Quick brake clutch assembly and its reduction gearbox

Abstract

The application discloses a quick brake clutch assembly and a reduction gearbox thereof, and relates to the technical field of tractor reduction gearboxes. The clutch assembly comprises a reduction gearbox shell, an input shaft and an output shaft arranged in the reduction gearbox shell, a gear shaft sleeve, a clutch hub, a driving piston and a brake mechanism. The application also provides a reduction gearbox comprising the quick brake clutch assembly, and the reduction gearbox shell has a transmission chamber and an oil storage chamber which are communicated. The reduction gearbox further comprises a gear pump and a control valve body. The quick brake clutch assembly provided by the application is driven by oil pressure, so that the driving piston is actuated to press the main friction plate and the driven steel sheet, the gear shaft sleeve and the clutch hub are relatively fixed, and then the input shaft can drive the output shaft to actuate. When the pressure is released and separated, the driving piston is driven by the spring to press the fixed brake plate and the rotating brake plate, so that the output shaft can be quickly stopped, and the effect of quick braking is achieved.

Description

Technical Field

[0001] This invention relates to the field of tractor gearbox technology, and more specifically to a fast braking clutch assembly and its gearbox. Background Technology

[0002] A tractor is a self-propelled power unit used to tow and drive work machinery to complete various mobile tasks, and can also be used for stationary work. It consists of an engine, transmission, running gear, steering, hydraulic suspension, power output, electrical instruments, driving controls, and traction systems or devices. Engine power is transmitted to the drive wheels through the transmission system, enabling the tractor to move. In real life, rubber belts are commonly used as the power transmission medium. Tractors are classified by function and purpose into agricultural, industrial, and special-purpose tractors; and by structural type into wheeled, tracked, boat-shaped tractors, and self-propelled chassis tractors.

[0003] Most of the gearboxes currently used in tractors employ wet clutches for gear shifting. During gear shifting, the fluid flowing to the clutch is controlled by a shift valve to engage or disengage the clutch.

[0004] However, due to the way the hydraulic pressure is controlled, braking cannot be performed quickly when the clutch is disengaged. The hydraulic pressure needs to gradually decrease after braking, and the rotating structure cannot stop quickly, which limits the braking effect.

[0005] Therefore, how to provide a fast braking clutch assembly and its reduction gearbox suitable for tractors is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a fast braking clutch assembly and its reduction gearbox, aiming to solve the above-mentioned technical problems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A quick-closing clutch assembly includes a gearbox housing, wherein an input shaft and an output shaft are disposed inside the gearbox housing, and the input shaft and the output shaft are rotatably connected inside the gearbox housing via bearings; further comprising:

[0009] A gear bushing is rotatably connected to the outside of the output shaft via a bearing. Both the gear bushing and the outside of the input shaft are fitted with meshing gear sets. Multiple main friction plates are fixedly fitted at intervals on the outer wall of the gear bushing.

[0010] The clutch hub is fixedly sleeved on the output shaft and located outside the plurality of main friction plates; the inner ring cavity sidewall of the clutch hub is fixed with a plurality of driven steel plates at intervals, and the plurality of driven steel plates are interleaved with the plurality of main friction plates; the central hole of the clutch hub has a first channel communicating with the inner ring cavity of the clutch hub.

[0011] A drive piston is slidably connected to the inner ring cavity of the clutch hub. A spring is provided between the drive piston and the end face of the clutch hub. After the oil enters the inner ring cavity through the first channel, it can push the drive piston to move and overcome the elastic force of the spring to press the main friction plate and the driven steel plate. A brake pin facing away from the driven steel plate is fixed on the edge of the drive piston.

[0012] The braking mechanism includes a fixed brake pad and a rotating brake pad. The fixed brake pad is fixed to the inner wall of the gearbox housing and is arranged coaxially with the output shaft. There are multiple rotating brake pads, which are fixed to the edge of the clutch hub and clamped on both sides of the fixed brake pad. The rotating brake pads correspond to the brake pin.

[0013] Through the above technical solution, the fast braking clutch assembly provided by the present invention, under the push of hydraulic force, causes the drive piston to move, presses the main friction plate and the driven steel plate, and fixes the gear bushing and the clutch hub, thereby enabling the input shaft to drive the output shaft to move. When the pressure is released and the clutch is disengaged, the drive piston, under the action of the spring, causes the brake pin to press the fixed brake plate and the rotating brake plate, so that the output shaft can stop rotating quickly, achieving the effect of fast braking.

