A tractor braking system and method

Abstract

The application provides a tractor braking system and method. A tractor braking system comprises a brake pump, a service brake primary electric proportional valve, a service brake secondary electric proportional valve for connecting with a service brake, a parking brake electric proportional valve for connecting with a parking brake, and an oil tank, the brake pump is connected with the service brake primary electric proportional valve, the service brake secondary electric proportional valve and the parking brake electric proportional valve through pipelines, the service brake secondary electric proportional valve is connected with the service brake primary electric proportional valve through a pipeline, and the service brake primary electric proportional valve and the parking brake electric proportional valve are connected with the oil tank.

Description

Technical Field

[0001] This invention relates to vehicle braking systems, and more particularly to a tractor braking system and method. Background Technology

[0002] With technological advancements, the market demands increasingly higher levels of comfort, reliability, and maintainability from tractors. Currently, tractor braking systems primarily consist of three types: brake cylinders, booster pumps, and pressure-reducing valves. While electronic braking is gradually being adopted in tractors, the increasing demands for improved tractor handling necessitate upgrades and replacements of braking performance. Traditional braking systems offer lower comfort levels and are difficult to maintain. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a tractor braking system and method to address the shortcomings of the prior art.

[0004] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A tractor braking system includes: a brake pump, a primary electro-proportional valve for service brake, a secondary electro-proportional valve for service brake connected to the service brake, a parking brake electro-proportional valve for parking brake connected to the parking brake, and an oil tank. The primary electro-proportional valve for service brake, the secondary electro-proportional valve for service brake, and the parking brake electro-proportional valve are all two-position three-way valves, each including a first oil inlet, a second oil inlet, an oil outlet, and a control oil outlet. The brake pump is connected to the first oil inlet of the primary electro-proportional valve for service brake, the secondary electro-proportional valve for service brake, and the parking brake electro-proportional valve for parking brake via pipelines. The second oil inlet and the control oil outlet of the secondary electro-proportional valve for service brake are both connected to the oil outlet of the primary electro-proportional valve for service brake via pipelines. The second oil inlet of the primary electro-proportional valve for service brake and the second oil inlet of the parking brake electro-proportional valve are both connected to the oil tank.

[0005] The beneficial effects of adopting the technical solution of this invention are: by designing a braking system with a proportional valve group, the comfort of the braking system is increased, and the ease of tractor maintenance is also improved. The control pressure of the primary electro-proportional valve of the service brake serves as the pilot control pressure of the secondary electro-proportional valve of the service brake. This greatly reduces the swivel electromagnetic force of the valve core of the secondary electro-proportional valve of the service brake, thereby reducing the control output pressure pulsation, braking impact, and vibration.

[0006] Furthermore, the oil outlet of the parking brake proportional valve is connected to an emergency valve via a pipeline, and the parking brake proportional valve is connected to the parking brake via the emergency valve.

[0007] The beneficial effect of adopting the above-mentioned further technical solution is that when the tractor fails to start, the emergency valve can be manually closed, and then the brake can be released by pressurizing the external manual pump or the built-in manual pump, which makes it easier to transfer the vehicle for repair.

[0008] Furthermore, the emergency valve is connected to the parking brake via a pipeline, the oil outlet of the emergency valve is connected to the parking brake via a pipeline, a manual pump is connected to the pipeline between the oil outlet of the emergency valve and the parking brake, and the other end of the manual pump is connected to the oil tank via a pipeline.

[0009] The beneficial effect of adopting the above-mentioned further technical solution is that when the tractor fails to start, the emergency valve can be manually closed, and then the brake can be released by manually pressing the pump, which facilitates the transfer of the vehicle for repair.

[0010] Furthermore, a first check valve is connected to the pipeline between the first-stage electro-proportional valve of the service brake and the oil tank, and the first check valve is connected to a safety pressure regulating valve through a pipeline.

