A high-load unmanned aerial vehicle

Abstract

The utility model provides a kind of high load's unmanned plane, belong to unmanned plane equipment technical field, including the landing gear of load unmanned plane bottom, the load platform being set in landing gear middle part, the left and right sides of landing gear are respectively provided with one pivot, the front and rear ends of each pivot are respectively provided with one limit box, one rotating component is respectively provided in each limit box, the surface of each rotating component is respectively provided with one locking structure, one connecting piece is provided in the side of each limit box close to landing gear, connecting piece is fixedly connected with landing gear, the utility model is adjusted by rotating component and makes damping seat and pivot overturn, limit after pivot overturn by locking structure, to reach the purpose of fixed pivot after pivot overturn adjustment, so that damping seat can be folded and stored on landing gear, the transportation of unmanned plane is convenient, prevent the damage of damping component in the bottom of load unmanned plane during transportation, to improve the service life of component.

Description

Technical Field

[0001] This utility model relates to the field of unmanned aerial vehicle (UAV) equipment technology, specifically to a high-payload UAV. Background Technology

[0002] A high-payload drone is a drone system capable of carrying a large payload. It typically has a powerful power system and stable flight control capabilities, and can carry cargo, equipment, or sensors for flight missions.

[0003] In related technologies, after a high-payload drone carries cargo and needs to land, the drone will impact the ground due to gravity. This impact will cause relative movement between the drone and the ground, resulting in vibration. Imbalance or loss of control during landing, as well as airflow during descent, will all cause the high-payload drone to vibrate upon landing. Excessive vibration can damage the internal components of the drone. Therefore, some high-payload drones are equipped with shock-absorbing landing gear at the bottom.

[0004] However, most of the shock-absorbing components inside this landing gear are fixed to the landing gear, which is inconvenient to transport and carry. When not taking off or landing, the shock-absorbing parts are often in contact with the ground, which will also reduce the service life of the shock-absorbing components. To solve the above problems, a high-payload UAV is proposed. Utility Model Content

[0005] In view of this, the present invention provides a high-load-bearing drone. The present invention uses a locking structure to limit the rotation of the shaft after it is flipped, thereby achieving the purpose of fixing the shaft after the rotation adjustment. This allows the shock absorber to be folded and stored on the landing gear, which facilitates the transportation of the drone and prevents damage to the shock absorber components at the bottom of the heavy-duty drone during transportation, thereby improving the service life of the components.

[0006] To solve the above-mentioned technical problems, this utility model provides a high-payload drone, including a landing gear at the bottom of the drone, a load-bearing platform in the middle of the landing gear, a rotating shaft on each of the left and right sides of the landing gear, a limiting box at the front and rear ends of each rotating shaft, a rotating component inside each limiting box, a locking structure on the surface of each rotating component, and a connector on the side of each limiting box near the landing gear, the connector being fixedly connected to the landing gear.

[0007] Each limiting box has a sealing ring embedded in its wall. The sealing ring is rotatably adapted to the surface of the rotating shaft. The sealing ring is used to help support the rotating shaft and fix it in the middle of the two limiting boxes, thereby reducing the axial stress of fixing the rotating shaft between the triangular bases. The rotating shaft is located between the two sealing rings on the same side.

[0008] Each rotating component includes a triangular base fixed inside a limiting box. The triangular base is used to fix the rotating shaft, allowing the rotating shaft to be rotated and adjusted on the triangular base. Each triangular base is rotatably connected to the end of its corresponding rotating shaft.

[0009] A linkage shaft is installed through the triangular base. The linkage shaft is used to connect the rotating shaft to the pressure tongue. Each surface of the linkage shaft is provided with a pressure tongue, which is used to engage the receiving tongue, thereby limiting the rotation of the rotating shaft. Then, when the pressure tongue contacts the upper receiving tongue, the shock absorber retracts. When the pressure tongue contacts the lower receiving tongue, the shock absorber contacts the ground, assisting the UAV in taking off and landing.

