Transmission system for tractor and working method of transmission system

Abstract

The invention discloses a transmission system for a tractor and a working method of the transmission system, solves the problem that in the prior art, positive correlation between the rotating speed of a PTO output end and the vehicle speed cannot be achieved, and has the beneficial effect that the rotating speed of the PTO output end is selectively related to the rotating speed of an engine or the output vehicle speed. Comprising a first shaft and a second shaft, the first shaft is directly connected with an engine, the second shaft is an output shaft of the continuously variable transmission, a first synchronizer is arranged at the output end of the first shaft and fixedly connected with a third shaft, a fourth shaft is arranged on the other side of the second synchronizer and fixedly connected with the fourth shaft, and a first gear pair is arranged between the second shaft and the third shaft. A first gear in the first gear pair is sleeved on the third shaft and can rotate relative to the third shaft, a second gear in the first gear pair is fixedly connected with the second shaft, a second gear pair is arranged between the third shaft and the fourth shaft, and a fourth gear in the second gear pair is sleeved on the fourth shaft and can rotate relative to the fourth shaft.

Description

Technical Field

[0001] The present invention relates to the technical field of tractors, in particular to a transmission system for a tractor and a working method thereof. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Tractors are generally designed with a power take-off system PTO (PTO: Power Take-off, a device for power output) at the rear end of the rear axle to provide power to agricultural equipment such as rotary tillers, balers, and seeders. Usually, 1 to 3 PTO gears are set at the rear end of the tractor's rear axle. The PTO input shaft is directly connected to the engine, and each gear has a fixed transmission ratio relationship with the engine speed. The driver or user adjusts the PTO output speed by selecting different gears, so that the tractor PTO speed is positively correlated with the engine speed.

[0004] For some special agricultural working conditions, the PTO speed will directly affect its agronomic characteristics. For example, in sowing and fertilizing, the PTO speed will directly affect the sowing amount and fertilizer concentration. At this time, the PTO speed needs to change in real time according to the vehicle speed. Otherwise, it will lead to uneven sowing amount or fertilizer concentration, affecting the agronomic characteristics. The inventors found that in the prior art, there is no fixed transmission ratio relationship between the PTO speed and the vehicle speed of the tractor. In actual operation, the tractor speed will often fluctuate due to load changes. The PTO speed cannot change with the vehicle speed in real time, resulting in the inability to meet the needs of special working conditions, which is easy to affect the operation of the tractor. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a transmission system for a tractor, in which the engine speed can be stably maintained, so that the tractor has multiple working modes, and in some working modes, the PTO output end speed can be positively correlated with the vehicle speed.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A transmission system for a tractor, comprising a first shaft and a second shaft, the first shaft being directly connected to an engine, the second shaft being an output shaft of a continuously variable transmission, a first synchronizer being arranged at an output end of the first shaft, the first synchronizer being fixedly connected to a third shaft, a second synchronizer being arranged at an output end of the second shaft, the second synchronizer being fixedly connected to a fourth shaft, a first gear pair being arranged between the second shaft and the third shaft, a first gear in the first gear pair being sleeved on the third shaft and being rotatable relative to the third shaft, a second gear in the first gear pair being fixedly connected to the second shaft, a second gear pair being arranged between the fourth shaft and the third shaft, a third gear in the second gear pair being sleeved on the third shaft and being rotatable relative to the third shaft, the first gear and the third gear being rotatable synchronously, a fourth gear in the second gear pair being sleeved on the fourth shaft and being rotatable relative to the fourth shaft, the first synchronizer being able to be respectively combined with the first shaft or the first gear or to be kept in neutral, and the second synchronizer being able to be respectively combined with the second gear or the fourth gear or to be kept in neutral;

[0008] A PTO clutch is arranged at the output end of the third shaft, the PTO clutch is connected to the fifth shaft, and the output end of the fifth shaft is connected to the PTO output end through a transmission component.

[0009] In the transmission system for a tractor as described above, the third shaft supports the first gear and the third gear respectively through the first rotary bearing, so that the first gear and the third gear can rotate synchronously relative to the third shaft;

[0010] The fourth shaft supports the fourth gear via a second rotating bearing, ensuring that the fourth gear can rotate relative to the fourth shaft.

