Hoisting device with anti-bump function

Abstract

The present application relates to the technical field of hoisting machinery safety protection, and particularly relates to a hoisting device with anti-collision function, comprising a crane, a pulley sling assembly connected with a steel rope drum on the crane through a steel rope, a non-contact control switch or a contact type control switch further arranged on the crane, and a steel rope shearing mechanism arranged on the pulley sling assembly to prevent the pulley sling assembly and a hoisted object from being limitedly collided with the top. In the present application, the steel rope shearing mechanism is integrated on the pulley sling assembly. When the collision occurs, the guide column first contacts the bottom of the crane, and the wedge block pushes the shearing knife to actively cut off the steel rope, so that the uncontrolled overload fracture is converted into the controlled active cutting, thereby effectively protecting the hoist, the speed reducer and the steel rope drum assembly from the brute force damage. Meanwhile, the cooperation structure of the anti-falling clamping plate and the anti-falling side wing reliably receives the pulley sling assembly after the steel rope is cut off, thereby preventing the pulley sling assembly from directly falling, and forming the double protection of the active cutting and the passive receiving.

Description

Technical Field

[0001] This invention relates to the field of safety protection technology for lifting machinery, and in particular to a lifting device with anti-overhead collision function. Background Technology

[0002] Cranes are multi-action lifting machines that vertically lift and horizontally move goods within a certain range. They are widely used in industrial production, construction, port loading and unloading, and other fields.

[0003] Preventing the pulley spreader assembly from overshooting the crane during lifting operations is one of the core safety issues in crane machinery protection. When the lifting height limiter malfunctions or the operator mistakenly presses the up button repeatedly, the pulley spreader assembly will continue to move upwards until it collides with the bottom of the crane trolley, i.e., "overshooting". After overshooting, the lifting wire rope often breaks due to the tension exceeding its limit strength, causing the pulley spreader assembly and the hoisted load to fall from a height, resulting in a serious safety accident.

[0004] To address the aforementioned issues, various anti-collision protection solutions have been proposed in the existing technology.

[0005] Regarding limit protection, Chinese utility model patent CN201809071U (publication date June 21, 2010) discloses a crane anti-overrun device, including a main power input circuit for the crane and a branch power supply, namely a hook lifting control circuit. The lifting control circuit is energized and connected to a first limit device, and the main power input circuit is energized and connected to a second limit device, which is located above the first limit device. When the lifting control circuit malfunctions and the first limit device also malfunctions, the hook continues to move upward and contacts the second limit device, at which point the second limit device disconnects to cut off the main power supply to the crane.

[0006] The aforementioned existing technologies all employ electrical limit switches to achieve anti-overhead collision protection. However, the contacts of the limit switches may become stuck due to arc erosion or mechanical jamming, causing the protection function to fail. Related accident cases show that short-circuiting or shielding the lifting height limit switch, failure of the limit switch's mechanical transmission part, or the moving and stationary contacts of the limit device sticking together can all lead to the hook overhead collision, resulting in serious consequences such as wire rope breakage and hook fall. Therefore, relying solely on electrical limit switches is insufficient to fundamentally solve the safety problems caused by overhead collision.

[0007] Existing technologies have the following shortcomings: First, the reliability of electrical limit protection methods is limited; limit switches may fail due to electrical faults or mechanical jamming, and cannot fundamentally prevent overshooting. Second, existing rope breakage protection devices are all passive, only able to support the lifting device after the wire rope breaks, and cannot actively cut the wire rope during overshooting to protect the winch and rope drum assembly from brute force damage. Therefore, a lifting device is needed that can actively cut the wire rope when overshooting occurs and simultaneously reliably support the pulley lifting device assembly to prevent it from falling, in order to overcome the above-mentioned defects of existing technologies. Summary of the Invention

