plank between them, or other makeshift arrangements can be made from random materials which may be available.Conventional ladders have the disadvantage that the area of, say, wall surface accessible to a person standing on a rung is very restricted, necessitating frequent descents, repostioning of the ladder, and ascents. This procedure greatly increases the time required to do a job, and often limits the kind of tools or equipment which can be used. When two step-ladders and a plank are used, the time occupied in getting up and down to move the array is reduced but the risk of accident is increased by the unprotected nature of a plank and the possibility of warping of the plank or the unevenness of the ground on which the supporting ladders must stand. Furthermore, two step-ladders and a plank are cumbersome to transport and occupy a fair amount of storage space. They also impose a practical limitation on the effective height to which the working platform can be raised.

A tower has the advantage of providing a useful surface area of working platform which allows the placing of a variety of tools or equipment needed for the job conveniently to hand. This saves much time getting up and down to change tools and equipment as the job proceeds. Furthermore, it offers greater scope for the height to which the platform can be raised and, given a reasonably flat, hard floor or ground surface, stability can be improved. Guard rail protection can easily be provided for the safety of the worker. It is, however, a very cumbersome article and often presents considerable problems of assembly and adjustment of the level at which the platform is placed. It is also usually the kind of article in which the typical householder does not normally invest for personal retention, involving the problems of availability on hire when required.A tower also usually requires two people for its erection unless the user happens to be familiar with the handling of large heavy sections of scaffold tubing and their accessories.

It has been proposed to provide a structure for facilitating work on a wall which comprises essentially a catwalk supported at its ends on angle brackets one limb of each of which is adapted to rest against the wall while the other limb constitutes a support for planks or the like on which the workman stands while working. An inclined strut is pivotally coupled to each bracket at the internal angle thereof and rests on the ground at a distance from the base of the wall so as to form, with the ground and the wall, a triangulated support for each bracket without the need for fixing the brackets to the wall. Such a catwalk can only be used when there is a massive structure such as wall to withstand the horizontal reaction force exerted by each bracket thereon due to the inclination of strut.Furthermore, the catwalk must always lie close to the wall, and can never be free-standing, as may be required for hedge-trimming, tree-lopping, or other occupations in the absence of a massive structure. Furthermore, the erected catwalk depends entirely on the friction between brackets and the wall to stabilise it against sideways collapse, and the absolute firmness of the contact of each individual inclined strut with the ground to resist the horizontal outward force exerted on the strut at that strut due to the live load on the catwalk.

A construction of free-standing ladder with progressively more deeply indented rungs as their height above ground increases have been proposed, the stiles remaining vertical, and a forwardly inclined strut being hinged to the mid-point of the top rung so as to be positioned in front of the stiles to stabilise the structure. This construction only provides, from the point of view of the user, a conventional step ladder having only a single forward stay instead of the usual pair of stays hinged to the upper ends of the stiles and crossbraced to ensure their functioning as a unit.

Thus, the lateral stability of the ladder when erected is impaired, and its major utility is for the purpose of hedge trimming, where the single forward stay can be inserted into the hedge so as to bring the rungs close to the front of the hedge. The construction affords no more mobility to the user than a convention ladder, and the horizontal U-shape of each rung will also restrict freedom of lateral access to the hedge beyond the actual width of the ladder.

It is also well-known to provide the stiles of conventional ladders with telescopically adjustable feet or pads to correct for uneven or sloping ground so as to ensure that the ladder stands upright. Forward-projecting trays for carrying tools or other articles required while working up the ladder are commonplace fittings, but these do not constitute working platforms and are restricted in width to the width of the ladder.

It is an object of the present invention to provide-primarily (though not exclusively) for the convenience of the ordinary householder-a collapsible structure which is relatively easily portable and which embodies a working platform of considerably greater surface area than is normally available; is less reliant for stability on the availability of a hard level floor or ground surface; and can be assembled either as a lean-to or as a free-standing structure-the former being more appropriate where work is to be carried out on a wall while the latter is more convenient when a hedge is to be trimmed, a tree to be pruned, or fruit to be picked.

