Ice transport device for large bridge components
The modular design of the bridge component ice transport device, which employs spherical contact and elastomer design, solves the problems of high ice surface bearing capacity requirements and limited applicable scenarios for transporting large bridge components on ice, achieving safe and stable ice transport and reducing engineering costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ROAD & BRIDGE INT CO LTD
- Filing Date
- 2025-09-19
- Publication Date
- 2026-07-31
AI Technical Summary
Existing methods for transporting large bridge components on ice have drawbacks, including high requirements for the ice's load-bearing capacity, easy damage to the ice and bridge components, and limited applicability.
The modularly designed transport device includes a platform, support system, sliding system, anti-tipping system, and traction cable. Utilizing spherical contact and elastomer design, it achieves uniform load distribution and prevents lateral overturning, and is driven to slide on the ice surface by the traction cable.
It enables safe and stable transportation of bridge components, reduces the risk of ice surface damage, improves transportation efficiency, and the device is easy to assemble and disassemble, thus reducing project costs.
Smart Images
Figure CN224577359U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of transportation technology, specifically to an ice transport device for large bridge components. Background Technology
[0002] In my country's high-latitude regions, rivers, lakes, and other bodies of water naturally freeze over in winter, forming thick and solid natural ice sheets. These ice sheets not only provide convenient natural venues for temporary ice transport of supplies and ice and snow sports and entertainment activities, but also have special value for the construction of bridges over water in cold regions: if the ice sheets can be rationally developed into transport channels for large bridge components, the component transfer cycle can be significantly shortened to accelerate the construction progress, while saving the construction costs of temporary transport roads, significantly improving the overall economic efficiency of the project. This represents a highly promising direction for resource utilization in bridge construction in cold regions.
[0003] However, current ice transport technology for large bridge components still has significant shortcomings. Existing mainstream transport methods mainly fall into two categories, both facing unavoidable limitations: Firstly, specialized transport vehicles are used. The core problem with this method is the sheer weight of the transport vehicles, which can typically reach over 30% of the weight of the bridge components (such as beams) to be transported. The combined weight of the components and the vehicle results in a total load on the ice surface far exceeding its conventional bearing capacity, making the transport plan impossible in most cases due to insufficient ice surface load-bearing capacity. Simultaneously, the contact area between the vehicle wheels and the ice surface is extremely small, concentrating the load on a localized area, easily leading to localized damage such as ice surface cracking and collapse. Furthermore, when the width or length of the bridge components exceeds the size limitations of conventional transport vehicles, the vehicles cannot be adapted to the component's shape, further restricting the applicability of this method.
[0004] Secondly, a sliding block towing method is used for transportation. This method involves placing rigid blocks at the bottom of bridge components and using external traction to move the components across the ice surface. However, the structural characteristics of rigid blocks introduce several drawbacks: in uneven ice environments, the bottom of the blocks is prone to localized detachment, leading to uneven stress distribution and subsequent localized stress concentration on the ice surface, causing damage. Furthermore, the lack of a flexible fit between the rigid blocks and the bridge components results in mutual constraints on deformation between the components and blocks, leading to disordered and uneven force transmission paths. This easily causes cracks and deformations in both the bridge components and the blocks themselves due to localized stress concentration. Additionally, the sliding mechanism between the blocks and the ice surface limits the flexibility of component movement and turning, restricting transportation paths to straight lines or large-radius curves, making it difficult to adapt to the complex transportation needs of construction sites.
[0005] In summary, existing ice transportation methods generally suffer from problems such as high requirements for ice surface bearing capacity, easy damage to ice surface and bridge components, and limited applicable scenarios. Utility Model Content
[0006] The purpose of this utility model is to provide an ice transport device for large bridge components, which meets the needs of transporting large components on ice, and features light weight, low requirements for ice cover load-bearing capacity, and is easy to transport, install and disassemble.