[0008] The purpose of this invention is to provide a lifting device with anti-overload function. By setting a steel rope cutting mechanism on the pulley lifting device assembly, the steel wire rope is actively cut when overloaded, avoiding damage to the winch and steel rope drum assembly due to continuous overload. At the same time, the anti-fall plate at the bottom of the crane cooperates with the anti-fall side wing on the pulley lifting device assembly to receive the cut steel rope and prevent it from falling directly.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This invention provides a lifting device with anti-overhead-rush function, including a crane and a pulley lifting device assembly connected to a steel rope drum on the crane via a steel rope; The crane is also equipped with a non-contact control switch or a contact control switch. The pulley lifting assembly is equipped with a steel rope shearing mechanism to prevent the pulley lifting assembly and the hoisted object from overshooting the limit. A fall arrestor plate is provided at the bottom of the crane to prevent the pulley lifting assembly and the hoisted object from falling; a fall arrestor wing adapted to the fall arrestor plate is provided on the upper side wall of the pulley lifting assembly.

[0010] Furthermore, the non-contact control switch is one of a proximity switch, a photoelectric switch, or a magnetic switch, which triggers the shutdown of the crane's motor by detecting a threshold height of the pulley lifting assembly.

[0011] Furthermore, the contact control switch is a limit switch or a micro switch, which triggers the shutdown of the crane's motor by means of mechanical transmission when the pulley lifting assembly rises.

[0012] Furthermore, a limiting seat is provided on the slide of the crane; the anti-fall plate is set on the limiting seat through a hinge shaft, and a compression spring is provided on the slide of the crane to adjust the lower end claws of the symmetrically arranged anti-fall plates to engage and approach each other, and effectively support and receive the anti-fall wings.

[0013] Furthermore, the pulley lifting device assembly includes a pulley frame, a hook disposed at the bottom of the pulley frame, a side plate disposed on the pulley frame, and pulleys symmetrically disposed on the side plate via a pivot axis; the fall-prevention wings are symmetrically disposed on both sides of the pulley frame; in use, the steel rope is looped onto the pulley.

[0014] Furthermore, a punching support is provided between the side plates, and a shearing blade limiting groove is horizontally opened on the punching support; a shearing blade is limited and installed in the shearing blade limiting groove; an adjusting inclined surface is provided on the end of the shearing blade away from the steel rope; wherein, a guide post is also vertically limited and installed in the punching support, and a wedge block is provided at the lower end of the guide post; the height of the guide post is greater than the upper end face of the side plate; in use, the guide post first contacts the bottom of the crane, thereby descending through the wedge block to push the blade of the shearing blade to extend towards the steel rope, thereby achieving the cutting or severing of the steel rope.

[0015] Furthermore, a spring groove is provided on the shear blade limiting groove, and a limiting spring is provided in the spring groove to limit the movement; wherein, a limiting block is provided at the bottom of the shear blade to contact the limiting spring, thereby preventing the shear blade from sliding out of the shear blade limiting groove and coming into contact with and rubbing against the steel rope during the non-impact phase.

[0016] Furthermore, a reserved hole is provided at the top of the punching support, which connects to the shearing blade limiting groove inside. The guide post is adapted to be inserted into the reserved hole, and the inner diameter of the reserved hole is smaller than the length and width of the top surface of the wedge block.

[0017] Compared with the prior art, the beneficial technical effects of this invention are as follows: By integrating a steel rope cutting mechanism into the pulley lifting device assembly, when an overload occurs, the guide column preferentially contacts the bottom of the crane, and the wedge block pushes the shearing blade to actively cut the steel rope. This transforms uncontrollable overload breakage into controlled active cutting, effectively protecting the winch, reducer, and steel rope drum assembly from brute force damage. Simultaneously, the cooperative structure of the anti-fall plate and anti-fall wing reliably supports the pulley lifting device assembly after the steel rope is cut, preventing it from falling directly, forming a dual protection of active cutting and passive support. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings. Figure 1 This is a schematic diagram of the lifting device with anti-collision function of the present invention; Figure 2 This is a schematic diagram of the pulley lifting device assembly of the lifting device with anti-collision function of the present invention; Figure 3 for Figure 2 Schematic diagram of pulley lifting device assembly; Figure 4 for Figure 3 Enlarged view of a portion of point A in the middle; Figure 5 This is a schematic diagram of the steel rope cutting mechanism on the pulley lifting device assembly; Figure 6 A schematic diagram of the punching support for the steel rope shearing mechanism on the pulley lifting device assembly; Figure 7 This is a schematic diagram of the installation structure for the anti-fall plate.