[0010] Each locking mechanism includes a connecting plate fixed inside the limiting box. The connecting plate is used to fix two pairs of slide rails, thereby supporting the connecting block, slider, linkage plate, and receiving tongue. The connecting plate is located at the bottom of the linkage shaft. A pair of slide rails are respectively provided at the front and rear ends of the connecting plate. The slide rails are used for slider movement, so that the linkage plate and receiving tongue can move with the downward pressure of the spring rod. A linkage plate is slidably arranged between each pair of slide rails. The linkage plate is used to connect the slider, spring rod, and receiving tongue. A receiving tongue is provided at the bottom of each linkage plate. The receiving tongue is used to limit and fix the pressure tongue, preventing the pressure tongue from falling off after it is fixed. The receiving tongue and the pressure tongue are properly engaged.

[0011] Each locking structure also includes a connecting block on the top of its linkage plate. The connecting block is used to connect the linkage plate and the spring rod. The spring rod is located on the top of the connecting block and is used to press the linkage plate, thereby causing the slider to move the receiving tongue, which facilitates the separation or connection of the receiving tongue and the pressure tongue. When the pressure tongue is separated from the receiving tongue, the rotating shaft and the shock absorber can be folded. When the pressure tongue is connected to the receiving tongue, the rotating shaft and the shock absorber are positioned. The spring rod passes through the wall of the limiting box and is respectively provided with a positioning block. The positioning block is used to fix the top of the spring rod and connect the bottom of the spring rod to the top of the limiting box. The pressure head of each spring rod passes through the positioning block.

[0012] Each slide rail has a slider that slides inside. The slider is used to move the linkage plate and the receiving tongue. The end of the slider is fixedly connected to the connecting plate on the same side. A return spring is provided at the bottom of the slider and is connected to the bottom of the slide rail. The return spring is used to facilitate the slider to return to its original position.

[0013] Each rotating shaft has a connecting sleeve fixedly installed on its surface. The connecting sleeve is used to connect the rotating shaft to the shock absorber seat. A shock absorber seat is installed on one side of each connecting sleeve. The shock absorber seat is used to dampen the landing gear of the UAV. The shock absorber seat is trapezoidal and has a cavity inside. A rubber shock absorber block is installed in the cavity. The rubber shock absorber block is used to reduce the vibration force generated when the landing gear contacts the ground during take-off and landing operations. A wear-resistant plate is installed at the bottom of the rubber shock absorber block to contact the ground. The wear-resistant plate is used to prevent the rubber shock absorber block from directly contacting the ground, thereby improving the service life of the rubber shock absorber block.

[0014] In summary, compared with the prior art, this application includes at least one of the following beneficial technical effects: 1. By pressing the spring lever slider, the mounting tongue moves, and the rotating shaft flips simultaneously. This allows the pressure tongue on the linkage shaft to flip. When the pressure tongue contacts the upper mounting tongue, the shock absorber can fold and retract to the upper part of the rotating shaft, making it easy to store and transport. This prevents damage to the shock-absorbing components at the bottom of the drone during transport, thus improving the service life of the components. When the pressure tongue contacts the lower mounting tongue, the shock absorber can flip to the lower part of the rotating shaft. At this time, the shock absorber contacts the ground, assisting the drone in takeoff and reducing the vibration generated during landing.

[0015] 2. The linkage plate and the spring pressure rod are connected by the connecting block. The spring pressure rod is used to press the linkage plate, thereby causing the slider to move the receiving tongue, which facilitates the separation or connection of the pressure tongue and the receiving tongue. When the pressure tongue is separated from the receiving tongue, the rotating shaft and the shock absorber can be folded. When the pressure tongue is connected to the receiving tongue, the rotating shaft and the shock absorber are positioned. The positioning block is used to fix the top of the spring pressure rod, so that the bottom of the spring pressure rod is connected to the top of the limit box.

[0016] 3. The rotating shaft is connected to the shock absorber seat through the connecting sleeve. The shock absorber seat is used to dampen the landing gear of the UAV. The rubber shock absorber block is used to reduce the vibration force generated when the landing gear contacts the ground during take-off and landing operations. The wear-resistant plate is used to prevent the rubber shock absorber block from directly contacting the ground, thereby improving the service life of the rubber shock absorber block. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the main structure of this utility model; Figure 2 This is a side sectional view of the present invention; Figure 3 This utility model Figure 2 A magnified view of part A; Figure 4 This utility model Figure 2 A magnified view of part B; Figure 5 This is a front sectional view of the present invention; Figure 6This utility model Figure 5 A magnified view of part C; Figure 7 This utility model Figure 5 A magnified view of part D; Figure 8 This is a side sectional view of the present invention; Figure 9 This utility model Figure 8 A magnified view of part E.