[0007] To achieve the above objectives, this application proposes an ice transport device for large bridge components, comprising: The platform, as the main load-bearing structure of the transportation device, is used to provide a stable supporting foundation for the entire device; The support system, assembled on the top surface of the platform, is used to directly support the bridge components and transfer the load of the bridge components to the platform; The sliding system, placed between the platform bottom and the ice surface, supports the platform and enables the platform to slide the bridge components on the ice surface. The anti-tipping system is installed on both sides of the support system to prevent lateral overturning during the transportation of bridge components; The towing cable, with one end fixed to the platform and the other end used to connect to external towing equipment, provides power for the entire transport device to slide on the ice by applying horizontal tension to the platform.
[0008] In one embodiment, the support system includes: The upper seat plate has a convex spherical bottom surface and a horizontal top surface, which is used to support bridge components and connect to the bottom of the bridge components. The lower seat plate has a concave spherical top surface and a horizontal bottom surface, which fits tightly and is fixedly connected to the top surface of the platform. The spherical gasket is a curved sheet of polytetrafluoroethylene of uniform thickness, which is fitted between the convex spherical surface of the upper seat plate and the concave spherical surface of the lower seat plate to form a sliding contact fit.
[0009] In one embodiment, the sliding system includes: The sliding disc, placed on the ice surface, is a steel disc structure with a horizontal bottom in the middle and an upward curve around the edges, used to form a stable contact with the ice surface; The steel cylinder is a circular steel pipe fitting that is mounted on the slide plate, with its lower end fixedly connected to the top surface of the slide plate. The elastomer is a cylindrical rubber block that is fitted and installed inside the steel cylinder. Its bottom is in close contact with the top surface of the slide plate, and its top is in close contact with the bottom surface of the platform to achieve elastic load-bearing. The stop blocks are fixedly connected to the bottom of the platform and are evenly distributed along the circumference of the steel cylinder to limit the relative spatial position between the steel cylinder and the platform.
[0010] In one embodiment, the anti-tilt system includes: The pad is a cubic rubber block that is placed on the top surface of the platform below both sides of the upper seat plate. Its bottom surface is fixedly connected to the platform by adhesive. The sliding plate is a flat sheet of polytetrafluoroethylene of uniform thickness, which is fixed to the top surface of the pad by adhesive to form a sliding fit with the upper seat plate.
[0011] In one embodiment, when transporting bridge components on ice, platforms, support systems, sliding systems, and anti-tipping systems are configured at both ends of the bridge components to achieve balanced support and force distribution at both ends of the components; the traction cable is fixedly connected only to the platform at the front end of the bridge component in the direction of travel.
[0012] In one embodiment, in the direction perpendicular to the travel of the bridge components, at least two sliding systems are arranged at the bottom of a single platform, and each sliding system is symmetrically distributed along the transverse centerline of the bottom of the platform to ensure balanced transverse force; in the direction parallel to the travel of the bridge components, one or more rows of sliding systems are arranged at the bottom of a single platform according to the single bearing capacity of the sliding system and the actual bearing limit requirements of the ice surface to achieve uniform load distribution.
[0013] In one embodiment, the mating contact surfaces of the convex spherical surface of the upper seat plate, the two side surfaces of the spherical gasket, and the concave spherical surface of the lower seat plate are kept in close contact; and a lubricant is applied between the convex spherical surface of the upper seat plate and the surface of the spherical gasket to reduce the frictional resistance when the two rotate relative to each other.
[0014] In one embodiment, the bottom surface of the sliding disc is polished to ensure a smooth and flat surface, thereby reducing the coefficient of friction between it and the ice surface and reducing the sliding resistance of the device; the vertical height of the steel cylinder is less than the vertical height of the elastic body, ensuring that after the elastic body is compressed and deformed under load during transportation, the bottom surface of the platform will not come into contact with the top surface of the steel cylinder, thus avoiding damage to the components from rigid collisions.