According to the present invention, a collapsible scaffolding consists of an assembly of articulated elements comprising a working platform of ample size for a person to move about and to carry a variety of tools or equipment for working on an expanse of wall or other standing structure (e.g. a hedge), and a rigid collapsible framework for supporting the platform at a chosen height above ground.

The collapsible framework comprises a front loading frame of a width when erected substantially equal to the length of the platform and at a level near the top of which the platform is articulated thereto so as to be capable of being cantilevered forwards from the frame.

A rear stay is also articulated to the frame at or near the same level and can be extended backwards from the frame to rest on the ground at a single point sufficiently far behind the frame to stabilise it in the erected position. An adjustable rigid strut links the stay to the frame at or near their respective bottom ends so as to complete a rigid triangulated system for giving stability to the frame irrespective of irregularities in the surface on which it stands.

Ideally, in order to increase the utility of the invention, especially outdoors, where high walls or hedges or trees may require attention, the front frame may be extensible by making it in upper and lower sections, the upper section being slidable on the lower section, and means being provided for supporting the upper section at a variety of heights above ground level. The platform is articulated to the upper section, and in such an extensible front frame arrangement, the rear stay may also be articulated at its upper end to the upper frame, and be made similarly extensible and lockable in the desired extended position.

Preferably, the back stay is bifurcated at a point intermediate its length and the two arms of the fork are articulated to the side uprights or stiles of the front frame.

Conveniently, the guard rails are collapsibly mounted on the side uprights or stiles at a suitable height above the level of the platform to protect a worker from falling backwards or sideways off the platform.

Advantageously, side and back panels are mounted so as to fill the gaps between the side and back guard rails and the corresponding edges of the platform to catch articles which may be dropped on the platform while working, or accidentally kicked while moving.

Such panels may, for example, be constituted by a fabric skirt attached to both the guard rails and the platform so as to fold when the structure is collapsed.

Where it is proposed to use electric power tools, especially if the extensjible form of the invention is used, it may be advantageous to clip or otherwise secure a length of cable, coiled as necessary to accommodate the extending action, to the back stay and to provide separable couplings at each end for connection of the supply at the foot of the back stay and of the tool at platform level, respectively. Such a provision relieves the worker on a high platform of the not inconsiderable drag of a long suspended catenary of cable from the handle of the tool to the ground.

Practical embodiments of the present invention will now be described by way of illustration only with reference to the accompanying drawings in which: Figure 1 is a purely schematic illustration of an erected portable scaffolding embodying the principle of a triangulated support for the front frame carrying the platform; Figure 2 is a schematic side view of the article of Fig. 1 in the collapsed state; Figure 3 is a perspective view of an extensible portable scaffolding generally similar to Fig. 1, but showing the optional extra stabilisers for use at higher platform levels; Figure 4 is a side elevation of the scaffolding of Fig. 3 but erected in an alternative attitude for trimming a hedge, and Figure 5 is a scrap view of a modified construction of the design shown in Fig. 3.

Referring first to Figs. 1 and 2, a simple form of portable and relatively easily errected and dismantled scaffolding consists essentially of a platform 10 articulated at its back edge to the side stiles 12, 14 of an upright loadbearing front frame 16. The side stiles 12, 14 are shown as being braced by transverse stretchers 18. The platform 10 is intended, when erected as shown in Fig. 1, to be cantilevered forward from a point near the top of the front frame 16. It is braced in the horizontal position by a pair of side struts 20 which are articulated to the front edge of the platform 10 and run backwards and downwards to the respective side stile 12, 14 where they are releasably pinned in any conventional manner (not shown). In an optional modified version of the article, the platform 10 may be articulated to the stiles 12, 14 at a choice of alternative heights. Fig. 1 also illustrates a further optional modification in the provision of legs 22 attachable to the front edge of the platform and adjustable for length at 24 to match the chosen height of the platform 10.

When the scaffold is to be used by a nervous person, these legs 22 serve to give confi dence. Ideally, they would be set into downwardly open fixed sockets on the underside of the platform to resist any tendency to splay under load on a slippery or smooth surface.

