Scaffolding including guardrails and platforms for safe assembly

Abstract

The invention relates to a scaffolding comprising - a first ladder (10) and a second ladder (10) each having two uprights (11) connected by rungs (12), - two guardrails (20), each guardrail comprising a frame (21) and four fixed plates (22) secured to the frame, each plate being capable of covering and cooperating with a rung of the first ladder or a rung of the second ladder to attach said guardrail to the ladders, - a platform (30) comprising at a first lateral end hooks in the form of grapples (36), said grapple hooks being configured to guide a substantially horizontal movement of bringing the platform into contact with support elements (25a) of the guardrails positioned in the vicinity of the second ladder and configured to horizontally cover an anchoring rung (12a) of the first ladder. Figure 1

Description

Title of the invention: Scaffolding comprising guardrails and platforms for safe assembly Technical field of the invention

[0001] The technical field of the invention relates to the field of scaffolding, and more precisely to the field of scaffolding equipped with guardrails and platforms for safe assembly, i.e. designed to be able to safely assemble or disassemble a platform level from the ground or from a previously constructed platform level. State of the art

[0002] A scaffolding conventionally comprises at least one pair of ladders each having two uprights connected by rungs, at least one platform and a pair of guardrails intended to be mounted above the platform to prevent a fall of an operator moving on the platform. In addition, ladders, guardrails and platform are configured to require the guardrails to be mounted before the platform is mounted in order to prevent a fall during assembly of the scaffolding, and conversely to require the platform to be removed before the guardrails are removed during dismantling.

[0003] For example, document DI = FR3011262 describes a scaffolding where the guardrails are put in place from a lower level and where the dimensions of the platform are chosen so that the platform is fixed to a false bar itself fixed to the guardrails. The installation of the platform is thus impossible without the prior installation of the guardrails. It follows that an operator cannot climb onto a platform without having first mounted the guardrails. The solution proposed by DI, however, requires the production of a false bar with its fixing elements on a ladder, which complicates the scaffolding and increases its assembly time.

[0004] Document D2 = FR297605 describes an alternative solution in which the scaffolding is provided with fixing means comprising, at at least one of the lateral ends of the platform, first support elements capable of cooperating with first guide elements carried by the guardrails to form a pivot connection making it possible to bring, by pivoting the platform, the other lateral end of the platform carrying second support elements to the height of a bar. The scaffolding described in D2 does not include intermediate elements for fixing the platform to the guardrails, such as the false bars used in DI. However, for the scaffolding of D2, the installation of a platform involves attaching one end of the platform to the guardrails and then pivoting the platform from the level of the platform previously formed to the level of the location of the platform to be mounted and finally the attachment of the other end of the platform to a ladder; the locking of the platform level then includes a large number of locking points both on the guardrails and on the platform. In practice, this implementation therefore proves complicated for the operator. Summary of the invention

[0005] The invention proposes a technical solution to overcome all or part of the drawbacks set out above.

[0006] To this end, the invention proposes a novel scaffolding comprising - a first ladder (10) and a second ladder (10) each having two uprights (11) connected by rungs (12), - two guardrails (20), each guardrail comprising a frame (21) and four fixed plates (22) secured to the frame, each plate being capable of covering and cooperating with a rung of the first ladder or a rung of the second ladder to attach said guardrail to the ladders, - a plate (30) comprising at a first lateral end hooks in the form of grapples (36), said grapple hooks being configured to guide a substantially horizontal movement of bringing the plate into contact with support elements (25a) of the guardrails positioned in the vicinity of the second ladder and configured to cover horizontally an anchoring rung (12a) of the first ladder.

[0007] With a scaffolding according to the invention, and as will be seen more clearly later, after a slight inclination of the platform to slide it a few centimeters between two rungs of the first ladder, the installation of the platform essentially requires horizontal translation movements. Installation is thus facilitated. In addition, in a first movement, the grapple hooks are hooked onto a single element, the anchor rung of the first ladder, which also facilitates assembly. Also, since the support element is carried by the guardrails, it is not possible to install the platform without first having put the guardrails in place. This allows assembly and disassembly of the levels of platforms in complete safety because movement on the platform during installation is made impossible without the presence of the guardrails.

