Crane

Abstract

The invention relates to a crane which comprises a base, a stand column, a transverse main beam fixedly connected to the top end of the stand column, upper and lower rails arranged on the side face of the main beam, an auxiliary beam assembly driven by an electric push rod to slide on the upper rail, a first steel rope wound by double pulleys at the outer end of the auxiliary beam assembly, and an auxiliary beam assembly connected to the lower rail in a sliding mode. A movable hook assembly is arranged at the lower end of the auxiliary beam assembly, an electric push rod drives an auxiliary beam to enable the first-stage speed multiplication mechanism and the second-stage speed multiplication mechanism which extend the stroke of the auxiliary beam assembly by two times to be linked, and finally four-time stroke amplification of the hook assembly is achieved. The equipment is provided with a rotatable stand column, a guide groove and an adjustable limiting device, movement flexibility and structural stability are enhanced, a safety monitoring system integrates a three-level early warning mechanism, stroke code detection, fault self-diagnosis and an emergency strategy, displacement is monitored in real time, intelligent response is achieved, the over-limit risk is effectively prevented and controlled, and the safety of the equipment is improved. According to the design, through cooperation of mechanical linkage optimization and intelligent monitoring, efficient operation and safe operation are both considered, and the method is suitable for a large-span scene.

Description

Technical Field

[0001] The present invention relates to the technical field of cranes, and in particular to a crane. Background Art

[0002] As an important part of industrial development, cranes are increasingly used in infrastructure construction, industrial production, port trade, aerospace and other fields. With the continuous development of the international economy, the crane industry will usher in more development opportunities and challenges. When hoisting goods at different distances, existing cranes change the length of the boom by adjusting the angle of the boom to meet the needs of hoisting goods at different distances. However, in order to achieve a larger working range, a longer boom is required, which will cause the equipment itself to occupy more space; at the same time, as the length of the boom increases, its stability will be affected, especially when hoisting heavier goods, it is more likely to sway and become unstable. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a crane, which mainly solves the technical problem that in order to achieve a larger working range, a longer boom needs to be set, which causes the equipment to occupy a larger space; at the same time, the longer boom is prone to swinging when hoisting heavier goods.

[0004] To achieve the above object, the present invention is achieved through the following technical solutions:

[0005] A crane comprises: a base, a column fixed on the base, a transverse main beam fixedly connected to the top of the column; an upper track, a lower track and an electric push rod arranged in parallel are provided on the side of the main beam, and the telescopic end of the movable rod of the electric push rod is fixedly connected to an auxiliary beam assembly; the auxiliary beam assembly comprises an auxiliary beam body slidably connected to the upper track through a slider bearing, and a first steel cable is wound around the outer end of the auxiliary beam assembly through two first pulleys with an axial center distance L, the upper section of the first steel cable is anchored to a fixed point near the middle of the main beam, and the lower section is connected to a sub-beam assembly that slides on the lower track through a slider bearing, and a movable hook assembly is provided at the lower end of the sub-beam assembly; the auxiliary beam assembly and the movable rod of the electric push rod constitute a first-stage speed-multiplying mechanism, so that the displacement of the sub-beam assembly is twice the stroke of the movable rod.

[0006] Furthermore, the sub-beam assembly includes a connecting plate and a sub-beam body, the upper end of the connecting plate is slidably connected to the lower track through a slider bearing and is fixedly connected to the lower section of the first steel cable; the sub-beam body is fixedly connected to the lower end of the connecting plate and is arranged parallel to and directly below the main beam.

[0007] Furthermore, the sub-beam assembly also includes a second pulley arranged at both ends of the sub-beam body and a second steel cable wound between the two second pulleys, the upper section of the second steel cable is anchored at a fixed point near the rear end of the main beam, and the lower section is connected to the movable hook assembly; the sub-beam assembly and the first steel cable constitute a two-stage speed-multiplying mechanism, so that the displacement of the movable hook assembly is 4 times the stroke of the movable rod of the electric push rod.

[0008] Furthermore, the mobile hook assembly includes an electric hoist and a mobile trolley with sliding wheels, the mobile trolley is fixedly connected to the lower section of the second steel cable and the sliding wheels of the mobile trolley are slidably connected in the auxiliary beam body; the electric hoist is fixedly connected to the lower end of the mobile trolley.

