A damping mechanism of a rail logistics robot

Abstract

The utility model provides a kind of shock-absorbing mechanism of track logistics robot. The shock-absorbing mechanism of track logistics robot includes box, the bottom of box is fixedly connected with base, the both ends of base are fixedly connected with two mounting plates, the bottom of the side of four mounting plates is fixedly connected with rotating shaft, the outer wall of rotating shaft is rotatably connected with adjusting plate, the one end of adjusting plate is fixedly connected with second mount, the middle part of second mount is fixedly connected with connecting shaft, the one end of connecting shaft is rotatably connected with wheel, the side of adjusting plate is fixedly connected with shock absorber, the one end of shock absorber is fixedly connected with first mount, the bottom of first mount is fixedly connected on the top of mounting plate, the shock-absorbing mechanism of track logistics robot provided by the utility model has the advantages of realizing the up-down adaptive movement of wheel, effectively relieving the local impact caused by uneven track, and keeping the stable operation of robot body.

Description

Technical Field

[0001] This utility model relates to the field of track logistics robots, and in particular to a shock absorption mechanism for track logistics robots. Background Technology

[0002] With the widespread application of intelligent logistics systems in hospitals, factories, warehousing centers and clean rooms, track-mounted logistics robots have become important equipment for efficient and safe material transportation due to their advantages such as high space utilization, fixed running paths and high degree of automation. Track-mounted logistics robots usually run in a loop along preset suspended or ground tracks, undertaking the task of automatically transporting high-value or time-sensitive items such as medicines, samples and parts. Currently, track-based logistics robots commonly use rubber wheels, spring buffer brackets, or simple rubber pads as shock absorption methods. However, these traditional shock absorption methods have obvious technical limitations: First, although rubber wheels have a certain degree of elasticity, their damping performance is poor and they cannot effectively absorb high-frequency vibration energy. Moreover, they are prone to aging and deformation after long-term use. Second, spring-type shock absorption structures are mostly passive rigid connections, lacking stroke limit and damping adjustment functions, and are prone to over-displacement or rebound oscillation under sudden impact. Therefore, it is necessary to provide a new shock absorption mechanism for track logistics robots to solve the above-mentioned technical problems. Utility Model Content

[0003] To solve the above-mentioned technical problems, this utility model provides a shock absorption mechanism for a track logistics robot.

[0004] The shock absorption mechanism of the track logistics robot provided by this utility model includes a housing, a base fixedly connected to the bottom of the housing, two mounting plates fixedly connected to both ends of the base, a rotating shaft fixedly connected to one side of the bottom of the four mounting plates, an adjusting plate rotatably connected to the outer wall of the rotating shaft, a second mounting frame fixedly connected to one end of the adjusting plate, a connecting shaft fixedly connected to the middle of the second mounting frame, a wheel rotatably connected to one end of the connecting shaft, a shock absorber fixedly connected to one side of the adjusting plate, a first mounting frame fixedly connected to one end of the shock absorber, and the bottom of the first mounting frame fixedly connected to the top of the mounting plate.

[0005] Preferably, the shock absorber includes a first mounting rod, a piston rod, a spring, a piston pad, a hydraulic cylinder, and a second mounting rod. One side of the adjusting plate is mounted on one end of the first mounting rod. The other end of the first mounting rod is fixedly connected to one end of the piston rod. The other end of the piston rod is fixedly connected to the inner wall of the piston pad. The outer wall of the piston pad is slidably connected to the inner wall of the hydraulic cylinder. The outer wall of the hydraulic cylinder facing the first mounting rod is fixedly connected to one end of the spring. The other end of the spring is fixedly connected to the outer wall of one end of the first mounting rod. One end of the hydraulic cylinder is fixedly connected to one end of the second mounting rod. The other end of the second mounting rod is mounted on one end of the first mounting bracket.

[0006] Preferably, the inner walls of both the first mounting rod and the second mounting rod are provided with a first universal ball. The outer walls of the two first universal balls are rotatably connected to the inner walls of the first mounting rod and the second mounting rod. The inner wall of one first universal ball is fixedly connected to one side of the adjusting plate, and the inner wall of the other first universal ball is fixedly connected to one end of the first mounting frame.

