Shipborne cantilever crane integrating slewing bearing and braking and slewing braking method

Abstract

The invention discloses a ship-borne cantilever crane integrating slewing bearing and braking and a slewing braking method. The ship-borne cantilever crane comprises a stand column, a cantilever, a hoist crane arranged on the cantilever and a slewing driving mechanism used for driving the cantilever to rotate around the stand column. A rotation and brake integrated mechanism is arranged between the top end of the stand column and the root of the cantilever; the rotary braking integrated mechanism comprises an integrated rotary braking device, and the integrated rotary braking device has two working states: a rotary supporting state: the integrated rotary braking device is in an unlocking state, and the cantilever is allowed to rotate around the stand column under the driving of the rotary driving mechanism; in the rotation braking state, the integrated rotation braking device is in the locking state, braking torque is applied to the cantilever, and the cantilever is braked relative to the stand column. According to the invention, a slewing bearing function and a braking function are integrated on a mechanical structure, so that the problems of slow slewing braking response, inaccurate parking and large inertial impact of the shipborne cantilever crane are solved.

Description

Technical Field

[0001] This invention belongs to the technical field of hoisting equipment on ship decks, and particularly relates to a shipborne cantilever crane integrating slewing bearing and braking and a slewing braking method. Background Technology

[0002] Traditional shipboard cantilever cranes typically employ a separate design for their slewing mechanism and braking system. The slewing function is usually achieved by an independent slewing reducer or slewing bearing, while the braking function largely relies on a brake installed at the output of the drive motor. This separate design has inherent drawbacks: the brake acts on the high-speed motor shaft, requiring the entire transmission chain (such as a reducer) to amplify the braking torque and transmit it to the low-speed, high-inertia cantilever. This results in transmission gaps and elastic deformation, leading to slow braking response and hysteresis, and also causing torque loss during transmission. Furthermore, under dynamic conditions such as ship swaying and load swinging, relying solely on motor shaft braking is insufficient to quickly and effectively suppress the cantilever's enormous rotational inertia, easily causing brake slippage, inaccurate positioning, or increased swaying, affecting operational efficiency and safety. Summary of the Invention

[0003] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the present invention provides a shipborne cantilever crane and a slewing braking method that integrates slewing bearing and braking. By integrating the slewing bearing function and braking function into a single mechanical structure, the invention solves the problems of slow slewing braking response, inaccurate stopping position, and large inertial impact of shipborne cantilever cranes.

[0004] Technical solution: To achieve the above objectives, the present invention provides a shipborne cantilever crane integrating slewing bearing and braking, comprising a column, a cantilever, a hoist mounted on the cantilever, and a slewing drive mechanism for driving the cantilever to rotate around the column, wherein an integrated slewing braking mechanism is provided between the top of the column and the root of the cantilever.

[0005] The integrated slewing braking mechanism includes an integrated slewing braking device, which has two operating states:

[0006] Slewing support state: The integrated slewing brake device is in the unlocked state, allowing the cantilever to rotate around the column under the drive of the slewing drive mechanism;

[0007] Slewing braking state: The integrated slewing braking device is in a locked state, applying a braking torque to the cantilever, causing it to be braked relative to the column.

[0008] Furthermore, the integrated slewing braking device includes a central slewing bearing assembly, at least one peripheral rolling support assembly, and a brake;

[0009] The cantilever is fixedly connected to the root of the arm shaft, the central slewing bearing assembly is coaxially fixed to the top of the column, and the arm shaft is rotatably supported in the central slewing bearing assembly.

[0010] The upper end of the central slewing bearing assembly is coaxially fixedly connected to a lower fixed cover plate, and the upper movable cover plate is coaxially fixedly connected to the arm shaft.

[0011] The peripheral rolling support assembly is disposed between the lower fixed cover plate and the upper movable cover plate, and its rolling element makes rolling contact with the bottom surface of the upper movable cover plate;

[0012] The brake is correspondingly disposed at the peripheral rolling support assembly, and is used to selectively unlock or lock the rotation of the peripheral rolling support assembly;

[0013] When the brake is unlocked, the cantilever rotates, causing the upper movable cover to move, which in turn drives the rolling element to rotate; when the brake is locked, the rolling element is braked, and the cantilever is braked by the static friction generated between it and the upper movable cover.

