A semi-trailer master, slave steering system

Abstract

This invention discloses a novel semi-trailer driver-follower steering system, comprising a front steering mechanism mounted on the front end of the semi-trailer frame, a hydraulic drive system mounted in the middle section of the semi-trailer frame, a rear steering mechanism mounted at the rear wheels of the semi-trailer, and a steering remote control mounted in the cab of the tractor unit. Both the front and rear steering mechanisms are connected to the hydraulic drive system, which is communicatively connected to the steering remote control. The advantages of this invention include: enabling the rear wheels to follow the tractor unit's steering synchronously, and allowing the rear wheels to independently and actively steer under the control of the remote control; significantly reducing the turning radius of the train; enabling steering in a smaller space; improving vehicle adaptability; reducing tire wear; and improving ride smoothness.

Description

Technical Field

[0001] This invention relates to the field of semi-trailer steering technology, specifically to a semi-trailer master and follow steering system. Background Technology

[0002] Traditional semi-trailers are mostly passively steered, meaning they are forcibly steered by the tractor unit. This type of steering usually has many drawbacks, such as: large tire wear and uneven wear; large turning radius, making it impossible to steer in narrow areas; and poor driving smoothness. Summary of the Invention

[0003] The purpose of this invention is to provide a semi-trailer driver-driven steering system to solve the defects of the traditional passive steering method of semi-trailers in the background art.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A semi-trailer driver-follower steering system includes a front steering mechanism mounted on the front end of the semi-trailer frame, a hydraulic drive system mounted on the middle section of the semi-trailer frame, a rear steering mechanism mounted at the rear wheels of the semi-trailer, and a steering remote control mounted in the cab of the tractor unit. The front and rear steering mechanisms are both connected to the hydraulic drive system, which in turn communicates with the steering remote control. During operation, the front and rear steering mechanisms can both synchronously follow the steering of the tractor unit and independently and actively steer under the control of the steering remote control.

[0006] Furthermore, the front steering mechanism includes an active steering arm, a left active steering cylinder, a right active steering cylinder, an active steering arm shaft, and an active steering arm wedge block;

[0007] The active steering arm is mounted on the semi-trailer frame via an active steering arm shaft and is located above the towing pin. The towing pin is mounted on the lower front end of the semi-trailer frame and is arranged coaxially with the active steering arm shaft.

[0008] The left active steering cylinder and the right active steering cylinder are symmetrically arranged on the left and right sides of the active steering arm, and are both connected to the hydraulic drive system. The large-diameter ends of the left active steering cylinder and the right active steering cylinder are hinged to the semi-trailer frame, and the small-diameter ends are hinged to the front end of the active steering arm.

[0009] The active steering arm wedge block is located at the lower rear end of the active steering arm and is used to be adapted and connected to the wedge of the tractor plate of the tractor vehicle.

[0010] Furthermore, the number of rear steering mechanisms is comparable to the number of rear wheels of the semi-trailer, and each rear steering mechanism is correspondingly arranged between a set of left and right opposite rear wheels of the semi-trailer and is connected to the hydraulic drive system.

[0011] Furthermore, each of the rear steering mechanisms includes a wheel axle, two wheel hinges, two wheel steering levers, a left wheel steering cylinder, and a right wheel steering cylinder;

[0012] The wheel axle is set between a set of left and right opposite semi-trailer rear wheels, and each of its left and right ends is hinged to a set of left and right opposite semi-trailer rear wheels through a wheel hinge axle.

[0013] Both the left and right wheel steering cylinders are located on one side of the wheel axle and are connected to the hydraulic drive system. The large-diameter ends of both cylinders are hinged to the middle of the wheel axle, and the small-diameter ends are each hinged to a corresponding set of left and right rear semi-trailer wheels via a wheel steering lever.

