Energy-absorbing large-buffer type anti-falling beam device and construction method thereof

Abstract

The present application relates to a kind of energy-absorbing large buffer type beam falling prevention device and its construction method.The existing beam falling prevention device has the problems of single function, inconstant energy absorption, and the non-return problem of energy absorption device.The beam falling prevention device of the present application is longitudinally arranged between two rows of T-beams, and two anchoring baffles longitudinally arranged in front and back are respectively mounted to the inner side of the bottom of the two T-beams;It includes an energy-absorbing end assembly, an anchor cable and a buffer end assembly, the energy-absorbing end assembly is connected to the buffer end assembly through the anchor cable, and the energy-absorbing end assembly and the buffer end assembly are respectively fixed to the two anchoring baffles longitudinally arranged in front and back.The present application is a multifunctional beam falling prevention device with buffer energy-absorbing function, which can continuously and smoothly absorb instantaneous impact energy, making the beam falling prevention device have more stable energy-absorbing performance;At the same time, the beam falling prevention device of the present application has a non-return device, which is not easy to be ejected from the back after breaking to cause unpredictable harm, and is safer and more reliable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bridge construction, in particular to an energy-absorbing large-buffer type anti-falling beam device and a construction method thereof. BACKGROUND

[0002] A bridge beam body is supported on the top of a pier by a support, and some anti-falling beam measures are generally taken to prevent the beam surface from being displaced and falling off the support, so as to ensure the safety of the structure.

[0003] The commonly used anti-falling beam device is a steel strand cable type anti-falling beam device, which has various forms, including a simple structure type and a buffer energy-absorbing type, but all have some deficiencies. The device structure of the simple structure type does not have a buffer energy-absorbing function, and when a special situation such as an earthquake occurs, the beam body will produce an instantaneous impact, and the anti-falling beam is easy to break and fail. The device structure of the buffer energy-absorbing type mostly uses wedge-shaped extrusion deformation to absorb energy, and the energy absorption is not constant, but increases as it goes back, and when an instantaneous impact occurs, the energy-absorbing cylinder is easy to burst and damage. In addition, the energy-absorbing device does not have a check device, and the anti-falling beam is easy to be ejected from the back and cause unpredictable harm after breaking.

[0004] Therefore, it is necessary to propose new measures to overcome the above-mentioned defects. SUMMARY

[0005] The purpose of the present application is to provide an energy-absorbing large-buffer type anti-falling beam device and a construction method thereof, so as to solve the problems of single function, non-constant energy absorption, and non-checking of the energy-absorbing device of the existing steel strand cable type anti-falling beam device.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] The energy-absorbing large-buffer type anti-falling beam device is longitudinally arranged between two rows of T-beams, and two anchor baffles arranged longitudinally in front and back are respectively mounted to the inner sides of the bottoms of the T-beams on both sides.

[0008] The anti-falling beam device comprises an energy-absorbing end assembly, an anchor cable, and a buffer end assembly, the energy-absorbing end assembly is connected with the buffer end assembly through the anchor cable, and the energy-absorbing end assembly and the buffer end assembly are respectively fixed to two anchor baffles arranged longitudinally in front and back.

[0009] Further, the inner sides of the bottoms of the T-beams are pre-provided with T-beam partitions, the T-beam partitions on the transverse two sides are oppositely arranged, and the inner sides of the transverse two ends of the anchor baffles are respectively fixed to the end faces of the longitudinal outer sides of the T-beam partitions on both sides.

[0010] Further, the energy-absorbing end assembly comprises an energy-absorbing cylinder, an energy-absorbing rod, a spring, an energy-absorbing end stop plate, a nut, and an energy-absorbing end protective cover.

[0011] The energy absorption cylinder is fixed to the longitudinal outer side of the anchoring baffle, the energy absorption end protection cover is fixed to the longitudinal outer side of the energy absorption cylinder, the energy absorption rod, the spring, the energy absorption end stop baffle and the nut are located in the energy absorption cylinder and the energy absorption end protection cover;

[0012] One end of the anchor cable passes through the anchoring baffle and is sequentially inserted into the energy absorption cylinder, the energy absorption rod, the spring and the energy absorption end stop baffle, and the end is provided with the nut;

[0013] The energy absorption rod is located in the energy absorption cylinder, and the two ends of the spring are respectively limited in the energy absorption end stop baffle and the energy absorption rod.

