Improved control for wheel excavator

Abstract

A wheel excavator 10 comprising an undercarriage 16, a superstructure 14 fastened to the undercarriage in a rotatable manner, a working device 20 comprising an implement, an electronic control system,

Description

Technical Field

[0001] The present invention pertains to control of wheel excavators, particularly for safe control of wheel excavators travelling on public streets. Technological Background

[0002] Wheel excavators are excavators that are generally configured for moving using wheel axles, in contrast to tracked excavators. Wheel excavators typically comprise two wheel axles and are typically configured for also travelling on public roads. Wheel excavators are also referred to as mobile excavators.

[0003] For moving the wheel axles as well as a working device of the excavator, wheel excavators comprise a hydrostatic drive which is connected to a hydrostatic system of the excavator. The hydrostatic system also provides hydraulic oil to other components of the excavator, such as a pilot hydraulic system and one or more working devices. The hydrostatic system comprise at least one hydraulic pump and a plurality of hydraulic motors. The at least one hydraulic pump is powered by a power source, such as an internal combustion engine.

[0004] Wheel excavators usually comprise an undercarriage and a superstructure that is connected to the undercarriage in a rotatable manner. The connection may, for example, be achieved by means of a rotary joint, such as, for example, a swivel. Further, wheel excavators comprise an operator station, which is typically arranged at the superstructure and comprises an operator interface for operating the excavator, e.g., a steering wheel, a display and a device to control the working device of the excavator.

[0005] Currently, to travel on public roads, by law, many countries require wheel excavators to inhibit a rotatory movement of the wheel excavator’s undercarriage with respect to the superstructure (“swing”), as well as an inhibition of actuation of the excavator’s working device. In countries where functional safety requirements apply, inhibition of the swing and the actuation of the working device must comply with the corresponding functional safety requirements. For travel on public roads, typically, a high level of functional safety is required.

[0006] It is known from the prior art to swing the superstructure to a desired angular position with respect to the undercarriage and to rotatably fix the superstructure with respect to the undercarriage by means of bolts, pins or other locking elements which engage groves or bores. However, this solution does not provide for safe inhibition of actuation of the working device. Also, the solution requires additional mechanical pieces that engage with each other.

[0007] Further, WO 2014 / 186200 discloses a mobile excavator in which an electronic control unit detects, by means of an angle detecting device, position of the superstructure with respect to the undercarriage and engages a locking device upon instruction by the driver if the detected angle lies within a predetermined range. However, as the inhibition of the rotation is effectively software-controlled, the software must satisfy the function safety requirements at a level prescribed for road travel. Thus, a complex software and controller structure is may be necessary.

[0008] US10,442,442B2 discloses a periphery monitoring system including an operation instruction output unit which outputs an operation instruction to a warning device provided in a work vehicle based on detection data of an object detection device detecting an object in a periphery of the work vehicle, an invalidating unit which invalidates the operation instruction based on an invalidating instruction output from a cancel operation device provided in a driving room of the work vehicle, and a validating unit which validates the invalidated operation instruction based on detection data of a boarding state detection device detecting a specific boarding state of a passenger in the driving room.

[0009] US2023 / 0064337A1 discloses technique directed to methods and systems of an implement lock-out on lever-controlled machines. A lock-out system can monitor the position of an implement and lock-out the implement control(s) when the implement is within a threshold distance to parts of the machine. The lock-out system can generate an implement lock-out to slow, stop, or reduce the force of a hydraulic valve(s) controlling the implement. The lockout system can use inputs such as electronic fence blade position system data, articulation angles, wheel lean angles, steering angles, ripper positions, mode selection or similar data to determine to generate the implement lock-out. The lock-out system can generate the implement lock-out by a flow supply shutoff to the implement while maintaining pressure to the steering valve. The lock-out system can send visual or audible notifications to alert the operator of the implement's proximity to the machine or of an implement lock-out.

[0010] US7,334,658B2 discloses a steering system provided for a work machine. The steering system may include at least one hand-operated work implement control device and a steering mechanism configured to control a direction of travel of the work machine. The system may also include a first steering device operatively coupled to the steering mechanism and configured to control at least one component of the steering mechanism based on operator input. The system may further include a second steering device mounted on the work implement control device. The second steering device may be configured to be selectively operatively coupled to the steering mechanism to thereby control a direction of travel of the work machine based on lateral movement of the second steering device relative to the work implement control device. Summary of the invention

[0011] It is an object of the present invention to overcome or at least alleviate the shortcomings of the prior art.