[0008] To facilitate the placement of the grapple hooks of the platform on the anchor bar (12a), the guardrails may also comprise guide elements (25b) configured to guide the placement of the grapple hooks on the anchor bar (12a) of the first ladder, a guide element (25b) of a guardrail being secured to a first vertical upright of the frame and positioned in the vicinity of the first ladder.

[0009] The tray (30) may also comprise, at a second lateral end, a stop means (37) arranged to cooperate with the support element (25a) of a guardrail to prevent translation of the tray in the direction of the first ladder. When the tray is put in place, the stop means are naturally positioned on the lateral side of the support elements (25a) of the guardrails, which further facilitates the putting in place of the tray.

[0010] The frame of a guardrail is conventionally made up of a rail (21a) and a sub-rail (21b) secured to each other by two vertical uprights (21c). According to the invention, the guardrail may also comprise a plinth (21d) secured to the two vertical uprights of the frame and positioned at the platform level. The plinth integrated into the guardrail replaces the longitudinal plinth which must be installed on either side of a scaffolding platform.

[0011] Also, a guardrail can be completed by two gripping elements (21f) positioned under the plinth of the frame to facilitate gripping and installation of the guardrail. Finally, the guardrail can be completed by two bracing elements (21e) and a lower reinforcement (21g) integral with the frame. This replaces the bracing diagonals installed on traditional scaffolding.

[0012] The set of two guardrails thus formed and dimensioned replaces both the guardrails, the longitudinal plinths of the platform and the two diagonals of a traditional scaffolding. The assembly of a platform level of the scaffolding according to the invention is simplified and safer because there is less risk of forgetting a component.

[0013] The scaffolding according to the invention may also comprise a locking pallet (40) movable between a locked position where the pallet immobilizes the platform and the guardrails on the second ladder, and an unlocked position. The pallet thus forms a single lock to simultaneously lock the platform and the guardrails on the ladders, which simplifies the assembly and disassembly of the scaffolding and limits the risks of forgetting a locking point.

[0014] According to one embodiment, the locking pallet (40) comprises a locking finger (41) which, in the locked position, cooperates with an anchoring bar (12b) of the second ladder to keep the platform pressed against the support elements (25a) of the guardrails.

[0015] The platform is locked when it is resting on the guardrails, and the locking blade simultaneously secures the platform, the guardrails and the ladders, and this in a single movement by the operator as will be seen more clearly below.

[0016] In a variant of a scaffolding according to the invention, the platform may comprise a hatch which can rotate between an open position allowing an operator to access above the tray and a closed position; if necessary, the locking pallet may comprise a trapdoor holding finger (42) arranged to, in the unlocked position of the locking pallet, hold the trapdoor in the closed position and, in the unlocked position of the locking pallet, release the trapdoor.

[0017] Thus, the rotation of the hatch is blocked during the handling of the platform, it therefore does not hinder the positioning of the platform. The hatch being released simultaneously with the locking of the platform, access to the upper platform is only authorized after locking the platform; the risks of falling linked to incorrect locking of the platform are thus eliminated. In addition, since the locking of the platform and the opening of the hatch are carried out simultaneously by the movement of a single locking pallet, the assembly time is reduced to a minimum and the operator cannot forget to lock the platform before opening the hatch. The new scaffolding according to the invention, in its most complete version, presents an ultimate level of safety during assembly, dismantling and during its use. Presentation of figures

