A flipping hoisting structure for a floating crane ship propeller and a method for installing the propeller

Abstract

The present invention discloses a turnover hoisting structure for a floating crane ship propeller and a method for installing the propeller, which relates to the technical field of shipbuilding. It includes a lifting lug group arranged on the hull block and a lifting hole group arranged on the propeller. There are five groups of lifting lug groups, and each group includes two lifting lugs. The two lifting lugs are symmetrically arranged along the longitudinal section of the propeller well axis in the ship length direction. There are three groups of lifting hole groups, and each group includes two lifting holes. Among them, the first lifting hole group and the second lifting hole group are arranged on the side of the installation flange facing the inner side of the cabin. The two lifting holes of the first lifting hole group and the two lifting holes of the second lifting hole group are located on the same circle with the center of the center hole of the installation flange as the center of the circle. A lifting rope is arranged between the lifting lug group and its corresponding lifting hole group, and the lifting rope can be tightened or loosened. By setting a reasonable hoisting structure, the controllability of each state during the turnover installation process of the propeller is realized. Finally, the propeller is adjusted to the installation position and the attitude is controllable, so as to realize the precise positioning and accurate installation of the propeller.

Description

Technical Field

[0001] The present invention relates to the technical field of shipbuilding, and particularly relates to a flipping and hoisting structure for a floating crane ship propeller and a method for installing the propeller. Background Art

[0002] A large floating crane ship is an important engineering operation ship, and a full-rotation propeller is often used as the power source. There are two common installation methods for the propeller: one is to install it using a rudder and propeller installation vehicle, and the propeller is transported to the lower part of the hull by the rudder and propeller installation vehicle for jacking installation; the other is to install it using the method of in-pit embedding. A support tooling is set in the pit, the propeller is pre-set in the pit, and after the hull section is positioned and supported at the pit position, the propeller installation is completed.

[0003] For the first method, installing using a rudder and propeller installation vehicle has the following problems: 1. The overall height of the rudder and propeller installation vehicle and the propeller is relatively high, and the required installation space is large, resulting in too high a support height for the floating crane ship section, affecting the support stability and posing a safety hazard; 2. After the operation of the hull section where the propeller is located is completed, the support height needs to be readjusted for the propeller installation operation, resulting in an extended section closing cycle and affecting the dock cycle; 3. This installation method requires the modification of the rudder and propeller installation vehicle and the setting of a special support tooling for the propeller, increasing the production cost.

[0004] For the second method, installing using the method of in-pit embedding has the following problems: 1. After the overall assembly operation of the hull section where the propeller is located is completed, the section needs to be re-lifted and its position adjusted to the pit for the propeller installation operation, resulting in an extended section closing cycle and affecting the dock cycle; 2. The cost of excavating the pit is relatively high, and the pit also occupies space. Subsequently, safety protection measures need to be added to the pit; 3. The support tooling set in the pit also needs to be specially made according to the form of the propeller, increasing the production cost. Summary of the Invention

[0005] The purpose of the present invention is to provide a flipping and hoisting structure for a floating crane ship propeller and a method for installing the propeller. By setting a reasonable hoisting structure, the controllability of each state during the flipping installation process of the propeller is realized, and finally the propeller is adjusted to the installation position with controllable attitude, so as to achieve the precise positioning and accurate installation of the propeller.

[0006] To achieve the above purpose, the technical solution of the present invention is:

[0007] A flipping hoisting structure for a floating crane ship's thruster, comprising a set of lifting lugs arranged on the hull section and a set of lifting holes arranged on the thruster; there are five sets of the lifting lug sets, each set includes two lifting lugs, and the two lifting lugs are symmetrically arranged along the longitudinal center line of the thruster well in the ship length direction; the first set of lifting lug sets and the second set of lifting lug sets are located at the bottom outside the cabin, and the connecting line of the two lifting lugs of the first set of lifting lug sets and the connecting line of the two lifting lugs of the second set of lifting lug sets are on different sides of the longitudinal center line of the thruster well. The third set of lifting lug sets, the fourth set of lifting lug sets and the fifth set of lifting lug sets are located at the top of the cabin, and the connecting line of the two lifting lugs of the third set of lifting lug sets intersects the longitudinal center line of the thruster well. The connecting line of the two lifting lugs of the fourth set of lifting lug sets and the connecting line of the two lifting lugs of the fifth set of lifting lug sets are on different sides of the longitudinal center line of the thruster well; there are three sets of the lifting hole sets, each set includes two lifting holes. The two lifting holes of the first lifting hole set and the two lifting holes of the second lifting hole set are arranged on the mounting flange and are located on the same circle with the center of the center hole of the mounting flange as the center. The two lifting holes of the first lifting hole set and the two lifting holes of the second lifting hole set are symmetrically arranged on both sides of a certain diameter of the mounting flange; the third lifting hole set is arranged on the rib plate outside the shroud of the thruster impeller, and the lifting holes of the two third lifting hole sets are symmetrically distributed along the vertical plane of the thruster impeller shaft; lifting rings are fixed in the lifting holes of the lifting hole sets; lifting ropes are arranged between the lifting lug sets and their corresponding lifting hole sets, and the lifting ropes can be tightened or loosened.

[0008] Wherein, the distance between the two lifting lugs in the lifting lug set is greater than the distance between the two lifting holes in its corresponding lifting hole set.

[0009] Wherein, any two lifting lugs can bear the weight of the entire thruster.

[0010] Wherein, the weight that any two lifting lugs can bear is 1.2 times the weight of the entire thruster.

[0011] A method for installing a thruster using the above-mentioned floating crane ship thruster flipping and hoisting structure, comprising the following steps: S1: Use a flatbed trolley to send the thruster in a lying state to a predetermined position below the hull; S2: Connect the lifting ropes at the first group of lifting lugs, the second group of lifting lugs, the third group of lifting lugs, the fourth group of lifting lugs, and the fifth group of lifting lugs to the lifting rings in the corresponding lifting hole groups. Among them, the two lifting lugs of the first group of lifting lugs are connected to the two lifting rings of the third lifting hole group one by one, the two lifting lugs of the second group of lifting lugs and the two lifting lugs of the fifth group of lifting lugs are both connected to the two lifting rings of the first lifting hole group one by one, and the two lifting lugs of the fourth group of lifting lugs are connected to the two lifting rings of the second lifting hole group one by one; S3: Tighten each lifting rope to lift the thruster off the flatbed trolley; S4: Tighten the lifting rope at the fifth group of lifting lugs and loosen the lifting rope at the first group of lifting lugs to lift the upper end of the thruster. At the same time, tighten the lifting rope at the second group of lifting lugs, and the thruster moves towards the stern side, so as to adjust the upper end of the thruster below the thruster well and gradually make the gearbox part of the thruster enter the thruster well; S5: Remove the lifting rope at the second group of lifting lugs, tighten the lifting ropes at the fourth group of lifting lugs and the fifth group of lifting lugs, and continue to loosen the lifting rope at the first group of lifting lugs to gradually adjust the thruster to an upright normal position; S6: Set two lifting ropes at the third group of lifting lugs, connect them to the first lifting hole group and the second lifting hole group respectively, and remove the lifting rope at the first group of lifting lugs; S7: Tighten the lifting ropes at the third group of lifting lugs, lift the thruster into the thruster well, and test-fit the thruster with the hull and check the clearance of the mating surface; S8: Loosen the lifting ropes at the third group of lifting lugs, the fourth group of lifting lugs, and the fifth group of lifting lugs, lower the thruster, immediately apply sealant to the installation flange surface of the thruster after coating, and then lift the thruster up immediately to ensure that the flange surface of the thruster is smoothly joined to the hull, install flat gaskets and bolts, and tighten the bolts in a diagonal order to ensure that the thruster is completely pressed, and complete the installation of the thruster.

[0012] Among them, before the thruster installation operation, simulate the installation process to determine the attitude and position of the thruster at each stage during the installation process and determine the length of the lifting rope.

[0013] Among them, the tightening and loosening of the lifting rope adopt a hoist. The selection of the hoist and the length of the lifting rope satisfy the following formula: Hmax + X > Lmax, Hmin + X < Lmin, Lmax - Hmax < X < Lmin - Hmin; where the distance between a certain lifting lug and its corresponding lifting hole is L, the minimum distance is Lmin, and the maximum distance is Lmax; the total length of the hoist (including the hoist body, chain, and hook head length) used at this lifting lug is H, the minimum length of the hoist is Hmin, the maximum length is Hmax, and the total length of the additional rope and shackle under this lifting lug is X.

