shock absorber

Abstract

The present application provides a shock absorbing device, comprising a first seat, a limiting structure, a second seat, a plurality of shear pins and a plurality of elastic sleeves. The limiting structure is fixedly mounted on the outer periphery of the first seat. The second seat is mounted on the limiting structure. A plurality of shear pins are provided with notches; the plurality of shear pins are plugged into the limiting structure and the second seat, and are configured to be sheared under a preset impact load. A plurality of elastic sleeves are axially through-arranged and respectively sleeved on the plurality of shear pins. The shock absorbing device provided in the present application wraps an elastic sleeve around the outer periphery of the shear pin, which can reduce the impact load transmitted to the first seat when the impact load does not reach a preset value, so as to reduce the shock of the building structure mounted on the first seat, and help to improve the shock absorbing effect. When the impact load reaches the preset value, the relative displacement between the first seat and the second seat can be reduced, and the fracture process is relatively gentle, so that the first seat can rotate normally relative to the second seat, which greatly improves the shock absorbing effect.

Description

Technical Field

[0001] The invention belongs to the technical field of building facilities, and particularly relates to a shock absorbing device. Background Art

[0002] In recent years, in order to improve the seismic performance of building structures, a large number of shock-absorbing devices have been used to extend the natural vibration period of the building structure, reduce the impact of the earthquake transmitted to the building structure, and effectively protect the building structure. In the relevant technical field, shock-absorbing devices are mostly composed of two base bodies and shear pins, wherein the shear pins are inserted into the two base bodies. When there is a climate with strong impact loads such as earthquakes and hurricanes, the shear pins are sheared off, and the two base bodies can rotate relative to each other to buffer the impact load. However, in actual application, due to the strong impact load, the shear pins are prone to brittle fracture, resulting in a large relative displacement of the two base bodies, which ultimately leads to a poor shock-absorbing effect of the shock-absorbing device. Summary of the Invention

[0003] The purpose of the embodiments of the present application is to provide a shock absorbing device to solve the technical problem in the prior art that the shear pins are prone to brittle fracture, resulting in poor shock absorbing effect of the shock absorbing device.

[0004] To achieve the above-mentioned purpose, the technical solution adopted in this application is to provide a shock absorbing device, comprising:

[0005] First seat;

[0006] a limiting structure, fixedly mounted on the outer periphery of the first seat;

[0007] A second seat body is installed on the limiting structure;

[0008] a plurality of shear pins with notches formed thereon; the plurality of shear pins are all plugged into the limiting structure and the second seat body, and are configured to be sheared under a preset impact load;

[0009] A plurality of elastic sleeves are provided through the axial direction and are respectively sleeved on the plurality of shear pins.

[0010] Optionally, the cross section of the notch perpendicular to the radial direction is set to be V-shaped; wherein the V-shaped vertex and the connection surface between the limiting structure and the second seat body are located in the same plane.

[0011] Optionally, the inner circumference of the elastic sleeve has an elastic boss, and the elastic boss is located in the notch.

[0012] Optionally, the limiting structure is provided with a plurality of first pin holes; the second seat is provided with a plurality of second pin holes, and the plurality of second pin holes and the plurality of first pin holes are arranged in a one-to-one correspondence.

[0013] Optionally, the first pin hole and the second pin hole are both configured as tapered holes; the elastic sleeve includes a first tapered sleeve and a second tapered sleeve, the first tapered sleeve is installed in the first pin hole, the second tapered sleeve is installed in the second pin hole, and is connected to the first tapered sleeve.

[0014] Optionally, a first inclined surface is provided on the outer circumference of the first conical sleeve, and the first inclined surface is gradually reduced in the axial direction from an end away from the second conical sleeve toward an end close to the second conical sleeve; a second inclined surface is provided on the outer circumference of the second conical sleeve, and the second inclined surface is gradually reduced in the axial direction from an end away from the first conical sleeve toward an end close to the first conical sleeve.