[0014] Preferably, in the above-mentioned fast braking clutch assembly, both the input shaft and the output shaft are rotatably connected inside the gearbox housing via deep groove ball bearings and cylindrical roller bearings; the gear bushing is rotatably connected to the outside of the output shaft via a deep groove ball bearing. This ensures the rotational performance of the input shaft, output shaft, and gear bushing.

[0015] Preferably, in the above-described quick-brake clutch assembly, the drive piston has a spring limiting groove, and the spring portion is placed within the spring limiting groove. The spring limiting groove can restrict the position of the spring, ensuring the stability of its operation.

[0016] The present invention also provides a gearbox, including the above-mentioned fast braking clutch assembly, wherein the gearbox housing has a communicating transmission chamber and an oil reservoir; and further includes: a gear pump and a control valve body;

[0017] The power input end of the gear pump is connected to the end of the input shaft, and the oil suction port of the gear pump is connected to the oil storage chamber through a first external pipeline;

[0018] The control valve body is fixed to the outer wall of the gearbox housing. The control valve body has an internal control oil passage. The inlet of the control oil passage is connected to the pump port of the gear pump via a second external pipeline. An elastic pressure valve is installed inside the control oil passage. A return oil passage is formed on the control oil passage between the elastic pressure valve and the inlet of the control oil passage. The end of the return oil passage is divided into a power oil passage and a primary pressure relief oil passage. The power oil passage connects to the transmission chamber and is used to drive the clutch assembly. The primary pressure relief oil passage connects to the inlet of an elastic piston valve fixed to the outer wall of the gearbox housing. The outlet of the elastic piston valve connects to the oil reservoir via a third external pipeline. A secondary pressure relief oil passage is formed on the control oil passage on the closed side of the elastic pressure valve. The secondary pressure relief oil passage connects to the transmission chamber and provides splash lubrication. The opening pressure of the elastic pressure valve is greater than the opening pressure of the elastic piston valve.

[0019] Through the above technical solution, the gearbox provided by the present invention uses an oil system to control the operation of the clutch assembly. After the oil is drawn in by the gear pump, it is pumped into the operating oil passage through the second external pipeline, and then enters the power oil passage through the return oil passage to drive the clutch assembly. When the oil pressure gradually increases, the elastic piston valve is pushed open and started. The oil flows back to the oil reservoir through the outlet of the elastic piston valve through the third external pipeline to relieve pressure. When the oil pressure increases again, the oil pressure pushes the elastic pressure valve, and the oil enters the transmission chamber through the secondary pressure relief oil passage. After splash lubrication, it falls back into the oil reservoir. The present invention controls the oil pressure within a stable range by controlling the opening and closing of each valve body of the operating valve body, ensuring stable system pressure, and improving the service life and control accuracy of the gearbox.

[0020] Preferably, in the aforementioned gearbox, the output shaft has a first shaft flow channel and a second shaft flow channel inside its shaft body. One end of the first shaft flow channel is connected to the power oil passage, and the other end is connected to the transmission chamber used to drive the clutch assembly. One end of the second shaft flow channel is connected to the secondary pressure relief oil passage, and the other end is connected to the transmission chamber used for splash lubrication. A second channel is also provided on the center hole of the clutch hub. The first channel is located on the boosting drive side of the drive piston, and the second channel is located on the pressure relief side of the drive piston. The opening and arrangement of each flow channel allows oil to flow between the components. By controlling the movement of the drive piston, frictional engagement between the friction plates can be achieved.

[0021] Preferably, in the aforementioned gearbox, the elastic piston valve includes an elastic piston valve housing fixed to the outer wall of the gearbox housing. An elastic piston is slidably connected inside the elastic piston valve housing, and one end of the elastic piston is pressed against the inside of the elastic piston valve housing by a compression spring, thereby disconnecting the passage between the primary pressure relief oil passage and the third external pipeline. The action control of the elastic piston under a specific oil pressure is achieved using the elastic force of the compression spring, resulting in a simple structure and high stability.