[0014] After adopting the above technical solution, the beneficial effects of the present invention are:

[0015] The present invention relates to an overturning hoisting structure for a floating crane ship propeller and a method for installing the propeller, which realizes that the propeller enters below the hull in a side-lying state, and then is installed while being overturned in the dock. Through the overturning installation method, the propeller is gradually adjusted from the side-lying storage attitude to the normal installation attitude during the installation process. The propeller can be transported to below the hull in a side-lying state, avoiding the problem of insufficient space below the hull during the normal transportation of the propeller. Thus, the propeller installation operation can be moved to the dock for implementation. When the propeller is installed in the dock, the installation accuracy is improved, the installation cycle of the propeller is effectively shortened, the operation time of the ship in the dock is reduced, and the construction cost of the shipyard is lowered. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a sectional view of the mid-axis of the propeller well in the hull section of the present invention along the ship length direction;

[0017] Figure 2 is a front view of the propeller;

[0018] Figure 3 is Figure 2 a side view of

[0019] Figure 4 is Figure 2 a top view of

[0020] Figure 5 is a schematic diagram of the position of the propeller and the installation of the lifting rope in the first stage;

[0021] Figure 6 is a schematic diagram of the position of the propeller and the installation of the lifting rope in the second stage;

[0022] Figure 7 is a schematic diagram of the position of the propeller and the installation of the lifting rope in the third stage;

[0023] Figure 8 is a schematic diagram of the position of the propeller and the installation of the lifting rope in the fourth stage;

[0024] Figure 9 is a schematic diagram of the position of the propeller and the installation of the lifting rope in the fifth stage;

[0025] Figure 10 is a schematic diagram of the position of the propeller and the installation of the lifting rope in the sixth stage;

[0026] Figure 11 is a schematic diagram of the position of the propeller and the installation of the lifting rope in the seventh stage.

[0027] In the figure, 1 is the hull subassembly, 11 is the first set of lifting lugs, 12 is the second set of lifting lugs, 13 is the third set of lifting lugs, 14 is the fourth set of lifting lugs, 15 is the fifth set of lifting lugs, 16 is the thruster well, 161 is the central axis, 2 is the thruster, 21 is the first set of lifting holes, 22 is the second set of lifting holes, 23 is the third set of lifting holes, 24 is the mounting flange, 25 is the wheel cover, 3 is the lifting rope, and 4 is the flatbed trolley. Detailed implementation manners

[0028] The present invention will be further described below with reference to the accompanying drawings.

[0029] All orientations involved in this specification are based on the orientation when a thruster flipping and hoisting structure of a floating crane ship and a method for installing a thruster of the present invention are working properly, without limiting their orientations during storage and transportation, only representing relative positional relationships and not absolute positional relationships.

[0030] Embodiment 1:

[0031] As Figure 1 , Figure 2 , Figure 3 and Figure 4 collectively show, a thruster flipping and hoisting structure of a floating crane ship includes a set of lifting lugs provided on the hull subassembly 1 and a set of lifting holes provided on the thruster 2.

[0032] There are five sets of lifting lugs, each set includes two lifting lugs, and the two lifting lugs are symmetrically arranged along the longitudinal section of the central axis 161 of the thruster well 16 in the ship length direction. The distance between the two lifting lugs and the axis is about 1.5 m. The specification requirements for the lifting lugs are that any two lifting lugs can bear the weight of the entire thruster 2, and a margin of 1.2 times the coefficient is reserved to ensure the safety during the hoisting process.

[0033] By symmetrically arranging the lifting lugs on both sides of the thruster well 16, stable force can be applied simultaneously on both sides during the hoisting process, ensuring the stable and reliable operation of the thruster 2 when it is hoisted into the thruster well 16. By providing multiple sets of lifting lugs, the multiple sets of lifting lugs cooperate to enable the attitude and position of the thruster 2 to be adjustable during the installation process.