[0011] A transmission system for a tractor as described above, wherein the third shaft also supports the first transition gear through the first rotating bearing, the first transition gear, the first gear, and the third gear are fixedly connected through the first rotating bearing, the first transition gear is located on one side of the first synchronizer, the first synchronizer can be combined with the first transition gear, and when the first synchronizer is combined with the first transition gear, the first synchronizer can realize synchronous rotation with the first gear and the third gear;

[0012] The fourth shaft also supports the fourth transition gear through the second rotating bearing, so that the fourth transition gear is fixedly connected to the fourth gear, the fourth transition gear is located on one side of the second synchronizer, the second synchronizer can be combined with the fourth transition gear, and when the second synchronizer is combined with the fourth transition gear, the second synchronizer and the fourth gear can be rotated synchronously;

[0013] The second shaft is fixedly connected to the second transition gear and the second gear. The second transition gear is located on one side of the second synchronizer. The second synchronizer can be combined with the second transition gear to achieve synchronous rotation of the second synchronizer, the second shaft and the second gear. A third transition gear is arranged at the output end of the first shaft, and the first synchronizer is combined with the first shaft through the third transition gear.

[0014] A transmission system for a tractor as described above, wherein the output end of the fourth shaft is connected to the rear axle structure, and the fourth shaft is connected to the front axle structure via a transmission assembly;

[0015] The transmission assembly includes a fifth gear fixedly connected to the fourth shaft, the fifth gear is meshed with the sixth gear, and the sixth gear is connected to the front axle structure through the sixth shaft.

[0016] A transmission system for a tractor as described above, in order to realize that the PTO output end has multiple gears, the fifth shaft is provided with a third synchronizer, the third synchronizer is fixedly connected to the fifth shaft, the fifth shaft is located on one side of the third synchronizer and a seventh gear is provided, the seventh gear rotates synchronously with the fifth transition gear, the seventh gear is rotatable relative to the fifth shaft, the seventh gear is meshed with the eighth gear, and the eighth gear is connected to the PTO output end through the seventh shaft;

[0017] The fifth shaft is located on the other side of the third synchronizer and a ninth gear is set. The ninth gear rotates synchronously with the sixth transition gear and is rotatable relative to the fifth shaft. The ninth gear is meshed with the tenth gear, and the tenth gear is connected to the PTO output end through the seventh shaft.

[0018] In a second aspect, the present invention further provides a working method of a tractor transmission system, comprising the following contents:

[0019] First PTO mode: In this mode, the first synchronizer is combined with the first shaft. At this time, a part of the engine input power is transmitted to the second shaft through the continuously variable transmission. The second synchronizer can select high and low gears. When the second synchronizer is in low gear, it is directly combined with the second shaft, and a part of the engine input power is directly transmitted to the front axle structure and the rear axle structure through the second shaft-second synchronizer-fourth shaft. When the second synchronizer is in high gear, the second synchronizer is combined with the fourth gear, and a part of the engine input power is transmitted to the front axle structure and the rear axle structure by the second shaft-first gear pair-second gear pair-second synchronizer-fourth shaft.

[0020] As described above, a working method of a tractor transmission system, in the first PTO mode, another part of the engine power and speed is transmitted to the PTO clutch and the third synchronizer via the first synchronizer and the third shaft, and the third synchronizer can select different PTO gears, which are transmitted to the PTO output end through the third synchronizer-seventh gear-eighth gear or transmitted to the PTO output end through the third synchronizer-ninth gear-tenth gear.

