Tractor front wheel steering system and tractor

Abstract

The tractor front wheel steering system comprises a manual steering assembly, an automatic steering assembly and two steering oil cylinders, the steering oil cylinders are double-acting oil cylinders, the manual steering assembly is provided with an oil inlet, an oil return port and two working oil ports, and the automatic steering assembly is provided with an oil outlet. The automatic steering assembly is provided with an oil inlet, an oil return port and two working oil ports, the oil inlet of the manual steering assembly and the oil inlet of the automatic steering assembly are both communicated with an oil supply pipeline, the oil return port of the manual steering assembly and the oil return port of the automatic steering assembly are both communicated with an oil return pipeline, large-cavity oil ports of the two steering oil cylinders are communicated with each other, and large-cavity oil ports of the two steering oil cylinders are communicated with each other. Two working oil ports of the manual steering assembly, two working oil ports of the automatic steering assembly and small cavity oil ports of the two steering oil cylinders are in one-to-one correspondence and are communicated with one another, and the manual steering assembly and the automatic steering assembly are selectively selected to control the two steering oil cylinders to stretch out and draw back, so that the tractor has an automatic driving function and a manual driving function.

Description

Technical Field

[0001] The invention belongs to the field of tractors, and in particular relates to a tractor front wheel steering system and a tractor. Background Art

[0002] With the continuous development of automation technology, intelligent upgrades have also begun to emerge for agricultural machinery. Taking tractors as an example, unmanned tractors have begun to emerge. They have manual driving mode and automatic driving mode. However, the current structure of tractors that are compatible with automatic steering and manual steering is relatively complex and inconvenient to maintain. Summary of the invention

[0003] In order to solve the above technical problems, the object of the present invention is to provide a tractor front wheel steering system which has a simple structure, is compatible with both automatic steering and manual steering modes, and has a modular arrangement.

[0004] In order to achieve the above-mentioned purpose, the technical scheme of the present invention is as follows: a tractor front wheel steering system, comprising a manual steering assembly, an automatic steering assembly, an oil supply pipeline, an oil return pipeline and two steering cylinders, the steering cylinder is a double-acting cylinder, the manual steering assembly has an oil inlet, an oil return port and two working oil ports, the automatic steering assembly has an oil inlet, an oil return port and two working oil ports, the oil inlet of the manual steering assembly and the oil inlet of the automatic steering assembly are both communicated with the oil supply pipeline, the oil return port of the manual steering assembly and the oil return port of the automatic steering assembly are both communicated with the oil return pipeline, the large cavity oil ports of the two steering cylinders are communicated with each other, the two working oil ports of the manual steering assembly, the two working oil ports of the automatic steering assembly and the small cavity oil ports of the two steering cylinders correspond to each other and are communicated with each other, and the manual steering assembly and the automatic steering assembly are selected to control the extension and retraction of the two steering cylinders.

[0005] The beneficial effect of the above technical solution is that the automatic steering assembly can be opened in this way, and the automatic steering assembly automatically intervenes in the control of the two steering cylinders, and both hands can be taken off the steering wheel.

[0006] The automatic steering assembly described in the above technical scheme includes an electrically controlled valve group and a steering valve group, the electrically controlled valve group having a controlled end, an oil inlet, an oil return port and two working oil ports; the steering valve group having an oil inlet, an oil return port, a feedback end, a switching port, two controlled ends and two working oil ports, the oil inlet of the electrically controlled valve group is connected with the switching port of the steering valve group, the oil inlet of the steering valve group constitutes the oil inlet of the automatic steering assembly, the oil return port of the electrically controlled valve group and the oil return port of the steering valve group together constitute the oil return port of the automatic steering assembly, the two working oil ports of the electrically controlled valve group correspond one-to-one to the two controlled ends of the steering valve group and are connected to each other, the feedback end of the steering valve group is linked with the controlled end of the electrically controlled valve group, and the two working oil ports of the steering valve group constitute the two working oil ports of the automatic steering assembly.

[0007] The beneficial effect of the above technical solution is that the electric control valve group and the steering valve group form a control closed loop, and the electric control valve group controls the operating state of the steering valve group to control the two steering cylinders to perform telescopic steering.