[0014] Further, the inner diameter of the energy absorption cylinder near one end of the energy absorption end stop baffle is greater than the inner diameter of the energy absorption cylinder near one end of the anchoring baffle;

[0015] At the position of the change of the inner diameter in the energy absorption cylinder, the movement of the energy absorption rod to the side of the anchoring baffle is limited.

[0016] Further, the energy absorption end protection cover gradually decreases longitudinally outward from the energy absorption cylinder, and the movement of the energy absorption end stop baffle longitudinally outward is limited.

[0017] Further, a steel baffle is further arranged between the outer side of the anchoring baffle and the energy absorption cylinder.

[0018] Further, a radial hole is arranged on the rod wall of the energy absorption rod, and a check device is arranged in the radial hole;

[0019] The check device comprises a check column and a reset spring, and the reset spring is located radially outward of the check column;

[0020] The radially outer end of the check column has an enlarged head, and the radially inner end of the radial hole has a reduced orifice.

[0021] Further, the buffer end assembly comprises a buffer, a tower spring, a buffer end stop baffle, a nut and a buffer end protection cover;

[0022] The buffer end protection cover is fixed to the longitudinal outer side of the anchoring baffle, and the buffer, the tower spring and the buffer end stop baffle are located in the buffer end protection cover;

[0023] The other end of the anchor cable passes through the anchoring baffle and is sequentially inserted into the buffer, the tower spring and the buffer end stop baffle, and the end is provided with the nut.

[0024] Further, the buffer end protection cover is gradually reduced from the anchoring baffle, and movement of the buffer end stop baffle in the buffer end protection cover is limited in the opposite side of the anchoring baffle.

[0025] In another aspect, a construction method of the energy-absorbing and large-buffer type anti-falling beam device is provided, and the construction method comprises:

[0026] The anchoring baffle is installed on the T-beam diaphragm, and two anchoring baffles are installed longitudinally and front and back.

[0027] One end of the anchor cable is passed through one anchoring baffle, and the energy-absorbing end assembly is installed; the other end of the anchor cable is passed through the other anchoring baffle, and the buffer end assembly is installed.

[0028] When the T-beam moves, one end of the anchor cable of the energy-absorbing end assembly moves to the opposite side of the anchoring baffle, the spring plays an energy-absorbing role, and the tower-shaped spring plays a buffering role.

[0029] When one end of the anchor cable continues to move to the outside of the check device, the reset spring is elongated, the reset column is pushed to the reduced orifice of the radial hole and exposed, the energy-absorbing rod is clamped, and a check role is played.

[0030] Compared with the prior art, the energy-absorbing and large-buffer type anti-falling beam device has the following beneficial effects:

[0031] The energy-absorbing and large-buffer type anti-falling beam device and the construction method thereof are multifunctional anti-falling beam devices, have a buffering and energy-absorbing function, can continuously and smoothly absorb instantaneous impact energy, and make the anti-falling beam device have more stable energy-absorbing performance. Meanwhile, the anti-falling beam device has a check device, is not easy to be ejected from the back after breaking to cause unpredictable harm, is safer, and is more reliable. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings of other embodiments according to these drawings without any creative effort.

[0033] Figure 1 is the elevation view of the present application.

[0034] Figure 2 is the perspective view of the present application (without the energy-absorbing end assembly).

[0035] Figure 3 is the plan view of the present application.

[0036] Figure 4 is the enlarged view of the check device of the present application.

[0037] Figures are identified as:

[0038] 1-T beam, 2-anchoring baffle, 3-T beam partition, 4-fall protection device;

[0039] 41-energy absorption end protection cover, 42-nut, 43-energy absorption end stop plate, 44-spring, 45-check device, 46-energy absorption rod, 47-energy absorption cylinder, 48-steel baffle, 49-cable, 410-bumper, 411-tower spring, 412-bumper end stop plate, 413-bumper end protection cover. DETAILED DESCRIPTION

[0040] For the purpose of promoting the understanding and facilitating appreciation of the present application, the application will be described in conjunction with the related drawings in which preferred embodiments of the application are shown. This application may, however, be carried out in many different forms and should not be construed as limited to the embodiments set forth in this disclosure. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the application to those skilled in the art.