[0007] Preferably, the top of the second mounting bracket is rotatably connected to a connector, one end of the connector is rotatably connected to a mounting base, and one side of the mounting base is fixedly connected to one side of the mounting plate.

[0008] Preferably, a first mounting sleeve is fixedly connected to the other end of the connecting shaft, a connecting rod is rotatably connected to the inner wall of one end of the first mounting sleeve, a second mounting sleeve is rotatably connected to one end of the connecting rod, and one end of the second mounting sleeve is fixedly connected to one side of the mounting plate.

[0009] Preferably, both ends of the connecting rod are fixedly connected to a second universal ball joint, the outer wall of one of the second universal balls is rotatably connected to the inner wall of one end of the second mounting sleeve, and the outer wall of the other end of the second universal ball joint is rotatably connected to the inner wall of one end of the first mounting sleeve.

[0010] Compared with related technologies, the shock absorption mechanism of the track logistics robot provided by this utility model has the following beneficial effects: An adjusting plate is used as a suspension link, with one end hinged to the mounting plate via a rotating shaft, and the other end connected to the wheel (via a second mounting frame and a connecting shaft). During the robot's movement, when the wheel encounters track joints, bumps, or curves, the adjusting plate can swing slightly around the rotating shaft, achieving adaptive up-and-down movement of the wheel. This effectively alleviates local impacts caused by uneven tracks, maintains stable robot operation, reduces vibration transmission, and significantly improves the robot's operational stability under non-ideal track conditions, making it particularly suitable for track systems with minor misalignments or aging deformation. One end of the shock absorber is connected to the adjusting plate, and the other end is fixed to the top of the mounting plate, forming an inclined support shock absorption structure. When the adjusting plate swings due to wheel bouncing, the shock absorber synchronously compresses or stretches, absorbing vibration kinetic energy and converting it into heat energy for release. This effectively suppresses high-frequency vibrations and transient impacts, protecting the robot's internal precision components (such as control systems, sensors, and transported goods). Attached Figure Description

[0011] Figure 1 A schematic diagram of a preferred embodiment of the shock absorption mechanism for the track logistics robot provided by this utility model; Figure 2 for Figure 1 The diagram shows the structure of the shock-absorbing base. Figure 3 for Figure 1 The diagram shows the structural front end of the shock-absorbing base; Figure 4 for Figure 1 The diagram shows the structure of the shock absorption assembly. Figure 5 for Figure 1 The diagram shown is a structural schematic of the shock absorber. Figure 6 for Figure 1 The diagram shows the structure of the connector. Figure 7 for Figure 1 The diagram shows the structure of the adjustment component. Figure 8 for Figure 1 The diagram shows the structure of the connecting rod. Numbered in the diagram: 1. Housing; 2. Wheel; 3. Base; 4. Mounting plate; 5. Mounting bracket No. 1; 6. Adjusting plate; 7. Mounting bracket No. 2; 8. Mounting rod No. 1; 9. Piston rod; 10. Spring; 11. Piston pad; 12. Hydraulic cylinder; 13. Mounting rod No. 2; 14. Universal ball No. 1; 15. Rotating shaft; 16. Connecting piece; 17. Connecting rod; 18. Universal ball No. 2; 19. Mounting sleeve No. 1; 20. Mounting sleeve No. 2; 21. Mounting seat; 22. Connecting shaft. Detailed Implementation

[0012] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0013] Please refer to the following: Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 as well as Figure 8 ,in, Figure 1 A schematic diagram of a preferred embodiment of the shock absorption mechanism for the track logistics robot provided by this utility model; Figure 2 for Figure 1 The diagram shows the structure of the shock-absorbing base. Figure 3 for Figure 1 The diagram shows the structural front end of the shock-absorbing base; Figure 4 for Figure 1 The diagram shows the structure of the shock absorption assembly. Figure 5 for Figure 1 The diagram shown is a structural schematic of the shock absorber. Figure 6 for Figure 1 The diagram shows the structure of the connector. Figure 7 for Figure 1 The diagram shows the structure of the adjustment component. Figure 8 for Figure 1 The diagram shows the structure of the connecting rod.