[0019] Explanation of reference numerals in the attached drawings: 1. Crane; 11. Anti-fall plate; 12. Limit seat; 13. Hinge shaft; 14. Compression spring; 2. Pulley lifting assembly; 21. Hook; 22. Pulley frame; 23. Pulley; 24. Side plate; 25. Guide column; 251. Wedge block; 26. Shearing blade; 261. Limiting spring; 262. Limiting block; 263. Adjusting ramp; 27. Anti-fall side wing; 28. Punching support; 281. Shearing blade limiting groove; 282. Spring groove; 3. Steel rope. Detailed Implementation

[0020] refer to Figure 1 This embodiment discloses a lifting device with anti-overhead-impact function, including a crane 1 and a pulley lifting device assembly 2 connected to the steel rope drum on the crane 1 via a steel rope 3. One end of the steel rope 3 is wound around the steel rope drum of the crane 1, and the other end passes downwards around the pulley 23 of the pulley lifting device assembly 2 and is fixed at an appropriate position on the crane trolley to form a lifting rope system.

[0021] A control switch is fixedly installed at the bottom of the trolley of the crane 1. The function of the control switch is to trigger the shutdown of the hoisting motor of the crane 1 when the pulley spreader assembly 2 rises to a preset height threshold, as the first level of protection against top collision.

[0022] A steel rope cutting mechanism is provided on the pulley lifting assembly 2 to actively cut the steel rope 3 upon impact. A fall arrestor plate 11 is provided at the bottom of the slide of the crane 1, and fall arrestor wings 27 adapted to the fall arrestor plate 11 are provided on the upper side wall of the pulley lifting assembly 2. After the steel rope 3 is cut, the pulley lifting assembly 2 falls under gravity. The fall arrestor wings 27 are caught by the lower claws of the symmetrically arranged fall arrestor plates 11, suspending the pulley lifting assembly 2 below the slide of the crane 1 and preventing it from falling directly.

[0023] In this embodiment, a non-contact control switch is used. The non-contact control switch is one of a proximity switch, a photoelectric switch, or a magnetic switch.

[0024] In practice, the non-contact control switch is fixedly mounted on the crossbeam at the bottom of the crane trolley using an L-shaped mounting bracket. The vertical plate of the mounting bracket is bolted to the web of the crossbeam, and the horizontal plate extends downwards. The proximity switch is fixed to the lower surface of the horizontal plate by a threaded connection or clamp, with its sensing surface facing vertically downwards, pointing towards the rising path of the pulley spreader assembly 2. When the pulley spreader assembly 2 rises to a preset detection distance below the sensing surface (e.g., 20mm to 200mm), the proximity switch outputs a trigger signal. This signal is transmitted to the crane's control cabinet via a wire, and the relay in the control cabinet disconnects the power supply circuit of the hoisting motor.

[0025] When a photoelectric switch is used, the transmitter and receiver of the photoelectric switch are integrated into the same housing, which is fixed to a horizontal plate of the mounting bracket, with the sensing surface facing vertically downwards. The photoelectric switch emits a modulated light signal downwards. The top of the pulley frame 22 of the pulley hanger assembly 2 acts as a reflector. When the pulley frame 22 rises into the effective detection range of the photoelectric switch, the reflected light is received by the receiver, and the photoelectric switch outputs a trigger signal. The effective detection distance of the photoelectric switch can be set from 50mm to 500mm according to actual needs.

[0026] When a magnetic switch is used, a permanent magnet is fixed to the top of the pulley frame 22 of the pulley lifting device assembly 2 by adhesive or screws. The magnetic switch is fixed to the bottom of the crane trolley by a mounting bracket, with its sensing surface facing the magnet. When the pulley lifting device assembly 2 rises into the sensing range of the magnetic switch, the magnetic switch is activated under the action of the magnetic field and outputs a trigger signal.

