Crane and using method thereof

Abstract

A crane comprises a hoisting mechanism, a rotating mechanism used for driving the hoisting mechanism to rotate and a hoisting mechanism in transmission connection with the hoisting mechanism, the hoisting mechanism comprises a hydraulic driving assembly, a reversible motor and an energy storage unit, and the hydraulic driving assembly and the reversible motor are in transmission connection with the hoisting mechanism. The lifting mechanisms are used for jointly or independently providing power for the lifting mechanisms; the energy storage unit is connected with the reversible motor. The hydraulic driving assembly and the reversible motor are in independent transmission connection with the hoisting mechanism, the reversible motor can be used as a generator under specific working conditions, potential energy of a heavy object is converted into electric energy, the electric energy is stored in the energy storage unit, energy is effectively recycled and reused, waste of potential energy in the heavy object descending process of a traditional crane is avoided, and the cost is reduced. And the energy utilization efficiency is greatly improved, so that the energy consumption is reduced, and powerful support is provided for sustainable operation.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering machinery, and in particular to a crane and a method for using the crane. Background Art

[0002] In many fields such as engineering construction, logistics and transportation, cranes are indispensable and important equipment, and are widely used in heavy object lifting and loading and unloading operations. In the field of traditional cranes, hydraulic systems have long occupied the position of the main power source. Taking the common mobile crane as an example, its lifting mechanism, slewing mechanism and luffing mechanism mostly rely on hydraulic motors for driving. The hydraulic drive method certainly has significant advantages such as large output torque and smooth transmission process. However, in terms of lifting operations, traditional cranes face serious energy waste problems. When the weight is lowered, the large amount of potential energy contained in it cannot be effectively recycled. On the contrary, the hydraulic system also needs to consume additional energy to control the descending speed of the weight, which leads to a low energy utilization rate in the entire lifting operation process. In addition, in order to ensure that the single rope tension of the wire rope during the lifting operation can meet the requirements, the lifting reducer of the traditional crane is usually equipped with a larger reduction ratio. Although this design guarantees the safety of the lifting operation to a certain extent, it has greatly limited the running speed when no-load, making it impossible to further increase the maximum speed when no-load. Especially during the lifting and lowering process of no-load, due to the speed limitation, the entire lifting operation cycle takes a long time, which seriously affects the overall operation efficiency of the crane. Summary of the invention

[0003] The purpose of the present invention is to provide a crane and a method for using the same, wherein a lifting mechanism is independently connected to a reversible motor through a hydraulic drive assembly, and the reversible motor can be used as a generator under specific working conditions to convert the potential energy of a heavy object into electrical energy, which is stored in an energy storage unit, thereby achieving effective recovery and reuse of energy, avoiding the waste of potential energy of a traditional crane during the process of lowering heavy objects, greatly improving energy utilization efficiency, thereby reducing energy consumption, and providing strong support for sustainable operations.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows: The present invention provides a crane, comprising a lifting mechanism for lifting objects, a slewing mechanism for carrying the lifting mechanism and driving the lifting mechanism to rotate, and a hoisting mechanism transmission-connected to the lifting mechanism for providing power to the lifting mechanism, wherein the hoisting mechanism comprises a hydraulic drive assembly, a reversible motor and an energy storage unit, wherein the hydraulic drive assembly and the reversible motor are respectively transmission-connected to the lifting mechanism for providing power to the lifting mechanism jointly or independently; the energy storage unit is connected to the reversible motor.

[0005] Specifically, in this embodiment, the lifting mechanism includes a boom, a pulley installed at an end of the boom, a traction rope wound around the pulley, and a hook installed at the end of the traction rope.

[0006] Specifically, in this embodiment, the lifting mechanism also includes a bracket, a drum rotatably mounted on the bracket, and a bearing seat for connecting the drum and the bracket. The other end of the traction rope is wound around the drum, and the drum is used to drive the traction rope to pull the hook by rotating.

[0007] Specifically, in this embodiment, the hoisting mechanism also includes a transmission shaft passing through the inside of the drum, the hydraulic drive assembly and the reversible motor are respectively connected to the transmission shaft, and the reversible motor is installed at the end of the transmission shaft passing through the bracket.