[0021] The working method of the tractor transmission system as described above also includes the following contents:

[0022] Ground speed PTO mode: The first synchronizer is combined with the first gear. At this time, the engine input power is transmitted to the second synchronizer through the continuously variable transmission. The second synchronizer can select high and low gears. When the second synchronizer is in low gear, it is directly combined with the second shaft. A part of the engine input power is directly transmitted to the front and rear axle structures through the second shaft-second synchronizer-fourth shaft; the other part of the engine input power and speed are transmitted to the output end via the first gear pair-first synchronizer-third shaft-PTO clutch;

[0023] The second synchronizer is combined with the fourth gear in high gear, and part of the engine input power is transmitted to the front axle and rear axle structure via the second shaft-first gear pair-second gear pair-second synchronizer-fourth shaft, and the other part of the engine input power is transmitted to the PTO output end via the second shaft-first gear pair-first synchronizer-third shaft-PTO clutch.

[0024] The working method of the tractor transmission system as described above also includes the following contents:

[0025] PTO reverse mode: The second shaft is in reverse gear through the continuously variable transmission. At the same time, the second synchronizer is in the middle neutral position, the first synchronizer is combined with the first gear, and the engine input power and speed are transmitted to the PTO output end through the second shaft-first gear pair-first synchronizer-third shaft-PTO clutch. At this time, the speed of the PTO output end is reversed accordingly.

[0026] The working method of the tractor transmission system as described above also includes the following contents:

[0027] PTO neutral mode: In this mode, the first synchronizer is in the middle neutral position, and there is no power and speed output at the PTO output. In this way, useless work such as PTO drag power can be minimized, which helps to improve the overall transmission efficiency of the transmission system.

[0028] The beneficial effects of the present invention are as follows:

[0029] 1) In the present invention, according to the above working method, the speed of the PTO output end can be selectively related to the engine speed or the output vehicle speed, which is suitable for both working conditions with stable PTO speed such as rotary tillage and ground speed PTO working conditions such as sowing, meeting various agronomic needs, improving agricultural results, and increasing the adaptability of the powertrain and tractor working conditions.

[0030] 2) In the first PTO mode of the present invention, part of the engine power is directly output to the PTO shaft through the first shaft, and the other part is output to the front axle and the rear axle through the continuously variable transmission. Due to the continuously variable transmission characteristics of the continuously variable transmission, there is no fixed transmission ratio relationship between the tractor speed and the engine speed. When working in this mode, the vehicle speed changes in real time with the load size, while the engine speed is relatively stable, and thus the PTO output speed is relatively stable, which is suitable for agricultural conditions such as rotary tillage and harrowing.

[0031] 3) In the ground speed PTO mode of the present invention, part of the engine power is output to the PTO shaft through the first synchronizer, and the other part is output to the front axle and the rear axle through the second synchronizer. At this time, the speed of the PTO output end is positively correlated with the vehicle speed, that is, the PTO speed changes in real time with the vehicle speed, which is suitable for agricultural conditions such as sowing and spraying.

[0032] 4) In the present invention, in the PTO reverse mode, the reverse speed generated by the continuously variable transmission is output to the PTO shaft via the second shaft-first synchronizer, thereby realizing the reverse rotation of the PTO shaft, which is suitable for working conditions such as reverse rotation of agricultural machinery to clear weeds.

[0033] 5) In the PTO neutral mode, no power and speed are transmitted to the PTO, which can minimize the useless work such as PTO towing power and PTO oil stirring, and help improve the overall transmission efficiency of the transmission system.

[0034] 6) In the present invention, a third synchronizer is arranged through the fifth shaft, and both sides of the third synchronizer can be respectively combined with corresponding gear transmission parts, so that the PTO output end can have outputs with different speeds. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0036] Figure 1 A schematic diagram of a tractor transmission system according to one or more embodiments of the present invention Figure 1 .

[0037] Figure 2 A schematic diagram of a tractor transmission system according to one or more embodiments of the present invention Figure 2 .

[0038] In the figure: the distances or sizes between parts are exaggerated to show the positions of various parts, and the schematic diagram is for reference only.