[0018] The invention will be better understood, and other characteristics and advantages of the invention will appear in the light of the following description of an example of implementation of the invention. This example is given without limitation. The description is to be read in relation to the appended drawings in which: • [Fig.l] is an assembled view of a scaffolding according to the invention, • [Fig.2] is an exploded view of the scaffolding of [Fig.l], • [Fig.3] is a view of a guardrail of the scaffolding of [Fig.l], • [Fig.4] is a detail view A showing the assembly of the elements support of the guardrail of [Fig.3] • [Fig.5] is a view of a detail A of the positioning of the plates of the guardrail of [Fig.3] mounted on the scaffolding of [Fig.l], • [Fig.6] is a view of a platform of the scaffolding of [Fig.l] • [Fig.7] and [Fig.8] are views of details B and C of [Fig.l] showing respectively the connection between the platform and the first ladder, and the connection between the platform and the guardrail, • [Fig.9] is a view of detail F of [Fig.6] showing the locking pallet of the scaffolding of [Fig.l] • [Fig. 10] and [Fig. 11] are detail views D and D' showing the pallet locking the scaffolding of [Fig.l], in the locked position, respectively in the unlocked position.

[0019] In the various figures, identical or similar elements are referenced with the same references.

[0020] The concepts "top", "bottom", "above", "below", "lateral", "front" or "frontal", "rear" or "anterior", are common concepts defined by taking as reference the view of [Fig.l] where the scaffolding is in a position similar to the position it has for normal use after assembly. Detailed description

[0021] As stated previously, the invention relates to a scaffolding comprising in a conventional manner a first ladder and a second ladder 10 and, for each level, a pair of guardrails 20 and a platform 30.

[0022] By convention, the adjective "first" will be used to describe the elements of the scaffolding (first ladder, first end of the platform, first side of a guardrail) which are engaged initially during the assembly of the scaffolding, and the adjective "second" will be used to describe the elements of the scaffolding which are engaged subsequently during the assembly of the scaffolding. In the example shown, the first elements are shown on the right in the figures, e.g. [Fig.l], and the second elements are shown on the left.

[0023] In the illustrated example, each base ladder 10 is provided with wheels 19 to make the scaffolding rolling. The invention is however not limited to this type of scaffolding.

[0024] In the example illustrated also, the scaffolding has a single level. The number of guardrails and the number of platforms can of course be multiplied and the height of the ladders adapted to create scaffolding with several levels.

[0025] Each ladder 10 comprises, in a manner known per se, two uprights 11 connected by bars 12. The ladders consist of one [Fig.l] or more extensions joined to a base element equipped with wheels to adapt the height of the scaffolding to the height of the work to be carried out.

[0026] The guardrails 20 each comprise a frame 21 and four fixed plates 22 secured to the frame [Fig. 3]; each plate is capable of covering and cooperating with a rung of the first ladder or a rung of the second ladder [Fig. 5] to attach the guardrail to the ladders. The plates 22 are positioned on the sides of the frame (here two plates per side), two plates in the upper part and two in the lower part of the frame in order to ensure both a sufficiently large diagonalization between plates and an optimization of the maintenance of the guardrail on the ladders. The plates have a downward opening, they comprise a flat part and an arcuate part; the flat part is configured to rest on the rungs of the ladders to guide and pre-center the guardrail when it is placed between the ladders; the arc-shaped part, open downwards, is configured to center and immobilize the guardrail on the rung capped by the plate. The plates 22 are thus sized and configured to cooperate perfectly with the rungs of the ladders 10.

[0027] The frame of a guardrail is conventionally made up of a rail 21a and a sub-rail 21b secured by two vertical uprights 21c. In the example shown, the guardrail also comprises a plinth 21d secured to the two vertical uprights of the frame and positioned at the platform level. The guardrail is completed here by two gripping elements 21f positioned under the plinth to facilitate gripping and positioning of the guardrail. Finally, the guardrail is completed here by two bracing elements 21e secured to the frame.

[0028] The reinforced guardrail according to the invention thus integrates several functions and therefore allows a great simplification of the assembly of a platform level of the scaffolding while curbing the forgetting or the incorrect locking of a functional element.

[0029] In the context of the invention, a guardrail 20 also comprises a support element 25a [Fig.7] on which the platform rests when it is put in place. The support element is positioned in the vicinity of the second ladder.