The front frame 16 is braced in the erected position by a back stay 26 articulated at its upper end on a stretcher 18 near the top of the front frame 16. This back stay 26 is laterally braced by a pair of divergent struts 28 which are fixed to the stay 26 at their lower ends and articulated at their upper ends to the same stretcher 18 as that to which the back stay itself is pivoted. A rigid brace 30 adjustably connects the back stay 26 to the front frame 16 at an intermediate height so as to lock the back stay 26 at the desired angle to the plane of the front frame 16 and thereby to form a triangulated steady assembly with 3-point support on the floor or ground which ensures stability of the platform 10 irrespective of any irregularities in the surface on which the scaffold is set up.

In use, the platform 10 is set at the required height for working. This may be achieved by either selecting one of a plurality of articulation points on the stiles 12, 14, or by extension of the stiles 12, 14 (as indicated at 12a, 14a) and the back stay 26, as indicated at 26a. The platform 10 is offered up against a wall to add further stability, and to prevent the scaffold from tipping forwards.

The struts 20 are locked in their platformsupporting positions; the back stay 26 is extended as required and locked, and the brace 30 is clamped to the back stay to render the triangular structure 12, 14, 26 rigid and stable. Access to the platform 10 is gained by a conventional step ladder or other device which forms no part of the present invention.

By virtue of the height at which the back stay 26 is articulated to the front frame 16, together with its extensibility, the assembled scaffold can span low walls or small flower beds so as to ensure an adequate base for stability. The platform 10 can be made any size to suit the user's requirement, but a typical length might be between 1.5 and 2 metres, and its width can be around 1 metre, which gives a person walking on a wall good space for moving around and keeping tools or items of equipment beside him or her on the platform.

Referring now to Fig. 3, a generally similar collapsible scaffold consists of a two-section frame 16, 116, the lower section 16 being of a height of about 10 ft.6 ins. (say, 3 metres), and the upper section perhaps slightly longer to aliow the platform 10 to be raised about twice as high above ground level as in the case of Fig. 1. The platform 10 may measure about 5 feet (say, 150 cm.) long by about 2 ft. 6 ins. (say, 75 cm.) wide. These dimensions are, of course, entirely optional, and can be varied at will to suit different sets of circumstances.

The upper section 116 of the frame slides over the lower section 16 under the control of a guide bracket 40 at the top end of each stile 12, 14 of the lower section and of a cranked sprag 42 on the lower part of each stile 112, 114 of the upper section. Each sprag 42 is selectively engageable, in known manner, with one of a series of lugs 44 spaced along the inward face of each stile 12, 14. The lower section stiles 12, 14 are crossbraced at 46 for rigidity and parallelism, and their tops preferably carry brackets 48 to which are universally pivoted the top ends of auxiliary steadies 50.Whilst these steadies are optional fittings, they perform two useful functions: a) they improve the lateral stability of the front frame 16, 116 when the scaffolding is in use, especially when the upper section 116 is extended to its full height, and b) they steady the lower section 16 when the upper section 116 is being adjusted for height. The provision of universal, or partial universal, articulation between the auxiliary steadies 50 and their respective brackets 48 allows the steadies to be placed in the most suitable positions having regard to the terrain on which the scaffolding is to be erected.

Each steady 50 is tied back to the adjacent stile 12, 14 by a tension element shown schematically in Fig. 3 and a chain which is permanently fixed at one end while the other end is secured (say, to the steady 50) by engaging the appropriate link with a hook on the steady.

Each steady is extensible by the provision of an adjustable foot section 52 which has a pivotal shoe or pad 54 on its bottom end to ensure its conformity with the local contour of the ground, and is adjustably joined to the main body of the steady by a conventional cotter pin 56 selectively engageable with a plurality of holes 58 in the foot section. The shoe 54 may be drilled to allow a ground spike to be driven therethrough into the ground in the desired position of adjustment of the steady 50. Similar shoes 54 are also mounted on the bottom end of each stile 12, 14.

The upper section 116 of the front frame carries the platform 10 which is pivotally carried at its back edge by pivots (not shown) in the upper stiles 112, 114. It is supported by extensible struts 60 which connect the front edge of the platform 10 to a point on the respective stile 112 or 114 below the pivot for the platform. The feature of extensibility of the struts 60 is necessary to enable the front frame 16, 116 to be tilted backwards when the scaffolding is free-standing (as shown in Fig. 4) while still allowing the platform 10 to be set horizontal. Although the main adjustment for height of the platform 10 is achieved by adjusting the upper frame section 116 on the lower 16, it may be advantageous to provide alternative positions of the pivotal attach ment of the back edge of the platform 10 to the stiles 112, 114.