[0039] Wherein: S1. first axis, S2. second axis, S3. third axis, S4. fourth axis, S5. fifth axis, S6. sixth axis, S7. seventh axis;

[0040] SY1. The first synchronizer, SY2. The second synchronizer, SY3. The third synchronizer;

[0041] Z1. first gear, Z2. second gear, Z3. third gear, Z4. fourth gear, Z5. fifth gear, Z6. sixth gear, Z7. seventh gear, Z8. eighth gear, Z9. ninth gear, Z10. tenth gear, Z11. eleventh gear, Z12. twelfth gear;

[0042] G1. The first transition gear, G2. The second transition gear, G3. The third transition gear, G4. The fourth transition gear, G5. The fifth transition gear, G6. The sixth transition gear, G7. The seventh transition gear. DETAILED DESCRIPTION

[0043] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0044] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless otherwise explicitly stated in the present invention, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof;

[0045] As introduced in the background technology, the prior art cannot achieve the problem that the rotation speed of the PTO output end is positively correlated with the vehicle speed. In order to solve the above technical problem, the present invention proposes a transmission system for a tractor.

[0046] Embodiment 1

[0047] In a typical embodiment of the present invention, reference is made to Figure 1As shown, a transmission system for a tractor comprises a first shaft S1 and a second shaft S2, the first shaft is directly connected to an engine, the second shaft S2 is an output shaft of a continuously variable transmission, a first synchronizer SY1 is arranged at the output end of the first shaft, the first synchronizer is fixedly connected to the third shaft S3, a second synchronizer SY2 is arranged at the output end of the second shaft, the second synchronizer is fixedly connected to the fourth shaft S4, a first gear pair is arranged between the second shaft and the third shaft, a first gear Z1 in the first gear pair is sleeved on the third shaft and is rotatable relative to the third shaft, a second gear Z2 in the first gear pair is fixedly connected to the second shaft S2, a second gear pair is arranged between the third shaft and the fourth shaft, a fourth gear Z4 in the second gear pair is sleeved on the fourth shaft and is rotatable relative to the fourth shaft, a third gear Z3 in the second gear pair is fixedly connected to the first gear and is rotatable relative to the third shaft, the first synchronizer SY1 can be respectively combined with the first shaft S1 or the first gear Z1 or kept in neutral, the second synchronizer SY2 can be respectively combined with the second gear Z2 or the fourth gear Z4 or kept in neutral, and the fourth shaft is respectively connected to a rear axle structure and a front axle structure;

[0048] A PTO clutch CPTO is provided at the output end of the third shaft, the PTO clutch is connected to the fifth shaft S5, and the output end of the fifth shaft is connected to the PTO output end through a transmission component.

[0049] It needs to be explained that the third shaft supports the first gear and the third gear respectively through the first rotating bearing, so that the first gear and the third gear can rotate synchronously relative to the third shaft; the first transition gear is fixedly connected to the first gear through the first rotating bearing, the first transition gear is located on one side of the first synchronizer, and the first synchronizer can be combined with the first transition gear. When the first synchronizer is combined with the first transition gear, the first synchronizer and the first gear can be combined.

[0050] Moreover, the fourth shaft supports the fourth gear Z4 through the second rotating bearing to ensure that the fourth gear can rotate relative to the fourth shaft. The fourth transition gear is fixedly connected to the fourth gear. The fourth transition gear is located on one side of the second synchronizer. The second synchronizer can be combined with the fourth transition gear to realize the combination of the second synchronizer and the fourth gear; and the third transition gear G3 is set at the output end of the first shaft, and the first synchronizer is combined with the first shaft through the third transition gear. The second transition gear G2 is set at the output end of the second shaft, and the second synchronizer is combined with the second shaft through the second transition gear.

[0051] It is easy to understand that the output end of the fourth shaft is connected to the rear axle structure on the one hand; on the other hand, the fourth shaft is connected to the front axle structure through the transmission assembly;

[0052] The transmission assembly includes a fifth gear Z5 fixed to the fourth shaft, the fifth gear is located on one side of the fourth gear, the fifth gear is meshed with the sixth gear Z6, and the sixth gear is connected to the front axle structure through the sixth shaft S6; of course, in other examples, the fourth shaft can also be connected to the front axle structure through other transmission assemblies.