[0008] In the above technical solution, the feedback end of the steering valve group and the controlled end of the electric control valve group are linked via a linkage rod.

[0009] The beneficial effects of the above technical solution are: its structure is simple and the steering accuracy of the steering valve group is higher.

[0010] The electrically controlled valve group in the above technical solution includes an electric controller, two one-way valves and four two-position two-way solenoid valves, the four two-position two-way solenoid valves are connected in sequence to form a closed loop, the electric controller is electrically connected to the four two-position two-way solenoid valves, the electric controller has a sensing end, and the sensing end of the electric controller constitutes the controlled end of the electrically controlled valve group, and the connecting point of two adjacent two-position two-way solenoid valves forms a connecting port, wherein two relatively distributed connecting ports constitute two working oil ports of the electrically controlled valve group, and the remaining two connecting ports respectively constitute the oil inlet and oil return port of the electrically controlled valve group, two of the one-way valves are connected in series between the two working oil ports of the electrically controlled valve group, the inlet ends of the two one-way valves face away from each other, and the oil return port of the electrically controlled valve group is connected to the oil outlet ends of the two one-way valves.

[0011] The beneficial effect of the above technical solution is that the four two-position two-way solenoid valves can be flexibly opened and closed in combination to drive the opening and closing state and opening and closing amount of the steering valve group.

[0012] An oil filter is provided at the oil inlet of the electric control valve group in the above technical solution.

[0013] The beneficial effect of the above technical solution is that it can prevent the residue in the hydraulic oil from entering the electric control valve group.

[0014] A second throttle valve is provided at the oil return port of the electric control valve group in the above technical solution.

[0015] The beneficial effect of the above technical solution is that the second throttle valve can hold back the pressure of the electric control valve group.

[0016] The steering valve group described in the above technical solution includes a three-position six-way valve, a two-position six-way valve and a two-position three-way valve;

[0017] The two-position three-way valve has an oil inlet, an oil return port, a working oil port and a pilot oil port;

[0018] The two-position six-way valve has six oil ports and two pilot oil ports, and the six oil ports of the two-position six-way valve are respectively oil port A, oil port B, oil port C, oil port D, oil port E and oil port F; when the two-position six-way valve is in the left position, oil port A is connected to oil port B, oil port C is connected to oil port D, and oil port E is connected to oil port F; when the two-position six-way valve is in the right position, the pilot oil port at the right end of the two-position six-way valve is connected to oil port A, and oil port A constitutes the switching port of the steering valve group;

[0019] The three-position six-way valve has six oil ports and two pilot oil ports, and the six oil ports of the three-position six-way valve are respectively oil port G, oil port H, oil port I, oil port J, oil port K and oil port L; when the three-position six-way valve is in the left position, oil port G, oil port I and oil port J are connected, and oil port H and oil port K are connected; when the three-position six-way valve is in the middle position, oil port I, oil port K and oil port L are connected; when the three-position six-way valve is in the right position, oil port H, oil port J and oil port L are connected, and oil port G and oil port K are connected, and the valve core of the three-position six-way valve constitutes the feedback end of the steering valve group;

[0020] The pilot oil port of the two-position three-way valve is connected with its oil return port, the working oil port of the two-position three-way valve is connected with the pilot oil port at the left end of the two-position six-way valve, oil port G is connected with oil port C, oil port H is connected with oil port F, oil port D and oil port E constitute the two working oil ports of the steering valve group, oil port I, oil port K, oil port L, the pilot oil port at the right end of the two-position six-way valve and the oil return port of the two-position three-way valve together constitute the oil return port of the steering valve group, and the oil inlet of the two-position three-way valve, oil port B and oil port J together constitute the oil inlet of the steering valve group.

[0021] The beneficial effect of the above technical solution is that the two-position six-way valve is opened or closed under the control of the two-position three-way valve, and when the two-position six-way valve is in the open state, the flow at the oil port C and the oil port E is controlled by the three-position six-way valve, so that the steering amount can be accurately controlled.

[0022] The steering valve group in the above technical solution also includes a pressure reducing valve, and the oil port B and the oil inlet of the two-position three-way valve merge and are connected to the oil supply pipeline through the pressure reducing valve at the confluence.