[0041] In the description of the present application, it needs to be understood that the terms "longitudinal", "transverse", "front", "back", "left", "right", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0042] In the description of the present application, it needs to be understood that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "setting" and the like should be understood broadly, for example, it can be fixedly connected, set, or detachably connected, set, or integrally connected, set. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0043] It should also be noted that although the order of the steps is involved in the method description, in some cases, the order can be performed in a different order from here, and should not be understood as a limitation on the order of the steps.

[0044] In the detailed description, the direction of the line, i.e. the direction of the cable 49, is defined as the longitudinal direction, the direction perpendicular to it is defined as the transverse direction, one side of the energy absorption end assembly is defined as the front, and the other side of the energy absorption end assembly is defined as the back.

[0045] As Figures 1-3The application provides a large energy-absorbing and buffering type anti-falling beam device, which is a non-destructive after-loading type device, can be installed on a bridge that has been constructed or is in operation, can continuously and smoothly absorb instantaneous impact energy, and has a non-return safety function.

[0046] As Figure 1 and Figure 2 The bridge comprises two rows of T-beams 1 arranged longitudinally symmetrically, and a T-beam partition plate 3 is arranged at the inner bottom of each T-beam 1 and is constructed integrally with the T-beam 1 when the T-beam 1 is prefabricated or cast in situ. Each T-beam 1 on the transverse two sides has a T-beam partition plate 3, and the T-beam partition plates 3 on the two sides are arranged transversely opposite to each other. The anti-falling beam device 4 of the application is longitudinally arranged between the two rows of T-beams 1 and is mainly installed by means of four T-beam partition plates 3 and two anchor stop plates 2. The two anchor stop plates 2 are longitudinally arranged front and back, and the front side anchor stop plate 2 is fixed to the front end face of the front group of T-beam partition plates 3 on the transverse two sides, respectively, and the back side anchor stop plate 2 is fixed to the back end face of the back group of T-beam partition plates 3 on the transverse two sides, respectively. Based on the four T-beam partition plates 3 on the transverse left and right sides and the two anchor stop plates 2 on the longitudinal front and back sides, the anti-falling beam device 4 can be longitudinally installed to the inner bottom of the T-beams 1 on the two sides.

[0047] Specifically, the anti-falling beam device 4 of the application comprises an energy-absorbing end assembly, an anchor cable 49 and a buffering end assembly, the energy-absorbing end assembly is connected to the buffering end assembly through the anchor cable 49, and the energy-absorbing end assembly and the buffering end assembly are longitudinally arranged front and back, respectively. The energy-absorbing end assembly and the buffering end assembly are fixed to the two anchor stop plates 2 arranged longitudinally front and back, respectively. The energy-absorbing end assembly is arranged on one side, and the buffering end assembly is arranged on the other side, which can effectively increase the buffering stroke.

[0048] 1. Energy-absorbing end assembly

[0049] The energy-absorbing end assembly mainly plays an energy-absorbing role and comprises an energy-absorbing cylinder 47, an energy-absorbing rod 46, a spring 44, an energy-absorbing end stop plate 43, a nut 42 and an energy-absorbing end protective cover 41.

[0050] As Figure 3 The energy-absorbing cylinder 47 is fixed to the longitudinal outer side of the anchor stop plate 2, the energy-absorbing end protective cover 41 is fixed to the longitudinal outer side of the energy-absorbing cylinder 47, and the energy-absorbing rod 46, the spring 44, the energy-absorbing end stop plate 43 and the nut 42 are located in the energy-absorbing cylinder 47 and the energy-absorbing end protective cover 41. One end of the anchor cable 49 penetrates through the anchor stop plate 2 and is sequentially inserted into the energy-absorbing cylinder 47, the energy-absorbing rod 46, the spring 44 and the energy-absorbing end stop plate 43, and the end is provided with the nut 42. The energy-absorbing rod 46 is located in the energy-absorbing cylinder 47, and the two ends of the spring 44 are limited in the energy-absorbing end stop plate 43 and the energy-absorbing rod 46, respectively.

