Triangular track assembly and tractor

Abstract

The invention provides a triangular track assembly and a tractor. With the forward direction of the tractor as the front and the side close to a tractor body as the inner, the device comprises a driving wheel, a pivot, an upper bracket, a limiting shaft, a limiting groove, a lower bracket and a chain link. The driving wheels are arranged on a driving axle of the tractor; the pivot is arranged on the outer side of the driving wheel and integrally rotates with the driving wheel, the upper support is rotatably mounted on the pivot, the limiting groove is mounted on a tractor driving axle, the limiting shaft is inserted into the limiting groove and can slide along the limiting groove, the lower support is arranged below the upper support, and the front end of the lower support is rotatably connected with the upper support. The rear end of the lower support is rotationally connected with the upper support through a chain link. The triangular track assembly is mounted on the upper support as a whole, the upper support is rotationally mounted on the driving wheel, and the triangular track assembly can be directly assembled on the tractor driving axle as a whole and has excellent wheel-track interchangeability.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural machinery, in particular to a triangular crawler assembly and a tractor. Background Art

[0002] Wheeled tractors and crawler tractors have their own advantages and disadvantages in different working conditions. For example, wheeled tractors work well on hard soil, but their off-road ability is weak and their escape performance is poor. They will press deep holes in the cultivated land, causing soil compaction. Crawler tractors have a large ground contact area, low damage to the soil, will not compact the land, and have excellent driving comfort and passing ability. However, the existing triangular crawler device is not only difficult to install and inconvenient to disassemble and assemble, but also has poor interchangeability with tires, making it difficult to give full play to the advantages of the two.

[0003] Therefore, it is necessary to provide a triangular crawler assembly and a tractor to overcome the above-mentioned defectives. Summary of the invention

[0004] The purpose of the present invention is to provide a triangular crawler assembly and a tractor.

[0005] According to one aspect of the present invention, a triangular crawler assembly is provided, with the tractor's forward direction as the front and the side close to the tractor body as the inside, comprising: a driving wheel, the driving wheel is arranged on the tractor drive bridge; a pivot, the pivot is arranged on the outside of the driving wheel and rotates with the driving wheel as a whole; an upper bracket, the upper bracket includes a sleeve portion rotatably mounted on the pivot, a first oblique arm portion arranged on the front side of the sleeve portion, a second oblique arm portion arranged on the rear side of the sleeve portion, a first connecting portion located on the first oblique arm portion, and a second connecting portion located on the second oblique arm portion; a limit Axle, the limit shaft is arranged on the inner side of the first oblique arm part or the second oblique arm part parallel to the pivot; a limit groove, the limit groove is installed on the tractor drive axle, the limit shaft is inserted into the limit groove and can slide along the limit groove; a lower bracket, the lower bracket is arranged below the upper bracket, and the front end of the lower bracket is rotatably connected to the first oblique arm part; a chain link, the chain link includes a first pull rod and a second pull rod hinged to each other, the other end of the first pull rod is rotatably connected to the second oblique arm part, and the other end of the second pull rod is rotatably connected to the rear end of the lower bracket.

[0006] Preferably, the limiting groove is arranged on a limiting bracket, and the limiting bracket is fixed on a tractor drive axle.

[0007] Preferably, the limiting groove is an arc groove with the pivot as the center, and the curvature of the arc groove is not greater than π / 18.

[0008] Preferably, the lower bracket includes two plates and a pin shaft arranged between the two plates, the lower part of the second pull rod is rotatably mounted on the pin shaft, and the middle part of the second pull rod is bent outward and / or inward to form an avoidance portion, so that the upper part of the second pull rod and at least one plate body are located on the same vertical plane, and when the rotation angle of the second pull rod is greater than a threshold value, the avoidance portion will interfere with the plate body.

[0009] Preferably, a first mounting portion is rotatably provided at the front end of the lower bracket, a tensioning actuator is provided between the first mounting portion and the first main body portion, and the tensioning actuator includes an oil cylinder provided between the first mounting portion and the lower bracket and an accumulator provided on the lower bracket and connected to the oil cylinder.

[0010] Preferably, a second mounting portion is fixedly mounted on the rear end of the lower bracket, and a limiting member is arranged between the second oblique arm portion and the second mounting portion, and the limiting member includes a limiting block arranged above the second mounting portion, and a limiting surface arranged below the second oblique arm portion and corresponding to the limiting block.

