VEHICLE

Description

[0001] The invention relates to a vehicle having a mast arrangement thereon, wherein at least one support device is provided on the vehicle.

[0002] Such vehicles, for example, also have a slurry pump and are then also known as concrete pumps. They have a hydraulic drive system with which both the mast assembly and at least one support device can be moved. The support device serves to support or align the vehicle. The mast assembly on it is moved and aligned hydraulically and serves, for example, to transport concrete to a specific point on a construction site for further processing using the concrete pump or slurry pump.

[0003] The hydraulic drive arrangements and especially the valve arrangements are relatively complex and therefore expensive to provide.

[0004] DE 10 2018 202 148 B3 discloses a mobile hydraulic system for a mobile crane, for example, which can control retractable and extendable supports as well as a versatile mast. The mobile hydraulic system features two directional spool valves corresponding to proportional valves, each of which is followed by a switching valve. Each switching valve can supply two outlets as hydraulic consumer connections.

[0005] EP 2 594 807 A1 discloses a hydraulic system for, for example, an aerial work platform. Here, too, several proportional valves are known in a valve arrangement, with switching elements arranged downstream as changeover valve devices. These switching elements can be used to drive work machines designed as hydraulic cylinders.

[0006] EP 0 670 946 B1 discloses a vehicle with outriggers, a mast assembly, and a slurry pump. The outriggers and mast sections are driven by individual hydraulic cylinders. A proportional valve is provided as a control valve for each hydraulic cylinder.

[0007] WO 2013 / 021404 A2 discloses another vehicle with outriggers and a mast assembly (see Figs. 3A and 3B). Here, too, the outriggers and the mast assembly are moved by a hydraulic drive assembly. For this purpose, a large number of outlets are provided from a switching device on the hydraulic drive assembly, with the outlets leading to the outriggers or the mast assembly. The outlets are divided into functional groups, with the outlets being arranged alternately on the switching device, independent of the groups. TASK AND SOLUTION

[0008] The invention is based on the object of creating a vehicle as mentioned above with which problems of the prior art can be solved and, in particular, it is possible to provide a simpler hydraulic drive arrangement and valve arrangement.

[0009] This object is achieved by a vehicle having the features of claim 1. Advantageous and preferred embodiments of the invention are the subject of the further claims and are explained in more detail below. The wording of the claims is incorporated into the content of the description by express reference.

[0010] It is provided that the vehicle has at least one outrigger in order to be able to support and / or align it. Advantageously, there are at least two outriggers, particularly advantageously at least four outriggers, which are arranged in a distributed manner, preferably two on each side. A rotatable mast arrangement is provided on or at the vehicle. It has several independently movable sub-mast members, so that in addition to the rotary drive for the mast arrangement, each of the sub-mast members advantageously also has its own hydraulic drive. These hydraulic drives are part of a hydraulic drive arrangement which is provided for the at least one outrigger and the mast arrangement. The plurality of hydraulic drives can each assume the movement of each outrigger and each of the movable sub-mast members, advantageously as hydraulic cylinders.A hydraulic drive is also advantageously provided for rotating the mast arrangement relative to the vehicle, and is specially designed for this purpose.

[0011] To control the hydraulic drive assembly, a valve assembly is provided, which controls the hydraulic drives of the hydraulic drive assembly in a conventional manner. This allows each support device and / or each of the sub-mast sections, and thus the entire mast assembly, to be moved.