[0030] The tray 30 is conventionally made by two side members 31 supporting a floor 32. The center distance between the side members 31 is maintained by two center distance bars 34, one at each end of the side members 31; a third center distance bar is added here in an intermediate position. The floor, at least for its fixed part, is held to the side members in particular by grooves 35; rivets can be added to immobilize the floor in the grooves. Also, in the example shown [Fig.6], a handle 38 and an offset center distance bar 34a are also provided for gripping and handling the tray.

[0031] In the context of the invention, the platform additionally comprises, at a first lateral end of the platform, two hooks in the form of grapples 36 [Fig. 6]; the hook-grapples 36 are configured to guide a substantially horizontal movement of bringing the platform into contact with the support elements 25a of the guardrails positioned in the vicinity of the second ladder and are configured to horizontally cover an anchoring bar 12a of the first ladder [Fig. 8].

[0032] In the illustrated example [Fig.8], a grapple hook 36 is fixed to a first end of a spar 31; the internal shape of a grapple hook 36 comprises a flat part 36a forming with the spar an acute angle turned towards the second end of the platform and a part 36b in the form of a portion of a cylinder open towards the second end of the platform and configured to cover the anchoring bar 12a of the first ladder; the movement of the platform relative to the anchor bar 12a of the first ladder is thus guided in translation until the bar is positioned in the cylindrical housing.

[0033] According to the invention, the guardrails may also comprise guide elements 25b configured to guide the placement of the grapple hooks 36 on the anchoring bar 12a of the first ladder; a guide element 25b of a guardrail is secured to a first vertical upright of the frame and is positioned in the vicinity of the first ladder. The guide element 25b facilitates the placement of the platform on the first ladder. The support element 25a holds the platform on the side of the second ladder.

[0034] In the example illustrated [Fig.4], the guide element 25b of a guardrail is produced in an identical manner to the support element 25a of said guardrail; the support element 25a or the guide element 25b carried by the guardrail extends perpendicular to the frame of the guardrail; the guide element 25b is secured to the first vertical upright of the frame and positioned in the vicinity of the first ladder and the support element 25a is secured to the second vertical upright of the frame and positioned in the vicinity of the second ladder. Producing a guide element 25b identical to the support element 25a makes it possible to obtain identical guardrails, which can be installed on one side or the other of the scaffolding. The manufacture of the scaffolding is thus facilitated, as is the assembly of the scaffolding.In a simple embodiment, a guide element 25b or a support element 25a may be a bolt screwed onto the vertical side of the guardrail frame, the body of which extends horizontally towards the inside of the scaffolding. In the example illustrated [Fig.4], an element 25a or 25b comprises a protuberance consisting of a cylindrical spacer 27 extended by a truncated conical spacer 26; the truncated conical spacer is configured to guide the plate laterally when the plate is being placed and the cylindrical spacer is configured to maintain the horizontal position of the plate. The truncated conical spacer and / or the cylindrical spacer may be mounted to rotate; thus, when it is being placed, the plate rolls on the spacers so that friction, forces and wear are limited.

[0035] Also within the scope of the invention, the platform comprises at a second lateral end, stop means 37 arranged to cooperate with the support elements 25a of the guardrails to prevent a translation of the platform likely to break the connection between the grapple hooks 36 and the anchoring bar 12a of the first ladder. In the example illustrated [Fig. 6], for better mechanical strength of the assembly, the platform comprises two stop means 37, one at the second end of each side member 31 of the platform, and each cooperates with a support element 25a of a guardrail. A stop element 37 here has an inclined flat portion 37a configured to help the stop element 37 to cross the support element 25a so that the vertical part 37b comes to be positioned on the outer side of the support element so that the side member of the platform rests on the support element 25a. The stop elements thus facilitate the approach of the platform towards the support elements 25a when the platform is put in place, then prevent a horizontal translation of the platform towards the first ladder, when the platform is resting on the elements 25a.

