Rail-mounted lifting crane for construction of petrochemical steel structure platforms

Abstract

The present application relates to the technical field of hoisting equipment, and discloses a track type lifting crane for petrochemical steel structure platform construction, which comprises a guide carriage installed on a top girder of a steel structure platform, a hoisting device capable of moving on the guide carriage, a movable base installed on the ground and capable of moving along a ground guide rail, a vertical directional guide rail arranged on the movable base, and a hoisting platform capable of sliding and lifting on the directional guide rail. The hoisting device is connected with the top end of the directional guide rail through a coupling frame. The hoisting platform is in a telescopic form. Through the coordinated translation of the top and the ground rail, the present application can be flexibly moved along the entire length direction of the platform and accurately deliver materials to the vicinity of the work surface of different regions. Compared with the traditional elevator which can only unload materials at a fixed point, the present application does not need to set up a fixed overhanging material receiving platform, can dynamically select the best feeding point according to the construction progress, significantly shortens the secondary handling distance of the materials in the platform, and greatly improves the material turnover efficiency.

Description

Technical Field

[0001] This invention relates to the field of lifting equipment technology, and in particular to a rail-mounted lifting crane suitable for the construction phase of large steel structure platforms in the petrochemical, energy and other fields, which can achieve efficient and precise vertical material transport. Background Technology

[0002] Large-scale petrochemical projects typically employ multi-layered, open steel structure platforms. In the later stages of platform construction, after the main steel structure is erected and large and medium-sized equipment such as towers and heat exchangers, as well as the main pipeline system, are in place, the internal space becomes complex, and traditional material transportation methods face severe challenges.

[0003] Limitations of traditional tower cranes: While tower cranes offer a wide coverage area, their hooks are flexibly connected, making it difficult for hoisted materials to sway due to factors such as wind, and thus difficult to deliver precisely to designated work points within the structure. Furthermore, they pose a significant risk of collision, seriously threatening construction safety.

[0004] Bottlenecks of construction hoists: Conventional construction hoists (cage ladders) are typically limited to serving only a specific area of ​​the platform due to their fixed installation location. To receive materials, a cantilevered receiving platform must be erected on the corresponding floor. For large steel structure platforms, materials still require long-distance secondary handling after reaching the cantilevered platform before being delivered to other work points within the platform. For large quantities or long strips of materials such as cables, pipes, and scaffolding, this secondary handling is not only extremely inefficient but also prone to causing congestion and safety hazards within the complex space and pipeline layout of the platform.

[0005] In conclusion, during the construction phase of petrochemical steel structure platforms, there is an urgent need for a new type of material conveying equipment that can overcome the drawbacks of traditional methods and enable the safe, efficient, and precise transport of ground materials to designated high-altitude work surfaces. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a rail-mounted lifting crane for the construction of petrochemical steel structure platforms, which aims to solve the problems of high safety risks, low efficiency and long-distance secondary handling of materials in the prior art.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A rail-mounted lifting crane for the construction of petrochemical steel structure platforms includes: Guide carriage, which is installed on the frame structure at the top of the steel structure platform; The lifting device can travel along the length of the guide carriage. The boom of the lifting device extends from the edge of the platform and is equipped with an electric chain hoist for lifting. A movable base is installed on a ground guide rail below the steel structure platform. The movable base is vertically provided with a pair of parallel directional guide rails. The ground guide rails are laid along the length of the steel structure platform and are parallel to the guide carriage. The lifting platform can slide and rise along the directional guide rail, and the lifting platform is connected to the electric chain hoist via slings; And a coupling frame for connecting the boom of the lifting device to the top of the directional guide rail.

[0008] Preferably, the guide carriage is detachably fixed to the top frame structure of the steel structure platform by a number of U-bolts and lugs. This modular installation method allows the device to be easily installed on standardized steel structures, such as load-bearing main beams or crossbeams, ensuring the stability and detachability of the installation. After construction, it can be quickly disassembled and relocated, offering good economy and reusability.

[0009] In this invention, the lifting platform includes a fixed frame and a telescopic frame; the telescopic frame is equipped with a material carrying platform, and the telescopic frame is slidably mounted on the fixed frame and can extend towards the steel structure platform; the telescopic frame also has a cantilever support beam that extends before the material. This two-step extension mechanism of "support first, load following" ensures that there is pre-connected rigid support when the load is extended into the platform, greatly improving stability and operational safety.

