An aircraft maintenance ladder and method

Abstract

This invention discloses an aircraft maintenance ladder and method, including a walking ladder assembly. The walking ladder assembly includes a base frame, with a step fixedly connected to the upper side of the base frame; a lifting assembly is fixedly connected to the step, and the lifting assembly is threadedly connected to an adjusting assembly, which is fixedly connected to two sets of maintenance components; each maintenance component includes an L-plate, which has a first adjusting groove and a second adjusting groove; a first motor is fixedly connected to the L-plate, and the output shaft of the first motor passes through the L-plate and is fixedly connected to a first screw; the first screw is threadedly connected to a protruding plate, which is nested within the first adjusting groove. This invention relates to the field of aircraft maintenance technology, specifically to an aircraft maintenance ladder and method. The technical problem this invention aims to solve is to provide an aircraft maintenance ladder and method that facilitates the maintenance of the aircraft's vertical tail.

Description

Technical Field

[0001] This invention relates to the field of aircraft maintenance technology, and more specifically, to an aircraft maintenance ladder and method. Background Technology

[0002] An airplane is an aircraft with wings and one or more engines, propelled by its own power, and capable of gliding through the atmosphere where its density is greater than that of air. If the density of an aircraft is less than that of air, it is a balloon or an airship. If it lacks a power plant and can only glide through the air, it is called a glider. If the wings of an aircraft are not fixed and generate lift through wing rotation, it is a helicopter or a rotorcraft. Fixed-wing aircraft are the most common type of aircraft. Power sources include piston engines, turboprop engines, turbofan engines, or rocket engines, etc.

[0003] Maintenance ladders are required for aircraft maintenance. Existing maintenance ladders are generally limited in function, only assisting personnel in accessing the aircraft for repairs. Currently, there is a lack of maintenance ladders capable of automated control, allowing for the spraying or application of liquids to the vertical stabilizer for maintenance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an aircraft maintenance ladder and method to facilitate the maintenance of the aircraft vertical tail.

[0005] The present invention achieves its objective by employing the following technical solution:

[0006] An aircraft maintenance ladder and method, comprising a walking ladder assembly, characterized in that: the walking ladder assembly includes a base frame, with a step fixedly connected to the upper side of the base frame; the step is fixedly connected to a lifting assembly, the lifting assembly is threadedly connected to an adjusting assembly, and the adjusting assembly is fixedly connected to two sets of maintenance components; each maintenance component includes an L-plate, the L-plate being provided with a first adjusting groove and a second adjusting groove, the L-plate being fixedly connected to a first motor, the output shaft of the first motor passing through the L-plate and fixedly connected to a first screw, the first screw being threadedly connected to a protruding plate, the protruding plate being nested within the first adjusting groove; the L-plate is fixedly connected to a second motor, the output shaft of the second motor passing through the L-plate and fixedly connected to a second screw, the second screw being threadedly connected to a T-block, and so on. The T-block is nested within the second adjusting groove; the convex plate is fixedly connected to the slide groove, a first sensor is fixedly connected to one side of the slide groove, a second sensor is fixedly connected within the slide groove, and the convex plate is fixedly connected to the fixed shaft; the T-block is fixedly connected to the first straight groove, the fixed shaft is rotatably connected to the V-rod, the V-rod is fixedly connected to the first round shaft, the first round shaft is disposed within the first straight groove, the V-rod is fixedly connected to the second round shaft, and the second round shaft is disposed within the second straight groove; a slide bar is nested within the slide groove, the slide bar is fixedly connected to the second straight groove, the T-block is fixedly connected to the second mounting block, the second mounting block is fixedly connected to the second maintenance mechanism, the slide bar is fixedly connected to the first mounting block, and the first mounting block is fixedly connected to the first maintenance mechanism.

[0007] As a further limitation of this technical solution, the lifting assembly includes a lifting motor and a lifting guide rod, the step is fixedly connected to the lifting motor and the lifting guide rod, and the output shaft of the lifting motor is fixedly connected to the lifting screw.

