Hydraulic control block and hydraulic spindle comprising said control block

Abstract

The invention relates to a hydraulic control block for controlling a pressure medium supply of a hydraulic cylinder of a hydraulic spindle. The invention also relates to a hydraulic spindle comprising said control block.

Description

[0001] The invention relates to a hydraulic control block according to the preamble of patent claim 1, as well as a hydraulic axle with the control block according to patent claim 4.

[0002] A hydraulic axis, particularly a linear axis, especially a compact axis, features a hydraulic cylinder in a closed hydraulic circuit, or, if necessary, a partially closed hydraulic circuit to compensate for differential volume. With a low oil volume, the axis can be used to press, join, or close components with high dynamics, precision, and force. Typical applications for such axes include presses, injection molding machines, hexapods for simulators, and the like. If the axis has an additional servo drive, extremely high positioning accuracy and good electrical / electronic networking are also ensured.

[0003] A generic servo-hydraulic axle is shown in the applicant's data sheet RD 08137 / 2018 - 02. The compact axle features a servo actuator, a hydraulic control block, a hydraulic cylinder, a hydraulic accumulator, and control elements such as valves, as well as power electronics.

[0004] In addition to separate axle designs, in which the components mentioned are connected to the central control block by hoses, lines and pipes, compact designs with direct mechanical, hydraulic and electrical connections to the control block are also possible.

[0005] The control block must be individually adapted in design and production to each specific hydraulic cylinder with regard to the pressure medium volume flow and in particular the number of pressure medium-supplied working chambers, which is cost-intensive.

[0006] To supply different cylinder designs, document EP 1 316 732 A1 proposes a hydraulic control block with two supply ports. One of the two is assigned to a pressure medium source and the other to a pressure medium sink, whereby a pressure side change is possible at the supply ports, as can occur in a closed hydraulic circuit. Both supply ports are connected to the working ports of the control block via separate pressure medium flow paths. The control block accommodates two switching valves for each working port, one of which is fluidically connected to the supply port of the pressure medium source and the other to the supply port of the pressure medium sink.An attachable cylinder unit has a code that is read by a control unit when it is attached to the control block, so that the control unit can control the switching valves in a way that is adapted to the design.

[0007] Publication WO 2005 028 878 A1 shows a control block designed for operation in an open hydraulic circuit. The control block's supply interfaces are permanently assigned to the high-pressure and low-pressure sides of the hydraulic machine. Changing the pressure side at the supply interfaces is not possible.

[0008] The document DE 10 2017 219 084 A1, which originates from the applicant, shows an electro-hydraulic system with a hydraulic cylinder and at least one closed hydraulic circuit, which comprises at least one control means, a hydraulic machine and a closed hydraulic reservoir, wherein the closed hydraulic circuit is filled with degassed hydraulic fluid.

[0009] In contrast, the invention is based on the object of creating a more favorable hydraulic control block for a hydraulic or servo-hydraulic axle, as well as a corresponding axle therewith.

[0010] The first object is achieved by a hydraulic control block having the features of patent claim 1, the second object by a hydraulic axle having the features of claim 4.

[0011] Advantageous further developments of the inventions are described in the respective dependent patent claims.

[0012] A hydraulic control block for controlling the pressure medium supply of a hydraulic cylinder of a hydraulic or servo-hydraulic axle has a hydraulic circuit structure. This circuit structure comprises, in particular, fixed and switchable hydraulic components and means, such as working flow paths and valves, that are necessary for control. The circuit structure is generic with reference to several specific hydraulic cylinders with different piston area ratios. The generic circuit structure is such that one of several specific hydraulic circuit structures can be configured from it. Each circuit structure is assigned to each of the specific hydraulic cylinders.