[0011] The beneficial effects of adopting the above-mentioned further technical solutions are: the one-way valve prevents the oil from flowing backward, and the safety pressure regulating valve is used to regulate the oil pressure, thereby improving the stability and reliability of the system.

[0012] Furthermore, the secondary electro-proportional valve of the service brake is connected to the service brake via a pipeline.

[0013] The beneficial effects of adopting the above-mentioned further technical solution are: it facilitates the control of the service brake by controlling the control pressure of the secondary electro-proportional valve. The control pressure of the primary electro-proportional valve of the service brake serves as the pilot control pressure of the secondary electro-proportional valve of the service brake, which greatly reduces the swivel electromagnetic force of the valve core of the secondary electro-proportional valve of the service brake, thereby reducing the control output pressure pulsation, braking impact, and vibration.

[0014] Furthermore, the brake pump is connected to a second check valve via a pipeline, the second check valve is connected to a filter via a pipeline, and the filter is connected to the service brake primary electro-proportional valve, the service brake secondary electro-proportional valve, and the parking brake electro-proportional valve via pipelines respectively; an accumulator is installed on the pipeline between the second check valve and the filter.

[0015] The beneficial effects of adopting the above-mentioned further technical solutions are: the check valve is used to prevent oil from flowing backward, the filter is used to filter impurities in the system, and the accumulator is used to store energy, thereby improving the stability and reliability of the system.

[0016] Furthermore, the service brake primary electro-proportional valve, the service brake secondary electro-proportional valve, and the parking brake electro-proportional valve are all connected to a controller, and the controller is connected to a first angle sensor for connection with the pedal and a second angle sensor for connection with the handbrake.

[0017] The beneficial effects of adopting the above-mentioned further technical solution are as follows: the system adapts to electronic pedals, eliminating the need for traditional brake cylinders, booster brake pumps, and pressure reducing valves. Only one pedal is required, equipped with a first angle sensor. When the driver depresses the brake pedal, the angle of the pedal press controls the proportional valve of the service brake, thereby controlling the service brake pressure. The proportional valve can control the output of the desired proportional pressure curve, achieving a more perfect adaptation to the vehicle's braking. A second angle sensor is installed on the tractor's handbrake. When the handbrake is used, it can also output a proportionally controlled pressure curve, effectively matching the vehicle's braking. The elimination of connecting lines from the pedal to the brake reduces cab noise and avoids resonance between the brake lines and the cab.

[0018] In addition, the present invention also provides a tractor braking method. Based on the tractor braking system described above, the tractor braking method includes: when braking the vehicle, using the control pressure of the primary electro-proportional valve of the vehicle braking system as the pilot control pressure of the secondary electro-proportional valve of the vehicle braking system, and performing vehicle braking through the control pressure of the secondary electro-proportional valve of the vehicle braking system; when braking the parking vehicle, performing parking braking through the control pressure of the electro-proportional valve of the parking vehicle braking system.

[0019] The beneficial effects of adopting the technical solution of this invention are: by designing a braking system with a proportional valve group, the comfort of the braking system is increased, and the ease of tractor maintenance is also improved. The control pressure of the primary electro-proportional valve of the service brake serves as the pilot control pressure of the secondary electro-proportional valve of the service brake. This greatly reduces the swivel electromagnetic force of the valve core of the secondary electro-proportional valve of the service brake, thereby reducing the control output pressure pulsation, braking impact, and vibration.

[0020] Furthermore, the service braking steps include: acquiring the pedal rotation angle via a first angle sensor; controlling the control pressure of the first-stage electro-proportional valve of the service brake via a controller based on the pedal rotation angle; using the control pressure of the first-stage electro-proportional valve of the service brake as the pilot control pressure of the second-stage electro-proportional valve of the service brake, and applying the service brake via the control pressure of the second-stage electro-proportional valve of the service brake; the parking braking steps include: acquiring the handbrake rotation angle via a second angle sensor; controlling the control pressure of the parking brake electro-proportional valve of the parking brake via a controller based on the handbrake rotation angle; and applying the parking brake via the control pressure of the parking brake electro-proportional valve.