[0051] The inner diameter of the energy absorption cylinder 47 near the energy absorption end stop plate 43 is larger than the inner diameter of the energy absorption cylinder 47 near the anchoring stop plate 2. Therefore, the movement of the energy absorption rod 46 to the side of the anchoring stop plate 2 is limited at the position of the change in the inner diameter of the energy absorption cylinder 47. In addition, the energy absorption end protection cover 41 gradually narrows longitudinally outward, and the movement of the energy absorption end stop plate 43 longitudinally outward is limited. When the beam surface is displaced due to an earthquake, the distance between the two T-beams 1 in front and back becomes smaller, the anchor cable 49 pushes the energy absorption rod 46 to move forward (to the left) in the energy absorption cylinder 47, the energy absorption end stop plate 43 is clamped in the narrowed section of the energy absorption end protection cover 41, the nut 42 moves forward and is separated from the energy absorption end stop plate 43, and the spring 44 is compressed and shrinks, thereby playing the role of energy absorption. Figure 3

[0052] A steel stop plate 48 is further provided between the outer side of the anchoring stop plate 2 and the energy absorption cylinder 47. After the energy absorption cylinder is installed, the steel stop plate 48, the energy absorption cylinder, and the anchoring stop plate 2 are welded and fixed, thereby fixing the energy absorption cylinder. In addition, when the energy absorption cylinder is subjected to instantaneous impact, the force is dispersed and transmitted to the anchoring stop plate 2 through the steel stop plate 48, thereby avoiding local deformation and cracking of the anchoring stop plate 2.

[0053] The energy absorption end assembly further includes a check device 45, as shown in Figure 4 A radial hole is provided on the rod wall of the energy absorption rod 46, and the check device 45 is arranged in the radial hole. The check device 45 includes a check column and a reset spring, and the reset spring is located radially outward of the check column. The radially outer end of the check column has an enlarged head, and the radially inner end of the radial hole has a narrowed aperture. When the check column moves to the narrowed aperture, the enlarged head will eventually be clamped in the narrowed aperture and cannot be separated from the radial hole. When the energy absorption rod 46 continues to move forward in the energy absorption cylinder 47, the energy absorption rod 46 exceeds the check device 45 and is located to the left of the check device 45, the outer wall of the energy absorption rod 46 no longer contacts the check column, the reset spring is elongated, and the check column is pushed radially inward. The check column is exposed in the energy absorption cylinder 47 and is clamped on the right side of the energy absorption rod 46, and cannot continue to move, thereby playing the role of preventing rebound.

[0054] 2. Buffer end assembly

[0055] The buffer end assembly mainly plays the role of buffering, and includes a buffer 410, a tower spring 411, a buffer end stop plate 412, a nut 42, and a buffer end protection cover 413.

[0056] As shown in Figure 3 The buffer end protection cover 413 is fixed to the longitudinal outer side of the anchoring stop plate 2, and the buffer 410, the tower spring 411, and the buffer end stop plate 412 are located in the buffer end protection cover 413. The other end of the anchor cable 49 passes through the anchoring stop plate 2 and is sequentially inserted into the buffer 410, the tower spring 411, and the buffer end stop plate 412, and the end is provided with the nut 42. ​

[0057] The buffer end protection cover 413 gradually shrinks outward from the anchor baffle 2, and the buffer end stop plate 412 is restricted from moving inside the buffer end protection cover 413 toward the anchor baffle 2. When an earthquake causes the beam surface to shift, the distance between the front and rear T-beams 1 decreases, the anchor cable 49 moves forward, and the nut 42 forces the buffer end stop plate 412 to move toward the anchor baffle 2. The conical spring 411 is compressed, and together with the energy-absorbing end assembly, it provides a buffering effect.

[0058] The construction method of the above-mentioned energy-absorbing and large-buffer type anti-falling beam device specifically includes:

[0059] S1: Clean both sides and cross section of the T-beam partition 3, install anchor baffles 2 on the T-beam partition 3, and install two in the longitudinal direction.