[0013] According to the invention, the control block has a first and a second supply interface, the first of which is fluidically connectable to a high-pressure side of a hydraulic machine of the axle and the second of which is fluidically connectable to a low-pressure side of the hydraulic machine, and vice versa. According to the invention, the control block has a first working flow path that is fluidically connectable or connected to the first supply interface, and a second working flow path that is fluidically connectable or connected to the second supply interface. Thus, at least hydraulic cylinders with two, in particular opposing, piston surfaces can be supplied with pressure medium via the two working flow paths. Examples of hydraulic cylinders include differential and, alternatively, double-acting cylinders.In order to also be able to supply a third piston surface, particularly in the case of a tandem cylinder, with pressure medium via the hydraulic machine, the control block according to the invention has a third working flow path which is or can be fluidly connected to the first supply interface parallel to the first working flow path. According to the invention, at least one first working connection branches off from the first working flow path, at least one second working connection branches off from the second working flow path, and at least one third working connection branches off from the third working flow path. According to the invention, a valve is arranged in the third working flow path, via which the third working flow path can be blocked and opened. This can be an electromagnetically actuated directional control valve, in particular a switching valve. It can be a 2 / 2-way valve with a spring-loaded blocking position and an actuable flow position.The design and actuation alternatives mentioned below also apply to this valve. According to the invention, a connecting flow path is provided that branches off from or is connected to the first working flow path and opens into the third working flow path in a section of the third working flow path between the latter valve and the third working connection.

[0014] In other words, the control block contains fixed and switchable hydraulic means, in particular components and working flow paths, for several specific circuit structures. From this set of circuit structures, a specific circuit structure can be selected and configured depending on the specific hydraulic cylinder to be controlled via the control block.

[0015] In this way, it is no longer necessary to manufacture a specific control block for each specific hydraulic cylinder with a specific piston area ratio, but a generic control block can be manufactured for various specific hydraulic cylinders, which leads to unit production effects and reduced costs.

[0016] The hydraulic cylinder, whose pressure supply is controlled or regulated via the control block, can be configured with one, two, three, or four piston surfaces. In the version with two piston surfaces, it is designed, for example, as a double-acting or differential cylinder. With three, four, or more piston surfaces, designs such as tandem cylinders, rapid-acting cylinders, or telescopic cylinders are possible.

[0017] According to the invention, in a first configuration of the circuit structures, supply connections of the control block, which are fluidically connectable to a high-pressure and a low-pressure side of a hydraulic machine or hydraulic pump, can each be fluidically connectable or connected to only one working connection of the control block, which in the first circuit structure can be permanently assigned or is assigned to one of the piston surfaces of the hydraulic cylinder. Such a circuit structure can, for example, control the hydraulic cylinder in the form with two piston surfaces or hydrostatic working chambers and is known to the applicant under the designation "A" circuit structure for a differential cylinder and "B" circuit structure for a double-action cylinder.

[0018] According to the invention, in a second configuration of the circuit structures, at least one of the supply connections can be fluidically connected to or be connected to several working connections of the control block, each of which can be permanently assigned to one of the piston surfaces of the hydraulic cylinder in the second circuit structure. Such a circuit structure can, for example, control the hydraulic cylinder in a configuration with three or more piston surfaces or hydrostatic working chambers and is known to the applicant under the designation "E" circuit structure.

[0019] According to the invention, the control block has a closure means, in particular precisely or only one, which can be detachably arranged, via the optional arrangement and / or detachment of which and a concomitant, at least partially hydraulic closure of a flow path configured in the control block, one of the circuit structures can be configured or configured.

[0020] According to the invention, the closure means can be arranged or arranged in a detachable manner so as to be accessible from outside the control block.

[0021] Preferably, the closure means is a screw or a pressure-tight plug.

[0022] Alternatively, the closure means may be provided as a valve or valve arrangement that can be actuated depending on the desired configuration.

[0023] In a further development, the control block has a circulation flow path through which the second working flow path is or can be fluidically connected to the third working flow path. This can be used, in particular, for the energetic optimization of an "A" circuit structure with a connected differential cylinder.

[0024] For this purpose, the circulation flow path can be switched cycle-dependently in a further development.

[0025] A permanent connection or switching of the circulating flow path is equivalent to a short circuit in the case of an "A" circuit structure with a differential cylinder, and to the operation of a constant-speed cylinder in the case of an "E" circuit structure.

[0026] In a further development, a differential volume, in particular from the circulating flow path, is absorbed by a hydraulic accumulator.

[0027] In order to control the circulation, in a further development the control block has a circulation valve in the circulation flow path, via which the circulation can be switched, i.e. blocked and / or opened.

[0028] The circulation valve can, for example, be an electromagnetically actuated directional control valve, in particular a switching or logic valve. It can be a 2 / 2-way valve with a particularly spring-loaded shut-off position and an actuatable flow position. Alternatively, it can be a 4 / 2-way valve with two flow positions, one of which is a particularly spring-loaded basic position in which the second and third working flow paths are each connected to themselves. In the actuatable flow position, the second and third working flow paths are connected via two flow cross-sections. Alternatively, a seat valve is possible.