[0018] Explanation of reference numerals in the attached drawings: 100, unmanned aerial vehicle (UAV) with heavy load; 101, landing gear; 102, load-bearing platform; 103, rotating shaft; 104, limit box; 105, sealing ring; 200, rotating component; 201, triangular base; 202, linkage shaft; 203, pressure tongue; 300, locking structure; 301, connecting plate; 302, slide rail; 303, slider; 304, linkage plate; 305, receiving tongue; 306, connecting block; 307, spring pressure rod; 308, positioning block; 309, return spring; 400, connecting piece; 401, connecting sleeve; 402, shock absorber seat; 403, rubber shock absorber block; 404, wear-resistant plate. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the following will be described in conjunction with the accompanying drawings of the embodiments of this utility model. Figure 1-9 The technical solutions of the embodiments of this utility model are clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the described embodiments of this utility model are within the protection scope of this utility model.

[0020] like Figure 1-9As shown: This embodiment provides a high-payload unmanned aerial vehicle (UAV), including a landing gear 101 at the bottom of the UAV 100, a load-bearing platform 102 in the middle of the landing gear 101, a rotating shaft 103 on each of the left and right sides of the landing gear 101, a limiting box 104 at each of the front and rear ends of each rotating shaft 103, a maintenance plate detachably provided on one side of the limiting box 104, a rotating component 200 inside each limiting box 104, the rotating component 200 facilitating the rotation and adjustment of the rotating shaft 103, and a locking structure 30 on the surface of each rotating component 200. 0. The locking structure 300 is used to limit the rotation of the shaft 103 after it is flipped, thereby achieving the purpose of fixing the shaft 103 after it is flipped and adjusted. Each limiting box 104 is provided with a connector 400 on the side near the landing gear 101. The connector 400 is used to connect the limiting box 104 to the landing gear 101. The connector 400 includes a support rod connected to the landing gear 101. A support seat is provided at the bottom of the support rod. The limiting box 104 can be welded to the support seat or fixed to the side of the support seat away from the center of the UAV by bolts. The connector 400 is fixedly connected to the landing gear 101.

[0021] In use, pressing the spring lever 307 causes the linkage plate 304 to move the mounting tongue 305, simultaneously causing the rotating shaft 103 to flip the shock absorber 402. This allows the pressure tongue 203 on the linkage shaft 202 to flip, engaging with the mounting tongue 305 to limit the rotation shaft 103. When the pressure tongue 203 contacts the upper mounting tongue 305, the shock absorber 402 can fold and retract to the upper part of the rotating shaft 103. When the pressure tongue 203 contacts the lower mounting tongue 305, the shock absorber 402 can flip to the lower part of the rotating shaft 103, at which point the shock absorber 402 contacts the ground, assisting the drone in take-off and landing. Similarly, the folding and storage of the shock absorber 402 facilitates transportation, preventing damage to the shock-absorbing components at the bottom of the heavy-duty drone 100 during transport, thereby improving the service life of the components.

[0022] This embodiment provides a high-payload drone. like Figure 1 , 2 As shown in Figure 3: Each limiting box 104 has a sealing ring 105 embedded in its wall. The sealing ring 105 is rotatably adapted to the surface of the rotating shaft 103. The sealing ring 105 is used to assist in supporting the rotating shaft 103 to be fixed in the middle of the two limiting boxes 104, thereby reducing the axial stress of fixing the rotating shaft 103 between the triangular bases 201. The rotating shaft 103 is located between the two sealing rings 105 on the same side.

[0023] Its effect is that the sealing ring 105 is used to assist in supporting the rotating shaft 103 to be fixed in the middle of the two limit boxes 104, thereby reducing the axial stress of the rotating shaft 103 fixed between the triangular bases 201.