[0014] Furthermore, the hydraulic drive system includes an electric hydraulic pump, a multi-way electromagnetic hydraulic valve group, and a hydraulic oil tank. The electric hydraulic pump is connected to the multi-way electromagnetic hydraulic valve group and the hydraulic oil tank respectively. The multi-way electromagnetic hydraulic valve group is connected to the hydraulic oil tank, the left active steering cylinder and the right active steering cylinder of the front steering mechanism, and the left wheel steering cylinder and the right wheel steering cylinder of each of the rear steering mechanisms respectively.

[0015] Furthermore, the multi-way electromagnetic hydraulic valve group is composed of four two-position two-way electromagnetic hydraulic valves and two three-position four-way electromagnetic hydraulic directional valves.

[0016] The inlet ports of the four two-position two-way electromagnetic hydraulic valves are sequentially connected to the rod chamber and rodless chamber of the left active steering cylinder and the rod chamber and rodless chamber of the right active steering cylinder, and the return ports are all connected to the hydraulic oil tank; among them, the outlet port of the two-position two-way electromagnetic hydraulic valve connected to the rod chamber of the left active steering cylinder is connected to the rod chamber of the right wheel steering cylinder in each rear steering mechanism; the outlet port of the two-position two-way electromagnetic hydraulic valve connected to the rodless chamber of the left active steering cylinder is connected to the rodless chamber of the right wheel steering cylinder in each rear steering mechanism (5); the outlet port of the two-position two-way electromagnetic hydraulic valve connected to the rod chamber of the right active steering cylinder is connected to the rod chamber of the left wheel steering cylinder in each rear steering mechanism; the outlet port of the two-position two-way electromagnetic hydraulic valve connected to the rodless chamber of the right active steering cylinder is connected to the rodless chamber of the left wheel steering cylinder in each rear steering mechanism;

[0017] The left wheel steering cylinder in each of the rear steering mechanisms is also connected to the electro-hydraulic pump and the hydraulic tank via one of the three-position four-way solenoid hydraulic directional valves.

[0018] Each of the right wheel steering cylinders in the rear steering mechanism is also connected to the electric hydraulic pump and the hydraulic oil tank via another three-position four-way solenoid hydraulic directional valve.

[0019] Each of the two-position two-way solenoid hydraulic valves and three-position four-way solenoid hydraulic directional valves is wirelessly connected to the steering remote control.

[0020] Furthermore, each of the two hinge points of the left and right active steering cylinders forms a first dynamic triangle with the active steering arm.

[0021] Each of the two hinge points of the left wheel steering cylinder and the right wheel steering cylinder in the rear steering mechanism forms a second dynamic triangle with the corresponding wheel axle.

[0022] The first dynamic triangle and the second dynamic triangle are similar triangles.

[0023] Compared with the prior art, the advantages of the present invention are: 1) It can both enable the rear wheels to follow the tractor in sync with the front tractor and enable the rear wheels to independently and actively steer under the control of the remote controller; 2) It can significantly reduce the turning radius of the train and enable steering in a smaller space, which can not only improve the adaptability of the vehicle, but also reduce tire wear and improve the smoothness of the vehicle ride. Attached Figure Description

[0024] Figure 1 This is a side view diagram showing the assembly relationship between the semi-trailer driver, the follow-up steering system, and the semi-trailer of the present invention.

[0025] Figure 2 This is a top-view diagram showing the assembly relationship between the semi-trailer driver, the follow-up steering system, and the semi-trailer of the present invention.

[0026] Figure 3 for Figure 1 Enlarged view of a portion of the image;

[0027] Figure 4 This is a schematic diagram of the dynamic triangle formed by the two hinge points of the left active steering cylinder and the active swing arm shaft.

[0028] Figure 5 A schematic diagram of the dynamic triangle formed by the two hinge points of the left wheel steering cylinder and the wheel axle;

[0029] Figure 6 This diagram illustrates the connection principle between the active steering cylinder, the wheel steering cylinder, and the hydraulic drive system.

