Double reverse four-bar linkage boom system of crane and crane

Abstract

This application relates to the technical field of four-bar linkage gantry cranes, specifically to a double-reverse four-bar linkage boom system and a crane. The double-reverse four-bar linkage boom system of this application includes: a main boom; a trunk-like beam; the head of the main boom is hinged to the trunk-like beam and close to its tail; a swing arm, one end of which is hinged to the head of the trunk-like beam; and a tie rod assembly located on the side of the trunk-like beam facing the main boom and between the main boom and the swing arm. The tie rod assembly includes a first tie rod, a second tie rod, and a connecting rod. One end of the first tie rod is hinged to the main boom, one end of the connecting rod is hinged to the trunk-like beam, one end of the second tie rod is hinged to the end of the swing arm away from the trunk-like beam, and the other ends of the first and second tie rods are respectively hinged to the end of the connecting rod away from the trunk-like beam. This application reduces the swaying caused by wind vibration of the tie rod and eliminates the risk of fatigue fracture that may result from long-term wind vibration of the tie rod, thereby avoiding related safety accidents.

Description

Technical Field

[0001] This application relates to the field of crane technology, specifically to a double-reverse four-bar linkage system for cranes and the crane itself. Background Technology

[0002] In traditional four-bar linkage gantry cranes, the pulleys at the head of the crane are arranged in a straight line, suitable for grab and hook loading and unloading operations. However, in container handling, this cannot solve problems such as uneven container loading, which seriously affects the efficiency of container loading and unloading. Therefore, a reverse four-bar linkage gantry crane was developed based on the traditional four-bar linkage gantry crane to better suit the working conditions of container operations and improve the flexibility of gantry crane container handling.

[0003] However, in conventional gantry cranes, the tie rods in the reverse four-bar linkage have a large slenderness ratio, which often causes vertical vibration due to wind vibration during actual operation. This not only affects the operation, but also leads to the failure of the linkage due to long-term vibration fatigue, resulting in serious production accidents. Summary of the Invention

[0004] The purpose of this application is to provide a double-reverse four-bar linkage boom system for a crane and the crane itself, which reduces the swaying caused by wind vibration of the tie rod, eliminates the risk of fatigue fracture that may be caused by long-term wind vibration of the tie rod, and avoids the occurrence of related safety accidents.

[0005] To solve at least one of the above-mentioned technical problems, this application adopts the following technical solution:

[0006] According to a first aspect of this application, a double-reverse four-bar linkage system for a crane is provided, comprising: a main boom; the main boom being part of a gantry crane, a trunk-like structure, the head of the main boom being hinged to the trunk-like structure and close to the tail of the trunk-like structure; a swing arm, one end of which is hinged to the head of the trunk-like structure; a tie rod assembly located on the side of the trunk-like structure facing the main boom and between the main boom and the swing arm; the tie rod assembly includes a first tie rod, a second tie rod, and a connecting rod, one end of the first tie rod being hinged to the main boom, one end of the connecting rod being hinged to the trunk-like structure, one end of the second tie rod being hinged to the end of the swing arm away from the trunk-like structure, and the other ends of the first tie rod and the other ends of the second tie rod being respectively hinged to the end of the connecting rod away from the trunk-like structure.

[0007] In one possible implementation of the first aspect described above, the pull rod assembly further includes: a first connecting shaft, wherein the end of the connecting rod away from the elephant trunk beam is hinged to the first pull rod and the second pull rod via the first connecting shaft.

[0008] In one possible implementation of the first aspect described above, the lengths of the first and second pull rods are equal.

[0009] In one possible implementation of the first aspect described above, the angle between the centerline of the first tie rod along its length and the centerline of the second tie rod along its length is no greater than 1 degree.

[0010] In one possible implementation of the first aspect described above, the first tie rod includes: two first connecting rods arranged side by side, one end of which is hinged to the head of the main boom and the other end of which is hinged to a connecting rod, the head of the main boom being located between the two first connecting rods; a first fixing rod arranged between the two first connecting rods and connected to the two first connecting rods respectively; preferably, the first connecting rods and the first fixing rods are arranged perpendicular to each other; each of the two ends of each first connecting rod is provided with a first ear plate, and each first ear plate is provided with a first hinge hole.