[0029] The control of the circulation valve, as well as all other valves mentioned in this document, can be electrical, hydraulic or pneumatic.

[0030] The working ports can be fluidically connected to one of the piston surfaces, and / or they can be closed or sealed, depending on the configured circuit structure. The corresponding working port can be easily shut down / deactivated via the aforementioned closure.

[0031] In a further development, the working ports are grouped together, each of which is assigned to one of the configured circuit structures. The groups preferably have at least the first working port and the second working port, with at least one of the groups having the third working port. Groups with four or more working ports are also possible, depending on the piston area of ​​the associated hydraulic cylinder.

[0032] Despite the multitude of configurable circuit structures, a further development in which the groups have an intersection proves to be less complex in terms of manufacturing technology. At least one of the working ports is open and connectable for several specific hydraulic cylinders, i.e., in various specifically configured circuit structures. In particular, the intersection contains the first and second working ports, thus ensuring the necessary pressure medium connection to the low-pressure and high-pressure sides of the hydraulic machine for hydraulic cylinders with at least two piston surfaces.

[0033] The groups can be arranged on different sides of the control block for clarity.

[0034] In a further development, the circulation channel can be closed and opened depending on the actuation of the last-mentioned valve in the third working flow path.

[0035] According to the invention, a receptacle for a closure means, in particular the one according to the preceding description, is provided in each of the first working flow path and in the connecting flow path, wherein the closure means is optionally arranged in only one of the receptacles.

[0036] Preferably, the receptacles are designed identically so that only a single closure means needs to be provided for optional arrangement in the receptacles.

[0037] If the receptacles are designed differently, two locking devices must be provided, one of which is always present and the other removed when the circuit structure is configured. This further prevents accidental incorrect screwing.

[0038] In a first configuration of the circuit structures, the third working port(s) is / are closed, and the closure means is arranged in the receptacle in the first working flow path, with the receptacle in the connecting flow path being free. This corresponds to the "A" or "B" circuit structure discussed above, with the valve in the third working flow path then deciding whether to block or supply pressure medium to the working chamber of the hydraulic cylinder that is or can be connected to the first working port.

[0039] In a second configuration of the circuit structures, the receptacle in the first working flow path is free, and the closure means is arranged in the receptacle in the connecting flow path. This corresponds to the "E" circuit structure discussed above, with the valve in the third working flow path then deciding whether to connect or disconnect the third working port from the first supply interface.

[0040] In a further development, particularly in the "E" circuit structure, the first working flow path forms the inlet of a filter, which can be arranged or is arranged in particular in the control block. Alternatively, in the "A" or "B" circuit structure, sections of the first working flow path, the third working flow path, and the connecting flow path form the inlet of a filter, which can be arranged or is arranged in particular in the control block. In both cases, the filter can thus always be arranged between the high-pressure side and one of the pressurizable piston surfaces, whereby a pressure medium volume flow sufficient for filtration is always provided through the filter, regardless of the configured circuit structure.

[0041] In a further development, the control block has an accumulator flow path and a hydraulic accumulator that is fluidly connectable or connected thereto. In particular, the accumulator flow path is fluidly connectable to at least two of the working flow paths, in particular to the first and second, in particular via a check valve each.

[0042] In a further development, electrically or hydraulically actuated decompression valves are provided, via which the accumulator flow path can be connected to the first working flow path on the one hand and to the second working flow path on the other hand.

[0043] A hydraulic axle has a hydraulic control block configured according to at least one aspect of the preceding description. Furthermore, the generic circuit structure is configured by means of the closure means to a specific circuit structure of a specific hydraulic cylinder, whose working chambers are fluidically connected to the respectively assigned working port. Furthermore, the axle can have a hydraulic machine whose high-pressure and low-pressure sides are each fluidically connected to the first and second supply interfaces.

[0044] In a further development, the working connections on the control block are arranged and / or designed in such a way that a first spatial arrangement of the hydraulic cylinder and a second spatial arrangement, which is in particular rotated relative to the first, is possible.

[0045] In a further development, at least one safety valve is arranged in the first working flow path and / or the second working flow path, via which the respective working flow path can be shut off. In particular, two safety valves are provided in the working flow path for redundancy.