[0012] In particular, it is an object of the present invention to provide a wheel excavator configured for safe inhibition of rotation of a superstructure with respect to an undercarriage and operation of the working device for transfer on public roads.

[0013] It is an optional object of the present invention to provide such wheel excavator with safe inhibition of rotation and working device operation comprising a simplified system design with respect to the prior art.

[0014] This objective is solved by means of a wheel excavator with the features of claim 1 and a method with the features of claim 10. Preferred embodiments are set forth in the present specification, the Figures as well as the dependent claims.

[0015] According to another aspect of the present disclosure, a wheel excavator may comprise an undercarriage, a superstructure fastened to the undercarriage in a rotatable manner, a working device for receiving at least one implement, an electronic control system, a locking device configured for rotatably fixing the superstructure with respect to the undercarriage in a releasable manner and a switch unit. The wheel excavator may further comprise a hydrostatic system configured for operating the working device and the locking device. The hydrostatic system may comprise a first electromagnetic valve configured for providing hydraulic supply to the locking device, the first electromagnetic valve comprising a first solenoid, and a second electromagnetic valve configured for pilot hydraulic supply for operating the working device, the second electromagnetic valve comprising a second solenoid. The switch unit may comprise at least a first switch position, in which the switch unit is configured for connecting each of the first solenoid and the second solenoid to the electronic control system, and a second switch position, in which the switch unit is configured for disconnecting each of the first solenoid and the second solenoid from the electronic control system.

[0016] According to another aspect of the present disclosure, a method for locking a superstructure that is fastened to an undercarriage of a wheel excavator in a rotatable manner is disclosed. The wheel excavator may further comprise a working device for receiving at least one implement, an electronic control system, a locking device, a switch unit configured for being operated by a driver and a hydrostatic system. The hydrostatic system may comprise a first electromagnetic valve arranged to provide hydraulic supply to the locking device, the first electromagnetic valve comprising a first solenoid, and a second electromagnetic valve arranged for pilot hydraulic supply for operating the working device, the second electromagnetic valve comprising a second solenoid. The method may further comprise a first step comprising actuating the switch unit to assume a first switch position, thus connecting each of the first solenoid and the second solenoid to the electronic control system by means of the switch unit, enabling pilot hydraulic supply for operating the working device and enabling hydraulic supply to the locking device. The method may also comprise a second step comprising actuating the switch unit to assume a second switch position, thus disconnecting each of the first solenoid and the second solenoid from the electronic control system by means of the switch unit, stopping pilot hydraulic supply for operating the working device and stopping hydraulic supply to the locking device. Brief description of the drawings

[0017] The present disclosure will be more readily appreciated by reference to the following detailed description when being considered in connection with the accompanying drawings in which:

[0018] Figure 1 shows a schematic view of a wheel excavator;

[0019] Figure 2 shows a view of the wheel excavator from above;

[0020] Figure 3 a shows a schematic control diagram according to one embodiment;

[0021] Figure 3b shows an embodiment of a switch unit;

[0022] Figure 4 shows a schematic control diagram according to another embodiment;

[0023] Figure 5 a shows a flowchart of an embodiment of a method;

[0024] Figure 5b shows a flowchart of another embodiment of the method;

[0025] Figure 6a shows a schematic control diagram according to a further embodiment; and

[0026] Figure 6b shows a schematic control diagram according to still another embodiment. Detailed description of preferred embodiments

[0027] In the following, the invention will be explained in more detail with reference to the accompanying figures. In the Figures, like elements are denoted by identical reference numerals and repeated description thereof may be omitted in order to avoid redundancies.

[0028] Fig. 1 shows an illustration of a wheel excavator 10. The wheel excavator of Fig. 1 comprises a power source, such as an internal combustion engine 12. The power source is configured for providing mechanical power, inter alia, to a hydrostatic system of the wheel excavator 10. The hydrostatic system also provides hydraulic oil to components of the wheel excavator 10, such as a pilot hydraulic system and a working device 20, which will be discussed in more detail below. The hydrostatic system comprise at least one hydraulic pump and a plurality of hydraulic motors. For improved intelligibility, the hydrostatic system is not shown in Fig. 1.