[0011] In one possible implementation of the first aspect described above, the second tie rod includes: two second connecting rods arranged side by side, one end of which is hinged to the swing arm and the other end of which is hinged to the connecting rod; and a second fixed rod disposed between the two second connecting rods and connected to the two second tie rods respectively.

[0012] In one possible implementation of the first aspect described above, each second link includes a first segment, a second segment, and a third segment connected sequentially along its length. The first segment and the third segment are parallel. The end of the first segment away from the second segment is hinged to a connecting rod, and the end of the third segment away from the second segment is hinged to a swing rod. The two first segments are parallel, the two third segments are parallel, the distance between the two first segments is greater than the distance between the two third segments, and the distance between the two second segments decreases from the first segment to the third segment.

[0013] In one possible implementation of the first aspect described above, two third links are arranged side by side, one end of which is hinged to the elephant trunk bridge and the other end of which is hinged to the first tie rod and the second tie rod respectively; a third fixed rod is arranged between the two third links and is connected to the two third links respectively.

[0014] In one possible implementation of the first aspect described above, the head of the elephant trunk is provided with an elephant trunk pulley for the steel wire rope to pass through, and the hinge center axis of the swing arm and the elephant trunk coincides with the center axis of the elephant trunk pulley; the end of the swing arm away from the elephant trunk is provided with a swing arm pulley for the steel wire rope to pass through, and the center axis of the swing arm pulley is parallel to the center axis of the elephant trunk pulley.

[0015] According to a second aspect of this application, a crane is provided, including the double-reverse four-bar linkage boom system of the crane of the first aspect of this application.

[0016] The above-mentioned technical solution of this application has at least one of the following beneficial effects:

[0017] According to this application, a double-reverse four-bar linkage system for a crane is provided. A connecting rod is added between the boom and the first and second tie rods. One end of the first tie rod is hinged to the main boom, one end of the connecting rod is hinged to the boom, and one end of the second tie rod is hinged to the end of the swing arm away from the boom. The other ends of the first and second tie rods are respectively hinged to the ends of the connecting rods away from the boom, thus forming a double-reverse four-bar linkage structure consisting of the main boom, boom, first tie rod, second tie rod, connecting rod, and swing arm. This mechanism not only ensures translational characteristics during crane luffing but also optimizes the force transmission path and component stress distribution. Because the tie rod is divided into two segments, the length of each segment is significantly shortened compared to a conventional integral tie rod, reducing the slenderness ratio of the tie rod by approximately half. This reduction in slenderness ratio directly improves the tie rod's resistance to buckling, making it less prone to buckling deformation under compression. As a result, under the same level of wind load, the maximum bending moment borne by the tie rod of the present invention is reduced, which reduces the swaying caused by wind vibration of the tie rod and eliminates the risk of fatigue fracture that may be caused by long-term wind vibration of the tie rod. This significantly enhances the wind resistance of the present invention and significantly improves the reliability, safety and service life of the boom system under harsh working conditions. It is especially suitable for gantry crane operations in high wind environments such as ports and docks.

[0018] In addition, unless otherwise specified in the technical solution of this application, the technical solution can be implemented by conventional means in the field. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a structural schematic diagram of a double-reverse four-bar linkage boom system according to one embodiment of this application;

[0021] Figure 2 This is one embodiment of the present application. Figure 1 A magnified view of a portion of region AA in the middle;

[0022] Figure 3 This is a schematic diagram of the structure of a tie rod assembly according to one embodiment of this application;

[0023] Figure 4 This is one embodiment of the present application. Figure 3 A magnified view of a portion of the BB region;

[0024] Figure 5This is one embodiment of the present application. Figure 3 A magnified view of a portion of the CC region;

[0025] Figure 6 This is a schematic diagram of the connecting rod according to one embodiment of this application;

[0026] Figure 7 This is a schematic diagram of a double-reverse four-bar linkage system according to one embodiment of the present application, showing that the first and second tie rods have a certain included angle.

[0027] Figure 8 This is a structural schematic diagram of a double-reverse four-bar linkage boom system according to one embodiment of this application;

[0028] Figure 9 A schematic diagram of a reverse four-bar linkage boom system according to one embodiment;

[0029] Figure 10 for Figure 9 A schematic diagram of the load and bending moment of the third tie rod;

[0030] Figure 11 This is a schematic diagram showing the load and bending moment of the first and second tie rods according to one embodiment of this application;

[0031] Figure 12 This is a schematic diagram of the structure of a crane according to one embodiment of this application.

