Underground shovel and gear control system

Abstract

The application discloses an underground scraper and a gear control system thereof, which is used for controlling a gear device of a vehicle, the gear device having a neutral state and a driving state; the gear control system comprises a brake device, a brake sensor and a neutral electromagnetic valve; wherein the brake device is used for being operated by a user to control the vehicle to slow down or stop; the brake sensor is used for detecting the state of the brake device; the neutral electromagnetic valve makes the gear device switch to the neutral state by switching an oil circuit when the brake sensor detects that the brake device is in a preset state; the gear device and the neutral electromagnetic valve are in hydraulic connection; and the brake sensor and the neutral electromagnetic valve are in electrical connection. The underground scraper and the gear control system thereof provided by the application can make the gear device automatically switch to the neutral state when the brake is applied, thereby avoiding at least energy loss.

Description

Technical Field

[0001] This application belongs to the field of underground loader control, and more specifically, relates to an underground loader and its gear control system. Background Technology

[0002] Currently, most underground loader transmissions are manual. When braking, the transmission cannot automatically shift to neutral. The transmission remains in the current gear, causing the torque converter to stall, generating excessive heat, increasing engine load, and consuming too much energy, resulting in unnecessary waste. Furthermore, frequent torque converter stalls can affect the lifespan of components such as the transmission, axles, and driveshafts, leading to increased maintenance costs. Summary of the Invention

[0003] The summary section of this application is intended to provide a brief overview of the concepts, which will be described in detail in the detailed description section below. This summary section is not intended to identify key or essential features of the claimed technical solutions, nor is it intended to limit the scope of the claimed technical solutions.

[0004] To address the technical problems mentioned in the background section, as a first aspect of this application, some embodiments of this application provide a gear shift control system for controlling the transmission of a vehicle, the transmission having a neutral state and a driving state. The gear shift control system includes a braking device, a brake sensor, and a neutral solenoid valve. The braking device is operated by the user to control the vehicle to decelerate or stop. The brake sensor detects the state of the braking device. When the brake sensor detects that the braking device is in a preset state, the neutral solenoid valve switches the transmission to neutral by switching the hydraulic circuit. The transmission and the neutral solenoid valve are hydraulically connected. The brake sensor and the neutral solenoid valve are electrically connected.

[0005] Furthermore, the braking device includes a pedal and a brake valve. The pedal is for the user to press. The brake valve is used to switch the brake fluid circuit of the braking device to achieve braking when the user presses the pedal.

[0006] Furthermore, the brake sensor is configured as a pressure switch that can detect the pressure of the brake fluid circuit of the braking device.

[0007] Furthermore, the pressure switch and the neutral solenoid valve are connected in the same current circuit so that when the pressure value at the pressure switch is greater than or equal to a preset threshold, the current circuit is turned on or off, thereby energizing or de-energizing the neutral solenoid valve.

[0008] Furthermore, the gear position control system also includes a main controller. This main controller is used to control the neutral solenoid valve. The main controller is electrically connected to the neutral solenoid valve. The brake sensor is also electrically connected to the main controller.

[0009] Furthermore, the braking device includes a pedal and a pedal sensor. The pedal is used by the user to press it. The pedal sensor is used to detect whether the pedal is pressed. The pedal sensor is electrically connected to the main controller.

[0010] Furthermore, the gear control system also includes a key switch. This key switch is used by the user to start or stop the vehicle. The key switch is electrically connected to the main controller.

[0011] Furthermore, the gear control system also includes an engine controller. This engine controller is used to control the engine to start or stop. The engine controller is electrically connected to the main controller.

[0012] Furthermore, the gear control system also includes a parking switch. This parking switch is used by the user to brake the vehicle. The parking switch is electrically connected to the main controller.

[0013] Furthermore, the braking device includes a pedal, a pedal sensor, and a brake valve. The gear control system includes at least two brake sensors, one of which is configured to sense the state of the braking device and convert it into an electrical signal, and the other is configured as a pressure switch.

[0014] As a second aspect of this application, some embodiments of this application claim protection for an underground loader that includes a transmission device and the aforementioned gear control system.

[0015] The beneficial effects of this application are as follows:

[0016] This application provides an underground loader and its gear control system that can automatically switch the transmission to neutral when braking, thereby at least avoiding energy loss.