[0060] S2: Pass one end of the anchor cable 49 through one anchor baffle 2 and install the energy absorbing end assembly. Pass the other end of the anchor cable 49 through another anchor baffle 2 and install the buffer end assembly.

[0061] S3: When the T-beam 1 moves, one end of the anchor cable 49 where the energy absorbing end assembly is installed moves to the side opposite to the anchor baffle 2, the spring 44 plays an energy absorbing role, and the tower spring 411 plays a buffering role.

[0062] S4: When one end of the anchor cable 49 continues to move to the outside of the anti-return device 45, the reset spring stretches, pushing the reset column toward the narrowing opening of the radial hole and exposing it to the outside, thereby clamping the energy absorbing rod 46 and playing a non-return role.

[0063] Some existing bridges are not designed to install anti-falling beam devices in advance, and no anti-falling beam installation facilities are reserved. Later, they need to be installed. Generally, a support plate is used for connection. The support plate is fixed to the beam body by expansion screws, and the anti-falling beam is connected to the support plate by fork ears. This type of support plate connection requires drilling holes in the beam body, which will cause certain damage to the beam body. In addition, the construction is not convenient and the efficiency is not high. The present invention presets a T-beam partition 3 on the T-beam 1, which can be directly installed by the anchor baffle 2. The anchor baffle 2 and the T-beam partition 3 are naturally buckled and connected, without causing any damage to the beam body, thus achieving lossless installation. Specifically, two horizontal baffles are provided on the back of the anchor baffle 2 (the contact surface with the T-beam partition 3). During installation, the T-beam partition 3 is just embedded between the two horizontal baffles. This installation method does not damage the beam body and can be installed later. That is, for projects that did not originally design an anti-falling beam, this method can be used to install the device later.

[0064] In other embodiments, the number of anti-falling beam devices 4 of the present invention may not be unique, such as Figure 1 You can set two, upper and lower, to double the energy-absorbing and buffering effect. Of course, you can also increase the number of settings according to actual needs.

[0065] In summary, the present application utilizes the existing conditions of T-beam, and can be non-destructive after loading without damaging the beam body. It can absorb the large impact load kinetic energy of the beam body during the earthquake, and can continuously and smoothly absorb the instantaneous impact energy, so that the anti-falling beam device has more stable energy absorption performance. It has a non-return device to prevent rebound, and the energy absorption range is controllable, which is safer. Radial extrusion energy absorption is used, compared with the wedge-shaped energy absorption method, the device has smaller shape, stronger installation space adaptability and lower cost. The overall structure is simple, and has the advantages of long service life, strong durability and low maintenance cost.

[0066] The above application of specific examples to the present application is only used to help understand the present application and does not limit the present application. For those skilled in the art to which the present application belongs, according to the idea of the present application, a number of simple deductions, deformations or substitutions can be made.