[0015] In one embodiment, a 5-10mm gap is reserved between the top surface of the sliding plate and the bottom surface of the upper seat plate. This gap does not cause contact when the bridge component is in a vertical state. When the bridge component tilts slightly to the side due to the unevenness of the ice surface, the two form a contact fit to limit the tilting range and prevent the bridge component from overturning. The bottom surface of the upper seat plate is polished to a smooth state, and the upper surface of the sliding plate is coated with lubricant to reduce the coefficient of friction that causes relative sliding when the two come into contact, and to avoid local damage to the component due to excessive frictional resistance.
[0016] In one embodiment, the outer diameter of the elastic body is smaller than the inner diameter of the steel cylinder, and the vertical centerline of the elastic body and the steel cylinder are aligned. The annular gap between them is larger than the horizontal gap between the stop and the outer wall of the steel cylinder, ensuring that the elastic body has sufficient room to move when it is compressed and deformed. The vertical height of the stop is greater than the vertical distance from the top of the steel cylinder to the bottom of the platform, so as to effectively limit the steel cylinder and prevent vertical misalignment between the platform and the steel cylinder.
[0017] Compared with the prior art, the above technical solutions adopted by this utility model have the following advantages: 1. This device adopts a modular design, with a simple overall structure and easy processing and manufacturing of each component, effectively controlling the manufacturing cost; and each component is lightweight, which facilitates transportation, on-site assembly and disassembly, and can be reused multiple times, further reducing the overall project cost.
[0018] 2. For bridge components of different weights and ice surface conditions with different load-bearing capacities, this device can flexibly adjust the number of sliding systems to evenly distribute the self-weight load of bridge components to a larger area of ice surface. It has strong adaptability and can meet diverse ice transportation needs.
[0019] 3. Compared to the tires of traditional transport vehicles, the contact area between the sliding disc and the ice surface in this device is significantly increased, which can greatly reduce the pressure per unit area of the ice surface, prevent the ice surface from cracking and being damaged due to excessive local load, and ensure the safety of transport operations.
[0020] 4. The elastomer in the sliding system of this device is made of rubber, which has a large vertical elastic compression deformation capacity. Even under uneven ice conditions, the adaptive deformation of the elastomer can ensure that each sliding system is subjected to uniform force, effectively avoiding the problems of device damage and ice surface damage caused by uneven force in traditional rigid sliding devices.
[0021] 5. The support system of this device adopts a spherical contact structure, forming a rotatable hinge structure, which can realize the rotation of the bridge components and the platform in any direction: on the one hand, it can make the two rotate relative to each other in the horizontal plane to meet the turning requirements when the beam transport path is curved; on the other hand, it can make the two rotate relative to each other in the vertical plane to adapt to the free rigid body displacement of the bridge components under the condition of uneven ice surface, and avoid the generation of forced stress between the components and the device. Attached Figure Description
[0022] Figure 1 A side elevation diagram of an ice transport device for a large bridge component; Figure 2 A front elevation view of an ice transport device for a large bridge component; Figure 3 A schematic elevation view of the support system for an ice transport device for a large bridge component; Figure 4 A schematic plan view of the sliding system of an ice transport device for a large bridge component; The numbers in the diagram are explained as follows: 1. Platform; 201. Upper seat plate; 202. Lower seat plate; 203. Spherical gasket; 301. Sliding plate; 302. Steel cylinder; 303. Elastic body; 304. Stop block; 401. Pad block; 402. Slide plate; 5. Traction cable; 6. Beam. Detailed Implementation
[0023] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.
[0024] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.
[0025] In the description of this application, it should be understood that the terms "center", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.
[0026] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0027] Please see Figure 1-4 This embodiment provides an ice transport device for large bridge components, including a platform 1, a support system, a sliding system, an anti-tipping system, and a traction cable 5. These components work together to achieve safe and stable ice transport of the bridge components 6. The specific structure is as follows: Platform 1, serving as the main load-bearing structure of the device, is fabricated by cross-welding of steel beams. During transportation, one platform 1 is installed at each end of the bridge component 6 in the direction of travel. Symmetrical support at both ends prevents deformation caused by single-point stress on the component, providing a stable foundation for the entire transportation process.
