Background Art In the construction industry, and in a wide variety of other trades, platforms in the form of planks are held by scaffolding to provide a support surface for people, tools and building materials etc. Each plank is in the form of an elongate platform with a generally flat supporting surface.

Such platforms are provided in standard sizes, and when a span is required which is greater than that offered by the platform, extra framework must be erected and further platforms or planks positioned adjacent to the existing platforms.

Summary of the Invention In a first aspect, the present invention provides an expandable platform for use with scaffolding, including a first platform section slidably mounted to a second platform section, the first section being movable between a retracted position in which it is retracted and an extended position in which it extends out from the second platform section to form an expanded platform, the expandable platform further including a locking means for locking the first and second platform sections against relative sliding, wherein the locking means includes an engagement surface on one of the platform sections and a contact portion on the other of the platform sections arranged to

abut the engagement surface such that relative sliding is prevented.

In this way, a platform of a standard size can be provided, but when necessary it can be extended to span a longer distance between wider spaced supports and locked in the extended position to provide stability. The locking means may be operable to prevent sliding at one or more positions between and including the retracted and extended positions.

The prior art does not include an expandable platform with such a locking mechanism. It is known to lock two planks together side-by-side by passing a pin through holes in both planks. However, such a locking mechanism does not provide a rigid connection between planks as the holes are slightly larger than the pin.

Preferably, the first platform section is nested within the second platform section in the retracted position. In this way, the platform can function like any other standard length platform, and then can be extended when required.

The first and second platform sections may each be in the form of planks.

The locking means may further include a force transmitting means for forcing the contact portion to abut against the engagement surface. The force transmitting means may include a threaded shaft and a threaded bore in one of the platform sections, the threaded shaft being arranged to be tightened against the engagement surface, wherein the contact portion is formed on an end surface of the threaded shaft.

The force transmitting means may alternatively include an elastically resilient arm mounted on one of the platform sections, the arm being biased to force the contact portion to abut against the engagement surface.

The engagement surface may include profiled surface features for assisting engagement with the contact portion.

The contact portion may be shaped to complement and engage the surface features. The surface features may include a repeating profile having a series of troughs for receiving the contact portion. In one embodiment, the repeating profile is similar to a sine curve. A wide variety of other repeating profile shapes may be used instead, such as a saw tooth profile, a square wave profile, or a series of slots. In another embodiment, the arm and engagement surface are arranged to operate as a ratchet mechanism.

The force transmitting means may alternatively include an eccentrically-mounted cam or disk portion mounted for rotation on one of the platforms such that it can be rotated to force the contact portion to abut against the engagement surface. The engagement surface may include a repeating profile with troughs shaped to receive the contact portion. The repeating profile improves the engagement between the contact portion and the engagement surface, and thereby improves the locking action. In another embodiment, the contact portion includes a series of regularly-spaced teeth for engagement with corresponding teeth on the engagement surface.

The engagement surface may be elastically deformable.

In use, the contact portion may create a depression where it abuts the deformable engagement surface, thereby improving the locking action. The contact portion may additionally include a series of small projections such as teeth for enhancing locking against the deformable engagement surface.

Preferably, the platform further includes a coupling means operable at a joining region of the first and second platform sections to restrain lateral movement but provide for guided longitudinal movement of one section relative to the other. In other words, the coupling means ensures that the platform remains as an integral element in all positions between and including the extended then retracted positions.

Preferably, the coupling means includes: -a pair of opposing outer flanges respectively extending down from and along opposing sides of the second platform section; and -a pair of opposing inner flanges extending down from and along opposing sides of the first platform section; wherein the inner flanges nest and are slidable within at least part of the outer flanges respectively in a manner that restrains said lateral movement. In this way, the coupling between the first and the second platform sections can be located under the platform in use, thus not interfering with a user thereof.

In a first embodiment of the coupling means, a lower edge of each outer flange curves inwardly and upwardly towards an underside of the second platform section to define a hooked region along each edge, and the inner flanges each include a corresponding curved lip extending along a lower edge thereof which nests within the hooked region in positions between and including the retracted and extended positions.

In an alternative embodiment of the coupling means, each outer flange is defined by at least one box section extending along a respective side of the second platform section, with an inwardly facing longitudinal slot being defined in an opening to a hollow interior of each box section, and each inner flange includes at least one projection that extends through a respective slot to latch the inner flange to its respective outer flange.

