Overhanging unloading platform anti-falling device

Abstract

The present application provides a kind of cantilever unloading platform anti-falling device, related to unloading platform technology, specifically discloses platform structure, cantilever structure, stabilizing frame and wall bracket, stabilizing frame is installed to the outside of floor along the height direction of floor;Cantilever structure is slidably arranged on the side wall of platform structure, and the drive mechanism for driving the reciprocating motion of cantilever structure along the extension direction of platform structure is provided in platform structure;Limiting mechanism is provided in cantilever structure, and limiting mechanism is used to lock cantilever structure in floor;Stabilizing frame and platform structure can slide relative to each other, wall bracket is installed in stabilizing frame, and adjusting mechanism is installed between wall bracket and stabilizing frame, and wall bracket and stabilizing frame climb along the extension direction of floor under the drive of adjusting mechanism;Cantilever structure is horizontally telescopic and enters into floor to ensure the contact area of platform structure and floor;Adjusting mechanism drives wall bracket to climb along stabilizing frame perpendicular to floor, ensures the accurate moving direction, and can adapt to different floor height requirements.

Description

Technical Field

[0001] This invention relates to the field of unloading platform technology, and more specifically, to a fall prevention device for a cantilevered unloading platform. Background Technology

[0002] Material unloading platforms are temporary workbenches and frames commonly erected on construction sites, generally used for material handling. They are categorized into mobile unloading platforms, floor-mounted unloading platforms, and cantilevered unloading platforms. Generally, floor-mounted unloading platforms are used for buildings of three stories or less, while cantilevered unloading platforms are used for buildings of more than three stories. Mobile unloading platforms are used when flexible construction is required. Currently, most unloading platforms are built according to the construction site conditions. As the number of floors increases, the materials used to build the unloading platform need to be disassembled and reassembled, making it difficult to increase the height of the unloading platform within the existing structure.

[0003] There are currently two main handling methods: installing a freight or passenger / freight elevator. This method is limited by the available space for elevator use and has three drawbacks: strict requirements for installation location, insufficient tonnage, and restrictions on material size; or using a tower crane (which can only lift goods to the roof or a floor with no obstacles on the vertical surface) to lift them to the target floor. On-site, a fixed unloading platform needs to be installed along the edge of the target floor. The disadvantage is that an unloading platform needs to be installed on each floor, which is too large an undertaking. Each unloading platform cannot overlap on the vertical surface, occupying too much area and hindering the exterior decoration of the building. Summary of the Invention

[0004] The purpose of this invention is to provide a fall prevention device for a cantilevered unloading platform, which addresses the shortcomings of existing technologies and solves the problems mentioned in the background.

[0005] The technical solution of this invention is implemented as follows:

[0006] This invention provides a fall prevention device for a cantilevered unloading platform, comprising a platform structure, a cantilever structure, a stabilizing frame, and a wall-mounted frame, wherein the stabilizing frame is installed on the outside of the floor along the height direction of the floor.

[0007] The cantilever structure is slidably mounted on the side wall of the platform structure, and the platform structure is equipped with a drive mechanism for driving the cantilever structure to reciprocate along the extension direction of the platform structure.

[0008] The cantilever structure is equipped with a limiting mechanism, which is used to lock the cantilever structure within the floor.

[0009] The stabilizing frame and platform structure can slide relative to each other. The wall-mounted frame is installed inside the stabilizing frame. An adjustment mechanism is installed between the wall-mounted frame and the stabilizing frame. Driven by the adjustment mechanism, the wall-mounted frame and the stabilizing frame move relative to each other and then climb along the extension direction of the floor.

[0010] In some technical solutions of the present invention, the driving mechanism includes two first hydraulic structures arranged in pairs. The two first hydraulic structures are respectively installed on both sides of the platform structure. The body of the first hydraulic structure is fixed inside the platform structure, and the telescopic end of the first hydraulic structure is connected to the cantilever structure.