[0034] The five groups of lifting lugs are the first group of lifting lugs 11, the second group of lifting lugs 12, the third group of lifting lugs 13, the fourth group of lifting lugs 14 and the fifth group of lifting lugs 15 respectively. Both the first group of lifting lugs 11 and the second group of lifting lugs 12 are located at the bottom outside the cabin of the hull block 1, and the connecting line of the two lifting lugs of the first group of lifting lugs 11 and the connecting line of the two lifting lugs of the second group of lifting lugs 12 are on different sides of the central axis 161 of the thruster well 16. The third group of lifting lugs 13, the fourth group of lifting lugs 14 and the fifth group of lifting lugs 15 are located at the top of the cabin of the hull block 1, and the connecting line of the two lifting lugs of the third group of lifting lugs 13 intersects the central axis 161 of the thruster well 16, and the fourth group of lifting lugs 14 and the fifth group of lifting lugs 15 are respectively on different sides of the central axis 161 of the thruster well 16.

[0035] There are three groups of lifting holes, and each group includes two lifting holes, which are the first lifting hole group 21, the second lifting hole group 22 and the third lifting hole group 23 respectively. Among them, the two lifting holes of the first lifting hole group 21 and the two lifting holes of the second lifting hole group 22 are arranged on the inner side of the installation flange 24, on the same circle with the center of the central hole of the installation flange 24 as the center, and the two lifting holes of the first lifting hole group 21 and the two lifting holes of the second lifting hole group 22 are symmetrically arranged on both sides of a certain diameter of the installation flange 24; the third lifting hole group 23 is arranged on the rib plate outside the shroud 25 of the impeller of the thruster 2, and the lifting holes of the two third lifting hole groups 23 are symmetrically distributed with respect to the vertical plane of the impeller shaft of the thruster 2; lifting rings are fixed in the lifting holes.

[0036] Lifting ropes 3 are arranged between the lifting lug groups and their corresponding lifting hole groups. In this embodiment, a hoist is used to control the tightening or loosening of the lifting ropes 3. In practical applications, it can also be controlled by manpower or a winch, etc. This embodiment does not limit this. The distance between the two lifting lugs in the lifting lug group is greater than the distance between the two lifting holes in the corresponding lifting hole group, ensuring that the attitude of the thruster 2 can be adjusted during lifting.

[0037] Embodiment 2:

[0038] As Figure 5 - Figure 11 As shown together, a method for installing a thruster using the floating crane thruster flipping and hoisting structure described in Embodiment 1 includes the following steps:

[0039] S1: As Figure 5 shown, use a flatbed trolley 4 to send the thruster 2 in a lying state to a predetermined position below the hull block 1.

[0040] S2: As Figure 5As shown, the suspension ropes 3 at the first group of lifting lugs 11, the second group of lifting lugs 12, the third group of lifting lugs 13, the fourth group of lifting lugs 14 and the fifth group of lifting lugs 15 are connected to the lifting rings within the corresponding lifting hole groups. Among them, the two lifting lugs of the first group of lifting lugs 11 are respectively and correspondingly connected to the two lifting rings within the third lifting hole group 23, the two lifting lugs of the second group of lifting lugs 12 and the two lifting lugs of the fifth group of lifting lugs 15 are respectively and correspondingly connected to the two lifting rings within the first lifting hole group 21, the two lifting lugs of the fourth group of lifting lugs 14 are respectively and correspondingly connected to the two lifting rings within the second lifting hole group 22, and the suspension rope 3 at the third group of lifting lugs 13 is suspended.

[0041] S3: As Figure 6 shown, each suspension rope 3 is tightened. The weight of the thruster 2 is mainly borne by the suspension ropes 3 at the first group of lifting lugs 11 and the second group of lifting lugs 12. The fourth group of lifting lugs 14 and the fifth group of lifting lugs 15 are mainly used to adjust the position and attitude of the thruster, and lift the thruster 2 off the flat trolley 4.

[0042] S4: As Figure 7 and Figure 8 jointly shown, the suspension rope 3 at the fifth group of lifting lugs 15 is tightened, and the suspension rope 3 at the first group of lifting lugs 11 is relaxed, causing the upper end of the thruster 2 to lift. At the same time, the suspension rope 3 at the second group of lifting lugs 12 is tightened, and the thruster 2 moves towards the stern side, thereby adjusting the upper end of the thruster 2 below the thruster well 16 and gradually moving the gearbox part of the thruster 2 into the thruster well 16.