[0024] like Figure 2 , 3 As shown in Figures 6, 7, and 9: Each rotating component 200 includes a triangular base 201 fixed inside the limiting box 104. The triangular base 201 is fixedly connected to the inner wall of the limiting box 104. A bearing is provided inside the triangular base 201 and is rotatably connected to the rotating shaft 103. The triangular base 201 is used to fix the rotating shaft 103, so that the rotating shaft 103 can be rotated and adjusted on the triangular base 201. Each triangular base 201 is rotatably connected to the end of its corresponding rotating shaft 103. A linkage shaft 202 is provided through the triangular base 201. The linkage shaft 202 is welded to the rotating shaft 103. The linkage shaft 202 is used to connect the rotating shaft 103 to the pressure tongue 203. Each surface of the linkage shaft 202 is provided with a pressure tongue 203. The pressure tongue 203 is welded and fixed to the surface of the linkage shaft 202. The pressure tongue 203 is used to engage the receiving tongue 305, thereby limiting the rotating shaft 103. Then, when the pressure tongue 203 contacts the upper receiving tongue 305, the shock absorber 402 retracts. When the pressure tongue 203 contacts the lower receiving tongue 305, the shock absorber 402 contacts the ground, assisting the UAV in taking off and landing.

[0025] Its effects are as follows: the triangular base 201 is used to fix the rotating shaft 103, so that the rotating shaft 103 can be rotated and adjusted on the triangular base 201; the linkage shaft 202 is used to connect the rotating shaft 103 with the pressure tongue 203; the tongue is used to engage the receiving tongue 305, thereby limiting the rotating shaft 103; and when the pressure tongue 203 contacts the upper receiving tongue 305, the shock absorber 402 retracts; when the pressure tongue 203 contacts the lower receiving tongue 305, the shock absorber 402 contacts the ground, assisting the UAV in taking off and landing.

[0026] like Figure 3 , 6As shown in Figures 7 and 9: Each locking structure 300 includes a connecting plate 301 fixed inside the limiting box 104. The connecting plate 301 is fixed inside the limiting box 104 by bolts. Positioning bolts can be added to the connecting plate 301 to reinforce the connecting member 400. The connecting plate 301 is used to fix two pairs of slide rails 302. The slide rails 302 and the connecting plate 301 can be welded together, thereby supporting the connecting block 306, the slider 303, the linkage plate 304, and the receiving tongue 305. The connecting plate 301 is located at the bottom of the linkage shaft 202. A pair of slide rails 302 are respectively provided at the front and rear ends of the connecting plate 301. The slide rails 302 are used for... The slider 303 moves, so that the linkage plate 304 and the receiving tongue 305 can move with the downward pressure of the spring rod 307. A linkage plate 304 is slidably arranged between each pair of slide rails 302. The linkage plate 304 is slidably adapted to the side of the slide rail 302. The linkage plate 304 is used to connect the slider 303, the spring rod 307 and the receiving tongue 305. A receiving tongue 305 is provided at the bottom of each linkage plate 304. The receiving tongue 305 can be welded to the linkage plate 304. The receiving tongue 305 is used to limit and fix the pressure tongue 203 to prevent the pressure tongue 203 from falling after it is fixed. The receiving tongue 305 and the pressure tongue 203 are locked together.

[0027] Its effect is as follows: the connecting plate 301 is used to fix two pairs of slide rails 302. The slide rails 302 and the connecting plate 301 can be welded together, so that the connecting block 306, the slider 303, the linkage plate 304 and the receiving tongue 305 can be supported. The slide rails 302 are used for the slider 303 to move, so that the linkage plate 304 and the receiving tongue 305 can move with the downward pressure of the spring pressure rod 307. The receiving tongue 305 is used to limit and fix the pressure tongue 203 to prevent the pressure tongue 203 from falling off after it is fixed.