[0027] In this embodiment, the control switch can also be a contact-type control switch. The contact-type control switch is a limit switch or a micro switch. The housing of the limit switch is bolted to a mounting plate on the bottom of the crane trolley 1. The mounting plate is welded to the lower flange of the crossbeam at the bottom of the trolley. The limit switch's lever extends downwards, and a roller is mounted at the end of the lever. A trigger block is welded to the top of the pulley frame 22 of the pulley lifting assembly 2. When the pulley lifting assembly 2 rises to the installation position of the limit switch, the trigger block pushes the roller at the end of the lever upwards, causing the lever to rotate around its hinge axis, triggering the normally closed contact of the limit switch to open, cutting off the power supply circuit of the hoisting motor.

[0028] When a microswitch is used, it is fixed to the lower surface of the mounting plate with screws, its contacts facing downwards. A top rod extending upwards is bolted to the top of the pulley frame 22 of the pulley lifting assembly 2. When the pulley lifting assembly 2 rises, the upper end of the top rod contacts and presses the contacts of the microswitch, causing the microswitch to actuate and disconnect the power supply circuit of the lifting motor.

[0029] refer to Figure 1 and Figure 7A limiting seat 12 is welded to the bottom of the slide of the crane 1. The limiting seat 12 is a U-shaped channel steel structure with coaxial hinge shaft holes on its two side walls. The fall arrestor plate 11 is an L-shaped or hook-shaped plate with a through hole at its upper end. The hinge shaft 13 passes through the hinge shaft hole of the limiting seat 12 and the through hole at the upper end of the fall arrestor plate 11, rotatably mounting the fall arrestor plate 11 onto the limiting seat 12. The fall arrestor plates 11 are symmetrically arranged on both sides of the rising path of the pulley lifting device assembly 2.

[0030] A compression spring 14 is fitted onto the hinge shaft 13. The compression spring 14 is a torsion spring, with one end abutting against the inner wall of the limiting seat 12 and the other end abutting against the side of the fall arrestor plate 11. The elastic force applied by the compression spring 14 causes the lower claws of the two symmetrically arranged fall arrestor plates 11 to tend to move closer to each other, that is, the opening width between the two claws is slightly smaller than the width of the fall arrestor side wing 27 of the pulley hoist assembly 2.

[0031] refer to Figure 1 The fall arrestor wing 27 is a triangular or trapezoidal plate welded to the outer walls of both sides of the pulley frame 22, with its outer edge extending beyond the outer surface of the side plate 24 of the pulley frame 22. When the pulley hoist assembly 2 is thrust upwards, the upper edge of the fall arrestor wing 27 first contacts the inner surface of the lower end hook of the fall arrestor plate 11, pushing the two fall arrestor plates 11 outwards (overcoming the elastic force of the compression spring 14), allowing the fall arrestor wing 27 to pass through the opening between the two hooks. After the fall arrestor wing 27 has passed through, the compression spring 14 pushes the two fall arrestor plates 11 back to their original position, closing the opening between the two hooks, with the lower surface of the hooks located below the fall arrestor wing 27. If the steel rope 3 is cut at this time, the pulley hoist assembly 2 falls, and the lower surface of the fall arrestor wing 27 is supported by the upper surface of the lower end hook of the fall arrestor plate 11, causing the pulley hoist assembly 2 to be suspended on the fall arrestor plate 11. The materials of the fall arrestor plate 11 and the fall arrestor wing 27 are both low-alloy high-strength structural steel to ensure sufficient load-bearing capacity.

[0032] refer to Figures 2 to 4 The pulley lifting assembly 2 includes a pulley frame 22, a hook 21 fixed to the bottom of the pulley frame 22 by bolts, side plates 24 welded to both sides of the pulley frame 22, and pulleys 23 symmetrically installed on the side plates 24 by means of a rotating shaft and bearings.

