CN203427872U - Wheeled crane and steering hydraulic control system thereof - Google Patents

Abstract

The utility model discloses a steering hydraulic control system, which comprises a front group wheel steering hydraulic control system and a rear group wheel steering hydraulic control system. The rear group steering hydraulic control system includes a quantitative pump, a steering oil cylinder, and a hydraulic pump and a system connected in parallel. The first control valve and the second control valve between the oil return circuit; the first control valve controls the oil supply to the steering cylinder, and the second control valve controls the pressure build-up of the oil circuit where the steering cylinder is located according to the working state of the first control valve and unloading. The utility model uses the quantitative pump as the power source, and realizes the steering of the rear group of wheels driven by the steering oil cylinder by controlling the first control valve and the second control valve. In addition, the locking oil cylinder and its control unit are omitted. Compared with the prior art, the manufacturing cost and volume of the steering hydraulic control system are significantly reduced, thereby reducing the overall manufacturing cost of the steering hydraulic control system and expanding its scope of application. On this basis, the utility model also discloses a wheeled crane including the steering hydraulic control system.

Description

A wheeled crane and its steering hydraulic control system

technical field

The utility model relates to the technical field of wheeled cranes, in particular to a wheeled crane and its steering hydraulic control system.

Background technique

At present, engineering vehicles use multi-mode steering functions to cope with normal driving on complex road conditions. Now in combination with Figure 1, we will introduce four commonly used steering modes for engineering vehicles, including front group independent steering A, rear group independent steering B, small turning steering C and crab steering D; The steering direction of the group of wheels is opposite to achieve the smallest turning radius. When the crab turns to D, the steering direction of the front group of wheels and the rear group of wheels is the same, so it is named like a crab walking.

The aforementioned four steering modes are controlled and realized by the steering hydraulic control system, and the specific control principle of the steering hydraulic control system is shown in Fig. 2 . The steering of the front and rear wheels is realized by an independent steering hydraulic control system, in which, the front wheel steering is provided with pressure oil by the front gear pump 10', and the steering gear composed of the first control valve group 11' is used to directly control the front steering. The group steering oil cylinder 12' is completed; the rear group steering hydraulic control system is provided with pressure oil by the rear group variable pump 20', and then the second control valve group 21' and the third control valve group 22' are used to control the rear group steering oil cylinder 24' to complete Steering action.

When the steering oil cylinder 24' of the rear group does not participate in the steering, the second control valve group 21' controls the working oil port A and B to have no flow output, and at the same time, by controlling the flow of the N, T, and X working oil ports to use the third control The valve group 22' controls the rear group locking oil cylinder 23', so that the rear group steering oil cylinder 24' is in a locked state; otherwise, when the rear group steering oil cylinder 24' participates in steering, the second control valve group 21' controls N, The T and X working oil ports use the third control valve group 22' to unload the locking oil cylinder, so that the rear steering oil cylinder 24' is in the unlocked state, and at the same time, control the A and B working oil ports to output pressure and flow. Make the rear group steering oil cylinder 24' act, thereby driving the rear group wheels to produce corresponding steering action.

As mentioned above, the power source of the rear steering cylinder 24' in the existing multi-mode steering system adopts a variable displacement pump, and the variable displacement pump automatically adjusts the outlet flow through the variable control element to maintain a constant pressure in the system. However, due to the complex structure and bulky volume of the variable variable pump, the overall manufacturing cost of the steering hydraulic control system is too high, and it cannot meet the needs of occasions where the installation space is small. In order to solve the above problems, the fixed pump can be used to replace the variable pump. However, since the pressure source in the steering hydraulic control system is in a constant driving state, it is obvious that by simply replacing the pressure source, when the rear group of wheels does not participate in steering, it will The problem that the hydraulic control steering system of the rear group cannot be unloaded.

