Agricultural machine walking driving gearbox

Abstract

The present application relates to the field of farm machinery gearbox, specifically to a farm machinery walking driving gearbox, comprising a gearbox body, a push rod connected to a shift paddle in the gearbox body, a round hole is formed on the gearbox body, the push rod extends to outside of the gearbox body through the round hole, a locking block is fixedly installed on one side of the gearbox body, a through hole coaxially arranged with the round hole is formed in the locking block. The push rod is moved to one side by the pushing structure, and the limiting column is driven to pass through the connecting groove from the middle annular locking groove into the annular locking groove on both sides. The pushing structure continues to run to rotate the push rod, so that the limiting column rotates in the annular locking groove and moves away from the connecting groove on one side, thereby locking the whole push rod. The push rod is locked after the gear is engaged, which does not affect the convenience of gear engagement operation, and ensures the driving stability and safety of the farm machinery.

Description

Technical Field

[0001] This invention relates to the field of agricultural machinery gearboxes, specifically to an agricultural machinery walking drive gearbox. Background Technology

[0002] The gearbox is the core component of the internal combustion engine transmission system. It changes the engine's output speed and torque by adjusting the gear combination to adapt to different driving conditions. When agricultural vehicles travel on uneven roads, the unevenness of the road surface will generate a large torsional vibration impact on the vehicle's output shaft. This impact is transmitted to the synchronizer sleeve through the output shaft. The synchronizer sleeve is softly locked by ball grooves. Large vibrations can cause the synchronizer sleeve to disengage from the engagement ring to a certain extent, resulting in the vehicle losing power. To address this issue, patent application CN117345865B provides a transmission shift lock assembly, transmission, and automobile. It uses a paddle inserted into a groove on the shift fork shaft, which improves the locking effect of the lock structure. Even if vibration occurs during driving, the paddle is not easy to disengage from the groove. Although the above structure can lock the shift fork shaft and prevent the vehicle from disengaging during driving, the groove on the shift fork shaft will cause stress concentration. Long-term operation will cause the shift fork shaft to break, which will seriously affect the service life of the shift fork shaft and the transmission. Moreover, the paddle needs to be pressed to lock during shifting, making shifting more complicated.

[0003] Therefore, a walking drive gearbox for agricultural machinery is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a walking drive gearbox for agricultural machinery, which solves the problem of locking the synchronizer sleeve of the gearbox while maintaining the ease of shifting and ensuring the service life of the gearbox without changing the shifting operation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] The utility model provides an agricultural machinery walking drive gearbox, including gearbox body, the push rod is connected with the shift paddle in the gearbox body, the round hole is set up on the gearbox body, the push rod passes through the round hole and extends to the outside of gearbox body, one side of the gearbox body is fixedly installed with the locking block, the through hole is set up in the locking block and is arranged coaxially with the round hole, the push rod extends to the through hole, a plurality of evenly arranged annular locking grooves are set up in the locking block, the through hole is arranged coaxially with the annular locking groove and penetrates the annular locking groove, a plurality of connecting grooves are set up in the locking block, the connecting groove connects two adjacent annular locking grooves, two symmetrical limit posts are installed on the push rod, the limit post is set up with the placement groove in the end away from the push rod, the gyro wheel is rotatably connected in the placement groove, the gyro wheel rolls in the annular locking groove, the push structure is installed on the push rod, when the gearbox switches gear, the push structure drives the limit post to pass through the connecting groove from the middle annular locking groove into the annular locking groove on both sides and rotates.