[0046] An exemplary embodiment of a hydraulic control block and a hydraulic axle according to the invention is shown in the drawings. The invention will now be explained with reference to the figures in these drawings.

[0047] They show: Figure 1 a hydraulic axle with a hydraulic control block with a generic hydraulic switching structure and two configurable, specific switching structures, Figure 2 the hydraulic control block according to Figure 1 in a perspective, partially transparent view, Figure 3 the hydraulic control block according to Figure 1 and 2in a partially transparent side view, and Figure 4 the hydraulic control block according to the previous figures in a cross-section.

[0048] A hydraulic axle 1 has according to Figure 1 a hydraulic control block 2, as well as a hydraulic machine 4 connected to it and a hydraulic cylinder 6 or 8 supplied with pressure medium by this and optionally connected to the control block 2. The control block 2 has a generic hydraulic switching structure.

[0049] The term "generic" in this document is to be understood in such a way that several specific switching structures, in the illustrated embodiment these are two, A and E, can be optionally configured from the generic switching structure, whereby, as already mentioned above, the switching structure A can be designated B when a synchronous cylinder is connected.

[0050] In other words, the control block 2 contains all necessary fixed and switchable hydraulic means, in particular components and pressure medium channels, in order to be able to configure several specific switching structures.

[0051] Each switching structure A, E is assigned to a specific hydraulic cylinder 6 or 8, respectively. Thus, hydraulic cylinder 6 has two working ports, and the optionally shown hydraulic cylinder 8 has three working ports. Each working port is fluidly connected to a specific piston surface or a specific working chamber of the respective hydraulic cylinder 6, 8. Two different hydraulic cylinder designs can be connected in the switching structure A (B) (single-gear / differential).

[0052] In detail, the control block 2 has a first supply interface 10, from which a first working flow path 12 originates, and a second supply interface 14, from which a second working flow path 16 originates. The supply interfaces 10, 14 are designed as supply connections. Alternatively, they can be configured as openings in the control block 2 or the like.

[0053] Fluidically connected to each of them are a high-pressure and a low-pressure side of the hydraulic machine 4. Depending on the direction of rotation of the hydraulic machine 4, which is designed with a constant displacement, the first supply connection 10 can be fluidly connected to the high-pressure side and the second supply connection 14 to the low-pressure side, or vice versa. For the purposes of the following discussion, it will be assumed that the former is the case.

[0054] The first working flow path 12 has a branch 18, at which a third working flow path 20 branches off. A valve 22, designed as a 2 / 2-way switching valve, is arranged in this third working flow path.

[0055] From the branch 18, the first working flow path 12 extends further, with a filter 24 arranged therein. Two safety valves 26 connected in series are arranged in the first working flow path 12 and downstream of the filter 24, via which the first working flow path 12 can be shut off redundantly. These valves are also designed as simple 2 / 2-way switching valves.

[0056] In continuation of the first working flow path 12, this has a branch 28. From this, two first working connections 30A and 30E branch off to a different side of the control block.

[0057] A shut-off valve 32 is arranged in the second working flow path 16, via which the second working flow path 16 can be blocked. Starting from the second supply connection 14, via the shut-off valve 32, the second working flow path 16 continues to a branch 34. From this, two second working connections 36A, 36E branch off to different sides of the control block 2.

[0058] The third working flow path 20 is continued beyond the valve 22, up to a branch 38, from which only a third working connection 40E branches off to that side of the control block 2 where the connections 30E and 36E belonging to the specific circuit or configuration E are already provided.

[0059] As already mentioned, the control block 2 can optionally supply pressure medium to the hydraulic cylinder 6 with two piston surfaces or to the hydraulic cylinder 8 with three piston surfaces, depending on the configuration.

[0060] For this purpose, a connecting flow path 42 is provided, via which the first working flow path 12 is fluidly connected to the third working flow path 20 downstream of the valve 22. A receptacle 44E is provided in the connecting flow path 42. A receptacle 44A, of identical design in the exemplary embodiment, is provided in the first working flow path 12 in a section between the branch 18 and an inlet of the connecting flow path 42.

[0061] A locking device 46, designed as a screw, in particular M18 x 1.5 (in this case according to DIN 906), can be inserted or is inserted into the respective receptacle 44E, 44A. Due to the identical design of the receptacles 44E, 44A with M18 thread in the exemplary embodiment, exactly one locking device 46 can be inserted into the corresponding receptacle 44E, 44A, depending on the desired configuration E, A.