In view of this, those skilled in the art urgently need to find another way to provide a steering hydraulic control system to solve the problems of high cost and limited application range due to installation space of the existing steering hydraulic control system.

Utility model content

In view of the above defects, the core purpose of the present utility model is to provide a steering hydraulic control system to solve the problems of high manufacturing cost and limited scope of application of the existing hydraulic control steering system. On this basis, the utility model also provides a wheeled crane including the steering hydraulic control system.

The steering hydraulic control system provided by the utility model is a steering hydraulic control system, which includes a front wheel steering hydraulic control system and a rear wheel steering hydraulic control system, and the rear wheel steering hydraulic control system includes:

The steering oil cylinder is used to drive the rear group of wheels to turn, and it is characterized in that it also includes:

a quantitative pump to supply oil to said steering cylinder;

The first control valve is arranged between the steering oil cylinder, the quantitative pump and the oil return circuit of the system, and controls the oil supply of the steering oil cylinder to make the steering oil cylinder act or lock;

The second control valve is arranged in parallel with the first control valve, and controls pressure building or unloading of the oil circuit where the steering oil cylinder is located according to the working state of the first control valve.

Preferably, the first control valve is a two-position three-way reversing valve, and is configured such that: the first control valve is in the neutral position, and the second control valve controls the unloading of the oil circuit where the steering cylinder is located; The first control valve is switched to the left or right position, and the second control valve controls the oil circuit where the steering cylinder is located to build pressure.

Preferably, the second directional control valve includes a two-position four-way reversing valve and an on-off valve, the first working oil port of the two-position four-way reversing valve communicates with the system oil return circuit, and the second working oil port of the two-position four-way reversing valve The working oil port communicates with the quantitative pump, the third working oil port and the fourth working oil port are respectively used to communicate with the two working chambers of the auxiliary actuator of the vehicle, and the switch valve is arranged at the fourth working oil port and the vehicle auxiliary actuator, so as to control the conduction or disconnection of the fourth working oil port and the vehicle auxiliary actuator;

The first control valve is in the neutral position, and the two-position four-way reversing valve and the switching valve control the quantitative pump to communicate with the oil return circuit of the system or supply oil to the auxiliary actuator of the vehicle; The first control valve is switched to the left position or the right position, and the two-position four-way reversing valve and the switching valve control the quantitative pump to supply oil to the steering cylinder and/or the vehicle auxiliary actuator.

Preferably, a controller is also included, the signal output end of the controller is connected to the signal receiving ends of the first control valve and the second control valve; The valve and the second control valve issue corresponding control commands.

Preferably, the controller also includes:

a collection unit, to respectively obtain the actual rotation angle values of the front group of wheels and the rear group of wheels relative to the driving direction of the vehicle;

The calculation unit is configured to acquire the corresponding theoretical rotation angle value of the rear group of wheels according to the steering mode of the vehicle and the actual rotation angle value of the front group of wheels.

Preferably, the first control valve is a proportional valve, and the controller adjusts the valve port opening of the first control valve according to the difference between the actual rotation angle value and the theoretical rotation angle value of the rear group of wheels.

The utility model also provides a wheeled crane, which includes a car body, a front group of wheels and a rear group of wheels that drive the car body to move, and a wheel that drives the front group of wheels and/or the rear group of wheels relative to the car body The steering hydraulic control system whose moving direction turns, the steering hydraulic control system is specifically the steering hydraulic control system as described above.

Compared with the content in the background technology, the steering hydraulic control system for vehicles provided by the utility model includes a front wheel steering hydraulic control system and a rear wheel steering hydraulic control system. The rear wheel steering hydraulic control system includes a quantitative pump, The steering cylinder and the first control valve and the second control valve are arranged in parallel between the hydraulic pump and the oil return circuit of the system; wherein, the steering cylinder is supplied with oil by a quantitative pump to drive the rear group of wheels to turn, and the first control valve controls The oil supply to the steering cylinder is to make the steering cylinder act or lock, and the second control valve controls the pressure build-up and unloading of the oil circuit where the steering cylinder is located according to the working state of the first control valve.