[0033] The pulley frame 22 is welded from two vertical web plates and a horizontal partition connecting the web plates, forming a box-shaped structure. The hook 21 is fixed to the hook beam at the bottom of the pulley frame 22 by hook nuts. The side plates 24 are welded to the left and right sides of the pulley frame 22, parallel to the web plates of the pulley frame 22. The pulley 23 is mounted between the two side plates 24 via a rotating shaft, with both ends of the shaft passing through mounting holes on the side plates 24 and supported by bearings. The rope groove of the pulley 23 is adapted to the diameter of the steel rope 3.

[0034] The fall arrestor wings 27 are symmetrically welded to the outer walls of both sides of the pulley frame 22, specifically, to the outer surface of the web of the pulley frame 22, and located above the side plate 24. The upper edge of the fall arrestor wings 27 is lower than the upper surface of the side plate 24 to avoid interfering with the normal operation of the steel rope shearing mechanism.

[0035] refer to Figures 4 to 6 The steel rope shearing mechanism includes a punching support 28, a shearing blade 26, a guide post 25, a wedge block 251, and a limiting spring 261.

[0036] The punching support 28 is a rectangular block welded between two side plates 24. The upper surface of the punching support 28 is lower than the upper end face of the side plate 24. A shearing blade limiting groove 281 is horizontally formed on the punching support 28, penetrating its left and right sides. The shearing blade limiting groove 281 is a rectangular through groove, and its height is slightly greater than the thickness of the shearing blade 26 to ensure that the shearing blade 26 can slide horizontally within it without moving up and down.

[0037] The shearing blade 26 is a rectangular plate-shaped blade with its cutting edge facing the side where the steel rope 3 is located. The shearing blade 26 is slidably mounted within the shearing blade limiting groove 281. An adjusting bevel 263 is machined on the end of the shearing blade 26 away from the steel rope 3 (i.e., the rear end). The angle between the adjusting bevel 263 and the horizontal plane is 30° to 60°, preferably 45°. The cutting edge of the shearing blade 26 is made of cemented carbide or tool steel, and its cutting edge is ground to enhance its cutting ability.

[0038] A spring groove 282 is formed below the shear blade limiting groove 281. The spring groove 282 is a vertical blind hole that communicates with the shear blade limiting groove 281. A limiting spring 261 is provided in the spring groove 282. One end of the limiting spring 261 abuts against the bottom surface of the spring groove 282, and the other end abuts against the limiting block 262 at the bottom of the shear blade 26. The limiting block 262 is welded or integrally formed on the bottom of the shear blade 26 near the rear end.

[0039] A guide hole is vertically formed within the punching support 28. The upper end of the guide hole communicates with the top of the punching support 28, and the lower end communicates with the shearing blade limiting groove 281. The guide post 25 is a cylindrical rod that is slidably installed within the guide hole. A wedge block 251 is welded to the lower end of the guide post 25. The inclined surface of the wedge block 251 slidably engages with the adjusting inclined surface 263 of the shearing blade 26. The angle of the inclined surface of the wedge block 251 is consistent with the angle of the adjusting inclined surface 263.

[0040] The upper end of the guide post 25 extends beyond the upper surface of the side plate 24. In the non-overhead state, the distance h from the upper end of the guide post 25 beyond the upper surface of the side plate 24 is 20mm to 100mm. This distance h determines the timing of the steel rope shearing mechanism's action: when the pulley lifting assembly 2 rises to the point where the upper end of the guide post 25 contacts the bottom of the crane 1, the guide post 25 begins to be pushed downwards.

[0041] A pre-drilled hole with a connecting guide hole is provided at the top of the punching support 28. The inner diameter of the pre-drilled hole is smaller than the length and width of the top surface of the wedge block 251, thereby preventing the wedge block 251 from coming out of the pre-drilled hole. The diameter of the guide post 25 is smaller than the inner diameter of the pre-drilled hole, allowing the guide post 25 to slide freely within the pre-drilled hole.