[0043] S5: As Figure 9 shown, the suspension rope 3 at the second group of lifting lugs 12 is removed, the suspension ropes 3 at the fourth group of lifting lugs 14 and the fifth group of lifting lugs 15 are tightened, and the suspension rope 3 at the first group of lifting lugs 11 continues to be relaxed, causing the thruster 2 to gradually adjust to the vertical normal position. The main weight of the thruster 2 is borne by the suspension ropes 3 at the fourth group of lifting lugs 14 and the fifth group of lifting lugs 15.

[0044] S6: As Figure 10 shown, two suspension ropes 3 are set at the third group of lifting lugs 13, respectively connecting the first lifting hole group 21 and the second lifting hole group 22, and the suspension rope 3 at the first group of lifting lugs 11 is removed; to avoid interference during the lifting of the thruster 2.

[0045] S7: As Figure 11 shown, the suspension rope 3 at the third group of lifting lugs 13 is tightened, the thruster 2 is lifted into the thruster well 16, the mounting flange 24 of the thruster 2 is installed on the top flange at the top of the thruster well 16, and the process screw is used for guiding and centering. The mounting flange 24 and the top flange are trial - fitted and the joint surface clearance is checked.

[0046] S8: Loosen the suspension ropes 3 at the third set of lifting lugs 13, the fourth set of lifting lugs 14 and the fifth set of lifting lugs 15, lower the thruster 2, lower the thruster 2 to about 200 mm from the top flange. Immediately apply sealant to the mounting flange 24 of the thruster 2 and then lift the thruster 2 up, ensuring that the mounting flange 24 of the thruster 2 is smoothly joined with the top flange of the hull. Install flat gaskets and bolts, and tighten the bolts in a diagonal order to ensure that the thruster 2 is fully pressed, thus completing the installation of the thruster 2.

[0047] Before the installation operation of the thruster 2, the installation process should be simulated to determine the attitude and position of the thruster 2 at each stage during the installation process and determine the length of the suspension rope 3.

[0048] Determination method of the suspension rope 3 and the hoist:

[0049] The selection of the hoist and the length of the suspension rope 3 should meet the following formula: Hmax + X > Lmax, Hmin + X < Lmin, Lmax - Hmax < X < Lmin - Hmin; where, the distance between a certain lifting lug and its corresponding lifting hole is L, the minimum distance is Lmin, and the maximum distance is Lmax; the total length of the hoist used at this lifting lug (including the length of the hoist body, the chain and the hook head) is H, the minimum length of the hoist is Hmin, the maximum length is Hmax, and the total length of the additional rope and shackle under this lifting lug is X.

[0050] After calculation, select a hoist and the corresponding suspension rope 3 of appropriate specifications to ensure that the thruster 2 can be adjusted to the preset attitude and position during the actual installation process of the thruster 2; according to the above calculation formula, the carrying base surface of the flat trolley carrying the thruster 2 should be as low as possible, so as to increase the minimum distance Lmin between the lifting hole of the thruster 2 and the hull lifting point. On this basis, the position of the thruster 2 should be as close as possible to the center position of the thruster well 16, so as to reduce the maximum distance Lmax between the lifting hole of the thruster 2 and the hull lifting lug. By increasing Lmin and reducing Lmax, the selection range of the hoist specifications can be expanded, and the feasibility of the scheme implementation can be improved.

[0051] Certainly, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the substantial scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A flipping and hoisting structure for a floating crane ship propeller, characterized in that: It includes a lifting lug group arranged on the hull block and a lifting hole group arranged on the thruster; There are five groups of the lifting lug groups, each group includes two lifting lugs, and the two lifting lugs are symmetrically arranged along the longitudinal section of the thruster well axis in the ship length direction; The first group of lifting lug groups and the second group of lifting lug groups are located at the bottom outside the cabin, and the connection line of the two lifting lugs of the first group of lifting lug groups and the connection line of the two lifting lugs of the second group of lifting lug groups are on different sides of the thruster well axis. The third group of lifting lug groups, the fourth group of lifting lug groups and the fifth group of lifting lug groups are located at the top of the cabin, and the connection line of the two lifting lugs of the third group of lifting lug groups intersects the thruster well axis. The connection line of the two lifting lugs of the fourth group of lifting lug groups and the connection line of the two lifting lugs of the fifth group of lifting lug groups are on different sides of the thruster well axis; There are three groups of the lifting hole groups, each group includes two lifting holes. The two lifting holes of the first lifting hole group and the two lifting holes of the second lifting hole group are arranged on the mounting flange and are located on the same circle with the center of the central hole of the mounting flange as the center. The two lifting holes of the first lifting hole group and the two lifting holes of the second lifting hole group are symmetrically arranged on both sides of a certain diameter of the mounting flange; The third lifting hole group is arranged on the rib plate outside the shroud of the thruster impeller, and the two lifting holes of the two third lifting hole groups are symmetrically distributed along the vertical plane of the thruster impeller shaft; A lifting ring is fixed in the lifting hole of the lifting hole group; A lifting rope is arranged between the lifting lug group and its corresponding lifting hole group, and the lifting rope can be tightened or loosened; Any two lifting lugs can bear the weight of the whole thruster.