[0011] Preferably, a third mounting portion is provided in the middle portion of the lower bracket, and a supporting frame capable of swinging along the axial direction of its supporting shaft is provided on the third mounting portion.

[0012] Preferably, a first bearing and a second bearing are arranged between the pivot and the sleeve portion, a first step is arranged on the inner surface of the sleeve portion, a second step is arranged at the connection between the drive wheel and the pivot, the second bearing is axially limited by the outer step surface of the second step and the inner step surface of the first step, the first bearing is axially limited by the outer step surface of the second step and the inner end surface of the limiting nut, and the limiting nut is locked on the outer end surface of the pivot through a threaded connection.

[0013] Preferably, a first groove arranged along the diameter of the pivot is provided on the outer end surface, a third step is provided on the outer end surface of the limit nut, a second groove is provided on the limit nut, the second groove passes through the third step, a flat key is provided between the first groove and the second groove to limit the movement between the limit nut and the pivot, two ends of the flat key are flush with the inner step surface of the second step, the middle position of the flat key is flush with the outer step surface of the second step, an annular groove is provided on the circumference of the second step, an elastic retaining ring is provided in the annular groove, the inner side of the elastic retaining ring abuts against the two ends of the flat key, and the inner ring of the elastic retaining ring abuts against the middle position of the flat key.

[0014] According to another aspect of the present invention, there is provided a tractor comprising the above-mentioned triangular crawler track assembly.

[0015] Compared with the prior art, the triangular crawler track assembly and the tractor provided by the present invention have the following beneficial effects: on the one hand, the present invention installs the triangular crawler track assembly as a whole on the upper bracket, and rotatably installs the upper bracket on the driving wheel, so that the triangular crawler track assembly as a whole can be directly assembled on the tractor drive axle, and has excellent wheel-track interchangeability; on the other hand, the present invention adopts a three-level contoured shock-absorbing structure, which can change with the change of terrain, thereby improving the driving comfort and the passing capacity of the crawler track. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments:

[0017] Figure 1 It is a structural schematic diagram of the triangular crawler assembly in the present invention.

[0018] Figure 2 It is a schematic structural diagram of the triangular track assembly of the present invention (the track, driving wheel, idler wheel and supporting roller are hidden).

[0019] Figure 3 It is a schematic diagram of the structure of the upper bracket and the lower bracket in the present invention.

[0020] Figure 4 It is a cross-sectional schematic diagram of the upper bracket and the lower bracket in the present invention.

[0021] Figure 5 It is a cross-sectional schematic diagram of the second pull rod in the present invention.

[0022] Figure 6 It is a schematic diagram of the structure of the supporting wheel in the present invention.

[0023] Figure 7 It is a cross-sectional schematic diagram of the supporting wheel in the present invention.

[0024] Figure 8 It is a cross-sectional schematic diagram of the pivot and the upper bracket in the present invention.

[0025] Fig. 9 The limiting nut ( Figure 8 A partial enlarged view of the area in the middle.

[0026] Fig.10 It is an exploded schematic diagram of the limiting structure in the present invention.

[0027] Description of reference numerals:

[0028] 1. driving wheel; 11. pivot; 111. second step; 113. first slot;

[0029] 2. upper bracket; 21. first main body; 211. first oblique arm; 212. second oblique arm; 22. sleeve; 221. first step; 222. oil filling hole; 23. first connecting part; 24. second connecting part; 25. tensioning actuator; 26. limiting surface; 27. limiting axis;

[0030] 3. Lower bracket; 31. Second main body; 311. Plate; 312. Pin; 313. Reinforcement rib plate; 314. Limiting area; 32. First mounting part; 33. Second mounting part; 34. Third mounting part; 35. Limiting member; 351. Limiting block; 352. Gasket;

[0031] 4. Chain link; 41. First tie rod; 42. Second tie rod; 421. Upper portion of second tie rod; 422. Avoiding portion; 423. Lower portion of second tie rod;

[0032] 5a, first idler wheel; 5b, second idler wheel;

[0033] 6a, first heavy wheel; 6b, second heavy wheel; 61, supporting shaft; 611, shaft body; 612, spherical structure; 613, swing body; 62, supporting frame;

[0034] 7. Tracks;

[0035] 8. Limit bracket; 81. Bracket body; 82. Limit slot; 83. First mounting rod; 84. Second mounting rod;

[0036] 91. first bearing; 92. second bearing; 93. stop nut; 931. third step; 932. second slot; 934. annular groove; 94. flat key; 95. elastic retaining ring; 96. oil seal assembly;