[0042] The working process of the steel rope shearing mechanism in this embodiment is as follows: When the pulley lifting assembly 2 rises to its limit position, the upper end of the guide post 25 first contacts the bottom structure (or a special stop) of the crane 1 trolley. As the pulley lifting assembly 2 continues to rise, the bottom structure of the crane 1 pushes the guide post 25 downward. The guide post 25 then drives the wedge block 251 at its lower end to move downward along the guide hole.

[0043] When the wedge block 251 moves downward, its inclined surface slides into contact with the adjusting inclined surface 263 at the rear end of the shearing blade 26. Since the inclined surface of the wedge block 251 is inclined from top to bottom away from the steel rope 3, when the wedge block 251 moves downward, its inclined surface pushes the adjusting inclined surface 263 of the shearing blade 26, causing the shearing blade 26 to overcome the elastic force of the limiting spring 261 and slide horizontally towards the steel rope 3.

[0044] The blade of the shearing blade 26 gradually extends out of the opening of the shearing blade limiting groove 281 near the steel rope 3 and comes into contact with the steel rope 3. As the pulley lifting assembly 2 continues to rise, the guide post 25 is pushed further downward, and the wedge block 251 continues to push the shearing blade 26 forward, with the blade applying an increasing shearing force to the steel rope 3.

[0045] During the compression of the limiting spring 261, the limiting block 262 moves downward, increasing the compression of the limiting spring 261. The function of the limiting spring 261 is to keep the shear blade 26 in its initial position within the shear blade limiting groove 281 during the non-impact phase (i.e., when the guide column 25 is not in contact with the bottom of the crane 1), preventing the shear blade 26 from slipping out of the groove due to vibration or gravity and coming into contact with the steel rope 3, thus preventing accidental wear of the steel rope 3 during normal lifting operations.

[0046] When the shearing force applied by the blade of the shearing blade 26 to the steel rope 3 reaches the shear strength limit of the steel rope 3, the steel rope 3 is cut. After the steel rope 3 is cut, the weight of the pulley lifting device assembly 2 and the load is no longer borne by the steel rope 3, and the pulley lifting device assembly 2 begins to fall under the action of gravity.

[0047] After the steel rope 3 is cut, the pulley lifting device assembly 2 falls. During the fall, when the lower surface of the anti-fall wing 27 of the pulley lifting device assembly 2 descends to the height of the upper surface of the lower end hook of the anti-fall plate 11, the lower surface of the anti-fall wing 27 is supported by the lower end hook of the anti-fall plate 11.

[0048] Since the fall arrestor plates 11 are rotatably mounted on the limiting seat 12 via the hinge shaft 13, and the clamping spring 14 causes the lower end hooks of the two fall arrestor plates 11 to tend to approach each other, the opening width between the two hooks is smaller than the width of the fall arrestor side wings 27. During the upward movement of the pulley lifting assembly 2, the fall arrestor side wings 27 push the two fall arrestor plates 11 apart and through the opening; when the pulley lifting assembly 2 falls, the lower surface of the fall arrestor side wings 27 presses against the upper surface of the two hooks. The hooks are subjected to downward pressure under the gravity of the fall arrestor side wings 27, but due to the restriction of the rotation direction of the fall arrestor plates 11 (the hooks can only rotate outward), the hooks will not flip outward due to gravity, but will stably support the fall arrestor side wings 27.

[0049] Thus, the pulley lifting assembly 2 and the object being lifted are suspended below the slide of the crane 1, preventing them from falling directly to the ground.

[0050] Under normal operating conditions, the control switch serves as the first level of protection. When the pulley lifting assembly 2 rises to a preset height threshold, the control switch is triggered, shutting off the power supply circuit to the lifting motor, and the pulley lifting assembly 2 stops rising.

[0051] When the control switch fails (e.g., the sensing element of the proximity switch is damaged, the contacts of the limit switch are stuck, or the lens of the photoelectric switch is blocked by dust), the pulley lifting assembly 2 continues to rise, and the upper end of the guide column 25 contacts the bottom of the crane 1, triggering the action of the steel rope cutting mechanism, and the steel rope 3 is cut.