[0007] When the agricultural vehicle is running, a large torsional vibration impact will be generated on the output shaft of the vehicle due to the unevenness of the road surface when the vehicle passes through the uneven road surface. The impact is transmitted to the synchronizer sleeve through the output shaft, which causes the synchronizer sleeve and the combined gear ring to be separated to a certain extent, thereby causing the vehicle to lose power and affecting the stability and safety of the vehicle. To solve this problem, the design goal of the present application is to effectively lock the synchronizer sleeve after shifting under the premise of ensuring the shifting efficiency and stability of the gearbox, so as to avoid accidental disengagement of the synchronizer sleeve due to external impact or other factors. In addition, in the shifting process of the traditional gearbox, the shifting may fail due to problems such as improper shifting or loosening of the locking mechanism, which may even cause damage to the gearbox and seriously affect the normal operation and service life of the vehicle. The gearbox of the present design introduces key components such as annular locking grooves, connecting grooves and limiting columns, and these components work together to achieve more accurate and reliable shifting and locking functions. Specifically, after the limiting column is pushed into place, a certain rotation operation is required. This design enables the synchronizer sleeve to move accurately to the predetermined position after the push rod moves, thereby ensuring smooth and stable shifting process and effectively improving the overall performance and durability of the gearbox. In specific operation, the pushing structure pushes the push rod to move to one side and drives the limiting column on the push rod to move, so that the limiting column passes through the connecting groove from the middle annular locking groove into the annular locking groove on both sides. At this time, the push rod cannot continue to move, and the pushing structure cannot continue to push the push rod to move. The pushing structure will push the push rod to rotate, so that the limiting column rotates in the annular locking groove and moves away from the connecting groove on one side, thereby locking the entire push rod. Due to the design of the roller, the limiting column can reduce friction during rolling and improve the smoothness of shifting. Of course, the locking of the limiting column is only for the pushing force generated by the output shaft vibration on the push rod, and will not affect the normal operation of the gear shifting mechanism. After the gear shifting is completed, the push rod is locked to ensure the driving stability and safety of the agricultural machine.

[0008] Preferably, the pushing structure comprises a ball, the push rod is fixedly provided with a mounting ring, the ball is rollingly connected to the mounting ring, the push rod is slidably connected with a sleeve, the sleeve is slidably connected in the through hole, the mounting ring is slidably connected in the sleeve, the sleeve is provided with a guide groove, the guide groove is integrally provided in an S shape, the ball is rollingly connected in the guide groove, the two sides of the mounting ring are abutted with first compression springs, the other ends of the two first compression springs are respectively abutted with the two ends of the sleeve, the first compression spring is sleeved on the push rod, and the sleeve is connected with the shifting mechanism.

[0009] When the gearbox switches gears, the sleeve is driven by the shift mechanism to slide along the push rod. Since the guide groove is S-shaped as a whole, the ball will roll in the guide groove as the sleeve slides. However, the two sides of the mounting ring are abutted by the first compression spring, which pushes the ball with the sleeve for a certain time. This will first push the push rod to move to one side for gear engagement and drive the limiting column and the roller thereon to pass through the connecting groove into the annular locking groove on one side. When the push rod cannot move, the sleeve will compress the first compression spring, and the ball will roll in the guide groove. However, since the push rod cannot continue to move, the push rod will rotate at this time, which makes the limiting column swing away from the connecting groove on one side, thereby locking the push rod. This design enables the push rod to move smoothly and accurately to the predetermined position during gear shifting, and the sleeve resets under the action of the first compression spring, preparing for the next gear shifting. After the push rod is moved by the sleeve for gear engagement, the sleeve continues to move and rotate the push rod for locking, ensuring that the push rod can be locked in a certain position after completing the gear engagement. Through simple structure, the push rod can be effectively locked while ensuring quick and simple gear engagement, avoiding large torsional vibration impact of the vehicle when driving on a bumpy road, and the synchronous gear sleeve pushing the push rod to move and disengage from the coupling gear ring, resulting in loss of power of the vehicle. By locking the push rod after gear engagement, the driving stability and safety of the agricultural machine are ensured.

[0010] Preferably, the push rod is fixedly installed with a locking ring, the locking ring is provided with a plurality of sliding holes, the limiting column is slidingly connected in the sliding hole, and a second compression spring is installed in the sliding hole. The two ends of the second compression spring are respectively abutted with the inner wall of the sliding hole and the limiting column. The locking ring and the mounting ring are divided into upper and lower half rings and are connected by screws and fixed on the push rod.