Claims

1. The energy-absorbing and large-buffer type anti-falling beam device is characterized in that: The anti-falling beam device (4) is longitudinally arranged between two rows of T-beams (1), and is respectively mounted to the inner side of the bottom of the T-beams (1) on both sides through two anchor baffles (2) arranged longitudinally in front and back; The anti-falling beam device (4) comprises an energy-absorbing end assembly, an anchor cable (49) and a buffer end assembly, the energy-absorbing end assembly is connected with the buffer end assembly through the anchor cable (49), and the energy-absorbing end assembly and the buffer end assembly are respectively fixed to two anchor baffles (2) arranged longitudinally in front and back; The energy-absorbing end assembly comprises an energy-absorbing cylinder (47), an energy-absorbing rod (46), a spring (44), an energy-absorbing end stop plate (43), a nut (42) and an energy-absorbing end protective cover (41); the energy-absorbing cylinder (47) is fixed to the longitudinal outer side of the anchor baffle (2), the energy-absorbing end protective cover (41) is fixed to the longitudinal outer side of the energy-absorbing cylinder (47), the energy-absorbing rod (46), the spring (44), the energy-absorbing end stop plate (43) and the nut (42) are located in the energy-absorbing cylinder (47) and the energy-absorbing end protective cover (41); one end of the anchor cable (49) passes through the anchor baffle (2) and is sequentially inserted into the energy-absorbing cylinder (47), the energy-absorbing rod (46), the spring (44) and the energy-absorbing end stop plate (43), and the end is provided with the nut (42); the energy-absorbing rod (46) is located in the energy-absorbing cylinder (47), and the two ends of the spring (44) are respectively limited to the energy-absorbing end stop plate (43) and the energy-absorbing rod (46); The inner diameter of the energy-absorbing cylinder (47) near one end of the energy-absorbing end stop plate (43) is greater than the inner diameter of the energy-absorbing cylinder (47) near one end of the anchor baffle (2); at the position of the change of the inner diameter in the energy-absorbing cylinder (47), the movement of the energy-absorbing rod (46) to one side of the anchor baffle (2) is limited; A radial hole is arranged on the rod wall of the energy-absorbing rod (46), and a check device (45) is arranged in the radial hole; the check device (45) comprises a check column and a reset spring, and the reset spring is located on the radial outer side of the check column; the radial outer end of the check column has an enlarged head, and the radial inner end of the radial hole has a reduced aperture.

2. The energy-absorbing and large-buffer type anti-falling beam device according to claim 1 is characterized in that: The inner side of the bottom of the T-beam (1) is provided with a T-beam partition plate (3), and the T-beam partition plates (3) on the transverse two sides are oppositely arranged, and the inner sides of the transverse two ends of the anchor baffle (2) are respectively fixed to the end faces on the longitudinal outer sides of the T-beam partition plates (3) on both sides.

3. The energy-absorbing and large-buffer type anti-falling beam device according to claim 2 is characterized in that: The energy-absorbing end protective cover (41) gradually decreases longitudinally outward from the energy-absorbing cylinder (47), and the movement of the energy-absorbing end stop plate (43) longitudinally outward is limited.

4. The energy-absorbing and large-buffer type anti-falling beam device according to claim 3 is characterized in that: A steel baffle (48) is further arranged between the outer side of the anchor baffle (2) and the energy-absorbing cylinder (47).

5. The energy-absorbing and large-buffer type anti-falling beam device according to claim 4, wherein: the buffer end assembly comprises a buffer (410), a tower spring (411), a buffer end stop plate (412), a nut (42) and a buffer end protection cover (413); the buffer end protection cover (413) is fixed to the longitudinal outer side of the anchoring stop plate (2), and the buffer (410), the tower spring (411) and the buffer end stop plate (412) are located in the buffer end protection cover (413); the other end of the anchor cable (49) passes through the anchoring stop plate (2) and is sequentially inserted into the buffer (410), the tower spring (411) and the buffer end stop plate (412), and the end is provided with the nut (42).

6. The energy-absorbing and large-buffer type anti-falling beam device according to claim 5, wherein: the buffer end protection cover (413) gradually narrows from the anchoring stop plate (2) outward, and the movement of the buffer end stop plate (412) in the buffer end protection cover (413) in the direction opposite to the anchoring stop plate (2) is limited.

7. The construction method of the energy-absorbing and large-buffer type anti-falling beam device according to claim 6, wherein: the construction method comprises: installing the anchoring stop plate (2) on the T-beam partition plate (3), and installing two anchoring stop plates (2) longitudinally in front and back; passing one end of the anchor cable (49) through one anchoring stop plate (2) and installing the energy-absorbing end assembly, and passing the other end of the anchor cable (49) through the other anchoring stop plate (2) and installing the buffer end assembly; when the T-beam (1) moves, the one end of the anchor cable (49) installed with the energy-absorbing end assembly moves to the side opposite to the anchoring stop plate (2), the spring (44) plays an energy-absorbing role, and the tower spring (411) plays a buffering role; when the one end of the anchor cable (49) continues to move to the outside of the check device (45), the reset spring is elongated, pushes the reset column to the reduced aperture of the radial hole and is exposed, clamps the energy-absorbing rod (46), and plays a check role. ​ ​ ​ ​ ​ ​ ​ ​ ​

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