Digging end steering system of backhoe loader and control method

Abstract

The invention discloses an excavation end steering system of a backhoe loader and a control method. The system comprises an excavation end steering control component, an excavation end oil pumping branch and an excavation end oil return branch. If the vehicle-mounted controller receives a left steering signal output by the excavation end steering control component, the vehicle-mounted controller controls an excavation end oil pumping branch to be communicated with a left steering oil supply path and controls an excavation end oil return branch to be communicated with a right steering oil supply path; and if the vehicle-mounted controller receives a right steering signal output by the excavation end steering control component, the vehicle-mounted controller controls the excavation end oil pumping branch to be communicated with the right steering oil supply path and controls the excavation end oil return branch to be communicated with the left steering oil supply path. The excavating end steering system is additionally arranged on an existing excavating loader, the moving direction of the excavating loader can be directly controlled at the excavating end when the excavating end works, a driver does not need to operate a steering wheel on the back, and convenience and safety are achieved.

Description

Technical Field

[0001] This invention relates to a digging end steering system and control method for a backhoe loader, belonging to the field of backhoe loaders. Background Technology

[0002] Excavator loaders are multi-functional engineering machines that integrate excavation, loading, and movement. Their steering is generally operated through a steering wheel, which in turn drives the steering gear through the steering column, thereby controlling the movement of the steering cylinder to achieve steering.

[0003] Excavator loaders have a loading end and an excavating end. Steering is usually done by operating the steering wheel when facing the loading end. However, when working facing the excavating end, the seat is turned towards the excavating end (i.e., the driver's back is to the steering wheel). When it is necessary to control the movement of the vehicle, the driver needs to operate the steering wheel with his back to the driver and also operate the control mechanism of the excavating end, which is very inconvenient and unsafe. Summary of the Invention

[0004] This invention provides a digging end steering system and control method for an excavator loader, which solves the problems disclosed in the background art.

[0005] According to one aspect of this application, a digging end steering system for a backhoe loader is provided, including a digging end steering control component, a digging end oil pump branch, and a digging end oil return branch; If the vehicle controller receives a left turn signal from the excavator end steering control component, the vehicle controller controls the excavator end pump oil branch to connect with the left turn oil supply line, controls the pump component in the excavator end pump oil branch to pump hydraulic oil to the left turn oil supply line, and controls the excavator end return oil branch to connect with the right turn oil supply line. If the vehicle controller receives a right turn signal from the excavator end steering control component, the vehicle controller controls the excavator end pump oil branch to connect with the right turn oil supply line, controls the pump component in the excavator end pump oil branch to pump hydraulic oil to the right turn oil supply line, and controls the excavator end return oil branch to connect with the left turn oil supply line.

[0006] Furthermore, the on-board controller controls the connection between the branch circuit and the fuel supply circuit via the first solenoid valve; The first oil port, second oil port, third oil port, and fourth oil port of the first solenoid valve are respectively connected to the excavator end pump oil branch, the excavator end return oil branch, the left turn oil supply line, and the right turn oil supply line; If the vehicle controller receives a left turn signal from the digging end steering control component, the vehicle controller controls the first oil port and the third oil port to connect, and the second oil port and the fourth oil port to connect. If the vehicle controller receives a right turn signal from the digging end steering control component, the vehicle controller controls the first and fourth oil ports to connect, and the second and third oil ports to connect.

[0007] Furthermore, the excavator end return oil branch includes a return oil pipeline and a third solenoid valve installed on the return oil pipeline. The vehicle controller controls the opening and closing of the return oil pipeline through the third solenoid valve.

[0008] Furthermore, the oil pump branch at the excavator end also includes an oil pump pipeline, a drive unit, and a second solenoid valve; The on-board controller controls the start and stop of the oil pump components through the drive unit; Driven by the drive unit, the oil pumping component pumps hydraulic oil through the oil pumping pipeline to the left turn oil supply circuit or the right turn oil supply circuit; The second solenoid valve is installed on the oil pump line, and the vehicle controller controls the opening and closing of the oil pump line through the second solenoid valve.