The steering hydraulic control system of the rear group wheel steering hydraulic control system provided by this scheme uses the quantitative pump as the power source of the steering cylinder, and realizes the position of the steering cylinder by controlling the switching of different working positions of the first control valve and the second control valve. The pressure building or unloading of the oil circuit, and the action of turning to the oil cylinder after the pressure is built, in addition, the locking oil cylinder and its control unit in the prior art are also omitted. Obviously, compared with the prior art, the manufacturing cost and volume of the rear group steering hydraulic control system in this solution are significantly reduced, thereby reducing the overall manufacturing cost of the steering hydraulic control system and expanding its scope of application.

In a preferred solution of the present utility model, the first control valve is a two-position three-way reversing valve, the second control valve includes a two-position four-way reversing valve and a switching valve, and the first working oil of the two-position four-way reversing valve The port is connected with the oil return circuit of the system, the second working oil port is connected with the hydraulic pump, the third working oil port and the fourth working oil port are respectively used to communicate with the two working chambers of the auxiliary actuator of the vehicle, and the switch valve is set Between the fourth working oil port and the vehicle auxiliary actuator to control the conduction or disconnection of the two-position four-way reversing valve and the vehicle auxiliary actuator;

The first control valve is in the middle position, the two-position four-way reversing valve and the switch valve control the quantitative pump to communicate with the oil return circuit of the system or supply oil to the auxiliary actuators of the vehicle; the first control valve is switched to the left or right position , two-position four-way reversing valve and on-off valve control the quantitative pump to supply oil to the steering cylinder and/or vehicle auxiliary actuators.

In this solution, the second control valve is formed by cleverly combining the two-position two-way reversing valve and the switch valve, and the quantitative pump is used to supply oil to the auxiliary actuators of the vehicle through the second control valve, so that the steering cylinder is in the position of action and/or lock Constant drive quantitative pump in the state can be used to supply oil to the auxiliary actuators of the vehicle to perform effective work. This not only unloads the oil circuit where the steering cylinder is located, but also avoids the direct connection between the quantitative pump and the oil return circuit of the system. Cause energy consumption and oil temperature rise problems. In addition, oil can also be supplied to the steering oil cylinder and the auxiliary actuators of the vehicle at the same time, thereby significantly improving the working efficiency of the steering hydraulic control actuators.

In yet another preferred solution of the present utility model, the hydraulic control steering system further includes a controller, the signal output end of the controller is connected with the signal receiving ends of the first control valve and the second control valve, and the controller sends a signal to the second control valve according to the steering mode of the vehicle. The first control valve and the second control valve issue corresponding control commands. The controller includes an acquisition unit and a calculation unit; wherein the acquisition unit is used to respectively acquire the actual rotation angle values of the front group of wheels and the rear group of wheels relative to the driving direction of the vehicle, and the calculation unit is based on the steering mode of the vehicle and the front group of wheels to obtain the theoretical rotation angle value of the rear group of wheels, and then judge whether the difference between the actual rotation angle value and the theoretical rotation angle value of the rear group of wheels is equal to zero: if not, the controller sends control commands to the first control valve and the second control valve , to make the steering cylinder act; otherwise, the controller does not send a control command signal, and the steering cylinder remains locked.

In addition, the second control valve is specifically a proportional valve, and the controller adjusts the valve opening of the proportional valve in real time according to the actual rotation angle value and the theoretical rotation angle value, and controls the steering speed by controlling the flow of pressure oil flowing into the steering cylinder. Obviously, the setting of the controller not only improves the automatic control level of the steering control system, but also can adjust the rotation angle of the rear group wheels relative to the driving direction in different steering modes according to different working occasions and conditions, so that the rear wheels can A set of steering wheels realizes steering at any angle. In addition, the working efficiency of the steering hydraulic control system and the steering stability of the rear wheels can be improved.