[0014] In the specific implementation process, such as Figure 1-5As shown, the shock absorption mechanism for a track-based logistics robot provided by this utility model includes a housing 1. A base 3 is fixedly connected to the bottom of the housing 1. Two mounting plates 4 are fixedly connected to both ends of the base 3. A rotating shaft 15 is fixedly connected to the bottom of one side of each of the four mounting plates 4. An adjusting plate 6 is rotatably connected to the outer wall of the rotating shaft 15. A second mounting bracket 7 is fixedly connected to one end of the adjusting plate 6. A connecting shaft 22 is fixedly connected to the middle of the second mounting bracket 7. A wheel 2 is rotatably connected to one end of the connecting shaft 22. A shock absorber is fixedly connected to one side of the adjusting plate 6. A first mounting bracket 5 is fixedly connected to one end of the shock absorber. The bottom of the first mounting bracket 5 is fixedly connected to the top of the mounting plate 4. The shock absorber includes a first mounting rod 8, a piston rod 9, a spring 10, a piston pad 11, a hydraulic cylinder 12, and a second mounting rod 13. One side of the adjusting plate 6 is mounted to one end of the first mounting rod 8. The other end is fixedly connected to one end of the piston rod 9, and the other end of the piston rod 9 is fixedly connected to the inner wall of the piston pad 11. The outer wall of the piston pad 11 is slidably connected to the inner wall of the oil cylinder 12. The outer wall of the oil cylinder 12 facing the first mounting rod 8 is fixedly connected to one end of the spring 10. The other end of the spring 10 is fixedly connected to the outer wall of one end of the first mounting rod 8. One end of the oil cylinder 12 is fixedly connected to one end of the second mounting rod 13. The other end of the second mounting rod 13 is installed on one end of the first mounting bracket 5. The inner walls of the first mounting rod 8 and the second mounting rod 13 are each provided with a first universal ball 14. The outer walls of the two first universal balls 14 are slidably connected to the inner walls of the first mounting rod 8 and the second mounting rod 13. The inner wall of one first universal ball 14 is fixedly connected to one side of the adjusting plate 6, and the inner wall of the other first universal ball 14 is fixedly connected to one end of the first mounting bracket 5. It should be noted that the shock absorber consists of a hydraulic cylinder 12, a piston rod 9, a piston pad 11, and a spring 10. When the adjusting plate 6 swings due to the bouncing of the wheel 2, it drives the first mounting rod 8 to push the piston rod 9 into the hydraulic cylinder 12. The piston pad 11 slides inside the hydraulic cylinder 12, forcing hydraulic oil to flow through a tiny gap, generating damping force, and converting the vibration kinetic energy into heat energy for release. At the same time, the spring 10 is compressed, storing elastic potential energy, and providing restoring force after the impact to help with rapid reset. This structure combines high damping energy dissipation capacity with elastic buffering. Functionally, it effectively suppresses high-frequency vibration and transient impact, preventing repeated oscillations; one end of spring 10 is connected to the outer wall of cylinder 12, and the other end is connected to the outer wall of mounting rod 8, forming an external parallel spring structure. Under light load or low speed conditions, spring 10 plays a dominant role in buffering and responds sensitively. Under heavy load or severe impact, hydraulic damping plays a major role in preventing over-compression, achieving an adaptive vibration reduction effect of "soft and hard combination", suitable for different loads (such as empty or fully loaded medicine boxes) and track conditions; the inner walls of mounting rod 8 and mounting rod 13 are both equipped with There is a first omnidirectional ball 14, whose inner wall is fixedly connected to the adjustment plate 6 and the first mounting bracket 5. The first omnidirectional ball 14 allows the connecting end to rotate freely at multiple angles in space (pitch, yaw, tilt). When the robot passes through curves, slopes, or track joints, the two ends of the shock absorber can automatically adjust the angle to avoid jamming, stress concentration, or breakage of connecting parts caused by rigid connection, which significantly improves the motion compatibility and structural reliability of the shock absorption system, especially suitable for track systems with complex paths; the outer wall of the first omnidirectional ball 14 is connected to the first mounting rod 8. The inner wall of mounting rod 13 is a rolling contact (using ball bearing or sliding bearing structure), which reduces the sliding friction of traditional hinges and allows the shock absorber to respond quickly even under small vibrations, avoiding the "hysteresis effect" caused by excessive friction, which affects the shock absorption performance; the piston pad 11 and the inner wall of cylinder 12 are in sliding seal fit (using O-ring or lip seal) to prevent hydraulic oil leakage and ensure stable damping force. The cylinder 12 can be filled with high-stability hydraulic oil or damping grease to adapt to a wide temperature range (such as -10℃~60℃) working environment.