[0008] Specifically, in this embodiment, the hoisting mechanism further includes a transmission transmission connected between the reversible motor and the transmission shaft, and a clutch transmission connected between the transmission and the transmission shaft.

[0009] Specifically, in this embodiment, the hydraulic drive assembly includes a hydraulic motor and a first reducer transmission-connected between the hydraulic motor and the transmission shaft.

[0010] Specifically, in this embodiment, the reversible motor, the transmission, the clutch, the hydraulic motor and the first reducer are all mounted on the bracket.

[0011] Specifically, in this embodiment, the slewing mechanism includes a bearing platform for bearing the lifting mechanism, a second reducer transmission-connected to the bearing platform for driving the lifting mechanism to rotate, and the second reducer is transmission-connected to the reversible motor.

[0012] Specifically, in this embodiment, a variable-length mechanism for controlling the lifting height is also included and is installed between the supporting platform and the boom.

[0013] A method for using a crane, the method for using a crane being implemented by the crane described in any one of the embodiments, the method for using a crane comprising: S1. Estimate the weight of the object to be lifted; S2. Determine, based on the estimation result of S1, whether the weight of the object to be lifted is within a preset first weight range or a second weight range; S3. If the weight of the object to be lifted is within the first weight range, the hydraulic drive assembly is used to independently provide power to the lifting mechanism to lift or lower the object to be lifted; if the weight of the object to be lifted is within the second weight range, the hydraulic drive assembly and the reversible motor are used together to provide power to the lifting mechanism to lift or lower the object to be lifted.

[0014] The present invention provides a crane and a method for using the crane, including a lifting mechanism for lifting objects, a slewing mechanism for carrying the lifting mechanism and driving the lifting mechanism to rotate, and a winch mechanism connected to the lifting mechanism for providing power to the lifting mechanism, wherein the winch mechanism includes a hydraulic drive assembly, a reversible motor, and an energy storage unit, wherein the hydraulic drive assembly and the reversible motor are respectively connected to the lifting mechanism for providing power to the lifting mechanism together or independently of each other; and the energy storage unit is connected to the reversible motor. In terms of energy saving and consumption reduction, the lifting mechanism is connected to the reversible motor through the hydraulic drive assembly and the reversible motor respectively and independently, and the reversible motor can be used as a generator under specific working conditions (such as lowering medium and heavy loads), converting the potential energy of the heavy object into electrical energy, realizing effective energy recovery and reuse, avoiding the waste of potential energy of traditional cranes during the lowering of heavy objects, greatly improving energy utilization efficiency, thereby reducing energy consumption, and providing strong support for sustainable operations. In terms of improving operating efficiency, the hydraulic-electric dual-power drive lifting mechanism ensures that the lifting mechanism has sufficient maximum output torque while achieving a significant increase in loaded speed and light load maximum speed, effectively shortening the no-load lifting and lowering time, and ultimately reducing the time required for a single lifting operation cycle, greatly improving the overall operating efficiency and enabling the crane to complete more lifting tasks in a shorter time. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 A schematic diagram of the overall structure of a crane provided in one embodiment of the present invention.

[0017] Figure 2 for Figure 1 The structural schematic diagram of the hoisting mechanism of the crane is shown.

[0018] Figure 3 for Figure 1 The schematic diagram of the structure of the slewing mechanism of the crane is shown.

[0019] Figure 4 A flow chart of a crane lifting method provided in one embodiment of the present invention.

[0020] In the figure: 1. lifting mechanism; 11. boom; 12. pulley; 13. traction rope; 14. hook; 15. bracket; 16. drum; 17. bearing seat; 2. hoisting mechanism; 21. hydraulic motor; 22. first reducer; 23. transmission shaft; 24. reversible motor; 25. transmission; 26. clutch; 27. energy storage unit; 3. slewing mechanism; 31. bearing platform; 32. second reducer; 4. luffing mechanism. DETAILED DESCRIPTION

[0021] The specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the description of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In the description of the present invention, unless otherwise clearly specified and limited, the terms "set", "install", "connection" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0022] The directions or positional relationships indicated by terms such as “upper”, “lower”, “left”, “right”, “front”, “back”, “top”, “bottom”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships commonly placed when the invention is used. They are only for the convenience of description and simplified description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore should not be understood as a limitation on the invention.