[0009] Furthermore, the excavator end pump oil branch also includes an excavator end steering safety valve. The first oil port of the excavator end steering safety valve is located on the pump oil pipeline between the second solenoid valve and the pump oil component, and the second oil port of the excavator end steering safety valve is connected to the hydraulic oil tank.

[0010] Furthermore, the system also includes a vehicle speed sensing device. If the vehicle controller determines that the vehicle speed sensed by the vehicle speed sensing device is less than a threshold, the vehicle controller will then control the connection between the branch circuit and the fuel supply circuit.

[0011] Furthermore, the system also includes a digging end steering activation switch. If the vehicle controller receives a steering activation signal output by the digging end steering activation switch, the vehicle controller will receive the vehicle speed sensed by the vehicle speed sensor and determine the vehicle speed.

[0012] Furthermore, the digging end steering control component is a digging end handle wheel or button.

[0013] According to another aspect of this application, a digging end steering control method for a backhoe loader is provided, employing the aforementioned digging end steering system of the backhoe loader for steering, the method comprising: In response to receiving the left turn signal output by the digging end steering control component, the digging end pump oil branch is connected to the left turn oil supply line, the pumping component in the digging end pump oil branch is controlled to pump hydraulic oil to the left turn oil supply line, and the digging end return oil branch is connected to the right turn oil supply line. In response to receiving a right turn signal from the excavator end steering control unit, the system controls the excavator end pump oil branch to connect with the right turn oil supply line, controls the pumping unit in the excavator end pump oil branch to pump hydraulic oil to the right turn oil supply line, and controls the excavator end return oil branch to connect with the left turn oil supply line.

[0014] The beneficial effects achieved by the present invention are as follows: The present invention is a digging end steering system added to an existing excavator loader. The digging end steering control component outputs a steering signal, and the vehicle controller pumps hydraulic oil to the left steering oil supply circuit or the right steering oil supply circuit according to the steering signal. The digging end loader can be directly controlled to move in the direction of the excavator loader when working at the digging end, without the need for the driver to turn his back to operate the steering wheel, which is convenient and safe. Attached Figure Description

[0015] Figure 1 This is a first structural block diagram of the digging end steering system of a backhoe loader; Figure 2 This is a schematic diagram of the digging end steering system of an excavator loader. Figure 3 This is a second structural block diagram of the digging end steering system of a backhoe loader. Detailed Implementation

[0016] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0017] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application.

[0018] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0019] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0020] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0021] It should be noted that similar symbols and letters in the following figures represent similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0022] Furthermore, in the description of the embodiments of this application, the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. Therefore, features defined with "first" or "second" may explicitly or implicitly include one or more features.

[0023] To address the problems of inconvenient and unsafe steering of existing backhoe loaders during excavation operations, this application proposes an excavation end steering system for backhoe loaders, specifically by connecting an excavation end steering system in parallel with the existing loading end steering system of backhoe loaders.

[0024] See Figure 1 , Figure 1 This is a structural block diagram of a digging end steering system for a backhoe loader provided in an embodiment of this application. The system may include at least a digging end steering control component, a digging end oil pump branch, and a digging end return oil branch. If the vehicle controller 1 receives a left turn signal output by the digging end steering control component, the vehicle controller 1 controls the digging end oil pump branch to connect with the left turn oil supply line, controls the oil pumping component in the digging end oil pump branch to pump hydraulic oil to the left turn oil supply line 3, and controls the digging end return oil branch to connect with the right turn oil supply line 4. If the vehicle controller 1 receives a right turn signal output by the digging end steering control component, the vehicle controller 1 controls the digging end oil pump branch to connect with the right turn oil supply line 4, controls the oil pumping component in the digging end oil pump branch to pump hydraulic oil to the right turn oil supply line 4, and controls the digging end return oil branch to connect with the left turn oil supply line 3.

[0025] It should be noted that the digging end steering control component can be an independent steering control device installed on the digging end, such as a handle. However, in order to reduce costs, in some embodiments, the digging end steering control component can adopt the existing digging end handle roller 2 or digging end button. Generally, the digging end handle roller 2 is adopted. The digging end handle roller 2 can realize three positions, namely the middle position, the left scroll position, and the right scroll position. Among them, the middle position indicates no steering and can send a no steering signal. The left scroll position will send a left steering signal to the vehicle controller 1, and the right scroll position will send a right steering signal to the vehicle controller 1.