[0017] More specifically, some embodiments of this application may produce the following specific beneficial effects:

[0018] The neutral solenoid valve of this application switches the transmission to neutral by switching the oil circuit when the brake sensor detects that the brake device is in a preset state. This avoids the hydraulic torque converter from stalling and the fluid in it from generating a lot of heat. At the same time, it avoids the engine load from increasing and consuming too much energy, thus avoiding unnecessary waste.

[0019] The main controller of this application receives electrical signals from the key switch, engine controller, parking switch, pedal sensor and brake sensor and determines whether to provide an electrical signal to the neutral solenoid valve to energize it, thereby avoiding repeated triggering of the neutral solenoid valve in various non-target working scenarios and extending its service life. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application.

[0021] Throughout the accompanying drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the elements are not necessarily drawn to scale.

[0022] In the attached diagram:

[0023] Figure 1 This is a schematic diagram of an underground loader structure according to an embodiment of this application, mainly showing the cab, wheels, and other structures.

[0024] Figure 2 for Figure 1 Architecture diagram of the gear control system in the illustrated embodiment;

[0025] Figure 3 for Figure 2 The schematic diagram of the control loop of a specific embodiment of the gear control system shown in the figure mainly illustrates the structure of the main controller, etc.

[0026] Figure 4 for Figure 3 The circuit diagram of the gear control system in the illustrated embodiment mainly shows the connection relationship between the main controller and the neutral solenoid valve, etc.

[0027] Figure 5 for Figure 4 The logic block diagram of the gear control system in the illustrated embodiment;

[0028] Figure 6 for Figure 2 The circuit diagram of another specific implementation of the gear control system in the illustrated embodiment mainly shows the structure such as the pressure switch;

[0029] Figure 7 for Figure 6 The schematic diagram of the hydraulic circuit of the underground loader in the illustrated embodiment mainly shows the structure such as the pedal;

[0030] Figure 8 for Figure 7 The enlarged schematic diagram at point A mainly shows the structure such as the first oil inlet;

[0031] Figure 9 for Figure 7 The enlarged schematic diagram at point B mainly shows the structure such as the second oil inlet;

[0032] Figure 10 for Figure 7The enlarged schematic diagram at point C mainly shows the structure such as the third oil inlet.

[0033] Meaning of the reference numerals in the attached figures:

[0034] 100. Underground loader; 101. Cab; 102. Wheels; 103. Transmission;

[0035] 200. Gear control system; 210. Neutral solenoid valve; 230. Brake sensor;

[0036] 300. Gear control system; 310. Neutral solenoid valve; 320. Braking device; 321. Pedal sensor; 322. Pedal; 330. Brake sensor; 340. Main controller; 350. Key switch; 360. Engine controller; 370. Parking switch; 380. Display;

[0037] 400. Gear control system; 403. Transmission device; 404. Hydraulic oil tank; 405. Gear pump; 406. Pressure reducing valve; 407. Accumulator; 408. Brake distribution valve; 409. Drive axle; 410. Neutral solenoid valve; 411. Coil; 412. Valve core; 412a. First oil inlet; 412b. First oil outlet; 412c. Second oil outlet; 420. Braking device; 421. Brake valve; 421a. Second oil inlet; 421b. Third oil outlet; 421c. First control oil port; 422. Pedal; 422a. Third oil inlet; 422b. Fourth oil outlet; 422c. Second control oil port; 430. Brake sensor; 431. Pressure switch; 440. Power supply. Detailed Implementation

[0038] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0039] It should also be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. Features in the embodiments of this disclosure can be combined with each other unless otherwise specified.

[0040] It should be noted that the concepts of "first" and "second" mentioned in this disclosure are used only to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependencies.

[0041] It should be noted that the terms "a" and "a plurality of" used in this disclosure are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0042] This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0043] Reference Figures 1 to 2 As shown, this embodiment provides an underground shovel loader 100, which includes a cab 101, wheels 102, a transmission 103, and a gear control system 200. The cab 101 accommodates the user and allows the user to drive the underground shovel loader 100. The transmission 103 controls the rotational speed of the wheels 102. The gear control system 200 controls the gear position of the transmission 103, which has a neutral position and a drive position. The gear control system 200 includes a brake device 320, a brake sensor 230, and a neutral solenoid valve 210. The brake device 320 is operated by the user to control the underground shovel loader 100 to decelerate or stop. The brake sensor 230 detects the state of the brake device 320. When the brake sensor 230 detects that the brake device 320 is in a preset state, the neutral solenoid valve 210 switches the transmission 103 to neutral by switching the oil circuit. The transmission 103 and the neutral solenoid valve 210 are hydraulically connected. The brake sensor 230 is electrically connected to the neutral solenoid valve 210. The specific connections between the various parts of the gear control system 200 will be described in detail later.