[0011] The design of the roller at one end of the limiting column enables the limiting column to slide in the sliding hole when subjected to external force and reduces the friction of the limiting column. The elastic force of the second compression spring enables the limiting column to always push the roller against the inner wall of the annular locking groove, thereby ensuring that the limiting column can be stably clamped in the annular locking groove. In addition, the split design of the locking ring and the mounting ring facilitates installation and disassembly. It should be noted that the two half rings are installed in an upper-lower manner, so that the two limiting columns are symmetrically arranged above and below to avoid the gap of the limiting column and the locking block from overlapping each other. The locking ring and the mounting ring are installed by screws, which greatly improves the maintenance convenience of the gearbox.

[0012] Preferably, the cross section of the annular locking groove on both sides is a fan-shaped structure, the vertical edges of the fan-shaped structure on both sides are towards the middle annular locking groove, the length of the limiting column is a, the depth of the annular locking groove is b, and 0

[0013] When the limiting column slides into the annular locking groove, the vertical edges of the fan-shaped structure can effectively make the side wall of the annular locking groove against the limiting column, because the diameter of the limiting column is always smaller than the thickness of the annular locking groove, the limiting column can smoothly enter the annular locking groove, and the gap can make the limiting column shake, thereby causing the synchronizer sleeve to shake. The fan-shaped structure makes the limiting column driven by the roller tightly adhere to one side of the vertical edge after entering the annular locking groove, thereby realizing stable operation of the shifting mechanism. In addition, the depth of the annular locking groove is b, when b is equal to half of the overall length of the limiting column, the distance of the limiting column deep into the annular locking groove can withstand greater force and torque, and is not easy to break due to external force. However, at this time, the extrusion force on the annular locking groove and the force on the protrusion of the push rod are the same, so that the push rod is damaged to a certain extent. When b is less than half of the overall length of the limiting column, the overall length of the limiting column on the push rod increases the stress area, thereby avoiding damage to the push rod and ensuring the driving stability and safety of the agricultural machine.

[0014] Preferably, the distance between the two annular locking grooves is equal to the distance that the push rod drives the shift paddle to move to one side, and arc-shaped chamfers are arranged on both sides of the connecting groove, and the arc-shaped chamfers are asymmetrically arranged, and the radius of one side is half of the radius of the other side.

[0015] Such design makes the limiting column smoothly slide from one annular locking groove to another annular locking groove during the shifting operation of the shift paddle, reduces the jamming and resistance in the shifting process, and the design of the arc-shaped chamfer facilitates the entry and disengagement of the shift paddle. In addition, the radius of one side of the arc-shaped chamfer is half of the radius of the other side, so that the limiting column can more smoothly slide in the annular locking grooves on both sides during rotation, thereby reducing wear to a certain extent, prolonging the service life of the gearbox, ensuring smooth shifting of the agricultural machine during driving, and improving the comfort and safety of driving.

[0016] Preferably, a plurality of positioning holes are arranged in the annular locking grooves on both sides, the depth of the positioning hole is less than half of the radius of the roller, and when the roller enters the positioning hole, the ball moves to the vertex position of the guide groove.

[0017] At this time, the roller is firmly clamped in the positioning hole, the locking of the push rod is realized, and the stable gear shifting position of the gear shifting mechanism is ensured, the design not only improves the gear shifting accuracy of the gearbox, but also prevents the roller from rotating the push rod due to vibration or other external factors, thereby avoiding the push rod from being separated from the ring-shaped locking groove on one side due to accidental circumstances, and ensuring the driving stability and safety of the agricultural machine.

[0018] Preferably, the push rod is entirely made of metal material and is cast, and when the push rod is cast, two annular protrusions are formed on the surface of the push rod, which are located on both sides of the locking ring. The design of the two annular protrusions not only enhances the structural strength of the push rod, but also plays a limiting role on the locking ring, preventing the locking ring from moving axially on the push rod, thereby ensuring the stability of the connection between the locking ring and the push rod, avoiding the locking ring and the ring-shaped locking groove from limiting the push rod after the push rod is pushed, causing a certain amount of displacement of the push rod, and ensuring the overall locking of the push rod by the locking ring, ensuring that the agricultural vehicle can pass through the uneven road surface during driving and generate a large torsional vibration impact, and when the impact is transmitted to the synchronizer sleeve through the output shaft, the locking ring can limit the synchronizer sleeve through the pawl, avoiding the synchronizer sleeve and the combination gear from being separated, thereby ensuring the safe driving of the vehicle.