[0011] In some technical solutions of the present invention, the limiting mechanism includes two limiting beams arranged in pairs. Two assembly ports corresponding to the two limiting beams are opened on the side wall of the cantilever structure. The limiting beams are rotatably disposed in the assembly ports. Two second hydraulic structures corresponding to the limiting beams are installed on the outer side wall of the cantilever structure. The telescopic ends of the second hydraulic structures are detachably connected to their corresponding limiting beams. The end of the limiting beam placed in the assembly port is equipped with a locking structure that is detachably connected to the floor. The other side of the limiting beam is detachably connected to the main building body.

[0012] In some technical solutions of the present invention, the positioning mechanism includes a third hydraulic structure installed between the stabilizing frame and the wall-mounted frame. The body of the third hydraulic structure is fixed to the side wall of the stabilizing frame, and the telescopic end of the third hydraulic structure is connected to the wall-mounted frame. A guide seat is installed on the stabilizing frame, and a guide frame connected to the wall-mounted frame slides in the guide seat. Both the wall-mounted frame and the stabilizing frame are detachably connected to the building.

[0013] In some technical solutions of the present invention, the locking structure includes a limiting seat and a locking seat. The locking seat is fixed in the floor. A limiting groove is opened on the side wall of the locking seat. The limiting seat is sleeved on the end of the limiting beam. A limiting spring adapted to the limiting seat is installed on the side wall of the limiting beam. A portion of the limiting seat is embedded in the locking seat.

[0014] In some technical solutions of the present invention, the top of both the wall mount and the stabilizer is provided with a rotating shaft, a card seat is installed on the rotating shaft, and a locking structure is provided inside the wall mount to limit the rotation of the card seat.

[0015] In some technical solutions of the present invention, the locking structure includes a torsion spring installed on the rotating shaft, a locking plate installed on the rotating shaft, the locking plate and the card seat being parallel to each other, a limit frame being installed in the wall-mounted frame or the stabilizing frame, and a locking groove adapted to the limit frame being provided on the locking plate.

[0016] In some technical solutions of the present invention, the side wall of the platform structure is provided with a diagonal support that rotates, the diagonal support is connected to the cantilever structure through a transmission, and a telescopic structure is installed on the extension end of the diagonal support, the telescopic end of the telescopic structure is embedded in the stabilizer.

[0017] In some technical solutions of the present invention, the platform structure includes a carrying rack, a material carrying platform is installed inside the carrying rack, and protective structures are installed on both sides of the carrying rack.

[0018] In some technical solutions of the present invention, the cantilever structure includes two cantilever beams arranged in pairs, with reinforcing ribs installed between the two cantilever beams.

[0019] Compared with the prior art, the present invention has at least the following advantages or beneficial effects: Two sets of first hydraulic structures synchronously drive the cantilever structure to extend and retract horizontally into the floor, increasing the contact area between the platform structure and the floor, and preventing tilting or overturning; the third hydraulic structure and guide seat in the adjustment mechanism drive the wall-mounted frame to climb vertically along the stabilizing frame, ensuring precise movement direction, adapting to different floor height requirements, eliminating the need for frequent manual disassembly and assembly, and improving construction efficiency; during the extension and retraction of the cantilever structure, the gear and rack linkage drives the inclined support to rotate from horizontal to inclined, forming active support; the telescopic structure located on the inclined support is embedded in the limiting groove of the stabilizing frame, forming a lateral... Triangular supports enhance the platform's resistance to bending and impact. A second hydraulic structure drives the limiting beam to rotate to a vertical position, strengthening the connection between the cantilever structure and the floor. Through the combined action of the limiting beam and the second hydraulic structure within the limiting mechanism, along with the limiting seat and locking seat within the positioning structure, a double anchoring is formed, achieving a rigid connection between the limiting beam and the floor frame. The positioning structure uses a limiting spring to push the limiting seat into the limiting groove of the pre-embedded locking seat, achieving mechanical engagement, eliminating structural gaps, and preventing slippage. The locking structure (a combination of torsion spring, locking plate, and limiting frame) located on the wall-mounted frame or stabilizing frame automatically restricts the rotation of the locking seat, preventing the wall-mounted frame from detaching from the floor. Attached Figure Description

[0020] Figure 1 This is a three-dimensional structural diagram of the present invention.

[0021] Figure 2 Based on the present invention Figure 1 A frontal view of the structure.