[0036] In a scaffolding according to the invention [R6], the platform also comprises a locking pallet 40 movable between a locked position where the pallet immobilizes the platform and the guardrails on the second ladder, and an unlocked position. In the example shown, the locking pallet comprises [Fig.9] a locking finger 41 which, in the locked position, cooperates with an anchoring bar 12b of the second ladder to keep the platform pressed against the support elements 25a of the guardrails.

[0037] More specifically, in the example illustrated, the locking pallet 40 is positioned at the second lateral end of the plate 30 and is mounted to be movable in translation along a sliding axis parallel to a longitudinal axis of the plate. According to other embodiments, the locking pallet can be mounted to be movable in rotation along an axis parallel to the anchoring bar 12b.

[0038] In the locked position [Fig. 10], the locking finger 41 comes to bear under the anchoring bar 12b to keep the side member 31 of the platform 30 resting on the support elements 25a of the guardrails 20. The lifting of the platform is prevented by the bar 12b and a fall of the platform is prevented by the support element 25a of the guardrail. The platform 30, the ladders 10 and the guardrails 20 are thus secured together, simultaneously, by the locking finger 4L. In the unlocked position [Fig.l 1], the locking finger 41 is no longer engaged with the bar 12, which allows the platform to be lifted for the dismantling phase.

[0039] In the illustrated example [Fig. 6], the floor 32 comprises a part forming a hatch 33 movable in rotation between an open position allowing an operator to access above the platform and a closed position. The closed position prevents the operator from accessing above the platform. The hatch is here made movable in rotation along an axis parallel to a side member 31 by two hinges fixed to said side member and the edge of the hatch opposite the hinges rests on the other side member [Fig. 6]. In this example, the locking pallet is advantageously completed by a holding finger 42 of the hatch 33 arranged to, in the unlocked position of the locking pallet 40, hold the hatch in the closed position and, in the locked position of the locking pallet 40, release the hatch.

[0040] More precisely in the example illustrated, in the unlocked position [Fig.l 1] of the locking pallet 40, the holding finger 42 is engaged with the hatch 33 and thus prevents the lifting and rotation of the hatch 33 so that the hatch is kept closed. In other words, as long as the platform 30, the ladders 10 and the guardrails 20 are not correctly locked together, access to the platform is impossible. In the locked position [Fig. 10] of the pallet 40, the finger 42 is no longer engaged with the hatch 33 and the hatch is therefore released; this allows the hatch 33 to be lifted by an operator and therefore access to the platform.

[0041] According to the invention, the locking pallet may also comprise a blocking means 47 configured to automatically immobilize the locking pallet 40 when said locking pallet is moved and arrives in the locked position or in the unlocked position.

[0042] In the practical embodiment shown in figures [Fig.9] to [Fig.11], the locking pallet 40 is pierced with two oblong holes 45 extending in the sliding direction of the pallet and the pallet is secured to the plate 30 by fixing means cooperating with the oblong holes to guide the sliding of the pallet. The fixing means are here two screw-nut-spacer systems 46, the screw body of which associated with a spacer is capable of sliding in the oblong holes.

[0043] The locking finger 41 extends towards the outside of the tray, parallel to a longitudinal axis of the tray, to pass under the bar 12 when the pallet slides towards the locking position and thus prevent the tray from being lifted. The trapdoor holding finger 42 also extends parallel to a longitudinal axis of the tray but in the opposite direction (i.e. towards the inside of the tray) and in a position suitable for engaging the trapdoor when the pallet slides towards the unlocked position of the tray and thus preventing access above the tray. In the example shown [Fig.l 1], the finger 42 engages the trapdoor by passing above the trapdoor. Alternatively, the finger 42 may cooperate with an engagement eye positioned under the trapdoor.