[0022] Preferably, in the aforementioned gearbox, the elastic pressure valve includes a push rod sleeve slidably connected within the control oil passage. A push rod is coaxially slidably connected to the inner side of the push rod sleeve. A push rod spring is slidably sleeved on the push rod, and the push rod spring presses against the top of the push rod and the push rod sleeve. A steel ball is fixed to the top of the push rod, and the steel ball, under the action of the push rod spring, blocks the oil inlet of the control oil passage. The spring force of the push rod spring is used to control the movement of the push rod under a specific oil pressure, resulting in a simple structure and high stability.

[0023] Preferably, in the aforementioned gearbox, a manual brake valve is connected to the bottom of the push rod sleeve; the side wall of the control valve body has a valve hole radially opened, corresponding to the bottom of the push rod sleeve, and a brake valve shaft is rotatably connected within the valve hole. A valve stem is radially fixed to one end of the brake valve shaft extending outside the control valve body, and an eccentric pin is fixed to the other end of the brake valve shaft. A sliding groove is radially opened at the bottom of the push rod sleeve, and the eccentric pin is inserted into the sliding groove. To improve control performance, this invention utilizes a manual brake valve to quickly release oil pressure, enabling rapid braking.

[0024] Preferably, in the aforementioned gearbox, the end of the input shaft furthest from the gear pump extends through the gearbox housing and has a flange at that end; the output shaft has a power output end extending through the gearbox housing. This satisfies the connection requirements between the power input component and the power output component.

[0025] Preferably, in the aforementioned gearbox, a filter is installed at the outlet where the oil storage chamber connects to the first external pipeline. Adding a filter ensures the cleanliness of the circulating oil.

[0026] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a fast braking clutch assembly and its reduction gearbox, which has the following beneficial effects:

[0027] 1. The fast braking clutch assembly provided by the present invention, under the push of hydraulic pressure, causes the drive piston to move, pressing the main friction plate and the driven steel plate, thereby fixing the gear bushing and the clutch hub, and thus enabling the input shaft to drive the output shaft to move. When the pressure is released and the clutch is disengaged, the drive piston, under the action of the spring, causes the brake pin to press the fixed brake plate and the rotating brake plate, so that the output shaft can stop rotating quickly, achieving the effect of fast braking.

[0028] 2. The gearbox provided by this invention uses an oil system to control the clutch assembly. After the oil is drawn in by the gear pump, it is pumped into the operating oil passage through the second external pipeline, and then enters the power oil passage through the return oil passage to drive the clutch assembly. When the oil pressure gradually increases, the elastic piston valve is pushed open and started. The oil flows back to the oil reservoir through the outlet of the elastic piston valve through the third external pipeline to relieve pressure. When the oil pressure increases again, the oil pressure pushes the elastic pressure valve, and the oil enters the transmission chamber through the secondary pressure relief oil passage. After splash lubrication, it falls back into the oil reservoir. This invention controls the oil pressure within a stable range by controlling the opening and closing of each valve body of the control valve body, ensuring stable system pressure, and improving the service life and control accuracy of the gearbox.

[0029] 3. In order to improve the control effect, the present invention utilizes a manual brake valve, which can quickly release the pressure of the oil and achieve rapid braking. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0031] Figure 1 The attached figure is an external front view of the gearbox provided by the present invention;

[0032] Figure 2 The attached figure is a partial cross-sectional external rear view of the gearbox provided by the present invention;

[0033] Figure 3 The attached figure is a cross-sectional view of the internal structure of the gearbox provided by the present invention;

[0034] Figure 4 The attached figure is provided by the present invention. Figure 3 A magnified view of part A in the middle;

[0035] Figure 5 The attached figure is a partial cross-sectional view of the elastic piston valve provided by the present invention;

[0036] Figure 6 The attached figure is a partial cross-sectional view of the elastic pressure valve provided by the present invention;

[0037] Figure 7 The attached figure is a schematic diagram of the external structure of the manual brake valve provided by the present invention;

[0038] Figure 8 The attached figure is a schematic diagram of the internal structure of the manual brake valve provided by the present invention;

[0039] Figure 9 The attached figure is a partial structural cross-sectional view of the fast braking clutch assembly provided by the present invention;

[0040] Figure 10 The attached figure is a side view of the fast braking clutch assembly provided by the present invention.