[0030] Explanation of reference numerals in the attached drawings: 1. Chassis; 2. Traction pin; 3. Rear wheel; 4. Front steering mechanism; 41. Active steering arm; 42. Left active steering cylinder; 43. Right active steering cylinder; 44. Active steering arm shaft; 45. Active steering arm wedge block; 5. Rear steering mechanism; 51. Wheel axle; 52. Wheel hinge shaft; 53. Wheel steering rod; 54. Left wheel steering cylinder; 55. Right wheel steering cylinder; 6. Hydraulic drive system; 61. Electro-hydraulic pump; 62. Multi-way electromagnetic hydraulic valve group; 621. Two-position two-way electromagnetic hydraulic valve; 622. Three-position four-way electromagnetic hydraulic directional valve; 63. Hydraulic oil tank. Detailed Implementation

[0031] To make the technical means, creative features, objectives and effects of this invention easier to understand, the following description, in conjunction with the accompanying drawings and specific embodiments, further explains how this invention is implemented.

[0032] See Figures 1 to 6 The present invention provides a semi-trailer master and follow steering system, comprising a front steering mechanism 4 disposed on the front end of the semi-trailer frame 1, a hydraulic drive system 6 disposed on the middle section of the semi-trailer frame 1, a rear steering mechanism 5 disposed at the rear wheel 3 of the semi-trailer, and a steering remote control disposed in the cab of the tractor. The front steering mechanism 4 and the rear steering mechanism 5 are both connected to the hydraulic drive system 6, and the hydraulic drive system 6 is communicatively connected to the steering remote control. During operation, the front steering mechanism 4 and the rear steering mechanism 5 can both follow the tractor in front and turn synchronously, and can also turn independently under the control of the steering remote control.

[0033] Specifically, in this invention, the aforementioned front steering mechanism 4 includes an active steering arm 41, a left active steering cylinder 42, a right active steering cylinder 43, an active steering arm shaft 44, and an active steering arm wedge block 45. The active steering arm 41 is mounted on the semi-trailer frame 1 via the active steering arm shaft 44 and is located above the towing pin 2. The towing pin 2 is mounted on the lower front end of the semi-trailer frame 1 and is coaxially aligned with the active steering arm shaft 44. The left active steering cylinder 42 and the right active steering cylinder 43 are symmetrically located on the left and right sides of the active steering arm 41 and are both connected to the hydraulic drive system 6. The large-diameter ends of both the left and right active steering cylinders 42 and 43 are hinged to the semi-trailer frame 1, and their small-diameter ends are hinged to the front end of the active steering arm 41. The active steering arm wedge block 45 is located at the lower rear end of the active steering arm 41 and is used to be adapted to connect with the wedge of the tractor's tractor plate.

[0034] Specifically, in this invention, the number of rear steering mechanisms 5 is equivalent to the number of semi-trailer rear wheels 3, and each rear steering mechanism 5 is correspondingly arranged between a set of left and right opposite semi-trailer rear wheels 3 and connected to the hydraulic drive system 6. More specifically, each rear steering mechanism 5 includes a wheel axle 51, two wheel hinge axles 52, two wheel steering levers 53, a left wheel steering cylinder 54, and a right wheel steering cylinder 55; wherein, the wheel axle 51 is arranged between a corresponding set of left and right opposite semi-trailer rear wheels 3, and its left and right ends are each hinged to the corresponding set of left and right opposite semi-trailer rear wheels 3 through a wheel hinge axle 52; the left wheel steering cylinder 54 and the right wheel steering cylinder 55 are both arranged on one side of the wheel axle 51 and are both connected to the hydraulic drive system 6, and the large-diameter ends of the left wheel steering cylinder 54 and the right wheel steering cylinder 55 are hinged to the middle of the wheel axle 51, and the small-diameter ends are each hinged to the corresponding set of left and right opposite semi-trailer rear wheels 3 through a wheel steering lever 53.

[0035] Specifically, in this invention, the hydraulic drive system 6 includes an electro-hydraulic pump 61, a multi-way electromagnetic hydraulic valve group 62, and a hydraulic oil tank 63. The electro-hydraulic pump 61 is connected to the multi-way electromagnetic hydraulic valve group 62 and the hydraulic oil tank 63, respectively. The multi-way electromagnetic hydraulic valve group 62 is connected to the hydraulic oil tank 63, the left active steering cylinder 42 and the right active steering cylinder 43 of the front steering mechanism 4, and the left wheel steering cylinder 54 and the right wheel steering cylinder 55 of each rear steering mechanism 5.