[0029] The wheel excavator 10 comprises an undercarriage 16 and a superstructure 14 fastened to the undercarriage in a rotatable manner. That is, the superstructure 14 can be rotated with respect to the undercarriage 16. This fastening can be implemented, e.g., by means of a rotary joint or a swivel.

[0030] Further, the wheel excavator 10 comprises a traction system 18. The traction system is, in the example of Fig. 1, disposed at the undercarriage. The traction system 18 is configured for propelling the wheel excavator 10. The traction system 18 comprises a first axle comprising a first set of wheels 24 and a second axle comprising a second set of wheels 26. One or both axles may be steerable. In the example of Fig. 1, the wheel excavator 10 is an all-wheel-drive mobile excavator 10, thus, both sets of wheels 24, 26 can be driven. The traction system may be powered by the hydrostatic system. In particular, the traction system may comprise one or more hydraulic motors connected to the hydrostatic system.

[0031] The wheel excavator 10 comprises an operator station 22 disposed at the superstructure 14. The wheel excavator 10 of Fig. 1 also comprises a working device 20. The working device 20 comprises a boom 28 rotatably fixed to the superstructure 14, a stick 30, and an implement 32 disposed at an end of the stick. In order to move the boom 28, the wheel excavator comprises a boom actuator 34. In the example of Fig. 1, the boom actuator 34 is a hydraulic cylinder. Thus, a distal end of the boom 36 can be raised and lowered. The distal end of the boom 36 may, for example, be distal to the superstructure 14. Thus, a movement comprising a vertical component can be performed. Further, by rotation of the superstructure 14 with respect to the undercarriage 16 about a vertical axis 38, a movement in a horizontal plane can be performed. The boom actuator 34 may, for example, be controlled by means of a stick actuator 44 arranged at the operator station 22.

[0032] The working device 20 further comprises a stick 30. A proximal end of the stick 42 may be joined to the distal end of the boom 36. By means of a stick actuator 44, which may also be a hydraulic cylinder, a distal end of the stick 46 may be moved with respect to the boom 28. Thus, a translational movement of the implement 32 mounted to the distal end of the stick 46 may be achieved. The implement 32 is mounted to the distal end of the stick 46 in a rotatable manner.

[0033] The implement 32 may be any type of implement, such as a bucket 48, pincers, brushes or the like. In other words, the implement 32 can be any type of working tool suitable for the mobile excavator 10.

[0034] For rotating the implement 32, the wheel excavator 10 further comprises a working tool actuator 50 mounted at the stick 30. In the example of Fig. 1, the working tool actuator 50 is a hydraulic cylinder. By extending and retracting the working tool actuator 50, the implement can be rotated about the distal end of the stick 46.

[0035] The operator station 22 may, for example, be arranged in an operator’s cab. The operator station 22 in Fig 1 comprises a seat 52, a steering wheel 54, a display 55 for output of information, and a working device control device 56. The working device control device 56 may, for example, comprise a joystick or another interface element.

[0036] The operator station 22 in Fig. 1 enables control of the working device 20 and the traction system 18 by means of an electronic control system 64. The electronic control system 64 receives commands from the operator and controls the hydrostatic system accordingly, e.g., by actuation of electromagnetic valves for pilot hydraulic supply or electromagnetic valves for hydraulic supply. The electronic control system 64 may also be configured for controlling an operation of the internal combustion engine 12 and the at least one hydraulic pump to regulate a pressure in the hydrostatic system.

[0037] In the example of Fig. 1, the electronic control system 64 executes software for operation of the wheel excavator 10. However, the exemplary electronic control system 64 does not satisfy the requirements for functional safety that apply for inhibition of rotation and operation of the working device 20 when travelling on public roads.