[0022] Figure 3 Based on the present invention Figure 1 A side view structural diagram.

[0023] Figure 4 This is a top view schematic diagram of the platform structure and cantilever structure in this invention.

[0024] Figure 5 This is a schematic diagram of the assembly structure of the limiting beam and the floor in this invention.

[0025] Figure 6 This is a schematic diagram of the mounting structure of the card holder in this invention.

[0026] Figure 7 This is a schematic diagram of the installation structure of the diagonal support in this invention.

[0027] Attached reference numerals: 1. Floor; 2. Loading rack; 3. Cantilever beam; 4. Stabilizing frame; 5. Limiting beam; 6. Second hydraulic structure; 7. Diagonal support; 8. Telescopic structure; 9. Protective structure; 10. Card seat; 11. Loading platform; 12. Wall-mounted frame; 13. Guide frame; 14. Guide seat; 15. Third hydraulic structure; 16. First hydraulic structure; 17. Assembly port; 18. Reinforcing rib; 19. Limiting seat; 20. Limiting spring; 21. Locking plate; 22. Limiting frame; 23. Rack; 24. Gear; 25. Locking seat. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0030] Example

[0031] This invention provides a fall prevention device for a cantilevered unloading platform, such as... Figures 1-7 As shown, the system includes a platform structure, a cantilever structure, a stabilizing frame 4, and a wall-mounted frame 12. The stabilizing frame 4 is a frame structure, channel steel, or I-beam. The stabilizing frame 4 is installed on the outside of floor 1 along the height direction of floor 1. The cantilever structure is slidably mounted on the side wall of the platform structure and is perpendicular to floor 1. The platform structure is equipped with a drive mechanism for driving the cantilever structure to reciprocate along the extension direction of the platform structure. The cantilever structure is equipped with a limiting mechanism to lock the cantilever structure within floor 1, forming a rigid connection between the two. The stabilizing frame 4 and the platform structure can slide relative to each other. The wall-mounted frame 12 is installed inside the stabilizing frame 4. An adjustment mechanism is installed between the wall-mounted frame 12 and the stabilizing frame 4. Driven by the adjustment mechanism, the wall-mounted frame 12 and the stabilizing frame 4 move relative to each other and then climb along the extension direction of floor 1.

[0032] The working principle of the unloading platform is as follows: the two first hydraulic structures 16 in the drive mechanism adjust the cantilever structure to extend and retract horizontally relative to floor 1 and enter floor 1 to contact the floor surface, so that the platform structure is accurately positioned in the construction area, which facilitates unloading.

[0033] The limiting beam 5 in the limiting mechanism locks the cantilever structure in the floor 1 by adjusting the second hydraulic structure 6. The locking structure is physically fixed by engaging the limiting seat 19 with the locking seat 25 pre-embedded in the floor, thereby improving the connection strength between the two.

[0034] The third hydraulic structure 15 in the adjustment mechanism, together with the guide seat 14, drives the wall-mounted frame 12 to climb vertically along the stabilizer 4, adapting to different floor heights. The wall-mounted frame 12 and the stabilizer 4 move alternately under the drive of the third hydraulic structure 15, so that the above structure can climb along the height of the floor. The rotating shaft set on the wall-mounted frame 12 and the card seat 10 are designed to achieve quick fixation. The locking structure torsion spring and locking plate 21 cooperate to prevent accidental rotation, which would cause the wall-mounted frame 12 to lose contact with the floor.

[0035] In some technical solutions of the present invention, the driving mechanism includes two first hydraulic structures 16 arranged in pairs. The two first hydraulic structures 16 are respectively installed on both sides of the platform structure. The body of the first hydraulic structure 16 is fixed to the side wall of the platform structure by a high-strength nut. The telescopic end of the first hydraulic structure 16 is connected to the cantilever structure. The first hydraulic mechanism provides smooth power for the horizontal sliding of the cantilever structure, ensuring the precise extension and retraction of the cantilever structure. The cantilever structure is a frame structure composed of double cantilever beams 3 and reinforcing ribs 18. Through the synchronous extension and retraction of the first hydraulic mechanism on both sides of the platform structure, the horizontal movement of the platform is realized, allowing a part of the platform structure to enter the floor 1, thereby driving the platform structure to be precisely positioned at the unloading position and preventing the platform structure from overturning during the unloading process.