[0041] in:

[0042] 1-Gearbox housing; 2-Gear pump; 3-Transmission chamber; 4-Oil reservoir; 5-Input shaft; 6-Output shaft; 7-Gear set; 8-First external pipeline; 9-Control valve body; 10-Control oil passage; 11-Second external pipeline; 12-Elastic pressure valve; 13-Return oil passage; 14-Power oil passage; 15-First-stage pressure relief oil passage; 16-Clutch assembly; 17-Elastic piston valve; 18-Third external pipeline; 19-Second-stage pressure relief oil passage; 20-First shaft body passage; 21-Second shaft body passage; 22-Clutch hub; 23-First channel; 24-Second channel; 25-Drive piston; 26-Elastic piston valve housing; 27-Elastic piston; 28-Compression spring; 29-Push rod sleeve; 30-Push rod; 31-Push rod spring; 32-Steel ball; 33-Manual brake valve; 34-Valve hole; 35-Brake valve shaft; 36-Valve stem; 37-Eccentric pin; 38-Slide groove; 39-Flange; 40-Power output end; 41-Filter; 42-Gear bushing; 43-Main friction plate; 44-Driven steel plate; 45-Center hole; 46-Inner ring cavity; 47-Spring; 48-Brake pin; 49-Brake mechanism; 50-Fixed brake pad; 51-Rotating brake pad; 52-Spring limit groove. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] See appendix Figure 1 To be continued Figure 10This invention discloses a gearbox, including a gearbox housing 1, an input shaft 5 and an output shaft 6 disposed inside the gearbox housing 1, and the input shaft 5 and the output shaft 6 being rotatably connected inside the gearbox housing 1 via bearings; it also includes:

[0045] Gear bushing 42 is rotatably connected to the outside of output shaft 6 via bearing. Gear sets 7 that mesh with each other are fixedly sleeved on the outside of both gear bushing 42 and input shaft 5. Multiple main friction plates 43 are fixedly sleeved at intervals on the outer wall of gear bushing 42.

[0046] The clutch hub 22 is fixedly sleeved on the output shaft 6 and located outside the multiple main friction plates 43; the inner ring cavity 46 of the clutch hub 22 has multiple driven steel plates 44 fixed at intervals on its side wall, and the multiple driven steel plates 44 are interleaved with the multiple main friction plates 43; the center hole 45 of the clutch hub 22 has a first channel 23 communicating with the inner ring cavity 46 of the clutch hub 22;

[0047] The drive piston 25 is slidably connected in the inner ring cavity 46 of the clutch hub 22. A spring 47 is provided between the drive piston 25 and the end face of the clutch hub 22. After the oil enters the inner ring cavity 46 through the first channel 23, it can push the drive piston 25 to move and overcome the elastic force of the spring 47 to press the main friction plate 43 and the driven steel plate 44. A brake pin 48 facing away from the driven steel plate 44 is fixed on the edge of the drive piston 25.

[0048] Braking mechanism 49 includes fixed brake pad 50 and rotating brake pad 51. Fixed brake pad 50 is fixed to the inner wall of gearbox housing 1 and is arranged coaxially with output shaft 6. There are multiple rotating brake pads 51, which are fixed to the edge of clutch hub 22 and clamped on both sides of fixed brake pad 50. Rotating brake pad 51 corresponds to brake pin 48.

[0049] To further optimize the above technical solution, both the input shaft 5 and the output shaft 6 are rotatably connected inside the gearbox housing 1 via deep groove ball bearings and cylindrical roller bearings; the gear bushing 42 is rotatably connected to the outside of the output shaft 6 via deep groove ball bearings.

[0050] See appendix Figure 9 The drive piston 25 has a spring limiting groove 52, and the spring 47 is partially placed in the spring limiting groove 52.

[0051] The above structure is the basic structure of the gearbox transmission structure and clutch assembly 16 in this embodiment. This embodiment also includes an oil control system:

[0052] See appendix Figure 1 To be continued Figure 6The gearbox housing 1 has a transmission chamber 3 and an oil storage chamber 4 that are connected inside; it also includes a gear pump 2 and a control valve body 9;

[0053] The power input end of the gear pump 2 is connected to the end of the input shaft 5, and the oil suction port of the gear pump 2 is connected to the oil storage chamber 4 through the first external pipeline 8.