[0062] In Figure 1In the illustrated embodiment, the closure means 46 is inserted into the receptacle 44A, whereby the circuit structure A is configured to supply hydraulic cylinders with two working chambers or piston surfaces at the working ports 30A, 36A. Then, the working ports of the circuit structure E 30E, 36E, and 40E of the configurable circuit structure E are closed. Accordingly, the hydraulic cylinder 8 is shown with the aforementioned ports optionally (outlined by dashed lines).

[0063] In the selected configuration A, the pressure medium can therefore no longer flow directly via the first working flow path 12 to the first working port 30A, but must flow via a section of the third working flow path 20, the valve 22, and the connecting flow path 42 enabled in this configuration A. Consequently, the valve 22 has the function of either supplying or blocking the annular space of the hydraulic cylinder 6 supplied by the first working port 30A with pressure medium.

[0064] To accommodate differential volumes resulting from different piston surface sizes of the hydraulic cylinders 6, 8, the hydraulic control block 2 has an accumulator flow path 48, which can be fluidically connected to the respective working flow path 12, 16 via pressure relief valves 50 preset to a pressure value. A gas-loaded hydraulic accumulator 52 is connected to the accumulator flow path 48.

[0065] In the case of configuration A, all working ports 30E, 36E and 40E, which serve to supply pressure medium to the hydraulic cylinder 8 in configuration E, are shut off. The same applies to the third working flow path 20 and its Figure 1 Blind hole shown on the left.

[0066] Once the circuit structure E is configured, the hydraulic cylinder 8, which has three working chambers or piston surfaces, can be supplied with pressure medium. The closure means 46 is then released and removed from the receptacle 44A and inserted into the receptacle 44E. Furthermore, the working ports 30A and 36A are closed, and the working ports 30E, 36E, and 40E are opened, with the third working flow path 20 still closed by the blind bore provided in the exemplary embodiment.

[0067] The outlets or working ports 30A, 30E, 36A, 36E, 40E can each be designed as individual pressure medium channels in the control block 2. Expanding the control block 2 to accommodate a larger number of outlets or working ports can increase the variability of the control block, particularly to meet market requirements.

[0068] In the circuit structure E, pressure medium can then flow via the first working flow path 12 via the branch 18 and the filter 24 directly to the first working port 30E and thus into the left annular space of the tandem cylinder 8. Since in the configuration E the connecting flow path 42 is blocked by the closure means 46, the position of the valve 22 now determines whether the annular space connected to the third working port 40E is supplied with pressure medium or not.

[0069] If it is supplied, the equally acting annular spaces of the working connections 30E and 40E are pressurized with pressure medium, which corresponds to an area summation and thus a power transmission of the hydraulic cylinder 8.

[0070] In the case of power transmission, the hydraulic pump delivers pressure fluid from the working chamber of the hydraulic cylinder 8, connected to the second working port 36E, into its working chambers connected to the first working port 30E and the third working port 40E. The circulation valve 54 is closed for this purpose.

[0071] During rapid travel of hydraulic cylinder 8, however, working ports 36E and 40E are fluidly connected and short-circuited via the circulation valve 54. The hydraulic pump then delivers pressure fluid from the working chamber connected to the second working port 36E to the working chamber connected to the first working port 30E. The very small piston area of ​​the piston limiting this area results in a high travel speed.

[0072] The filling or re-suction into the working chamber connected to the third working connection 40E is thus carried out, bypassing the hydraulic pump 4, solely via the circulating volume flow via the circulation valve 54. The three annular surfaces of the hydraulic cylinder 8 are coordinated with one another in such a way that, apart from volumes caused in particular by leakage, no differential volume has to be absorbed by the hydraulic accumulator 52.

[0073] In configuration or circuit structure A with differential cylinder 6, pressure medium can flow between working flow paths 12 and 16 via the circulation valve 54. When the differential cylinder 6 retracts, the differential volume must always be pumped into the accumulator 52. The circulation valve 54 enables the differential cylinder 6 to extend and retract at the same speed with low travel force.

[0074] The Figure 2 and 3show the hydraulic control block in perspective and in a partially transparent side view, with the receptacles 44A and 44E indicated. They are located inside the control block 2 and accessible from the outside via mounting holes. The locking means 46, an M18 screw, can also be inserted and removed via these holes. Hole patterns with connection holes for the connections described in the description of the Figure 1 mentioned valves.