[0021] The beneficial effects of adopting the above-mentioned further technical solution are as follows: the system adapts to electronic pedals, eliminating the need for traditional brake cylinders, booster brake pumps, and pressure reducing valves. Only one pedal is required, equipped with a first angle sensor. When the driver depresses the brake pedal, the angle of the pedal press controls the proportional valve of the service brake, thereby controlling the service brake pressure. The proportional valve can control the output of the desired proportional pressure curve, achieving a more perfect adaptation to the vehicle's braking. A second angle sensor is installed on the tractor's handbrake. When the handbrake is used, it can also output a proportionally controlled pressure curve, effectively matching the vehicle's braking. The elimination of connecting lines from the pedal to the brake reduces cab noise and avoids resonance between the brake lines and the cab.

[0022] Furthermore, the parking brake procedure includes: when the tractor malfunctions and cannot start, closing the emergency valve and releasing the brake by manually pressurizing the pump.

[0023] The beneficial effect of adopting the above-mentioned further technical solution is that when the tractor fails to start, the emergency valve can be manually closed, and then the brake can be released by manually pressing the pump, which facilitates the transfer of the vehicle for repair.

[0024] The advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of a tractor braking system provided in an embodiment of the present invention.

[0027] Explanation of reference numerals: 1. Brake pump; 2. Primary electro-proportional valve for service brake; 3. Service brake; 4. Secondary electro-proportional valve for service brake; 5. Parking brake; 6. Parking brake electro-proportional valve; 7. Fuel tank; 8. Emergency valve; 9. Manual pump; 10. First check valve; 11. Safety pressure regulating valve; 12. Second check valve; 13. Filter; 14. Accumulator. Detailed Implementation

[0028] The principles and features of the present invention are described below with reference to the accompanying drawings. The embodiments described are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0031] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0032] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0033] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" 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. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0034] like Figure 1As shown, this embodiment of the invention provides a tractor braking system, including: a brake pump 1, a service brake primary proportional valve 2, a service brake secondary proportional valve 4 for connection to a service brake 3, a parking brake proportional valve 6 for connection to a parking brake 5, and an oil tank 7. The service brake primary proportional valve 2, the service brake secondary proportional valve 4, and the parking brake proportional valve 6 are all two-position three-way valves, each including a first oil inlet, a second oil inlet, an oil outlet, and a control oil outlet. The brake pump 1 is connected to the first oil inlet of the service brake primary proportional valve 2, the service brake secondary proportional valve 4, and the parking brake proportional valve 6 via pipelines. The second oil inlet and the control oil outlet of the service brake secondary proportional valve 4 are both connected to the oil outlet of the service brake primary proportional valve 2 via pipelines. The second oil inlet of the service brake primary proportional valve 2 and the second oil inlet of the parking brake proportional valve 6 are both connected to the oil tank 7.

[0035] The beneficial effects of adopting the technical solution of this invention are: by designing a braking system with a proportional valve group, the comfort of the braking system is increased, and the ease of tractor maintenance is also improved. The control pressure of the primary electro-proportional valve of the service brake serves as the pilot control pressure of the secondary electro-proportional valve of the service brake. This greatly reduces the swivel electromagnetic force of the valve core of the secondary electro-proportional valve of the service brake, thereby reducing the control output pressure pulsation, braking impact, and vibration.

[0036] The tractor braking system provided in this embodiment of the invention can be a brand-new all-electronic braking system. The electric pedal, combined with a newly designed proportional valve group, not only increases the comfort of the braking system but also increases the ease of maintenance of the tractor.

[0037] like Figure 1 As shown, further, the parking brake proportional valve 6 is connected to an emergency valve 8 via a pipeline, and the parking brake proportional valve 6 is connected to the parking brake 5 via the emergency valve 8.

[0038] The beneficial effect of adopting the above-mentioned further technical solution is that when the tractor fails to start, the emergency valve can be manually closed, and then the brake can be released by pressurizing the external manual pump or the built-in manual pump, which makes it easier to transfer the vehicle for repair.