[0008] As a further limitation of this technical solution, the adjustment assembly includes a lifting T-plate, a lifting screw threadedly connected to the lifting T-plate, lifting guide rods passing through the corresponding lifting T-plates, a vertical plate fixedly connected to the lifting T-plate, two sets of symmetrical guide plates fixedly connected to the vertical plate, a guide crossbar fixedly connected to each guide plate, a horizontal motor fixedly connected to the vertical plate, a horizontal screw fixedly connected to the output shaft of the horizontal motor, a horizontal slider threadedly connected to the horizontal screw, a vertical rod fixedly connected to the horizontal slider, symmetrical guide crossbars passing through the symmetrical vertical rods, Z-frames fixedly connected to the symmetrical vertical rods, and corresponding L-plates fixedly connected to the symmetrical Z-frames.

[0009] As a further limitation of this technical solution, the vertical plate bearing is connected to a gear, the gear meshes with a symmetrical rack, the symmetrical racks are respectively fixedly connected to guide mounting rods, the symmetrical guide mounting rods pass through the corresponding guide plates, and the symmetrical guide mounting rods are respectively fixedly connected to the corresponding vertical rods.

[0010] As a further limitation of this technical solution, the first maintenance mechanism and the second maintenance mechanism include a spraying structure, a spraying mechanism and a coating structure.

[0011] As a further limitation of this technical solution, mounting seats for wheels are fixedly connected to the four lower corners of the base frame.

[0012] As a further limitation of this technical solution, the wheel has a self-locking function.

[0013] A method for using an aircraft maintenance ladder, characterized by comprising the following steps:

[0014] S1: Select the first maintenance agency and the second maintenance agency according to the maintenance content;

[0015] S2: Push this device to match the position of the vertical tail, and use the first sensor to detect the position of the first maintenance mechanism and the trailing edge of the aircraft vertical tail to match the positions of the two.

[0016] S3: Based on the tail model, the controller intelligently controls the rotation of the horizontal motor to ensure that the distance between the maintenance components on both sides and the tail is appropriate;

[0017] S4: The controller intelligently controls the rotation of the first motor to ensure that the first and second maintenance mechanisms are properly positioned with the tail; when the first and second maintenance mechanisms are made of sponge, they need to be pre-soaked to ensure contact with the tail.

[0018] S5: The controller intelligently controls the second motor to reciprocate, enabling the first maintenance mechanism and the second maintenance mechanism to reciprocate and move to maintain the aircraft. The second sensor detects the position of the slide bar to determine whether the vertical tail has been fully maintained in the forward and backward direction. At the same time, the controller intelligently controls the lifting motor to rotate, so that the maintenance components can perform maintenance on the vertical tail from top to bottom.

[0019] As a further limitation of this technical solution, the movement of the transverse motor is intelligently controlled by the controller to achieve the first positioning of the entire maintenance component. The rotation of the first motor is intelligently controlled by the controller, and the second sensor is used to perform a second, more accurate positioning, which drives the second mounting blocks on both sides to extend to the appropriate position. This not only achieves more accurate positioning, but also limits the extreme position of the movement of the first mounting block.

[0020] As a further limitation of this technical solution, by adopting the design of connecting round shafts to both ends of the V-rod and setting the round shafts in the straight groove, after the first motor is positioned, the second motor drives the first maintenance mechanism to move laterally while the second maintenance mechanism moves longitudinally, thereby realizing the maintenance of the tail.

[0021] Compared with the prior art, the advantages and positive effects of the present invention are:

[0022] 1. This device achieves the first positioning of the entire maintenance component by controlling the movement of the horizontal motor. By controlling the rotation of the first motor, a second, more accurate positioning is achieved in conjunction with the second sensor, which drives the second mounting blocks on both sides to extend to the appropriate position. This not only achieves more accurate positioning but also limits the extreme position of the movement of the first mounting block.

[0023] 2. This device, by using a design where the two ends of the V-rod are respectively connected to round shafts and the round shafts are set in straight grooves, enables the second motor to drive the first maintenance mechanism to move laterally while the second maintenance mechanism moves longitudinally after the first motor is positioned, thereby achieving maintenance of the tail. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the three-dimensional structure of the present invention. Figure 1 .

[0025] Figure 2 This is a schematic diagram of the three-dimensional structure of the adjustment component of the present invention. Figure 1 .

[0026] Figure 3 This is a schematic diagram of the three-dimensional structure of the adjustment component of the present invention. Figure 2 .