[0010] Preferably, the extension and retraction of the cantilever support beam and the telescopic frame are driven by the same driver, which includes a telescopic drive motor and its driven spindle. The spindle simultaneously drives a belt drive system for extending the telescopic frame and a screw drive system for extending the cantilever support beam. Through the precise timing coordination of the belt drive system and the screw drive system, "support first" is automatically achieved. Specifically, the belt drive system includes a drive belt, and the telescopic frame is connected to the drive belt via a buckle. The drive belt has a groove for the stop bar on the buckle to slide within a predetermined stroke, so that the telescopic frame remains stationary during the extension of the cantilever support beam; only when the cantilever support beam is fully extended and the transmission fails does the drive belt begin to push the telescopic frame to extend.

[0011] Furthermore, the lead screw drive system includes a lead screw and a built-in lead screw nut that engages with the lead screw thread; the two ends of the lead screw are respectively provided with a head optical shaft section and a tail optical shaft section without threads; when the built-in lead screw nut is driven to either optical shaft section, its threaded transmission with the lead screw fails, and an elastic element is provided at the optical shaft section to push the built-in lead screw nut back to the threaded section of the lead screw to restore transmission when the motor reverses.

[0012] Preferably, the material carrier platform is a conveyor belt. During the platform construction phase, it is particularly suitable for the continuous and efficient transport of cables, insulation materials, scaffolding fittings, and standardized materials such as boxed bolts and flanges, seamlessly connecting the ground supply station and the high-altitude work surface into a flowing production line.

[0013] In this invention, the guide carriage includes a supporting bottom rail and a supporting top rail, and the main body of the lifting device is located between the two. The bottom of the lifting device is provided with a lifting drive wheel, the top is provided with a top longitudinal anti-torsion guide wheel, and the sides are provided with a bottom transverse anti-torsion guide wheel and a top transverse anti-torsion guide wheel to resist the torsional load generated by the boom.

[0014] In this invention, the coupling frame includes a horizontal frame, a vertical frame, and a fixed base; the connection between the vertical frame and the horizontal frame allows relative movement on the horizontal plane; the connection between the fixed base and the vertical frame allows relative movement in the vertical direction to compensate for installation errors and dynamic deformations of the system during travel.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Achieves flexible material placement along the platform's length, significantly reducing secondary handling distance: Through synchronous translation along the top guide carriage and ground guide rails, this invention can move flexibly along the entire length of the platform. The telescopic function of the lifting platform can directly deliver materials into the platform, accurately delivering materials to the vicinity of different work areas. Compared to traditional elevators that can only unload at fixed points, this invention eliminates the need for a fixed cantilevered receiving platform, allowing for dynamic selection of the optimal loading point based on construction progress. This significantly shortens the secondary handling distance of materials within the platform and greatly improves material turnover efficiency.

[0016] 2. Improved construction efficiency and shorter construction period: Rigid directional guide rails eliminate the swaying problem of traditional hoisting, ensuring precise and rapid positioning. The conveyor belt-type material carrying platform enables continuous operation when transporting large quantities of long, strip-shaped materials such as cables and pipes, achieving efficiency far exceeding that of traditional intermittent hoisting methods.

[0017] 3. Enhanced construction safety: The swing-free, precise docking method avoids the risk of collisions between the suspended load and installed equipment and pipelines. The automated extension and conveying process reduces manual work at height, lowering the risk of operator error.

[0018] 4. Modular design and good economy: All parts of the device are modularly designed, making it easy and quick to install and disassemble. It can be used as a standard construction equipment in different projects, thus improving the utilization rate of the equipment. Attached Figure Description