[0023] The terms "first", "second", "third" and the like are merely used to distinguish elements of similar nature, and do not indicate or imply relative importance or a particular order.

[0024] The terms "comprises," "comprising," or any other variations thereof, are intended to cover a non-exclusive inclusion of the elements listed and may also include additional elements not expressly listed.

[0025] like Figures 1 to 3As shown, a crane provided by a preferred embodiment of the present invention comprises a lifting mechanism 1 for lifting objects, a slewing mechanism 3 for carrying the lifting mechanism 1 and driving the lifting mechanism 1 to rotate, and a hoisting mechanism 2 which is transmission-connected to the lifting mechanism 1 and is used to provide power for the lifting mechanism 1, wherein the hoisting mechanism 2 comprises a hydraulic drive assembly, a reversible motor 24 and an energy storage unit 27 connected to the reversible motor 24, the hydraulic drive assembly and the reversible motor 24 are transmission-connected to the lifting mechanism 1 respectively, and are used to provide power to the lifting mechanism 1 jointly or independently of each other; the reversible motor 24 is also used to convert the potential energy released when the lifting object is lowered into electrical energy; the energy storage unit 27 is connected to the reversible motor 24, and is used to store the electrical energy generated by the reversible motor 24 when the lifting object is lowered, and to provide the stored electrical energy to the reversible motor 24 when the reversible motor 24 provides power for the lifting mechanism 1. In terms of energy saving and consumption reduction, the lifting mechanism 1 is connected to the reversible motor 24 through independent transmission respectively through the hydraulic drive component, and the reversible motor 24 can be used as a generator under certain working conditions (such as lowering medium and heavy loads), converting the potential energy of the heavy object into electrical energy, realizing effective energy recovery and reuse, avoiding the waste of potential energy in the process of lowering heavy objects in traditional cranes, greatly improving energy utilization efficiency, thereby reducing energy consumption, and providing strong support for sustainable operations. In terms of improving operating efficiency, by means of hydraulic-electric dual-power driving the lifting mechanism 1, while ensuring that the lifting mechanism 1 has sufficient maximum output torque, the load speed and light load maximum speed are significantly improved, effectively shortening the no-load lifting and lowering time, and ultimately reducing the time required for a single lifting operation cycle, greatly improving the overall operating efficiency, and enabling the crane to complete more lifting tasks in a shorter time.

[0026] Specifically, the lifting mechanism 1 is fixed to the slewing mechanism 3 by bolts, pins and other connectors, so that it can realize slewing motion as the slewing mechanism 3 rotates, expanding the working range of the crane, and enabling the crane to perform lifting operations in any direction within a certain radius; the hydraulic drive component and the reversible motor 24 work together in lifting heavier objects, reasonably distribute power according to the instructions of the control system, and jointly provide the required torque. In addition, during the process of lowering heavy objects, the reversible motor 24 can be switched to the power generation mode, converting the potential energy of the lowered heavy objects into electrical energy and transmitting it to the energy storage unit 27, which stores the electrical energy and waits to be called when electrical energy is needed in subsequent crane operations (such as lifting operations, slewing mechanism driving, etc.), realizing energy recovery, effectively improving energy utilization, and reducing the energy consumption of the crane.

[0027] Specifically, the lifting mechanism 1 includes a boom 11, a pulley 12 installed at the end of the boom 11, a traction rope 13 wound on the pulley 12, and a hook 14 installed at the end of the traction rope 13. The pulley 12 is connected to the bearing at the end of the boom 11 to ensure that the pulley 12 can rotate around the axis. The function of the pulley 12 is to change the direction of the traction rope 13 so that the traction rope 13 can be wound along the direction of the boom 11 to achieve the vertical lifting movement of the hook 14; the traction rope 13 is a key component for transmitting power, which converts the rotational power generated by the hoisting mechanism 2 into a linear lifting movement of the hook 14; the hook 14 is tightly combined with the traction rope 13 to form a whole, which is used to directly contact the hoisted object and bear the weight of the object.