[0009] Furthermore, a guide groove is provided at the lower end of the auxiliary beam body, and the sliding wheel of the movable trolley is slidably connected in the guide groove.

[0010] Furthermore, the column is rotatably arranged on the base.

[0011] Furthermore, the crane also includes a safety monitoring system, including:

[0012] The stroke detection module uses an encoder to monitor the displacement S of the electric push rod in real time;

[0013] Limit sensors are set at both ends of the main beam at 400 mm from the end points to detect the displacement limit of the sub-beam assembly;

[0014] An audible and visual alarm is electrically connected to the control system;

[0015] When the displacement of the mobile hook assembly is D=4S, and S≤L, the limit sensor triggers a three-level control signal: the first level activates the yellow warning light when D≥3.8L, the second level cuts off the power supply of the electric push rod when D≥3.95L, and the third level starts the sound and light alarm when D=4L and uploads the signal to the central control system.

[0016] Furthermore, the electric push rod is provided with a stroke limiting mechanism, including a mechanical stopper fixed on the electric push rod cylinder and a mechanical micro switch linked to the movable rod. When the displacement of the movable rod reaches S=L, the movable rod contacts the mechanical stopper and triggers the micro switch to cut off the power supply of the electric push rod.

[0017] Furthermore, the mechanical stopper is an adjustable metal limit block, which is fixed to the cylinder end of the electric push rod through horizontal thread adjustment.

[0018] Furthermore, the safety monitoring system also includes a fault self-diagnosis module, which is configured to: monitor the working status of the limit sensor in real time; when any sensor fails, automatically switch to the backup control strategy, and the backup strategy includes: if the dual limit sensors fail at the same time, directly trigger the third-level control signal.

[0019] The above technical solution has the following advantages or beneficial effects:

[0020] In the crane described in the present invention, in order to achieve a larger working range, it is only necessary to start the electric push rod to extend the movable rod of the electric push rod. Among them, when the movable rod of the electric push rod is extended to a certain distance, it will drive the auxiliary beam body to slide a corresponding distance on the upper track, and then drive the first steel cable to move counterclockwise between the two first pulleys on the auxiliary beam body, and finally drive the sub-beam assembly to slide on the lower track and move twice the extension distance of the movable rod in the direction away from the column. Similarly, when the movable rod of the electric push rod is retracted, it will drive the first steel cable to move clockwise between the two first pulleys on the auxiliary beam body, and finally drive the sub-beam assembly and the mobile hook assembly to move twice the retraction distance of the movable rod in the direction close to the column. At the same time, a two-level speed-multiplying mechanism is formed between the sub-beam assembly and the first steel cable, which finally makes the mobile hook assembly move 4 times the stroke of the movable rod in the direction away from the column or close to the column.

[0021] In extreme cases, the crane is extended and retracted by the electric push rod 6. The safety monitoring system monitors the displacement S in real time and calculates the hook displacement D=4S. The distance between the two axles of the two first pulleys is L. When D approaches the preset threshold (yellow light warning at 3.8L, power off at 3.95L, sound and light alarm at 4L), the graded protection is automatically triggered. The maximum stroke of the movable rod S=L can be set by adjusting the horizontal position of the mechanical block at the end of the electric push rod 6. When the limit is exceeded, the block triggers the micro switch 19 to force the machine to stop. If the limit sensor 17 fails, the system can automatically enable the backup strategy. When the dual sensors fail, the highest level alarm is directly activated to ensure safe response in extreme cases.

[0022] In summary, the crane of the present invention uses a first-stage speed-doubling mechanism, in which the electric push rod drives the auxiliary beam assembly to expand the stroke of the sub-beam assembly by 2 times, and cooperates with the second-stage speed-doubling mechanism to finally allow the mobile hook assembly to achieve a 4-fold stroke of the movable rod, thereby significantly improving the operating range and movement efficiency; combined with the rotatable column, guide groove structure and adjustable mechanical limit design, the flexibility and stability of the equipment are enhanced; at the same time, it is equipped with a safety monitoring system with three-level early warning, stroke coding detection, fault self-diagnosis and backup strategy, which monitors the displacement in real time and responds in a graded manner, effectively preventing the risk of over-limit and ensuring safe and reliable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1is an enlarged view of the auxiliary beam assembly in the crane of the present invention;