[0028] A support system, located on the top surface of platform 1, directly supports bridge component 6 and transfers loads, while also enabling multi-angle rotation between the bridge component and platform 1. This system includes an upper seat plate 201, a lower seat plate 202, and a spherical pad 203. The upper seat plate 201 has a convex spherical bottom surface and a horizontal top surface. The top surface is fixedly connected to the bottom of the bridge component 6 by bolts to ensure reliable connection. The lower seat plate 202 has a top surface designed as a concave spherical surface that matches the convex spherical surface of the upper seat plate 201, and a bottom surface that is horizontal. It is fixed to the top surface of the platform 1 by welding to ensure stable load transfer. The spherical gasket 203 is a curved PTFE sheet of uniform thickness, which is fitted between the convex spherical surface of the upper seat plate 201 and the concave spherical surface of the lower seat plate 202. PTFE material inherently possesses low friction properties, and combined with the fitting design of the convex and concave spherical surfaces, it allows for rotation in any direction between the bridge component 6 and the platform 1: satisfying the horizontal turning requirements when the beam transport path is curved, and also accommodating free rigid body displacement in the vertical plane when the ice surface is locally uneven, effectively avoiding forced stress between the component and the device.
[0029] The sliding system is arranged between the bottom surface of platform 1 and the ice surface. Each sliding system includes a sliding disc 301, a steel cylinder 302, an elastic body 303, and a stop block 304. Its core function is to support platform 1, reduce the frictional resistance of the ice surface, and achieve uniform force distribution through elastic self-adaptation. The 301 sliding disc is a steel disc with a horizontal bottom in the middle and an upward curve around the edges. The bottom surface is polished to significantly reduce the coefficient of friction with the ice surface and reduce the need for traction power. Steel cylinder 302 is a circular steel pipe, and its lower end is fixed to the top surface of slide plate 301 by welding to ensure that the two form an integrated structure. The elastic body 303 is a cylindrical rubber block placed inside the steel cylinder 302, with its bottom in close contact with the top surface of the slide plate 301 and its top in close contact with the bottom surface of the platform 1. Its height is greater than the height of the steel cylinder 302 to ensure that after the elastic body 303 is deformed under pressure, the bottom surface of the platform 1 will still not contact the top surface of the steel cylinder 302, thus avoiding rigid collision damage to the platform 1 or components; The stop block 304 is a cubic steel block that is welded to the bottom of the platform 1 and is evenly arranged around the steel cylinder 302. It can both limit the relative displacement between the steel cylinder 302 and the platform 1 and reserve sufficient space for the deformation of the elastic body 303.
[0030] The anti-tipping system, located on both sides of the support system (along the perpendicular direction of travel), is used to prevent bridge component 6 from overturning laterally due to the unevenness of the ice surface. It includes pad blocks 401 and sliding plates 402. The pad 401 is a cubic rubber block, and its bottom surface is fixed to the top surface of the platform 1 by adhesive bonding to ensure that it will not fall off under the action of lateral force; The sliding plate 402 is a flat sheet of polytetrafluoroethylene of uniform thickness, which is fixed to the top surface of the pad 401 by adhesive. A gap is reserved between the top surface of the sliding plate 402 and the bottom surface of the upper seat plate 201. During normal transportation, the two do not contact each other and do not affect the rotation function of the support system. When the bridge component 6 tilts slightly to the side, the two quickly contact each other to form a limit, preventing the tilt angle from expanding further. At the same time, the low friction characteristics of polytetrafluoroethylene can reduce frictional damage when the upper seat plate 201 contacts the sliding plate 402.
[0031] The traction cable 5 is welded and fixed at one end to the side of the platform 1 at the front end of the bridge component 6 in the direction of travel via an ear plate, and the other end is connected to the traction equipment. By applying a horizontal pulling force, the entire device is driven to slide. Only single-end traction is required to achieve smooth movement of the component, simplifying the equipment layout.
[0032] In this embodiment, a sliding system is symmetrically arranged at the bottom of each platform 1 along the vertical direction of travel; along the direction of travel, one or more rows of sliding systems are arranged according to the load requirements to ensure that the load is evenly distributed to the ice surface and to avoid excessive local pressure.