[0054] The control valve body 9 is fixed to the outer wall of the gearbox housing 1. The control valve body 9 has an internal control oil passage 10. The oil inlet of the control oil passage 10 is connected to the pump port of the gear pump 2 via a second external pipeline 11. An elastic pressure valve 12 is installed inside the control oil passage 10. A return oil passage 13 is opened on the control oil passage 10 between the elastic pressure valve 12 and the oil inlet. The end of the return oil passage 13 is divided into a power oil passage 14 and a first-stage pressure relief oil passage 15. The power oil passage 14 is connected to the transmission... The chamber 3 is used to drive the clutch assembly 16. The primary pressure relief oil passage 15 is connected to the inlet of the elastic piston valve 17 fixed on the outer wall of the gearbox housing 1. The outlet of the elastic piston valve 17 is connected to the oil reservoir 4 through the third external pipeline 18. The operating oil passage 10 on the closed side of the elastic pressure valve 12 is provided with a secondary pressure relief oil passage 19. The secondary pressure relief oil passage 19 is connected to the transmission chamber 3 and performs splash lubrication. The opening pressure of the elastic pressure valve 12 is greater than the opening pressure of the elastic piston valve 17.

[0055] To further optimize the above technical solution, a first shaft flow channel 20 and a second shaft flow channel 21 are provided inside the shaft body of the output shaft 6. One end of the first shaft flow channel 20 is connected to the power oil passage 14, and the other end is connected to the transmission chamber 3 used to drive the clutch assembly 16. One end of the second shaft flow channel 21 is connected to the secondary pressure relief oil passage 19, and the other end is connected to the transmission chamber 3 used for splash lubrication. A second channel 24 is also provided on the center hole of the clutch hub 22. The first channel 23 is located on the boosting drive side of the drive piston 25, and the second channel 24 is located on the pressure relief side of the drive piston 25.

[0056] See appendix Figure 5 The elastic piston valve 17 includes an elastic piston valve housing 26 fixed to the outer wall of the gearbox housing 1. An elastic piston 27 is slidably connected inside the elastic piston valve housing 26. One end of the elastic piston 27 is pressed against the inside of the elastic piston valve housing 26 by a compression spring 28, so that the elastic piston 27 disconnects the passage between the first-stage pressure relief oil passage 15 and the third external pipeline 18.

[0057] See appendix Figure 6The elastic pressure valve 12 includes a push rod sleeve 29 slidably connected in the control oil passage 10. A push rod 30 is slidably connected coaxially inside the push rod sleeve 29. A push rod spring 31 is slidably sleeved on the push rod 30. The push rod spring 31 is pressed between the top of the push rod 30 and the push rod sleeve 29. A steel ball 32 is fixed at the top of the push rod 30. The steel ball 32 blocks the oil inlet of the control oil passage 10 under the action of the push rod spring 31.

[0058] See appendix Figure 7 and attached Figure 8 The bottom of the push rod sleeve 29 is connected to a manual brake valve 33; the side wall of the control valve body 9 is radially provided with a valve hole 34 corresponding to the bottom of the push rod sleeve 29, a brake valve shaft 35 is rotatably connected in the valve hole 34, a valve stem 36 is radially fixed at one end of the brake valve shaft 35 that protrudes outside the control valve body 9, and an eccentric pin 37 is fixed at the other end of the brake valve shaft 35. The bottom of the push rod sleeve 29 is radially provided with a sliding groove 38, and the eccentric pin 37 is inserted into the sliding groove 38.

[0059] To further optimize the above technical solution, the end of the input shaft 5 away from the gear pump 2 extends out of the gearbox housing 1 and has a flange 39 at the end, and the output shaft 6 has a power output end 40 extending out of the gearbox housing 1.

[0060] To further optimize the above technical solution, a filter 41 is installed at the outlet where the oil storage chamber 4 is connected to the first external pipeline 8.

[0061] The driving principle of this embodiment is as follows:

[0062] The structure of this embodiment mainly consists of three parts: the transmission structure, the clutch, and the hydraulic control. The transmission principle of each part will be explained below:

[0063] Transmission structure: Power is input from the input shaft 5 and transmitted to the gear bushing 42 via the gear set 7. The gear bushing 42 rotates relative to the output shaft 6. At this time, the main friction plate 43 fixed on the gear bushing 42 is in a disengaged state relative to the driven steel plate 44 fixed on the clutch hub 22, and the output shaft 6 does not rotate.