[0044] Specifically, refer to Figures 3 to 5 As shown, in one specific embodiment of the gear control system 300, the brake sensor 330 is configured as a sensor capable of sensing the state of the brake device 320 and converting it into an electrical signal, such as a resistive sensor or a piezoelectric sensor. This is a technical solution well known to those skilled in the art and will not be described in detail here.

[0045] The gear control system 300 also includes a main controller 340. The main controller 340 controls the neutral solenoid valve 310. The main controller 340 is electrically connected to the neutral solenoid valve 310. The brake sensor 330 is electrically connected to the main controller 340. The brake device 320 includes a pedal 322 and a pedal sensor 321. The pedal 322 is for the user to press. The pedal sensor 321 detects whether the pedal 322 is pressed. The pedal sensor 321 is electrically connected to the main controller 340.

[0046] Using the above technical solution, the main controller 340 determines whether the pedal 322 is pressed by the electrical signal transmitted by the pedal 322 sensor. If the pedal 322 is pressed, it determines whether the braking device 320 has reached a preset state by the electrical signal transmitted by the brake sensor 330. If the preset state is reached, it sends an electrical signal to the neutral solenoid valve 310. When the user presses the pedal 322 and the braking device 320 reaches the preset state, the main controller 340 sends an electrical signal to the neutral solenoid valve 310 to energize it, thereby switching the transmission to neutral. When the user releases the pedal 322 and the braking device 320 changes to a non-preset state, the neutral solenoid valve is de-energized, and the transmission automatically switches back to drive mode.

[0047] More specifically, the gear control system 300 also includes a key switch 350. This key switch 350 is used by the user to start or stop the vehicle. The key switch 350 is electrically connected to the main controller 340.

[0048] With the above technical solution, if the key switch 350 is not turned on, even if the pedal 322 is pressed, the neutral solenoid valve 310 will not be energized, preventing the user from triggering the neutral solenoid valve 310 by pressing the pedal 322 when the key switch 350 is not turned on, thus avoiding the neutral solenoid valve 310 being triggered in the non-target working scenario where the key switch 350 is not turned on, which would shorten its service life.

[0049] More specifically, the gear control system 300 also includes an engine controller 360. The engine controller 360 is used to control the engine to start or stop. The engine controller 360 is electrically connected to the main controller 340.

[0050] With the above technical solution, if the key switch 350 is turned on but the engine is not started, the neutral solenoid valve 310 will not be energized even if the pedal 322 is pressed. This prevents the user from triggering the neutral solenoid valve 310 by pressing the pedal 322 when the key switch 350 is turned on but the engine is not started. This further avoids the neutral solenoid valve 310 being triggered in the non-target working scenario when the engine is not running, which would shorten its service life.

[0051] More specifically, the gear control system 300 also includes a parking switch 370. This parking switch 370 is used to brake the vehicle. The parking switch 370 is electrically connected to the main controller 340.

[0052] Using the above technical solution, when the key switch 350 is turned on and the engine is running, if the parking switch 370 is not released, the underground loader is braked and in a non-driving state. In this state, even if the user presses the pedal 322, the main controller 340 judges the electrical signal transmitted from the parking switch 370, and the neutral solenoid valve 310 remains de-energized, thus avoiding the neutral solenoid valve 310 being triggered in the non-target working scenario when the parking switch 370 is not released, which would shorten its service life.

[0053] More specifically, the gear control system 300 also includes a display 380. The display 380 is used to display neutral information. The display 380 is electrically connected to the main controller 340.

[0054] Using the above technical solution, when the transmission device is switched to neutral, the display 380 displays neutral information to prompt the user that the current status of the transmission device is neutral, so that the user can observe the status of the transmission device in real time. The user can also use the display 380 to assist in checking whether the gear control system 300 is operating normally.

[0055] As a specific solution of the above embodiments, refer to Figure 5 As shown, the main controller 340 in the gear control system 300 makes the following judgments during actual operation:

[0056] S1: Receive the electrical signal transmitted by the key switch 350 and determine whether the key switch 350 is open. If the key switch 350 is closed, the neutral solenoid valve 310 is de-energized; if the key switch 350 is open, proceed to the next step.