[0038] For inhibiting the rotation of the superstructure 14 with respect to the undercarriage 16, the mobile excavator 10 comprises a locking device 76 configured for rotatably fixing the superstructure with respect to the undercarriage. The locking device 76 may be operated by supply of hydraulic fluid from the hydrostatic system. In the example of Fig. 1, the locking device 76 assumes a locked state when no hydraulic fluid is supplied to the locking device 76. For example, the locking device 76 may be spring loaded so as to assume the locked state when no hydraulic fluid is supplied. In the locked state, the locking device 76 inhibits rotation of the superstructure 14 with respect to the undercarriage 16, e.g. by locking the superstructure 14 against the undercarriage 16. Further, when hydraulic fluid is supplied to the locking device 76, the locking device may assume a free state. In the free state, the locking device 76 does not inhibit the rotation of the superstructure 14 relative to the undercarriage 16. The locking device 76 may, e.g., be a swing brake of the wheel excavator, which may comprise a multiple disk brake. The locking device 76 may also be, e.g. any other type of friction brake suitable for preventing rotation of the superstructure 14 relative to the undercarriage 16.

[0039] For example, the wheel excavator 10 may comprise a swing gear or a swing drive comprising the locking device 76. The swing gear may be configured for transforming a torque provided by at least one of the hydraulic motors so as to rotate the superstructure 14 with respect to the undercarriage 16.

[0040] Fig. 2 shows a view from above of the wheel excavator 10. As can be seen, the superstructure 14 can generally be rotated with respect to the undercarriage 16 about an axis 38 (not shown in Fig. 2) which comprises point P. The superstructure 14 comprises a superstructure longitudinal axis 62. The undercarriage 16 comprises an undercarriage longitudinal axis 60.

[0041] The locking device 76 is configured in the locked state for inhibiting a rotation of the superstructure 14 with respect to the undercarriage 16. That is, in the locked state, the angle a is constant. In the free state, a change of the angle a, e.g., by means of corresponding hydraulic motors, is possible.

[0042] Fig. 3 a shows an exemplary structure of a switch unit 80, two solenoids 90, 92 of electro-magnetic valves and the electronic control system 64. The switch unit 80 may, e.g., be arranged in the operator station 22.

[0043] The first electromagnetic valve is configured for providing hydraulic supply to the locking device 76 when the first solenoid 90 receives electric power. The electric power can be provided according to a control signal from the electronic control system 64. For example, the electronic control system 64 can comprise an output connected to the first solenoid 90. When the locking device 76 receives hydraulic liquid, the locking device 76 assumes the free state, as discussed above. When the first solenoid 90 is disconnected from electric power, hydraulic supply to the locking device 76 is cut and the locking device 76 assumes the locked state.

[0044] The second electromagnetic valve is configured for pilot hydraulic supply for operating the working device 20. The working device 20, particularly the implement 32, can be moved by means of the pilot hydraulic supply. When the pilot hydraulic supply is cut, at least the working tool actuator 50 stops to move, particularly also the boom actuator 34 and the stick actuator 44. The second electromagnetic valve comprises the second solenoid 92. When the second solenoid 92 is provided with electric power, the second electromagnetic valve provides the pilot hydraulic supply. When the second solenoid 92 is disconnected from the electric power, the pilot hydraulic supply is cut.

[0045] The switch unit 80 comprises at least a first switch position and a second switch position. In the first switch position, the switch unit 80 is configured for connecting each of the first solenoid 90 and the second solenoid 92 to the electronic control system 64. Thus, the electronic control system 64 can control the working device 20 and the locking device 76, e.g., based on a driver’s input.

[0046] In the second switch position, the switch unit 80 is configured for disconnecting each of the first solenoid 90 and the second solenoid 92 from the electronic control system 64. Thus, hydraulic supply to the locking device 76 and pilot hydraulic supply to the implement 32, particularly to the working device 20, is cut. Hence, the locking device 76 assumes the locked state independent of any control signal from the electronic control system 64 and the implement 32, particularly the working device 20, cannot be moved with respect to the superstructure 14 regardless of any control signal from the electronic control system 64. Thus, optionally advantageously, rotation of the superstructure 14 with respect to the undercarriage 16 and actuation of the implement 32 can be inhibited with a high level of functional safety without requiring the electronic control system 64 to satisfy said high level of functional safety. Hence, optionally advantageously, a less complex software and / or controller may be used for the electronic control system 64 for a wheel excavator 10 compliant with legal requirements for travelling on public roads.

[0047] In other words, the locking device may rotatably fix the superstructure with respect to the undercarriage when the first solenoid is disconnected from electric power.