[0019] Preferably, a plurality of threaded holes are formed on one side of the gearbox body, the threaded holes are uniformly distributed around the circular hole, the locking block is composed of two parts and is installed on the threaded hole through a screw. The upper and lower parts of the locking block are compact in structure and reasonable in design, which can effectively increase the connection strength of the locking block and the gearbox. The threaded hole is not only convenient for the installation and disassembly of the locking block, but also ensures the stability of the locking block on the gearbox. In addition, the locking block is composed of two parts, which is convenient for the installation of internal parts. However, a certain gap will inevitably be generated when the two parts are combined, which will affect the rotation of the roller. Therefore, the upper and lower setting method is adopted when the two rollers are in the neutral position, and the rotation is limited to a certain angle, so as to avoid the rotation of the roller to the gap position, thereby ensuring the stable operation of the equipment.

[0020] Compared with the prior art, the beneficial effects of the present application are:

[0021] 1. The push structure pushes the push rod to move to one side, and drives the limiting column to pass through the connecting groove from the annular locking groove in the middle into the annular locking groove on both sides. The push structure continues to operate to rotate the push rod, so that the limiting column rotates in the annular locking groove and moves away from the connecting groove on one side, thereby locking the whole push rod. After the gear is hung, the push rod is locked, which does not affect the convenience of gear hanging operation, while ensuring the driving stability and safety of the agricultural machine.

[0022] 2. After the sleeve pushes the push rod to move and engage the gear, the sleeve continues to move and pushes the push rod to rotate and lock, ensuring that the push rod can be locked in a certain position after the gear engagement operation is completed. Through a simple structure, the push rod is effectively locked while ensuring fast gear engagement, preventing the synchronizer sleeve from disengaging from the engagement gear ring and causing the vehicle to lose power, thus ensuring the driving stability and safety of the agricultural machinery.

[0023] 3. Because the diameter of the limiting post is always smaller than the thickness of the annular locking groove, the limiting post can smoothly enter the annular locking groove. The resulting gap will cause the limiting post to wobble, which will cause the synchronizer sleeve to wobble. The fan-shaped structure allows the roller to drive the limiting post into the annular locking groove and keep it close to the vertical side. This prevents the push rod from causing the synchronizer sleeve to wobble slightly after the push rod is locked, thus ensuring the stability and safety of the agricultural machinery. Attached Figure Description

[0024] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0025] Figure 2 This is a schematic diagram of the internal structure of the locking block in this invention;

[0026] Figure 3 for Figure 2 Enlarged structural diagram at point A;

[0027] Figure 4 This is a three-dimensional structural diagram of the sleeve in this invention;

[0028] Figure 5 This is a schematic diagram of the internal structure of the sleeve in this invention;

[0029] Figure 6 This is a schematic diagram of the moving structure of the push rod in this invention;

[0030] Figure 7 This is a schematic diagram of the locking ring structure in this invention;

[0031] Figure 8 This is a schematic diagram of the positioning hole in the present invention.

[0032] In the diagram: 1. Gearbox body; 2. Locking block; 3. Through hole; 4. Push rod; 5. Sleeve; 6. Locking ring; 7. Annular protrusion; 8. Annular locking groove; 9. Connecting groove; 10. Limiting post; 11. Roller; 12. Guide groove; 13. Mounting ring; 14. Ball bearing; 15. First compression spring; 16. Arc-shaped chamfer; 17. Fan-shaped structure; 18. Sliding hole; 19. Second compression spring; 20. Placement groove; 21. Positioning hole. Detailed Implementation

[0033] Please seeFigures 1 to 8 The application provides an agricultural machinery walking driving gearbox, and has the following technical scheme:

[0034] The agricultural machinery walking driving gearbox comprises a gearbox body 1, a push rod 4 connected with a shifting piece in the gearbox body 1, a round hole formed in the gearbox body 1, the push rod 4 extending to outside of the gearbox body 1 through the round hole, a locking block 2 fixedly installed on one side of the gearbox body 1, a through hole 3 coaxially arranged with the round hole and formed in the locking block 2, the push rod 4 extending into the through hole 3, a plurality of annular locking grooves 8 uniformly arranged and formed in the locking block 2, the through hole 3 coaxially arranged with the annular locking grooves 8 and penetrating the annular locking grooves 8, a plurality of connecting grooves 9 formed in the locking block 2 and connecting two adjacent annular locking grooves 8, two symmetrical limiting columns 10 installed on the push rod 4, a placing groove 20 formed at one end of the limiting column 10 away from the push rod 4, a roller 11 rotatably connected in the placing groove 20 and rolling in the annular locking groove 8, a pushing structure installed on the push rod 4, when the gearbox switches gears, the pushing structure drives the limiting column 10 to pass through the connecting groove 9 from the middle annular locking groove 8 into the annular locking grooves 8 on the two sides and rotates.

[0035] The pushing structure comprises a ball 14, an installation ring 13 fixedly installed on the push rod 4, the ball 14 being rollingly connected to the installation ring 13, a sleeve 5 slidably connected to the push rod 4 and slidably connected in the through hole 3, the installation ring 13 being slidably connected in the sleeve 5, a guide groove 12 formed in the sleeve 5 and integrally arranged in an S shape, the ball 14 being rollingly connected to the guide groove 12, first compression springs 15 abutting against the two sides of the installation ring 13, the other ends of the two first compression springs 15 abutting against the two ends of the sleeve 5, the first compression springs 15 being sleeved on the push rod 4, and the sleeve 5 being connected with a gear shifting mechanism.

[0036] The push rod 4 is fixedly installed with a locking ring 6, a plurality of sliding holes 18 are formed in the locking ring 6, the limiting column 10 is slidably connected in the sliding hole 18, a second compression spring 19 is installed in the sliding hole 18, the two ends of the second compression spring 19 abutting against the inner wall of the sliding hole 18 and the limiting column 10, the locking ring 6 and the installation ring 13 are both divided into upper and lower half rings and arranged, the two half rings are connected by a screw and fixed on the push rod 4, the whole push rod 4 is casted by a metal material, when the push rod 4 is casted, two annular protrusions 7 are formed on the surface of the push rod 4, the annular protrusions 7 are located on the two sides of the locking ring 6, a plurality of threaded holes are formed in one side of the gearbox body 1 and uniformly distributed around the round hole, the locking block 2 is composed of two parts and installed on the threaded holes by a screw.

[0037] The cross section of the two side annular locking grooves 8 is a sector structure 17, the vertical edges of the two side sector structures 17 are towards the middle annular locking groove 8, the length of the limiting column 10 is 40mm, and the depth of the annular locking groove 8 is 18mm.

[0038] The distance between the two annular locking grooves 8 is equal to the distance of the push rod 4 driving the push piece to move to one side, the two sides of the connecting groove 9 are provided with arc chamfers 16, and the arc chamfers 16 are asymmetrically arranged, and the radius of the arc on one side is half of the radius of the arc on the other side.

[0039] A plurality of positioning holes 21 are arranged in the two side annular locking grooves 8, the depth of the positioning hole 21 is less than half of the radius of the roller 11, and when the ball 14 moves to the vertex position of the two sides of the guide groove 12, the roller 11 enters the positioning hole 21.

[0040] When used, the whole push rod 4 is casted by metal material, and two annular protrusions 7 are formed on the surface of the push rod 4 during casting, the specific position of the locking ring 6 is quickly installed through the annular protrusions 7, the upper half ring and the lower half ring of the locking ring 6 are inserted into the middle of the two annular protrusions 7, and it should be noted that the limiting column 10 is inserted into the sliding hole 18 and the second compression spring 19 is placed when the locking ring 6 is inserted, and the two half rings are fixed by screws, and it should be noted that the two limiting columns 10 are symmetrically arranged, so as to avoid the gap of the limiting column 10 and the locking block 2 from overlapping each other, the annular protrusion 7 can not only limit the locking block 2, but also help the installer to quickly install.