[0019] Figure 1 This is one of the schematic diagrams of the overall structure of the present invention after installation; Figure 2 yes Figure 1 A magnified view of part A in the middle; Figure 3 yes Figure 1 A magnified view of part B in the middle; Figure 4 This is the second schematic diagram of the overall structure of the present invention after installation; Figure 5 yes Figure 4 A magnified view of part C in the middle; Figure 6 This is a schematic diagram of the lifting device; Figure 7 This is a schematic diagram of the coupling frame; Figure 8 This is a schematic diagram showing the lifting platform after it has been raised into place. Figure 9 This is a schematic diagram of the cantilever support beam of the lifting platform after it has extended. Figure 10 This is a schematic diagram of the material support platform of the hoisting platform after it has been extended. Figure 11 This is one of the structural schematic diagrams of a lifting platform; Figure 12 This is the second structural schematic diagram of the lifting platform; Figure 13 This is a schematic diagram showing the cantilever support beam of the lifting platform extending out and concealing the telescopic frame. Figure 14 yes Figure 13 A magnified view of part D in the middle; Figure 15 yes Figure 13 A magnified view of part E in the middle; Figure 16 This is a schematic diagram showing the lifting platform with its telescopic frame and a cantilever support beam concealed. Figure 17 This is a structural diagram of the telescopic frame; Figure 18 yes Figure 17 A magnified view of part F in the middle; Figure 19 This is a schematic diagram of the cantilever support beam and telescopic frame of the lifting platform in a fully retracted state. Figure 20 This is a schematic diagram of the cantilever support beam of the lifting platform after it has extended (the elastic limiter and the limit baffle are not in contact). Figure 21 This is a schematic diagram of the cantilever support beam of the lifting platform fully extended (elastic limiter and limit baffle in contact). Figure 22 This is a schematic diagram of the extended telescopic frame of the lifting platform. Figure 23This is a schematic diagram showing the cantilever support beam and telescopic frame of the lifting platform beginning to retract; Figure 24 This is a structural schematic diagram of a cantilever support beam; Figure 25 This is a structural diagram of the material support platform.

[0020] In the diagram: 1. Guide carriage; 2. Lifting device; 3. Coupling frame; 4. Directional guide rail; 5. Lifting platform; 6. Moving base; 7. Ground guide rail; 8. Lifting sling; 9. Base drive motor; 10. Lifting guide wheel; 11. U-bolt; 12. Ear plate; 13. Support bottom rail; 14. Support top rail; 15. Hanger body; 16. Hanger drive wheel; 17. Bottom transverse anti-torsion guide wheel; 18. Top transverse anti-torsion guide wheel; 19. Top longitudinal anti-torsion guide wheel; 20. Electric chain hoist; 21. Cross frame; 22. Strip slot; 23. Screw; 24. Cover plate; 25. Longitudinal frame; 26. Sliding bearing; 27. Sliding shaft; 28. Fixed seat; 29. ​​Fixed frame body; 3 0. Telescopic frame; 31. Cantilever support beam; 32. Fixed guide wheel; 33. Sliding guide wheel; 34. Lead screw; 341. Head optical shaft section; 342. Tail optical shaft section; 35. Fixed plate; 36. Bevel gear reversing device; 37. Drive shaft; 38. Bidirectional output reducer; 39. Telescopic drive motor; 40. Drive belt; 41. Lock; 411. Stop bar; 42. Abutment plate; 43. End limiting plate; 44. Compression spring; 45. Elastic limiter; 46. Limiting baffle; 47. Slide; 471. Slide head end; 472. Slide tail end; 48. Long through groove; 49. Material support platform; 50. Built-in lead screw nut; 51. Conveyor belt drive motor. Detailed Implementation

[0021] The present invention will be further described below with reference to specific embodiments.

[0022] The description of the present invention is merely a structural or even functional description of the embodiments, and the scope of the present invention is not limited by the embodiments described herein.

[0023] This embodiment is achieved through the following technical solution: like Figures 1 to 5 As shown, the present invention provides a rail-mounted lifting crane for the construction of a petrochemical steel structure platform. Its main structure, from top to bottom, includes: a guide slide 1 installed on the top of the steel structure platform, a lifting device 2 that travels along the guide slide 1, a coupling frame 3 connecting the lifting device 2 and the directional guide rail 4, a vertically arranged directional guide rail 4, a lifting platform 5 that can slide and rise on the directional guide rail 4, and a movable base 6 located on the ground, supporting the directional guide rail 4 and traveling along the ground guide rail 7.

[0024] Specifically, the guide slide 1 is fixed to the I-beam structural frame on the top layer of the steel structure platform by U-bolts 11 and ear plates 12 welded to both sides of the square tube of the guide slide 1, ensuring the stability and detachability of the installation.