[0028] Specifically, the lifting mechanism 1 further includes a bracket 15, a drum 16 rotatably mounted on the bracket 15, the other end of the traction rope 13 is wound on the drum 16, and the drum 16 is used to drive the traction rope 13 to pull the hook 14 by rotating. The drum 16 is mounted on the bracket 15 through a bearing seat 17.

[0029] In this embodiment, the hoisting mechanism 2 further includes a transmission shaft 23 passing through the drum 16, and the hydraulic transmission assembly and the reversible motor 24 are respectively connected to the transmission shaft 23. The reversible motor 24 is installed at the end of the transmission shaft 23 passing through the bracket 15, and the hydraulic motor 21 converts the pressure energy generated by the hydraulic system into mechanical energy, and transmits the torque to the transmission shaft 23 through the connection with the transmission shaft 23. The transmission shaft 23 then transmits the power to the drum 16, so that the drum 16 rotates to realize the retraction and release of the traction rope 13, thereby controlling the lifting and lowering of the hook 14.

[0030] Specifically, the reversible motor 24 brings more flexibility and energy-saving potential to the lifting mechanism 1. When lifting light loads, the reversible motor 24 can work alone, adjust the appropriate speed and torque through the transmission 25, quickly and efficiently complete the light load lifting task, and improve work efficiency. When lifting medium and heavy loads, the reversible motor 24 works in coordination with the hydraulic mechanism to reasonably distribute power according to the instructions of the control system and the actual working conditions, and jointly provide the required torque. During the lowering of heavy objects, the reversible motor 24 can be switched to the power generation mode. At this time, the electromagnetic clutch 26 is closed, and the motor reverses under the action of the gravity of the heavy object, converting the potential energy of the heavy object into electrical energy, which is transmitted and stored through the transmission shaft 23, the transmission 25 and other components to achieve energy recovery.

[0031] In this embodiment, the hoisting mechanism 2 also includes a transmission 25 that is transmission-connected between the reversible motor 24 and the transmission shaft 23, and a clutch 26 that is transmission-connected between the transmission 25 and the transmission shaft 23. The output shaft of the reversible motor 24 is connected to the input shaft of the transmission 25 through a coupling. It is used to adjust the speed and torque output by the reversible motor 24 according to different operating conditions. The output shaft of the transmission 25 is connected to the active part of the clutch 26 through a spline. It can ensure that the torque output by the transmission 25 is accurately and stably transmitted to the clutch 26, and the synchronous rotation of the two is maintained during the transmission process, which plays a key role in power connection and disconnection, and realizes flexible control of power transmission between the reversible motor 24 and the transmission shaft 23.

[0032] Specifically, a through hole is opened on the bearing seat 17 for the transmission shaft 23 to pass through. During installation, the transmission shaft 23 can be smoothly inserted along the axial direction of the through hole, and the assembly of the entire winch mechanism 2 can be completed by connecting with other components (such as the reversible motor 24, the drum 16, etc.).

[0033] In this embodiment, the hydraulic drive assembly includes a hydraulic motor 21 and a first reducer 22 that is transmission-connected between the hydraulic motor 21 and the input shaft. The reversible motor 24, the transmission 25, the clutch 26, the hydraulic motor 21 and the first reducer 22 are all mounted on the bracket 15. The reversible motor 24, the transmission 25, the clutch 26, the hydraulic motor 21 and the first reducer 22 are usually fixed to the bracket 15 by bolt connection.

[0034] In this embodiment, the slewing mechanism 3 includes a bearing platform 31 for bearing the lifting mechanism 1, a second reducer 32 which is transmission-connected to the bearing platform 31 and is used to drive the lifting mechanism 1 to rotate, and the second reducer 32 is transmission-connected to the reversible motor 24. During the operation of the crane, by controlling the forward and reverse rotation and speed of the reversible motor 24 and the speed regulating function of the second reducer 32, the bearing platform 31 can be rotated at any angle in the horizontal plane, so that the hoisted objects can be accurately hoisted to the designated position.