[0023] The beneficial effect of the above technical solution is that the oil pressure at the oil inlet of the two-position three-way valve and the oil port B of the two-position six-way valve can be reduced in pressure. The hydraulic oil at the oil inlet and oil port B of the two-position three-way valve are both control oil circuits, which do not require higher hydraulic pressure to avoid excessive oil pressure.

[0024] The two-position three-way valve described in the above technical solution is a two-position three-way solenoid valve.

[0025] The beneficial effect of the above technical solution is that it makes it easy to open and close, and can be electrically operated.

[0026] A second object of the present invention is to provide a tractor which is highly intelligent and can be driven both manually and automatically.

[0027] In order to achieve the above object, the technical solution of the present invention is as follows: a tractor comprises the tractor front wheel steering system as described above.

[0028] The beneficial effects of the above technical solution are: it has a simple structure and a high degree of intelligence, and it can flexibly switch between a manual steering mode and an automatic steering mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic structural diagram of a tractor front wheel steering system according to an embodiment of the present invention;

[0030] Figure 2 It is a schematic diagram of the connection between the automatic steering assembly and two steering cylinders in an embodiment of the present invention;

[0031] Figure 3 is a structural schematic diagram of the automatic steering assembly described in an embodiment of the present invention;

[0032] Figure 4 Schematic diagram of the structure of the electric control valve group in an embodiment of the present invention;

[0033] Figure 5 It is a structural schematic diagram of the steering valve group described in an embodiment of the present invention;

[0034] Figure 6 Schematic diagram of the structure of the three-position six-way valve and the two-position six-way valve described in the embodiment of the present invention.

[0035] In the figure: 1. manual steering assembly; 2. automatic steering assembly; 21. electric control valve group; 211. electric controller; 212. one-way valve; 213. two-position two-way solenoid valve; 214. oil filter; 215. second throttle valve; 22. steering valve group; 221. three-position six-way valve; 222. two-position six-way valve; 223. two-position three-way valve; 224. pressure reducing valve; 23. linkage rod; 3. oil supply pipeline; 4. oil return pipeline; 5. steering cylinder. DETAILED DESCRIPTION

[0036] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention. The present invention is described in more detail by way of example with reference to the accompanying drawings in the following paragraphs. The advantages and features of the present invention will become clearer according to the following description and claims. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0037] Example 1

[0038] like Figure 1 As shown, this embodiment provides a tractor front wheel steering system, including a manual steering assembly 1, an automatic steering assembly 2, an oil supply pipeline 3, an oil return pipeline 4 and two steering cylinders 5, wherein the steering cylinder 5 is a double-acting cylinder, the manual steering assembly 1 has an oil inlet, an oil return port and two working oil ports, the automatic steering assembly 2 has an oil inlet, an oil return port and two working oil ports, the oil inlet of the manual steering assembly 1 and the oil inlet of the automatic steering assembly 2 are both connected to the oil supply pipeline 3, the oil return port of the manual steering assembly 1 and the automatic steering assembly 2 are connected to the oil return port of the manual steering assembly 1 and the automatic steering assembly 2. The oil return ports of the steering assembly 2 are all connected to the oil return pipeline 4, the large-cavity oil ports of the two steering cylinders 5 are connected to each other, the two working oil ports of the manual steering assembly 1, the two working oil ports of the automatic steering assembly 2 and the small-cavity oil ports of the two steering cylinders 5 correspond to each other and are connected to each other. The manual steering assembly 1 and the automatic steering assembly 2 are selected to control the extension and retraction of the two steering cylinders 5, so that the automatic steering assembly can be opened. At this time, the automatic steering assembly automatically intervenes in the control of the two steering cylinders, and both hands can be removed from the steering wheel.