[0075] According to Figure 4 the receptacles 44A and 44E are visible in a cross-section of the control block.

[0076] Disclosed is a hydraulic control block with a generic hydraulic circuit structure for a selection of possible hydraulic cylinders and for controlling the pressure medium supply to the hydraulic cylinders, which is prepared in such a way that it is possible to change from one specific circuit structure to another by rearranging one of the means.

[0077] A hydraulic or servo-hydraulic axle is also disclosed. List of reference symbols:

[0078] 1 Hydraulic axis 2 Hydraulic control block 4 Hydraulic machine 6; 8 Hydraulic cylinder 10 First supply connection 12 First working flow path 14 Second supply connection 16 Second working flow path 18 Branch 20 Third working flow path 22 Valve 24 Filter 26 Safety valve 28 Branch 30A; 30E First working connection 32 Shut-off valve 34 Branch 36A; 36E Second working connection 38 Branch 40E Third working connection 42 Connecting flow path 44A, 44E Receptacle 46 Closure device 48 Accumulator flow path 50 Pressure relief valve 52 Hydraulic accumulator 54 Circulation valve nPiston area ratio

Claims

1. Hydraulic control block for controlling the supply of a pressure medium to a hydraulic cylinder (6; 8) of a hydraulic axle (1), wherein the control block (2) has a generic hydraulic switching structure from which, for selective supply of pressure medium to hydraulic cylinders (6; 8) differing in terms of their number of piston surfaces (n=2; n=3), specific hydraulic switching structures (A, B; E) are selectively configurable, having a first and a second supply interface (10, 14), the first (10) of which is fluidically connectable to a high-pressure side of a hydraulic machine (4) of the axle and the second (14) of which is fluidically connectable to a low-pressure side of the hydraulic machine (4), and vice versa, and having a first working flow path (12) which is fluidically connectable or connected to the first supply interface (10), having a second working flow path (16) which is fluidically connectable or connected to the second supply interface (14), and having a third working flow path (20) which is fluidically connectable or connected to the first supply interface (10) parallel to the first working flow path (12), wherein at least one first working connection (30A, 30E) branches off from the first working flow path (12), at least one second working connection (36A, 36E) branches off from the second working flow path (16) and at least one third working connection (40E) branches off from the third working flow path (20), and having a valve (22) in the third working flow path (20), via which the latter is selectively blockable or openable, and having a connecting flow path (42) via which the first working flow path (12) is fluidically connectable or connected to the third working flow path (20) in a portion of the third working flow path (20) between the valve (22) and the third working connection (40E), characterized by a releasably arrangeable or arranged closure means (46), via the selective arrangement of which and via an associated, at least sectional hydraulic closure of a flow path (12, 42) configured in the control block (2), one of the circuit structures (A, B; E) is configurable or configured, wherein the closure means (46) is releasably arrangeable or arranged so as to be accessible from outside the control block (2), and having a respective receptacle (44A, 44E) for a closure means (46) in the first working flow path (12) and in the connecting flow path (42), wherein the closure means (46) is optionally arranged in only one of the receptacles (44A, 44E), wherein, in a first configuration (A, B) of the circuit structures (A, B; E), the third working connection(s) (40E) are / is closed and the closure means (46) is arranged in the receptacle (44A) in the first working flow path (12), wherein the receptacle (44E) in the connecting flow path (42) is free, and wherein, in a second configuration (E) of the circuit structures (A, B, E), the receptacle (44A) in the first working flow path (12) is free and the closure means (46) is arranged in the receptacle (44E) in the connecting flow path (42).

2. Control block according to Claim 1, having a circulation flow path, via which the second working flow path (16) is fluidically connectable or connected to the third working flow path (20).

3. Control block according to Claim 1 or 2, wherein the working connections (30A, 36A; 30E, 36E, 40E) are fluidically connectable to a respective one of the piston surfaces, and / or wherein they are closable or closed.

4. Hydraulic axle having a control block (2) which is configured according to at least one of the preceding claims, and having a hydraulic machine (4) which is connected to the control block (2) and having a hydraulic cylinder (6; 8) which is connected to the control block, wherein a specific hydraulic switching structure (A, B; E) adapted at least to the number of piston surfaces (n=2; n=3) is configured from the generic circuit structure.

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