[0027] Figure 4 This is a three-dimensional structural diagram of the repair component of the present invention. Figure 1 .

[0028] Figure 5 This is a partial three-dimensional structural diagram of the repair component of the present invention. Figure 1 .

[0029] Figure 6 This is a partial three-dimensional structural diagram of the repair component of the present invention. Figure 2 .

[0030] Figure 7 This is a partial three-dimensional structural diagram of the repair component of the present invention. Figure 3 .

[0031] Figure 8 This is a partial three-dimensional structural diagram of the repair component of the present invention. Figure 4 .

[0032] Figure 9 This is a schematic diagram of the three-dimensional structure of the present invention. Figure 2 .

[0033] In the picture:

[0034] 1. Lifting assembly; 11. Lifting guide rod; 12. Lifting motor; 13. Lifting screw;

[0035] 2. Adjustment components; 21. Z-frame; 22. Guide crossbar; 23. Vertical bar; 24. Horizontal slider; 25. Horizontal screw; 26. Horizontal motor; 27. Lifting T-plate; 28. Vertical plate; 29. ​​Guide plate; 210. Guide mounting rod; 211. Gear; 212. Rack.

[0036] 3. Maintenance components; 31. First maintenance mechanism; 32. Second maintenance mechanism; 33. L-plate; 34. First screw; 35. First motor; 36. First adjusting groove; 37. Second screw; 38. Second adjusting groove; 39. Second motor; 310. Protruding plate; 311. Slide groove; 312. First straight groove; 313. T-block; 314. Second mounting block; 315. First mounting block; 316. Fixed shaft; 317. First sensor; 318. Second sensor; 319. First round shaft; 320. V-bar; 321. Second round shaft; 322. Second straight groove; 323. Slide bar;

[0037] 4. Walking ladder assembly, 41. Steps, 42. Base frame, 43. Wheels. Detailed Implementation

[0038] The following detailed description of a specific embodiment of the present invention is provided in conjunction with the accompanying drawings. However, it should be understood that the scope of protection of the present invention is not limited to the specific embodiment.

[0039] Example 1: The present invention includes a walking ladder assembly 4, which includes a base frame 42, and a step 41 is fixedly connected to the upper side of the base frame 42; the step 41 is fixedly connected to a lifting assembly 1, the lifting assembly 1 is threadedly connected to an adjusting assembly 2, and the adjusting assembly 2 is fixedly connected to two sets of maintenance assemblies 3; the maintenance assembly 3 includes an L-plate 33, the L-plate 33 is provided with a first adjusting groove 36 and a second adjusting groove 38, the L-plate 33 is fixedly connected to a first motor 35, the output shaft of the first motor 35 passes through the L-plate 33 and is fixedly connected to a first screw 34, the first screw 34 is threadedly connected to a protruding plate 310, the protruding plate 310 is nested in the first adjusting groove 36; the L-plate 33 is fixedly connected to a second motor 39, the output shaft of the second motor 39 passes through the L-plate 33 and is fixedly connected to a second screw 37, the second screw 37 is threadedly connected to a T-block 313, the T-block 313 is nested in the second adjusting groove 38; the protruding plate A slide rail 310 is fixedly connected to a slide groove 311. A first sensor 317 is fixedly connected to one side of the slide groove 311, and a second sensor 318 is fixedly connected inside the slide groove 311. A fixed shaft 316 is fixedly connected to the protruding plate 310. A T-block 313 is fixedly connected to a first straight groove 312. A V-rod 320 is rotatably connected to the fixed shaft 316. A first round shaft 319 is fixedly connected to the V-rod 320 and is disposed inside the first straight groove 312. A second round shaft 321 is fixedly connected to the V-rod 320 and is disposed inside the second straight groove 322. A slide bar 323 is nested inside the slide groove 311. The slide bar 323 is fixedly connected to the second straight groove 322. A second mounting block 314 is fixedly connected to the T-block 313. A second maintenance mechanism 32 is fixedly connected to the second mounting block 314. The slide bar 323 is fixedly connected to a first mounting block 315. The first mounting block 315 is fixedly connected to the first maintenance mechanism 31.

[0040] The lifting assembly 1 includes a lifting motor 12 and a lifting guide rod 11. The step 41 is fixedly connected to the lifting motor 12 and the lifting guide rod 11. The output shaft of the lifting motor 12 is fixedly connected to the lifting screw 13.