[0015] Optionally, a countersunk hole is provided on the side of the limiting structure facing away from the second seat body, and the countersunk hole is connected to the first pin hole; the shear pin includes a first pin rod, a second pin rod and a pin head, the first pin rod is inserted into the first pin hole, the second pin rod is connected to the end of the first pin rod away from the countersunk hole, the pin head is connected to the end of the first pin rod away from the second pin rod, and is limited in the countersunk hole, and is also configured to be able to limit the first pin rod axially through the countersunk hole; wherein, the notch is located between the first pin rod and the second pin rod.

[0016] Optionally, the outer peripheral side of the elastic sleeve has a plurality of protrusions.

[0017] Optionally, a first arc-shaped cavity is formed on the side of the first seat body facing the second seat body; a second arc-shaped cavity is formed on the side of the second seat body facing the first seat body; the shock absorbing device also includes a spherical cap, which is located in a closed space formed by the first arc-shaped cavity and the second arc-shaped cavity.

[0018] Optionally, the shock absorbing device further includes a first buffer pad and a second buffer pad, wherein the first buffer pad is arranged between the first seat body and the spherical crown, and the second buffer pad is arranged between the second seat body and the spherical crown.

[0019] The beneficial effects of the shock absorbing device provided by this application are:

[0020] The shock-absorbing device provided in the embodiment of the present application, by wrapping an elastic sleeve around the outer periphery of the shear pin, can buffer the impact load transmitted from the second base to the shear pin when the impact load does not reach a preset value, thereby reducing the impact load transmitted to the first base, thereby reducing the shock of the building structure mounted to the first base, and helping to improve the shock absorption effect. Furthermore, when the impact load reaches the preset value, it can simultaneously buffer the impact load and the impact generated by the brittle fracture of the shear pin, thereby reducing the relative displacement of the shear pin during brittle fracture, and further reducing the relative displacement between the first base and the second base. The fracture process is relatively gentle, allowing the first base to rotate normally relative to the second base, greatly improving the shock absorption effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0022] Figure 1 A first cross-sectional view of the shock absorbing device provided in Example 1 of the present application;

[0023] Figure 2 for Figure 1 A partial enlarged view of point A in the middle;

[0024] Figure 3 A second cross-sectional view of the shock absorbing device provided in Example 1 of the present application;

[0025] Figure 4 for Figure 3 A partial enlarged view of point B in the middle;

[0026] Figure 5 A cross-sectional view of the shock absorbing device provided in Example 2 of the present application;

[0027] Figure 6 This is a cross-sectional view of the shock absorbing device provided in Example 4 of the present application.

[0028] Among them, the reference numerals in the figures are:

[0029] 100. First seat; 110. First arc-shaped cavity;

[0030] 200, limiting structure; 210, first pin hole; 220, second pin hole; 230, countersunk hole;

[0031] 300, second seat; 310, second arc-shaped cavity;

[0032] 400, shear pin; 410, notch; 420, first pin rod; 430, second pin rod; 440, pin head;

[0033] 500, elastic sleeve; 510, elastic boss; 520, first tapered sleeve; 530, second tapered sleeve; 540, first inclined surface; 550, second inclined surface;

[0034] 600, ball crown;

[0035] 700, first cushion;

[0036] 800, second cushion;

[0037] 900. Anchor rod. DETAILED DESCRIPTION

[0038] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0039] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0040] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and 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, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0041] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0042] Based on this, the present invention provides a shock absorbing device, which can prevent the shear pin from brittle fracture by arranging an elastic sleeve on the outer periphery of the shear pin, thereby helping to improve the shock absorbing effect.

[0043] Example 1

[0044] like Figures 1 to 4 As shown, an embodiment of the present application provides a shock absorbing device, comprising a first seat body 100, a limiting structure 200, a second seat body 300, a plurality of shear pins 400 and a plurality of elastic sleeves 500. The limiting structure 200 is fixedly mounted on the outer periphery of the first seat body 100. The second seat body 300 is mounted on the limiting structure 200. Notches 410 are provided on the plurality of shear pins 400; the plurality of shear pins 400 are all plugged into the limiting structure 200 and the second seat body 300, and are configured to be sheared under a preset impact load. The plurality of elastic sleeves 500 are arranged to pass through in the axial direction and are respectively sleeved on the plurality of shear pins 400.