[0048] Fig. 3b shows an exemplary embodiment of the switch unit 80. The switch unit 80 may for example be a rocker switch. However, the switch unit may also be another type of switch, such as a push button or a rotatable switch. The switch unit 80 may, for example, be a dual pole dual throw switch (dpdt switch) or a three poles dual throw switch (3pdt switch).

[0049] Further, the electronic control system 64 is configured for detecting a fault of the first solenoid 90 and a fault of the second solenoid 92. Based on at least one of the faults, the electronic control system 64 outputs an error message and / or a diagnostics message. In the exemplary structure shown in Fig. 3a, the electronic control system 64 is configured for not generating an error message upon detecting disconnection, particularly substantially simultaneous disconnection, of both of the first solenoid 90 and the second solenoid 92. Thus, optionally advantageously, error messages that would be erroneously generated due to use of the switch unit 80 can be suppressed.

[0050] Fig. 4 shows another exemplary structure of a switch unit 80, the two solenoids 90, 92 of the electro-magnetic valves and the electronic control system 64. In contrast to Fig. 3a, the switch unit 80 further comprises an output to the electronic control system 64 configured for indicating a state of the switch. In the example of Fig. 4, the output can, e.g., be another pole that is switched, such as a third pole o the switch unit 80 in the example of a 3pdt switch. The output may however also be a more complex output.

[0051] In the exemplary structure shown in Fig. 4, the electronic control system 64 is configured for not generating an error message upon detecting disconnection of the solenoids 90, 92 and receiving the output of the switch indicating the second switch position. Optionally advantageously, the output may thus enable the electronic control system 64 to provide more accurate fault detection and / or diagnostics.

[0052] In some example embodiments, the switch unit 80 further comprises a third switch position. In the third switch position, the switch unit 80 is configured for disconnecting the first solenoid 90 from the electronic control system and for connecting the second solenoid 92 to the electronic control system. Thus, in the third switch position, only rotation of the superstructure 14 with respect to the undercarriage 16 may be inhibited, optionally advantageously facilitating loading and / or unloading of the wheel excavator 10 to or from a vessel, such as a trailer, a semi-trailer or a ship.

[0053] Fig. 6a shows an example where the third switch position is a third mechanical switch position of the switch unit 80. In such an example, the switch unit 80 may comprise a dp3t switch, which comprises three poles (and hence three positions). A corresponding embodiment of the switch unit 80 is shown in Fig. 6a.

[0054] Fig. 6b shows an example where the third switch position of the switch unit 80 is assumed by actuation of an additional switch component 82, such as an dpst switch. In the third switch position of the switch unit 80, the additional switch component 82 may, e.g., be in a disconnected state and thus disconnect the first solenoid 90 from the electronic control system 64. A second pole of the dpst switch may be connected to the electronic control system 64 to indicate a position of the switch component 82, thus optionally advantageously enabling the electronic control system 64 to accurately determine the position of the switch unit 80 with the additional switch position.

[0055] Briefly summarized, in an embodiment, the switch unit 80 may comprise three configurations. In a first configuration, which may be the first switch position, the first solenoid 90 and the second solenoid 92 are connected to the electronic control system 64 by means of the switch unit 80. In a second configuration, which may be the second switch position, the first solenoid 90 and the second solenoid 92 may both be disconnected from the electronic control system 64 by means of the switch unit 80. In a third configuration, which may be the third switch position, the first solenoid 90 may be disconnected from the electronic control system 64 and the second solenoid 92 may be connected to the electronic control system 64 by means of the switch unit 80.

[0056] The first solenoid 90 and the second solenoid 92 may only be connected to the electronic control system 64 by means of the switch unit 80. Thus, optionally advantageously, safe disconnection of the solenoids from the electronic control system 64 by means of the switch unit 80 may be facilitated.

[0057] The locking device 76 may be configured for assuming the free state if at least a pre-determined amount of pressurized oil is provided to the locking device. The locking device 76 may be configured for assuming a locked state if less than the pre-determined amount of pressurized oil is provided to the locking device. In the locked state, the locking device 76 may rotatably fix the superstructure 14 with respect to the undercarriage 16. In other words, optionally advantageously, in case of a failure of the hydrostatic system, the superstructure 14 may be secured with respect to the undercarriage 16.

[0058] The wheel excavator 10 may comprise a rotary joint that fastens the superstructure 14 to the undercarriage 16 in a rotatable manner.