[0036] Preferably, the cantilever beam 3 is an I-beam or a channel steel.

[0037] In some technical solutions of the present invention, the limiting mechanism consists of two limiting beams 5 arranged in pairs. The limiting beams 5 are I-beams or channel steels. Two assembly ports 17, each corresponding to one of the two limiting beams 5, are opened on the side wall of the cantilever structure. The assembly ports 17 are rectangular. The limiting beams 5 are rotatably mounted in the assembly ports 17 via high-strength shafts. Two second hydraulic structures 6, each corresponding to one of the limiting beams 5, are installed on the outer side wall of the cantilever structure. The bodies of the second hydraulic structures 6 are also rotatably mounted on the outer side wall of the cantilever beam 3 via pins. The telescopic ends of the second hydraulic structures 6 are detachably connected to their corresponding limiting beams 5 via pins. The end of the limiting beam 5 placed in the assembly port is equipped with a locking structure that can be detachably connected to the floor. The other side of the limiting beam 5 is detachably connected to the main body of the building via bolts or by fastening with a U-shaped seat. Two sets of second hydraulic mechanisms control the angle of the limiting beam 5 on the cantilever structure until the limiting beam 5 is perpendicular to the cantilever structure and abuts against the frame structure of the upper floor, achieving a rigid connection with the floor. Furthermore, the lower part of the limiting beam 5 rotates under the drive of the second hydraulic mechanism and locks with the building through the locking structure, forming a double anchoring, which improves the stability of the cantilever structure and platform structure when connected to the main floor.

[0038] In some technical solutions of the present invention, the adjustment mechanism includes a third hydraulic structure 15 installed between the stabilizing frame 4 and the wall-mounted frame 12. The body of the third hydraulic structure 15 is fixed to the side wall of the stabilizing frame 4 by bolts. The telescopic end of the third hydraulic structure 15 is connected to the wall-mounted frame 12. A guide seat 14 is installed on the stabilizing frame 4. A guide frame 13 connected to the wall-mounted frame 12 slides inside the guide seat 14. Both the wall-mounted frame 12 and the stabilizing frame 4 are equipped with components that can be detachably connected to the building structure. When the adjustment mechanism pushes the wall-mounted frame 12 to move along the stabilizing frame 4 through the third hydraulic structure 15, the guide seat 14 ensures the verticality of the wall-mounted frame 12 during movement. When the third hydraulic mechanism drives the wall-mounted frame 12 to climb vertically along the guide frame 13, the limiting beam 5 releases the lock on the cantilever structure, and the driving mechanism drives the cantilever structure back into the platform structure. In this way, the adjustment mechanism can adapt to changes in the height of the floor 1. The stabilizing frame 4 and the wall-mounted frame 12 climb step by step through hydraulic drive, and the guide seat 14 ensures accurate movement direction to meet the height requirements of different floors 1.

[0039] In some technical solutions of the present invention, the locking structure includes a limiting seat 19 and a locking seat 25. The locking seat 25 is fixed to the floor by bolts. A limiting groove is formed on the side wall of the locking seat 25. The limiting seat 19 is sleeved on the end of the limiting beam 5. A limiting spring 20 adapted to the limiting seat 19 is installed on the side wall of the limiting beam 5. The limiting seat 19 is partially embedded in the locking seat 25. When the limiting beam 5 is controlled by the second hydraulic mechanism to adjust the angle of the limiting beam 5 on the cantilever structure until the limiting beam 5 is perpendicular to the cantilever structure and abuts against the frame structure of the upper floor, the limiting spring 20 will gradually push the limiting seat 19 into the locking groove to form a mechanical lock. After the limiting seat 19 is fully embedded in the locking groove, the locking seat 25 and the limiting frame 22 form a rigid stop.

[0040] In some technical solutions of the present invention, the top of both the wall-mounted frame 12 and the stabilizer 4 are rotatably provided with a rotating shaft, and a card seat 10 is installed on the rotating shaft. The wall-mounted frame 12 is provided with a locking structure for restricting the rotation of the card seat 10.