In either of these arrangements of the coupling means, advantageously the first platform section may be slidably moved with respect to the second platform section in situ (i. e. in use), as it is the underside of the outer flanges that typically rests on the supporting frame work for the platform.

The projection can be defined by one or more ridges, t-shaped tongues, hooks or lugs extending along and projecting laterally out from a respective inner flange.

Preferably, the first and second platform sections combine to define a continuous plank in all positions between and including the retracted and extended positions.

In this regard, typically the upper surface of each platform section is continuous. Preferably, an arbitrary number of the extendable platforms can be connected together end to end by alternating the first and second platform sections.

A second aspect of the invention provides an expandable platform for use with scaffolding, including a first platform section mounted for pivotal rotation about a pivot axis, and a second platform section, the first section being rotatable between an extended position in which it extends out from the second platform section to form an expanded platform, and a retracted position.

Preferably, the plane of the first platform section slides parallel to the plane of the second platform section during pivotal rotation about the platform axis. The second platform section may also be mounted for pivotal rotation about the pivot axis. The second aspect of the invention has the advantage that it can be used for joining planks which connect at angles other than 180°, such as at a corner of a building.

The first and second platform sections may be retracted within a third platform section which is not rotatable about the pivot axis. For example, the third platform section may be a plank, and the pivot axis may be located at the corner of the plank. When the first and second platform sections are not needed they can be retracted within an end of the third platform section. In use, the third platform section could be placed along the edge of a building with the pivot axis positioned adjacent a corner, and the first and second platform sections could

be extended from within the third platform section to bridge the corner and connect with a fourth fixed platform section.

The first and second platform sections may be sector- shaped such that they resemble an open fan when in the extended position.

Preferably, an arbitrary number of alternating first and second platform sections can be connected together side by side such that they each pivot around the same axis.

Brief Description of the Drawings Notwithstanding any other forms which may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Fig. 1 shows a perspective view of a first expandable platform with a locking means in accordance with an embodiment of the present invention; Fig. 2 shows an end view of the platform of Fig. 1; Fig. 3 shows an end view of an alternative expandable platform in accordance with the present invention; Figs 4, 5 and 6 show partial cross-sectional end views of further alternative platforms in accordance with the present invention; Fig. 7 shows a perspective view of yet another expandable platform in accordance with the present invention; Figure 8 shows a partial view of an expandable platform with a first embodiment of a locking means; Figure 9 shows a partial side view of the embodiment shown in Figure 8; Figure 10 shows a pictorial view of a portion of the outer platform shown in Figure 8; Figure 11 shows an expandable platform incorporating a second embodiment of a locking means;

Figure 12 is a partial cross-sectional view of the locking means shown in Figure 11 as seen through section II -II; Figure 13 is an expandable platform incorporating a third embodiment of a locking means; Figure 14 is a cross-sectional view of the locking means shown in Figure 13 as seen through section III-III; Figure 15 shows a partial cross-sectional view of an alternative embodiment of a cam which could be used in conjunction with the expandable platform shown in Figure 13; Figure 16 shows an expandable platform with a third embodiment of a locking means; Figure 17 shows a plurality of extendable platforms connected end to end; Figure 18 shows an embodiment of an extendable platform configured as a guide rail; Figure 19 is an embodiment of an angularly expandable platform in an expanded configuration; Figure 20 shows the angularly expandable platform shown in Figure 18 when in the retracted configuration ; Figure 21 illustrates two angularly expandable platforms connected between planks adjacent a building; and Figure 22 shows an alternative embodiment in which a linear platform is connected to an angularly expandable platform section as seen in (a) the retracted position and (b) the expanded position.

Modes for carrying out the invention Embodiments of the first aspect of the present invention will now be described primarily with reference to its use in relation to expandable/retractable planks, but it should be appreciated that the principles of the invention can be applied to any platform for use with scaffolding.

Referring to Figs 1 and 2, an expandable platform is shown in the form of extendable plank 10. The plank includes an inner plank section 12 which is slidably mounted to and nestable within an outer plank section 14.

A locking means 15 mounted on the outer plank section 14 can be used for locking the two plank sections against relative sliding. Various embodiments of the locking means will be described in more detail later.

The outer plank section includes a generally flat supporting surface 16, with a pair of outer flanges 18 extending downwardly therefrom. Each outer flange curves inwardly and upwardly at its lower edge to define a hooked region 20 that extends along the length of the outer plank section.