[0039] like Figure 1 As shown, the emergency valve 8 is further connected to the parking brake 5 via a pipeline, and a manual pump 9 is connected to the pipeline between the emergency valve 8 and the parking brake 5. The manual pump 9 is connected to the oil tank 7 via a pipeline.

[0040] The beneficial effect of adopting the above-mentioned further technical solution is that when the tractor fails to start, the emergency valve can be manually closed, and then the brake can be released by manually pressing the pump, which facilitates the transfer of the vehicle for repair.

[0041] like Figure 1 As shown, further, a first check valve 10 is connected to the pipeline between the service brake primary proportional valve 2 and the oil tank 7, and the first check valve 10 is connected to a safety pressure regulating valve 11 through a pipeline.

[0042] The beneficial effects of adopting the above-mentioned further technical solutions are: the one-way valve prevents the oil from flowing backward, and the safety pressure regulating valve is used to regulate the oil pressure, thereby improving the stability and reliability of the system.

[0043] One end of the safety pressure regulating valve 11 is connected to the pipeline between the filter 13 and the parking brake electro-proportional valve 6, and the other end of the safety pressure regulating valve 11 is located between the filter 13 and the service brake primary electro-proportional valve 2. The other end of the safety pressure regulating valve 11 is connected to the first check valve 10.

[0044] like Figure 1 As shown, the secondary electro-proportional valve 4 of the service brake is further connected to the service brake 3 via a pipeline.

[0045] The beneficial effects of adopting the above-mentioned further technical solution are: it facilitates the control of the service brake by controlling the control pressure of the secondary electro-proportional valve. The control pressure of the primary electro-proportional valve of the service brake serves as the pilot control pressure of the secondary electro-proportional valve of the service brake, which greatly reduces the swivel electromagnetic force of the valve core of the secondary electro-proportional valve of the service brake, thereby reducing the control output pressure pulsation, braking impact, and vibration.

[0046] like Figure 1 As shown, the brake pump 1 is further connected to a second check valve 12 via a pipeline, the second check valve 12 is connected to a filter 13 via a pipeline, and the filter 13 is connected to the service brake primary electro-proportional valve 2, the service brake secondary electro-proportional valve 4, and the parking brake electro-proportional valve 6 via pipelines respectively; an accumulator 14 is installed on the pipeline between the second check valve 12 and the filter 13.

[0047] The beneficial effects of adopting the above-mentioned further technical solutions are: the check valve is used to prevent oil from flowing backward, the filter is used to filter impurities in the system, and the accumulator is used to store energy, thereby improving the stability and reliability of the system.

[0048] like Figure 1As shown, further, the service brake primary electro-proportional valve 2, the service brake secondary electro-proportional valve 4, and the parking brake electro-proportional valve 6 are all connected to a controller, and the controller is connected to a first angle sensor for connection with the pedal and a second angle sensor for connection with the handbrake.

[0049] The beneficial effects of adopting the above-mentioned further technical solution are as follows: the system adapts to electronic pedals, eliminating the need for traditional brake cylinders, booster brake pumps, and pressure reducing valves. Only one pedal is required, equipped with a first angle sensor. When the driver depresses the brake pedal, the angle of the pedal press controls the proportional valve of the service brake, thereby controlling the service brake pressure. The proportional valve can control the output of the desired proportional pressure curve, achieving a more perfect adaptation to the vehicle's braking. A second angle sensor is installed on the tractor's handbrake. When the handbrake is used, it can also output a proportionally controlled pressure curve, effectively matching the vehicle's braking. The elimination of connecting lines from the pedal to the brake reduces cab noise and avoids resonance between the brake lines and the cab.