Description of drawings

Figure 1 shows a schematic diagram of four commonly used steering modes for engineering vehicles;

Fig. 2 shows the control schematic diagram of the existing hydraulic control steering system;

Fig. 3 shows the control principle diagram of the specific embodiment of the hydraulic control steering system provided by the utility model;

FIG. 4 shows a control flowchart of the hydraulic steering system shown in FIG. 3 .

Correspondence between reference numerals and component names in Fig. 1 and Fig. 2:

A front group independent steering mode, B rear group independent steering mode, C small turn steering mode, D crab steering mode, 10' front group gear pump, 11' first control valve group, 12' front group steering oil cylinder, 20' Rear group variable pump, 21' second control valve group, 22' third control valve group, 23' rear group locking oil cylinder, 24' rear group steering oil cylinder.

Correspondence between reference numerals and component names in Fig. 3:

20 Gear pump, 21 Steering cylinder, 22 First control valve, 23 Second control valve, 23-1 Two-position four-way solenoid valve, 23-2 On-off valve, 3 Acquisition unit, 4 Vehicle auxiliary actuators.

Detailed ways

The core of the utility model is to provide a steering hydraulic control system for vehicles. By using the quantitative pump and the control valve group that can unload the constant drive quantitative pump when the steering oil cylinder is locked, the steering hydraulic control system is reduced. cost and expand its scope of application. On this basis, the utility model also provides a wheeled crane including a steering hydraulic control system.

Without loss of generality, the specific embodiment of the hydraulic control steering system provided by the utility model will be described by taking control of the steering of a wheeled crane as an example in conjunction with the accompanying drawings. It can be understood that the hydraulic control steering system in this solution can also be used in other vehicles using steering hydraulic control systems. It should be noted that this utility model only optimizes the design of the rear group steering hydraulic control system of the steering hydraulic control system, and the front group steering hydraulic control system has been introduced in the background technical content, so it will not be repeated here.

Please refer to FIG. 3 , which shows a control principle diagram of a specific embodiment of the hydraulic control steering system provided by the present invention.

As shown in Figure 3, the steering hydraulic control system for wheeled cranes provided by this solution includes a front wheel steering hydraulic control system and a rear wheel steering hydraulic control system, and the rear wheel steering hydraulic control system includes a steering cylinder 21. The gear pump 20 and the first control valve 22 and the second control valve 23 arranged in parallel between the steering cylinder 21 and the gear pump 20 and the oil return circuit of the system; wherein, the gear pump 20 supplies oil to the steering cylinder 21 so that It drives the rear group of wheels to turn. The first control valve 22 controls the oil supply of the steering cylinder 21 to make the steering cylinder 21 act or lock. The second control valve 23 controls the oil supply of the steering cylinder 21 according to the working state of the first control valve 22. Road construction or unloading.

Specifically, the first control valve 22 is a three-position four-way proportional valve, and the second control valve 23 includes a two-position four-way electromagnetic reversing valve 23-1 and a switch valve 23-2. Among them, the first working oil port of the two-position four-way solenoid valve reversing 23-1 is connected with the oil return circuit of the system, the second working oil port is connected with the hydraulic pump, and the third working oil port is connected with the fourth working oil port. They are respectively used to communicate with the two working chambers of the auxiliary actuator 4 of the wheeled crane vehicle. The switch valve 23-2 is set at the fourth working oil port of the two-position four-way solenoid valve reversing valve 23-1 and the auxiliary actuator 4 of the vehicle. Between, to control the conduction and disconnection of the fourth working oil port and the auxiliary actuator 4 of the vehicle.

Next, the control process of the above-mentioned rear group steering hydraulic control system provided by this solution will be described in conjunction with FIG. 3 .

