A tractor gear shift mechanism

Abstract

This utility model provides a tractor shifting mechanism, relating to the technical field of shifting equipment. It includes an input shaft, an output shaft, and a reverse shaft, all rotatably mounted inside a gearbox. The surface of the input shaft is provided with multiple input gears, and the surfaces of the output shaft and reverse shaft are each provided with output gears. It also includes an adjustment unit, which can adjust the meshing of different input and output gears on the output shaft to adjust the transmission ratio. In this utility model, the oil outlet opening at the bottom of the internal cavity of the shift lever directly faces the inner wall of the shift paddle's groove, and the oil outlet is angled. This allows the lubricating oil squeezed out by the lubricating plug to flow precisely to the sliding contact between the shift lever and the groove, avoiding oil waste or failure to reach critical friction points due to flow deviation.

Description

Technical Field

[0001] This utility model relates to the field of gear shifting equipment technology, and in particular to a gear shifting mechanism for a tractor. Background Technology

[0002] The tractor shifting mechanism is a core component of the tractor's transmission system. Its main function is to change the transmission ratio by adjusting the meshing relationship of the gears between the input and output shafts, thereby enabling the tractor to switch between different travel speeds and reverse gear, adapting to the power requirements of different working conditions such as field cultivation and transportation. Existing tractor shifting mechanisms typically include core components such as the input shaft, output shaft, reverse gear shaft, gear set (including input and output gears), adjusting components (such as shift forks and shift fork shafts), and shift lever. The input bearing receives engine power and drives the input gear on it to rotate. The output shaft obtains power through the selective meshing of the output and input gears and transmits it to the travel system. The reverse gear shaft transmits power in the reverse direction through the reverse gear. The adjusting components work in conjunction with the shift lever to drive the gears to slide axially to complete the shifting action.

[0003] However, existing tractor shifting mechanisms still have many problems affecting performance and lifespan in actual use: the sliding contact between the shift lever and the shift paddle is the key friction point for shifting operation. Existing mechanisms mostly rely on manual application of lubricating oil to the outside periodically, but tractor operating environments are mostly dusty and muddy scenes such as fields and construction sites. The externally applied lubricating oil is easily contaminated by impurities and has difficulty penetrating into the gap between the shift lever and the paddle slide groove. Utility Model Content

[0004] The purpose of this utility model is to address the shortcomings of existing technologies by proposing a tractor gear shifting mechanism.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a tractor shifting mechanism, including an input shaft, an output shaft, and a reverse shaft, wherein the input shaft, output shaft, and reverse shaft are all rotatably mounted inside a gearbox, the surface of the input shaft is provided with multiple input gears, and the surfaces of the output shaft and the reverse shaft are provided with output gears, and further includes an adjustment part, wherein the adjustment part can adjust the meshing of different input gears and output gears on the output shaft to adjust the transmission ratio.

[0006] Preferably, the surface of the output shaft is provided with a first stepped gear and a second stepped gear, both of which can slide along the axial direction of the output shaft, and the first stepped gear and the second stepped gear cannot rotate with the output shaft.

[0007] Preferably, the surface of the input shaft is provided with a first shift gear and a second shift gear, wherein there are two first shift gears, which are respectively located on both sides of the first stepped gear, and there are two second shift gears, which are respectively located on both sides of the second stepped gear.

[0008] Preferably, the adjusting unit includes three shift fork shafts, which are slidably mounted inside the gearbox. Shift forks are fixedly connected to the surfaces of the shift fork shafts. The three shift forks respectively engage with the surfaces of the first stepped gear, the second stepped gear, and the reverse gear. From right to left, the three shift fork shafts are designated as shift fork shaft number one, shift fork shaft number two, and shift fork shaft number three. Shift fork shaft number one slides left and right, driving the shift fork. The shift fork drives the first stepped gear to slide along the output shaft. By switching the engagement of the first stepped gear and the two first shift gears, different gear ratios are adjusted to regulate the output shaft speed. Shift fork shaft number two slides left and right, driving the shift fork. The shift fork drives the second-stage gear to slide along the output shaft. By switching the engagement of the second-stage gear and two second shift gears, different gear ratios are adjusted to regulate the speed of the output shaft. The third shift fork shaft slides left and right, driving the shift fork. The shift fork drives the reverse gear to mesh with the first-stage gear, thereby causing the reverse shaft to rotate and output power. It should be noted that if any one of the first, second, and third shift fork shafts is in a working state, the other two are in their initial positions. The shift fork shafts are fixedly equipped with shift paddles at their ends, and also include a shift lever. The shift lever can rotate at multiple angles on the tractor frame, and the shift lever can slide inside the shift paddles.