[0032] Explanation of the labels in the attached drawings:

[0033] 100. Main boom;

[0034] 200. Elephant trunk bridge;

[0035] 300, swing arm;

[0036] 400. Tie rod assembly;

[0037] 410. First tie rod; 411. First connecting rod; 412. First fixing rod; 413. First ear plate; 414. First hinge hole;

[0038] 420. Second tie rod; 421. Second connecting rod; 4211. First section; 4212. Second section; 4213. Third section; 422. Second fixing rod;

[0039] 430. Connecting rod; 431. Third connecting rod; 432. Third fixed rod;

[0040] 440. First connecting shaft;

[0041] 500. Elephant Trunk Pulley;

[0042] 600. Swing rod pulley;

[0043] 700, Third pull rod. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of 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 only some, not all, of the embodiments of this application, and are used merely to explain this application and are not intended to limit it. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0045] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "front," "rear," "vertical," "horizontal," "inner," "outer," "both ends," "both sides," "bottom," and "top," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the elements 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. In addition, the terms "first," "second," "upper-level," "lower-level," "main," and "secondary," etc., are used for descriptive purposes only and can be simply used to more clearly distinguish different components, and should not be construed as indicating or implying relative importance.

[0046] 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 fixed connections, detachable connections, or integral molding; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0047] Conventional gantry cranes have an inverse four-bar linkage boom system, such as Figure 9 As shown, the boom, third tie rod 700, swing arm, and trunk-like structure are sequentially hinged to form a reverse four-bar linkage. The third tie rod 700 has a large length-to-slenderness ratio, and in actual operation, it often vibrates vertically due to wind vibration. This not only affects the operation but also causes the linkage to break due to long-term vibration fatigue, resulting in serious production accidents.

[0048] refer to Figure 1 , Figure 2 and Figure 8The diagram schematically illustrates a double-reverse four-bar linkage system for a crane according to an embodiment of this application. The double-reverse four-bar linkage system of this application includes: a main boom 100, a trunk beam 200, a tie rod assembly 400, and a swing arm 300. The bottom end of the main boom 100 is connected to the crane's turntable. The head of the main boom 100 is hinged to the trunk beam 200 and close to its tail. One end of the swing arm 300 is hinged to the head of the trunk beam 200. The tie rod assembly 400 is located on the side of the trunk beam 200 facing the main boom 100 and is positioned between the main boom 100 and the swing arm 300.

[0049] The tie rod assembly 400 includes a first tie rod 410, a second tie rod 420, and a connecting rod 430. One end of the first tie rod 410 is hinged to the main boom 100, one end of the connecting rod 430 is hinged to the trunk beam 200, and one end of the second tie rod 420 is hinged to the end of the swing arm 300 away from the trunk beam 200. The other ends of the first tie rod 410 and the second tie rod 420 are respectively hinged to the ends of the connecting rod 430 away from the trunk beam 200. The main boom 100, trunk beam 200, first tie rod 410, second tie rod 420, connecting rod 430, and swing arm 300 form a double-inverse four-bar linkage structure. That is, the main boom 100, trunk beam 200, connecting rod 430, and first tie rod 410 form an inverse four-bar linkage mechanism, and the trunk beam 200, connecting rod 430, second tie rod 420, and swing arm 300 also form an inverse four-bar linkage mechanism.

[0050] Therefore, the double-reverse four-bar linkage boom system of the crane in this application adopts a double-reverse four-bar linkage mechanism, which directly reduces the slenderness ratio of the first tie rod 410 and the second tie rod 420. The reduction in the slenderness ratio directly improves the tie rod's resistance to instability, making it less prone to buckling deformation under compression. Furthermore, under the same level of wind load, the maximum bending moment borne by the tie rod is reduced, decreasing the swaying caused by wind vibration and eliminating the risk of fatigue fracture that may result from long-term wind vibration. The wind resistance is significantly enhanced, significantly improving reliability, safety, and service life, making it particularly suitable for gantry crane operations in high-wind outdoor environments such as ports and docks.