[0025] Ground guide rail 7 is laid on a flat concrete surface in front of the steel structure platform, parallel to the top guide slide 1. The drive system of the lifting device 2 starts and stops synchronously with the moving base drive system powered by the base drive motor 9, so that the entire hoisting system can move smoothly along the length of the steel structure platform, covering the long vertical working surface of the platform.

[0026] like Figure 6 As shown, the lifting device 2 travels on the guide carriage 1. The main body of the guide carriage 1 consists of a bottom support rail 13 and a top support rail 14. The main body 15 of the lifting device 2 is located between the two, and is powered by the bottom drive wheel 16. Simultaneously, the bottom transverse anti-torsion guide wheel 17 (contacting the outer side of the bottom support rail 13), the top transverse anti-torsion guide wheel 18 (contacting the inner side of the top support rail 14), and the top longitudinal anti-torsion guide wheel 19 (contacting the bottom surface of the top support rail 14) work together to effectively resist the torsional torque generated by the boom and load, ensuring its stability and safety. The electric chain hoist 20 extending from the boom is connected to the lifting platform 5 via the sling 8, providing it with lifting power.

[0027] like Figure 7 As shown, the coupling frame 3 is a flexible link connecting the aerial and ground sections. It achieves slight floating in the X, Y, and Z directions through a combination of a horizontal frame 21, a vertical frame 25, and a fixed base 28, utilizing a slotted hole 22 and a sliding shaft 27 / sliding bearing 26 structure. Specifically, the horizontal frame 21 is fixedly connected to the boom, located at the end of the boom and perpendicular to it; the vertical frame 25 and the fixed base 28 each have two sets, located at both ends of the horizontal frame 21, with the fixed base 28 mounted on the directional guide rail 4. The vertical frame 25 is connected to the upper cover plate 24 via four screws 23. The end of the horizontal frame 21 is positioned between the cover plate 24 and the vertical frame 25. The screws 23 are connected to the vertical frame 25 via a slotted hole 22 in the Y-axis direction, thus allowing the vertical frame 25 and the horizontal frame 21 to move relative to each other within a certain range along the X and Y axes. The fixed base 28 is equipped with a vertical sliding shaft 27, and the longitudinal frame 25 is equipped with a matching sliding bearing 26. The sliding shaft 27 is slidably disposed within the sliding bearing 26, thereby enabling the longitudinal frame 25 and the transverse frame 21 to move relative to each other within a certain range along the Z-axis. This is used to absorb and compensate for system deformation caused by uneven track, synchronization errors, etc., and to avoid the generation of rigid stress.

[0028] like Figures 8 to 10The diagram shows the process of hoisting platform 5 docking with the steel structure platform under construction and transporting materials. First, hoisting platform 5 is raised to be level with the pre-set loading port on the platform layer (i.e., the gap in the fence, not shown in the diagram), as... Figure 8 As shown. Then, the telescopic drive motor 39 starts, and the cantilever support beam 31 extends first, its end overlapping the platform floor slab to form a stable pilot support, as shown. Figure 9 As shown. Subsequently, the telescopic frame 30 extends with the material support platform 49 until its front abutment plate 42 contacts the edge of the platform, completing a seamless connection with the construction platform, as shown. Figure 10 As shown. At this time, starting the conveyor belt drive motor 51 on the material carrying platform 49 will continuously transport the material into the platform.

[0029] like Figures 11 to 25 The diagram shows the "two-step" telescopic mechanism inside the lifting platform 5. The telescopic movements of the cantilever support beam 31 and the telescopic frame 30 are controlled by the same telescopic drive motor 39. Through the timing coordination of belt drive and screw drive, a two-step extension mechanism of "support first, load following" is realized.

[0030] Specifically, the lifting platform 5 includes a fixed frame 29 and a telescopic frame 30. The telescopic frame 30 is equipped with a material carrying platform 49. The fixed frame 29 is equipped with fixed guide wheels 32, and the telescopic frame 30 is equipped with sliding guide wheels 33. The telescopic frame 30 is slidably mounted on the fixed frame 29 and can extend towards the steel structure platform. The telescopic frame 30 contains a cantilever support beam 31 that can extend towards the steel structure platform. The cantilever support beam 31 has an end limiting plate 43 at its head, and the telescopic frame 30 has a downward-facing abutment plate 42 at its head. The telescopic support beam 31 and the telescopic frame 30 share a common drive system. The drive system includes a telescopic drive motor 39 and a main shaft driven by it. The output shaft of the telescopic drive motor 39 is equipped with a small gear, and the main shaft is equipped with a large gear. The main shaft simultaneously drives the frame telescopic subsystem and the support beam telescopic subsystem.