Similarly, the inner plank section includes an upper supporting surface 22 with a pair of inner flanges 24 extending down therefrom and curving inwardly and upwardly along their lower edges. However, the inner flanges are sized such that they nest within the respective hook regions 20 (as best shown in Fig. 2) in a close facing but sliding relationship.

At the end of each inner flange 24, a longitudinal lip 26 is provided, which extends over the edge of a respective outer flange 18 (as best shown in Fig. 2). This lip facilitates sliding (e. g. the inner plank section can be supported just along the underside of each lip during sliding). Thus, a low friction surface can be provided between the lip and the edge of flange 18, or a roller bearing surface etc. can be provided thereat.

The inner plank section 12 is typically slid with respect to the outer plank section 14 between a nested or enclosed position in which section 12 is housed within section 14, and an extended position in which section 12 substantially protrudes out from section 14. The sliding is indicated by arrows A.

Typically, the components of the plank are formed from metal such as steel, aluminium or various alloys, (especially light weight metals). Alternatively, the components of the plank can be formed from high impact plastics material.

Fig. 3 shows an alternative embodiment to that shown in Fig. 2, where like reference numerals are used to denote similar or like parts.

In the embodiment of Fig. 3, the outer flanges 18 of the outer plank section are not integral with the upper supporting surface 22, but are joined to a plate 28 which is in turn connected to the underside of upper supporting surface 22 (e. g. via welding, screwing, bolting, adhesive etc.).

In addition, the free ends of each outer flange are bent over to define lips 30. Inner flanges 24 are each deformed to define a longitudinally extending recess 32 into which the lip 30 is received as shown. Thus, in this case the inner plank section can be supported at the upper inner face of each recess 32 on lip 30 for sliding movement therealong.

As can also be seen, the upper supporting surface 22 of inner plank section 12 overhangs inner flanges 24, thus providing a plank in the extended position of virtually constant width right along its length.

Also, the lower end of each inner flange 24 projects upwardly as a ridge 34 to facilitate a close facing (close nesting) arrangement of the lower part of each inner flange within its respective outer flange. In all other respects, the plank of Fig. 3 operates similarly to the plank of Fig.

1.

Referring to Figs 4, 5 and 6, differing inner and outer flange arrangements will now be described.

In Fig. 4, the inner flange 24 includes a T-shaped projection 36 extending laterally outward therefrom, the stem 38 of which extends through a slot 40, slot 40 in turn

opens into a hollow recess 42 (in which projection 36 is received), being part of box section 44. Box section 44 is in turn mounted to the underside of supporting surface 16 via connecting flange 46. The sliding operation of the plank of Fig. 4 is in all other respects similar to that of Figs 1 and 3.

Referring now to Fig. 5, the inner flange 24 can be provided with a lug 48 extending outwardly therefrom, and which is received in recess 50 of outer flange 18. Again, the outer flange 18 is mounted to the underside of the upper supporting surface 16. The operation of a plank of Fig. 5 is in all other respects similar to Figs 1 and 3.

Referring now to Fig. 6, an arrangement similar to that shown in Fig. 4 is depicted. However, in this case a differently shaped outer flange 18 is provided, and the upper supporting surface 22 of plank section 14 is in a close facing relationship within slot 52 to provide an additional sliding surface. The operation of the plank of Fig. 6 is in all other respects similar to that of the planks of Figs 1 and 3.

Referring now to Fig. 7, where like reference numerals are used to denote similar or like parts, the lower edges of outer flanges 18 are hooked around in a manner similar to that shown in Fig. 3. However, the inner flange is shaped in a form of a solid hook 54, the outline of which is shown in Fig. 7.

Again, the inner plank section can be slid between an extended position (typically wherein a short end portion of the plank is nested within the outer section) and a retracted position (wherein the inner plank section is completely nested (retained) within the outer plank section).

Typically, any of the bearing surfaces are formed from hard wearing materials, including toughened steels, steel alloys, etc., or ultra tough plastics material (which can

have the added advantage of providing low frictional resistance).

Whilst inner and outer flange arrangements have been defined which extend for the length of each inner and outer plank section respectively, a discreet series of inner and/or outer flange portions can be provided along the side lengths of each plank section, to achieve similar supporting effects. For example, a plurality of inner discreet flange portions can be aligned along both sides of the inner plank section, and these can be received within continuous outer flanges, extending along both sides of the outer plank section (or vice-versa).