[0041] The adjustment assembly 2 includes a lifting T-plate 27, a lifting screw 13 threadedly connected to the lifting T-plate 27, lifting guide rods 11 passing through the corresponding lifting T-plates 27, a vertical plate 28 fixedly connected to the lifting T-plate 27, two sets of symmetrical guide plates 29 fixedly connected to the vertical plate 28, a guide crossbar 22 fixedly connected to each guide plate 29, a horizontal motor 26 fixedly connected to the vertical plate 28, a horizontal screw 25 fixedly connected to the output shaft of the horizontal motor 26, a horizontal slider 24 threadedly connected to the horizontal slider 24, a vertical rod 23 fixedly connected to the horizontal slider 24, symmetrical guide crossbars 22 passing through the symmetrical vertical rods 23, Z-frames 21 fixedly connected to the symmetrical vertical rods 23, and L-plates 33 fixedly connected to the symmetrical vertical rods 23.

[0042] The vertical plate 28 is connected to the bearing gear 211, the gear 211 meshes with the symmetrical rack 212, the symmetrical rack 212 is fixedly connected to the guide mounting rod 210, the symmetrical guide mounting rod 210 passes through the corresponding guide plate 29, and the symmetrical guide mounting rod 210 is fixedly connected to the corresponding vertical rod 23.

[0043] The first maintenance mechanism 31 and the second maintenance mechanism 32 include a spraying structure, a spraying mechanism, and a wiping structure. When using the spraying structure, a water pump needs to be connected to spray various maintenance liquids such as lubricating oil, disinfectant cleaning solution, antifreeze, and water. The wiping structure can use a sponge or similar device to apply and wipe away various liquids.

[0044] The horizontal motor 26, the first motor 35, the second motor 39, the first sensor 317, and the second sensor 318 are electrically connected to the controller. A touch screen is installed on one side of the step 41, and the controller is installed inside the touch screen. The motors can be controlled by operating the touch screen.

[0045] A method for using an aircraft maintenance ladder, characterized by comprising the following steps:

[0046] S1: Select the first maintenance mechanism 31 and the second maintenance mechanism 32 according to the maintenance content;

[0047] S2: Push this device to match the position of the vertical tail, and use the first sensor 317 to detect the position of the first maintenance mechanism 31 and the trailing edge of the aircraft vertical tail to match the positions of the two.

[0048] S3: Based on the tail model, the controller intelligently controls the rotation of the horizontal motor 26 to ensure that the distance between the maintenance components 3 on both sides and the tail is appropriate.

[0049] The horizontal motor 26 drives the horizontal screw 25 to rotate, the horizontal screw 25 drives the horizontal slider 24 to move, the horizontal slider 24 drives a vertical rod 23 to move, the vertical rod 23 drives a guide mounting rod 210 and a rack 212 to move, the rack 212 drives a gear 211 to rotate, the gear 211 drives another rack 212, the guide mounting rod 210 and the vertical rod 23 to move, wherein the vertical rod 23 moves along the guide horizontal rod 22, and the vertical rod 23 drives the Z-frame 21 and the maintenance component 3 to move;

[0050] S4: The controller intelligently controls the rotation of the first motor 35 to ensure that the first maintenance mechanism 31 and the second maintenance mechanism 32 are properly positioned relative to the tail. If the first maintenance mechanism 31 and the second maintenance mechanism 32 are made of sponge, they need to be pre-soaked to ensure contact with the tail.

[0051] The first motor 35 drives the first screw 34 to rotate, the first screw 34 drives the convex plate 310 to move along the first adjusting groove 36, the convex plate 310 drives the slide groove 311, the first sensor 317, the second sensor 318, the slide bar 323, the first mounting block 315, the first maintenance mechanism 31, the second straight groove 322, the fixed shaft 316, the V rod 320 and the second round shaft 321 to move, and the V rod 320 drives the first round shaft 319 to move along the first straight groove 312;

[0052] S5: The controller intelligently controls the second motor 39 to reciprocate, enabling the first maintenance mechanism 31 and the second maintenance mechanism 32 to reciprocate and perform maintenance on the aircraft. The second sensor 318 detects the position of the slide bar 323 to determine whether the vertical tail has been fully maintained in the forward and backward direction. At the same time, the controller intelligently controls the lifting motor 12 to rotate, so that the maintenance component 3 performs maintenance on the vertical tail from top to bottom.