[0053] In order to realize that the PTO output end has multiple gears, the third synchronizer SY3 is set on the fifth shaft, and the seventh gear Z7 is set on the fifth shaft on one side of the third synchronizer. The seventh gear is rotatable relative to the fifth shaft S5, and the seventh gear Z7 is meshed with the eighth gear Z8, and the eighth gear Z8 is connected to the PTO output end; the ninth gear Z9 is set on the other side of the third synchronizer of the fifth shaft, and the ninth gear is rotatable relative to the fifth shaft, and the ninth gear is meshed with the tenth gear Z10, and the tenth gear is connected to the PTO output end.

[0054] Specifically, the fifth shaft supports the seventh gear and the fifth transition gear through the third rotating bearing, and the third synchronizer can be combined with the fifth transition gear G5 to achieve combination with the seventh gear; the fifth shaft supports the ninth gear and the sixth transition gear G6 through the fourth rotating bearing, and the third synchronizer can be combined with the sixth transition gear to achieve combination with the ninth gear; in addition, the eighth gear and the tenth gear are fixed to the seventh shaft S7, and the output end of the seventh shaft is the PTO output end.

[0055] It should be noted that the first rotary bearing, the second rotary bearing, the third rotary bearing and the fourth rotary bearing are respectively existing rolling bearings, and of course, they may also be other structural parts.

[0056] Among them, the continuously variable transmission, the first synchronizer, the second synchronizer, the third synchronizer, and the PTO clutch are all existing structural parts.

[0057] It can be understood that the second synchronizer has multiple gears, which means that the second synchronizer is combined with the second gear on one side in high gear and with the fourth gear on the other side in low gear; the third synchronizer also has multiple gears, and the third synchronizer can be combined with the seventh gear on one side, or with the ninth gear on the other side.

[0058] In other examples, in order to achieve the third gear position at the PTO output end, refer to Figure 2 As shown, the fourth synchronizer SY4 can be set at the seventh shaft S7, specifically, the eleventh gear Z11 is set on the fifth shaft, the eleventh gear is meshed with the twelfth gear, the seventh shaft supports the seventh transition gear and the twelfth gear through a rotating bearing, the fourth synchronizer is fixedly connected to the seventh shaft, and the fourth synchronizer can be combined with the seventh transition gear, so as to achieve the output of different PTO output end transmission ratios.

[0059] The transmission system provided in this embodiment can realize the PTO output end speed that can be selectively related to the engine speed or the output vehicle speed as a whole, meet the ground speed PTO working condition requirements and agronomic requirements of tractor sowing, improve agricultural results, and increase the working condition adaptability of the powertrain and tractor.

[0060] Embodiment 2

[0061] This embodiment discloses a working method of a tractor transmission system, including the following contents:

[0062] The first PTO mode is the traditional PTO mode: in this mode, the first synchronizer SY1 is combined with the first shaft S1. At this time, part of the engine input power is transmitted to the second shaft SY2 through the continuously variable transmission, and the second synchronizer can select high and low gears. When the second synchronizer is in low gear, it is directly combined with the second shaft S2, and part of the engine input power is directly transmitted to the front axle structure and the rear axle structure through the second shaft S2-second synchronizer SY2-fourth shaft S4. When the second synchronizer is in high gear, the second synchronizer is combined with the fourth gear, and part of the engine input power is transmitted to the front axle structure and the rear axle structure by the second shaft S2-first gear pair Z2-Z1-second gear pair Z3-Z4-second synchronizer SY2-fourth shaft S4.

[0063] In the first PTO mode, the other part of the engine power and speed is transmitted to the PTO clutch CPTO and the third synchronizer SY3 through the first synchronizer SY1 and the third shaft. The third synchronizer SY3 can select different PTO gears and transmit to the PTO output end through the third synchronizer SY3-seventh gear Z7-eighth gear Z8 or through the third synchronizer SY3-ninth gear Z9-tenth gear Z10. In this mode, the speed of the PTO output end is positively correlated with the engine speed and has nothing to do with the vehicle speed (the front and rear axle speeds determine the vehicle speed).