Usually, the extendable plank is used in scaffolding, and is typically mounted to extend between a pair of supports. In this regard, the external surfaces of the inner and outer planks can be provided with appropriate integral couplings for attaching to the scaffolding supports. Alternatively, the planks can be lashed or otherwise fastened to the scaffolding (as is known). The plank can also be used in a wide variety of other applications, including by various trades people, and wherever planks, platforms or the like are required. Also, the plank can be easily widened to function as a platform.

Various embodiments of the locking means will now be described, each of which can be incorporated into any one of the expandable platforms shown in Figures 1-7. Figures 8 to 10 show a first embodiment of a locking means 60 for locking an inner plank 62 and an outer plank 64 against relative sliding. A portion of the outer plank 64 is shown on its own in Figure 10. The locking means 60 essentially consists of two parts: an engagement surface in the form of a profiled strip 66 on the inner plank section 62, having a series of regularly-spaced slots 68; and a contact portion in the form of a protruding ridge portion 76 mounted on the outer platform section 64 via a force transmitting means 70. In this embodiment, the force transmitting means is in

the form of a resiliently biased arm 70 which biases the ridge portion 70 to engage the slots 68. The strip 66 is mounted on the inner plank 62 parallel to the length thereof. In Figures 8 to 10, the strip 66 is mounted on an underside 72 of a hooked region 74 of the inner plank 62, and the arm 70 is mounted on the outer plank 64 such that it is resiliently biased to be parallel to the strip 66.

It can be seen in Figures 9 and 10 that the ridge portion 76 engages the strip 66 by protruding through an opening 77 in the outer plank 64 into one of the slots 78. The ridge portion 76 has an approximately semi-circular profile and complements the profile of each slot 78. Figure 9 shows the progressive movement of the arm 70 and ridge portion 76 along direction B from an unlocked position to a locked position. The inner plank 62 and outer plank 64 are both symmetric along their length, so an identical locking means 60 is provided under the hooked region 74 on each side. It will be understood that a variety of alternative profiles may be formed in the strip and on the arm, and that the strip may be located at various positions on the inner plank such as the upper supporting surface 22 or inner flange 18. In the embodiment shown, the strip 66 extends along the entire length of the inner plank 62. In an alternative embodiment, the strip is only provided along part of the length of the inner plank. For example, the strip could be provided close to one end of the inner plank such that the two planks are only locked against relative sliding when the inner plank is fully extended. There could also be a plurality of short strips formed at intervals along the length of the inner plank (for applications in which the plank extension does not need to be precisely adjusted).

A second embodiment of an extendable plank 80 with a locking means 82 is shown in Figures 11 and 12. Identical reference numerals have been used where the features are the same as those shown in Figures 8 to 10. In this

embodiment, the locking means 82 includes an engagement surface in the form of a toothed strip 84 on the upper supporting surface 22 of the inner plank 62, a force transmitting means in the form of a half gear wheel 88 eccentrically mounted on a pin 89 in the upper platform 16 of the outer plank 64, and a contact portion in the form of teeth 96 on the gear wheel 88. The gear wheel 88 protrudes through a slot 92 in the upper platform 16 and can be rotated through an angle of approximately 90° by means of a lever 94 formed on the gear wheel 88. The eccentric mounting of the gear wheel 88 is such that the teeth 96 of the gear wheel engage teeth 98 of the strip 84 when the lever 94 is oriented flush with the upper platform 16 of the outer plank 64, as shown in Figures 11 and 12. This is the locked position of the locking means 82. The teeth 96 of the gear 88 become disengaged from the teeth 98 of the strip 84 when the lever 94 is moved into an upright position with respect to the upper platform 16, placing the locking means 82 in an unlocked position. It is understood that two or more locking means could be provided on an extendable plank to distribute the load. The additional locking means could be provided in the upper platforms 22, 16 of the inner 62 and outer planks 64. Alternatively, locking means could be provided on the underside of both hooked regions 74 of the planks. The gear wheel 88 and strip 84 may be formed from any lightweight, durable and rigid material, such as metal, metal alloy, or plastics.

The toothed strip 84 could be integrally formed with the inner plank 62, or it could be fabricated separately and fastened into a channel 100 formed in the upper supporting surface 22 of the inner plank 62.

A third embodiment of an extendable plank with a locking means 102 is shown in Figures 13 and 14. The same reference numerals are used where the features are the same as shown in Figures 8 to 12. A half-disk 104 is eccentrically mounted on a pin 89 in a slot 92 in the upper

supporting surface 16 of the outer plank 64, and the upper supporting surface 22 of the inner plank 62 includes a strip 108 aligned with the cam 104. The strip 108 in this case is substantially smooth and elastically deformable.