[0057] S2: Receives electrical signals from engine controller 360 and determines whether the engine is started. If the engine is off, neutral solenoid valve 310 is de-energized; if the engine is started, proceed to the next step.

[0058] S3: Receive the electrical signal transmitted by the parking switch 370 and determine whether the parking switch 370 is released. If the parking switch 370 is not released, the neutral solenoid valve 310 is de-energized; if the parking switch 370 is released, proceed to the next step.

[0059] S4: Receive the electrical signal transmitted by the pedal 322 sensor and determine whether the pedal 322 is pressed. If the pedal 322 is not pressed, the neutral solenoid valve 310 is de-energized; if the pedal 322 is pressed, proceed to the next step.

[0060] S5: Receive the electrical signal transmitted by the brake sensor 330 and determine whether the brake device 320 has reached the preset state. If the brake device 320 has not reached the preset state, the neutral solenoid valve 310 is de-energized; if the brake device 320 has reached the preset state, the neutral solenoid valve 310 is energized, the transmission device is switched to neutral, and the display 380 displays the neutral information.

[0061] The transmission device is not shown in the figures in the above embodiments.

[0062] More specifically, refer to Figure 6 As shown, as another specific implementation of the gear control system 400 in the above embodiments, the difference from the above embodiments is that the gear control system 400 in this embodiment also includes a power supply 440. One end of the power supply 440 is electrically connected to one end of the brake sensor 430, and the other end of the brake sensor 430 is electrically connected to one end of the neutral solenoid valve 410. The other end of the neutral solenoid valve 410 is electrically connected to the other end of the power supply 440. The brake sensor 430 is used to detect the state of the brake device 420. It should be noted that the positive terminal of the power supply 440 is electrically connected to the neutral solenoid valve, and the negative terminal of the power supply 440 is electrically connected to the pressure switch 431. Of course, the positive and negative terminals of the power supply 440 can be interchanged.

[0063] More specifically, refer to Figures 7 to 10 As shown, the braking device 420 includes a pedal 422 and a brake valve 421. The pedal 422 is for the user to press. The brake valve 421 is used to switch the brake fluid circuit of the braking device 420 to achieve braking when the user presses the pedal 422. The brake sensor 430 is configured as a pressure switch 431 that can detect the pressure of the brake fluid circuit of the braking device 420. The pressure switch 431 is connected to the neutral solenoid valve 410 in the same current circuit so that when the pressure value at the pressure switch 431 is greater than or equal to a preset threshold, the current circuit is opened or closed, thereby energizing or de-energizing the neutral solenoid valve 410.

[0064] More specifically, in this embodiment, the gear control system 400 is hydraulically connected to a hydraulic oil tank 404, a gear pump 405, a pressure reducing valve 406, an accumulator 407, a brake distribution valve 408, and a drive axle 409. The neutral solenoid valve 410 is configured as a two-position three-way solenoid valve, comprising a coil 411 and a valve core 412. A pressure switch 431 is connected to the coil 411 via a... Figure 6The current circuit shown causes the pressure switch 431 to control the presence or absence of current in the control coil 411, thereby controlling the position of the valve core 412. The valve core 412 includes a first oil inlet 412a, a first oil outlet 412b, and a second oil outlet 412c. The valve core 412 has a first working position and a second working position. When the valve core 412 is in the first working position, the first oil inlet 412a is connected to the first oil outlet 412b, and the first oil outlet 412b is in a blocked state. When the valve core 412 is in the second working position, the first oil inlet 412a is connected to the second oil outlet 412c, and the second oil outlet 412c is hydraulically connected to the hydraulic oil tank 404. One end of the gear pump 405 is hydraulically connected to the hydraulic oil tank 404, one end of the pressure reducing valve 406 is connected to the other end of the gear pump 405, one end of the transmission device 403 is hydraulically connected to the other end of the pressure reducing valve 406, and the end of the transmission device 403 connected to the pressure reducing valve 406 is hydraulically connected to the first oil inlet 412a of the valve core 412.

