Quick unhooking type crane hook device

Abstract

The invention provides a quick unhooking type crane hook device which solves the problem that when a conventional crane is about to incline due to overloading, a hook device is difficult to unhook a load in time, so that the crane is overturned, and the technical scheme is as follows: a hook supporting frame is provided with an automatic unhooking device which comprises a hook supporting disc and an electric control safety lock; the lifting hook supporting disc is arranged between the lifting hook base plate and the lifting hook positioning nut, at least two sets of evenly-distributed outwards-protruding hanging arms are arranged on the outer circumference of the lifting hook supporting disc, at least two sets of evenly-distributed supporting protruding blocks with upper supporting inclined faces are arranged on the inner diameter of the lifting hook base plate, and the supporting protruding blocks and the outwards-protruding hanging arms are in lap joint correspondingly in the circumferential direction. And the electric control bolt lock is provided with a wireless signal receiving module for receiving an unhooking triggering signal of a crane inclination monitoring alarm system. The unhooking device can trigger the unhooking and timely disengagement by receiving an alarm signal of a crane inclination monitoring alarm system, so that rollover caused by dragging of a hoisted object is avoided, and the safety of a crane is protected.

Description

Technical Field

[0001] This invention relates to the field of crane equipment, and in particular to a quick-release crane hook device, suitable for safe lifting operations of engineering cranes. Background Technology

[0002] Currently, cranes are commonly used lifting equipment in engineering projects. Whether it's a truck crane, construction site crane, train crane, or ship crane, operational errors, misjudgments of the weight of the lifted object, or quality issues can inevitably occur during lifting operations, leading to excessive loads and a shift in the crane's center of gravity. This can result in the inability to immediately adjust the crane's center of gravity or detach the lifted object, ultimately causing a rollover or overturning accident, resulting in significant personal injury and property damage. To monitor whether crane equipment will experience rollovers or other abnormal conditions during operation, patent document CN111807241A discloses a crane hydraulic outrigger anti-rollover alarm system. This system uses a pressure transmitter within the control system to monitor the status of the crane's hydraulic outriggers, triggering an alarm when an abnormality occurs. Patent document CN107697820A also discloses a crane anti-rollover system. This system uses gravity and pressure sensors installed on the crane's outriggers, connected to an alarm system via the control system for prevention. A conventional crane hook assembly includes a pulley mechanism supported by a hook support frame and a hook chassis with the hook mounted on it. The hook is secured to the center of the hook chassis via a hook positioning nut at the upper end of the hook shank, preventing it from detaching. Therefore, if the crane tilts while lifting cargo and the anti-tipping system alarms, the hook remains connected to the cargo, preventing the crane operator from quickly releasing the load and potentially causing a rollover accident. Summary of the Invention

[0003] The purpose of this invention is to provide a fast-release crane hook device that solves the problem that conventional cranes are unable to release the load in time when they are about to tilt due to overload, which can lead to overturning and rollover. This device can receive the early warning alarm signal from the crane tilt alarm and quickly and automatically release the load, preventing the crane from overturning and protecting the crane's safety.

[0004] The technical solution adopted in this invention is: a quick-release crane hook device, comprising a pulley mechanism set through a hook support frame and a hook base equipped with a hook. The hook is hooked to the central through hole of the hook base via a hook positioning nut at the upper end of the hook shank. The key technical point is that the hook support frame is equipped with an automatic release device, which includes a hook support plate and an electrically controlled safety lock. The hook support plate is positioned between the hook base and the hook positioning nut. At least two sets of evenly distributed protruding arms are arranged on the outer circumference of the hook support plate, and at least two sets of evenly distributed support protrusions with upper support slopes are arranged on the inner diameter of the hook base. The support protrusions and the protruding arms overlap correspondingly along the circumferential direction. A stop boss is provided at the high position of the hook base. The hook base is formed by the gap between the support bosses and the central through hole, which together form a base release hole for the hook support plate to rotate to the corresponding position. The electric safety lock includes a positioning pin mechanism and an electric bolt lock on the upper surface of the hook base. The positioning pin mechanism is a locking rod with a wedge-shaped locking pin in the middle. The rotating end of the locking rod is rotatably connected to the hook base. The free end of the locking rod is limited by the bolt head of the electric bolt lock. The wedge-shaped locking pin is radially locked and inserted into the locking pin groove on the end face of the outward-protruding hanging arm. The base is provided with an unlocking spring corresponding to the free end of the locking rod. The electric bolt lock is provided with a wireless signal receiving module for receiving the trigger release signal of the crane tilt monitoring alarm system.