[0015] In the specific implementation process, refer to Figure 6-8 As shown, this utility model provides a shock absorption mechanism for a track logistics robot. A connector 16 is rotatably connected to the top of the second mounting frame 7. One end of the connector 16 is rotatably connected to a mounting base 21. One side of the mounting base 21 is fixedly connected to one side of the mounting plate 4. The other end of the connecting shaft 22 is fixedly connected to a first mounting sleeve 19. A connecting rod 17 is rotatably connected to the inner wall of one end of the first mounting sleeve 19. A second mounting sleeve 20 is rotatably connected to one end of the connecting rod 17. One end of the second mounting sleeve 20 is fixedly connected to one side of the mounting plate 4. Two universal balls 18 are fixedly connected to both ends of the connecting rod 17. The outer wall of one universal ball 18 is rotatably connected to the inner wall of one end of the second mounting sleeve 20, and the outer wall of the other end of the universal ball 18 is rotatably connected to the inner wall of one end of the first mounting sleeve 19. It should be noted that a linkage structure consisting of a connecting rod 17, a first mounting sleeve 19, a second mounting sleeve 20, and a second universal ball joint 18 is added between the second mounting bracket 7 and the mounting plate 4, forming a spatial inclined stabilizer bar system. When the wheel 2 experiences lateral displacement or tilting due to uneven track or bending forces, the connecting rod 17 transmits tension or pressure through the second universal ball joints 18 at both ends. This force is then transmitted to the mounting plate 4 via the first mounting sleeve 19 and the second mounting sleeve 20, forming a reverse constraint torque that suppresses excessive lateral sway of the adjusting plate 6 and effectively improves suspension. The rigidity of the hanging system in the lateral and torsional directions prevents the robot from "swaying" or tipping over during operation. The two ends of the connecting rod 17 are connected to the first mounting sleeve 19 and the second mounting sleeve 20 respectively via second universal ball joints 18. The second universal ball joint 18 allows the connecting rod 17 to rotate freely in space (pitch, yaw, roll), adapting to the angle changes of the adjustment plate 6 in vertical, lateral, and combined movements. This avoids stress concentration, jamming, or connector breakage problems caused by traditional rigid connecting rods in complex movements, achieving "rigid force transmission and flexible hinge." The synergistic effect of the "connection" ensures both structural stability and mobility. The outer wall of the second universal ball 18 and the inner wall of the mounting sleeve are in rolling contact (with built-in ball bearings or sliding bearings), which significantly reduces frictional resistance during movement. This allows the connecting rod 17 to respond quickly even under minor vibrations, improving the system's dynamic adjustment capability and ensuring the real-time intervention of the stabilizing mechanism under high-frequency vibrations or transient impacts, avoiding hysteresis effects. The main damping path involves the swinging of the adjusting plate 6 and the energy dissipation of the shock absorbers (hydraulic and spring 10) to achieve vertical buffering. The auxiliary stabilizing path involves the wheels 2. Lateral displacement is controlled by the connecting rod 17, which transmits the constraint force through the second universal ball 18 to suppress tilting. The two work in parallel to deal with vertical impact and lateral disturbance respectively, forming a multi-directional collaborative damping mechanism to comprehensively improve the stability of operation. The top of the second mounting bracket 7 is rotatably connected to the mounting seat 21 fixed to the mounting plate 4 through the connector 16. This rotatable connection point serves as an auxiliary guide fulcrum for the movement of the adjustment plate 6, restricting its movement trajectory and preventing torsional deformation. Together with the rotating shaft 15, it forms a "double fulcrum constraint" to improve the structural stability of the adjustment plate 6 under complex stress.