[0044] In the example illustrated [Fig.9] to [Fig.11] again, the locking means comprises, on the locking pallet 40, a spring-loaded finger 47 configured to automatically engage in one of the two holes (not shown in the figures) of the side member 31, two holes defining for one the locked position and for the other the unlocked position. Thus engaged, the locking pallet 40 is immobilized in the locked or unlocked position and cannot move accidentally. Human intervention is then necessary to release the platform and the guardrails.

[0045] The locking means 47 automatically engages in the locked or unlocked position of the locking pallet, which ensures in the locked position that the locking finger 41 remains in position under the bar 12b and in the unlocked position that the locking finger 41 does not open and prevent the tray from being put in place and that the hatch remains blocked through the holding finger 42.

[0046] Assembly of the scaffolding

[0047] The assembly of a level of a scaffolding as described above is carried out in the following manner. The assembly of a guardrail 20 is carried out by engaging the guardrail between the ladders from the ground or from the last level of the platform formed in order to position the four plates 22 on the ladder rungs 12 associated with each hook. The centering and longitudinal positioning of a guardrail is ensured by the shape of the end of the plates 22. Once the two guardrails are installed and positioned in abutment against the vertical uprights of the ladders, the platform 30 can be taken in hand using the handle 38 and the offset center distance bar 34a and engaged between the guardrails.The first end of the platform equipped with the grapple hooks 36 is sent between two rungs of the first ladder, leaning if necessary on the support elements 25b located on the side of the first ladder to facilitate the maneuver; the platform is then lifted horizontally then moved horizontally until [Fig.8] the platform 30 comes to rest on the support elements 25a of the guardrails and the stop elements 37 are positioned towards the outside of the support elements 25a located on the side of the second ladder. The platform, guardrail and ladder assembly is then locked by a longitudinal movement of the locking pallet 40).

[0048] The platform thus installed is immobilized longitudinally in one direction by the grapple hooks 36 engaged with an anchoring bar 12a of the first ladder and in the other direction by the stopping means 37 of the guardrails engaged with the support elements 25a of the guardrails. The platform is also self-centered and immobilized laterally at its two ends by the support elements 25a and the guide elements 25b of the guardrails, themselves immobilized laterally by their plates 22 bearing against the vertical uprights of the ladders. Finally, the anti-lifting of the platform and the guardrails is ensured, on the side of the first ladder, by the shape of the grapple hooks 36 which cover the anchoring bar 12a of the first ladder and, on the side of the second ladder, by the self-locking pallet 40 whose locking finger 41 is positioned under the anchoring bar 12b of the second ladder.

[0049] The invention has been described with the support of an illustrated example representing a rolling scaffolding with a single level. The invention obviously applies to any type of scaffolding, rolling or not, comprising levels mounted one by one from the bottom.

[0050] In summary, the invention proposes a multi-level scaffolding which, at least in its most advanced version, provides all or part of the following advantages: • an impossibility of assembling a platform before the guardrails are in place; which makes the assembly and dismantling of the scaffolding safe, self-positioning of the platform and guardrails in relation to the ladders when the platform is put in place, which facilitates the assembly of the scaffolding self-centering of the tray when it is put in place in order to distribute the play between the tray and the longitudinal plinths integrated into the guardrails a simplification of scaffolding assembly by limiting the number of components to be installed a single lock to simultaneously lock the platform and the guardrails on the ladders, which simplifies the assembly and disassembly of the scaffolding and limits the risk of forgetting a locking point an inability to access the platform until it is locked onto the ladders, the hatch being blocked, which provides an ultimate level of security. Nomenclature

[0051] 10 scales

[0052] 11 amount of a ladder

[0053] 12 rungs of a ladder

[0054] 12a, 12b anchoring bar of the first ladder, respectively of the second ladder

[0055] 19 wheels

[0056] 20 guardrails

[0057] 21 frame

[0058] 21a smooth

[0059] 21b under-smooth

[0060] 21c vertical amount

[0061] 2 Id plinth

[0062] 21st bracing element

[0063] 2If gripping element

[0064] 21g lower frame reinforcement element.