[0014] Furthermore, there are multiple peripheral rolling support components, which are evenly distributed along the circumference of the lower fixed cover plate.

[0015] Furthermore, the peripheral rolling support assembly includes a shaft frame fixed to the top surface of the lower fixed cover plate, a support shaft mounted on the shaft frame along the horizontal radial direction of the lower fixed cover plate, and the rolling element fixedly sleeved on the support shaft.

[0016] Furthermore, the number of rolling elements is multiple, arranged axially along the support shaft and radially outward along the lower fixed cover plate, with the arrangement density of the rolling elements gradually increasing.

[0017] Furthermore, the rolling element is a roller or a cylinder.

[0018] Furthermore, the brake is a holding brake mounted on the lower fixed cover plate via a brake bracket; one end of the support shaft extends axially to form a brake extension shaft with an increased diameter, and the brake extension shaft extends into the working cavity of the holding brake.

[0019] Furthermore, the central slewing bearing assembly includes a bearing housing coaxially fixed to the top of the column, a bearing installed in the bearing housing, and a lower fixed cover plate that covers the upper end of the bearing housing to axially limit the bearing.

[0020] The lower part of the arm shaft mates with the inner ring of the bearing and is axially fixed by washers and lock nuts;

[0021] The upper port of the bearing housing is also provided with a bearing center cover for radially limiting the arm shaft.

[0022] Furthermore, the hoist is mounted on the cantilever via a traveling trolley; the slewing drive mechanism is mounted on a support arm fixed at the root of the cantilever.

[0023] A slewing braking method for a shipborne cantilever crane integrating a slewing bearing and a brake includes the following steps:

[0024] When it is necessary to stop the cantilever in rotational motion, perform a synchronous compound braking operation:

[0025] Step 1: Activate the brake of the integrated slewing brake device to lock the rolling elements of the outer rolling support assembly. The direct mechanical friction between the locked rolling elements and the upper movable cover plate that rotates with the cantilever generates the main braking torque acting on the root of the cantilever to resist its inertia, thus braking the cantilever.

[0026] Step 2: While activating the brake, control the output torque direction of the slewing drive mechanism to change to the opposite direction of the cantilever's current slewing direction, so as to generate a reverse auxiliary braking torque to assist in deceleration;

[0027] By simultaneously executing the first and second steps, the direct mechanical braking of the integrated rotary braking device works in conjunction with the motor braking of the rotary drive mechanism to bring the cantilever to a stop at the target position.

[0028] Beneficial Effects: This invention integrates support, rotation, and braking functions through a slewing and braking integrated mechanism, improving structural compactness and overall rigidity. The brake acts directly on the peripheral rolling support components, allowing the braking torque to be transmitted to the cantilever root without lag via static friction, completely avoiding the response lag of traditional transmission chains and achieving rapid and efficient braking response. Combined with synchronous composite braking control, the combined effect of mechanical braking and electric drive braking effectively suppresses inertial impact and load sway, ensuring smoothness and positioning accuracy of slewing stop under heavy load conditions. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0030] Figure 2 This is a half-sectional structural diagram showing the location of the integrated rotary braking device of the present invention.

[0031] Figure 3 This is a top view schematic diagram of the integrated slewing braking device. Detailed Implementation

[0032] The invention will now be further described with reference to the accompanying drawings.

[0033] In traditional marine cantilever cranes, the slewing mechanism and braking system are usually separate. The slewing function is handled by a slewing reducer or large bearings, while the braking function relies on a separate brake mounted on the output shaft of the drive motor. This layout results in the braking torque needing to travel through a long transmission chain (such as gears and shafts) to reach the cantilever, leading to problems such as response delay, energy loss, and inaccurate positioning due to transmission backlash.

[0034] To address the aforementioned problems, this invention structurally integrates and functionally couples the support component that enables rotational motion with the component that enables braking, forming a single functional module that combines support, rotation, and braking capabilities. The specific solution is as follows: Figure 1 and Figure 2 As shown, a shipborne cantilever crane integrating a slewing bearing and braking system includes a column 1, a cantilever 2, a hoist 3 mounted on the cantilever 2, and a slewing drive mechanism 4 for driving the cantilever 2 to rotate around the column 1. An integrated slewing braking mechanism 5 is provided between the top of the column 1 and the root of the cantilever 2. The integrated slewing braking mechanism 5 includes an integrated slewing braking device 6, which has two operating states:

[0035] Rotational support state: The integrated rotary braking device 6 is in the unlocked state, allowing the cantilever 2 to rotate around the column 1 under the drive of the rotary drive mechanism 4.