[0026] It should be noted that the vehicle-mounted controller 1 can be a new independent controller or an existing controller in the excavator loader. Generally, in order to reduce costs, the existing controller in the excavator loader is used.

[0027] See Figure 1 In order to facilitate the connection between the control branch and the fuel supply line, all fuel supply lines and branch lines can be connected to a switching device. The vehicle controller 1 can realize the connection between different branch lines and different fuel supply lines by controlling the switching device.

[0028] See Figure 2 In some embodiments, the switching device may employ a first solenoid valve 13, that is, the vehicle controller 1 controls the connection between the branch and the oil supply line through the first solenoid valve 13.

[0029] The first oil port (i.e., port a in the figure), the second oil port (i.e., port b in the figure), the third oil port (i.e., port c in the figure), and the fourth oil port (i.e., port d in the figure) of the first solenoid valve 13 are respectively connected to the excavator end pump oil branch, the excavator end return oil branch, the left turn oil supply line 3, and the right turn oil supply line 4; if the vehicle controller 1 receives the left turn signal output by the excavator end steering control component, the vehicle controller 1 controls the first oil port and the third oil port to connect, and the second oil port and the fourth oil port to connect; if the vehicle controller 1 receives the right turn signal output by the excavator end steering control component, the vehicle controller 1 controls the first oil port and the fourth oil port to connect, and the second oil port and the third oil port to connect.

[0030] The control of the first solenoid valve 13 mainly involves controlling the de-energization and energization of the electromagnet of the first solenoid valve 13. When the electromagnet of the first solenoid valve 13 is de-energized, the first oil port and the third oil port are connected, and the second oil port and the fourth oil port are connected. When the electromagnet of the first solenoid valve 13 is energized, the first oil port and the fourth oil port are connected, and the second oil port and the third oil port are connected.

[0031] It should be noted that the excavator end return oil branch mainly includes a return oil pipeline, which connects the first solenoid valve 13 and the hydraulic oil tank. However, for easier control of the branch, please refer to [reference needed]. Figure 2 In some embodiments, a third solenoid valve 14 is installed on the return oil line, and the vehicle controller 1 can control the opening and closing of the return oil line through the third solenoid valve 14.

[0032] The control of the third solenoid valve 14 is similar to that of the first solenoid valve 13. When the electromagnet of the third solenoid valve 14 is de-energized, the flow in the return direction is cut off, that is, the flow from the first solenoid valve 13 to the hydraulic oil tank is cut off (i.e., the flow from port e to port f in the diagram is cut off), while the flow in the opposite direction of the return is normal, that is, the flow from the hydraulic oil tank to the first solenoid valve 13 is normal (i.e., the flow from port f to port e in the diagram is normal). When the electromagnet of the third solenoid valve 14 is energized, the flow in the return direction is normal, and the flow in the opposite direction of the return is normal.

[0033] Similar to the return oil branch at the excavator end, the pump oil branch at the excavator end mainly includes pump oil lines, pump oil components, and a drive unit. The on-board controller 1 controls the start and stop of the pump oil components through the drive unit; driven by the drive unit, the pump oil components pump hydraulic oil through the pump oil lines to the left turn oil supply line 3 or the right turn oil supply line 4.

[0034] It should be noted that the oil pumping component can be an excavator-end steering pump 18, used to pump hydraulic oil from the hydraulic oil tank to the oil pumping line. The drive unit mainly includes an excavator-end steering motor 17 and a relay 16. The output end of the excavator-end steering motor 17 is connected to the excavator-end steering pump 18 to drive the excavator-end steering pump 18 to work. The relay 16 is connected in series between the excavator-end steering motor 17 and the power supply. The vehicle controller 1 controls the on / off of the power supply to the excavator-end steering motor 17 by controlling the relay 16.