Above the level, or the highest level, of attachment of the platform 10 to each stile 112, 114, a respective side fence or guard rail 62 is hinged thereto so as to be collapsible when the scaffolding is struck. In Fig. 3, this hinge connection is arranged so that the fences or rails 62 fold down against their respective stiles, and are braced in their respective erected positions by hinged struts 64.

These struts are also adjustable for length as in the case of the platform struts 60. The fences or rails 62 are shown in the drawing as interconnected by a pair of transverse parallel rails 66 which are rigidly connected at their ends bracket 68 integral with the respective fence or guard rail 62. Partly this arrangement is a safety precaution to ensure that both guard rails are erected at the same time, and partly the interconnecting parallel rails 66 form a rear fence. A safety curtain (or solid panels) can be fitted to close the gap between the side and back edges of the platform 10 and the side and back fences, respectively, to catch tools or items of equipment which may be accidentally kicked while working.

Above the side fences 62, the upper section 116 is provided with rearward lugs 70 to which are articulated the upper ends of the arms 128 of the bifurcated back stay 126. As in Fig. 1, this stay is extensible, and a rigid brace 130 interconnects the back stay 126 and the lower frame section 16, the brace being adjustable for length to accommodate the height adjustments of the upper frame section 116. The bottom end of the back stay carries a pivotally attached plate 72 for giving a firmer base when placed on soft ground.

The plate can be pierced to take a ground spike for greater security.

The procedure for erection and collapse of the structure of Fig. 3 is basically the same as for that of Fig. 1, allowing for the extra complication of the extensibiiity of the front frame 16, 116, and the additional steadies 50 when used. When collapsed as shown in Fig. 2, the scaffoldings of Figs. 1 and 3 retain their full width. If the arrangement of cross-bracing 46 in Fig. 3 is substituted for the stretchers 18 in Fig. 1, it would be possible, by some simple modifications, to enable the stiles 12, 14 to be collapsed towards each other.In order to do this, however, the platform 10 must be made detachable from the stiles 12, 14; the divergent struts 28 must be releasable from their connection to the lower part of the back stay 26, and the cross-braces 46 must be pinned to the stiles 12, 14 at both ends and where the braces cross over at their mid points. Then, by detaching the platform 10; removing the pin at the cross-over point of the braces 46, and releasing either their bottom or their top connections to the stiles 12, 14, the latter can be collapsed against each other to reduce the space required for storing the assembly of Fig. 1.

Having regard to the fact that nowadays there is an increasing range of power tools available to potential users of collapsible scaffoldings according to the present invention, and to the fact that, especially when using the design of Fig. 3 at maximum extension of the upper front frame section 116, the weight of flex hanging from a power tool to ground level seriously curtails the ease of use of the tool,it is envisaged that an electric power socket outlet can be mounted at a convenient point on the structure, on or close to the platform, and that power feed cable thereto be clipped at intervals to a stile or the back stay 126.

From the safety point of view, it is highly desirable that the clips holding the cable to the stile or the back stay should be easily detached in the event that a passer-by were to trip over the trailing cables. Alternatively, the length of cable clipped to the stile or the back stay could be made a permanent feature of the design and be anchored at its bottom end by one half of a readily separable connector, the other half of which is connected to the supply cable leading from the power source.

Fig. 4 illustrates the scaffolding of Fig. 3 erected as a free-standing unit for trimming a high hedge H, the front frame 16, 116 being tilted back at least far enough to ensure that the front edge of the platform 10 does not project forward of the vertical plane through the points where the stiles 12, 14 rest on the ground. In this attitude, the scaffolding is stable and the platform 10 can be positioned close to the hedge H.

Fig. 5 illustrates some possible modifications of the design of Fig. 3. In the first place, the stiles 112, 114 of the upper front frame section 116 are telescopically mounted inside the tubular stiles 12, 14 of the lower section.