2. The flipping and hoisting structure of a floating crane ship propeller according to claim 1, wherein: The weight that any two lifting lugs can bear is 1.2 times the weight of the whole thruster.

3. A method for installing a thruster using the flipping and hoisting structure of a floating crane ship thruster according to any one of claims 1-2, characterized in that: It includes the following steps: S1: Use a flatbed trolley to send the thruster in a side-lying state to a predetermined position below the hull; S2: Connect the lifting ropes at the first group of lifting lug groups, the second group of lifting lug groups, the third group of lifting lug groups, the fourth group of lifting lug groups and the fifth group of lifting lug groups with the lifting rings in the corresponding lifting hole groups. Among them, the two lifting lugs of the first group of lifting lug groups are connected to the two lifting rings of the third lifting hole group one by one. The two lifting lugs of the second group of lifting lug groups and the two lifting lugs of the fifth group of lifting lug groups are both connected to the two lifting rings of the first lifting hole group one by one. The two lifting lugs of the fourth group of lifting lug groups are connected to the two lifting rings of the second lifting hole group one by one; S3: Tighten each lifting rope to lift the thruster off the flatbed trolley; S4: Tighten the lifting rope at the fifth group of lifting lug groups and loosen the lifting rope at the first group of lifting lug groups to lift the upper end of the thruster. At the same time, tighten the lifting rope at the second group of lifting lug groups, and the thruster moves towards the stern side, so as to adjust the upper end of the thruster below the thruster well and gradually make the gearbox part of the thruster enter the thruster well; S5: Remove the lifting rope at the second group of lifting lug groups, tighten the lifting ropes at the fourth group of lifting lug groups and the fifth group of lifting lug groups, and continue to loosen the lifting rope at the first group of lifting lug groups to gradually adjust the thruster to a vertical normal position; S6: Set two lifting ropes at the third group of lifting lug groups, connect them to the first lifting hole group and the second lifting hole group respectively, and remove the lifting rope at the first group of lifting lug groups; S7: Tighten the lifting ropes at the third group of lifting lug groups, lift the thruster into the thruster well, and conduct a trial assembly of the thruster and the hull and check the joint surface clearance; S8: Loosen the suspension ropes at the third, fourth, and fifth sets of lifting lugs, lower the thruster, apply sealant to the installation flange surface of the thruster, immediately lift the thruster after application, ensure the smooth engagement of the thruster flange surface with the hull, install flat gaskets and bolts, and tighten the bolts in a diagonal order to ensure that the thruster is fully compressed, completing the installation of the thruster.

4. The method for installing a thruster according to claim 3, wherein: Before the thruster installation operation, simulate the installation process to determine the attitude and position of the thruster at each stage during installation and determine the length of the suspension ropes.

5. The method for installing a thruster according to claim 4, characterized in that: The tightening and loosening of the suspension ropes are carried out using a hoist. The selection of the hoist and the length of the suspension rope satisfy the following formula: Hmax + X > Lmax, Hmin + X < Lmin, Lmax - Hmax < X < Lmin - Hmin; where the distance between a certain lifting lug and its corresponding lifting hole is L, the minimum distance is Lmin, and the maximum distance is Lmax; the total length of the hoist used at this lifting lug is H, the minimum length of the hoist is Hmin, the maximum length is Hmax, and the total length of the additional rope and shackle under this lifting lug is X.

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