[0037] 100. triangular crawler track assembly; 200. drive axle; 210. output shaft; 220. output shaft housing. DETAILED DESCRIPTION

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] In order to simplify the drawings, only the parts related to the present invention are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0040] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0041] In this document, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0044] See attached Figures 1 to 10 This embodiment provides a triangular crawler assembly 100, which is used in the field of agricultural machinery such as tractors, to achieve the interchangeability of the triangular crawler assembly 100 and tires. This embodiment is described by taking a tractor as an example, and the forward direction of the tractor is taken as the front, and the side close to the tractor body is taken as the inner side. Unless otherwise specified, the positional relationship between the various components described in this embodiment is the positional relationship between the various components of the triangular crawler assembly 100 in a horizontal and stationary state.

[0045] See attached Figure 2The driving wheel 1 is arranged on the output shaft 210 of the tractor driving bridge 200. The inner side of the driving wheel 1 is connected to the output shaft 210 through a spline. The tractor drives the driving wheel 1 to rotate through the driving bridge 200. A pivot 11 is arranged outside the driving wheel 1. The pivot 11 is coaxially arranged with the output shaft 210 and rotates integrally with the driving wheel 1. The upper bracket 2 is rotatably mounted on the pivot 11 through a bearing.

[0046] See attached Figure 3 The upper bracket 2 includes a first main body 21, a sleeve 22, a first connecting part 23 and a second connecting part 24. The sleeve 22 is loosely sleeved on the pivot 11 through a bearing and can rotate along the pivot 11. When the triangular crawler assembly 100 passes through a depression or a slope, the upper bracket 2 has a certain swing angle to achieve a first-level contour shock absorption function. The first main body 21 is a special-shaped part. The first main body 21 includes a first oblique arm 211 and a second oblique arm 212. The first oblique arm 211 and the second oblique arm 212 extend forward and backward to the outer edge of the driving wheel 1 respectively with the sleeve 22 as the center position, and then extend along the outer edge of the driving wheel 1 to the inner side of the driving wheel 1 to the symmetric plane passing through the inner and outer directions of the driving wheel 1. The first connecting part 23 is arranged on the first oblique arm 211, and the second connecting part 24 is arranged on the second oblique arm 212. The first connecting part 23 and the second connecting part 24 are both arranged forward and located on the symmetric plane of the inner and outer directions of the driving wheel 1.

[0047] It can be understood that there is a single-point connection between the upper bracket 2 and the driving wheel 1. When the triangular track assembly 100 passes through a depression or a slope, the difference in displacement between the front and rear ends of the lower bracket 3 is too large, which will cause the upper bracket 2 and the lower bracket 3 to rotate as a whole along the pivot 11, thereby posing a safety hazard.

[0048] See also Figure 2 A limiting shaft 27 parallel to the pivot 11 is provided on the inner side of the first oblique arm 211 or the second oblique arm 212. Preferably, the limiting shaft 27 is provided on the first oblique arm 211. Correspondingly, a limiting groove 82 is provided on the driving axle 200 of the tractor, and the limiting shaft 27 is inserted into the limiting groove 82 and can slide along the limiting groove 82 to limit the swing angle of the upper bracket 2, so that the rotation angle of the upper bracket 2 and the lower bracket 3 as a whole along the pivot 11 is within a safe range.

[0049] See attached Figure 2The limiting bracket 8 includes a bracket body 81, a limiting groove 82 arranged on the bracket body 81, a first mounting rod 83 connected to the bracket body 81 and fixed on the output shaft housing 220, and a second mounting rod 84 connected to the bracket body 81 and fixed on the side of the tractor drive bridge 200. The limiting groove 82 is an arc groove with the pivot 11 as the center, and the curvature of the arc groove is not greater than π / 18. The limiting shaft 27 is inserted into the limiting groove 82 and can slide along the limiting groove 82 to limit the range of movement of the upper bracket 2, so that the rotation angle of the triangular crawler assembly 100 along the pivot 11 is within a safe range.

[0050] See also Figure 3 , 5 The lower bracket 3 is arranged below the upper bracket 2, and the front end of the lower bracket 3 is rotatably connected to the first oblique arm portion 211. The lower bracket 3 includes a second main body portion 31 arranged below the first main body portion 21, a first mounting portion 32 located at the front end of the second main body portion 31, a second mounting portion 33 located at the rear end of the second main body portion 31, and a third mounting portion 34 located in the middle of the second main body portion 31. The front end of the second main body portion 31 is rotatably connected to the first connecting portion 23, and the other end of the second main body portion 31 is rotatably connected to the second connecting portion 24 through a chain link 4.