[0012] According to the invention, the valve arrangement comprises a group of proportional valves, i.e. at least two proportional valves, with which the hydraulic drive arrangement can be acted upon or which are designed to control the hydraulic drive arrangement. By designing them as proportional valves, such control can be carried out very sensitively and precisely. This allows the hydraulic drives of the drive arrangement to be well controlled in order to be able to effectively control or move the functional units of the at least one support device and the partial mast members driven by them. The valve arrangement further comprises a group of changeover valve devices, i.e. at least two changeover valve devices, each of which is connected to at least one hydraulic drive, i.e. to a hydraulic drive of the at least one support device or the partial mast members.The aforementioned switching valve devices are connected downstream of the proportional valves, with exactly one switching valve device or several switching valve devices each being supplied by exactly one proportional valve or each being connected downstream of exactly one single proportional valve. The outputs of at least two proportional valves are routed exclusively to the inputs of the switching valve devices, i.e., they are not yet routed directly from these two proportional valves to one of the hydraulic drives. This means that the invention makes it possible to provide a switching valve device downstream of at least two proportional valves, and advantageously for even more proportional valves in the valve arrangement, which can, so to speak, direct the control of the movement of the proportional valves to different hydraulic drives.This allows the number of complex proportional valves to be reduced, and the switching valve devices downstream of these proportional valves allow the control of the movement, or more specifically the hydraulic fluid, to be directed to the hydraulic drive that is to be driven. Although a hydraulic drive then has to be controlled or adjusted using the switching valve device before it can be actuated or activated, the overall design effort can be significantly reduced.

[0013] Preferably, the vehicle itself has, or can be connected to, a slurry pump that pumps slurry or concrete into a pipeline attached to the mast assembly. This is known.

[0014] Advantageously, the outputs of all proportional valves are connected exclusively to the inputs of the switching valve devices, so that the number of proportional valves required can be reduced to a maximum.

[0015] In a further advantageous embodiment of the invention, exactly one single switching valve device can be connected downstream of each single proportional valve, i.e., supplied by this valve. This can be particularly advantageously provided for each proportional valve of the valve arrangement, so that exactly one single switching valve device is connected downstream of each single proportional valve. These switching valve devices can then be designed similarly or identically and grouped similarly, which will be explained in more detail below.

[0016] It can be advantageously provided that all switching valve devices have the same adjustment and switching options, so that they are functionally equivalent. In yet another advantageous embodiment of the invention, it can be provided that all switching valve devices are identical. This can reduce costs and effort during production and, above all, during repair because the required number of parts is reduced.

[0017] In yet another embodiment of the invention, it can be provided that all proportional valves also have the same adjustment and switching options, and particularly advantageously, are identical. This also allows the aforementioned advantage of reduced complexity to be achieved.

[0018] In an alternative embodiment, for better adaptation to the respective application, it can be provided that the proportional valves are different; advantageously, at least two different types of proportional valves can be provided. These can vary, in particular, with regard to their spool configuration, which can particularly preferably affect their oil quantity setting or passage and / or the center position of a spool of these proportional valves, generally for the hydraulic fluid. For example, it can be provided that some proportional valves are designed for larger quantities of hydraulic fluid as a throughput because the hydraulic drives controlled by them require a larger throughput.

[0019] The invention provides that each of the switching valve devices has between two and five outlets. There are exactly three outlets, so that the technical complexity of a switching valve device remains within technically reasonable limits. Each of the outlets of a switching valve device has two connections that lead to or into the switching valve device. This means that each outlet can advantageously lead to one of the hydraulic drives of the support devices or to one of the hydraulic drives of the mast arrangement. Thus, the invention provides that for each switching valve device, exactly two outlets lead to hydraulic drives of the support device and exactly one outlet leads to hydraulic drives of the mast arrangement.With these two outlets to the hydraulic drives of the at least one support device, preferably to a plurality of support devices, it can be provided that at least one support device is arranged on each side of the vehicle, advantageously two support devices on each side. These support devices can then be grouped into a left side of the vehicle and a right side of the vehicle. Thus, especially in the case of two support devices on each side, the switching valve devices can be used to set that at exactly one time only the support devices on the left side or only the support devices on the right side can be operated or moved. The proportional valves are then connected only to these subgroups of support devices by means of the switching valve devices, which makes it easier to align the vehicle and, above all, can reduce operating errors.In a corresponding form, it can then be provided that in one position of the switching valve devices only the hydraulic drives of the mast arrangement can be moved or controlled, so that no negative effect on the alignment or support of the vehicle is possible, while in the main operation of the vehicle the mast arrangement is actually intended to be moved.