[0024] Figure 2 is an enlarged view of a secondary beam assembly in the crane of the present invention;

[0025] Figure 3 It is a schematic diagram of the overall structure of the crane of the present invention;

[0026] Figure 4 yes Figure 3 A partial enlarged view of the middle A;

[0027] Figure 5 yes Figure 3 A partial enlarged view of point B in the middle;

[0028] Figure 6 yes Figure 4 A partial enlarged view of point c in the middle;

[0029] Figure 7 yes Figure 4 The local enlarged view at point d in the middle;

[0030] Figure 8 yes Figure 5 The local enlarged view at e in the middle;

[0031] Fig. 9 yes Figure 5 The local enlarged image at point f in the middle;

[0032] Fig.10 It is a structural schematic diagram of the movable rod of the electric push rod in the crane of the present invention when the movable rod is extended to the full stroke;

[0033] Description of labels:

[0034] 1. Base, 2. Column, 3. Main beam, 4. Upper track, 5. Lower track, 6. Electric push rod, 7. Auxiliary beam body, 8. First pulley, 9. First steel cable, 10. Connecting plate, 11. Sub-beam body, 12. Second pulley, 13. Second steel cable, 14. Electric hoist, 15. Mobile trolley, 16. Slider bearing, 17. Limit sensor, 100, First fixed connection point, 200, Second fixed connection point, 300, Third fixed connection point, 400, Fourth fixed connection point. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0036] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 the present invention.

[0037] Please refer to the attached Figure 1 To Attachment Fig.10 The first embodiment of the present invention provides a crane, comprising a base 1, a column 2 arranged on the base 1, a transversely arranged main beam 3 fixedly arranged on the top of the column 2, an upper rail 4, a lower rail 5 and an electric push rod 6 arranged transversely and parallelly on the side of the main beam 3, the movable rod of the electric push rod 6 is arranged away from the column 2, and the end of the movable rod is fixedly connected to the auxiliary beam assembly. The auxiliary beam assembly includes an auxiliary beam body 7 which is slidably arranged on the upper rail 4 through a slider bearing 16 and one end of which is fixedly connected to the end of the movable rod of the electric push rod 6, two first pulleys 8 with an axial center distance of L are arranged on the outer end of the auxiliary beam body 7, and a first steel cable 9 is connected between the two first pulleys 8, and the auxiliary beam body 7, the first pulley 8 and the first steel cable 9 together constitute the auxiliary beam assembly.

[0038] Please refer to the attached Figure 1 To Attachment Fig.10 The upper section of the first steel cable 9 is anchored at a fixed point near the middle of the main beam 3 (such as Figure 8 The first fixed connection point 100 in the figure), the end of the lower section of the first steel cable 9 close to the column 2 is used to be fixedly connected to the sub-beam assembly slidably connected to the lower track 5 through the slider bearing 16 (such as Figure 6 The second fixed connection point 200 in the auxiliary beam assembly is connected to the lower end of the auxiliary beam assembly. It can be understood that in order to achieve a larger working range, the present invention only needs to start the electric push rod 6 to extend the movable rod of the electric push rod 6.

[0039] Among them, when the movable rod of the electric push rod 6 extends a certain distance, it will drive the auxiliary beam body 7 to slide a corresponding distance on the upper track 4, and then drive the first steel cable 9 to move counterclockwise between the two first pulleys 8 on the auxiliary beam body 7, and finally drive the sub-beam assembly and the moving hook assembly to slide on the lower track 5 and move twice the extension distance of the movable rod in the direction away from the column 2; similarly, when the movable rod of the electric push rod 6 retracts, it will drive the first steel cable 9 to move clockwise between the two first pulleys 8 on the auxiliary beam body 7, and finally drive the sub-beam assembly and the moving hook assembly to move twice the retraction distance of the movable rod in the direction close to the column 2. It can be seen that the auxiliary beam assembly and the movable rod of the electric push rod 6 constitute a first-level speed mechanism, so that the displacement of the sub-beam assembly is twice the stroke of the movable rod.