[0051] The front end of the lower bracket 3 is rotatably provided with a first mounting portion 32, and a tensioning actuator 25 is provided between the first mounting portion 32 and the first main body portion 21. The tensioning actuator 25 includes a cylinder provided between the first mounting portion 32 and the second main body portion 31 and an accumulator provided on the second main body portion 31 and connected to the cylinder. When the triangular track assembly 100 is loose or encounters certain impacts that cause the track to be tensioned, the cylinder can be extended and retracted in time to adapt to the changes in the track, and the pressure in the cylinder is stabilized by the accumulator to ensure that the entire track 7 is always in a taut state.

[0052] See attached Figure 2 , 5 The chain link 4 includes a first pull rod 41 and a second pull rod 42 which are hinged to each other, the other end of the first pull rod 41 is hinged to the first main body 21, and the other end of the second pull rod 42 is hinged to the rear end of the second main body 31. That is to say, when the lower bracket 3 is displaced, the first pull rod 41 and the second pull rod 42 rotate relatively between the rear end of the first main body 21 and the rear end of the second main body 31, playing a secondary contouring shock absorbing role.

[0053] In order to ensure the smoothness of the tractor's driving, the movement of the chain link 4 needs to be limited to avoid being too large or too small. Figure 2 , 5A limiting member 35 is provided between the second oblique arm portion 212 and the second mounting portion 33. The limiting member 35 includes a limiting block 351 provided above the second mounting portion 33, and a limiting surface 26 provided below the second oblique arm portion 212 and corresponding to the limiting block 351. When the limiting block 351 abuts against the limiting surface 26, the limiting function is realized. The limiting member 35 includes a limiting block 351 detachably mounted on the second main body portion 31, and a gasket 352 adjusted at a height of the limiting block 351 relative to the second main body portion 31. The limiting block 351 is a consumable part made of elastic rubber or other materials, which can not only play a role in shock absorption and buffering, but also adjust the height of the limiting member 35 by setting the number of gaskets 352 to meet different design requirements and compensation for wear of the limiting block 351.

[0054] On the other hand, see Appendix Figure 4 The lower portion 423 of the second pull rod is located on the inner side or the outer side of the second main body portion 31, and the upper portion 421 of the second pull rod is bent outward or inward, so that the upper portion 421 of the second pull rod and the second main body portion 31 are located on the same vertical plane, and the bending transition area between the upper portion 421 of the second pull rod and the lower portion 423 of the second pull rod is the avoidance portion 422. When the second pull rod 42 and the second main body portion 31 rotate relative to each other and the relative rotation angle is small, the avoidance portion 422 does not contact the second main body portion 31. When the rotation angle of the second pull rod 42 and the second main body portion 31 is too large, interference will occur between the avoidance portion 422 and the second main body portion 31, thereby realizing a self-limiting effect and avoiding excessive activity of the chain link 4.

[0055] See attached Figure 5 A reinforcing rib plate 313 is also provided between the two plate bodies 311. Part of the reinforcing rib plate 313 is provided on the movement trajectory of the second pull rod 42. Part of the reinforcing rib plate 313 is defined as a limiting area 314. When the rotation angle of the second pull rod 42 is greater than the threshold value, the second pull rod 42 will rotate counterclockwise with the pin shaft 312 as the rotation point until it collides with the limiting area 314 of the reinforcing rib plate 313. At this time, the triangular crawler assembly 100 reaches the maximum activity, thereby ensuring the structural stability and driving stability of the tractor.

[0056] See attached Figure 1 The idler wheel includes a first idler wheel 5a mounted on the first mounting portion 32 and a second idler wheel 5b mounted on the second mounting portion 33. The supporting rollers include a first supporting roller 6a and a second supporting roller 6b provided on the third mounting portion 34. The crawler track 7 is wound across the driving wheel 1, the first idler wheel 5a, the first supporting roller 6a, the second supporting roller 6b and the second idler wheel 5b, so that the rotation of the driving wheel 1 causes the crawler track 7 to move.

[0057] See attached Figure 6The supporting wheels include a supporting frame 62 mounted on the third mounting portion 34 and capable of swinging along its supporting shaft 61. The first supporting wheel 6a and the second supporting wheel 6b are respectively mounted at the front and rear ends of the supporting frame 62, so that the first supporting wheel 6a and the second supporting wheel 6b can change along a direction perpendicular to the axial direction of the supporting shaft 61 (i.e., the forward direction) as the terrain changes, thereby achieving a contour-based shock-absorbing effect.