[0005] The protruding hanging arm is a support roller set by a support shaft, and the support roller presses against the upper support slope of the support protrusion.

[0006] The outwardly protruding hanging arm is a toothed protrusion, and the toothed protrusion presses against the upper support slope of the support protrusion through the lower support slope.

[0007] The automatic unhooking device is equipped with a hook support plate rotation mechanism that pushes the hook support plate to rotate to the corresponding position of the unhooking hole on the chassis. The hook support plate rotation mechanism is a thrust spring that is set between each set of outward protruding hanging arms and support protrusions to circumferentially push the hook support plate to rotate toward the unhooking hole on the chassis.

[0008] The automatic unhooking device is equipped with a hook support plate rotation mechanism that pushes the hook support plate to rotate to the corresponding position of the unhooking hole on the chassis. The hook support plate rotation mechanism is a worm gear transmission mechanism driven by a motor and threadedly engaged with the outer circumference of the hook support plate to push the hook support plate to rotate toward the unhooking hole on the chassis.

[0009] The hook chassis is equipped with a manual limit pin for the locking rod of the limit positioning locking mechanism.

[0010] A torsion spring is connected between the hook support plate and the hook base plate to push the hook support plate to rotate toward the hook release hole of the base plate.

[0011] The outer end face of the protruding hanging arm is provided with a hook support plate mounting hole for inserting the push rod.

[0012] The hook chassis is equipped with a manual limit pin for the locking rod of the limit positioning locking mechanism.

[0013] The automatic unhooking device is equipped with a hook support plate rotation mechanism that pushes the hook support plate to rotate to the corresponding position of the unhooking hole on the chassis. The hook support plate rotation mechanism includes a worm gear transmission mechanism driven by a motor that engages with the corresponding thread on the outer circumference of the hook support plate to push the hook support plate to rotate toward the unhooking hole on the chassis; a thrust spring that circumferentially pushes the hook support plate toward the unhooking hole on the chassis between each set of protruding hanging arms and support protrusions; the hook chassis is equipped with a manual limit pin for a locking rod of a limit positioning pin mechanism; a torsion spring that pushes the hook support plate to rotate toward the unhooking hole on the chassis is connected between the hook support plate and the hook chassis; and a hook support plate mounting hole for inserting a push rod is provided on the outer end face of the protruding hanging arm.

[0014] The advantages and positive effects of this invention are as follows: Because this invention is equipped with an automatic unhooking device, the supporting protrusions on the hook base and the outer convex arm of the hook support plate are connected in a circumferentially inclined manner. The hook base is formed by the gaps between the supporting protrusions and the central through hole, creating a base unhooking hole for the hook support plate to rotate to the corresponding position. Therefore, the hook base can support the hook support plate, and when the hook support plate rotates to the unhooking hole position under gravity, the hook falls and detaches from the hook base. An electrically controlled safety lock is provided, including a positioning pin mechanism and an electrically controlled bolt lock. The wedge-shaped pin of the positioning pin mechanism is locked and inserted into the locking pin groove on the outer end face of the outer convex arm. The free end of the locking rod is limited by the bolt head of the electrically controlled bolt lock, and the free end of the locking rod on the base is equipped with an unlocking spring. The hook chassis is locked and limited in its support position. A wireless signal receiving module, which receives the trigger signal from the crane tilt monitoring and alarm system, controls the electronically controlled latch lock. This causes the wedge-shaped locking pin to disengage from the locking pin groove, and the hook support plate to disengage from the electronically controlled safety lock. The hook then automatically rotates to the chassis's disengagement hole using gravity, completing the disengagement process. Therefore, by receiving the alarm signal from the crane tilt monitoring and alarm system, the hook can be triggered for timely disengagement, preventing overturning due to the dragging of the suspended object and avoiding losses to personnel and the crane itself. After the suspended object is separated from the crane, not only is a crane accident prevented, but damage to the crane boom and the surrounding environment caused by the crane overturning is also avoided. Furthermore, it prevents injury or death to the crane operator. It is a win-win situation, achieving the goal of sacrificing a pawn to save the king and protecting crane safety. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings.