[0036] Rotation braking state: The integrated rotation braking device 6 is in a locked state, applying a braking torque to the cantilever 2, causing it to be braked relative to the column 1.

[0037] The integrated rotary braking device 6 of the present invention has two distinct working states, which are switched by an external control signal (such as an electrical signal): When the integrated rotary braking device 6 receives an unlocking command, its internal mechanism allows relative rotation between the cantilever and its supporting base (column 1). At this time, the power output by the rotary drive mechanism 4 can smoothly drive the cantilever 2 to rotate 360° around the column 1 for material hoisting and positioning. When the cantilever 2 needs to stop, the integrated rotary braking device 6 receives a locking command, and its internal mechanism quickly acts to apply a braking torque to the cantilever 2 in the opposite direction of rotation. This torque acts directly between the rotating root of the cantilever 2 and the fixed top of the column 1, thereby efficiently and directly resisting the inertia of the cantilever 2 and the load, and making it brake quickly relative to the column 1.

[0038] Therefore, this invention moves the braking function's execution point from the traditional drive motor shaft end to the source position of the cantilever rotation motion, greatly shortening the transmission path of the braking torque and eliminating the lag, elastic deformation, and energy loss caused by the transmission chain, ensuring fast, precise, and efficient braking. Simultaneously, the integrated design makes the structure more compact, reducing exposed couplings, long shafts, and other components, thus improving reliability in the confined spaces and humid, salt-spray environments of ships.

[0039] The integrated rotary braking device includes a central rotary support assembly 7, at least one peripheral rolling support assembly 8, and a brake 9; an arm shaft 20 is fixedly connected to the root of the cantilever 2; the central rotary support assembly 7 is coaxially fixed to the top of the column 1; the arm shaft 20 is rotatably supported within the central rotary support assembly 7; a lower fixed cover plate 71 is coaxially fixedly connected to the upper end of the central rotary support assembly 7; an upper movable cover plate 21 is coaxially fixedly connected to the arm shaft 20; the peripheral rolling support assembly 8 is disposed between the lower fixed cover plate 71 and the upper movable cover plate 9. Between the cover plates 21, the rolling element 81 of the upper movable cover plate 21 rolls in contact with the bottom surface of the upper movable cover plate 21; the brake 9 is correspondingly disposed at the peripheral rolling support assembly 8, used to selectively unlock or lock the rotation of the peripheral rolling support assembly 8; wherein, when the brake 9 is unlocked, the cantilever 2 rotates, driving the upper movable cover plate 21 to move, thereby driving the rolling element 81 to rotate; when the brake 9 is locked, the rolling element 81 is braked, and the cantilever 2 is braked by the static friction force generated between it and the upper movable cover plate 21. The working process and principle of the integrated rotary braking device are as follows:

[0040] Rotation (Unlocking) Process: When the brake 9 is in the unlocked state, it does not obstruct the rotation of the peripheral rolling support assembly 8. At this time, the rotation drive mechanism 4 drives the cantilever 2 and arm shaft 20 to rotate, causing the upper movable cover plate 21 to rotate as well. Since the bottom surface of the upper movable cover plate 21 is in rolling contact with the rolling element 81, the friction is minimal, so the upper movable cover plate 21 can easily roll over the rolling element 81. At this time, the peripheral rolling support assembly 8 mainly plays an auxiliary support role, sharing part of the overturning moment and ensuring smooth rotation. The central slewing bearing assembly 7 bears the main load and provides precise guidance.

[0041] Braking (Locking) Process: When braking is required, brake 9 receives a signal and quickly switches to the locked state, locking the rolling elements 81 of the outer rolling support assembly 8 so that they cannot rotate. At this time, the motion state between the bottom surface of the upper movable cover plate 21, which is still trying to continue rotating under inertia, and the locked, stationary rolling elements 81, instantly changes from rolling friction to sliding friction, and quickly reaches static friction. Since the static friction coefficient is much greater than the rolling friction coefficient, and the locking force provided by brake 9 is large enough, a huge static friction force is generated between the upper movable cover plate 21 and the rolling elements 81. The direction of this static friction force is opposite to the direction of movement of the upper movable cover plate 21 (i.e., cantilever 2), thus forming a strong braking torque acting on the root of cantilever 2, forcing cantilever 2 to decelerate rapidly until it stops.