[0031] The telescopic frame subsystem is a belt drive system, including a driving pulley, a driven pulley, and a drive belt 40. The driving pulley is mounted on the main shaft at one end of the fixed frame 29, and the driven pulley is located at the other end of the fixed frame 29. The drive belt 40 is installed between the driving pulley and the driven pulley. The telescopic frame 30 is connected to the drive belt 40 through a buckle 41. The drive belt 40 has a long strip-shaped groove 47 along its length direction. The buckle 41 has a transverse stop bar 411 that passes through the groove 47.

[0032] The telescopic subsystem of the support beam is a screw drive system, including a screw 34 and a built-in screw nut 50 located at the end of the cantilever support beam 31. The screw 34 is located inside the cantilever support beam 31, and the built-in screw nut 50 is threadedly connected to the screw 34. One end of the screw 34 is connected to a drive shaft 37 via a bevel gear commutator 36. The drive shaft 37 is connected to the output shaft of a bidirectional output reducer 38, and the main shaft serves as the input shaft of the bidirectional output reducer 38. The two ends of the screw 34 are respectively provided with a head section 341 (without screw thread) and a tail section 342. Both sections are equipped with elastic elements that force the built-in screw nut 50 to engage with the threaded section of the screw 34. The elastic components are a compression spring 44 located at the head optical axis section 341 and an elastic limiter 45 located at the tail optical axis section 342. One end of the compression spring 44 is fixed to the fixed plate 35, and the other end can directly act on one end of the cantilever support beam 31. One end of the elastic limiter 45 is fixed to the fixed frame 29, and the other end can act on the limiting baffle 46 at the other end of the cantilever support beam 31 (the limiting baffle 46 extends from the elongated through groove 48 on the bottom surface of the fixed frame 29).

[0033] When the telescopic drive motor 39 rotates forward, power is transmitted to the lead screw 34 through the bidirectional output reducer 38, drive shaft 37, and bevel gear commutator 36, driving the cantilever support beam 31, which is fixed to the built-in lead screw nut 50, to extend forward. During this process, the stop bar 411 on the latch 41 connected to the telescopic frame 30 slides freely within the long slide groove 47 of the transmission belt 40, thus keeping the telescopic frame 30 stationary. Figure 20 As shown.

[0034] When the cantilever support beam 31 extends into position, its built-in lead screw nut 50 slides into the tail section 342 of the lead screw 34, causing the threaded drive to fail and simultaneously compressing the elastic limiter 45. Figure 21 As shown. At this time, the sliding end 471 of the still rotating transmission belt 40 begins to push the stop lever 411 of the lock 41, thereby causing the telescopic frame 30 to extend forward, as shown. Figure 22 As shown.

[0035] When the telescopic drive motor 39 reverses, the compressed elastic limiter 45 releases energy, pushing the built-in lead screw nut 50 back to the threaded section, restoring transmission. The cantilever support beam 31 begins to retract. Simultaneously, its end limit plate 43 hooks onto the telescopic frame 30, pulling the telescopic frame 30 back together, achieving synchronous retraction. Figure 23 As shown. When the retraction is complete and the built-in lead screw nut 50 slides into the head optical shaft section 341, the transmission fails again. At this time, the transmission belt 40 continues to rotate and reset until the end of the slide groove 472 contacts the stop bar 411 of the lock 41, completing a complete working cycle.

[0036] In this embodiment, the material support platform 49 is a conveyor belt, which is installed inside the U-shaped telescopic frame 30. The conveyor belt is powered by the conveyor belt drive motor 51 at the bottom.

[0037] The working process of this invention is as follows: First, by synchronously controlling the lifting device 2 and the moving base 6, the entire system moves along the track to the target work area. Then, the electric chain hoist 20 is operated to lift the lifting platform 5 loaded with materials (such as cables, pipes, etc.) to the designated layer via the lifting guide wheels 10 along the directional guide rail 4. Next, the telescopic mechanism is activated, allowing the cantilever support beam 31 and the material carrying platform 49 to extend sequentially and dock with the platform. Finally, the conveyor belt, which serves as the material carrying platform 49, is activated to continuously and efficiently transport the materials into the platform, completing the transport. After the operation is completed, the reverse operation can reset the equipment or move it to the next work point.