[0009] Preferably, the gear shift lever has a placement cavity inside, and the bottom end of the placement cavity is connected to an oil outlet, wherein the oil outlet faces the gear shift paddle.

[0010] Preferably, the placement cavity has an installation hole inside, and a lubricating plug is provided inside the placement cavity. The lubricating plug has a cavity inside, and a cap is installed at the port of the lubricating plug. The lubricating plug can be threadedly connected to the installation hole. The lubricating plug contains lubricating oil. Squeezing the lubricating plug allows the lubricating oil to be squeezed out from the tip of the lubricating plug. A sleeve is threaded on the surface of the shift lever, and the sleeve can block the placement cavity.

[0011] Compared with the prior art, the advantages and positive effects of this utility model are as follows:

[0012] 1. In this utility model, the oil outlet at the bottom of the internal cavity of the shift lever faces directly toward the inner wall of the shift paddle's groove, and the oil outlet is set at an angle. This allows the lubricating oil squeezed out by the lubricating plug to flow precisely to the sliding contact between the shift lever and the groove, avoiding the waste of lubricating oil due to flow deviation or failure to reach key friction parts. This ensures that the sliding contact between the shift lever and the shift paddle is always in an effective lubrication state, reducing the frictional resistance when the two slide relative to each other from the root.

[0013] 2. This utility model features convenient oil replenishment and long-term oil storage capabilities, reducing the difficulty of lubrication maintenance: the lubrication plug has an oil storage cavity inside, which can be pre-filled with lithium-based grease (resistant to high and low temperatures, highly water-resistant, and suitable for complex working conditions of tractors). When replenishing oil, there is no need to disassemble the shifting mechanism; simply unscrew the cap and squeeze the lubrication plug to complete the oil supply, making the operation simple and efficient. At the same time, the oil storage cavity can achieve long-term storage of lubricating oil, reducing the frequency of frequent oil replenishment and lowering the user's maintenance workload and time costs. Attached Figure Description

[0014] Figure 1 A three-dimensional structural diagram of a tractor shifting mechanism is provided for this utility model;

[0015] Figure 2 This utility model proposes a tractor gear shifting mechanism. Figure 1 Another angle diagram;

[0016] Figure 3 This utility model provides a partial schematic diagram of the shift lever in a tractor shifting mechanism;

[0017] Figure 4 This utility model provides a schematic diagram of the first gear switching state in a tractor gear shifting mechanism;

[0018] Figure 5 This utility model provides a schematic diagram of the second gear switching state in a tractor gear shifting mechanism;

[0019] Figure 6 This utility model provides a schematic diagram of the switching state of three gears in a tractor gear shifting mechanism;

[0020] Figure 7 This utility model provides a schematic diagram of the four-gear switching state in a tractor gear shifting mechanism;

[0021] Figure 8 This utility model provides a schematic diagram of the reverse gear switching state in a tractor gear shifting mechanism.

[0022] Legend: 1. Adjustment section; 101. Shift fork shaft; 102. Shift fork; 2. Input shaft; 3. First step gear; 4. First shift gear; 5. Second shift gear; 6. Second step gear; 7. Output shaft; 8. Reverse shaft; 9. Reverse gear; 10. Shift paddle; 11. Shift lever; 12. Placement cavity; 13. Mounting hole; 14. Sleeve; 15. Lubrication plug; 16. Cover; 17. Oil outlet. Detailed Implementation