[0028] As shown in the figure: Each locking structure 300 also includes a connecting block 306 respectively provided on the top of its linkage plate 304. The connecting block 306 and the linkage plate 304 can be heat-fused together. The connecting block 306 is used to connect the linkage plate 304 and the spring pressure rod 307. The top of the connecting block 306 is provided with a spring pressure rod 307. The spring pressure rod 307 is provided with a movable rod and a spring. The spring pressure rod 307 is used to press the linkage plate 304, thereby causing the slider 303 to drive the receiving tongue 305 to move, thereby facilitating the separation or connection of the pressure tongue 203 and the receiving tongue 305. When the pressure tongue 203 and the receiving tongue 305 are separated... The rotating shaft 103 and the shock absorber 402 are foldable. When the pressure tongue 203 is connected to the receiving tongue 305, the rotating shaft 103 and the shock absorber 402 are positioned. The spring pressure rod 307 passes through the box wall of the limiting box 104 and is respectively provided with a positioning block 308. The positioning block 308 is fixed on the outer wall of the limiting box 104. The middle of the positioning block 308 is provided with an opening that matches the spring pressure rod 307. The positioning block 308 is used to fix the top of the spring pressure rod 307 so that the bottom of the spring pressure rod 307 is connected to the top of the limiting box 104. The pressure head of each spring pressure rod 307 passes through the positioning block 308.

[0029] Its effect is as follows: the linkage plate 304 and the spring pressure rod 307 are connected by the connecting block 306. The spring pressure rod 307 is used to press the linkage plate 304, thereby causing the slider 303 to drive the hanging tongue 305 to move, thus facilitating the separation or connection of the pressure tongue 203 and the hanging tongue 305. When the pressure tongue 203 is separated from the hanging tongue 305, the rotating shaft 103 and the shock absorber 402 can be folded. When the pressure tongue 203 is connected to the hanging tongue 305, the rotating shaft 103 and the shock absorber 402 are positioned. The positioning block 308 is used to fix the top of the spring pressure rod 307, so that the bottom of the spring pressure rod 307 is connected to the top of the limit box 104.

[0030] like Figure 5 , 6 As shown in Figures 7 and 9: Each slide rail 302 has a slider 303 slidably installed inside it. The slider 303 is slidably adapted to the slide groove inside the slide rail 302. The slider 303 is used to move the linkage plate 304 and the receiving tongue 305. The slider 303 is fixedly connected to the end of the connecting plate 301 on the same side. A return spring 309 is provided at the bottom of the slider 303. The return spring 309 is used to pull the receiving tongue 305 and the pressure tongue 203 to have a range of motion in the slide rail 302. The return spring 309 is fixedly connected to the bottom of the slide rail 302. The other end of the return spring 309 is fixedly connected to the slider 303. The return spring 309 is used to facilitate the return of the slider 303.

[0031] like Figure 2 , 3As shown in Figure 4: A connecting sleeve 401 is fixedly installed on the surface of each rotating shaft 103. The connecting sleeve 401 is welded to the surface of the rotating shaft 103. The connecting sleeve 401 is used to connect the rotating shaft 103 to the shock absorber 402. A shock absorber 402 is provided on one side of the connecting sleeve 401. The shock absorber 402 is welded to the connecting sleeve 401. The shock absorber 402 is used to dampen the landing gear 101 of the UAV. The shock absorber 402 is trapezoidal and has a cavity inside. A rubber shock absorber block is installed in the cavity. 403. The rubber damping block 403 and the damping seat 402 can be fixed by bolts. The rubber damping block 403 is used to reduce the vibration force generated when the landing gear 101 contacts the ground during take-off and landing operations. The bottom of the rubber damping block 403 is provided with a wear-resistant plate 404 that contacts the ground. The wear-resistant plate 404 can be made of aluminum alloy. The wear-resistant plate 404 and the rubber damping block 403 are fixed by bolts. The wear-resistant plate 404 is used to prevent the rubber damping block 403 from directly contacting the ground, thereby improving the service life of the rubber damping block 403.

[0032] Its effect is as follows: the connecting sleeve 401 connects the rotating shaft 103 to the shock absorber 402. The shock absorber 402 is used to dampen the landing gear 101 of the UAV. The rubber shock absorber 403 is used to reduce the vibration force generated when the landing gear 101 contacts the ground during take-off and landing operations. The wear-resistant plate 404 is used to prevent the rubber shock absorber 403 from directly contacting the ground, thereby improving the service life of the rubber shock absorber 403.