[0050] This invention provides a tractor braking system, which can be a fully electronic braking system. This system is adapted to an electronic pedal, eliminating the need for traditional brake cylinders, booster pumps, and pressure reducing valves. Only a pedal is needed, equipped with an angle sensor (first angle sensor). When the driver depresses the brake pedal, the angle of the pedal press controls the service brake proportional valve, thereby controlling the service brake pressure. The proportional valve can control the output proportional pressure curve to achieve the desired effect, resulting in a more perfect fit for the vehicle's braking. Furthermore, the service brake proportional valve is designed with two-stage control: the control pressure of the first-stage proportional valve (service brake first-stage electro-proportional valve 2) serves as the pilot control pressure for the second-stage proportional valve (service brake second-stage electro-proportional valve 4). This significantly reduces the swivel electromagnetic force of the second-stage proportional valve (service brake second-stage electro-proportional valve 4), resulting in smaller output pressure pulsations, less braking shock, and less vibration. This invention achieves a synergistic effect, where 1+1>2. The parking brake also utilizes a proportional valve (parking brake electro-proportional valve 6). An angle sensor (second angle sensor) is installed on the tractor's handbrake. When the handbrake is applied, it outputs proportionally controlled pressure curves, achieving the same effect as the tractor's braking. Furthermore, this embodiment of the invention incorporates an emergency valve in the angle sensor. When the tractor malfunctions and cannot start (in severe cases, it cannot start or be powered), the emergency valve can be manually closed, and the brake can be released by manually pumping pressure. This facilitates the transfer of the vehicle for repair. The emergency valve has a positioning function, allowing for manual operation and positioning before the parking brake is released by manually pumping pressure. This makes the brake valve position more flexible and can also be used when the tractor cannot start or be powered. The tractor braking system of this invention eliminates the need for connecting pipes from the driver's pedal (pedal) to the brake, reducing cab noise and preventing resonance between the brake lines and the cab. This significantly increases braking comfort and greatly improves the ease of tractor maintenance.

[0051] In addition, the present invention also provides a tractor braking method. Based on the tractor braking system described above, the tractor braking method includes: when braking the vehicle, using the control pressure of the primary electro-proportional valve of the vehicle braking system as the pilot control pressure of the secondary electro-proportional valve of the vehicle braking system, and performing vehicle braking through the control pressure of the secondary electro-proportional valve of the vehicle braking system; when braking the parking vehicle, performing parking braking through the control pressure of the electro-proportional valve of the parking vehicle braking system.

[0052] The beneficial effects of adopting the technical solution of this invention are: by designing a braking system with a proportional valve group, the comfort of the braking system is increased, and the ease of tractor maintenance is also improved. The control pressure of the primary electro-proportional valve of the service brake serves as the pilot control pressure of the secondary electro-proportional valve of the service brake. This greatly reduces the swivel electromagnetic force of the valve core of the secondary electro-proportional valve of the service brake, thereby reducing the control output pressure pulsation, braking impact, and vibration.

[0053] Furthermore, the service braking steps include: acquiring the pedal rotation angle via a first angle sensor; controlling the control pressure of the first-stage electro-proportional valve of the service brake via a controller based on the pedal rotation angle; using the control pressure of the first-stage electro-proportional valve of the service brake as the pilot control pressure of the second-stage electro-proportional valve of the service brake, and applying the service brake via the control pressure of the second-stage electro-proportional valve of the service brake; the parking braking steps include: acquiring the handbrake rotation angle via a second angle sensor; controlling the control pressure of the parking brake electro-proportional valve of the parking brake via a controller based on the handbrake rotation angle; and applying the parking brake via the control pressure of the parking brake electro-proportional valve.

[0054] The beneficial effects of adopting the above-mentioned further technical solution are as follows: the system adapts to electronic pedals, eliminating the need for traditional brake cylinders, booster brake pumps, and pressure reducing valves. Only one pedal is required, equipped with a first angle sensor. When the driver depresses the brake pedal, the angle of the pedal press controls the proportional valve of the service brake, thereby controlling the service brake pressure. The proportional valve can control the output of the desired proportional pressure curve, achieving a more perfect adaptation to the vehicle's braking. A second angle sensor is installed on the tractor's handbrake. When the handbrake is used, it can also output a proportionally controlled pressure curve, effectively matching the vehicle's braking. The elimination of connecting lines from the pedal to the brake reduces cab noise and avoids resonance between the brake lines and the cab.