When the wheeled crane is normally running or only the front group of wheels participates in steering, the first control valve 22 is in the neutral position, the steering cylinder 21 is locked, and the two-position four-way electromagnetic reversing valve 23-1 and the switching valve 23- 2 Control the gear pump 20 to communicate with the oil return circuit of the system or supply oil to the auxiliary actuator 4 of the vehicle to unload the oil circuit where the steering cylinder 21 is located; when the wheeled crane needs the rear group of wheels to participate in steering, operate the first control valve 22 Switch to the left or right position, the two-position four-way electromagnetic reversing valve 23-1 and the switch valve 23-2 control the gear pump 20 to supply oil to the steering cylinder 21 and/or the vehicle auxiliary actuator 4, so that the oil in the steering cylinder 21 Road construction pressure, the steering cylinder 21 drives the rear group of wheels to rotate clockwise or counterclockwise relative to the driving direction, and the adjustment of the rotating direction can be realized by switching the left and right working positions of the first control valve.

The above-mentioned rear group steering hydraulic control system uses the gear pump 20 as the power source of the steering cylinder 21, and realizes the pressure building of the oil circuit where the steering cylinder 21 is located by controlling the switching of different working positions of the first control valve 22 and the second control valve 23 Or unloading, and the action of turning to the oil cylinder 21 after the pressure is built. In addition, the locking oil cylinder and its control unit in the prior art are also omitted. Obviously, compared with the prior art, the manufacturing cost and volume of the rear group steering hydraulic control system in this solution are significantly reduced, thereby reducing the overall manufacturing cost of the steering hydraulic control system and expanding its scope of application.

Further, this solution uses the second control valve 23 formed by the clever combination of the two-position two-way reversing valve 23-1 and the on-off valve 23-2, and makes the quantitative pump 20 the power supply for the auxiliary actuator 4 of the vehicle through the second control valve 23. Oil, so that when the steering cylinder 21 is in the locked state, the constant drive quantitative pump 20 can be used to supply oil for the auxiliary actuator 4 to perform effective work, which not only unloads the oil circuit where the steering cylinder 21 is located, but also avoids 20 is directly connected with the oil return circuit of the system to cause problems of energy consumption and oil temperature rise, thereby reducing the operating cost of the steering hydraulic control system. Alternatively, oil can also be supplied to the steering oil cylinder 21 and the vehicle auxiliary actuator 4 at the same time, thereby significantly improving the working efficiency of the steering hydraulic control actuator.

It should be noted that in this solution, the second control valve 23 can also be a single on-off valve or relief valve, which can also solve the unloading problem of the oil circuit where the steering cylinder 21 driven by the gear pump 20 is located. In addition, on the basis of meeting the steering function requirements of controlling the rear group of wheels, at least one of the first control valve 22 and the second control valve 23 in this solution can also be manually controlled.

In addition, the steering hydraulic control system in this solution also includes a controller, the signal output end of the controller is connected with the signal receiving ends of the first control valve 22 and the second control valve 23, and the first control valve 22 is sent to the first control valve 22 by judging the steering mode of the vehicle. and the second control valve 23 to send corresponding control commands. The controller includes an acquisition unit 3 and a calculation unit, wherein the acquisition unit 3 respectively acquires the actual rotation angle values of the front group wheels and the rear group wheels relative to the driving direction of the vehicle, and then inputs them to the calculation and comparison unit to obtain the rear group wheels according to the steering mode of the vehicle. Theoretical rotation angle value, and finally judge whether the difference between the actual rotation angle value and the theoretical rotation angle value of the rear group of wheels is zero, and send corresponding control commands to the first control valve 22 and the second control valve 23 according to the judgment result.