[0064] Clutch section: By driving the piston 25 to press the main friction plate 43 and the driven steel plate 44, the clutch hub 22 and the gear bushing 42 are relatively fixed, thereby driving the output shaft 6 to rotate.

[0065] Hydraulic control section: The input shaft 5 rotates, driving the gear pump 2 to draw in oil. The oil enters the operating oil passage 10 through the second external pipeline 11, and then passes through the return oil passage 13, the power oil passage 14, the first shaft passage 20, and the first channel 23, pushing the drive piston 25 to move, pressing the main friction plate 43 and the driven steel plate 44, achieving relative fixation between the clutch hub 22 and the gear bushing 42, thereby driving the output shaft 6 to rotate. At this time, the internal oil pressure is kept stable between 1.1-1.2 MPa. The oil pressure at this time is insufficient to open the elastic pressure valve 12 and the elastic piston valve 17.

[0066] When the oil pressure continues to rise, and the pressure is greater than 1.2 MPa but less than 1.4 MPa, the oil enters the first-stage pressure relief oil passage 15, pushing the elastic piston 27, causing the oil to flow back from the third external pipeline 18 to the oil storage chamber 4 for pressure relief.

[0067] When the oil pressure continues to rise and exceeds 1.4 MPa, the oil pressure pushes the push rod spring 31, opens the elastic pressure valve 12, and the oil enters the secondary pressure relief oil passage 19. Then, it enters the transmission chamber 3 through the second shaft flow passage 21 and the second channel 24 for splash lubrication, and finally falls back into the oil storage chamber 4.

[0068] When the oil supply is disconnected, the drive piston 25 is pushed back to its original position by the elastic force of the spring 47, and the brake pin 48 presses the fixed brake pad 50 and the rotating brake pad 51 together, which can achieve rapid braking.

[0069] When manual braking is required, pull down the valve stem 36, causing the eccentric pin 37 to drive the push rod sleeve 29 downward, releasing the pressure and allowing the oil to be depressurized, thus enabling manual braking.

[0070] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0071] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A gearbox, characterized in that, The system includes a fast braking clutch assembly, which includes a gearbox housing (1). An input shaft (5) and an output shaft (6) are disposed inside the gearbox housing (1). The input shaft (5) and the output shaft (6) are rotatably connected inside the gearbox housing (1) via bearings. The system also includes: Gear bushing (42), the gear bushing (42) is rotatably connected to the outside of the output shaft (6) by bearing, and gear sets (7) that mesh with each other are fixedly sleeved on the outside of both the gear bushing (42) and the input shaft (5); a plurality of main friction plates (43) are fixedly sleeved at intervals on the outer wall of the gear bushing (42). The clutch hub (22) is fixedly sleeved on the output shaft (6) and located outside the plurality of main friction plates (43); the inner ring cavity (46) of the clutch hub (22) is fixed with a plurality of driven steel plates (44) at intervals, and the plurality of driven steel plates (44) are interleaved with the plurality of main friction plates (43); the center hole (45) of the clutch hub (22) is provided with a first channel (23) communicating with the inner ring cavity (46) of the clutch hub (22). A drive piston (25) is slidably connected in the inner ring cavity (46) of the clutch hub (22). A spring (47) is provided between the drive piston (25) and the end face of the clutch hub (22). After the oil enters the inner ring cavity (46) through the first channel (23), it can push the drive piston (25) to move and overcome the elastic force of the spring (47) to press the main friction plate (43) and the driven steel plate (44). A brake pin (48) facing away from the driven steel plate (44) is fixed on the edge of the drive piston (25). Braking mechanism (49) includes fixed brake pad (50) and rotating brake pad (51). The fixed brake pad (50) is fixed to the inner wall of the gearbox housing (1) and is arranged coaxially with the output shaft (6). There are multiple rotating brake pads (51), which are fixed to the edge of the clutch hub (22) and clamped on both sides of the fixed brake pad (50). The rotating brake pad (51) corresponds to the brake pin (48). The gearbox housing (1) has a connected transmission chamber (3) and an oil storage chamber (4); it also includes a gear pump (2) and a control valve body (9). The power input end of the gear pump (2) is connected to the end of the input shaft (5), and the oil suction port of the gear pump (2) is connected to the oil storage chamber (4) through the first external pipeline (8); The control valve body (9) is fixed on the outer wall of the gearbox housing (1). The control valve body (9) has a control oil passage (10) inside. The oil inlet of the control oil passage (10) is connected to the pump port of the gear pump (2) through a second external pipeline (11). The control oil passage (10) is provided with an elastic pressure valve (12). A return oil passage (13) is opened on the control oil passage (10) between the elastic pressure valve (12) and the oil inlet of the control oil passage (10). The end of the return oil passage (13) is divided into a power oil passage (14) and a first-stage pressure relief oil passage (15). The power oil passage (14) is connected to the gearbox housing (1). The transmission chamber (3) is used to drive the clutch assembly (16) to operate. The first-stage pressure relief oil passage (15) is connected to the inlet of the elastic piston valve (17) fixed on the outer wall of the gearbox housing (1). The outlet of the elastic piston valve (17) is connected to the oil storage chamber (4) through the third external pipeline (18). A second-stage pressure relief oil passage (19) is provided on the operating oil passage (10) on the closed side of the elastic pressure valve (12). The second-stage pressure relief oil passage (19) is connected to the transmission chamber (3) and performs splash lubrication. The opening pressure of the elastic pressure valve (12) is greater than the opening pressure of the elastic piston valve (17).