[0041] After the locking block 2 is installed, the lower half of the locking block 2 is installed on the gearbox body 1 by screws, the locking ring 6 is located in the middle annular locking groove 8, and the sleeve 5 on one side is slid in the locking block 2, and a certain gap will inevitably be generated when the two parts are combined, which will affect the rotation of the roller 11. Therefore, the two rollers 11 are arranged in an up-down manner when in the idle position, and the rotation is limited to a specific angle, so as to avoid the roller 11 from rotating to the gap position, and finally the upper half of the locking block 2 is covered on the lower half for the final installation, and after the locking block 2 is installed, the sleeve 5 is connected with the gear shifting mechanism.

[0042] When the shifting operation is performed, the sleeve 5 is pushed to move by the shifting mechanism, and due to the S-shaped guide groove 12, the ball 14 rolls in the guide groove 12 as the sleeve 5 slides. However, the two sides of the mounting ring 13 abut against the first compression spring 15, and the sleeve 5 pushes the ball 14 to move a certain distance through the first compression spring 15, which first pushes the push rod 4 to move to one side to perform the gear engagement operation and drives the limiting column 10 and the roller 11 thereon to pass through the connecting groove 9 and enter the annular locking groove 8 on one side. When the push rod 4 cannot move, the sleeve 5 will compress the first compression spring 15, and the ball 14 will roll in the guide groove 12. However, since the push rod 4 cannot continue to move, the push rod 4 will rotate at this time, which makes the limiting column 10 swing away from the connecting groove 9 on one side, thereby locking the push rod 4.

[0043] Of course, this design enables the push rod 4 to move smoothly and accurately to the predetermined position during the shifting process, and the sleeve 5 is reset under the action of the first compression spring 15, preparing for the next shifting. After the sleeve 5 pushes the push rod 4 to move and engage the gear, the sleeve 5 continues to move and push the push rod 4 to rotate and lock, which ensures that the push rod 4 can be locked in a certain position after completing the gear engagement operation. Through the simple structure, the push rod 4 can be effectively locked while ensuring that the gear engagement operation is fast and simple.

[0044] The connecting groove 9 is provided with an arc chamfer 16 on both sides, and the arc chamfer 16 is asymmetrically arranged, with the radius of one side being half of the radius of the other side. The limiting column 10 can smoothly slide from one annular locking groove 8 to the other annular locking groove 8, reducing the jamming and resistance during the shifting process. The design of the arc chamfer 16 not only facilitates the entry and disengagement of the shifting piece, but also enables the limiting column 10 to more smoothly slide in the annular locking grooves 8 on both sides during the rotation process, thereby reducing the wear to some extent and prolonging the service life of the gearbox.

[0045] Since the diameter of the limiting column 10 is always smaller than the thickness of the annular locking groove 8, the limiting column 10 can smoothly enter the annular locking groove 8. The gap generated will cause the limiting column 10 to shake, thereby causing the synchronizer sleeve to shake. When the limiting column 10 slides into the annular locking groove 8, the vertical edge of the fan-shaped structure 17 faces the middle, and the limiting column 10 can always push the roller 11 against the inner wall of the annular locking groove 8 through the elastic force of the second compression spring 19, which can effectively make the limiting column 10 abut against the side wall of the annular locking groove 8.

[0046] In addition, the depth of the annular locking groove 8 is b, when b is equal to half of the overall length of the limiting column 10, the distance of the limiting column 10 into the annular locking groove 8 can withstand greater force and torque, and is not prone to breakage due to external force, but at this time, the extrusion force on the annular locking groove 8 and the force on the protrusion of the push rod 4 are the same, so that the push rod 4 is damaged to a certain extent, and when b is less than half of the overall length of the limiting column 10, the overall length of the limiting column 10 on the push rod 4 is increased, the stress area is improved, the push rod 4 is prevented from being damaged, and the driving stability and safety of the agricultural machine are ensured.

[0047] The above describes one specific embodiment of the present application in detail in combination with the drawings, but the present application is not limited to the above described embodiments. For those skilled in the art, various changes, modifications, replacements and variations of the embodiments without departing from the principles and ideas of the present application shall still fall within the protection scope of the present application.