[0053] The second motor 39 drives the second screw 37 to reciprocate, the second screw 37 drives the T block 313 to reciprocate along the second adjusting groove 38, the T block 313 drives the first straight groove 312, the second mounting block 314 and the second maintenance mechanism 32 to reciprocate, the first straight groove 312 drives the first round shaft 319 to reciprocate, the first round shaft 319 drives the V rod 320 to reciprocate, the V rod 320 drives the second round shaft 321 to reciprocate along the second straight groove 322, the second round shaft 321 drives the second straight groove 322 to reciprocate, the second straight groove 322 drives the slide bar 323 to reciprocate along the slide groove 311, and the slide bar 323 drives the first mounting block 315 and the first maintenance mechanism 311 to reciprocate.

[0054] Example 2: This example is a further elaboration based on Example 1, wherein the mounting bases of the wheels 43 are fixedly connected to the four lower corners of the base frame 42.

[0055] The wheel 43 has a self-locking function.

[0056] The wheel 43 facilitates the overall movement of this device, making it easy to push it to the vertical tail position of the aircraft for maintenance. The wheel 43 has a self-locking function, which secures the device when the wheel 43 is locked.

[0057] The controller intelligently controls the movement of the horizontal motor 26 to achieve the first positioning of the entire maintenance component 3. The controller intelligently controls the rotation of the first motor 35 to cooperate with the second sensor 318 for a second, more accurate positioning, which drives the second mounting blocks 314 on both sides to extend to the appropriate position. This not only achieves more accurate positioning, but also limits the extreme position of the movement of the first mounting block 315.

[0058] By using the design of connecting round shafts to both ends of the V-rod 20 and setting the round shafts in straight grooves, the second maintenance mechanism 32 moves longitudinally while the first maintenance mechanism 31 moves laterally after the first motor 35 is positioned, thereby achieving the maintenance of the tail.

[0059] The above-disclosed embodiments are merely specific examples of the present invention. However, the present invention is not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. An aircraft maintenance ladder, comprising a walking ladder assembly (4), characterized in that: The walking ladder assembly (4) includes a base frame (42), and a step (41) is fixedly connected to the upper side of the base frame (42). The step (41) is fixedly connected to the lifting assembly (1), the lifting assembly (1) is threadedly connected to the adjusting assembly (2), and the adjusting assembly (2) is fixedly connected to two sets of maintenance assemblies (3). The maintenance component (3) includes an L-plate (33), which is provided with a first adjustment groove (36) and a second adjustment groove (38). The L-plate (33) is fixedly connected to a first motor (35). The output shaft of the first motor (35) passes through the L-plate (33) and is fixedly connected to a first screw (34). The first screw (34) is threadedly connected to a convex plate (310), which is nested in the first adjustment groove (36). The L-plate (33) is fixedly connected to the second motor (39), and the output shaft of the second motor (39) passes through the L-plate (33) and is fixedly connected to the second screw (37). The second screw (37) is threadedly connected to the T-block (313), and the T-block (313) is nested in the second adjustment groove (38). The convex plate (310) is fixedly connected to the slide groove (311), the first sensor (317) is fixedly connected to one side of the slide groove (311), the second sensor (318) is fixedly connected inside the slide groove (311), and the convex plate (310) is fixedly connected to the fixed shaft (316). The T-block (313) is fixedly connected to the first straight groove (312), the fixed shaft (316) is rotatably connected to the V-rod (320), the V-rod (320) is fixedly connected to the first round shaft (319), the first round shaft (319) is disposed in the first straight groove (312), the V-rod (320) is fixedly connected to the second round shaft (321), the second round shaft (321) is disposed in the second straight groove (322); The slide groove (311) is nested with a slide bar (323), the slide bar (323) is fixedly connected to the second straight groove (322), the T block (313) is fixedly connected to the second mounting block (314), the second mounting block (314) is fixedly connected to the second maintenance mechanism (32), the slide bar (323) is fixedly connected to the first mounting block (315), and the first mounting block (315) is fixedly connected to the first maintenance mechanism (31).