[0042] The ingenuity of the above implementation lies in the functional synergy and friction mode transformation. The central slewing bearing assembly 7 is dedicated to high-precision, high-rigidity main load bearing and slewing guidance, ensuring the inherent reliability of the equipment. The peripheral rolling support assembly 8 has a dual function: during rotation, it acts as a low-resistance auxiliary bearing; during braking, it is converted into a high-efficiency friction brake disc by being locked. The brake 9 only needs to apply force to a relatively lightweight peripheral assembly to apply an amplified braking torque to the cantilever 2 through leverage (friction arm). This design separates high-precision load bearing from high-friction braking, avoiding thermal deformation and wear caused by the large-diameter brake disc directly participating in precision rotation, while achieving excellent results such as fast braking response, large torque, and no interference with the main rotation accuracy.

[0043] More specifically, such as Figure 2 and Figure 3 As shown, there are multiple peripheral rolling support components 8, evenly distributed circumferentially along the lower fixed cover plate 71. When the cantilever crane rotates under load, the direction of the overturning moment acting on the rotation center changes due to the change in load position. Multiple evenly distributed support points ensure that the upper movable cover plate 21 receives balanced support force at any angle, avoiding cover plate deformation or rotation jamming due to uneven support. During braking, the evenly distributed braking points ensure that the braking torque acts evenly on the entire circumference of the upper movable cover plate 21, generating smooth, impact-free rotational resistance, effectively preventing braking vibration or one-sided wear, and improving the smoothness, stability, and reliability of the entire rotation braking process (whether in the support or braking phase).

[0044] The peripheral rolling support assembly 8 includes a shaft bracket 82 fixed to the top surface of the lower fixed cover plate 71, a support shaft 83 mounted radially along the lower fixed cover plate 71 on the shaft bracket 82, and a rolling element 81 fixedly sleeved on the support shaft 83. The support shaft 83 is arranged radially so that the rotation axis of the rolling element 81 intersects perpendicularly with the rotation center (arm shaft 20 axis), ensuring pure rolling contact (or near-pure rolling) between the rolling element 81 and the bottom surface of the upper movable cover plate 21, minimizing friction. The shaft bracket 82 provides a stable mounting base, ensuring that the support shaft 83 will not skew under radial pressure. The fixed sleeve connection ensures that braking torque can be transmitted from the brake 9 to the rolling element 81 without loss.

[0045] When the cantilever crane is under load, the pressure on different radial positions of the upper movable cover plate 21 is different. Generally, due to the lever effect, the position farther away from the center of rotation may bear a greater equivalent pressure (especially when bearing overturning moment). Furthermore, during rotation braking, the linear velocity at different radii on the upper movable cover plate 21 is different, with a higher linear velocity at the outer edge. This results in a longer friction path traversed in the same amount of time, leading to more intense heat generation and wear. In this invention, as... Figure 2 or Figure 3 As shown, there are multiple rolling elements 81 arranged axially along the support shaft 83 and radially outward along the lower fixed cover plate 71, with the density of the rolling elements 81 gradually increasing. Therefore, in areas expected to bear greater pressure and higher frictional work at the outer edge, arranging more rolling elements can achieve load and wear distribution. This non-uniform density distribution is an active load-matching arrangement, which makes the stress and working conditions of all rolling elements 81 more balanced, avoiding premature failure of local rolling elements, thereby extending the service life of the entire friction pair and helping to maintain long-term stable braking performance.

[0046] The rolling element 81 is a roller or a cylinder.

[0047] Rollers refer to cylindrical or drum-shaped objects with a small width-to-diameter ratio. Their advantage is that the contact with the plane is approximately line contact, resulting in extremely low rolling resistance. They are very suitable for high-speed applications or applications requiring extremely low starting torque.

[0048] Rollers are cylindrical objects with a larger length-to-diameter ratio. Their contact with a flat surface is closer to surface contact or long-line contact, thus resulting in a greater load-bearing capacity. In high-load, low-to-medium speed applications such as heavy-duty cantilever cranes, rollers can provide a larger load-bearing area and stronger impact resistance while ensuring smooth rolling.