Now illustrate the specific control steps of the above-mentioned controller in conjunction with Fig. 4, the specific control steps of the controller include:

S00, determine whether the rear group of wheels participate in steering: if yes, enter step S10; if not, enter step S20;

S10. Obtain the actual rotation angle values of the front group of wheels or the rear group of wheels respectively, calculate the theoretical rotation angle value of the rear group of wheels, and judge whether the difference between the actual rotation angle value and the theoretical rotation angle value of the rear group of wheels is zero: if not, enter step S20; If yes, go to step S30;

S20, controlling the steering oil cylinder 21 to drive the rear group of wheels to rotate relative to the traveling direction.

S30. Control the steering oil cylinder 21 to maintain a locked state.

It should be noted that the difference between the independent rear group and the small turn with the rear group wheels participating in the steering and the crab steering is that the rotation direction of the rear group wheels relative to the driving direction of the vehicle is opposite, and the adjustment of the rotation direction can be adjusted by switching the first The left and right working positions of the control valve 22 can be realized by those skilled in the art through the existing technology, so this article will not describe the control process of each mode one by one. In addition, the acquisition unit 3 in this solution is specifically an angle sensor installed on the front and rear axles. It can be understood that, on the basis of satisfying the function of obtaining the rotation angle of the front and rear wheels relative to the driving direction of the vehicle, the The acquisition unit 3 may also adopt other devices commonly used by those skilled in the art.

Obviously, the setting of the controller not only improves the automatic control level of the steering control system, but also adjusts the rotation angle of the rear group wheels relative to the driving direction in different steering modes according to different working occasions and conditions, so that the rear group steering can The wheels can be turned at any angle.

Further, as mentioned above, the first control valve 22 in this solution is specifically a three-position four-way proportional valve, and step S10 is implemented in real time during the operation of the oil cylinder in step S20, that is, steps S20 and S10 form a closed-loop control. The valve opening of the three-position four-way proportional valve is adjusted by the difference between the actual rotation angle value and the theoretical rotation angle value of the rear group of wheels, and the steering speed is controlled by controlling the flow of pressure oil flowing into the steering cylinder 21, thereby improving the steering hydraulic control. The efficiency of the system and the steering stability of the rear wheels.

In this scheme, the difference between the actual angle of rotation and the theoretical angle of rotation of the rear group of wheels is directly proportional to the variation of the valve opening of the three-position four-way proportional valve, that is, the piston rod of the steering cylinder 21 performs deceleration. Of course, on the basis of satisfying the function of adjusting the steering speed, the difference between the actual rotation angle value and the theoretical rotation angle value of the rear group of wheels in this scheme is inversely proportional to the change in the valve opening of the three-position four-way proportional valve, or other functions relation.

In addition, it should be noted that step S30 may also include judging whether the vehicle auxiliary actuator 4 needs to work: if yes, go to step S31; if not, go to step S32;

S31. Controlling the pressure build-up of the oil circuit where the auxiliary actuator 4 of the vehicle is located;

S32. Control the unloading of the oil circuit where the vehicle auxiliary actuator 4 is located.

It should be emphasized that the quantitative pump in this scheme is specifically a gear pump. Of course, on the basis of satisfying the function of supplying oil to the steering cylinder, this scheme can also use a quantitative pump such as a plunger pump or a vane pump.

In addition to the above-mentioned steering hydraulic control system, the utility model also provides a wheeled crane. The wheeled crane includes a car body, a front set of wheels and a rear set of wheels that drive the car body to move, and a wheel that drives the front set of wheels and/or the rear set of wheels. A steering hydraulic control system in which a set of wheels rotates in opposite directions relative to the running of the vehicle. The steering hydraulic control system is specifically the steering hydraulic control system as described above. It can be understood that the internal functional elements and working principle of the wheeled crane are the same as those of the prior art, and those skilled in the art can fully realize it based on the prior art, so it will not be repeated here.

The above descriptions are only preferred embodiments of the present utility model, and do not constitute a limitation to the protection scope of the present utility model. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present utility model shall be included in the protection scope of the claims of the present utility model.