[0035] In this embodiment, a variable amplitude mechanism 4 for controlling the lifting height is also included and is installed between the bearing platform 31 and the boom 11. It is mainly used to change the amplitude of the boom 11, that is, the angle between the boom 11 and the horizontal plane, so as to control the lifting height and working radius.

[0036] like Figure 4 As shown, another aspect of the present application also provides a method for using a crane, which can be implemented using the crane of the aforementioned embodiment, and the method includes: S1. Estimate the weight of the object to be lifted; S2. Determine, based on the estimation result of step S1, whether the weight of the object to be lifted is within a preset first weight range or a second weight range; S3. If the weight of the object to be lifted is within the first weight range, the hydraulic drive assembly is used to independently provide power to the lifting mechanism (1) to lift or lower the object to be lifted; if the weight of the object to be lifted is within the second weight range, the hydraulic drive assembly and the reversible motor (24) are used together to provide power to the lifting mechanism (1) to lift or lower the object to be lifted.

[0037] When lifting objects in the first weight range, the clutch 26 is opened, and the hydraulic drive component independently provides power to the lifting mechanism 1; when lowering, the clutch 26 is opened, and the hydraulic drive component independently controls the lowering speed of the lifting mechanism 1.

[0038] When lifting objects in the second weight range, the clutch 26 is closed, and the hydraulic drive assembly and the reversible motor 24 jointly provide power to the lifting mechanism 1; when lowering, the clutch 26 is closed, and the lowering potential energy of the lift object is converted into electrical energy by the reversible motor 24, and the hydraulic drive assembly and the reversible motor 24 jointly control the lowering speed of the lifting mechanism 1.

[0039] The first weight range is relatively light. When lifting the hoisted object, the hydraulic drive assembly steadily drives the drum 16 of the lifting mechanism 1 to rotate, thereby achieving smooth lifting of the hook 14 and the hoisted object. When lowering the hoisted object, the hydraulic drive assembly uses its adjustable hydraulic control circuit to independently control the lowering speed of the lifting mechanism 1.

[0040] The second weight range belongs to the medium and heavy load level. When lifting the hoisted object, the clutch 26 is closed. In this way, the hydraulic drive component and the reversible motor 24 can jointly provide power to the lifting mechanism 1. When lowering the hoisted object, after the clutch 26 is closed, the potential energy contained in the lowering of the hoisted object is converted into electrical energy by the reversible motor 24 and stored in the matching energy storage unit 27 for use in subsequent crane operations. At the same time, the hydraulic drive component and the reversible motor 24 jointly control the lowering speed of the lifting mechanism 1.

[0041] A crane and a method for using the crane provided by the present invention include a lifting mechanism 1 for lifting objects, a slewing mechanism 3 for carrying the lifting mechanism 1 and driving the lifting mechanism 1 to rotate, and a hoisting mechanism 2 that is transmission-connected to the lifting mechanism 1 and is used to provide power to the lifting mechanism 1. The hoisting mechanism 2 includes a hydraulic drive component, a reversible motor 24 and an energy storage unit 27. The hydraulic drive component and the reversible motor 24 are transmission-connected to the lifting mechanism 1 respectively, and are used to provide power to the lifting mechanism 1 together or independently of each other; the reversible motor 24 is also used to convert the potential energy released when the lifted objects are lowered into electrical energy; the energy storage unit 27 is connected to the reversible motor 24, and is used to store the electrical energy generated by the reversible motor 24 when the lifted objects are lowered, and to provide the stored electrical energy to the reversible motor 24 when the reversible motor 24 provides power to the lifting mechanism 1. In terms of energy saving and consumption reduction, the lifting mechanism 1 is independently connected to the reversible motor 24 through the hydraulic drive component, and the reversible motor 24 can be used as a generator under specific working conditions (such as lowering medium and heavy loads), converting the potential energy of the heavy object into electrical energy, thereby achieving effective energy recovery and reuse, avoiding the waste of potential energy of traditional cranes during the lowering of heavy objects, greatly improving energy utilization efficiency, thereby reducing energy consumption, and providing strong support for sustainable operations.