[0064] Ground speed PTO mode (in this mode, the speed of the PTO output end is positively correlated with the running speed of the tractor): In this mode, the first synchronizer SY1 is combined with the first gear Z1. At this time, the engine input power is transmitted to the second synchronizer SY2 through the continuously variable transmission. The second synchronizer can select high and low gears. When the second synchronizer is in low gear, it is directly combined with the second shaft S2. A part of the engine input power is directly transmitted to the front and rear axle structures through the second shaft S2-second synchronizer SY2-fourth shaft S4; the other part of the engine input power and speed is transmitted to the third synchronizer SY3 via the second gear Z2-first gear Z1-first synchronizer SY1-third shaft S3-PTO clutch CPTO;

[0065] The second synchronizer SY2 is combined with the fourth gear Z4 in high gear, and part of the engine input power is transmitted to the front axle and rear axle structure via the second shaft S2-first gear pair Z2-Z1-second gear pair Z3-Z4-second synchronizer SY2-fourth shaft S4, and the other part of the engine input power is transmitted to the third synchronizer SY3 via the second shaft S2-first gear pair Z2-Z1-first synchronizer SY1-third shaft S3-PTO clutch.

[0066] The third synchronizer SY3 can select different PTO gears, and transmit to PTO output through the third synchronizer SY3-seventh gear Z7-eighth gear Z8 or transmit to PTO output through the third synchronizer SY3-ninth gear Z9-tenth gear Z10. In this mode, the PTO speed has nothing to do with the engine speed, but is related to the vehicle speed (front and rear axle speed). The transmission ratio can be calculated by the gear ratio, which will not be repeated here.

[0067] PTO reverse mode: In the above ground speed PTO mode, the second shaft S2 is in reverse gear through the continuously variable transmission (because the second shaft is the output shaft of the continuously variable transmission), and at the same time, the second synchronizer SY2 is in the middle neutral position, the first synchronizer SY1 is combined with the first gear Z1, and the engine input power and speed are transmitted to the third synchronizer SY3 through the second shaft S2-second gear Z2-first gear Z1-first synchronizer SY1-third shaft S3-PTO clutch CPTO, and the PTO output end rotates in the opposite direction. In this mode, the PTO output end is reversed, which can be used for special working conditions such as reversing agricultural implements. For example, a baler can remove stuck weeds by reversing.

[0068] PTO neutral mode: In this mode, the first synchronizer SY1 is in the middle neutral position, and the PTO has no power and speed output. In this mode, useless work such as PTO drag power can be minimized, which helps to improve the overall transmission efficiency of the transmission system.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A transmission system for a tractor, characterized in that: The invention comprises a first shaft and a second shaft, wherein the first shaft is directly connected to the engine, the second shaft is the output shaft of the continuously variable transmission, a first synchronizer is arranged at the output end of the first shaft, the first synchronizer is fixedly connected to the third shaft, a second synchronizer is arranged at the output end of the second shaft, the second synchronizer is fixedly connected to the fourth shaft, a first gear pair is arranged between the second shaft and the third shaft, a first gear in the first gear pair is sleeved on the third shaft and is rotatable relative to the third shaft, a second gear in the first gear pair is fixedly connected to the second shaft, a second gear pair is arranged between the fourth shaft and the third shaft, the third gear in the second gear pair is sleeved on the third shaft and is rotatable relative to the third shaft, the first gear and the third gear can rotate synchronously, the fourth gear in the second gear pair is sleeved on the fourth shaft and is rotatable relative to the fourth shaft, the first synchronizer can be respectively combined with the first shaft or the first gear or kept in neutral, and the second synchronizer can be respectively combined with the second gear or the fourth gear or kept in neutral; A PTO clutch is arranged at the output end of the third shaft, the PTO clutch is connected to the fifth shaft, and the output end of the fifth shaft is connected to the PTO output end through a transmission component.

2. A tractor transmission system according to claim 1, characterized in that: The third shaft supports the first gear and the third gear respectively through a first rotating bearing; The fourth shaft supports the fourth gear via a second rotary bearing.

3. A tractor transmission system according to claim 2, characterized in that: The third shaft also supports a first transition gear through the first rotary bearing, the first transition gear is located on one side of the first synchronizer, and the first synchronizer can be combined with the first transition gear; The fourth shaft also supports a fourth transition gear through the second rotary bearing. The fourth transition gear is located on one side of the second synchronizer. The second synchronizer can be combined with the fourth transition gear.