[0049] The roller or roller scheme offers flexibility, allowing selection of the most suitable rolling element type 81 based on specific load, speed, and operating conditions to achieve a better balance between low-friction rotation and high load capacity / high braking reliability.

[0050] More specifically, the brake 9 is a holding brake mounted on the lower fixed cover plate 71 via a brake bracket 91; one end of the support shaft 83 extends axially to form a brake extension shaft 84 with an increased diameter, and the brake extension shaft 84 extends into the working cavity of the holding brake.

[0051] like Figure 2 As shown, the central slewing bearing assembly 7 includes a bearing housing 72 coaxially fixed to the top of the column 1, a bearing 73 installed in the bearing housing 72, and a lower fixed cover plate 71 covering the upper end of the bearing housing 72 to axially limit the bearing 73; the lower part of the arm shaft 20 mates with the inner ring of the bearing 73 and is axially fixed by a washer 75 and a locking nut 76; the upper port of the bearing housing 72 is also provided with a bearing center cover 74 for radially limiting the arm shaft 20.

[0052] like Figure 1 As shown, the hoist 3 is mounted on the cantilever 2 via the traveling trolley 10; the rotary drive mechanism 4 is mounted on the support arm 11 fixed at the root of the cantilever 2.

[0053] A slewing braking method for a shipborne cantilever crane integrating a slewing bearing and a brake includes the following steps:

[0054] When it is necessary to stop the cantilever 2, which is in rotational motion, a synchronous compound braking operation is performed:

[0055] Step 1: Immediately (or according to the predetermined instruction) activate the brake 9 of the integrated rotary brake device 6. The brake 9 actuates, locking the rolling element 81 of the peripheral rolling support assembly 8, stopping its rotation. Thus, through the direct mechanical friction between the locked rolling element 81 and the upper movable cover plate 21 that rotates with the cantilever 2, a main braking torque is formed at the root of the cantilever 2 to resist its inertia, thereby braking the cantilever 2.

[0056] Step 2: At the same time as the brake 9 is activated (or within a very short, almost negligible electronic delay), the control system sends a command to the slewing drive mechanism 4 to change the output torque direction of the slewing drive mechanism 4 to the opposite direction to the current slewing direction of the cantilever 2. At this time, the motor enters the reverse drive mode, which generates a reverse auxiliary braking torque to assist in deceleration.

[0057] By simultaneously executing the first and second steps, the direct mechanical braking of the integrated rotary braking device 6 and the motor braking of the rotary drive mechanism 4 work together to stop the cantilever 2 at the target position.

[0058] Mechanical braking (the first step) provides the speed and force basis for braking response, quickly establishing strong braking force and effectively suppressing initial inertia. Electric braking (the second step) provides controllability and smoothness of the braking process, allowing for fine-tuning of the deceleration curve, compensating for potential shocks from pure mechanical braking, and assisting in achieving precise positioning. The synchronized operation of both is faster and more reliable than simple electric motor braking (low torque, potential slippage), and smoother and more precise than simple mechanical braking (potential shocks). This method is particularly suitable for shipboard operations with heavy loads, large inertia, and requiring smooth and precise stopping, effectively solving the problems of long braking distances, large stopping sway, and significant impact on transmission components associated with traditional methods.

[0059] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A shipborne cantilever crane integrating slewing bearing and braking, comprising a column (1), a cantilever (2), a hoist (3) mounted on the cantilever (2), and a slewing drive mechanism (4) for driving the cantilever (2) to rotate around the column (1), characterized in that: A rotary braking integrated mechanism (5) is provided between the top of the column (1) and the root of the cantilever (2). The integrated slewing braking mechanism (5) includes an integrated slewing braking device (6), which has two working states: Rotary support state: The integrated rotary brake device (6) is in the unlocked state, allowing the cantilever (2) to rotate around the column (1) under the drive of the rotary drive mechanism (4); Rotation braking state: The integrated rotation braking device (6) is in a locked state, applying a braking torque to the cantilever (2) so that it is braked relative to the column (1).