2. The gearbox according to claim 1, characterized in that, The input shaft (5) and the output shaft (6) are rotatably connected inside the gearbox housing (1) by deep groove ball bearings and cylindrical roller bearings; the gear bushing (42) is rotatably connected outside the output shaft (6) by deep groove ball bearings.

3. A gearbox according to claim 1, characterized in that, The drive piston (25) has a spring limiting groove (52), and the spring (47) is partially placed in the spring limiting groove (52).

4. A gearbox according to claim 1, characterized in that, The output shaft (6) has a first shaft flow channel (20) and a second shaft flow channel (21) inside its shaft body. One end of the first shaft flow channel (20) is connected to the power oil passage (14), and the other end is connected to the transmission chamber (3) used to drive the clutch assembly (16). One end of the second shaft flow channel (21) is connected to the secondary pressure relief oil passage (19), and the other end is connected to the transmission chamber (3) used for splash lubrication. A second channel (24) is also provided on the center hole of the clutch hub (22). The first channel (23) is located on the boosting drive side of the drive piston (25), and the second channel (24) is located on the pressure relief side of the drive piston (25).

5. A gearbox according to claim 1, characterized in that, The elastic piston valve (17) includes an elastic piston valve housing (26) fixed to the outer wall of the gearbox housing (1). An elastic piston (27) is slidably connected inside the elastic piston valve housing (26). One end of the elastic piston (27) is pressed against the inside of the elastic piston valve housing (26) by a compression spring (28), so that the elastic piston (27) disconnects the passage of the first-stage pressure relief oil passage (15) and the third external pipeline (18).

6. A gearbox according to claim 1, characterized in that, The elastic pressure valve (12) includes a push rod sleeve (29) slidably connected in the control oil passage (10). A push rod (30) is slidably connected coaxially inside the push rod sleeve (29). A push rod spring (31) is slidably sleeved on the push rod (30). The push rod spring (31) is pressed between the top of the push rod (30) and the push rod sleeve (29). A steel ball (32) is fixed at the top of the push rod (30). The steel ball (32) blocks the oil inlet of the control oil passage (10) under the action of the push rod spring (31).

7. A gearbox according to claim 6, characterized in that, The bottom of the push rod sleeve (29) is connected to a manual brake valve (33); the side wall of the housing of the control valve body (9) is radially provided with a valve hole (34) corresponding to the bottom of the push rod sleeve (29), a brake valve shaft (35) is rotatably connected in the valve hole (34), a valve rod (36) is radially fixed at one end of the brake valve shaft (35) that protrudes outside the control valve body (9), and an eccentric pin (37) is fixed at the other end of the brake valve shaft (35). The bottom of the push rod sleeve (29) is radially provided with a sliding groove (38), and the eccentric pin (37) is inserted into the sliding groove (38).

8. A gearbox according to claim 1, characterized in that, The input shaft (5) extends out of the gearbox housing (1) at one end away from the gear pump (2) and has a flange (39) at the end. The output shaft (6) has a power output end (40) extending out of the gearbox housing (1).

9. A gearbox according to claim 1, characterized in that, A filter (41) is installed at the outlet of the oil storage chamber (4) connected to the first external pipeline (8).

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