[0020] According to the invention, the multiple outlets on each switching valve device are arranged in a row, specifically all outlets of this switching valve device. Thus, the outlets at the beginning and end of the row each lead to one of the hydraulic drives of the support devices. A middle outlet in the row then leads to one of the hydraulic drives of the mast arrangement. The hydraulic drives at the beginning and end of the row are then advantageously routed to support devices on the left or right side of the vehicle, respectively.

[0021] It is advantageous that a selector mode valve is connected upstream of the group of proportional valves, specifically between the group of proportional valves and an oil pump or pump for hydraulic fluid. It can be particularly advantageous that only a single feed with the oil pump is provided, wherein an input module can also be connected upstream of the selector mode valve. Such a selector mode valve is preferably designed to switch the changeover valve devices. In particular, the selector mode valve can be designed to switch several or advantageously all changeover valve devices simultaneously and in the same way between a position for one outlet. With reference to the aforementioned design of the changeover valve devices with rows of outlets, this means that they are switched simultaneously and in the same way between a position for one of these outlets.In yet another embodiment of the invention, it can be provided that switching the switching valve devices by means of the aforementioned selector valve switches these switching valve devices either to control hydraulic drives of the support devices only, on the one hand, or to control hydraulic drives of the mast assembly only, on the other. Thus, there is, so to speak, a support operating mode and a mast operating mode, whereby the support operating mode can be further subdivided into a left side and a right side of the vehicle.

[0022] This allows the hydraulic drives in the support devices to be divided into at least two groups, advantageously into exactly two groups: the left side of the vehicle and the right side of the vehicle. This advantageously ensures that no support device can be adjusted simultaneously or jointly on both sides, but only on one side or only on the other. This improves safety when operating the vehicle or a slurry pump, especially when supporting the vehicle, which is very safety-critical.

[0023] In an advantageous embodiment of the invention, a monitoring device is provided which is designed to determine whether all the changeover valve devices are in the same position. In this case, as described above, they can only control hydraulic drives of the support devices on the one hand or only hydraulic drives of the mast arrangement on the other hand, or control a subdivided group of hydraulic drives. This monitoring device is therefore also intended to ensure and monitor the aforementioned increase in safety. It is advantageously provided that the monitoring device closes a safety valve in the event that not all the changeover valve devices are in the same position. This safety valve, in turn, is connected upstream of the proportional valves, preferably also upstream of the selector mode valve. In this way, the entire valve arrangement cannot detect any pressure change orDo not initiate any control for any of the hydraulic drives of the hydraulic drive arrangement unless all changeover valve devices are in the same position.

[0024] In a first embodiment of the invention, said monitoring device can have means for hydraulic feedback, in particular a hydraulic line. These means for hydraulic feedback lead from each switching valve device through all pre-selector spools of the switching valve devices such that they form a continuous or open feedback line to the safety valve. This feedback line is open in the event that all pre-selector spools of all switching valve devices are in the same position. The feedback line is interrupted in the event that at least one pre-selector spool of a switching valve device is in a different position than at least one pre-selector spool of another switching valve device, i.e. when the position of one pre-selector spool differs from a position of one of the other pre-selector spools.If this feedback line is interrupted, the safety valve closes, so that the proportional valves cannot be controlled and no hydraulic drive can take place.

[0025] In a second embodiment of the invention, the monitoring device also has means for feedback, but these means are electrically designed or designed for electrical feedback. Here, too, an electrical line can lead as a feedback line through all pre-selector slides of the changeover valve devices, for example, formed by corresponding electrical switches or contact means, so that the electrical feedback line is continuous or closed as an electrical contact in the event that all pre-selector slides of all changeover valve devices are in the same position. Electrical feedback is interrupted in the other case, in which not all pre-selector slides of the changeover valve devices are in one or the same position.