[0045] It should be noted that the axial direction above and below refers to the bidirectional direction of the central axis defined by the geometric structure of the elastic sleeve 500, specifically Figure 1 The X-axis shown in .

[0046] It should also be noted that in this embodiment, multiple anchor rods 900 are fixedly mounted on both the side of the first base 100 facing away from the second base 300 and the side of the second base 300 facing away from the first base 100. In actual applications, the shock-absorbing device is installed between a load-bearing structure and a structure to be shock-absorbed. The load-bearing structure typically refers to a building structure directly connected to the ground, i.e., a building structure that preferentially receives impact loads. In this embodiment, the multiple anchor rods 900 on the side of the first base 100 facing away from the second base 300 are used to connect to the structure to be shock-absorbed, while the multiple anchor rods 900 on the side of the second base 300 facing away from the first base 100 are used to connect to the load-bearing structure. Of course, depending on actual application requirements, the multiple anchor rods 900 on the side of the first base 100 facing away from the second base 300 can also be used to connect to the load-bearing structure, and the multiple anchor rods 900 on the side of the second base 300 facing away from the first base 100 can also be used to connect to the structure to be shock-absorbed.

[0047] Specifically, the shear pin 400 has a notch 410 so that the shear pin 400 can be sheared under a preset impact load. When the impact load does not reach the preset value, the impact load is transmitted to the second base body 300 through the anchor rod 900 on the side of the second base body 300 facing away from the first base body 100. The second base body 300 transmits the impact load to the elastic sleeve 500, which can buffer the impact load. When the impact load reaches the preset value, the shear pin 400 is sheared. After the shear pin 400 breaks, it will cause the elastic sleeve 500 to undergo elastic deformation. At this time, the elastic deformation of the elastic sleeve 500 can simultaneously buffer the impact load and the impact caused by the brittle fracture of the shear pin 400.

[0048] The shock-absorbing device provided in this application, by wrapping an elastic sleeve 500 around the outer periphery of the shear pin 400, can buffer the impact load transmitted from the second base body 300 to the shear pin 400 when the impact load does not reach a preset value, thereby reducing the impact load transmitted to the first base body 100, thereby reducing the shock of the building structure mounted on the first base body 100 and helping to improve the shock absorption effect. Furthermore, when the impact load reaches a preset value, it can simultaneously buffer the impact load and the impact generated when the shear pin 400 undergoes brittle fracture, thereby reducing the displacement rate of the shear pin 400 when brittle fracture occurs, and further reducing the displacement rate between the first base body 100 and the second base body 300. The fracture process is relatively gentle, allowing the first base body 100 to rotate normally relative to the second base body 300, greatly improving the shock absorption effect.

[0049] In one embodiment of the present application, see Figures 1 to 4 The cross section of the notch 410 perpendicular to the radial direction is configured to be V-shaped, wherein the V-shaped vertex and the connection surfaces between the limiting structure 200 and the second base body 300 are located in the same plane.

[0050] It should be noted here that the radial directions above and below refer to directions perpendicular to the axial direction.

[0051] Such a configuration, using the notch 410, can cause the shear pin 400 to be sheared off from the notch 410 when the impact load reaches a preset value. Since the cross section of the notch 410 perpendicular to the radial direction is set to be V-shaped, it is convenient for the shear pin 400 to be sheared off. In addition, since the V-shaped vertex and the connection surface between the limiting structure 200 and the second seat body 300 are located in the same plane, after the shear pin 400 is sheared off, the shear surface of the shear pin 400 and the connection surface between the limiting structure 200 and the second seat body 300 are located in the same plane, so that the first seat body 100 and the second seat body 300 can rotate normally, thereby preventing the local structure after the shear pin 400 is sheared from interfering with the relative rotation of the first seat body 100 and the second seat body 300, causing the impact load to far exceed the preset value, and further preventing the local structure after the shear pin 400 is broken from brittle fracture again, which helps to further improve the shock absorption effect.