[0058] See attached Figure 7 The supporting shaft 61 includes a shaft body 611, a spherical structure 612 is arranged at the center of the shaft body 611, and a layer of elastic material with a predetermined thickness, such as rubber material, is wrapped around the spherical structure 612. The elastic material forms a swing body 613, and the supporting frame 62 is sleeved on the swing body 613. When the crawler 7 is displaced along the axial direction (i.e., the inner and outer directions) of the first and second rollers 6a, 6b of the supporting shaft 61, the swing body 613 will be deformed, so that the first and second rollers 6a, 6b change along the inner and outer directions with the change of the terrain, thereby realizing the three-level contour-matching shock-absorbing function. At the same time, the plasticity of the swing body 613 can also reduce the impact of ground changes on the tractor.

[0059] Among them, the entire triangular track assembly 100 is directly installed on the end drive axle 200 of the tractor as a whole, that is, the stress of the triangular track assembly 100 is all concentrated between the pivot 11 and the sleeve part 22. Therefore, how to ensure the connection stability between the pivot 11 and the upper bracket 2 is the basis and difficulty of realizing the design of the triangular track assembly 100.

[0060] In this embodiment, in order to ensure the structural strength of the pivot 11, the traditional bolt fixing method is abandoned and an anti-slip structure for the shaft is designed. Figure 8 A first bearing 91 and a second bearing 92 are provided between the pivot 11 and the sleeve portion 22 to realize the rotational connection between the pivot 11 and the upper bracket 2. A first step 221 is provided on the inner surface of the sleeve portion 22, and a second step 111 is provided at the connection between the driving wheel 1 and the pivot 11. The second bearing 92 is axially limited by the outer step surface of the second step 111 and the inner step surface of the first step 221. The first bearing 91 is axially limited by the outer step surface of the second step 111 and the inner end surface of the limiting nut 93. The limiting nut 93 is locked on the pivot 11 through a threaded connection.

[0061] See attached Fig. 9, an oil seal assembly 96 is provided at the connection between the driving wheel 1, the pivot 11 and the sleeve portion 22, and the oil seal assembly 96 includes a first sealing ring and a second sealing ring, a first sealing ring provided on the first sealing ring and connected to the driving wheel 1, and a second sealing ring provided on the second sealing ring and connected to the inner wall of the sleeve portion 22. The first bearing 91 and the second bearing 92 are spaced at a predetermined distance, and a lubricating oil cavity is formed between the pivot 11 and the sleeve portion 22, and a corresponding oil injection hole 222 is provided on the sleeve portion 22 to achieve lubrication of the first bearing 91 and the second bearing 92.

[0062] See attached Fig. 9 , 10 A first slot 113 is provided on the outer end surface of the pivot 11 along its diameter, a third step 931 is provided on the limiting nut 93, a second slot 932 is provided on the limiting nut 93, the second slot 932 runs through the third step 931, a flat key 94 is clamped between the first slot 113 and the second slot 932, and the movement between the limiting nut 93 and the pivot 11 is limited by the flat key 94, the two ends of the flat key 94 are flush with the inner step surface of the second step 111, the middle position of the flat key 94 is flush with the outer step surface of the second step 111, an annular groove 934 is provided on the circumference of the second step 111, and an elastic retaining ring 95 is arranged in the annular groove 934, the inner side of the elastic retaining ring 95 abuts against the two ends of the flat key 94, and the inner ring of the elastic retaining ring 95 abuts against the middle position of the flat key 94.

[0063] The limiting nut 93 is installed on the pivot 11, and the limiting nut 93 is against the outer side of the first bearing 91, and then the flat key 94 is clamped between the first clamping groove 113 and the second clamping groove 932, and finally the elastic retaining ring 95 is clamped in the annular groove 934 to fix the flat key 94, avoid relative rotation between the limiting nut 93 and the pivot 11, and further avoid relative movement between the upper bracket 2 and the pivot 11.

[0064] It will be apparent to those skilled in the art that various modifications and variations may be made to the above exemplary embodiments of the present invention without departing from the spirit and scope of the present invention. Therefore, it is intended that the present invention covers modifications and variations of the present invention that fall within the scope of the appended claims and their equivalent technical solutions.