[0026] Compared to the two aforementioned feedback options, hydraulic feedback is more reliable because the condition that all preselector spools of the switching valve assembly are in the same position must be met. If this condition is not met, which is unlikely to be the case if the hydraulic feedback is malfunctioning, the hydraulic actuators cannot be operated. With electrical feedback, a through-hole connection could also be caused by other faults, although the probability of this is low and can be further reduced through structural design.

[0027] Advantageously, the switching valve devices and / or the aforementioned selector valve can be electrically controlled by means of a control device. This is particularly advantageously done electrohydraulically in order to ensure efficient application of any possible actuating forces.

[0028] A control device can have operating elements for an operator, for example push buttons or levers, to operate the individual hydraulic drives. The operating elements of the control device are advantageously provided centrally or jointly, for example at a so-called central operating point. This allows an operator to control the aforementioned functional units of the at least one support device and the mast arrangement, relatively conveniently, all from one location. Such a control device can advantageously be located some distance from the at least one support device and the mast arrangement for reasons of operational safety or accident prevention, and possibly also to provide a better overview of the operation. The control device can have a type of control panel or operating console, as is known per se.It can also be designed as a radio remote control and thus mobile so that it can be used at a distance from the vehicle.

[0029] In a further advantageous embodiment of the invention, it can be provided that the valve arrangement has a common valve carrier. This advantageously allows all proportional valves and all changeover valve devices to be arranged on the common valve carrier. This makes a hydraulic connection easily possible. The aforementioned selector valve can also be provided here. The valve carrier can advantageously have a carrier plate to which the aforementioned proportional valves and changeover valve devices can be attached. This easily facilitates the supply of hydraulic fluid from the aforementioned oil pump. Furthermore, the previously described advantageous monitoring device with the two feedback options can also be well constructed because the changeover valve devices are provided close to one another.

[0030] These and other features emerge not only from the claims but also from the description and the drawings. The individual features may be implemented individually or in combination in one embodiment of the invention and in other fields, and may represent advantageous and protectable embodiments for which protection is claimed here. The division of the application into individual sections and subheadings does not limit the general validity of the statements made therein. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] An embodiment of the invention is schematically illustrated in the drawings and explained in more detail below. The drawings show: Fig. 1 a simplified schematic representation of a vehicle according to the invention as a so-called concrete pump with supports and a mast arrangement, Fig. 2 a highly simplified representation of a valve arrangement according to the invention for the vehicle from Fig. 1 with a group of proportional valves followed by a group of switching valves, Fig. 3 a detailed representation of the structure of the hydraulic arrangement including various control options for the supports and the mast arrangement and Fig. 4 a slightly enlarged representation of the valve arrangement from Fig. 3 . DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In the Fig. 1a vehicle 11 is shown, which is also known as a so-called concrete pump. The vehicle 11 has a driver's cab 12 at the front and a large usable area 14 at the rear. On the usable area, two outriggers 16 at the front and two outriggers 17 at the rear are provided, two on each side, which are designed in a known manner. A support 16l at the front left is shown, which can also be extended to different lengths, as will be explained below. A support 17l is provided at the rear left. Both outriggers 16 and 17 can be pivoted in a horizontal plane within a certain range and extended downwards to different distances.

[0033] On the working area 14, a mast arrangement 20 is provided with four mast sections 21b to 21e on a turntable 23. The mast sections 21b-e are folded together for transport, in the Fig. 3 they are at least schematically unfolded.

[0034] At the rear of the vehicle 11, a pump module 25 is provided, into which concrete is poured from above and which then, in a known manner, pumps this poured concrete or generally thick material through a movable line along the mast arrangement 20 or its mast members 21.