[0065] One end of the accumulator 407 is hydraulically connected to the other end of the gear pump 405. The brake valve 421 includes a second inlet 421a, a third outlet 421b, and a first control port 421c. The second inlet 421a is hydraulically connected to the other end of the accumulator 407, and the third outlet 421b is hydraulically connected to the hydraulic oil tank 404. The pedal 422 includes a third inlet 422a, a fourth outlet 422b, and a second control port 422c. The third inlet 422a is hydraulically connected to the first control port 421c, and the second control port 422c is hydraulically connected to one end of the brake distribution valve 408. The fourth outlet 422b is hydraulically connected to the hydraulic oil tank 404. The first control port is hydraulically connected to the other end of the brake distribution valve 408. The brake distribution valve 408 is hydraulically connected to the drive axle 409 to decelerate or stop the wheels. A pressure switch 431 detects the pressure of the hydraulic oil in the brake distribution valve 408 and closes when the pressure reaches a preset threshold. It should be noted that there are two brake solenoid valves in the figure. They have the same structure and play the same role in the hydraulic circuit. The purpose of setting two brake valves 421 in the hydraulic circuit is to prevent the brake device 420 from not working properly if one of the brake valves 421 fails.

[0066] Using the above technical solution, when the user presses the pedal 422, the pressure of the hydraulic oil in the brake distribution valve 408 increases. The pressure switch 431 detects the pressure and closes when the pressure reaches a preset threshold, thereby connecting the current circuit of the neutral solenoid valve 410, energizing the neutral solenoid valve 410, and moving the valve core 412 from the first working position to the second working position. The first oil inlet 412a and the second oil outlet 412c are connected, changing the flow direction of the hydraulic oil that originally flowed from the pressure reducing pump to the transmission device 403, so that it flows from the pressure reducing pump through the valve core 412 to the hydraulic oil tank 404, thus putting the transmission device 403 into neutral.

[0067] When the user presses pedal 422, the wheels, due to the action of brake device 420, reduce their rotation speed or stop rotating. If the transmission device 403 maintains its current driving state at this time, the hydraulic torque converter in the underground loader, after transferring the engine's mechanical energy to the fluid, cannot effectively transfer it to the output shaft, causing the hydraulic torque converter to stall. The fluid in the torque converter generates a large amount of heat, increasing the engine load, consuming excessive energy, and causing unnecessary waste. Furthermore, frequent stalling of the torque converter will affect the service life of components such as the gearbox, drive axle 409, input shaft, and output shaft, leading to increased maintenance costs. In this embodiment, when the user presses pedal 422, pressure switch 431 detects the pressure in brake device 420 and closes when it reaches a preset threshold. Neutral solenoid valve 410 is energized, and transmission device 403 switches to neutral. The input and output shafts of the underground loader are separated, and the output shaft can rotate under the action of the fluid in the hydraulic torque converter. This avoids the fluid generating a large amount of heat and causing damage to the engine, thereby extending the service life of related components and reducing the maintenance cost of the underground loader. The hydraulic torque converter, input shaft, output shaft, and engine are standard components in underground loader and are not shown in the figure.

[0068] Furthermore, in this embodiment, when the user presses the pedal 422 and the pressure in the brake device 420 reaches a certain level, the transmission device 403 automatically switches to neutral. When the user releases the pedal 422 and the pressure in the oil circuit drops below the preset threshold, the neutral solenoid valve 410 is de-energized, the valve core 412 moves back to the first working position, and the gear in the transmission device 403 automatically returns to the driving state before the pedal 422 was pressed. The entire process does not require the user to manually shift gears.

[0069] As an extension, a combination of the two embodiments described above can be used to improve the reliability of the control system, while still enabling the automatic neutral function in the event of a main controller failure.

[0070] This application has been described in detail above with reference to specific exemplary embodiments. However, it should be understood that various modifications and variations can be made without departing from the scope of this application as defined by the appended claims. The detailed description and drawings should be considered illustrative only and not restrictive, and any such modifications and variations shall fall within the scope of this application described herein. Furthermore, the background art is intended to illustrate the current state of research and development and significance of the technology, and is not intended to limit this application or its application field.

[0071] More specifically, although exemplary embodiments of this application have been described herein, this application is not limited to these embodiments, but includes any and all embodiments modified, omitted, such as combinations between various embodiments, adaptive changes, and / or substitutions, as would be apparent to those skilled in the art from the foregoing detailed description. The limitations in the claims are to be interpreted broadly as used in the language of the claims and are not limited to the examples described in the foregoing detailed description or during the implementation of this application, which should be considered non-exclusive. Any step enumerated in any method or process claim may be performed in any order and is not limited to the order presented in the claims. Therefore, the scope of this application should be determined solely by the appended claims and their legal equivalents, and not by the description and examples given above.