[0041] In some technical solutions of this invention, the locking structure includes a torsion spring mounted on the rotating shaft (not shown in the figures). A locking plate 21 is mounted on the rotating shaft, and the locking plate 21 is parallel to the card seat 10. A limit frame 22 is installed inside the wall-mounted frame 12 or the stabilizing frame 4. The locking plate 21 is provided with a locking groove that matches the limit frame 22. The torsion spring drives the locking plate 21 to engage with the limit frame 22, preventing the card seat 10 from loosening. The multiple locking mechanisms (card seat structure and locking plate 21) prevent the platform from slipping or falling. The second hydraulic cylinder drives the limit beam 5 to rotate and press down. The limit spring 20 causes the limit seat 19 to elastically engage with the floor locking seat 25, eliminating structural gaps. The rotating shaft and the card holder 10 achieve unidirectional rotation through a torsion spring, and can also automatically reset. When the locking plate 21 and the slot of the limiting frame 22 are engaged to complete the fixation, the card holder 10 automatically snaps into the building structure under the action of the torsion spring, locks with the building body, and forms a double anchor, which improves the stability of the cantilever structure and platform structure when connected to the main floor.

[0042] Preferably, during long-term construction, the locking plate 21 can be fixed to the floor surface with bolts.

[0043] In some technical solutions of this invention, a diagonal support 7 is rotatably provided on the side wall of the platform structure. The diagonal support 7 is connected to the cantilever structure via a transmission connection. A telescopic structure 8 is installed on the extended end of the diagonal support 7, and the telescopic end of the telescopic structure 8 is embedded in the stabilizer 4. The diagonal support 7 and the telescopic structure 8 dynamically adjust the support angle according to the platform load to enhance the anti-overturning capability. The diagonal support 7 is linked with the cantilever structure, and lateral reinforcement is achieved by embedding the telescopic structure 8 into the stabilizer 4. The telescopic structure 8 inserted into the stabilizer 4 forms a triangular support.

[0044] Preferably, a plurality of limiting openings are provided on the side wall of the stabilizer along its extension direction, and the limiting openings are adapted to the telescopic ends of the telescopic structure 8.

[0045] The transmission structure between the inclined support 7 and the cantilever structure is as follows: a rack 23 is installed on the cantilever structure and is fixedly connected to the cantilever structure. The inclined support 7 is rotatably set on the side of the platform structure away from the floor via a pin shaft. A gear 24 that meshes with the rack 23 is installed on the outer wall of the inclined support 7. Thus, when the double first hydraulic structure 16 in the drive mechanism adjusts the cantilever structure to extend horizontally relative to floor 1 and enters floor 1 to contact the floor surface, the cantilever structure will pull the rack 23 closer to the floor. At this time, the rack 23 will drive the gear 24 to move clockwise. Thus, the inclined support 7 will gradually change from a state parallel to the platform structure to an inclined state. When the cantilever structure enters floor 1 and stops moving forward, the inclined support 7 stops rotating. Then, the telescopic structure 8 installed on the extension end of the inclined support 7 is activated by the operator. The telescopic end of the telescopic structure 8 gradually extends out of its body and is then embedded in the limiting groove set on the stabilizer 4 to achieve lateral reinforcement of the platform structure.

[0046] In some technical solutions of this invention, the platform structure includes a carrying frame 2, within which a material-carrying platform 11 is bolted. Protective structures 9 are installed on both sides of the carrying frame 2. The protective structures 9 on both sides of the carrying frame 2 (such as railings or safety nets) prevent materials from falling, and, combined with construction load-limiting measures, ensure operational safety.

[0047] In some technical solutions of this invention, the cantilever structure includes two cantilever beams 3 arranged in pairs, with a reinforcing rib 18 installed between the two cantilever beams 3. The cantilever beams 3 and the reinforcing rib 18 are fixed by welding or bolts to ensure the connection strength between the two and improve the stability of the structure when bearing the load of the platform structure.