[0016] Figure 1 This is an exploded view of the hook device according to an embodiment of the present invention. Figure 2 This is a longitudinal sectional view of the hook structure according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the hook support plate structure according to an embodiment of the present invention; Figure 4 yes Figure 3 A schematic diagram of the structure viewed from below; Figure 5 yes Figure 3 A schematic diagram of the AA-direction cross-section structure; Figure 6 Yes, this is a top view of the hook device in the supported state according to an embodiment of the invention. Figure 7 Yes, this is a top view of the hook device in the disengaged state according to an embodiment of the invention. Figure 8 This is a schematic diagram of the supporting state according to another embodiment of the present invention; Figure 9 yes Figure 8 A schematic diagram of the structure in the unhooked state.

[0017] Figure 10 This is an exploded view of the hook device according to Embodiment 3 of the present invention; Figure 11 This is a schematic diagram of the hook support plate structure according to Embodiment 3 of the present invention; Figure 12 yes Figure 10 A longitudinal sectional view of the hook support plate and the hook chassis in the crimped state; Figure 13 This is a top view of the hook device in the supported state according to Embodiment 3 of the present invention; Figure 14 This is a top view of the hook device in the unhooked state according to Embodiment 3 of the present invention.

[0018] The numbers in the diagram are explained as follows: 12 Hook support frame, 13 Pulley mechanism, 14 Protective cover, 15 Positioning nut, 16 Torsion spring, 17 Hook support plate, 18 Hook chassis, 19 Chassis unhooking hole, 20 Hook, 21 Locking rod, 22 Wedge pin, 23 Unlocking spring, 24 Free end of locking rod, 25 Electrically controlled bolt lock, 26 Manual limit bolt, 27 Thrust spring, 28 Motor, 29 Worm gear, 30 Threaded gear, 31 Power supply battery, 171 Outward protruding hanging arm, 172 Locking pin groove, 173 Mounting hole, 174 Lower support slope, 181 Support protrusion, 182 Stop boss, 183 Upper support slope, 251 Pin head. Detailed Implementation

[0019] according to Figures 1-14 Detailed description of the specific structure of the invention, implementation examples Figure 1 and Figure 2 As shown, a quick-release crane hook device is suitable for installation on cranes equipped with a crane tilt monitoring and alarm system. This quick-release crane hook device includes a pulley mechanism 13 mounted via a hook support frame 12, a hook base 18 fitted with a hook 20, and an automatic release device. The hook base 18 is bolted to the lower part of the hook support frame 12, and the hook base has a central through hole. A hook positioning nut 15 for hooking is provided at the upper end of the hook shank of the hook 20. A protective cover 14 can also be provided outside the hook positioning nut to protect the automatic release device.

[0020] The automatic unhooking device includes a hook support plate 17, an electrically controlled safety lock, and a hook base plate that mates with the hook support plate to form a base unhooking hole 19. Among these, for example... Figure 2 As shown, the inner wall of the central through hole of the hook base 18 is provided with a support protrusion 181 with an upper support slope 183. A gap is left between adjacent support protrusions. The hook base is connected by the gap between the support protrusions and the central through hole to form a base unhooking hole 19. A stop protrusion 182 is provided at the high position of the upper support slope of the support protrusion 181. (As shown...) Figures 2 to 5 As shown, the hook support plate 17 is disposed between the hook base plate 18 and the hook positioning nut 15. An outwardly protruding hanging arm 171 is provided on the outer circumference of the hook support plate 17. In this embodiment, the outwardly protruding hanging arm is a toothed protrusion with a lower supporting slope 174, which presses against the upper supporting slope 183 of the supporting protrusion. Figure 6 and Figure 7 As shown, the outer diameter of the hook support plate is smaller than the inner diameter of the circumference of the support protrusion of the hook base. The support protrusion and the outer protruding arm overlap correspondingly in the circumferential direction. The hook base has a bottom hook release hole for the hook support plate to rotate to the corresponding position. The outer protruding arm of the hook support plate rotates along the circumferential direction under the action of gravity and falls to the bottom hook release hole 19 position on the lower part of the support slope. A mounting hole 173 can be provided on the outer end face of the outer protruding arm 171. When the hook support plate is installed in the initial position, the mounting push rod is inserted into the mounting hole. The mounting push rod is used to easily push the hook support plate to rotate to the position supported by the hook base and lock it in place. Then the mounting push rod is pulled out.