[0035] Furthermore, a control panel 27 is provided on the usable area 14 as the aforementioned control device or operating point. A valve arrangement 30 is shown schematically next to it, but this does not necessarily have to be visible. Its valves are controlled by the control panel 27.

[0036] In the simplified representation according to Fig. 2A valve assembly 30 is shown in detail. A hydraulic pump 32 is shown at the bottom right, which pumps hydraulic fluid under pressure into the valve assembly 30. The valve assembly 30 has a valve carrier plate 34, on which proportional valves 36 are arranged or mounted in the lower area, and switching valves 40 as a group in the upper area.

[0037] Each of the proportional valves 36a to 36e, each of which has a control 37a to 37e, is connected directly to exactly one downstream switching valve 40a to 40e. The proportional valves 36a to 36e and the switching valves 40a to 40e are each designed identically. The proportional valves 36a to 36e are advantageously designed as pressure-compensated proportional valves.

[0038] The switching valves 40a to 40e each have three outputs, which are arranged identically for all switching valves. Switching between the three outputs is possible using an adjustable slide 41a to 41e for each switching valve 40a to 40e. All slides 41a to 41e are moved simultaneously by a common actuating device 43 and are also moved in the same way. An actuator 44 is provided for this purpose. The actuator 44, like the control units 37a to 37e of the proportional valves 36, is connected to one of several control elements 28 of the control panel 27 for control purposes.

[0039] The lowest outlet of the switching valves 40a to 40e goes to the group Al of the left supports 16l and 17l. The middle outlets M all go to the mast assembly 20 including the turntable 23. The uppermost outlets Ar go to the Fig. 3 right supports 16r and 17r shown top right.

[0040] The simultaneous adjustment within the switching valves 40a to 40e according to the invention and described above thus ensures that either only the left-hand outriggers, only the mast assembly including the turntable, or only the right-hand outriggers or their hydraulic drives can be controlled. A feedback line or feedback signal as described above is not yet installed or shown here.

[0041] In the Fig. 2 In the position shown of the slides 41a to 41e in the middle position for the mast assembly 20 or the turntable 23, a hydraulic drive of the mast assembly 20 or the turntable 23 can be driven by means of the proportional valves 36a to 36e. This is shown in Fig. 3clearly visible at the top center. The first switching valve 40a is responsible for the turntable 23; in the middle position, it is responsible for the mast arrangement M. In the lower position, it is responsible for the right-hand outriggers Ar, specifically for the horizontal extension of the front right outrigger 16r. In the uppermost position, it is responsible for the horizontal extension of the left front outrigger 16l and controls the corresponding hydraulic drive. If the switching valve 40a is in one of the three positions, then by correspondingly actuating the precisely and directly assigned proportional valve 36a using the control panel 27, either the turntable 23 with the mast arrangement 20 on it can be rotated in one direction or the other. In one of the two other positions, either the left front outrigger 16l or the right front outrigger 16r can be moved further out or further in horizontally.It is clear that before switching the switching valve 40, the corresponding proportional valve 36 must be depressurized.

[0042] In the middle position M, the second switching valve 40b is connected to the first, lowest mast link 21b and its hydraulic drive. In the upper position, it is connected to the left front support 16l and its hydraulic drive to extend it downwards in a vertical direction. In the lower position, it is connected to the hydraulic drive of the right front support 16r to move it vertically.

[0043] The third switching valve 40c is connected to the second mast section 21c and its hydraulic drive in the middle position M, as can be seen. In the upper position, it is connected to the hydraulic drive of the left rear support 17l to extend it vertically. In the lower position, it is connected to the hydraulic drive of the right rear support 17r for vertical movement.

[0044] The fourth switching valve 40d is connected to the third mast section 21d or its hydraulic drive in the middle position M. In the upper position, it is connected to a hydraulic drive for horizontally pivoting the left front support 16l. In the lower position, it is connected to the hydraulic drive for the right front support 16r to pivot it back and forth in a horizontal plane.