[0035] Similarly, for easier control of branch circuits, see [link to relevant documentation]. Figure 2 In some embodiments, a second solenoid valve 15 is also installed on the pump oil line. The vehicle controller 1 controls the opening and closing of the pump oil line through the second solenoid valve 15. The second solenoid valve 15 also controls the de-energization and energization of the electromagnet. When the electromagnet of the second solenoid valve 15 is de-energized, it is cut off in both directions, that is, the flow from the first solenoid valve 13 to the digging end turning pump 18 is cut off (i.e., the flow from port g to port h in the figure is cut off), and the flow from the digging end turning pump 18 to the first solenoid valve 13 is also cut off (i.e., the flow from port h to port g in the figure is cut off). Conversely, when it is energized, it is normal in both directions.

[0036] See Figure 2 In some embodiments, the excavator end pump oil branch also includes an excavator end steering safety valve 19. The first port of the excavator end steering safety valve 19 is connected to the pump oil pipeline between the second solenoid valve 15 and the pump oil component (i.e., the excavator end steering pump 18), and the second port of the excavator end steering safety valve 19 is connected to the hydraulic oil tank.

[0037] To prevent accidental steering, see Figure 3 In some embodiments, a vehicle speed sensing device and an excavator end steering activation switch 7 are also added; wherein, the vehicle speed sensing device can be a vehicle speed sensor 5, and the excavator end steering activation switch 7 can be a button.

[0038] The excavator end is only allowed to turn when the vehicle is not in motion. Therefore, the vehicle controller 1 receives the vehicle speed sensed by the vehicle speed sensor 5. When the vehicle speed is less than the threshold (2.5km / h), the vehicle controller 1 controls the connection between the branch and the oil supply line, that is, performs steering control. If the vehicle speed is not less than the threshold (2.5km / h), it is judged as a misoperation and steering control will not be performed.

[0039] The excavator end steering activation switch 7 is a master control switch. When pressed, it sends a steering activation signal to the vehicle controller 1. When pressed again, it sends a steering deactivation signal to the vehicle controller 1. Only after receiving the steering activation signal will the vehicle controller 1 perform excavator end steering control, that is, receive and judge the vehicle speed, and then perform steering control.

[0040] It should be noted that in some embodiments, an instrument panel 6 connected to the vehicle controller 1 will also be added. When a misoperation is detected, the instrument panel 6 can be controlled to issue a warning signal. The instrument panel 6 interface will display "Excavator end steering switch misoperation" accompanied by a continuous "beep" sound warning. The alarm text and sound of the instrument panel 6 can be turned off by pressing the excavator end steering enable switch 7 again, or it will automatically turn off after 1 minute. When the excavator end steering control is entered, the instrument panel 6 can be controlled to issue a warning signal. The instrument panel 6 interface will display "Excavator end steering mode function enabled" accompanied by an intermittent "beep" sound warning. The alarm text and sound of the instrument panel 6 can be turned off by pressing the excavator end steering enable switch 7 again, or it will automatically turn off after 1 minute.

[0041] by Figure 2 Taking the structure of the excavator as an example, the working process of the digging end steering system of the excavator loader is described as follows: Figure 2 The conventional working pump 8, steering priority valve 9, steering gear 10, and steering cylinder 20 constitute the loading end steering system of the existing excavator loader. The output end of the conventional working pump 8 is connected to the P port of the steering priority valve 9 through a pipeline. The CF port of the steering priority valve 9 is connected to the P port of the steering gear 10. The LS port of the steering priority valve 9 is connected to the LS port of the steering gear 10. The steering wheel 11 drives the steering valve 12 of the steering gear 10 to move through a mechanical structure. The L port of the steering priority valve 9 is connected to the left steering port of the steering cylinder 20 through the left steering oil supply line 3. The R port of the steering priority valve 9 is connected to the right steering port of the steering cylinder 20 through the right steering oil supply line 4.