[0059] Fig. 5a shows an exemplary embodiment of a method. In the example shown in Fig. 5a, the method comprises using the wheel excavator 10. The method comprises a first step S1 comprising actuating the switch unit 80 to the first switch position. Step SI may, for example, be initiated or performed by a driver of the wheel excavator 10. The method of Fig. 5a comprises subsequently executing step la. Step Sia comprises connecting the first solenoid 90 and the second solenoid 92 to the electronic control system 64 by means of the switch unit 80. The connection may correspond to the structure shown in Fig. 3a or Fig. 4.

[0060] Further, the method shown in Fig. 5a comprises a second step S2. The second step S2 comprises actuating the switch unit 80 to the second switch positon. Step S2 may, for example, be initiated or performed by a driver of the wheel excavator 10 prior to moving the wheel excavator 10 over a public road. Subsequently, the method of Fig. 5a comprises step S2a, which comprises disconnecting the first solenoid 90 and the second solenoid 92 from the electronic control system 64 by means of the switch unit 80. Thus, optionally advantageously, rotation of the superstructure 14 relative to the undercarriage 16 may be inhibited with a high level of functional safety without requiring a corresponding level of functional safety of the electronic control system 64.

[0061] The skilled person will easily understand that an order of the steps of the method may be changed so that, e.g., the switch may initially be in the second switch position, and the switch may be moved to the first switch position afterwards.

[0062] Fig. 5b shows another exemplary embodiment of the method. The method of Fig. 5b further comprises a third step S3. In Fig. 5b, the third step S3 is arranged after the first step SI and the second step S2, but it may also be carried out before step SI and / or step S2.

[0063] The third step S3 comprises actuating the switch unit 80 to the third switch position. Subsequently, the method comprises step S3 a, which comprises disconnecting the first solenoid 90 from the electronic control system 64 and connecting the second solenoid 92 to the electronic control system 64 by means of the switch unit 80. Thus, optionally advantageously, while rotation of the superstructure 14 with respect to the undercarriage 16 is inhibited, the working device 20 may still be operated and loading and / or unloading of the wheel excavator 10 to or from a vessel may be facilitated.

[0064] It will be obvious for a person skilled in the art that these embodiments and items only depict examples of a plurality of possibilities. Hence, the embodiments shown here should not be understood to form a limitation of these features and configurations. Any possible combination and configuration of the described features can be chosen according to the scope of the invention. Industrial applicability

[0065] As noted above, embodiments of the present disclosure relate to a wheel excavator and a method for locking a superstructure that is fastened to an undercarriage of a wheel excavator in a rotatable manner.

[0066] The disclosed inventor optionally advantageously allows to obtain a wheel excavator that may inhibit rotation of the superstructure and operation of an implement with a high level of functional safety, without requiring an electronic control system comprising a same level of functional safety. However, the functional safety provided by the present invention may be superior to a level of functional safety provided by only using mechanical locking pins or by using a system that only locks the implement or the rotation of the superstructure with respect to the undercarriage.

[0067] The invention may, e.g., used in the design of wheel excavators and be built in. However, the invention may also be used as retrofit solution for wheel excavators comprising a hydrostatic system and control by means of electromagnetic valves.

[0068] The method may be implemented with known wheeled excavators in order to improve a level of function safety of the wheel excavator.

Claims

What is claimed is:

1. A wheel excavator, comprisingan undercarriage;a superstructure fastened to the undercarriage in a rotatable manner;a working device for receiving at least one implement;an electronic control system;a locking device configured for rotatably fixing the superstructure with respect to the undercarriage in a releasable manner;a switch unit, particularly a manually operable electromechanical switch unit;a hydrostatic system configured for operating the working device and the locking device, the hydrostatic system comprisinga first electromagnetic valve configured for providing hydraulic supply to the locking device, the first electromagnetic valve comprising a first solenoid, anda second electromagnetic valve configured for pilot hydraulic supply for operating the working device, the second electromagnetic valve comprising a second solenoid; andwherein the switch unit comprises at leasta first switch position, in which the switch unit is configured for connecting each of the first solenoid and the second solenoid to the electronic control system, anda second switch position, in which the switch unit is configured for disconnecting each of the first solenoid and the second solenoid from the electronic control system.