[0023] Example 1, as Figure 1-8As shown, a tractor shifting mechanism is integrally assembled within the tractor's gearbox housing. The gearbox housing is a closed structure made of cast iron, with pre-drilled holes for mounting various shaft components and cavities for accommodating gear transmission, ensuring that the shifting mechanism is not affected by external impurities during operation and can stably transmit power. The input shaft 2, output shaft 7, and reverse shaft 8 are all parallel and spaced apart along the length of the gearbox housing. The two ends of the input shaft 2 are rotatably mounted in holes on both sides of the gearbox housing via deep groove ball bearings. The inner ring of the deep groove ball bearing has an interference fit with the input shaft 2, while the outer ring has a transition fit with the hole in the gearbox housing. This assembly method ensures that the input shaft 2 can rotate freely while also withstanding a certain radial load. Multiple input gears are spaced axially along the outer peripheral wall of the input shaft 2. These input gears are specifically a first shift gear 4 and a second shift gear 5. Both the first shift gear 4 and the second shift gear 5 are fixedly connected to the input shaft 2 via a flat key. The two sides of the flat key are tightly fitted with the keyways on the input shaft 2 and the keyways in the gear inner holes, respectively, ensuring that the input shaft 2 can synchronously drive the first shift gear 4 and the second shift gear 5 to rotate without relative slippage. The output shaft 7 is installed in the same way as the input shaft 2. Its two ends are also rotatably mounted in corresponding holes in the gearbox housing via deep groove ball bearings. A first stepped gear 3 and a second stepped gear 6 are fitted onto the outer peripheral wall of the output shaft 7. The inner holes of the first stepped gear 3 and the second stepped gear 6 are machined with rectangular splines. Matching rectangular splines are also machined on the corresponding positions of the outer peripheral wall of the output shaft 7. Through the cooperation of the rectangular splines, the first stepped gear 3 and the second stepped gear 6 can slide bidirectionally along the axial direction of the output shaft 7, and can also rotate synchronously with the output shaft 7 when it rotates, without relative circumferential displacement. The reverse gear shaft 8 is also rotatably mounted on the gearbox housing via bearings at both ends. A reverse gear 9 is fitted on its outer peripheral wall. The reverse gear 9 is also connected to the reverse gear shaft 8 by a rectangular spline, allowing the reverse gear 9 to slide along the axial direction of the reverse gear shaft 8 and rotate synchronously with the reverse gear shaft 8. The adjustment unit 1, as the core component for realizing the shifting function, includes three shift fork shafts 101 and three shift forks 10. The three shift fork shafts 101 are parallel and spaced apart along the width direction of the gearbox housing. The shift fork shafts 101 are made of 45# steel, and their outer peripheral walls are chrome-plated with a chrome plating layer thickness of 0.05~0.1mm to improve the surface hardness and wear resistance of the shift fork shafts 101 and reduce frictional loss during sliding. Each shift fork shaft 101 is slidably inserted into a pre-set guide hole in the side wall of the gearbox housing. A copper sleeve is embedded in the guide hole, and there is a clearance fit between the copper sleeve and the shift fork shaft 101. The clearance is controlled between 0.02 and 0.05 mm to ensure that the shift fork shaft 101 can slide smoothly in the guide hole without excessive shaking.Three shift forks 10 are fixed to the outer peripheral walls of three shift fork shafts 101 one-to-one by welding. The welding joints use fillet welds, and the weld height is determined according to the diameter of the shift fork shaft 101 to ensure the connection strength between the shift fork 10 and the shift fork shaft 101. The fork of each shift fork 10 mates with the annular groove of the corresponding gear. Specifically, the fork of the first shift fork 10 is engaged in the annular groove of the first stepped gear 3, the fork of the second shift fork 10 is engaged in the annular groove of the second stepped gear 6, and the fork of the third shift fork 10 is engaged in the annular groove of the reverse gear 9. The clearance between the fork and the annular groove is controlled at 0.1 to 0.2 mm to ensure that the shift fork 10 can stably drive the corresponding gear to slide axially without jamming. Along the right to left direction of the gearbox housing, the three shift fork shafts 101 are sequentially designated as shift fork shaft 1, shift fork shaft 2, and shift fork shaft 3. Each shift fork shaft 101 has a vertically fixed paddle shifter 102 at its exposed port extending outside the gearbox housing. The paddle shifter 102 is made of Q235 steel plate and is formed by stamping. Its surface is polished to remove burrs and sharp edges. A rectangular groove extending along its length is provided on the paddle shifter 102. The width of the groove is slightly larger than the diameter of the shift lever 11 to ensure that the shift lever 11 can slide smoothly in the groove. The shift lever 11 is rotatably mounted on the tractor frame via a hinged seat. The hinged seat is made of gray cast iron and has a through hole for mounting the shift lever 11. A wear-resistant bushing made of tin bronze is embedded in the through hole. After passing through the wear-resistant bushing, the shift lever 11 is hinged to the hinged seat via a pin. Both ends of the pin are fixed with cotter pins to prevent the pin from falling off. This structural design allows the shift lever 11 to swing flexibly around the hinge point at multiple angles. The lower end of the shift lever 11 is slidably embedded in the rectangular groove of the shift paddle 102. When the shift lever 11 is swung, the lower end of the shift lever 11 can slide in the groove and drive the shift paddle 102 to move synchronously, thereby pushing the shift fork shaft 101 to slide along its axial direction. The gear shift lever 11 has an axially extending placement cavity 12 inside. The placement cavity 12 is formed by drilling a hole in a deep hole drilling machine during the processing of the gear shift lever 11. The bottom end of the placement cavity 12 has an oil outlet 17 that penetrates the side wall of the gear shift lever 11. The oil outlet 17 is an obliquely arranged round hole with its axis forming an angle of 30-45 degrees with the axis of the gear shift lever 11. The opening direction of the oil outlet 17 is directly facing the inner wall of the slide groove of the gear shift paddle 102, ensuring that the lubricating oil delivered later can flow accurately to the sliding fit between the gear shift lever 11 and the slide groove. The side wall of the placement cavity 12 is provided with a mounting hole 13 along the radial direction of the shift lever 11. The inner wall of the mounting hole 13 is machined with an internal thread. A lubricating plug 15 is installed in the placement cavity 12. The lubricating plug 15 is made of nitrile rubber, which has good elasticity and oil resistance. The outer wall of the lubricating plug 15 is machined with an external thread that matches the internal thread of the mounting hole 13. The lubricating plug 15 and the mounting hole 13 are fixedly assembled through the threaded connection.The lubricating plug 15 has an axially oriented oil reservoir cavity for storing lubricating oil. This cavity is filled with lithium-based grease, which has excellent high-temperature resistance and water resistance, adapting to the tractor's operating conditions. A cap 16 is detachably fitted to the outer end of the lubricating plug 15. The cap 16 is made of polypropylene plastic, and its inner wall is also threaded. This threaded connection effectively prevents external dust and impurities from entering the oil reservoir cavity and contaminating the lubricating oil. The outer peripheral wall of the shift lever 11 is machined with external threads, and a sleeve 14 is fitted onto the thread. The sleeve 14 is made of brass and has good wear resistance and corrosion resistance. The inner wall of the sleeve 14 is machined with internal threads that match the external threads of the shift lever 11. By rotating the sleeve 14, it can be moved along the axial direction of the shift lever 11. When it is necessary to protect the placement cavity 12, the sleeve 14 can be rotated to cover the opening of the placement cavity 12 to prevent impurities from entering the placement cavity 12. When it is necessary to add lubricating oil, simply rotate the sleeve 14 in the opposite direction to expose the opening of the placement cavity 12.