[0045] The fifth switching valve 40e is connected in the middle position M to the hydraulic drive for the fourth and last mast section 21e. In the upper position, it is connected to the hydraulic drive for the left rear support 171 to pivot it in the horizontal plane. In the lowest position of its slide, it is connected to the hydraulic drive for the right rear support 17r to pivot it in the horizontal plane.

[0046] It is thus clear that in each of the three positions of the slide 41 of the switching valves 40, either the mast assembly 20 or its four mast sections 21b to 21e or the turntable 23 or their hydraulic drives can be controlled. In a further position, all supports 16l and 17l on the left side of the vehicle 11 can be moved, and in yet another position, all right supports 16r and 17r can be moved.

[0047] The precise hydraulic circuit diagram can be seen from the detailed illustration of the valve arrangement 30, some of which have already been described above. It can be seen how each proportional valve 36a to 36e is directly followed by a single changeover valve 40a to 40e. The proportional valves 36a to 36e and the changeover valves 40a to 40e are advantageously mounted on a common valve support plate, which is not shown here. The valve arrangement 30 also advantageously has an input module 46 at the bottom right and, downstream of this, a selector mode valve 48. Two electric pilot valves 50 are provided at the top right.

[0048] To ensure, as explained at the beginning, that all switching valves 40a to 40e or their slide valves 41a to 41e are in the same position, so that an operator knows exactly which hydraulic drive or functional unit is being actuated by actuating the corresponding proportional valve 36a to 36e via the control panel 27, a hydraulic feedback 52 is shown here in dashed lines. It passes through all switching valves 40a to 40e and is only closed when all switching valves 40a to 40e are actually in the same position. Only then is one of the aforementioned groups activated. Otherwise, the hydraulic feedback is interrupted, and as a result, it can be provided that none of the proportional valves 36a to 36e can be opened.Furthermore, a fault message should be output visually and / or acoustically, ideally at least on the control panel 27, but particularly advantageously also at another location.

[0049] By directly connecting the changeover valves 40a to 40e behind the proportional valves 36a to 36e, advantageously with short line lengths in between, a compact, easy-to-oversee and easy-to-maintain valve arrangement 30 can be created.

Claims

1. Vehicle (11) for a thick material pump device (25), wherein the vehicle comprises: - at least two support devices (16, 17) for supporting and / or aligning the vehicle (11), - a mast arrangement (20) which is rotatable and has several independently movable partial mast members (21), - a hydraulic drive arrangement for the support devices (16, 17) and the mast arrangement (20), which has hydraulic drives for moving the support devices and the movable partial mast members (21), - a valve arrangement (30) for moving one of the support devices (16, 17) and / or one of the partial mast members (21) by means of the hydraulic drive arrangement (32) and its hydraulic drives, wherein - the valve arrangement (30) has a group of proportional valves (36) for controlling the hydraulic drive arrangement, - the valve arrangement (30) has a group of switchover valve devices (40) which are each connected to at least one hydraulic drive of the support devices (16, 17) or of the partial mast members (21), - the switchover valve devices (40) are connected downstream of the proportional valves (36), - exactly one switchover valve device (40) or several switchover valve devices are supplied by exactly one proportional valve (36) or are connected downstream of exactly one single proportional valve, - outputs of the proportional valves (36) lead exclusively to inputs of the switchover valve devices (40), - each of the switchover valve devices (40) has between two and five outputs (Al, Ar, M), each output leading to one of the hydraulic drives of the support devices (16, 17) or the mast arrangement (20), characterized in that - in each switchover valve device (40), exactly two outputs (Al, Ar) lead to the hydraulic drives of the support devices (16, 17) and exactly one output (M) leads to the hydraulic drives of the mast arrangement (20), - the multiple outputs (Al, Ar, M) on each switchover valve device (40) are arranged in a row, - the outputs (Al, Ar) at the beginning of the row and at the end of the row lead to one of the hydraulic drives of the support devices (16, 17), - a middle output (M) of the row leads to one of the hydraulic drives of the mast arrangement (20).