[0048] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fall prevention device for a cantilevered unloading platform, characterized in that, It includes a platform structure, a cantilever structure, a stabilizing frame (4) and a wall-mounted frame (12), wherein the stabilizing frame (4) is installed on the outside of the floor (1) along the height direction of the floor (1); The cantilever structure is slidably mounted on the side wall of the platform structure, and the platform structure is provided with a drive mechanism for driving the cantilever structure to reciprocate along the extension direction of the platform structure. The cantilever structure is provided with a limiting mechanism, which is used to lock the cantilever structure within the floor (1); The stabilizing frame (4) and the platform structure can slide relative to each other. The wall-mounted frame (12) is installed inside the stabilizing frame (4). An adjustment mechanism is installed between the wall-mounted frame (12) and the stabilizing frame (4). The wall-mounted frame (12) and the stabilizing frame (4) move relative to each other under the drive of the adjustment mechanism and then climb along the extension direction of the floor (1). The limiting mechanism includes two limiting beams (5) arranged in pairs. Two assembly ports (17) corresponding to the two limiting beams (5) are opened on the side wall of the cantilever structure. The limiting beams (5) are rotatably arranged in the assembly ports (17). Two second hydraulic structures (6) corresponding to the limiting beams (5) are installed on the outer side wall of the cantilever structure. The telescopic end of the second hydraulic structure (6) is detachably connected to its corresponding limiting beam (5). The end of the limiting beam (5) placed in the assembly port is equipped with a locking structure that can be detachably connected to the floor. The other side of the limiting beam (5) is detachably connected to the main building. The adjustment mechanism includes a third hydraulic structure (15) installed between the stabilizer (4) and the wall-mounted frame (12). The body of the third hydraulic structure (15) is fixed to the side wall of the stabilizer (4). The telescopic end of the third hydraulic structure (15) is connected to the wall-mounted frame (12). A guide seat (14) is installed on the stabilizer (4). A guide frame (13) connected to the wall-mounted frame (12) slides inside the guide seat (14). Both the wall-mounted frame (12) and the stabilizer (4) are detachably connected to the floor (1). The locking structure includes a limiting seat (19) and a locking seat (25). The locking seat (25) is fixed in the floor. A limiting groove is provided on the side wall of the locking seat (25). The limiting seat (19) is sleeved on the end of the limiting beam (5). A limiting spring (20) adapted to the limiting seat (19) is installed on the side wall of the limiting beam (5). A portion of the limiting seat (19) is embedded in the locking seat (25). The top of both the wall-mounted frame (12) and the stabilizer (4) is provided with a rotating shaft, and a card seat (10) is installed on the rotating shaft. The wall-mounted frame (12) is provided with a locking structure for limiting the rotation of the card seat (10). The locking structure includes a torsion spring installed on the rotating shaft, a locking plate (21) installed on the rotating shaft, the locking plate (21) being parallel to the card seat (10), a limit frame (22) being installed in the wall mount (12) or the stabilizing frame (4), and a locking groove adapted to the limit frame (22) being provided on the locking plate (21).

2. The anti-fall device for a cantilevered unloading platform according to claim 1, characterized in that, The drive mechanism includes two first hydraulic structures (16) arranged in pairs. The two first hydraulic structures (16) are respectively installed on both sides of the platform structure. The body of the first hydraulic structure (16) is fixed inside the platform structure, and the telescopic end of the first hydraulic structure (16) is connected to the cantilever structure.

3. The anti-fall device for a cantilevered unloading platform according to claim 1, characterized in that, The platform structure is provided with a rotatable inclined support (7) on its side wall. The inclined support (7) is connected to the cantilever structure. A telescopic structure (8) is installed on the extension end of the inclined support (7). The telescopic end of the telescopic structure (8) is embedded in the stabilizer (4).

4. The anti-fall device for a cantilevered unloading platform according to claim 1, characterized in that, The platform structure includes a carrying rack (2), a material carrying platform (11) is installed inside the carrying rack (2), and protective structures (9) are installed on both sides of the carrying rack (2).

5. The anti-fall device for a cantilevered unloading platform according to claim 1, characterized in that, The cantilever structure includes two cantilever beams (3) arranged in pairs, with reinforcing ribs (18) installed between the two cantilever beams (3).

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