[0024] Beneficial effects: When the shifting mechanism of this tractor is working, the power is first transmitted from the engine of the tractor to the input shaft 2, which drives the input shaft 2 to rotate synchronously. When the input shaft 2 rotates, it will drive the first shift gear 4 and the second shift gear 5 on it to rotate together through the key connection. At this time, the shift lever 11 can be operated to switch between different gears. When it is necessary to switch to first gear, swing the shift lever 11 to the left. The shift lever 11 swings around the hinge point of the hinge seat, and its lower end slides in the groove of the shift paddle 102 corresponding to the first shift fork shaft, driving the shift paddle 102 to move to the left. The shift paddle 102 drives the first shift fork shaft to slide to the left along the axial direction. The shift fork 10 on the first shift fork shaft moves to the left along the same direction, thereby pushing the first stepped gear 3 to slide to the left along the axial direction of the output shaft 7 until the first stepped gear 3 is fully engaged with the first shift gear 4 located to its left. At this time, the rotating first shift gear 4 will drive the first stepped gear 3 to rotate synchronously. The first stepped gear 3 drives the output shaft 7 to rotate through the spline connection. The output shaft 7 transmits power to the tractor's travel system to realize the power output at the first gear speed. When shifting to second gear, swing the shift lever 11 to the right. This causes the first shift fork to slide to the right, and the shift fork 10 pushes the first stepped gear 3 to slide to the right along the output shaft 7, engaging the first stepped gear 3 with the first shift gear 4 located to its right. Power is then transmitted to the output shaft 7 via the input shaft 2, the right-side first shift gear 4, and the first stepped gear 3, achieving second-gear speed output. When shifting to third gear, swing the shift lever 11 forward or backward (depending on the actual layout). This causes the shift paddle 102 corresponding to the second shift fork shaft to move, pushing the second shift fork shaft to slide to the left. The shift fork 10 on the second shift fork shaft pushes the second stepped gear 6 to slide to the left along the output shaft 7, engaging the second stepped gear 6 with the second shift gear 5 located to its left. Power is then transmitted to the output shaft 7 via the input shaft 2, the left-side second shift gear 5, and the second stepped gear 6, achieving third-gear speed output. When shifting to fourth gear, the reverse-swinging shift lever 11 drives the second shift fork to slide to the right. The shift fork 10 pushes the second step gear 6 to slide to the right and engages with the second shift gear 5 on the right side. Power is transmitted along the corresponding path to achieve fourth gear speed output. When shifting to reverse gear, the shift lever 11 moves the shift paddle 102 corresponding to the third shift fork shaft, causing the third shift fork shaft to slide axially. The shift fork 10 on the third shift fork shaft pushes the reverse gear 9 to slide axially along the reverse gear shaft 8 until the reverse gear 9 is fully engaged with the first step gear 3. At this time, the rotation of the first step gear 3 will drive the reverse gear 9 to rotate. The reverse gear 9 drives the reverse gear shaft 8 to rotate through the spline connection. The reverse gear shaft 8 transmits reverse power to the output shaft 7 (specifically, the reverse can be achieved through gear transmission between the reverse gear shaft 8 and the output shaft 7; this is a conventional reverse power transmission design), ultimately realizing the reverse driving of the tractor.Throughout the shifting process, because the shift paddle grooves of the three shift fork shafts are staggered, and the shift lever 11 can only engage with the groove of one shift paddle at a time to drive the corresponding shift fork shaft to slide, only one of the three shift fork shafts is always in the working state, while the other two remain in their initial positions. This effectively avoids gear damage caused by multiple gears meshing simultaneously. Furthermore, when there is insufficient lubrication at the sliding engagement point between the shift lever 11 and the shift paddle 102, the cap 16 can be unscrewed, and the lubrication plug 15 can be squeezed. This allows the lithium-based grease in the oil reservoir cavity of the lubrication plug 15 to be squeezed from its tip into the placement cavity 12. The grease then flows along the placement cavity 12 to the oil outlet 17, and through the oil outlet 17, it flows to the engagement point between the inner wall of the groove and the shift lever 11, achieving lubrication and ensuring that the shifting operation is always flexible and smooth.