[0052] In one embodiment of this application, please refer to Figures 1 to 4 The limiting structure 200 is provided with a plurality of first pin holes 210. The second base 300 is provided with a plurality of second pin holes 220, and the plurality of second pin holes 220 are arranged in a one-to-one correspondence with the plurality of first pin holes 210.

[0053] With this arrangement, the shear pin 400 can be inserted into the limiting structure 200 using the first pin hole 210 and can be detachably connected to the limiting structure 200. The shear pin 400 can be inserted into the second base 300 using the second small hole and can be detachably connected to the second base 300.

[0054] In one embodiment of the present application, see Figures 1 to 4 The limiting structure 200 has a countersunk hole 230 on the side facing away from the second base 300. The countersunk hole 230 is connected to the first pin hole 210. The shear pin 400 includes a first pin rod 420, a second pin rod 430, and a pin head 440. The first pin rod 420 is inserted into the first pin hole 210. The second pin rod 430 is connected to the end of the first pin rod 420 away from the countersunk hole 230. The pin head 440 is connected to the end of the first pin rod 420 away from the second pin rod 430 and is limited in the countersunk hole 230. The pin head 440 is also configured to limit the first pin rod 420 axially through the countersunk hole 230. The notch 410 is located between the first pin rod 420 and the second pin rod 430.

[0055] This arrangement, using the countersunk hole 230, allows for the installation of the pin head 440 and axially limits the first pin 420. This prevents the first pin 420 from axially moving toward the second pin 430 after the shear pin 400 shears, potentially causing brittle fracture of the first pin 420 between the retaining structure 200 and the second base 300, further enhancing the shock absorption effect. Furthermore, during installation, when the pin head 440 is installed in the countersunk hole 230, the first pin 420 inserts into the first pin hole 210, and the second pin 430 inserts into the second pin hole 220, facilitating installation. Furthermore, because the notch 410 is located between the first and second pins 420, 430, when the impact load reaches a predetermined value, the first and second pins 420, 430 shear and displace relative to each other, thereby enabling relative rotation between the first and second bases 100, 300.

[0056] In one embodiment of the present application, see Figures 1 to 4 A first arcuate cavity 110 is defined on the side of the first base 100 facing the second base 300. A second arcuate cavity 310 is defined on the side of the second base 300 facing the first base 100. The shock-absorbing device further includes a spherical cap 600, which is located within the enclosed space formed by the first arcuate cavity 110 and the second arcuate cavity 310.

[0057] With this arrangement, after the shear pin 400 is sheared, the spherical cap 600 can slide relative to the second base 300 and the first base 100, preventing direct relative rotation between the first and second bases 100, further enhancing the shock absorption effect. The use of the first and second curved cavities 110, 310 facilitates installation of the spherical cap 600 between the first and second bases 100, 300, improving ease of use and facilitating sliding of the spherical cap 600 relative to the first and second bases 100, 300.

[0058] In one embodiment of this application, please refer to Figures 1 to 4 The shock absorbing device further includes a first buffer pad 700 and a second buffer pad 800 . The first buffer pad 700 is disposed between the first seat body 100 and the spherical crown 600 , and the second buffer pad 800 is disposed between the second seat body 300 and the spherical crown 600 .

[0059] In this configuration, the first cushion 700 prevents direct contact between the spherical cap 600 and the first seat 100, effectively protecting them when they slide relative to each other, and thus helping to extend the service life of the spherical cap 600 and the first seat 100. The second cushion 800 prevents direct contact between the spherical cap 600 and the second seat 300, effectively protecting them when they slide relative to each other, and thus helping to extend the service life of the second seat 300, and further extending the service life of the spherical cap 600.