2. Vehicle according to claim 1, characterized in that exactly one single switchover valve device (40) is connected downstream of each proportional valve (36), in particular exactly one single switchover valve device (40) is connected downstream of each proportional valve (36).

3. Vehicle according to claim 1 or 2, characterized in that all switchover valve devices (40) have the same setting options and switching options, in particular are identical.

4. Vehicle according to one of the preceding claims, characterized in that all proportional valves (36) have the same setting options and switching options, in particular are identical.

5. Vehicle according to one of the preceding claims, characterized in that each of the switchover valve devices (40) has three or four outputs (Al, Ar, M).

6. Vehicle according to one of the preceding claims, characterized in that a mode selection valve (48) is connected upstream of the group of proportional valves (36) coming from an oil pump (32), wherein preferably a single oil supply with the oil pump (32) together with an input module (46) is connected upstream of the mode selection valve (48).

7. Device according to claim 6, characterized in that the operating mode selection valve (48) is designed to switch the switchover valve devices (40), in particular to switch all changeover valve devices simultaneously and identically between respective positions for an output (Al, Ar, M).

8. Vehicle according to claim 7, characterized in that switching of the switchover valve devices (40) by means of the operating mode selection valve (48) switches these changeover valve devices to control hydraulic drives only of the support devices (16, 17) on the one hand or only of the mast arrangement (20) on the other hand.

9. Vehicle according to claim 8, characterized in that within the hydraulic drives of the support devices (16, 17), a distinction is made between at least two groups, in particular exactly two groups, in particular between support devices (16l, 17l) on the left side of the vehicle (11) and support devices (16r, 17r) on the right side of the vehicle, wherein preferably the two sides are not adjustable together and / or simultaneously.

10. Vehicle according to claim 8 or 9, characterized in that a monitoring device is provided which detects whether all switchover valve devices (40) are in the same position so that, according to claim 7, they only control hydraulic drives of the support devices (16, 17) or only hydraulic drives of the mast arrangement (20) or a subdivided group of hydraulic drives, wherein, preferably, the monitoring device closes a safety valve upstream of the proportional valves (36), in particular also upstream of the mode selection valve (48), in the event that not all of the switchover valve devices (40) are in the same position, so that the entire valve arrangement cannot cause a pressure change or control for any of the hydraulic drives of the hydraulic drive arrangement.

11. Vehicle according to claim 10, characterized in that the monitoring device has means for hydraulic feedback, wherein the means for hydraulic feedback lead from each switchover valve device (40) through all preselection slides (41) of the switchover valve devices in such a way that they form a feedback line to the safety valve, wherein the feedback line is open in the event that all preselection slides of all changeover valve devices are in the same position, and wherein the feedback line is interrupted in the event that at least one preselection slide (41) of a switchover valve device (40) is in a different position than at least one preselection slide of another changeover valve device.

12. Vehicle according to one of the preceding claims, characterized in that the switchover valve devices (40) and / or the mode selection valve (48) can be electrically controlled by means of a control device (27), in particular by an electric motor, wherein the control device has operating elements (28) for an operator, wherein the control device (27) is preferably provided at a central common location of the vehicle (11).

13. Vehicle according to claim 12, characterized in that the control device (27) is at least 1 m away from the support devices (16, 17) and the mast arrangement (20).

14. Vehicle according to one of the preceding claims, characterized in that the valve arrangement (30) is arranged on a common valve carrier, in particular all proportional valves (36) and all switchover valve devices (40) are arranged on the common valve carrier, wherein the valve carrier preferably has a carrier plate (34) for fastening the proportional valves (36) and switchover valve devices (40).