[0036] More specifically, the aforementioned multi-way electromagnetic hydraulic valve group 62 is composed of four two-position two-way electromagnetic hydraulic valves 621 and two three-position four-way electromagnetic hydraulic directional valves 622. The inlet ports of the four two-position two-way electromagnetic hydraulic valves 621 are sequentially connected to the rod-side and rodless-side chambers of the left active steering cylinder 42 and the rod-side and rodless-side chambers of the right active steering cylinder 43. The return ports of all four two-position two-way electromagnetic hydraulic valves 621 are connected to the hydraulic oil tank 63. The outlet port of one two-position two-way electromagnetic hydraulic valve 621 connected to the rod-side chamber of the left active steering cylinder 42 is connected to the rod-side chamber of the right wheel steering cylinder 55 in each rear steering mechanism 5. The outlet port of one two-position two-way electromagnetic hydraulic valve 621 connected to the rodless-side chamber of the left active steering cylinder 42 is connected to the rodless-side chamber of the right wheel steering cylinder 55 in each rear steering mechanism 5. The outlet port of the two-position two-way electromagnetic hydraulic valve 621 connected to the rodless-side chamber of the left active steering cylinder 42 is connected to the rodless-side chamber of the right wheel steering cylinder 55 in each rear steering mechanism 5. The outlet of a two-position two-way solenoid hydraulic valve 621 is connected to the rod chamber of the left wheel steering cylinder 54 in each rear steering mechanism 5; the outlet of a two-position two-way solenoid hydraulic valve 621 connected to the rodless chamber of the right active steering cylinder 43 is connected to the rodless chamber of the left wheel steering cylinder 54 in each rear steering mechanism 5; each left wheel steering cylinder 54 in each rear steering mechanism 5 is also connected to the electric hydraulic pump 61 and the hydraulic oil tank 63 through one three-position four-way solenoid hydraulic directional valve 622; each right wheel steering cylinder 55 in each rear steering mechanism 5 is also connected to the electric hydraulic pump 61 and the hydraulic oil tank 63 through another three-position four-way solenoid hydraulic directional valve 622; and each two-position two-way solenoid hydraulic valve 621 and the three-position four-way solenoid hydraulic directional valve 622 are wirelessly connected to the steering remote controller for operation under the control of the steering remote controller.

[0037] When in use, when the two-position two-way solenoid hydraulic valve 621, which is connected to the rodless chamber of the left active steering cylinder 42, is de-energized, the rodless chamber of the left active steering cylinder 42 is connected to the rodless chamber of the right wheel steering cylinder 55 and disconnected from the hydraulic oil tank 63.

[0038] When the two-position two-way solenoid hydraulic valve 621, which is connected to the rodless chamber of the left active steering cylinder 42, is energized, the rodless chamber of the left active steering cylinder 42 is disconnected from the rodless chamber of the right wheel steering cylinder 55 and connected to the hydraulic oil tank 63.

[0039] When the two-position two-way solenoid hydraulic valve 621, which is connected to the rod chamber of the left active steering cylinder 42, is de-energized, the rod chamber of the left active steering cylinder 42 is connected to the rod chamber of the right wheel steering cylinder 55 and disconnected from the hydraulic oil tank 63.

[0040] When the two-position two-way solenoid hydraulic valve 621, which is connected to the rod chamber of the left active steering cylinder 42, is energized, the rod chamber of the left active steering cylinder 42 is disconnected from the rod chamber of the right wheel steering cylinder 55 and connected to the hydraulic oil tank 63.

[0041] When the two-position two-way solenoid hydraulic valve 621, which is connected to the rodless chamber of the right active steering cylinder 43, is de-energized, the rodless chamber of the right active steering cylinder 43 is connected to the rodless chamber of the left wheel steering cylinder 54 and disconnected from the hydraulic oil tank 63.