2. The wheel excavator according to claim 1, wherein the locking device rotatably fixes the superstructure with respect to the undercarriage when the first solenoid is disconnected from electric power.

3. The wheel excavator according to any of claims 1 -2, wherein the switch unit is arranged in an operator station.

4. The wheel excavator according to any of claims 1-3, wherein the electronic control system is configured for detecting a fault of the first solenoid and a fault of the second solenoid and for outputting an error message based on at least one of the faults, andwherein further, the electronic control system is configured for not generating an error message upon detecting disconnection of both of the first solenoid and the second solenoid.

5. The wheel excavator according to any of claims 1-4, wherein the switch unit further comprises a third switch position, andwherein in the third switch position, the switch unit is configured for disconnecting the first solenoid from the electronic control system and for connecting the second solenoid to the electronic control system.

6. The wheel excavator according to any of claims 1-5, wherein the switch unit further comprises a connection to the electronic control system configured for communicating an active switch position of the switch unit.

7. The wheel excavator according to any of claims 1-6, wherein the first solenoid and the second solenoid are only connected to the electronic control system by means of the switch unit.

8. The wheel excavator according to any of claims 1-7, wherein the locking device is configured for assuming a free state if at least a predetermined amount of pressurized oil is provided to the locking device, and wherein the locking device is configured for assuming a locked state if less than the pre-determined amount of pressurized oil is provided to the locking device, andwherein in the locked state, the locking device rotatably fixes the superstructure with respect to the undercarriage.

9. The wheel excavator according to any of the preceding claims, further comprising a rotary joint that fastens the superstructure to the undercarriage in a rotatable manner.

10. A method for locking a superstructure that is fastened to an undercarriage of a wheel excavator in a rotatable manner,the wheel excavator further comprisinga working device for receiving at least one implement;an electronic control system;a locking device;a switch unit configured for being operated by a driver; anda hydrostatic system comprisinga first electromagnetic valve arranged to provide hydraulic supply to the locking device, the first electromagnetic valve comprising a first solenoid, anda second electromagnetic valve arranged for pilot hydraulic supply for operating the working device, the second electromagnetic valve comprising a second solenoid;the method comprising a first step comprising actuating the switch unit to assume a first switch position, thus connecting each of the first solenoidand the second solenoid to the electronic control system by means of the switch unit, enabling pilot hydraulic supply for operating the working device and enabling hydraulic supply to the locking device, anda second step comprising actuating the switch unit to assume a second switch position, thus disconnecting each of the first solenoid and the second solenoid from the electronic control system by means of the switch unit, stopping pilot hydraulic supply for operating the working device and stopping hydraulic supply to the locking device.

11. The method according to claim 10, the method further comprising a third step comprising actuating the switch to a third switch position, thus disconnecting the first solenoid from the electronic control system and connecting the second solenoid to the electronic control system by means of the switch unit, enabling pilot hydraulic supply for operating the working device, and stopping hydraulic supply to the locking device.Application No: GB2417294.2 Examiner: Kieran ChanClaims searched: 1-11 Date of search: 28 April 2025Patents Act 1977: Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance A - US9285023 B2 (HITACHI CONSTRUCTION) See Figures for a connection / disconnection unit that includes a switch 26 for controlling an electromagnetic valve that supplies hydraulic fluid to a swing operation tool 15. A - US2017 / 282857 Al (HITACHI CONSTRUCTION) See Figures for a gate lock switch for controlling pilot pressure supplied to a swing hydraulic actuator. A - US2013 / 243557 Al (HITACHI CONSTRUCTION) See Figures for a controller 80 for switching between hydraulic swing modes. A - JPH0489933 A (CATERPILLAR MITSUBISHI LTD) See Figures for a swing bearing lock operation swing 15 comprising a solenoid valve 14. A - JP2000204604 A (SUMITOMO CONSTR) See Figures for an electromagnetic swing lock switch.Categories:X Document indicating lack of novelty or inventive step A Document indicating technological background and / or state of the art. Y Document indicating lack of inventive step if combined with one or more other documents of same category. P Document published on or after the declared priority date but before the filing date of this invention. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:Search of GB, EP, WO &US patent documents classified in the following areas of the UKCX :International Classification:Subclass Subgroup Valid From E02F 0009 / 12 01 / 01 / 2006 E02F 0009 / 20 01 / 01 / 2006

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