[0040] In summary, it can be seen that the movable rod of the electric push rod 6 in the present invention only needs to extend a small stroke to finally allow the mobile hook assembly to move a large distance, so as to hoist goods at a longer distance, thereby improving the existing situation where a longer boom needs to be set up to achieve a larger working range, which will cause the equipment to occupy a larger space; at the same time, a longer boom is also prone to swinging when hoisting heavier goods.

[0041] Preferably, the stroke of the electric push rod 6 in this embodiment is 1750 mm. However, those skilled in the art should understand that in other embodiments, the stroke of the electric push rod 6 may be larger or smaller, and the present invention does not make specific limitations.

[0042] Please refer to the attached Figure 1 To Attachment Fig.10 In one preferred embodiment, the sub-beam assembly includes a connecting plate 10 and a sub-beam body 11, wherein the upper end of the connecting plate 10 is slidably connected to the lower rail 5 through a slider bearing 16 and is fixedly connected to the lower section of the first steel cable 9 (such as Figure 6 The auxiliary beam body 11 is fixedly connected to the lower end of the connecting plate 10 and is arranged in parallel directly below the main beam 3, so that the lower section of the first steel cable 9 can simultaneously drive the connecting plate 10 and the auxiliary beam body 11 to move when moving.

[0043] Please refer to the attached Figure 2 To Attachment Fig. 9 In one preferred embodiment, the sub-beam assembly further includes a second pulley 12, which is disposed at both ends of the sub-beam body 11, and a second steel cable 13 is connected between the two second pulleys 12. The connecting plate 10, the sub-beam body 11, the second pulley 12 and the second steel cable 13 together constitute the sub-beam assembly. The upper section of the second steel cable 13 is anchored at a fixed point (such as Fig. 9 The third fixed connection point 300 in the figure), the end of the lower section of the second steel cable 13 close to the column 2 is used to be fixedly connected to the mobile hook assembly (such as Figure 7The fourth fixed connection point 400 in the sub-beam assembly is formed by the sub-beam assembly and the first steel cable 9 as a secondary speed mechanism, so that the displacement of the mobile hook assembly is 4 times the stroke of the movable rod of the electric push rod 6. It can be understood that when the connecting plate 10 and the sub-beam body 11 in the sub-beam assembly of the present invention are driven by the primary speed mechanism to move in the direction away from the column 2, the second steel cable 13 will be driven to move counterclockwise between the two second pulleys 12, thereby driving the mobile hook assembly to move twice the moving distance of the sub-beam body 11 in the direction away from the column 2, that is, four times the extension distance of the movable rod of the electric push rod 6. In summary, it can be seen that when the movable rod of the electric push rod 6 in the present invention is extended a certain distance, it will eventually drive the mobile hook assembly to move four times the extension distance of the movable rod in the direction away from the column 2. For example: the stroke of the electric push rod 6 is 1750mm. When the movable rod of the electric push rod 6 is extended to the full stroke, the mobile hook assembly will move a distance of 7000mm.

[0044] Similarly, when the movable rod of the electric push rod 6 retracts, it will drive the first steel cable 9 to move clockwise between the two first pulleys 8 on the auxiliary beam body 7, thereby driving the auxiliary beam assembly and the mobile hook assembly to move twice the retraction distance of the movable rod in the direction close to the column 2. Since the connecting plate 10 is fixedly connected to the lower section of the first steel cable 9, the connecting plate 10 and the auxiliary beam body 11 will move in the direction close to the column 2 with the lower section of the first steel cable; at this time, the second steel cable 13 will move clockwise between the two second pulleys 12, and finally make the retraction displacement of the mobile hook assembly 4 times the stroke of the movable rod of the electric push rod 6. For example: the stroke of the electric push rod 6 is 1750mm. When the movable rod of the electric push rod 6 retracts the full stroke, the mobile hook assembly will retract and move a distance of 7000mm.

[0045] Please refer to the attached Figure 4 , Attachment Figure 7 In one preferred embodiment, the mobile hook assembly includes an electric hoist 14 and a mobile trolley 15 with sliding wheels, and the mobile trolley 15 is fixedly connected to the lower section of the second steel cable 13 (such as Figure 7 The fourth fixed connection point 400 in the auxiliary beam body 11 is connected to the movable trolley 15, and the sliding wheel of the movable trolley 15 is slidably connected in the guide groove at the lower end of the auxiliary beam body 11 to facilitate the movement of the movable trolley 15. The electric hoist 14 is fixedly connected to the lower end of the movable trolley 15 to move synchronously with the movable trolley 15.