[0042] In terms of improving operating efficiency, by using the hydraulic-electric dual-power drive lifting mechanism 1, while ensuring that the lifting mechanism 1 has sufficient maximum output torque, the loaded speed and the maximum light-load speed are significantly improved, effectively shortening the no-load lifting and lowering time, and ultimately reducing the time required for a single lifting operation cycle, greatly improving the overall operating efficiency, and enabling the crane to complete more lifting tasks in a shorter time.

[0043] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A crane, characterized in that: The invention comprises a lifting mechanism (1) for lifting objects, a slewing mechanism (3) for carrying the lifting mechanism (1) and driving the lifting mechanism (1) to slew, and a hoisting mechanism (2) drivingly connected to the lifting mechanism (1) for providing power to the lifting mechanism (1), wherein the hoisting mechanism (2) comprises a hydraulic drive component, a reversible motor (24) and an energy storage unit (27), wherein the hydraulic drive component and the reversible motor (24) are respectively drivingly connected to the lifting mechanism (1) for jointly or independently providing power to the lifting mechanism (1); and the energy storage unit (27) is connected to the reversible motor (24).

2. The crane according to claim 1, characterized in that: The lifting mechanism (1) comprises a suspension arm (11), a pulley (12) mounted at the end of the suspension arm (11), a traction rope (13) wound around the pulley (12), and a hook (14) mounted at the end of the traction rope (13).

3. The crane according to claim 2, characterized in that: The lifting mechanism (1) also includes a bracket (15), a drum (16) rotatably mounted on the bracket (15), and a bearing seat (17) for connecting the drum (16) and the bracket (15), the other end of the traction rope (13) is wound around the drum (16), and the drum (16) is used to drive the traction rope (13) to pull the hook (14) by rotating.

4. The crane according to claim 3, characterized in that: The hoisting mechanism (2) further comprises a transmission shaft (23) passing through the interior of the winding drum (16); the hydraulic drive assembly and the reversible motor (24) are respectively connected to the transmission shaft (23) in transmission connection; and the reversible motor (24) is mounted on an end of the transmission shaft (23) passing through the bracket (15).

5. The crane according to claim 4, characterized in that: The hoisting mechanism (2) further comprises a transmission (25) transmission-connected between the reversible motor (24) and the transmission shaft (23), and a clutch (26) transmission-connected between the transmission (25) and the transmission shaft (23).

6. The crane according to claim 5, characterized in that: The hydraulic drive assembly comprises a hydraulic motor (21) and a first reducer (22) drivingly connected between the hydraulic motor (21) and the transmission shaft (23).

7. The crane according to claim 6, characterized in that The reversible motor (24), the transmission (25), the clutch (26), the hydraulic motor (21) and the first reducer (22) are all mounted on the bracket (15).

8. The crane according to claim 2, characterized in that: The slewing mechanism (3) comprises a bearing platform (31) for bearing the lifting mechanism (1), a second reducer (32) drivingly connected to the bearing platform (31) for driving the lifting mechanism (1) to slew, and the second reducer (32) drivingly connected to the reversible motor (24).

9. The crane according to claim 8, characterized in that It also includes a variable amplitude mechanism (4) installed between the bearing platform (31) and the suspension arm (11) and used for controlling the lifting height.

10. A method for using a crane, wherein the crane hoisting method is implemented by the crane according to any one of claims 1 to 9, and the crane hoisting method comprises: S1. Estimate the weight of the object to be lifted; S2. Determine, based on the estimation result of S1, whether the weight of the object to be lifted is within a preset first weight range or a second weight range; S3. If the weight of the object to be lifted is within the first weight range, the hydraulic drive assembly is used to independently provide power to the lifting mechanism (1) to lift or lower the object to be lifted; if the weight of the object to be lifted is within the second weight range, the hydraulic drive assembly and the reversible motor (24) are used together to provide power to the lifting mechanism (1) to lift or lower the object to be lifted.

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