[0039] like Figure 2 and Figure 3As shown, the automatic steering assembly 2 in the above technical solution includes an electric control valve group 21 and a steering valve group 22, wherein the electric control valve group 21 has a controlled end, an oil inlet, an oil return port and two working oil ports; the steering valve group 22 has an oil inlet, an oil return port, a feedback end, a switching port, two controlled ends and two working oil ports, the oil inlet of the electric control valve group 21 is connected to the switching port of the steering valve group 22, the oil inlet of the steering valve group 22 constitutes the oil inlet of the automatic steering assembly 2, the oil return port of the electric control valve group 21 and the steering valve group 2 The oil return ports of the electric control valve group 21 and the steering valve group 22 together constitute the oil return port of the automatic steering assembly 2. The two working oil ports of the electric control valve group 21 correspond one to one with the two controlled ends of the steering valve group 22 and are connected to each other. The feedback end of the steering valve group 22 is linked with the controlled end of the electric control valve group 21. The two working oil ports of the steering valve group 22 constitute the two working oil ports of the automatic steering assembly 2. In this way, the electric control valve group and the steering valve group form a control closed loop, and the electric control valve group controls the operating state of the steering valve group to control the two steering cylinders to perform telescopic steering.

[0040] In the above technical solution, the feedback end of the steering valve group 22 and the controlled end of the electric control valve group 21 are linked via a linkage rod 23, which has a simple structure and makes the steering accuracy of the steering valve group higher.

[0041] like Figure 4 As shown, the electric control valve group 21 in the above technical solution includes an electric controller 211, two one-way valves 212 and four two-position two-way solenoid valves 213, and the four two-position two-way solenoid valves 213 are sequentially connected to form a closed loop. The electric controller 211 is electrically connected to the four two-position two-way solenoid valves 213, and the electric controller 211 has a sensing end, and the sensing end of the electric controller 211 constitutes the controlled end of the electric control valve group 21, and the connecting point of two adjacent two-position two-way solenoid valves 213 forms a connecting port, wherein two relatively distributed The connecting port constitutes the two working oil ports of the electric control valve group 21, and the remaining two connecting ports respectively constitute the oil inlet and oil return port of the electric control valve group 21, and two one-way valves 212 are connected in series between the two working oil ports of the electric control valve group 21, the inlet ends of the two one-way valves 212 are away from each other, and the oil return port of the electric control valve group 21 is connected to the oil outlet ends of the two one-way valves 212, so that the four two-position two-way solenoid valves can be flexibly opened and closed to drive the opening and closing state and opening and closing amount of the steering valve group.

[0042] In the above technical solution, an oil filter 214 is provided at the oil inlet of the electric control valve group 21, so as to prevent the residue in the hydraulic oil from entering the electric control valve group.

[0043] In the above technical solution, a second throttle valve 215 is provided at the oil return port of the electric control valve group 21, so that the second throttle valve can hold back the pressure of the electric control valve group.

[0044] like Figure 5 and Figure 6 As shown, the steering valve group 22 in the above technical solution includes a three-position six-way valve 221, a two-position six-way valve 222 and a two-position three-way valve 223;

[0045] The two-position three-way valve 223 has an oil inlet, an oil return port, a working oil port and a pilot oil port;

[0046] The two-position six-way valve 222 has six oil ports and two pilot oil ports. The six oil ports of the two-position six-way valve 222 are respectively oil port A, oil port B, oil port C, oil port D, oil port E and oil port F. When the two-position six-way valve 222 is in the left position, oil port A is connected to oil port B, oil port C is connected to oil port D, and oil port E is connected to oil port F. When the two-position six-way valve 222 is in the right position, the pilot oil port at the right end of the two-position six-way valve 222 is connected to oil port A, and oil port A constitutes the switching port of the steering valve group 22.

[0047] The three-position six-way valve 221 has six oil ports and two pilot oil ports. The six oil ports of the three-position six-way valve 221 are respectively oil port G, oil port H, oil port I, oil port J, oil port K and oil port L; when the three-position six-way valve 221 is in the left position, the oil ports G, oil port I and oil port J are connected, and the oil ports H and oil port K are connected; when the three-position six-way valve 221 is in the middle position, the oil ports I, oil port K and oil port L are connected; when the three-position six-way valve 221 is in the right position, the oil ports H, oil port J and oil port L are connected, and the oil ports G and oil port K are connected. The valve core of the three-position six-way valve 221 constitutes the feedback end of the steering valve group 22;