[0016] The working principle of this utility model is as follows: When the wheel 2 travels to the track joint, weld point, or local protrusion, it is subjected to an upward impact force. The wheel 2 pushes the second mounting bracket 7 upward through the connecting shaft 22, which in turn drives the adjusting plate 6 to swing clockwise (or counterclockwise) around the rotating shaft 15. The swing of the adjusting plate 6 stretches or compresses the shock absorber. The specific process is as follows: The first mounting rod 8 moves with the adjusting plate 6, pushing the piston rod 9 to drive the piston pad 11 into the oil cylinder 12. The hydraulic oil flows through the tiny gap under the compression of the piston pad 11, generating a damping force and consuming the vibration. The kinetic energy is absorbed and dissipated by the external spring 10, which is compressed to store elastic potential energy, thus preventing vibration from being transmitted to the box 1 and the transported items inside. When the robot enters a curve or experiences lateral acceleration due to load eccentricity, the wheel 2 tends to shift outward, and the adjusting plate 6 tilts or twists laterally. At this time, the connecting rod 17 functions through the second universal ball joints 18 at both ends: the first mounting sleeve 19 moves with the second mounting bracket 7, pulling the connecting rod 17, which transmits the pulling force to the second universal ball joint 18 fixed to the mounting plate 4. Installing sleeve 20 creates a reverse constraint torque, suppressing excessive lateral sway of adjusting plate 6, effectively improving the lateral stiffness and anti-roll capability of the suspension system, and preventing robot swaying or derailment; under complex working conditions (such as curves and joints), wheel 2 simultaneously bears vertical impact and lateral disturbance. At this time, the main shock absorption system (shock absorber) and the auxiliary stabilization system (connecting rod 17 and second universal ball 18) work together: the shock absorber absorbs vertical energy through hydraulic damping and spring 10 reset, the connecting rod 17 flexibly transmits force through the second universal ball 18 to provide lateral constraint, and the first universal ball... 14 allows the shock absorber to freely adjust its angle at both ends to avoid rigid interference. The second omnidirectional ball 18 ensures that the connecting rod 17 always transmits force smoothly during multi-directional movement, achieving a multi-dimensional shock absorption effect of "vertical buffering, lateral stability and angle self-adaptation". When the wheel 2 passes the obstacle, the external excitation disappears, the elastic potential energy stored in the spring 10 is released, pushing the piston pad 11 back, the shock absorber returns to its original length, the tension of the connecting rod 17 decreases, the adjusting plate 6 returns to a horizontal posture under the constraints of gravity and structure, and the omnidirectional ball automatically adjusts to a free state to prepare for the next vibration response.

[0017] The shock absorption mechanism of this rail logistics robot has the following advantages: The main shock absorption system, consisting of an adjusting plate 6 and shock absorbers (hydraulic and spring 10), effectively absorbs the vertical impact and high-frequency vibration generated by the wheels 2 during track joints, bulges, or start-stop processes. Hydraulic damping dissipates energy, and spring 12 provides elastic buffering, forming a "soft and hard" combined shock absorption mode. This significantly reduces the degree of vibration transmission to the housing 1, improves transport stability, and protects delicate items from vibration damage. A first universal ball joint 14 is installed at both ends of the shock absorber, allowing the first mounting rod 8 to connect with the second mounting rod. Rod 13 rotates freely in space. When the robot passes through curves, ramps, or uneven sections of the track, the shock absorber can automatically adjust its angle to avoid jamming, deformation, or breakage caused by rigid connections. Similarly, the second universal ball joints 18 at both ends of connecting rod 17 are also flexibly hinged to ensure smooth transmission of lateral stability force. The inclined stabilizer system composed of connecting rod 17, first mounting sleeve 19, and second mounting sleeve 20 generates a constraint torque on connecting rod 17 when the wheel 2 undergoes lateral displacement or the robot enters a curve, suppressing the lateral sway of the adjusting plate 6. This effectively prevents the risk of "snake-like swaying" or tipping during robot operation, improves lateral stability and anti-tilt capability, and ensures safe operation at high speeds or on curves. The main system, the shock absorber, is responsible for vertical buffering and energy dissipation, while the auxiliary system, the connecting rod 17, is responsible for lateral constraint and attitude stability. The two systems work in parallel to deal with disturbances in different directions, forming a multi-directional collaborative shock absorption mechanism. The second mounting frame 7 is rotatably connected to the mounting base 21 fixed to the mounting plate 4 via the connector 16, forming an auxiliary rotation fulcrum, which together with the main rotating shaft 15 forms a "double fulcrum constraint". The guide plate 6 moves along a predetermined trajectory to prevent torsional deformation or uneven wear of wheel 2 caused by single-point force, thereby improving the smoothness and guiding accuracy of the suspension system and reducing mechanical wear. The spring 10 is externally connected in parallel to both ends of the hydraulic cylinder 12 to form a composite damping system of "external spring 10 and internal hydraulic system". Under light load, the spring 10 plays a dominant role in buffering and responds sensitively. Under heavy load or severe impact, the hydraulic damping plays a major role in preventing over-compression. It can automatically adjust the damping stiffness according to different loads (empty or full load) to achieve "adaptive damping", which is suitable for various transportation tasks.