[0033] Working principle: Before the drone is placed on the ground for flight, pressing the spring lever 307 causes the linkage plate 304 to move the mounting tongue 305. By manually flipping the shock absorber seat 402, the rotating shaft 103 can be adjusted between the two triangular bases 201, which in turn allows the pressure tongue 203 on the linkage shaft 202 to flip. The pressure tongue 203 engages with the mounting tongue 305, thus limiting the rotation shaft 103. When the pressure tongue 203 contacts the upper mounting tongue 305, the shock absorber seat 402 can be folded and retracted to the upper part of the rotating shaft 103. When the pressure tongue 203 contacts the lower mounting tongue 305, the shock absorber seat 402 can be flipped to the lower part of the rotating shaft 103. At this time, the shock absorber seat 402 is in contact with the ground, assisting the drone in take-off and landing. Similarly, the folding and storage of the shock absorber seat 402 facilitates transportation and prevents damage to the shock-absorbing components at the bottom of the drone 100 during transportation, thereby improving the service life of the components.

[0034] Furthermore, it should be noted that, in the description of this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0035] The above description is the preferred embodiment of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications should also be considered within the protection scope of this utility model.

Claims

1. A high-payload unmanned aerial vehicle (UAV), comprising a landing gear (101) at the bottom of a heavy-duty UAV (100), and a load-bearing platform (102) disposed in the middle of the landing gear (101), characterized in that: The landing gear (101) has a rotating shaft (103) on its left and right sides respectively. Each rotating shaft (103) has a limiting box (104) at its front and rear ends respectively. Each limiting box (104) has a rotating component (200) inside it. Each rotating component (200) has a locking structure (300) on its surface. Each limiting box (104) has a connector (400) on the side near the landing gear (101) and the connector (400) is fixedly connected to the landing gear (101).

2. The high-payload drone as described in claim 1, characterized in that: Each of the limiting boxes (104) has a sealing ring (105) embedded in its wall, and the rotating shaft (103) is located between the two sealing rings (105) on the same side.

3. A high-payload unmanned aerial vehicle as described in claim 2, characterized in that: Each of the rotating components (200) includes a triangular base (201) fixed inside the limiting box (104), and each triangular base (201) is rotatably connected to the end of its corresponding rotating shaft (103).

4. A high-payload unmanned aerial vehicle as described in claim 3, characterized in that: The rotating shaft (103) passes through the triangular base (201) and is provided with a linkage shaft (202). Each surface of the linkage shaft (202) is provided with a pressure tongue (203).

5. A high-payload unmanned aerial vehicle as described in claim 4, characterized in that: Each of the locking structures (300) includes a connecting plate (301) fixed inside the limiting box (104). The connecting plate (301) is located at the bottom of the linkage shaft (202). A pair of slide rails (302) are respectively provided at the front and rear ends of the connecting plate (301). A linkage plate (304) is slidably arranged between each pair of slide rails (302). A receiving tongue (305) is provided at the bottom of each linkage plate (304). The receiving tongue (305) is engaged and matched with the pressing tongue (203).

6. A high-payload unmanned aerial vehicle as described in claim 5, characterized in that: Each of the locking structures (300) further includes a connecting block (306) respectively provided on the top of the linkage plate (304), and a spring pressure rod (307) is provided on the top of the connecting block (306). The spring pressure rod (307) passes through the box wall of the limiting box (104) and is respectively provided with a positioning block (308). The pressure head of each spring pressure rod (307) passes through the positioning block (308).

7. A high-payload unmanned aerial vehicle as described in claim 6, characterized in that: Each slide rail (302) has a slider (303) slidably disposed therein. The slider (303) is fixedly connected to the end of the connecting plate (301) on the same side. A return spring (309) is provided at the bottom of the slider (303), and the return spring (309) is connected to the bottom of the slide rail (302).

8. A high-payload unmanned aerial vehicle as described in claim 7, characterized in that: Each of the rotating shafts (103) has a connecting sleeve (401) fixedly installed on its surface. A shock absorber (402) is provided on one side of each connecting sleeve (401). The shock absorber (402) is trapezoidal and has a cavity inside. A rubber shock absorber (403) is provided inside the cavity. A wear-resistant plate (404) is provided at the bottom of the rubber shock absorber (403) to contact the ground.

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