[0021] like Figure 6 and Figure 7As shown, the electrically controlled safety lock includes a positioning pin mechanism and an electrically controlled bolt lock 25 disposed on the upper end face of the hook base 18. The positioning pin mechanism is an arc-shaped locking rod 21 that rotates along the arc surface of the hook base. The inner side of the middle part of the locking rod has a wedge-shaped locking pin 22. The rotating end of the locking rod 21 is rotatably connected to the hook base 18 through a rotating shaft. The free end 24 of the locking rod is limited by the bolt head 251 of the electrically controlled bolt lock 25. The wedge-shaped locking pin 22 is radially locked and inserted into the locking pin groove 172 on the outer end face of the outward protruding arm. The hook base 18 is provided with an unlocking spring 23 corresponding to the free end 24 of the locking rod. The root of the unlocking spring is fixed to the outer circumferential end face of the corresponding support protrusion stop boss. The front end of the unlocking spring 23 is perpendicularly abutted against the free end 24 of the locking rod. The bolt head of the electrically controlled bolt lock 25 limits the locking rod so as to prevent the free end of the locking rod from being pushed outward by the unlocking spring. The electrically controlled bolt lock is connected to a wireless signal receiving module and a power supply battery 31. The wireless signal receiving module can be a commercially available electrically controlled bolt lock with a built-in wireless signal receiving module. The locking mechanism of the positioning pin is locked by controlling the extension and retraction of the bolt head. The wireless signal receiving module is used to receive alarm signals from the crane tilt monitoring and alarm system as a trigger signal for unhooking. The wireless signal receiving module can use a wireless remote control, sound wave, or Bluetooth wireless signal communication control method compatible with the crane tilt monitoring and alarm system.

[0022] As a further improvement, at least three sets of supporting protrusions and outwardly protruding hanging arms can be arranged in pairs, evenly distributed along the circumference, such as... Figures 3 to 8 As shown, the support protrusion 171 and the outward-protruding hanging arm 181 are both configured in four groups. The automatic unhooking device is equipped with a hook support plate rotation mechanism that pushes the hook support plate 17 to rotate to the corresponding position of the chassis unhooking hole 19. The hook support plate rotation mechanism is a thrust spring 27 arranged between each group of outward-protruding hanging arms 171 and support protrusion 181 to circumferentially push the hook support plate to rotate toward the chassis unhooking hole. Figure 8 As shown, when the hook chassis and hook support plate are in their initial supported state, the thrust spring 27 is in a compressed state. Because the electronically controlled safety lock is in a locked state, the thrust spring cannot spring out. Figure 9 As shown, when the electronically controlled safety lock is unlocked, the thrust spring 27 releases its thrust, quickly pushing the hook support plate 17 to the position of the chassis disengagement hole, causing the hook support plate and hook to drop and disengage. The hook support plate rotation mechanism can generate thrust instantaneously when the electronically controlled safety lock is unlocked, preventing excessive friction between the protruding arm and the support protrusion from preventing the hook support plate from rotating and avoiding disengagement failure.

[0023] As a further improvement, the supporting protrusions and the outwardly protruding hanging arms are arranged in pairs of two or three sets, evenly distributed along the circumferential direction, such as... Figure 10 and Figure 11As shown, the support protrusion 181 and the outwardly protruding hanging arm 171 are configured as two sets. The automatic unhooking device is equipped with a hook support plate rotation mechanism that pushes the hook support plate 17 to rotate to the position corresponding to the unhooking hole 19 on the chassis. The hook support plate rotation mechanism is a worm gear transmission mechanism driven by a motor 28. The motor 25 is located on the hook chassis 18 away from the support protrusion. The worm gear 29 is connected to the motor drive shaft. The outer circumference of the hook support plate is provided with threaded teeth 30 that mesh with the worm gear 29. The worm gear connected to the motor drive shaft meshes with the corresponding threaded part of the outer circumference of the hook support plate. The motor can be a commercially available wireless control motor with a wireless signal receiving module. The wireless signal receiving module is used to receive the trigger unhooking signal from the crane tilt monitoring and alarm system to activate the motor. When the hook chassis and hook support plate are in their initial supported state, the worm gear 29 and threaded tooth 30 are engaged. When the electrically controlled safety lock receives a trigger signal from the crane tilt monitoring and alarm system via the wireless signal receiving module, it unlocks. Simultaneously, the motor also receives the trigger signal, causing the motor to rotate the worm gear and quickly push the hook support plate to the hook release hole position on the chassis, causing the hook support plate and hook to drop and disengage. The hook support plate rotation mechanism can instantly generate thrust when the electrically controlled safety lock unlocks, preventing excessive friction between the protruding arm and the support protrusion from hindering the rotation of the hook support plate and avoiding disengagement failure.