[0018] The circuits and controls involved in this utility model are all existing technologies, and will not be described in detail here.

[0019] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made based on the content of this utility model specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A shock absorption mechanism for a track-based logistics robot, comprising a housing (1), wherein a base (3) is fixedly connected to the bottom of the housing (1), and two mounting plates (4) are fixedly connected to both ends of the base (3), characterized in that, A rotating shaft (15) is fixedly connected to one side bottom of the four mounting plates (4). An adjusting plate (6) is rotatably connected to the outer wall of the rotating shaft (15). A second mounting bracket (7) is fixedly connected to one end of the adjusting plate (6). A connecting shaft (22) is fixedly connected to the middle of the second mounting bracket (7). A wheel (2) is rotatably connected to one end of the connecting shaft (22). A shock absorber is fixedly connected to one side of the adjusting plate (6). A first mounting bracket (5) is fixedly connected to one end of the shock absorber. The bottom of the first mounting bracket (5) is fixedly connected to the top of the mounting plate (4).

2. The shock absorption mechanism of the track logistics robot according to claim 1, characterized in that, The shock absorber includes a first mounting rod (8), a piston rod (9), a spring (10), a piston pad (11), a cylinder (12), and a second mounting rod (13). One side of the adjusting plate (6) is mounted on one end of the first mounting rod (8). The other end of the first mounting rod (8) is fixedly connected to one end of the piston rod (9). The other end of the piston rod (9) is fixedly connected to the inner wall of the piston pad (11). The outer wall of the piston pad (11) is slidably connected to the inner wall of the cylinder (12). The outer wall of the cylinder (12) facing the first mounting rod (8) is fixedly connected to one end of the spring (10). The other end of the spring (10) is fixedly connected to the outer wall of one end of the first mounting rod (8). One end of the cylinder (12) is fixedly connected to one end of the second mounting rod (13). The other end of the second mounting rod (13) is mounted on one end of the first mounting bracket (5).

3. The shock absorption mechanism of the track logistics robot according to claim 2, characterized in that, The inner walls of the first mounting rod (8) and the second mounting rod (13) are each provided with a first universal ball (14). The outer walls of the two first universal balls (14) are rolled to the inner walls of the first mounting rod (8) and the second mounting rod (13). The inner wall of one first universal ball (14) is fixedly connected to one side of the adjusting plate (6), and the inner wall of the other first universal ball (14) is fixedly connected to one end of the first mounting bracket (5).

4. The shock absorption mechanism of the track logistics robot according to claim 3, characterized in that, The top of the second mounting bracket (7) is rotatably connected to a connector (16), one end of which is rotatably connected to a mounting base (21), and one side of the mounting base (21) is fixedly connected to one side of the mounting plate (4).

5. The shock absorption mechanism of the track logistics robot according to claim 4, characterized in that, The other end of the connecting shaft (22) is fixedly connected to a first mounting sleeve (19). A connecting rod (17) is slidably connected to the inner wall of one end of the first mounting sleeve (19). A second mounting sleeve (20) is slidably connected to one end of the connecting rod (17). One end of the second mounting sleeve (20) is fixedly connected to one side of the mounting plate (4).

6. The shock absorption mechanism of the track logistics robot according to claim 5, characterized in that, Both ends of the connecting rod (17) are fixedly connected to a second universal ball (18). The outer wall of one of the second universal balls (18) is rolled to the inner wall of one end of the second mounting sleeve (20), and the outer wall of the other end of the second universal ball (18) is rolled to the inner wall of one end of the first mounting sleeve (19).

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