[0055] Furthermore, the parking brake procedure includes: when the tractor malfunctions and cannot start, closing the emergency valve and releasing the brake by manually pressurizing the pump.

[0056] The beneficial effect of adopting the above-mentioned further technical solution is that when the tractor fails to start, the emergency valve can be manually closed, and then the brake can be released by manually pressing the pump, which facilitates the transfer of the vehicle for repair.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A tractor braking system, characterized in that, include: The system includes a brake pump, a primary electro-proportional valve for the service brake, a secondary electro-proportional valve for the service brake, a secondary electro-proportional valve for the parking brake, and a fuel tank. The primary, secondary, and parking brake electro-proportional valves are all two-position three-way valves, each including a first inlet, a second inlet, an outlet, and a control port. The brake pump is connected via pipelines to the first inlet of each valve. The second inlet and control port of the secondary electro-proportional valve are both connected via pipelines to the outlet of the primary electro-proportional valve. The second inlet of the parking brake proportional valve is connected to the oil tank; the outlet of the service brake secondary proportional valve is connected to the service brake via a pipeline; the outlet of the parking brake proportional valve is connected to an emergency valve via a pipeline, and the parking brake proportional valve is connected to the parking brake via the emergency valve; the outlet of the emergency valve is connected to the parking brake via a pipeline, and a manual pump is connected to the pipeline between the outlet of the emergency valve and the parking brake, the other end of the manual pump being connected to the oil tank via a pipeline; the service brake primary proportional valve, the service brake secondary proportional valve, and the parking brake proportional valve are all connected to a controller, and the controller is connected to a first angle sensor for connection with the pedal and a second angle sensor for connection with the handbrake.

2. A tractor braking system according to claim 1, characterized in that, A first check valve is connected to the pipeline between the first-stage electro-proportional valve of the service brake and the oil tank, and the first check valve is connected to a safety pressure regulating valve through a pipeline.

3. A tractor braking system according to claim 1, characterized in that, The brake pump is connected to a second check valve via a pipeline, and the second check valve is connected to a filter via a pipeline. The filter is connected to the first-stage electro-proportional valve of the service brake, the second-stage electro-proportional valve of the service brake, and the electro-proportional valve of the parking brake via pipelines respectively. An accumulator is installed on the pipeline between the second check valve and the filter.

4. A tractor braking method, characterized in that, Based on any one of claims 1 to 3, a tractor braking method includes: When braking, the control pressure of the first-stage electro-proportional valve of the service brake is used as the pilot control pressure of the second-stage electro-proportional valve of the service brake, and the service brake is applied through the control pressure of the second-stage electro-proportional valve of the service brake. When the parking brake is applied, the parking brake is applied by controlling the pressure through the parking brake proportional valve.

5. A tractor braking method according to claim 4, characterized in that, The steps of vehicle braking include: acquiring the rotation angle of the pedal through a first angle sensor; The controller controls the control pressure of the first-stage electro-proportional valve of the service brake based on the rotation angle of the pedal. The control pressure of the first-stage electro-proportional valve of the service brake is used as the pilot control pressure of the second-stage electro-proportional valve of the service brake, and the service brake is performed through the control pressure of the second-stage electro-proportional valve of the service brake. The steps for applying the parking brake include: The rotation angle of the handbrake is acquired by a second angle sensor; The controller controls the control pressure of the parking brake proportional valve based on the rotation angle of the handbrake. The parking brake is applied by controlling the pressure through the parking brake proportional valve.

6. A tractor braking method according to claim 4, characterized in that, The steps for applying the parking brake include: when the tractor malfunctions and cannot be started, close the emergency valve and release the brake by manually pressurizing the pump.

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