[0024] As a further improvement, such as Figure 8 and Figure 9 As shown, a manual limit pin 26 is provided on the hook chassis. The safety of the automatic unhooking device can be increased by inserting the manual limit pin into the manual limit socket of the locking rod 21. The manual limit pin is pulled out before the crane starts lifting.

[0025] As a further improvement, such as Figure 3 and Figure 4 As shown, a torsion spring 16 can be connected between the hook support plate 17 and the hook base plate 18 to push the hook support plate to rotate toward the unhooking hole of the base plate. One end of the torsion spring is fixed to the mounting hole of the hook support plate 17, and the other end of the torsion spring is fixed to the mounting hole of the hook base plate 18. It can generate a thrust instantaneously when the electric safety lock is in the unlocked state, assisting in pushing the hook support plate to rotate toward the unhooking hole of the base plate.

[0026] like Figures 10 to 14 As shown, this is a quick-release crane hook device using another type of hook support plate 18. The protruding hanging arm 171 of the hook support plate is a support roller mounted on a support shaft. The support roller presses against the upper support slope of the support protrusion 181. This allows rolling friction to form between the protruding hanging arm 171 and the support protrusion 181, greatly reducing friction and eliminating the need for a thrust spring 27. The locking pin groove 172 and the mounting hole 173 are respectively located at the outer end of the support shaft of the corresponding protruding hanging arm. Other structures are the same as in the aforementioned embodiment.

[0027] Working process and principle: The quick-release crane hook device of the present invention is suitable for use on cranes equipped with a crane tilt monitoring and alarm system. The supporting protrusions of the hook chassis of the automatic release device and the outer protruding arm of the hook support plate are correspondingly overlapped along the circumferential direction in an inclined manner. The hook chassis has a release hole formed by the gaps between the supporting protrusions and the central through hole, allowing the hook support plate to rotate to the corresponding position. Therefore, the hook chassis can support the hook support plate, and when the hook support plate rotates to the release hole position using gravity, the hook falls and detaches from the hook chassis. The device includes a fixed... The electric safety lock of the positioning pin mechanism and the electric control bolt lock utilizes the wedge-shaped pin of the positioning pin mechanism to lock and insert into the locking pin groove on the outer end face of the outward-protruding hanging arm. The free end of the locking rod is limited by the bolt head of the electric control bolt lock, and the chassis has a corresponding unlocking spring at the free end of the locking rod, which can lock and limit the hook chassis to the support position of the hook chassis. The electric control bolt lock is controlled by the wireless signal receiving module that receives the triggering unhooking signal from the crane tilt monitoring alarm system, so that the wedge-shaped pin disengages from the locking pin groove, the hook support plate disengages from the control of the electric safety lock, and automatically rotates to the unhooking hole of the chassis by gravity to complete the unhooking.

[0028] When using this quick-release crane hook device, first remove the manual limit pin of the positioning latch mechanism, then connect the power supply to the electric safety lock. The wireless communication receiving module of the automatic release device receives the release signal and controls the electric control pin lock to act. The electric control pin lock disengages from the limit hook support plate, and the hook chassis rotates to the release hole position on the chassis, causing the hook to detach from the hook device. The crane loses the load it is lifting, restores its center of gravity, and remains stable. Therefore, it can release the hook in time, avoiding overturning caused by the dragging of the lifted object, thus preventing losses to personnel and the crane from tipping over. After the lifted object is separated from the crane, it not only prevents crane accidents but also avoids damage to the crane boom and the surrounding environment caused by the crane tipping over. It also prevents injury or death to the crane operator, achieving two goals at once, thus achieving the purpose of sacrificing a pawn to save the king, and enabling timely and automatic load release to protect the crane's safety.

[0029] In summary, the objective of this invention has been achieved.