[0042] When the on-board controller 1 detects that the digging end steering activation switch 7 is not pressed, the first solenoid valve 13, the second solenoid valve 15, the third solenoid valve 14, and the relay 16 are all de-energized, and the digging end handle roller 2 controls normal operation. At this time, it is the normal steering mode. Turning the steering wheel 11, the steering wheel 11 drives the steering valve of the steering gear 10 through the mechanical structure, thereby delivering hydraulic oil to the steering cylinder 20 through the pipeline to achieve steering (this steering method is an existing method and will not be described in detail here).

[0043] Figure 2 Intermediate relay 16, excavator end steering motor 17, excavator end steering pump 18, first solenoid valve 13, second solenoid valve 15, third solenoid valve 14, excavator end steering safety valve 19, and Figure 3 The digging end steering system consists of the digging end handle roller 2, the instrument 6, the vehicle speed sensor 5, and the digging end steering activation switch 7. When the vehicle controller 1 detects that the excavator end steering activation switch 7 is pressed, it detects the vehicle speed signal sensed by the vehicle speed sensor 5. If the vehicle speed is greater than or equal to the threshold, it is judged as a misoperation. The vehicle controller 1 sends a warning signal to the instrument panel 6. The instrument panel 6 displays "Excavator end steering switch misoperation" and is accompanied by a continuous "beep" warning sound. At this time, the first solenoid valve 13, the second solenoid valve 15, the third solenoid valve 14, and the relay 16113 are all de-energized. The excavator end handle roller 2 controls the normal operation. The alarm text and sound on the instrument panel 6 can be turned off by pressing the excavator end steering activation switch 7 again, or it will turn off automatically after 1 minute.

[0044] When the vehicle controller 1 detects that the excavator end steering activation switch 7 is pressed, it detects the vehicle speed signal sensed by the vehicle speed sensor 5. If the vehicle speed is less than the threshold, the excavator end steering mode is entered. The vehicle controller 1 sends a warning signal to the instrument panel 6, and the instrument panel 6 displays "Excavator end steering mode function activated" accompanied by intermittent "beep" warning sounds. The vehicle controller 1 will further detect the status of the excavator end handle roller 2. When the excavator end handle roller 2 is in the neutral position, the first solenoid valve 13, the second solenoid valve 15, the third solenoid valve 14, and the relay 16 are all de-energized. When the excavator end handle roller 2 is in the left rolling position, the first solenoid valve 13 is in the state of supplying oil to the left turn oil supply circuit 3, and the second solenoid valve 15, the third solenoid valve 14, and the relay 16 are all energized, and at this time it is in the left turn mode. When the excavator handle roller 2 is in the right-rolling position, the first solenoid valve 13 is in the state of supplying oil to the right-turning oil supply circuit 4, and the second solenoid valve 15, the third solenoid valve 14, and the relay 16 are all energized, and at this time it is in the right-turning mode.

[0045] The above system is an excavator end steering system added to an existing excavator loader. The excavator end steering control component outputs steering signals. The vehicle controller 1 pumps hydraulic oil to the left steering oil supply line 3 or the right steering oil supply line 4 according to the steering signals. The excavator loader can be directly controlled at the excavator end during excavation work without the need for the driver to operate the steering wheel 11 with their back to the machine, which is convenient and safe.

[0046] Based on the above system, this application discloses a digging end steering control method for a backhoe loader, specifically employing the above system for steering. This control method can be implemented by an on-board controller 1, and the method may include at least: Step 1: In response to receiving the left turn signal output by the excavator end steering control component, control the excavator end pump oil branch to connect with the left turn oil supply line 3, control the pump component in the excavator end pump oil branch to pump hydraulic oil to the left turn oil supply line 3, and control the excavator end return oil branch to connect with the right turn oil supply line 4.

[0047] Step 2: In response to receiving the right turn signal output by the excavator end steering control component, control the excavator end pump oil branch to connect with the right turn oil supply line 4, control the pump component in the excavator end pump oil branch to pump hydraulic oil to the right turn oil supply line 4, and control the excavator end return oil branch to connect with the left turn oil supply line 3.

[0048] The above method is implemented by the vehicle controller 1. By receiving the steering signal output by the steering control component at the excavation end, the hydraulic oil pump is controlled to supply oil to the left steering oil circuit 3 or the right steering oil circuit 4. The direction of movement of the excavator loader can be directly controlled at the excavation end when working at the excavation end, without the need for the driver to operate the steering wheel 11 with their back to the ground, which is convenient and safe.