[0048] The pilot oil port of the two-position three-way valve 223 is connected with its oil return port, the working oil port of the two-position three-way valve 223 is connected with the pilot oil port at the left end of the two-position six-way valve 222, the oil port G is connected with the oil port C, the oil port H is connected with the oil port F, the oil port D and the oil port E constitute the two working oil ports of the steering valve group 22, the oil port I, the oil port K, the oil port L, the pilot oil port at the right end of the two-position six-way valve 222 and the oil return port of the two-position three-way valve 223 together constitute the oil return port of the steering valve group 22, the oil inlet, the oil port B and the oil port J of the two-position three-way valve 223 together constitute the oil inlet of the steering valve group 22, so that the two-position six-way valve is opened or closed under the control of the two-position three-way valve, and when the two-position six-way valve is in the open state, the flow at its oil port C and oil port E is controlled by the three-position six-way valve, so that the steering amount can be accurately controlled.

[0049] The steering valve group 22 in the above technical solution also includes a pressure reducing valve 224. The oil port B and the oil inlet of the two-position three-way valve 223 merge and are connected to the oil supply pipeline 3 through the pressure reducing valve 224 at the confluence, so that the oil pressure of the oil inlet of the two-position three-way valve and the oil port B of the two-position six-way valve can be reduced in pressure. The hydraulic oil at the oil inlet and oil port B of the two-position three-way valve are both control oil circuits, which do not require higher hydraulic pressure to avoid excessive oil pressure.

[0050] The two-position three-way valve 223 in the above technical solution is a two-position three-way solenoid valve, which makes it easy to open and close and can be electrically operated.

[0051] The manual steering assembly 1 described in this embodiment is the prior art, which has a steering wheel and a steering pump, etc. The two-position three-way valve described in this embodiment is a switching valve between the entire automatic steering mode and the manual steering mode. When in the automatic steering mode, both hands need to be off the steering wheel.

[0052] Example 2

[0053] This embodiment provides a tractor, including the tractor front wheel steering system as described in Embodiment 1, which has a simple structure and a high degree of intelligence, and can flexibly switch between a manual steering mode and an automatic steering mode.

[0054] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in the industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with the profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A tractor front wheel steering system, characterized in that: The invention comprises a manual steering assembly (1), an automatic steering assembly (2), an oil supply pipeline (3), an oil return pipeline (4) and two steering oil cylinders (5), wherein the steering oil cylinders (5) are double-acting oil cylinders, the manual steering assembly (1) has an oil inlet, an oil return pipeline and two working oil ports, the automatic steering assembly (2) has an oil inlet, an oil return pipeline and two working oil ports, the oil inlet of the manual steering assembly (1) and the oil inlet of the automatic steering assembly (2) are both connected to the oil supply pipeline (3), and the manual steering assembly (1) is connected to the oil return pipeline (4). The oil return port of the manual steering assembly (1) and the oil return port of the automatic steering assembly (2) are both connected to the oil return pipeline (4), the large-cavity oil ports of the two steering oil cylinders (5) are connected to each other, the two working oil ports of the manual steering assembly (1), the two working oil ports of the automatic steering assembly (2) and the small-cavity oil ports of the two steering oil cylinders (5) correspond to each other and are connected to each other, and the manual steering assembly (1) and the automatic steering assembly (2) are selected to control the extension and retraction of the two steering oil cylinders (5).

2. The tractor front wheel steering system according to claim 1, characterized in that: The automatic steering assembly (2) comprises an electric control valve group (21) and a steering valve group (22); the electric control valve group (21) has a controlled end, an oil inlet, an oil return port and two working oil ports; the steering valve group (22) has an oil inlet, an oil return port, a feedback end, a switching port, two controlled ends and two working oil ports; the oil inlet of the electric control valve group (21) is connected to the switching port of the steering valve group (22); the oil inlet of the steering valve group (22) constitutes the oil inlet of the automatic steering assembly (2). The oil return port of the electric control valve group (21) and the oil return port of the steering valve group (22) together constitute the oil return port of the automatic steering assembly (2); the two working oil ports of the electric control valve group (21) correspond to the two controlled ends of the steering valve group (22) one by one and are connected to each other; the feedback end of the steering valve group (22) is linked to the controlled end of the electric control valve group (21); and the two working oil ports of the steering valve group (22) constitute the two working oil ports of the automatic steering assembly (2).