Figure 13 shows the locking means 102 in a locked position in which the lever 94 mounted on the cam is flush with the upper supporting surface 16 of the outer plank 64. In this position, the contact portion (i. e. the outer surface 112 of the cam 104) engages the strip 108 by depressing a portion 114 of the strip 108. By moving the lever 94 into a substantially upright position, the cam is rotated and the outer surface 112 of the cam 104 disengages from the strip 108. The strip 108 may be formed from a known durable polymer, such as neoprene, and is bonded into a channel 100 in the upper supporting surface 22 of the inner plank 62. The contact portion can include a series of small projections 116 such as teeth in the outer surface 112, as shown in Figure 15, to enhance the engagement between the cam and the strip.

Figure 16 shows an extendable plank with an alternative form of locking means 118. In this embodiment, the engagement surface is the surface of the inner flange 24 of the inner plank 64. The contact portion is formed at an end of a force transmitting means in the form of a threaded shaft 120 which screws through a threaded bore 122 in the outer flange 18 of the outer plank 64 and abuts the inner flange 24 of the inner plank 62. The force transmitting means also includes a handle 124 at the end of the threaded shaft 120 to enable tightening and loosening of the locking means by hand.

Figure 17 shows a plurality of extendable planks 126, 128,130 joined end to end to form a single continuous plank. The ends 132 of each inner plank 62 reside within the end 134 of an outer plank 64. The plurality of extendable planks are locked together with a locking means 136 provided at each end of each outer plank 64.

Figure 18 shows an embodiment of an extendable plank which is designed to be supported by one of the outer flanges 18 of the outer plank 64. Such an embodiment could be used to provide an extendable hand rail, such as a safety rail on scaffolding. Projections 144 formed on the lower outer flange 140 of the outer plank 64 can be received in corresponding slots 146 of another platform 148 and held in place by placing a pin through each projection 144 on the opposite side of the platform 148.

Embodiments of an angularly expandable platform 150, 152 will now be described with reference to Figures 19 to 21. These platforms extend in an angular direction as indicated by arrows C, rather than in a linear direction.

The embodiment 150 shown in Figures 19 and 20 includes one sector-shaped inner platform section 154 and two sector- shaped outer platform sections 156. Each of the platform sections are connected by a separate hub 158 to a common axle 160, enabling the three platform sections 54, 56 to pivot independently around the axle 160. As shown in Figure 21, the angularly expandable platform 152 can be used to form a corner section between the ends of linear planks 162. The angularly extendable platform can be adjusted to conform to the angle at which two planks meet.

The example shown in Figure 21 illustrates scaffolding in which three sets of planks 162 are positioned parallel to three sides of a building 164, and two sets of angularly extendable platforms 152 bridge the gaps at the two 90° corners of the building. As shown in Figures 19 and 20, the inner platform section 154 has an identical profile to the outer platform section 156 but is sized such that it nests within a hooked region 166 at the outer edges of the outer platform section 156. Figure 19 shows the platform in an extended position, and Figure 20 shows the platform section in a retracted section. The platform sections 154, 156 can be locked in the extended position by aligning holes 168 in the inner 54 and outer 56 platform sections

and inserting a pin into the aligned holes. Each angularly extendable platform may include an arbitrary number of alternating inner and outer platform sections to span the required angular range. In the example shown in Figure 21, each angularly expandable platform 152 includes two outer platform sections 170 and two inner platform sections 172.

The angular span of each platform is preferably in the range from 1° to 90°, depending on the requirements. For example, the extendable platforms 152 in Figure 21 could also have been made with fewer platform sections (eg two sections) with a larger angular span, or alternatively more platform sections (eg six sections) of a smaller angular span. Each platform may include platform sections of different angular spans. For example, a platform may include four sector-shaped outer platform sections having an angular span of 20° and three sector-shaped inner platform sections having an angular span of 15°. At least one of the platform sections may be provided with brackets 173 for attachment to planks.

In an alternative embodiment shown in Figure 22, a single angularly-adjustable platform section 174 is combined with a linear plank 176. A hub 178 of the angular platform section rotates on an axle 180 which passes through a corner 182 of the plank. The angular platform section 74 can be used to bridge the gap between two planks meeting at any angle in the range between 0°and 90°.

Whilst the invention has been described with reference to a number of preferred embodiments, it should be appreciated that the invention can be embodied in many other forms.