[0052] The moment the steel rope 3 is cut, the load on the winch and the steel rope drum assembly suddenly disappears. Since the shearing mechanism only activates when the pulley lifting assembly 2 reaches its limit position, the winch has already endured a significant overload torque. The active cutting of the steel rope 3 prevents the winch from continuing to operate under overload conditions, thus protecting the motor, reducer, and steel rope drum assembly from brute force damage. The cut steel rope 3 is wrapped around the steel rope drum, eliminating the risk of injury from wire rope rebound, as the cutting point is located at the punching support 28 of the pulley lifting assembly 2, and both ends of the cut steel rope 3 are constrained by the steel rope drum side and the pulley lifting assembly side, respectively. After the steel rope 3 is cut, the mating structure of the fall arrestor plate 11 and the fall arrestor side wing 27 supports the pulley lifting assembly 2, forming a second level of protection.

[0053] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A lifting device with anti-overhead-rush function, characterized in that, Includes a crane and a pulley lifting device assembly connected to a steel rope drum on the crane via a steel rope; The crane is also equipped with a non-contact control switch or a contact control switch. The pulley lifting assembly is equipped with a steel rope shearing mechanism to prevent the pulley lifting assembly and the hoisted object from overshooting the limit. A fall arrestor plate is provided at the bottom of the crane to prevent the pulley lifting assembly and the hoisted object from falling; a fall arrestor wing adapted to the fall arrestor plate is provided on the upper side wall of the pulley lifting assembly.

2. The lifting device with anti-overhead function according to claim 1, characterized in that: The non-contact control switch is one of a proximity switch, photoelectric switch, or magnetic switch, which triggers the shutdown of the crane motor by detecting a threshold height of the pulley lifting assembly.

3. The lifting device with anti-overhead function according to claim 1, characterized in that: The contact control switch is a limit switch or a micro switch, which is used to trigger the motor of the crane to shut down by means of mechanical transmission when the pulley lifting assembly is raised.

4. The lifting device with anti-overhead function according to claim 1, characterized in that: A limit seat is provided on the slide of the crane; the anti-fall plate is set on the limit seat through a hinge shaft, and a compression spring is provided on the slide of the crane to adjust the lower end claws of the symmetrically arranged anti-fall plates to engage and approach each other, and effectively support and receive the anti-fall wings.

5. The lifting device with anti-overhead function according to claim 1, characterized in that: The pulley lifting device assembly includes a pulley frame, a hook disposed at the bottom of the pulley frame, a side plate disposed on the pulley frame, and pulleys symmetrically disposed on the side plate via a pivot axis; the fall-prevention wings are symmetrically disposed on both sides of the pulley frame; in use, the steel rope is looped onto the pulleys.

6. The lifting device with anti-overhead function according to claim 5, characterized in that: A punching support is provided between the side plates, and a shearing blade limiting groove is horizontally opened on the punching support; a shearing blade is limited and positioned within the shearing blade limiting groove; an adjusting inclined surface is provided at the end of the shearing blade away from the steel rope; a guide post is also vertically limited and positioned within the punching support, and a wedge block is provided at the lower end of the guide post; the height of the guide post is greater than the upper end face of the side plate; in use, the guide post first contacts the bottom of the crane, thereby descending through the wedge block to push the blade of the shearing blade to extend towards the steel rope, thereby achieving the cutting or severing of the steel rope.

7. The lifting device with anti-overhead function according to claim 6, characterized in that: A spring groove is also provided on the shear blade limiting groove, and a limiting spring is provided in the spring groove to limit the movement; wherein, a limiting block is provided at the bottom of the shear blade to contact the limiting spring, thereby preventing the shear blade from sliding out of the shear blade limiting groove and coming into contact with and rubbing against the steel rope during the non-impact phase.

8. The lifting device with anti-overhead function according to claim 6, characterized in that: A pre-drilled hole is provided at the top of the punching support, which is connected to the shearing blade limiting groove inside. The guide post is adapted to be inserted into the pre-drilled hole, and the inner diameter of the pre-drilled hole is smaller than the length and width of the top surface of the wedge block.

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