[0038] Of course, the above description is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the embodiments of the present invention. The present invention is also not limited to the above examples, and all equivalent changes and improvements made by those skilled in the art within the scope of the present invention should fall within the patent coverage of the present invention.

Claims

1. A rail-mounted lifting crane for the construction of petrochemical steel structure platforms, characterized in that, include: Guide carriage (1), which is installed on the frame structure at the top of the steel structure platform; The lifting device (2) travels along the length of the guide slide (1), and the boom of the lifting device (2) extends from the edge of the platform. An electric chain hoist (20) for lifting is provided on the boom. The movable base (6) is installed on the ground guide rail (7) below the steel structure platform. A pair of parallel directional guide rails (4) are vertically arranged on the movable base (6). The ground guide rail (7) is laid along the length of the steel structure platform and is parallel to the guide slide (1). The lifting platform (5) slides and rises along the directional guide rail (4). The lifting platform (5) is connected to the electric chain hoist (20) via slings (8). The lifting platform (5) includes a fixed frame (29) and a telescopic frame (30). The telescopic frame (30) is provided with a material carrying platform (49). The telescopic frame (30) is slidably installed on the fixed frame (29) and can extend towards the steel structure platform. The telescopic frame (30) is also provided with a cantilever support beam (31) that extends outwards before it. And, a coupling frame (3) for connecting the boom of the lifting device (2) to the top of the directional guide rail (4); The extension and retraction of the cantilever support beam (31) and the telescopic frame (30) are driven by the same set of drivers, which includes a telescopic drive motor (39) and its driven spindle; the spindle simultaneously drives the belt drive system for extending the telescopic frame (30) and the screw drive system for extending the cantilever support beam (31); The belt drive system includes a drive belt (40), and the telescopic frame (30) is connected to the drive belt (40) via a buckle (41). The drive belt (40) is provided with a groove (47) for the stop bar (411) on the buckle (41) to slide within a predetermined stroke, thereby realizing the timing control that the telescopic frame (30) only begins to extend after the cantilever support beam (31) has extended to the position. The lead screw drive system includes a lead screw (34) and a built-in lead screw nut (50) that is threadedly engaged with the lead screw (34); the two ends of the lead screw (34) are respectively provided with a head optical shaft section (341) and a tail optical shaft section (342) without threads; when the built-in lead screw nut (50) is driven to either optical shaft section, its threaded transmission with the lead screw (34) fails, and an elastic element is provided at the optical shaft section to push the built-in lead screw nut (50) back to the threaded section of the lead screw (34) to restore transmission when the motor reverses.

2. The rail-mounted lifting crane for the construction of petrochemical steel structure platforms according to claim 1, characterized in that, The guide carriage (1) is fixed to the top frame structure of the steel structure platform by a number of U-bolts (11) and ear plates (12).

3. The rail-mounted lifting crane for the construction of petrochemical steel structure platforms according to claim 1, characterized in that, The material carrier platform (49) is a conveyor belt, which is driven by an independent conveyor belt drive motor (51).

4. A rail-mounted lifting crane for the construction of a petrochemical steel structure platform according to claim 1, characterized in that, The guide carriage (1) includes a supporting bottom rail (13) and a supporting top rail (14). The main body (15) of the lifting device (2) is located between the two. It has a lifting drive wheel (16) at the bottom, a top longitudinal anti-torsion guide wheel (19) at the top, and a bottom transverse anti-torsion guide wheel (17) and a top transverse anti-torsion guide wheel (18) on the side to resist the torsional load generated by the boom.

5. A rail-mounted lifting crane for the construction of a petrochemical steel structure platform according to claim 1, characterized in that, The coupling frame (3) includes a horizontal frame (21), a vertical frame (25), and a fixed seat (28); the connection between the vertical frame (25) and the horizontal frame (21) allows relative movement on the horizontal plane; the connection between the fixed seat (28) and the vertical frame (25) allows relative movement in the vertical direction to compensate for installation errors and dynamic deformation of the system during travel.

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