2. The aircraft maintenance ladder according to claim 1, characterized in that: The lifting assembly (1) includes a lifting motor (12) and a lifting guide rod (11). The step (41) is fixedly connected to the lifting motor (12) and the lifting guide rod (11). The output shaft of the lifting motor (12) is fixedly connected to the lifting screw (13).

3. The aircraft maintenance ladder according to claim 2, characterized in that: The adjustment assembly (2) includes a lifting T-plate (27), a lifting screw (13) threadedly connected to the lifting T-plate (27), lifting guide rods (11) passing through the corresponding lifting T-plates (27), the lifting T-plate (27) fixedly connected to a vertical plate (28), the vertical plate (28) fixedly connected to two sets of symmetrical guide plates (29), each guide plate (29) fixedly connected to a guide crossbar (22), the vertical plate (28) fixedly connected to a horizontal motor (26), the output shaft of the horizontal motor (26) fixedly connected to a horizontal screw (25), the horizontal screw (25) threadedly connected to a horizontal slider (24), the horizontal slider (24) fixedly connected to a vertical rod (23), the symmetrical guide crossbars (22) passing through the symmetrical vertical rods (23), the symmetrical vertical rods (23) fixedly connected to Z-frames (21), and the symmetrical Z-frames (21) fixedly connected to the corresponding L-plates (33).

4. The aircraft maintenance ladder according to claim 3, characterized in that: The vertical plate (28) is connected to the bearing gear (211), the gear (211) meshes with the symmetrical rack (212), the symmetrical rack (212) is fixedly connected to the guide mounting rod (210), the symmetrical guide mounting rod (210) passes through the corresponding guide plate (29), and the symmetrical guide mounting rod (210) is fixedly connected to the corresponding vertical rod (23).

5. The aircraft maintenance ladder according to claim 4, characterized in that: The first maintenance mechanism (31) and the second maintenance mechanism (32) include a spraying structure, a spraying mechanism and a coating structure.

6. The aircraft maintenance ladder according to claim 5, characterized in that: The mounting bases of the wheels (43) are fixedly connected to the four lower corners of the base frame (42).

7. The aircraft maintenance ladder according to claim 6, characterized in that: The wheel (43) has a self-locking function.

8. The method of using the aircraft maintenance ladder according to claim 7, characterized in that, Includes the following steps: S1: Select the first maintenance agency (31) and the second maintenance agency (32) according to the maintenance content. S2: Push this device to match the position of the vertical tail, and use the first sensor (317) to detect the position of the first maintenance mechanism (31) and the trailing edge of the aircraft vertical tail to match the positions of the two. S3: According to the model of the vertical tail, the controller controls the horizontal motor (26) to rotate so that the distance between the maintenance components (3) on both sides and the vertical tail is appropriate; S4: The controller controls the first motor (35) to rotate so that the first maintenance mechanism (31) and the second maintenance mechanism (32) are in the correct positions with the tail; when the first maintenance mechanism (31) and the second maintenance mechanism (32) are sponges, they need to be soaked in advance so that they come into contact with the tail. S5: The controller controls the second motor (39) to reciprocate, thereby enabling the first maintenance mechanism (31) and the second maintenance mechanism (32) to reciprocate and move to maintain the aircraft. The second sensor (318) detects the position of the slide bar (323) to determine whether the vertical tail has been fully maintained in the forward and backward direction. At the same time, the controller controls the lifting motor (12) to rotate, so that the maintenance component (3) can perform maintenance on the vertical tail from top to bottom.

9. The method of use according to claim 8, characterized in that: The movement of the horizontal motor (26) is controlled by the controller to achieve the first positioning of the entire maintenance component (3). The first motor (35) is rotated by the controller, and the second sensor (318) is used to perform a second more accurate positioning, which drives the second mounting blocks (314) on both sides to extend to the appropriate position. This not only achieves more accurate positioning, but also limits the extreme position of the movement of the first mounting block (315).

10. The method of use according to claim 8, characterized in that: By using the design of connecting the two ends of the V-rod (20) to the round shafts respectively and setting the round shafts in the straight groove, the second motor (39) drives the first maintenance mechanism (31) to move laterally while the second maintenance mechanism (32) moves longitudinally after the first motor (35) is positioned, thus realizing the maintenance of the tail.

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