[0049] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention.

Claims

1. A digging end steering system for a backhoe loader, characterized in that, This includes the digging end steering control unit, the digging end oil pump branch, and the digging end return oil branch; If the vehicle controller receives a left turn signal from the excavator end steering control component, the vehicle controller controls the excavator end pump oil branch to connect with the left turn oil supply line, controls the pump component in the excavator end pump oil branch to pump hydraulic oil to the left turn oil supply line, and controls the excavator end return oil branch to connect with the right turn oil supply line. If the vehicle controller receives a right turn signal from the excavator end steering control component, the vehicle controller controls the excavator end pump oil branch to connect with the right turn oil supply line, controls the pump component in the excavator end pump oil branch to pump hydraulic oil to the right turn oil supply line, and controls the excavator end return oil branch to connect with the left turn oil supply line.

2. The system according to claim 1, characterized in that, The vehicle controller controls the connection between the branch circuit and the fuel supply circuit through the first solenoid valve; The first oil port, second oil port, third oil port, and fourth oil port of the first solenoid valve are respectively connected to the excavator end pump oil branch, the excavator end return oil branch, the left turn oil supply line, and the right turn oil supply line; If the vehicle controller receives a left turn signal from the digging end steering control component, the vehicle controller controls the first oil port and the third oil port to connect, and the second oil port and the fourth oil port to connect. If the vehicle controller receives a right turn signal from the digging end steering control component, the vehicle controller controls the first and fourth oil ports to connect, and the second and third oil ports to connect.

3. The system according to claim 1 or 2, characterized in that, The excavator end return oil branch includes a return oil pipeline and a third solenoid valve installed on the return oil pipeline. The vehicle controller controls the opening and closing of the return oil pipeline through the third solenoid valve.

4. The system according to claim 1 or 2, characterized in that, The oil pump branch at the excavator end also includes an oil pump pipeline, a drive unit, and a second solenoid valve. The on-board controller controls the start and stop of the oil pump components through the drive unit; Driven by the drive unit, the oil pumping component pumps hydraulic oil through the oil pumping pipeline to the left turn oil supply circuit or the right turn oil supply circuit; The second solenoid valve is installed on the oil pump line, and the vehicle controller controls the opening and closing of the oil pump line through the second solenoid valve.

5. The system according to claim 4, characterized in that, The excavator end pump oil branch also includes an excavator end steering safety valve. The first oil port of the excavator end steering safety valve is located on the pump oil pipeline between the second solenoid valve and the pump oil component, and the second oil port of the excavator end steering safety valve is connected to the hydraulic oil tank.

6. The system according to claim 1, characterized in that, The system also includes a vehicle speed sensor. If the vehicle controller determines that the vehicle speed sensed by the vehicle speed sensor is less than a threshold, the vehicle controller will then control the connection between the branch circuit and the fuel supply circuit.

7. The system according to claim 6, characterized in that, The system also includes a digging end steering activation switch. If the vehicle controller receives the steering activation signal output by the digging end steering activation switch, the vehicle controller will receive the vehicle speed sensed by the vehicle speed sensor and make a judgment on the vehicle speed.

8. The system according to claim 1, characterized in that, The digging end steering control components are the digging end handle rollers or buttons.

9. A method for controlling the digging end steering of a backhoe loader, characterized in that, The system described in any one of claims 1 to 8 is used for steering, and the method includes: In response to receiving the left turn signal output by the digging end steering control component, the digging end pump oil branch is connected to the left turn oil supply line, the pumping component in the digging end pump oil branch is controlled to pump hydraulic oil to the left turn oil supply line, and the digging end return oil branch is connected to the right turn oil supply line. In response to receiving a right turn signal from the excavator end steering control unit, the system controls the excavator end pump oil branch to connect with the right turn oil supply line, controls the pumping unit in the excavator end pump oil branch to pump hydraulic oil to the right turn oil supply line, and controls the excavator end return oil branch to connect with the left turn oil supply line.

Images