Secondly, the platform 10 (shown in dotted lines so as not to obscure the telescopic junction of the stiles 12, 112) is supported in its working position by a pair of hangers 74 suspended from suitably reinforced side rails 62.

The latter are shown hinged on a vertical axis to a top rail 66 which also serves as a rear guard rail and as a stiffener for the upper ends of the upper frame stiles 112, 114. The reinforcement shown in Fig. 5 for the side rails 62 consists of a vertical plate 76 secured to the guard rail 62 and having its rear vertical edge hinged at 78 to the adjacent stile 112 or 114 about the same vertical axis as that of the guard rail hinge, the side guard rails 62 being swung inwards when the scaffolding is collapsed.The bottom end of each hanger 74 is shown hooked at 80 to engage either be neath the side edge of the platform 10 or, preferably, in a hole in a side flange of the platform 10, To avoid accidental disengage ment of a hook 80, its extremity is preferably up-turned to form a positive lock so long as the scaffolding is erected, and especially when there is a load on the platform 10. If preferred, the hooks 80 may be positively but releasably secured in their working positions for added security. Alternatively, the guard rails 62 and reinforcing plates 76 may be made as single integral components and may form also the side panels of the safety curtain for protection against accidentai dislodgement of tools or items of equipment from the platform 10.

When a collapsible scaffolding according to the present invention is used for external building construction, repairs or maintenance, its free-standing three-point support facilitysupplemented if required by the auxiliary steadies 50 (Fig. 3)-renders it particularly useful for easy access to overhanging parts such as gutters and soffit boards at the eaves. Also, when access is required to such items as dormer windows, the platform 10 may be of nested or telescopic construction in that one or more plates of generally similar size to the main component 10 of the working surface which is articulated to the front frame 116 may overlie it, or be nested beneath it, so as to be slidable forwards after the main component 10 has been located above gutter level and to rest on the roof in front of the dormer window.

The materials to be used in the construction of scaffolding according to the invention are optional, but after safety the main consideration will be lightness, and ease of handling.

Wherever possible, sharp edges, corners, etc.

will be avoided to reduce the risk of injury during handling. Provision may be made for linking each scaffolding to a similar neighbour to form a longer stretch of platform 10.

Claims (8)

1. A collapsible scaffolding comprising a substantially flat load-bearing frame adapted to be mounted upright and substantially parallel to a standing structure such as a wall or hedge on which work is to be done; a flat work platform of a substantial length and width to enable workman to move easily thereover and to deposit tools or items of equipment with the aid of which to carry out the required work, the platform being articulated at its back edge to the load-bearing frame near its upper end so as to be adjustable from a collapsed position overlying the frame to a working position in which it is cantilevered forward from the plane of the frame; and a rear stay hinged at its top to the frame at or near the upper end thereof and adjustably clamped to the frame near their respective bottom ends so as to support the frame in its erected condition.

2. A scaffolding according to claim 1 wherein the load-bearing frame is composed of upper and lower sections slidably coupled together in such a way that the upper section can be selectively extended to a range of heights relative to the lower section and secured thereto when so extended, the working platform being articulated to the upper section.

3. A scaffolding according to claim 2 wherein the back stay is correspondingly extensible, and means is provided for locking together the relatively extensible sections.

4. A scaffolding according to any preceding claim wherein the back stay is bifurcated intermediate its ends, the two arms of the fork being directly pivotally attached to the load-bearing frame at laterally spaced points.

5. A scaffolding according to any of claims 1-4 wherein one or more auxiliary extensible steadies are universally, or partially universally, articulated to the front frame so as to be capable of being located in contact with the ground within a range of positions to the side or back of the front frame.

6. A scaffolding according to any preceding claim wherein guard rails are collapsibly mounted on the side members of the loadbearing frame at a suitable height above the level of the platform to protect a workman from falling off either end of the platform and off the back edge thereof.

7. A scaffolding according to claim 6 wherein side and back panels are collapsibly secured to the guard rails or the side and back edges of the platform, or both to guard against the risk of tools or equipment being accidentally pushed from the platform during use of the scaffolding.

8. A scaffolding substantially as hereinbefore described with reference to Figs. 1 and 2; Fig. 3; Fig. 4 or Fig. 5 of the accompanying drawings.