Claims

1. A quick-release crane hook device, comprising a pulley mechanism mounted on a hook support frame and a hook base equipped with a hook, wherein the hook is hooked to a central through hole in the hook base via a hook positioning nut at the upper end of the hook shank, characterized in that: The hook support frame is equipped with an automatic unhooking device, which includes a hook support plate and an electrically controlled safety lock. The hook support plate is positioned between the hook base and the hook positioning nut. At least two sets of evenly distributed protruding hanging arms are arranged on the outer circumference of the hook support plate. At least two sets of evenly distributed support protrusions with upper support slopes are arranged on the inner diameter of the hook base. The support protrusions overlap with the protruding hanging arms along the circumferential direction. A stop boss is provided at the high position of the slope of the support protrusion. The hook base is formed by the gaps between the support protrusions and the central through hole, creating a space for the hook support plate. The hook is rotated to the corresponding position through the chassis release hole; the electric safety lock includes a positioning pin mechanism and an electric control pin lock set on the upper end face of the hook chassis. The positioning pin mechanism is a locking rod with a wedge-shaped pin in the middle. The rotating end of the locking rod is rotatably connected to the hook chassis. The free end of the locking rod is limited by the pin head of the electric control pin lock. The wedge-shaped pin is radially locked and inserted into the locking pin groove on the end face of the outward-protruding arm. The chassis is equipped with an unlocking spring corresponding to the free end of the locking rod; the electric control pin lock is equipped with a wireless signal receiving module for receiving the trigger release signal of the crane tilt monitoring alarm system.

2. The quick-release crane hook device according to claim 1, characterized in that: The protruding hanging arm is a support roller set by a support shaft, and the support roller presses against the upper support slope of the support protrusion.

3. The quick-release crane hook device according to claim 1, characterized in that: The outwardly protruding hanging arm is a toothed protrusion, and the toothed protrusion presses against the upper support slope of the support protrusion through the lower support slope.

4. The quick-release crane hook device according to any one of claims 1 to 3, characterized in that: The automatic unhooking device of the supporting protrusion arm is equipped with a hook support plate rotation mechanism that pushes the hook support plate to rotate to the corresponding position of the unhooking hole on the chassis. The hook support plate rotation mechanism is a thrust spring that is set between the outer protruding arm and the supporting protrusion of each set of outer protruding arms to push the hook support plate to rotate toward the unhooking hole on the chassis.

5. The quick-release crane hook device according to any one of claims 1 to 3, characterized in that: The automatic unhooking device of the supporting protrusion arm is equipped with a hook support plate rotation mechanism that pushes the hook support plate to rotate to the corresponding position of the unhooking hole on the chassis. The hook support plate rotation mechanism is a worm gear transmission mechanism driven by a motor and threadedly engaged with the outer circumference of the hook support plate to push the hook support plate to rotate toward the unhooking hole on the chassis.

6. The quick-release crane hook device according to any one of claims 1 to 3, characterized in that: The hook chassis is equipped with a manual limit pin for the locking rod of the limit positioning locking mechanism.

7. The quick-release crane hook device according to any one of claims 1 to 3, characterized in that: A torsion spring is connected between the hook support plate and the hook base plate to push the hook support plate to rotate toward the hook release hole of the base plate.

8. The quick-release crane hook device according to any one of claims 1 to 3, wherein the outer end face of the protruding arm is provided with a hook support plate mounting hole for inserting a push rod.

9. The quick-release crane hook device according to claim 5, wherein the hook chassis is provided with a manual limit pin for the locking rod of the limit positioning locking pin mechanism.

10. The quick-release crane hook device according to claim 2, characterized in that: The automatic unhooking device is equipped with a hook support plate rotation mechanism that pushes the hook support plate to rotate to the corresponding position of the unhooking hole on the chassis. The hook support plate rotation mechanism includes a worm gear transmission mechanism driven by a motor that engages with the corresponding thread on the outer circumference of the hook support plate to push the hook support plate to rotate toward the unhooking hole on the chassis; a thrust spring that circumferentially pushes the hook support plate toward the unhooking hole on the chassis between each set of protruding hanging arms and support protrusions; the hook chassis is equipped with a manual limit pin for a locking rod of a limit positioning pin mechanism; a torsion spring that pushes the hook support plate to rotate toward the unhooking hole on the chassis is connected between the hook support plate and the hook chassis; and a hook support plate mounting hole for inserting a push rod is provided on the outer end face of the protruding hanging arm.

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