[0046] Please refer to the attached Figure 3 In a preferred embodiment, the column 2 is rotatably disposed on the base 1 to facilitate lifting of goods in different orientations.

[0047] Preferably, the crane also includes a safety monitoring system, which includes a stroke detection module, a limit sensor 17, an audible and visual alarm and a control system; the stroke detection module monitors the displacement S of the electric push rod 6 in real time through an encoder; the limit sensor 17 is installed at both ends of the main beam 3, 400 mm away from the end point of the main beam 3, and is used to detect the displacement limit of the sub-beam assembly; the audible and visual alarm is electrically connected to the control system; when the displacement D of the mobile hook assembly is equal to 4 times the displacement S of the electric push rod 6, and S is less than or equal to L, the limit sensor 17 triggers a three-level control signal, including: the first level activates the yellow warning light when D is greater than or equal to 3.8L, the second level cuts off the power supply of the electric push rod 6 when D is greater than or equal to 3.95L, and the third level starts the audible and visual alarm when D is equal to 4L and uploads an alarm signal to the central control system. It can be seen that the above safety monitoring system can achieve accurate cross-border risk prevention and control through a multi-level early warning mechanism and a safe displacement threshold setting.

[0048] Preferably, the electric push rod 6 is provided with a stroke limiting mechanism, which ensures that the stroke of the electric push rod 6 is controllable and easy to adjust through a mechanical and electrical dual limit design. The stroke limiting mechanism includes a mechanical stopper (not shown in the figure) fixed to the cylinder body of the electric push rod 6, and a mechanical micro switch (not shown in the figure) linked to the movable rod of the electric push rod 6; when the displacement of the movable rod of the electric push rod 6 reaches S equal to L, the movable rod contacts the mechanical stopper (not shown in the figure) and triggers the micro switch (not shown in the figure), thereby cutting off the power supply of the electric push rod 6.

[0049] Preferably, the mechanical stopper (not shown) is an adjustable metal limiter, which is fixed to the cylinder end of the electric push rod 6 by means of horizontal thread adjustment, and is used to accurately limit the maximum stroke of the movable rod.

[0050] Preferably, the safety monitoring system also includes a fault self-diagnosis module, which is configured to monitor the working status of the limit sensor 17 in real time; when any limit sensor 17 fails, the module automatically switches to a backup control strategy, which includes: if two limit sensors 17 fail at the same time, directly triggering the third-level control signal to start the sound and light alarm and upload the alarm signal. It can be seen that the safety monitoring system has a redundant fault-tolerant mechanism to ensure that the system can still trigger the highest level of safety response in extreme cases.

[0051] The following is the method of using the crane of the present invention:

[0052] When the electric hoist 14 needs to move 4m to lift the goods there, it is only necessary to start the electric push rod 6 and extend the movable rod of the electric push rod 6 by 1m, which can eventually drive the mobile hook assembly to move 4m. At this time, the electric hoist 14 can be moved down to a suitable position to hook the goods, so that the goods can be lifted.

[0053] When operating under extreme conditions, the crane is extended and retracted through the electric push rod 6. The safety monitoring system monitors the displacement S in real time and calculates the hook displacement D=4S. The distance between the two axles of the two first pulleys is set to L. When D approaches the preset threshold (yellow light warning at 3.8L, power off at 3.95L, sound and light alarm at 4L), the graded protection is automatically triggered. By adjusting the horizontal position of the mechanical stopper (not shown in the figure) at the end of the electric push rod 6, the maximum stroke of the movable rod S=L can be set. When the limit is exceeded, the stopper triggers the micro switch (not shown in the figure) to force the machine to stop. If the limit sensor 17 fails, the system automatically activates the backup strategy. When the dual sensors fail, the highest level alarm is directly activated to ensure safe response in extreme conditions.

[0054] As described above, the embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some of the technical features therein by equivalents. These modifications or replacements do not deviate the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection scope of the present invention.