[0060] Example 2

[0061] This embodiment is basically the same as the first embodiment, the only difference is that: Figures 1 to 5 As shown, the first pin hole 210 and the second pin hole 220 are both configured as tapered holes. The elastic sleeve 500 includes a first tapered sleeve 520 and a second tapered sleeve 530. The first tapered sleeve 520 is installed in the first pin hole 210, and the second tapered sleeve 530 is installed in the second pin hole 220 and connected to the first tapered sleeve 520. A first inclined surface 540 is defined on the outer circumference of the first tapered sleeve 520. The first inclined surface 540 gradually tapers in the axial direction from the end away from the second tapered sleeve 530 toward the end closer to the second tapered sleeve 530. A second inclined surface 550 is defined on the outer circumference of the second tapered sleeve 530. The second inclined surface 550 gradually tapers in the axial direction from the end away from the first tapered sleeve 520 toward the end closer to the first tapered sleeve 520.

[0062] Specifically, when the impact load reaches a preset value, the shear pin 400 is sheared. After the shear pin 400 is sheared, the first pin 420 and the second pin 430 move relative to each other, generating a tensile force on the first and second tapered sleeves 520 and 530. Under the tensile force, the first tapered sleeve 520 tends to move toward the second tapered sleeve 530. Because the first inclined surface 540 gradually tapers axially from the end distal to the second tapered sleeve 530 toward the end proximal to the second tapered sleeve 530, the first pin hole 210 can restrain the first tapered sleeve 520. Under the tensile force, the second tapered sleeve 530 tends to move toward the first tapered sleeve 520. Because the second inclined surface 550 gradually tapers axially from the end distal to the first tapered sleeve 520 toward the end proximal to the first tapered sleeve 520, the second pin hole 220 can restrain the second tapered sleeve 530.

[0063] In this way, the first pin hole 210 and the second pin hole 220 are both set as conical holes, and the first conical sleeve 520 and the second conical sleeve 530 are used. After the shear pin 400 is cut off, the limiting structure 200 can limit the first conical sleeve 520 through the first pin hole 210, and the second seat body 300 can limit the second conical sleeve 530 through the second pin hole 220. This can prevent the first conical sleeve 520 from quickly escaping from the first pin hole 210 as much as possible, resulting in a large relative displacement rate between the limiting structure 200 and the second seat body 300. It can also prevent the second conical sleeve 530 from quickly escaping from the second pin hole 220 as much as possible, resulting in an excessively large relative displacement rate between the limiting structure 200 and the second seat body 300, making the fracture process more moderate and further improving the shock absorption effect.

[0064] Example 3

[0065] This embodiment is basically the same as the first embodiment, the only difference is that: Figures 1 to 4 As shown, the outer peripheral side of the elastic sleeve 500 has a plurality of protrusions (not shown in the figure).

[0066] By providing multiple protrusions on the outer circumference of the elastic sleeve 500, the surface roughness of the elastic sleeve 500 can be increased, thereby increasing the friction between the elastic sleeve 500 and the retaining structure 200, and also increasing the friction between the elastic sleeve 500 and the second base 300. When the shear pin 400 is sheared, it prevents the elastic sleeve 500 from quickly dislodging from the first pin hole 210 or the second pin hole 220, thereby preventing the relative displacement rate between the retaining structure 200 and the second base 300 from being too large, making the fracture process more gradual and further improving the shock absorption effect.

[0067] Example 4

[0068] This embodiment is basically the same as the first embodiment, the only difference is that: Figures 1 to 6 As shown, the inner circumference of the elastic sleeve 500 has an elastic boss 510 , and the elastic boss 510 is located in the notch 410 .

[0069] In this configuration, by providing an elastic boss 510 on the inner circumference of the elastic sleeve 500, the elastic boss 510 abuts against the notch 410. When the impact load does not reach a preset value, the elastic boss 510 can buffer the impact load acting on the notch 410. Furthermore, when the impact load reaches a preset value and the shear pin 400 is sheared, the elastic boss 510 can roughly limit the position of the first pin 420 and the second pin 430, thereby minimizing axial movement of the first pin 420 and the second pin 430. This can prevent the first pin 420 from brittle fracture when inserted between the limiting structure 200 and the second base 300, and can also prevent the second pin 430 from brittle fracture when inserted between the limiting structure 200 and the second base 300, thereby further improving the shock absorption effect.