Claims

1. A triangular crawler assembly for a tractor, characterized in that: The front is the direction of the tractor's forward movement, and the side close to the tractor body is the inside, including: A driving wheel, wherein the driving wheel is arranged on the driving axle of the tractor; A pivot shaft, the pivot shaft being arranged outside the driving wheel and rotating integrally with the driving wheel; An upper bracket, the upper bracket comprising a sleeve portion rotatably mounted on the pivot, a first oblique arm portion arranged at the front side of the sleeve portion, a second oblique arm portion arranged at the rear side of the sleeve portion, a first connecting portion located at the first oblique arm portion, and a second connecting portion located on the second oblique arm portion; A limiting shaft, the limiting shaft is parallel to the pivot and is arranged on the inner side of the first oblique arm part or the second oblique arm part; A limiting groove, wherein the limiting groove is installed on the tractor drive axle, and the limiting shaft is inserted into the limiting groove and can slide along the limiting groove; A lower bracket, wherein the lower bracket is arranged below the upper bracket, and a front end of the lower bracket is rotatably connected to the first oblique arm portion; The chain link comprises a first pull rod and a second pull rod which are hinged to each other, the other end of the first pull rod is rotatably connected to the second oblique arm portion, and the other end of the second pull rod is rotatably connected to the rear end of the lower bracket.

2. The triangular crawler track assembly for a tractor according to claim 1, characterized in that: The limiting groove is arranged on the limiting bracket, and the limiting bracket is fixed on the driving axle of the tractor.

3. The triangular crawler track assembly for a tractor according to claim 2, characterized in that: The limiting groove is an arc groove with the pivot as the center, and the curvature of the arc groove is not greater than π / 18.

4. The triangular crawler track assembly for a tractor according to claim 1, characterized in that: The lower bracket includes two plates and a pin shaft arranged between the two plates. The lower part of the second pull rod is rotatably mounted on the pin shaft. The middle part of the second pull rod is bent outward and / or inward to form an avoidance portion, so that the upper part of the second pull rod and at least one plate body are located on the same vertical plane. When the rotation angle of the second pull rod is greater than a threshold value, the avoidance portion will interfere with the plate body.

5. The triangular crawler track assembly for a tractor according to claim 2, characterized in that: A reinforcing rib plate is also provided between the two plates, and a partial area of ​​the reinforcing rib plate is provided on the movement track of the second pull rod. When the rotation angle of the second pull rod is greater than a threshold value, the second pull rod will interfere with a partial area of ​​the reinforcing rib plate.

6. The triangular crawler track assembly for a tractor according to claim 1, characterized in that: A first mounting portion is rotatably provided at the front end of the lower bracket, a tensioning actuator is provided between the first mounting portion and the first main body portion, and the tensioning actuator comprises an oil cylinder provided between the first mounting portion and the lower bracket and an accumulator provided on the lower bracket and connected to the oil cylinder.

7. The triangular crawler track assembly for a tractor according to claim 1, characterized in that: A second mounting portion is fixedly mounted on the rear end of the lower bracket, and a limiting member is arranged between the second oblique arm portion and the second mounting portion. The limiting member includes a limiting block arranged above the second mounting portion and a limiting surface arranged below the second oblique arm portion and corresponding to the limiting block.

8. The triangular crawler track assembly for a tractor according to claim 1, characterized in that: A first bearing and a second bearing are arranged between the pivot and the sleeve portion, a first step is arranged on the inner surface of the sleeve portion, a second step is arranged at the connection between the drive wheel and the pivot, the second bearing is axially limited by the outer step surface of the second step and the inner step surface of the first step, the first bearing is axially limited by the outer step surface of the second step and the inner end surface of the limiting nut, and the limiting nut is locked on the outer end surface of the pivot through a threaded connection.

9. The triangular crawler track assembly for a tractor according to claim 8, characterized in that: A first clamping groove arranged along the diameter of the pivot is provided on the outer end surface, a third step is provided on the outer end surface of the limit nut, a second clamping groove is provided on the limit nut, the second clamping groove passes through the third step, a flat key is provided between the first clamping groove and the second clamping groove to limit the movement between the limit nut and the pivot, two ends of the flat key are flush with the inner step surface of the second step, the middle position of the flat key is flush with the outer step surface of the second step, an annular groove is provided on the circumference of the second step, an elastic retaining ring is provided in the annular groove, the inner side of the elastic retaining ring abuts against the two ends of the flat key, and the inner ring of the elastic retaining ring abuts against the middle position of the flat key.

10. A tractor, characterized in that: It comprises the triangular crawler assembly as described in any one of claims 1 to 9.

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