Claims

1. A crane, characterized in that: include: A base (1), a column (2) fixedly mounted on the base (1), the top of the column (2) being fixedly connected to a transverse main beam (3); the side of the main beam (3) is provided with an upper track (4), a lower track (5) and an electric push rod (6) arranged in parallel, the telescopic end of the movable rod of the electric push rod (6) being fixedly connected to an auxiliary beam assembly; the auxiliary beam assembly comprises an auxiliary beam body (7) slidably connected to the upper track (4) through a slider bearing (16), the outer end of the auxiliary beam body having a first steel cable (9) wound around two first pulleys (8) with an axial center distance L, the upper section of the first steel cable (9) being anchored to a fixed point near the middle of the main beam (3), the lower section being connected to a sub-beam assembly slidably mounted on the lower track (5) through a slider bearing (16), the lower end of the sub-beam assembly being provided with a movable hook assembly; the auxiliary beam assembly and the movable rod of the electric push rod (6) constitute a first-stage speed-multiplying mechanism, so that the displacement of the sub-beam assembly is twice the stroke of the movable rod.

2. The crane according to claim 1, characterized in that: The auxiliary beam assembly comprises a connecting plate (10) and an auxiliary beam body (11); the upper end of the connecting plate (10) is slidably connected to the lower track (5) via a slider bearing (16) and is fixedly connected to the lower section of the first steel cable (9); the auxiliary beam body (11) is fixedly connected to the lower end of the connecting plate (10) and is arranged parallel to and directly below the main beam (3).

3. The crane according to claim 2, characterized in that: The sub-beam assembly also includes second pulleys (12) arranged at both ends of the sub-beam body (11) and a second steel cable (13) wound between the two second pulleys (12); the upper section of the second steel cable (13) is anchored to a fixed point near the rear end of the main beam (3), and the lower section is connected to the movable hook assembly; the sub-beam assembly and the first steel cable (9) form a two-stage speed-multiplying mechanism, so that the displacement of the movable hook assembly is 4 times the stroke of the movable rod of the electric push rod (6).

4. The crane according to claim 3, characterized in that: The movable hook assembly comprises an electric hoist (14) and a movable trolley (15) having sliding wheels, wherein the movable trolley (15) is fixedly connected to the lower section of the second steel cable (13) and the sliding wheels of the movable trolley (15) are slidingly connected in the auxiliary beam body (11); the electric hoist (14) is fixedly connected to the lower end of the movable trolley (15).

5. The crane according to claim 4, characterized in that: A guide groove is provided at the lower end of the auxiliary beam body (11), and the sliding wheel of the movable trolley (15) is slidably connected in the guide groove.

6. The crane according to claim 1, characterized in that: The column (2) is rotatably arranged on the base (1).

7. The crane according to claim 3, characterized in that: The crane also includes a safety monitoring system, including: A stroke detection module, which uses an encoder to monitor the displacement S of the electric push rod (6) in real time; Limit sensors (17), arranged at both ends of the main beam (3) at a distance of 400 mm from the end points, for detecting the displacement limit of the auxiliary beam assembly; An audible and visual alarm is electrically connected to the control system; When the displacement of the mobile hook assembly is D=4S, and S≤L, the limit sensor triggers a three-level control signal: the first level activates the yellow warning light when D≥3.8L, the second level cuts off the power supply to the electric push rod (6) when D≥3.95L, and the third level starts the sound and light alarm when D=4L and uploads the signal to the central control system.

8. The crane according to claim 1, characterized in that: The electric push rod (6) is provided with a stroke limiting mechanism, comprising a mechanical stopper fixed on the cylinder body of the electric push rod (6) and a mechanical micro switch linked to the movable rod; when the displacement of the movable rod reaches S=L, the movable rod contacts the mechanical stopper and triggers the micro switch to cut off the power supply to the electric push rod (6).

9. The crane according to claim 8, characterized in that: The mechanical stopper is an adjustable metal stopper, which is fixed to the cylinder end of the electric push rod (6) through horizontal thread adjustment.

10. The crane according to claim 1, characterized in that: The safety monitoring system further comprises a fault self-diagnosis module, which is configured to: monitor the working status of the limit sensors (17) in real time; and automatically switch to a backup control strategy when any sensor fails. The backup strategy includes: directly triggering a third-level control signal if the two limit sensors (17) fail at the same time.

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