Claims

1. A gear control system for controlling a transmission device of a vehicle, the transmission device having a neutral state and a drive state; The gear control system includes: Braking system, used by the user to control the vehicle to decelerate or stop; Its features are: The gear control system also includes: A brake sensor is used to detect the status of the braking device; The neutral solenoid valve switches the transmission to neutral by switching the oil circuit when the brake sensor detects that the brake device is in a preset state. The transmission device is hydraulically connected to the neutral solenoid valve; the brake sensor is electrically connected to the neutral solenoid valve. The brake sensor is constructed as a pressure switch; the neutral solenoid valve includes a coil and a valve core; the pressure switch controls the presence or absence of current in the coil, thereby controlling the position of the valve core; The valve core includes a first oil inlet, a first oil outlet, and a second oil outlet. The valve core has a first working position and a second working position. When the valve core is in the first working position, the first oil inlet is connected to the first oil outlet, and the first oil outlet is in a blocked state. When the valve core is in the second working position, the first oil inlet of the valve core is connected to the second oil outlet, and the second oil outlet is hydraulically connected to the hydraulic oil tank. One end of the gear pump is hydraulically connected to the hydraulic oil tank, one end of the pressure reducing valve is connected to the other end of the gear pump, one end of the speed change device is hydraulically connected to the other end of the pressure reducing valve, and the end of the speed change device connected to the pressure reducing valve is hydraulically connected to the first oil inlet of the valve core. One end of the accumulator is hydraulically connected to the other end of the gear pump; the brake valve includes a second inlet, a third outlet, and a first control port, with the second inlet hydraulically connected to the other end of the accumulator and the third outlet hydraulically connected to the hydraulic oil tank; the pedal includes a third inlet, a fourth outlet, and a second control port, with the third inlet hydraulically connected to the first control port and the second control port hydraulically connected to one end of the brake distribution valve; the fourth outlet is hydraulically connected to the hydraulic oil tank; the first control port is hydraulically connected to the other end of the brake distribution valve; the brake distribution valve is hydraulically connected to the drive axle to decelerate or stop the wheels; a pressure switch detects the pressure of the hydraulic oil in the brake distribution valve and closes when the pressure reaches a preset threshold. When the user presses the pedal, the pressure of the hydraulic oil in the brake distribution valve increases. The pressure switch detects the pressure and closes when the pressure reaches a preset threshold, thereby connecting the current circuit of the neutral solenoid valve. This energizes the neutral solenoid valve, causing the valve core to move from the first working position to the second working position. The first oil inlet and the second oil outlet are connected, changing the flow direction of the hydraulic oil that originally flowed from the pressure reducing pump to the transmission. Instead, the oil flows from the pressure reducing pump through the valve core to the hydraulic oil tank, thus putting the transmission into neutral.

2. The gear control system according to claim 1, characterized in that: The braking device includes: A pedal, used by the user to step on it; A brake valve is used to switch the brake fluid circuit of the braking device to achieve braking when the user presses the pedal.

3. The gear control system according to claim 2, characterized in that: The pressure switch is connected to the neutral solenoid valve in the same current circuit so that when the pressure value at the pressure switch is greater than or equal to a preset threshold, the neutral solenoid valve is energized or de-energized by turning on or off the current circuit.

4. The gear control system according to claim 1, characterized in that: The gear control system also includes: The main controller is used to control the neutral solenoid valve; The main controller is electrically connected to the neutral solenoid valve; the brake sensor is electrically connected to the main controller.

5. The gear control system according to claim 4, characterized in that: The braking device includes: A pedal, used by the user to step on it; A pedal sensor is used to detect whether the pedal is being stepped on; The foot sensor is electrically connected to the main controller.

6. The gear control system according to claim 5, characterized in that: The gear control system also includes: The key switch is used by the user to start or stop the vehicle. The key switch is electrically connected to the main controller.

7. The gear control system according to claim 6, characterized in that: The gear control system also includes: Engine controller, used to control the engine to start or stop; The engine controller and the main controller are electrically connected.

8. The gear control system according to claim 7, characterized in that: The gear control system also includes: Parking switch, used to allow the user to brake the vehicle; The parking switch is electrically connected to the main controller.

9. An underground loader, characterized in that: It includes a transmission device and a gear control system as described in any one of claims 1 to 8.

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