[0033] In this embodiment, the contact surfaces of the convex spherical surface of the upper seat plate 201, the spherical gasket 203, and the concave spherical surface of the lower seat plate 202 need to be tightly fitted, and lubricant is applied to the contact surface between the convex spherical surface of the upper seat plate 201 and the spherical gasket 203 to further reduce rotational friction resistance. In this embodiment, the diameter of the elastic body 303 is smaller than the inner diameter of the steel cylinder 302, their vertical center lines coincide, and the annular gap is larger than the horizontal gap between the stop block 304 and the steel cylinder 302, ensuring that the elastic body 303 does not excessively compress against the inner wall of the steel cylinder 302 when it is deformed under pressure. In this embodiment, the vertical height of the stop block 304 is greater than the distance from the top of the steel cylinder 302 to the bottom of the platform 1, ensuring that the steel cylinder 302 is effectively limited by the stop block 304 when it is vertically displaced, thus preventing the platform 1 from detaching from the sliding system.
[0034] The ice transport device for the aforementioned large bridge components is used as follows: First, clear the snow and floating ice from the ice surface, mark the placement position of the slide disc 301 according to the design points, and adjust the level of the slide disc 301; weld and fix the steel cylinder 302 to the slide disc 301; finally, put the elastic body 303 into the steel cylinder 302, ensuring that the bottom of the elastic body 303 is completely in close contact with the top surface of the slide disc 301, with no suspended areas.
[0035] The platform 1 with the bottom stop 304 welded to it is slowly hoisted above the elastic body 303, so that the bottom surface of the platform 1 is in close contact with the top surface of the elastic body 303. The position of the platform 1 is adjusted to ensure that the horizontal gap between the stop 304 and the outer wall of the steel cylinder 302 is uniform. Then, the installation position of the pad 401 is marked on the top surface of the platform 1, adhesive is applied and the pad 401 is pasted. After curing, the slide plate 402 is pasted on the top surface of the pad 401. After pasting, pressure is applied to ensure that the slide plate 402 is firmly fixed.
[0036] Weld the lower seat plate 202 to the center of the top surface of the platform 1; place a spherical gasket 203 on the concave spherical surface of the lower seat plate 202 and apply lubricant, then place the upper seat plate 201 with the convex spherical surface facing down on the gasket, adjust the position of the upper seat plate 201 so that the contact surfaces of the three are tightly fitted; finally, use a crane to hoist the bridge component 6 to the top surface of the upper seat plate 201, align the bolt holes and tighten the bolts to complete the component fixing.
[0037] Connect one end of the traction cable 5 to the ear plate of the front platform 1, and fix the other end to the traction device. Before starting the traction device, check all the connection parts. After confirming that there are no errors, slowly apply the pulling force and drive the device to slide on the ice surface.
[0038] This embodiment, through the aforementioned device, achieves safe ice transport of bridge component 6, with no ice surface cracking and no component deformation throughout the transport process, and has the following significant effects: The elastomer 303 of the sliding system can adapt to uneven ice surfaces, effectively protecting the ice surface and the equipment. The spherical contact structure of the support system allows for flexible component steering, enabling smooth steering on curved transport sections without the need to adjust the overall position of the device, thus improving transport efficiency. The large-area contact design of the sliding plate 301 ensures that the actual pressure on the ice surface is lower than the ice surface's bearing capacity, meeting safety requirements; at the same time, the components of the device can be disassembled and reused, reducing transportation costs.
[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.
Claims
1. An ice transport device for large bridge components, characterized in that, include: The platform serves to provide the supporting infrastructure; The support system, assembled on the top surface of the platform, is used to directly support the bridge components and transfer the load of the bridge components to the platform; The sliding system, placed between the platform bottom and the ice surface, supports the platform and enables the platform to slide the bridge components on the ice surface. The anti-tipping system is installed on both sides of the support system to prevent lateral overturning during the transportation of bridge components; The towing cable, with one end fixed to the platform and the other end used to connect to external towing equipment, provides power for the entire transport device to slide on the ice by applying horizontal tension to the platform.