[0051] In some embodiments, reference Figure 3 , Figure 5As shown, the tie rod assembly 400 further includes a first connecting shaft 440, with the end of the connecting rod 430 away from the elephant trunk 200 hinged to the first tie rod 410 and the second tie rod 420 via the first connecting shaft 440. On the surface of the first connecting shaft 440, the connecting rod 430 is located on the inner side, and the first tie rod 410 and the second tie rod 420 are located on the outer side. All three are mirror images of each other relative to the plane containing the midpoint of the central axis of the first connecting shaft 440. Thus, the connecting rod 430, the first tie rod 410, and the second tie rod 420 are on the same hinge axis. The connecting rod 430 only bears the weight of the tie rod and the wind vibration force generated by wind pressure on the tie rod, thereby ensuring uniform and stable force on both sides, improving mechanical performance to ensure the wind vibration resistance of the tie rod assembly 400 and extend its service life. In addition, the main boom 100 and the trunk beam 200 can be hinged by a second connecting shaft, the swing arm 300 and the trunk beam 200 can be hinged by a third connecting shaft, the first tie rod 410 and the main boom 100 can be hinged by a fourth connecting shaft, the connecting rod 430 and the trunk beam 200 can be hinged by a fifth connecting shaft, and the second tie rod 420 and the swing arm 300 can be hinged by a sixth connecting shaft. These details will not be elaborated further here.

[0052] In some embodiments, reference Figure 1 , Figure 7 and Figure 8 As shown, the first tie rod 410 and the second tie rod 420 are of equal length. Setting the first tie rod 410 and the second tie rod 420 to be of equal length helps to balance the stress on the entire tie rod assembly 400, enhances fatigue resistance, and extends service life.

[0053] In the lateral wind load analysis of the tie rod, since both ends of the tie rod are hinged, it can be considered as a simply supported beam with hinged ends and a uniformly distributed load q. The tie rod is supported at both ends and subjected to force in the middle. The formula for calculating the maximum bending moment that the tie rod can withstand in this case is:

[0054]

[0055] refer to Figure 10 As shown, in a conventional inverted four-bar linkage system, the length of the third tie rod 700 is set to L, and the maximum bending moment of the third tie rod 700 is set to M1. (Reference) Figure 11 As shown, the length of the first tie rod 410 or the second tie rod 420 in this application is L / 2, and the maximum bending moment is set to M2. Under the same uniformly distributed load q, substituting L and L / 2 into the formula yields:

[0056]

[0057]

[0058] Therefore, M1 = 4M2, which shows that the maximum bending moment borne by the first tie rod 410 or the second tie rod 420 is much smaller than the maximum bending moment borne by the third tie rod 700. Under the same wind force, the method of using the first tie rod 410 and the second tie rod 420 has stronger stability and less wind vibration.

[0059] In some embodiments, reference Figure 7 As shown, the angle between the centerline of the first tie rod 410 and the centerline of the second tie rod 420 along their length is α, which is no greater than 1 degree. During the crane's luffing operation, the trunk-beam pulley 500 and the swing arm pulley 600 move along an approximately horizontal line. To ensure this requirement remains constant, without changing the positioning of the tie rod assembly 400 and the swing arm 300, a suitable length for the connecting rod 430 and its appropriate positioning on the trunk-beam 200 are designed through point-finding optimization calculations. This ensures that during the crane's luffing process, the angle between the centerline of the first tie rod 410 and the centerline of the second tie rod 420 along their length is no greater than 1 degree, making the first tie rod 410 and the second tie rod 420 as close to the same axis as possible, effectively eliminating additional bending moments. When the first tie rod 410 and the second tie rod 420 are nearly coaxial, the force transmission path between them tends to be straight, and the lateral component force at the hinge point is minimized, thus significantly improving the stress condition of the tie rods and the hinge point.

[0060] In some embodiments, reference Figure 3 , Figure 4 As shown, the first tie rod 410 includes two first connecting rods 411 and a first fixed rod 412. The two first connecting rods 411 are arranged side by side, with one end of each first connecting rod 411 hinged to the head of the main boom 100 and the other end hinged to the connecting rod 430. The head of the main boom 100 is located between the two first connecting rods 411. The first fixed rod 412 is arranged between the two first connecting rods 411 and connected to each of the two first connecting rods 411. The first fixed rod 412 and the first connecting rods 411 can be perpendicular. The perpendicular arrangement can significantly improve the overall rigidity of the two side by side first connecting rods 411, effectively preventing lateral instability and torsional deformation under compression or tension. It also ensures the parallelism and force synchronization of the two connecting rods, allowing the two first connecting rods 411 to evenly distribute the load and avoid local overload caused by uneven force on a single connecting rod.