2. The shipborne cantilever crane integrating slewing bearing and brake according to claim 1, characterized in that: The integrated slewing braking device includes a central slewing bearing assembly (7), at least one peripheral rolling support assembly (8), and a brake (9). The cantilever (2) is fixedly connected to the root of the arm shaft (20), the central slewing bearing assembly (7) is coaxially fixed to the top of the column (1), and the arm shaft (20) is rotatably supported in the central slewing bearing assembly (7). The upper end of the central slewing bearing assembly (7) is coaxially fixedly connected to a lower fixed cover plate (71), and the upper arm shaft (20) is coaxially fixedly connected to an upper movable cover plate (21). The peripheral rolling support assembly (8) is disposed between the lower fixed cover plate (71) and the upper movable cover plate (21), and its rolling body (81) makes rolling contact with the bottom surface of the upper movable cover plate (21). The brake (9) is correspondingly disposed at the peripheral rolling support assembly (8) and is used to selectively unlock or lock the rotation of the peripheral rolling support assembly (8); When the brake (9) is unlocked, the cantilever (2) rotates and drives the upper movable cover plate (21) to move, thereby driving the rolling body (81) to rotate; when the brake (9) is locked, the rolling body (81) is braked, and the cantilever (2) is braked by the static friction force generated between it and the upper movable cover plate (21).

3. A shipborne cantilever crane integrating a slewing bearing and brake according to claim 2, characterized in that: The number of the peripheral rolling support components (8) is multiple, and they are evenly distributed along the circumference of the lower fixed cover plate (71).

4. A shipborne cantilever crane integrating a slewing bearing and a brake as described in claim 2 or 3, characterized in that: The peripheral rolling support assembly (8) includes a shaft frame (82) fixed to the top surface of the lower fixed cover plate (71), a support shaft (83) mounted on the shaft frame (82) along the horizontal radial direction of the lower fixed cover plate (71), and a rolling element (81) fixedly sleeved on the support shaft (83).

5. A shipborne cantilever crane integrating a slewing bearing and a brake according to claim 4, characterized in that: The number of the rolling elements (81) is multiple, arranged along the axial direction of the support shaft (83) and radially outward along the lower fixed cover plate (71), and the arrangement density of the rolling elements (81) gradually increases.

6. A shipborne cantilever crane integrating a slewing bearing and a brake according to claim 4, characterized in that: The rolling element (81) is a roller or a cylinder.

7. A shipborne cantilever crane integrating a slewing bearing and brake according to claim 4, characterized in that: The brake (9) is a holding brake mounted on the lower fixed cover plate (71) via a brake frame (91); one end of the support shaft (83) extends axially to form a brake extension shaft (84) with an increased diameter, and the brake extension shaft (84) extends into the working cavity of the holding brake.

8. A shipborne cantilever crane integrating a slewing bearing and brake according to claim 2, characterized in that: The central slewing bearing assembly (7) includes a bearing housing (72) coaxially fixed to the top of the column (1), a bearing (73) installed in the bearing housing (72), and a lower fixed cover plate (71) covering the upper end of the bearing housing (72) to axially limit the bearing (73). The lower part of the arm shaft (20) mates with the inner ring of the bearing (73) and is axially fixed by a washer (75) and a lock nut (76); The upper port of the bearing housing (72) is also provided with a bearing center cover (74) for radially limiting the arm shaft (20).

9. A shipborne cantilever crane integrating a slewing bearing and brake according to claim 1, characterized in that: The hoist (3) is mounted on the cantilever (2) via a traveling trolley (10); the rotary drive mechanism (4) is mounted on the support arm (11) fixed at the root of the cantilever (2).

10. The slewing braking method for a shipborne cantilever crane integrating a slewing bearing and a brake according to claim 2, characterized in that: Includes the following steps: When it is necessary to stop the cantilever (2) in rotational motion, perform a synchronous compound braking operation: Step 1: Activate the brake (9) of the integrated rotary brake device (6) to lock the rolling elements (81) of the outer rolling support assembly (8). The direct mechanical friction between the locked rolling elements (81) and the upper movable cover plate (21) that rotates with the cantilever (2) forms the main braking torque acting on the root of the cantilever (2) to resist its inertia, thus forming a braking effect on the cantilever (2). Step 2: At the same time as activating the brake (9), control the output torque direction of the slewing drive mechanism (4) to change to the opposite direction of the current slewing direction of the cantilever (2), so that it generates a reverse auxiliary braking torque to assist in deceleration; By simultaneously executing the first and second steps, the direct mechanical braking of the integrated rotary braking device (6) and the motor braking of the rotary drive mechanism (4) work together to stop the cantilever (2) at the target position.

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