3. The tractor front wheel steering system according to claim 2, characterized in that: The feedback end of the steering valve group (22) and the controlled end of the electric control valve group (21) are linked via a linkage rod (23).

4. The tractor front wheel steering system according to claim 2, characterized in that: The electric control valve group (21) comprises an electric controller (211), two one-way valves (212) and four two-position two-way solenoid valves (213). The four two-position two-way solenoid valves (213) are sequentially connected to form a closed loop. The electric controller (211) is electrically connected to the four two-position two-way solenoid valves (213). The electric controller (211) has a sensing end, and the sensing end of the electric controller (211) constitutes the controlled end of the electric control valve group (21). The sensing ends of two adjacent two-position two-way solenoid valves (213) are connected to each other in a closed loop. A connection port is formed at the connection point, wherein two relatively distributed connection ports constitute two working oil ports of the electric control valve group (21), and the remaining two connection ports respectively constitute the oil inlet and oil return port of the electric control valve group (21), two one-way valves (212) are connected in series between the two working oil ports of the electric control valve group (21), the inlet ends of the two one-way valves (212) are mutually opposed, and the oil return port of the electric control valve group (21) is connected to the oil outlet ends of the two one-way valves (212).

5. The tractor front wheel steering system according to any one of claims 2 to 4, characterized in that: An oil filter (214) is provided at the oil inlet of the electric control valve group (21).

6. The tractor front wheel steering system according to any one of claims 2 to 4, characterized in that: A second throttle valve (215) is provided at the oil return port of the electric control valve group (21).

7. The tractor front wheel steering system according to any one of claims 2 to 4, characterized in that: The steering valve group (22) comprises a three-position six-way valve (221), a two-position six-way valve (222) and a two-position three-way valve (223); The two-position three-way valve (223) has an oil inlet, an oil return port, a working oil port and a pilot oil port; The two-position six-way valve (222) has six oil ports and two pilot oil ports. The six oil ports of the two-position six-way valve (222) are respectively oil port A, oil port B, oil port C, oil port D, oil port E and oil port F. When the two-position six-way valve (222) is in the left position, oil port A is connected to oil port B, oil port C is connected to oil port D, and oil port E is connected to oil port F. When the two-position six-way valve (222) is in the right position, the pilot oil port at the right end of the two-position six-way valve (222) is connected to oil port A, and oil port A constitutes a switching port of the steering valve group (22); The three-position six-way valve (221) has six oil ports and two pilot oil ports. The six oil ports of the three-position six-way valve (221) are respectively oil port G, oil port H, oil port I, oil port J, oil port K and oil port L. When the three-position six-way valve (221) is in the left position, the oil ports G, oil port I and oil port J are connected, and the oil ports H and oil port K are connected. When the three-position six-way valve (221) is in the middle position, the oil ports I, oil port K and oil port L are connected. When the three-position six-way valve (221) is in the right position, the oil ports H, oil port J and oil port L are connected, and the oil ports G and oil port K are connected. The valve core of the three-position six-way valve (221) constitutes the feedback end of the steering valve group (22). The pilot oil port of the two-position three-way valve (223) is connected to its oil return port, the working oil port of the two-position three-way valve (223) is connected to the pilot oil port at the left end of the two-position six-way valve (222), the oil port G is connected to the oil port C, the oil port H is connected to the oil port F, the oil port D and the oil port E constitute the two working oil ports of the steering valve group (22), the oil port I, the oil port K, the oil port L, the pilot oil port at the right end of the two-position six-way valve (222) and the oil return port of the two-position three-way valve (223) together constitute the oil return port of the steering valve group (22), and the oil inlet of the two-position three-way valve (223), the oil port B and the oil port J together constitute the oil inlet of the steering valve group (22).

8. The tractor front wheel steering system according to claim 7, characterized in that: The steering valve group (22) further comprises a pressure reducing valve (224); the oil port B and the oil inlet of the two-position three-way valve (223) merge and are connected to the oil supply pipeline (3) through the pressure reducing valve (224) at the confluence.

9. The tractor front wheel steering system according to claim 7, characterized in that: The two-position three-way valve (223) is a two-position three-way solenoid valve.

10. A tractor, characterized in that: The invention comprises a tractor front wheel steering system as claimed in any one of claims 1 to 9.

Images