[0070] The one or more embodiments of this application are intended to encompass all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this application should be included in the scope of protection of this application.

Claims

1. A shock absorbing device, characterized in that: include: first seat body (100); A limiting structure (200) fixedly mounted on the outer periphery of the first seat (100); A second seat body (300) is mounted on the limiting structure (200); a plurality of shear pins (400) with notches (410) formed thereon; the plurality of shear pins (400) are all plugged into the limiting structure (200) and the second seat (300), and are configured to be sheared under a preset impact load; A plurality of elastic sleeves (500) are provided through the axial direction and are respectively sleeved on the plurality of shear pins (400); The limiting structure (200) is provided with a plurality of first pin holes (210); the second seat (300) is provided with a plurality of second pin holes (220), and the plurality of second pin holes (220) and the plurality of first pin holes (210) are arranged in a one-to-one correspondence; The first pin hole (210) and the second pin hole (220) are both configured as tapered holes; the elastic sleeve (500) comprises a first tapered sleeve (520) and a second tapered sleeve (530), wherein the first tapered sleeve (520) is installed in the first pin hole (210), and the second tapered sleeve (530) is installed in the second pin hole (220) and connected to the first tapered sleeve (520).

2. The shock absorbing device according to claim 1, wherein: The cross section of the notch (410) perpendicular to the radial direction is arranged in a V-shape; wherein the V-shaped vertex and the connection surface between the limiting structure (200) and the second seat body (300) are located in the same plane.

3. The shock absorbing device according to claim 1, wherein: The inner peripheral side of the elastic sleeve (500) is provided with an elastic boss (510), and the elastic boss (510) is located in the notch (410).

4. The shock absorbing device according to claim 1, wherein: A first inclined surface (540) is provided on the outer peripheral side of the first conical sleeve (520), and the first inclined surface (540) is gradually reduced in the axial direction from an end away from the second conical sleeve (530) toward an end close to the second conical sleeve (530); a second inclined surface (550) is provided on the outer peripheral side of the second conical sleeve (530), and the second inclined surface (550) is gradually reduced in the axial direction from an end away from the first conical sleeve (520) toward an end close to the first conical sleeve (520).

5. The shock absorbing device according to claim 1, wherein: The limiting structure (200) is provided with a countersunk hole (230) on a side facing away from the second seat body (300), and the countersunk hole (230) is connected to the first pin hole (210); the shear pin (400) includes a first pin rod (420), a second pin rod (430) and a pin head (440), the first pin rod (420) is inserted into the first pin hole (210), the second pin rod (430) is connected to an end of the first pin rod (420) away from the countersunk hole (230), the pin head (440) is connected to an end of the first pin rod (420) away from the second pin rod (430), and is limited in the countersunk hole (230), and is also configured to be able to limit the first pin rod (420) along the axial direction through the countersunk hole (230); wherein the notch (410) is located between the first pin rod (420) and the second pin rod (430).

6. The shock absorbing device according to claim 1, wherein: The outer peripheral side of the elastic sleeve (500) has a plurality of protrusions.

7. The shock absorbing device according to claim 1, wherein: A first arc-shaped cavity (110) is provided on a side of the first seat body (100) facing the second seat body (300); a second arc-shaped cavity (310) is provided on a side of the second seat body (300) facing the first seat body (100); the shock-absorbing device further comprises a spherical cap (600), and the spherical cap (600) is located in a closed space enclosed by the first arc-shaped cavity (110) and the second arc-shaped cavity (310).

8. The shock absorbing device according to claim 7, wherein: The shock absorbing device further comprises a first buffer pad (700) and a second buffer pad (800), wherein the first buffer pad (700) is arranged between the first seat body (100) and the spherical cap (600), and the second buffer pad (800) is arranged between the second seat body (300) and the spherical cap (600).

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