2. The ice transport device for large bridge components according to claim 1, characterized in that, The support system includes: The upper seat plate has a convex spherical bottom surface and a horizontal top surface, which is used to support bridge components and connect to the bottom of the bridge components. The lower seat plate has a concave spherical top surface and a horizontal bottom surface, which fits tightly and is fixedly connected to the top surface of the platform. The spherical gasket is a curved sheet of polytetrafluoroethylene of uniform thickness, which is fitted between the convex spherical surface of the upper seat plate and the concave spherical surface of the lower seat plate to form a sliding contact fit.
3. The ice transport device for large bridge components according to claim 1, characterized in that, The sliding system includes: The sliding disc, placed on the ice surface, is a steel disc structure with a horizontal bottom in the middle and an upward curve around the edges; The steel cylinder is a circular steel pipe fitting that is mounted on the slide plate, with its lower end fixedly connected to the top surface of the slide plate. The elastomer is a cylindrical rubber block that is fitted and installed inside the steel cylinder. Its bottom is in close contact with the top surface of the slide plate, and its top is in close contact with the bottom surface of the platform to achieve elastic load-bearing. The stop blocks are fixedly connected to the bottom of the platform and are evenly distributed along the circumference of the steel cylinder to limit the relative spatial position between the steel cylinder and the platform.
4. The ice transport device for large bridge components according to claim 2, characterized in that, The anti-tilt system includes: The pad is a cubic rubber block that is placed on the top surface of the platform below both sides of the upper seat plate. Its bottom surface is fixedly connected to the platform by adhesive. The sliding plate is a flat sheet of polytetrafluoroethylene of uniform thickness, which is fixed to the top surface of the pad by adhesive to form a sliding fit with the upper seat plate.
5. The ice transport device for large bridge components according to claim 1, characterized in that, When transporting bridge components on ice, platforms, support systems, sliding systems, and anti-tipping systems are configured at both ends of the bridge components to achieve balanced support and force distribution at both ends of the components; the traction cable is only fixedly connected to the platform at the front end of the bridge component in the direction of travel.
6. The ice transport device for large bridge components according to claim 1, characterized in that, In the direction perpendicular to the travel of the bridge components, at least two sliding systems are arranged at the bottom of a single platform, and each sliding system is symmetrically distributed along the transverse centerline of the bottom of the platform; in the direction parallel to the travel of the bridge components, one or more rows of sliding systems are arranged at the bottom of a single platform.
7. The ice transport device for large bridge components according to claim 2, characterized in that, The mating contact surfaces of the upper seat plate's convex spherical surface, the two side surfaces of the spherical gasket, and the lower seat plate's concave spherical surface are kept in close contact; and lubricant is applied between the convex spherical surface of the upper seat plate and the spherical gasket's contact surface.
8. The ice transport device for large bridge components according to claim 3, characterized in that, The bottom surface of the slide is smooth and flat; the vertical height of the steel cylinder is less than the vertical height of the elastic body, ensuring that even after the elastic body is compressed and deformed under load during transportation, the bottom surface of the platform will not come into contact with the top surface of the steel cylinder.
9. The ice transport device for large bridge components according to claim 4, characterized in that, A 5-10mm gap is reserved between the top surface of the slide plate and the bottom surface of the upper seat plate, and this gap does not cause contact when the bridge components are kept vertical; the bottom surface of the upper seat plate is smooth, and the upper surface of the slide plate is coated with lubricant.
10. The ice transport device for large bridge components according to claim 3, characterized in that, The outer diameter of the elastic body is smaller than the inner diameter of the steel cylinder, and the vertical center line of the elastic body and the steel cylinder are aligned. The size of the annular gap formed between the two is larger than the size of the horizontal gap between the stop and the outer wall of the steel cylinder. The vertical height of the stop is greater than the vertical distance from the top of the steel cylinder to the bottom of the platform.