Claims

1. An agricultural machine walking driving gearbox, comprising a gearbox body (1), a push rod (4) is connected with a shift paddle in the gearbox body (1), characterized in that, The gear box body (1) is provided with a circular hole, the push rod (4) extends to the outside of the gear box body (1) through the circular hole, one side of the gear box body (1) is fixedly provided with a locking block (2), the locking block (2) is provided with a through hole (3) coaxially arranged with the circular hole, the push rod (4) extends into the through hole (3), the locking block (2) is provided with a plurality of annular locking grooves (8) arranged uniformly, the through hole (3) is coaxially arranged with the annular locking groove (8) and penetrates the annular locking groove (8), the locking block (2) is provided with a plurality of connecting grooves (9), the connecting grooves (9) connect two adjacent annular locking grooves (8), the push rod (4) is provided with two limit posts (10) symmetrically arranged, one end of the limit post (10) away from the push rod (4) is provided with a placing groove (20), the placing groove (20) is rotatably connected with a roller (11), the roller (11) rolls in the annular locking groove (8), the push rod (4) is provided with a push structure, when the gear box switches gears, the push structure drives the limit post (10) to pass through the connecting groove (9) from the middle annular locking groove (8) into the annular locking grooves (8) on both sides and rotates.

2. The farm machine walking drive gearbox according to claim 1, characterized in that, The push structure comprises a ball (14), the push rod (4) is fixedly provided with a mounting ring (13), the ball (14) is rollingly connected to the mounting ring (13), the push rod (4) is slidably connected with a sleeve (5), the sleeve (5) is slidably connected in the through hole (3), the mounting ring (13) is slidably connected in the sleeve (5), the sleeve (5) is provided with a guide groove (12), the guide groove (12) is integrally provided in an S shape, the ball (14) is rollingly connected to the guide groove (12), the two sides of the mounting ring (13) are abutted with first compression springs (15), the other ends of the first compression springs (15) on the two sides are respectively abutted with the two ends of the sleeve (5), the first compression springs (15) are sleeved on the push rod (4), and the sleeve (5) is connected with a gear shifting mechanism.

3. The farm machine walking drive gearbox according to claim 2, characterized in that, The push rod (4) is fixedly provided with a locking ring (6), the locking ring (6) is provided with a plurality of sliding holes (18), the limit post (10) is slidably connected in the sliding hole (18), the sliding hole (18) is provided with a second compression spring (19), the two ends of the second compression spring (19) are respectively abutted with the inner wall of the sliding hole (18) and the limit post (10), the locking ring (6) and the mounting ring (13) are both divided into upper and lower half rings and arranged, and the two half rings are connected and fixed on the push rod (4) through screws.

4. The farm machine walking drive gearbox according to claim 2, characterized in that, The cross sections of the annular locking grooves (8) on the two sides are fan-shaped structures (17), the vertical edges of the fan-shaped structures (17) on the two sides are all directed to the middle annular locking groove (8), the length of the limit post (10) is a, the depth of the annular locking groove (8) is b, and 0 5. The farm machine walking drive gearbox according to claim 4, characterized in that, The distance between the two ring-shaped locking grooves (8) is equal to the distance of the push rod (4) driving the push piece to move to one side, the two sides of the connecting groove (9) are provided with arc chamfers (16), and the arc chamfers (16) are asymmetrically arranged, and the radius of the arc on one side is half of the radius of the arc on the other side.

6. The farm machine walking drive gearbox according to claim 3, characterized in that, A plurality of positioning holes (21) are arranged in the two ring-shaped locking grooves (8), the depth of the positioning hole (21) is less than half of the radius of the roller (11), and when the ball (14) moves to the vertex position of the two sides of the guide groove (12), the roller (11) enters the positioning hole (21).

7. The farm machine walking drive gearbox according to claim 3, characterized in that, The whole of the push rod (4) is casted by metal material, and when the push rod (4) is casted, two annular protrusions (7) are formed on the surface of the push rod (4), and the annular protrusions (7) are located on the two sides of the locking ring (6).

8. The farm machine walking drive gearbox according to claim 3, characterized in that, A plurality of threaded holes are arranged on one side of the gearbox body (1), the threaded holes are uniformly distributed around the circular hole, the locking block (2) is composed of two parts, and is installed on the threaded hole through a screw.

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