[0061] refer to Figures 3-6As shown, each of the first connecting rods 411 has a first ear plate 413 at both ends, and each first ear plate 413 has a first hinge hole 414. A bearing can be installed in the first hinge hole 414, significantly reducing the rotational friction resistance of the hinged part, avoiding direct metal-to-metal contact and wear between the hinged components, and effectively extending the service life of the hinged part. To prevent the first pull rod 410, the second pull rod 420, and the connecting rod 430 from sliding along the axial direction of the first connecting shaft 440, baffles are provided at both ends of the first connecting shaft 440 for limiting movement, and spacers are provided between the first pull rod 410, the second pull rod 420, and the connecting rod 430 for limiting movement. Each spacer is installed on the first connecting shaft 440. In addition, the two ends of the second connecting rod 421 can be provided with second ear plates, and the second ear plates are provided with second hinge holes. Bearings can be installed in the second hinge holes. The same applies to the connecting rod 430, main boom 100, elephant trunk 200 and swing rod 300, which will not be described in detail here.

[0062] In some embodiments, reference Figure 1 and Figure 3 As shown, the second tie rod 420 includes two second connecting rods 421 and a second fixed rod 422. The two second connecting rods 421 are arranged side-by-side, with one end hinged to the swing arm 300 and the other end hinged to the connecting rod 430. The second fixed rod 422 is positioned between the two second connecting rods 421 and connected to both second tie rods 420. The second tie rod 420 adopts a structure similar to the first tie rod 410, which can balance the force distribution and thus improve the overall service life.

[0063] In some embodiments, reference Figure 3 As shown, each second link 421 includes a first segment 4211, a second segment 4212, and a third segment 4213 connected sequentially along its length. The first segment 4211 and the third segment 4213 are parallel. The end of the first segment 4211 away from the second segment 4212 is hinged to the connecting rod 430, and the end of the third segment 4213 away from the second segment 4212 is hinged to the swing rod 300. The two first segments 4211 are parallel, and the two third segments 4213 are parallel. The distance between the two first segments 4211 is greater than the distance between the two third segments 4213, and the distance between the two second segments 4212 decreases from the first segment 4211 to the third segment 4213. In order to match the different widths of the connecting parts on both sides of the second tie rod 420, the distance between the two ends of the two second links 421 is required to be different. By making the first segment 4211 and the third segment 4213 parallel and the second segment 4212 inclined, the overall structural strength of the second tie rod 420 can be improved. It should be noted that in some cases, the spacing between the two first segments 4211 can be smaller than the spacing between the two third segments 4213.

[0064] In some embodiments, reference Figure 3 , Figure 5 and Figure 6 As shown, the connecting rod 430 includes two third connecting rods 431 and a third fixed rod 432. The two third connecting rods 431 are arranged side by side, with one end of each connecting rod 431 hinged to the elephant trunk beam 200, and the other end of each connecting rod 431 hinged to the first tie rod 410 and the second tie rod 420, respectively. The third fixed rod 432 is positioned between the two third connecting rods 431 and connected to each of the two connecting rods 431. The third fixed rod 432 and the third connecting rods 431 can be perpendicular to each other. This perpendicular arrangement can improve the overall rigidity of the connecting rod 430, reduce the probability of lateral instability and torsional deformation under compression or tension, and also improve the parallelism and force synchronization of the connecting rod 430.

[0065] In some embodiments, reference Figure 1 , Figure 2 As shown, the head of the elephant trunk bridge 200 is provided with an elephant trunk bridge pulley 500 for the steel wire rope to pass around, and the hinge center axis of the swing rod 300 and the elephant trunk bridge 200 coincides with the center axis of the elephant trunk bridge pulley 500; the end of the swing rod 300 away from the elephant trunk bridge 200 is provided with a swing rod pulley 600 for the steel wire rope to pass around, and the center axis of the swing rod pulley 600 is parallel to the center axis of the elephant trunk bridge pulley 500.