[0042] When the two-position two-way solenoid hydraulic valve 621, which is connected to the rodless chamber of the right active steering cylinder 43, is energized, the rodless chamber of the right active steering cylinder 43 is disconnected from the rodless chamber of the left wheel steering cylinder 54 and connected to the hydraulic oil tank 63.

[0043] When the two-position two-way solenoid hydraulic valve 621, which is connected to the rod chamber of the right active steering cylinder 43, is de-energized, the rod chamber of the right active steering cylinder 43 is connected to the rod chamber of the left wheel steering cylinder 54 and disconnected from the hydraulic oil tank 63.

[0044] When the two-position two-way solenoid hydraulic valve 621, which is connected to the rod chamber of the right active steering cylinder 43, is energized, the rod chamber of the right active steering cylinder 43 is disconnected from the rod chamber of the left wheel steering cylinder 54 and connected to the hydraulic oil tank 63.

[0045] When the three-position four-way electromagnetic hydraulic directional valve 622 connected to the left wheel steering cylinder 54 is de-energized, the left wheel steering cylinder 54 is disconnected from the electric hydraulic pump 61 and the hydraulic oil tank 63.

[0046] When the three-position four-way electromagnetic hydraulic directional valve 622, which is connected to the left wheel steering cylinder 54, is energized and reverses to the left, the rod chamber of the left wheel steering cylinder 54 is connected to the electric hydraulic pump 61, and the rodless chamber is connected to the hydraulic oil tank 63.

[0047] When the three-position four-way electromagnetic hydraulic directional valve 622, which is connected to the left wheel steering cylinder 54, is energized and reverses to the right, the rod chamber of the left wheel steering cylinder 54 is connected to the hydraulic oil tank 63, and the rodless chamber is connected to the electric hydraulic pump 61.

[0048] When the three-position four-way electromagnetic hydraulic directional valve 622 connected to the right wheel steering cylinder 55 is de-energized, the right wheel steering cylinder 55 is disconnected from the electric hydraulic pump 61 and the hydraulic oil tank 63.

[0049] When the three-position four-way electromagnetic hydraulic directional valve 622, which is connected to the right wheel steering cylinder 55, is energized and reverses to the left, the rod chamber of the right wheel steering cylinder 55 is connected to the electric hydraulic pump 61, and the rodless chamber is connected to the hydraulic oil tank 63.

[0050] When the three-position four-way electromagnetic hydraulic directional valve 622, which is connected to the right wheel steering cylinder 55, is energized and reverses to the right, the rod chamber of the right wheel steering cylinder 55 is connected to the hydraulic oil tank 63, and the rodless chamber is connected to the electric hydraulic pump 61.

[0051] Specifically, in this invention, the two hinge points of each of the left active steering cylinder 42 and the right active steering cylinder 43 in the aforementioned front steering mechanism 4 each form a first dynamic triangle P with the active steering arm 41; the two hinge points of each of the left wheel steering cylinder 54 and the right wheel steering cylinder 55 in each rear steering mechanism 5 each form a second dynamic triangle Q with the corresponding wheel axle 51; wherein, the first dynamic triangle P and the second dynamic triangle Q are similar triangles at all times. Because these two triangles are similar triangles, it ensures that the turning angle of the semi-trailer's rear wheels is always consistent with the turning angle of the tractor.

[0052] Specifically, in this invention, the left active steering cylinder 42 in the front steering mechanism 4 and the right wheel steering cylinder 55 in the rear steering mechanism 5, and the right active steering cylinder 43 in the front steering mechanism 4 and the left wheel steering cylinder 54 in the rear steering mechanism 5, all satisfy the following relationship:

[0053] Assume: The shortest center distance between the two hinge shafts of the left (or right) active steering cylinder 42 (or 43) is L1, the maximum stroke is S1, the cross-sectional area of ​​the rodless cavity is φ1, and the cross-sectional area of ​​the rod cavity is φ1'; the shortest center distance between the two hinge shafts of the right (or left) wheel steering cylinder 55 (or 54) is L2, the maximum stroke is S2, the cross-sectional area of ​​the rodless cavity is φ2, and the cross-sectional area of ​​the rod cavity is φ2'; the number of wheel axles of the semi-trailer is n; then we have: S1 / L1=S2 / L2; S1*φ1=S2*φ2*n; S1*φ1'=S2*φ2'*n.