4. A tractor transmission system according to claim 1, characterized in that: The output end of the fourth shaft is connected to the rear axle structure, and the fourth shaft is connected to the front axle structure through a transmission assembly; The transmission assembly includes a fifth gear fixed to the fourth shaft, the fifth gear is located on one side of the fourth gear, the fifth gear is meshed with the sixth gear, and the sixth gear is connected to the front axle structure through the sixth shaft.

5. A transmission system for a tractor according to claim 1, characterized in that: The fifth shaft is provided with a third synchronizer, the third synchronizer is fixedly connected to the fifth shaft, the fifth shaft is located on one side of the third synchronizer and a seventh gear is provided, the seventh gear rotates synchronously with the fifth transition gear, the seventh gear is rotatable relative to the fifth shaft, the seventh gear is meshed with the eighth gear, and the eighth gear is connected to the PTO output end through the seventh shaft; The fifth shaft is located on the other side of the third synchronizer and a ninth gear is set. The ninth gear rotates synchronously with the sixth transition gear and is rotatable relative to the fifth shaft. The ninth gear is meshed with the tenth gear, and the tenth gear is connected to the PTO output end through the seventh shaft.

6. A method for operating a tractor transmission system according to any one of claims 1 to 5, characterized in that: It includes the following: First PTO mode: In this mode, the first synchronizer is combined with the first shaft. At this time, a part of the engine input power is transmitted to the second shaft through the continuously variable transmission. The second synchronizer can select high and low gears. When the second synchronizer is in low gear, it is directly combined with the second shaft, and a part of the engine input power is directly transmitted to the front axle structure and the rear axle structure through the second shaft-second synchronizer-fourth shaft. When the second synchronizer is in high gear, the second synchronizer is combined with the fourth gear, and a part of the engine input power is transmitted to the front axle structure and the rear axle structure by the second shaft-first gear pair-second gear pair-second synchronizer-fourth shaft.

7. A method for operating a tractor transmission system according to claim 6, characterized in that: In the first PTO mode, another part of the engine power and speed is transmitted to the PTO clutch and the third synchronizer via the first synchronizer and the third shaft. The third synchronizer can select different PTO gears and transmit it to the PTO output end through the third synchronizer-seventh gear-eighth gear or through the third synchronizer-ninth gear-tenth gear.

8. The operating method of a tractor transmission system according to claim 6, characterized in that: Also includes the following: Ground speed PTO mode: The first synchronizer is combined with the first gear. At this time, the engine input power is transmitted to the second synchronizer through the continuously variable transmission. The second synchronizer can select high and low gears. When the second synchronizer is in low gear, it is directly combined with the second shaft. A part of the engine input power is directly transmitted to the front and rear axle structures through the second shaft-second synchronizer-fourth shaft; the other part of the engine input power and speed are transmitted to the output end via the first gear pair-first synchronizer-third shaft-PTO clutch; The second synchronizer is combined with the fourth gear in high gear, and part of the engine input power is transmitted to the front axle and rear axle structure via the second shaft-first gear pair-second gear pair-second synchronizer-fourth shaft, and the other part of the engine input power is transmitted to the PTO output end via the second shaft-first gear pair-first synchronizer-third shaft-PTO clutch.

9. A method for operating a tractor transmission system according to claim 8, characterized in that: Also includes the following: PTO reverse mode: The second shaft is in reverse gear through the continuously variable transmission. At the same time, the second synchronizer is in the middle neutral position, the first synchronizer is combined with the first gear, and the engine input power and speed are transmitted to the PTO output end through the second shaft-first gear pair-first synchronizer-third shaft-PTO clutch. At this time, the speed of the PTO output end is reversed accordingly.

10. The operating method of a tractor transmission system according to claim 6, characterized in that: Also includes the following: PTO neutral mode: In this mode, the first synchronizer is in the middle neutral position, and there is no power and speed output at the PTO output.

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