Claims (8)

1. Turn to a hydraulic control system, comprise front group of wheel steering hydraulic control system and rear group of wheel steering hydraulic control system, described rear group of wheel steering hydraulic control system comprises:

   Steering cylinder (21), for driving rear group of wheel steering, is characterized in that, also comprises:

   Fix-displacement pump (20), with to described steering cylinder (21) fuel feeding;

   The first control cock (22), be arranged between described steering cylinder (21) and described fix-displacement pump (20) and system oil return oil circuit, by controlling the fuel feeding of described steering cylinder (21), so that described steering cylinder (21) action or locking;

   The second control cock (23), is arranged in parallel with described the first control cock (22), according to the mode of operation of described the first control cock (22), controls described steering cylinder (21) place oil circuit and builds pressure or off-load.
2. 2. the hydraulic control system that turns to according to claim 1, it is characterized in that, described the first control cock (22) is two-bit triplet change-over valve, and be configured to: described the first control cock (22) is positioned at meta, described the second control cock (23) is controlled described steering cylinder (21) place oil circuit off-load; Described the first control cock (22) switches to left position or right position, and described the second control cock (23) is controlled described steering cylinder (21) place oil circuit and built pressure.
3. 3. the hydraulic control system that turns to according to claim 2, it is characterized in that, described second direction control cock (23) comprises two position and four-way reversing valves (23-1) and switch valve (23-2), the first actuator port of described two position and four-way reversing valves (23-1) is communicated with described system oil return oil circuit, its second actuator port is communicated with described fix-displacement pump (20), its the 3rd actuator port and the 4th actuator port are respectively used to be communicated with two epitrochoidal chambers of vehicle secondary actuator (4), described switch valve (23-2) is arranged at the arbitrary branch road between described two position and four-way reversing valves (23-1) and described vehicle secondary actuator (4), to control described two position and four-way reversing valves (23-1) and described vehicle secondary actuator (4) conducting or disconnection,

   Described the first control cock (22) is positioned at meta, and described two position and four-way reversing valves (23-1) and described switch valve (23-2) are controlled that described fix-displacement pump (20) is communicated with described system oil return oil circuit or be described vehicle secondary actuator (4) fuel feeding; Described the first control cock (22) switches to left position or right position, and it is described steering cylinder (21) and/or described vehicle secondary actuator (4) fuel feeding that described two position and four-way reversing valves (23-1) and described switch valve (23-2) are controlled described fix-displacement pump.
4. 4. according to the hydraulic control system that turns to described in any one in claims 1 to 3, it is characterized in that, also comprise controller, the signal output part of described controller is connected with the signal receiving end of described the second control cock (23) with described the first control cock (22); Described controller sends corresponding control command according to Vehicular turn pattern to described the first control cock (22) and described the second control cock (23).
5. 5. the hydraulic control system that turns to according to claim 4, is characterized in that, described controller also comprises:

   Collecting unit (3), to obtain respectively described front group of wheel and described rear group of wheel with respect to the actual rotational angle value of vehicle heading;

   Arithmetic element, by the actual rotational angle value of Vehicular turn pattern and described front group of wheel, obtains the corresponding theory corner value of described rear group of wheel.
6. 6. the hydraulic control system that turns to according to claim 5, it is characterized in that, described the first control cock (22) is apportioning valve, and described controller is adjusted the valve port opening of described the first control cock (22) according to the difference of the actual rotational angle value of described rear group of wheel and theoretical corner value.
7. 7. the hydraulic control system that turns to according to claim 6, is characterized in that, described collecting unit (3) is angular transducer.
8. 8. a wheel crane, the front group of wheel and the rear group of wheel that comprise car body, drive described car body to move, and drive described front group of wheel and/or organize afterwards the hydraulic control system that turns to that wheel rotates with respect to the moving direction of described car body, it is characterized in that, described in turn to hydraulic control system to be specially the hydraulic control system that turns to as described in any one in claim 1 to 7.

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