[0054] Specifically, under normal conditions, each of the two-position two-way electromagnetic hydraulic valves 621 and the three-position four-way electromagnetic hydraulic directional valves 622 in the multi-way electromagnetic hydraulic valve group 62 are de-energized. At this time, the semi-trailer is in a follow-up steering state, that is, the front steering mechanism 4 and the rear steering mechanism 5 located on the semi-trailer frame 1 follow the tractor in front and turn synchronously.

[0055] When the semi-trailer needs to be actively steered, it is achieved by operating the steering remote control located in the cab of the tractor. Specifically, first, select the desired steering direction (e.g., left or right turn) according to the actual needs. Then, energize the corresponding two-position two-way solenoid hydraulic valve 621 in the multi-way solenoid hydraulic valve group 62 through the steering remote control, so that the corresponding active steering cylinder is disconnected from the wheel steering cylinder and connected to the hydraulic oil tank 63. Subsequently, energize and reverse the corresponding three-position four-way solenoid hydraulic directional valve 622 in the multi-way solenoid hydraulic valve group 62 through the steering remote control. At the same time, start the electric hydraulic pump 61 through the steering remote control, so that the electric hydraulic pump 61 delivers the hydraulic oil in the hydraulic oil tank 63 to the corresponding wheel steering cylinder through the corresponding three-position four-way solenoid hydraulic directional valve 622, driving the wheel steering cylinder to extend or retract, thereby driving the rear wheels 3 of the semi-trailer to make the corresponding active steering action, thus realizing the active steering of the semi-trailer.

[0056] Finally, it should be noted that the above description is only an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A semi-trailer driver-guided steering system, characterized in that: It includes a front steering mechanism (4) installed at the front end of the semi-trailer frame (1), a hydraulic drive system (6) installed in the middle section of the semi-trailer frame (1), a rear steering mechanism (5) installed at the rear wheel (3) of the semi-trailer, and a steering remote control installed in the cab of the tractor; wherein, the front steering mechanism (4) and the rear steering mechanism (5) are both connected to the hydraulic drive system (6), and the hydraulic drive system (6) is communicatively connected to the steering remote control; when working, the front steering mechanism (4) and the rear steering mechanism (5) can both follow the tractor in front and turn synchronously, and can also turn independently under the control of the steering remote control; The front steering mechanism (4) includes an active steering arm (41), a left active steering cylinder (42), a right active steering cylinder (43), an active steering arm shaft (44), and an active steering arm wedge block (45). The active steering arm (41) is mounted on the semi-trailer frame (1) via the active steering arm shaft (44) and is located above the towing pin (2). The towing pin (2) is mounted on the lower front end of the semi-trailer frame (1) and is arranged coaxially with the active steering arm shaft (44). The left active steering cylinder (42) and the right active steering cylinder (43) are symmetrically arranged on the left and right sides of the active steering arm (41) and are both connected to the hydraulic drive system (6). The large diameter ends of the left active steering cylinder (42) and the right active steering cylinder (43) are hinged to the semi-trailer frame (1), and the small diameter ends are hinged to the front end of the active steering arm (41). The active steering arm wedge block (45) is located at the lower rear end of the active steering arm (41) and is used to be adapted to connect with the wedge of the tractor plate of the tractor vehicle. Each of the rear steering mechanisms (5) includes a wheel axle (51), two wheel hinges (52), two wheel steering levers (53), a left wheel steering cylinder (54), and a right wheel steering cylinder (55). The wheel axle (51) is set between a set of left and right opposite semi-trailer rear wheels (3) and each of its left and right ends is hinged to a set of left and right opposite semi-trailer rear wheels (3) through a wheel hinge axle (52). The left wheel steering cylinder (54) and the right wheel steering cylinder (55) are both located on one side of the wheel axle (51) and are both connected to the hydraulic drive system (6). The large diameter ends of the left wheel steering cylinder (54) and the right wheel steering cylinder (55) are both hinged to the middle of the wheel axle (51), and the small diameter ends are each hinged to a set of left and right opposite semi-trailer rear wheels (3) through a wheel steering rocker arm (53). The two hinge points of the left active steering cylinder (42) and the right active steering cylinder (43) each form a first dynamic triangle (P) with the active steering arm (41). Each of the two hinge points of the left wheel steering cylinder (54) and the right wheel steering cylinder (55) in each of the rear steering mechanisms (5) forms a second dynamic triangle (Q) with the corresponding wheel axle (51). The first dynamic triangle (P) and the second dynamic triangle (Q) are similar triangles.