[0065] 22 turntables

[0066] 25a support element

[0067] 25b guide element

[0068] 26 truncated cone spacer

[0069] 27 cylindrical spacer

[0070] 30 platform

[0071] 31 side members

[0072] 32 floor

[0073]

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089] 33 hatch 34 center distance bar 34a offset center distance bar 35 grooves 36 grapple hooks 36a flat part 36b cylinder portion part 37 stop element 37a flat part 37b vertical part 38 handle 40 locking paddle 41 tray locking finger 42 hatch holding finger 45 oblong holes 46 fixing means 47 blocking means

Claims

Claims

1. Scaffolding comprising - a first ladder (10) and a second ladder (10) each having two uprights (11) connected by rungs (12), - two guardrails (20), each guardrail comprising a frame (21) consisting of a rail (21a) and a sub-rail (21b) secured to each other by two vertical uprights (21c), each guardrail also comprising four fixed plates (22) secured to the frame, each plate being capable of covering and cooperating with a rung of the first ladder or a rung of the second ladder to hook said guardrail to the ladders, each guardrail also comprising a support element (25a) positioned in the vicinity of the second ladder, secured to the second vertical upright of the frame of the guardrail and extending perpendicular to the frame of said guardrail, - a platform (30) comprising at a first lateral end hooks in grapple shape (36),said grapple hooks being configured to guide a substantially horizontal movement of bringing the platform up to a support on the support elements (25a) of the guardrails and configured to come horizontally over an anchoring bar (12a) of the first ladder.,

2. Scaffolding according to the preceding claim, in which the guardrails also comprise guide elements (25b) configured to guide the placement of the grapple hooks on the anchor bar of (12a) the first ladder, a guide element (25b) of a guardrail being secured to a first vertical upright of the frame and positioned in the vicinity of the first ladder.

3. Scaffolding according to one of the preceding claims in which the platform (30) also comprises, at a second lateral end, a stopping means (37) arranged to cooperate with the support element (25a) of a guardrail to prevent translation of the platform in the direction of the first ladder.

4. Scaffolding according to one of the preceding claims in which the frame of a guardrail also comprises a plinth (21d) secured to the two vertical uprights of the frame and positioned at the platform level.

5. Scaffolding according to the preceding claim in which a guardrail also comprises gripping elements (21f) positioned under the plinth of the frame.

6. Scaffolding according to one of the preceding claims also comprising a locking pallet (40) movable between a locked position where the pallet immobilizes the platform and the guardrails on the second ladder, and an unlocked position.

7. Scaffolding according to the preceding claim in which the locking pallet (40) comprises a locking finger (41) which, in the locked position, cooperates with an anchoring bar (12b) of the second ladder to keep the platform supported on the support elements (25a) of the guardrails.

8. Scaffolding according to the preceding claim in which the platform comprises a hatch which can rotate between an open position allowing an operator to access above the platform and a closed position, and in which the locking pallet comprises a holding finger (42) of the hatch arranged to, in the unlocked position of the locking pallet, hold the hatch in the closed position and, in the locked position of the locking pallet, release the hatch.

9. Scaffolding according to one of claims 6 to 8 wherein the locking pallet also comprises a blocking means configured to automatically immobilize the locking pallet when said locking pallet is moved and arrives in the locked position or in the unlocked position.

10. Scaffolding according to one of claims 6 to 9 in which the locking pallet is positioned at the second lateral end of the platform and is mounted to move in translation relative to the platform along a sliding axis parallel to the platform.

11. Scaffolding according to the preceding claim in which the locking pallet is pierced with two oblong holes extending parallel to the sliding axis of the pallet and is secured to the platform by fixing means cooperating with the oblong holes to guide the sliding of the pallet.

12. Scaffolding according to the preceding claim in which a support element (25a) or a guide element (25b) comprises a protuberance consisting of a frustoconical spacer extended by a cylindrical spacer, the frustoconical spacer being configured to guide the tray when placing the tray and the cylindrical spacer being configured to maintain a horizontal position of the tray.

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