[0025] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model in any other way. Any person skilled in the art may use the disclosed technical content to make changes or modifications to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this utility model, without departing from the scope of the utility model's technical solution, still fall within the protection scope of this utility model's technical solution. In the description of this utility model, it should be noted that, 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. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood through specific circumstances.

Claims

1. A tractor shifting mechanism, comprising an input shaft (2), an output shaft (7), and a reverse gear shaft (8), characterized in that: The input shaft (2), output shaft (7) and reverse gear shaft (8) are all rotatably mounted inside the gearbox. The surface of the input shaft (2) is provided with multiple input gears, and the surfaces of the output shaft (7) and reverse gear shaft (8) are provided with output gears. The gearbox also includes an adjustment part (1), which can adjust the meshing of different input gears and output gears on the output shaft (7) to adjust the transmission ratio.

2. The tractor shifting mechanism according to claim 1, characterized in that: The surface of the output shaft (7) is provided with a first stepped gear (3) and a second stepped gear (6). Both the first stepped gear (3) and the second stepped gear (6) can slide along the axial direction of the output shaft (7). The first stepped gear (3) and the second stepped gear (6) cannot rotate with the output shaft (7).

3. The tractor shifting mechanism according to claim 2, characterized in that: The surface of the input shaft (2) is provided with a first shift gear (4) and a second shift gear (5), wherein there are two first shift gears (4), which are located on both sides of the first stepped gear (3), and there are two second shift gears (5), which are located on both sides of the second stepped gear (6).

4. The tractor shifting mechanism according to claim 3, characterized in that: The adjustment unit (1) includes three shift fork shafts (101), which are slidably installed inside the gearbox. Shift forks (102) are fixedly connected to the surface of each shift fork shaft (101), and the three shift forks (102) are respectively engaged with the surfaces of the first step gear (3), the second step gear (6), and the reverse gear (9).

5. The tractor shifting mechanism according to claim 4, characterized in that: The shift fork shaft (101) is fixedly mounted with a shift paddle (10) and also includes a shift lever (11), wherein the shift lever (11) can rotate at multiple angles on the tractor frame and the shift lever (11) can slide inside the shift paddle (10).

6. The tractor shifting mechanism according to claim 5, characterized in that: The gear shift lever (11) has a placement cavity (12) inside, and the bottom end of the placement cavity (12) is connected to an oil outlet (17), wherein the oil outlet (17) faces the gear shift paddle (10).

7. The tractor shifting mechanism according to claim 6, characterized in that: The placement cavity (12) has an installation hole (13) inside, and a lubricating plug (15) is provided inside the placement cavity (12). The lubricating plug (15) has a cavity inside, and a cap (16) is installed at the port of the lubricating plug (15). The lubricating plug (15) can be threadedly connected to the installation hole (13). The lubricating plug (15) contains lubricating oil. Squeezing the lubricating plug (15) can squeeze the lubricating oil out from the tip of the lubricating plug (15). The surface of the shift lever (11) is threaded with a sleeve (14), and the sleeve (14) can block the placement cavity (12).

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