2. The semi-trailer driver-follower steering system according to claim 1, characterized in that: The number of rear steering mechanisms (5) is equivalent to the number of semi-trailer rear wheels (3), and each rear steering mechanism (5) is correspondingly arranged between a set of left and right opposite semi-trailer rear wheels (3) and connected to the hydraulic drive system (6).

3. The semi-trailer driver-follower steering system according to claim 1, characterized in that: The hydraulic drive system (6) includes an electric hydraulic pump (61), a multi-way electromagnetic hydraulic valve group (62), and a hydraulic oil tank (63). The electric hydraulic pump (61) is connected to the multi-way electromagnetic hydraulic valve group (62) and the hydraulic oil tank (63). The multi-way electromagnetic hydraulic valve group (62) is connected to the hydraulic oil tank (63), the left active steering cylinder (42) and the right active steering cylinder (43) of the front steering mechanism (4), and the left wheel steering cylinder (54) and the right wheel steering cylinder (55) of each of the rear steering mechanisms (5).

4. The semi-trailer driver-follower steering system according to claim 3, characterized in that: The multi-way electromagnetic hydraulic valve group (62) is composed of four two-position two-way electromagnetic hydraulic valves (621) and two three-position four-way electromagnetic hydraulic directional valves (622); The inlets of the four two-position two-way solenoid hydraulic valves (621) are sequentially connected to the rod chamber and rodless chamber of the left active steering cylinder (42) and the rod chamber and rodless chamber of the right active steering cylinder (43), respectively, and their return ports are all connected to the hydraulic oil tank (63). Among them, the outlet of one two-position two-way solenoid hydraulic valve (621) connected to the rod chamber of the left active steering cylinder (42) is connected to the rod chamber of the right wheel steering cylinder (55) in each rear steering mechanism (5); and the outlet of one two-position two-way valve connected to the rodless chamber of the left active steering cylinder (42) is connected to the rodless chamber of the right wheel steering cylinder (55). The outlet of the electromagnetic hydraulic valve (621) is connected to the rodless chamber of the right wheel steering cylinder (55) in each rear steering mechanism (5); the outlet of a two-position two-way electromagnetic hydraulic valve (621) connected to the rod chamber of the right active steering cylinder (43) is connected to the rod chamber of the left wheel steering cylinder (54) in each rear steering mechanism (5); the outlet of a two-position two-way electromagnetic hydraulic valve (621) connected to the rodless chamber of the right active steering cylinder (43) is connected to the rodless chamber of the left wheel steering cylinder (54) in each rear steering mechanism (5). The left wheel steering cylinder (54) in each of the rear steering mechanisms (5) is also connected to the electric hydraulic pump (61) and the hydraulic tank (63) through one of the three-position four-way electromagnetic hydraulic directional valves (622); Each of the right wheel steering cylinders (55) in the rear steering mechanism (5) is also connected to the electric hydraulic pump (61) and the hydraulic oil tank (63) via another three-position four-way electromagnetic hydraulic directional valve (622); Each of the two-position two-way solenoid hydraulic valves (621) and three-position four-way solenoid hydraulic directional valves (622) is wirelessly connected to the steering remote control.

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