[0066] refer to Figure 12 As shown, a crane provided according to an embodiment of this application includes the aforementioned double-reverse four-bar linkage boom system. Other devices of the crane in this application can be existing corresponding devices, which will not be described in detail here.

[0067] Based on the various embodiments of this application described above, in the absence of explicit denial or conflict, the technical features of one embodiment may be advantageously combined with one or more other embodiments.

[0068] The above are merely some embodiments of this application, used only to illustrate the technical solution of this application, and not to limit it. It should be understood that those skilled in the art can make improvements or substitutions based on the above description without departing from the inventive concept of this application, and all such improvements and substitutions should fall within the protection scope of this application. In this case, all details can be replaced with equivalent elements, and the materials, shapes, and sizes can also be arbitrary.

Claims

1. A double-reverse four-bar linkage boom system for a crane, characterized in that, include: Main boom; The main boom has its head hinged to the trunk and close to the tail. The swing arm, one end of which is hinged to the head of the elephant trunk; The tie rod assembly is located on the side of the elephant trunk beam facing the main boom and between the main boom and the swing arm; The pull rod assembly includes a first pull rod, a second pull rod, and a connecting rod. One end of the first pull rod is hinged to the main boom, one end of the connecting rod is hinged to the elephant trunk beam, one end of the second pull rod is hinged to the end of the swing rod away from the elephant trunk beam, and the other ends of the first pull rod and the second pull rod are respectively hinged to the end of the connecting rod away from the elephant trunk beam.

2. The double-reverse four-bar linkage boom system of the crane according to claim 1, characterized in that, The tie rod assembly also includes: The first connecting shaft is used to hinge the end of the connecting rod away from the elephant trunk bridge to the first pull rod and the second pull rod via the first connecting shaft.

3. The double-reverse four-bar linkage boom system of the crane according to claim 1, characterized in that, The first pull rod and the second pull rod are of equal length.

4. The double-reverse four-bar linkage boom system of the crane according to claim 1, characterized in that, The angle between the centerline of the first tie rod along its length and the centerline of the second tie rod along its length is no greater than 1 degree.

5. The double-reverse four-bar linkage boom system of the crane according to claim 1, characterized in that, The first pull rod includes: Two first connecting rods are arranged side by side, one end of which is hinged to the head of the main boom and the other end of which is hinged to the connecting rod. The head of the main boom is located between the two first connecting rods. A first fixed rod is disposed between the two first connecting rods and is connected to the two first connecting rods respectively; Each of the first connecting rods has a first lug plate at both ends, and each of the first lug plates has a first hinge hole.

6. The double-reverse four-bar linkage boom system of the crane according to claim 1, characterized in that, The second pull rod includes: Two second connecting rods are arranged side by side, with one end of each rod hinged to the swing rod and the other end hinged to the connecting rod. The second fixing rod is disposed between the two second connecting rods and is connected to the two second tie rods respectively.

7. The double-reverse four-bar linkage boom system of the crane according to claim 6, characterized in that, Each second link includes a first segment, a second segment, and a third segment connected sequentially along its length. The first segment is parallel to the third segment. The end of the first segment away from the second segment is hinged to the connecting rod. The end of the third segment away from the second segment is hinged to the swing rod. The two first segments are parallel, the two third segments are parallel, the distance between the two first segments is greater than the distance between the two third segments, and the distance between the two second segments decreases from the first segment to the third segment.

8. The double-reverse four-bar linkage boom system of the crane according to claim 1, characterized in that, The connecting rod includes: Two third connecting rods are arranged side by side, with one end hinged to the elephant trunk beam and the other end hinged to the first tie rod and the second tie rod respectively; The third fixing rod is disposed between the two third connecting rods and is connected to the two third connecting rods respectively.

9. The double-reverse four-bar linkage boom system of the crane according to claim 1, characterized in that, The head of the elephant trunk is provided with an elephant trunk pulley for the steel wire rope to pass through, and the hinge center axis of the swing arm and the elephant trunk coincides with the center axis of the elephant trunk pulley. The end of the swing arm away from the elephant trunk beam is provided with a swing arm pulley for the steel wire rope to pass through, and the central axis of the swing arm pulley is parallel to the central axis of the elephant trunk beam pulley.

10. A crane, characterized in that, The crane includes a double-reverse four-bar linkage system as described in any one of claims 1 to 9.

Images