EP1085205B1 - Hydraulic drive - Google Patents

Abstract

The device has at least two pressure chambers (7) arranged between a stator (1) and a rotor (2), which are connected to at least partly separated hydraulic channels (11,19,22) at common hydraulic connections (20,23). The pressure chambers can be expanded, loaded and compresses alternately, so that the rotor moves with respect to the stator. A control device controls the hydraulic fluid flow. A check device (33,39) is provided in a section of hydraulic channel of at least one pressure chamber that is not part of the other pressure chamber. The flow of hydraulic fluid from the pressure chamber is prevented using the check device.

Description

The present invention relates to a hydraulic drive device, in particular a rotary device for excavator gripper and the like, with a stationary component and a moving component, in particular a stator and a rotor, at least two arranged between the fixed component and the moving component, at least partially separated hydraulic lines common hydraulic connections connectable pressure chambers which are alternately and successively pressurized with hydraulic fluid and thereby expandable and relieved and compressible via the hydraulic connections in such a way that moves the moving component relative to the stationary component, and a control device for controlling the supply and discharge of Hydraulic fluid in this way between the pressure chambers and the common hydraulic connections.

Such drive devices are known, for example, as axial or radial piston motors (see for example GB915231). But also vane motors and gear motors fall under this.

When using such drive devices as a rotating device for excavator gripper and the like, the problem arises that the gripper remains rotatable upon deactivation of the drive device. However, such twisting when the drive device is deactivated is in many cases undesirable. Therefore, brake devices are provided to prevent twisting of the gripper when the rotary device is deactivated.

For example, it is known to arrange a multi-disc brake between the stator and the rotor of the rotary device, in which disk-like pairs of brake disks can be pressed against one another to prevent rotation of the rotor relative to the stator. Of course, such braking devices add weight, and require extra space. When acting on friction brakes also has the problem that they are affected by pollution and wear in their function.

The invention has the object of providing a drive device of the type mentioned in such a way that these problems do not occur. In particular, the drive device should be equipped with a braking device that is as light as possible and takes up little space. In addition, the braking device should be as reliable as possible.

This object is achieved in that a shut-off device is provided in a portion of the hydraulic line of at least one pressure chamber, which it does not share with the other pressure chambers, through which a drainage of hydraulic fluid from the pressure chamber is prevented.

By locking the hydraulic line, the hydraulic fluid remains trapped in the pressure chamber. Since hydraulic fluid is virtually incompressible, further rotation of the drive device is prevented in the Ideally completely blocked. Preferably, a shut-off device is provided on at least two pressure chambers, which are pressurized in diametrically opposite phases. This ensures that the braking effect occurs regardless of the position of the moving component immediately. It is also possible to provide all pressure chambers with a shut-off device in order to further improve the braking effect.

The braking device according to the invention is basically used in all types of drive devices of the type mentioned, such as axial and radial piston drives, vane drives and gear drives. The control device can also be designed in various ways, for example as a plan distributor or radial distributor. But also an electrical or electronic control device in conjunction with a path or angle measuring is possible. It is essential that the shut-off devices are arranged in the separate sections of the hydraulic lines of the pressure chambers, so that when closing the shut-off device, an exchange of hydraulic fluid between the individual pressure chambers is prevented. In addition, the invention can be used both with endlessly rotatable drive devices and with drive devices which can only be rotated to a limited extent, and in principle also with translationally moved drive devices.

According to one embodiment of the invention, the shut-off device is automatically controlled in dependence on the operating state of the drive device. This ensures that the shut-off automatically opens upon actuation of the drive device and locks when stopping the drive device.

According to a further embodiment of the invention, the shut-off device can be unlocked directly via the drive pressure of the hydraulic fluid. This can be done in a structurally inexpensive way a control of the shut-off device in dependence on the operating state of the drive device.

According to a further embodiment of the invention, the pressure chambers are each formed as a piston pressure chamber of a piston-cylinder arrangement which is fixedly connected to one of the two elements, moving component and stationary component, and whose piston is supported via a rolling body on the other element. Such an arrangement is, for example, a radial piston drive or an axial piston drive, which have proven to be particularly advantageous as a rotating device for excavator grippers and the like.

According to a further embodiment of the invention as a rotating device with rotor and stator, a curved path is rotatably connected to the other element, on which run the rolling body of the piston. As a result of the alternating pressurization of the pressure chambers, the pistons are cyclically loaded in such an arrangement such that the piston and the curved path are continuously rotated in one direction relative to one another. In this case, the curved path can be arranged on the rotor or on the stator. Accordingly, the pistons with the other element, ie stator or rotor, rotatably connected. Such a configuration has the advantage that the rotor has a fixed axis of rotation.

According to a further embodiment of the invention, the pistons are provided with sealing rings, in particular piston seals. This prevents that hydraulic fluid can escape through the annular gap between the piston and cylinder from the piston pressure chamber, so that a complete blockage of the drive device is made possible.

According to a further embodiment of the invention as a rotating device with rotor and stator, the control device is designed as a radial distributor, with a circular cross-section having distributor cylinder and a corresponding circular cylindrical manifold receptacle in which the distributor cylinder is rotatably guided, wherein the distributor cylinder with one of the two elements, stator and rotor, rotatably connected and the receptacle is arranged in the other element, and wherein the mutually separated sections of the hydraulic lines of the pressure chambers open into the manifold receptacle and alternately depending on the relative rotational position of the distributor cylinder and distributor receptacle on existing in the lateral surface of the distributor cylinder recesses and successively with a first annular groove provided in the distributor receptacle, which is connected to a first hydraulic connection, and a second, which is likewise seen in the receiving device Ring groove, which is connected to a second hydraulic connection, are connected. The two hydraulic connections serve to supply and discharge of hydraulic fluid to the drive device, wherein the direction of rotation of the device can be selected by changing the use of the connections for the supply and the discharge.

The use of such a radial distributor has proven itself in practice. Distribution cylinder and distributor intake are such Device automatically rotated with the rotation of the rotor against each other and thereby control the supply and discharge of hydraulic fluid between the individual pressure chambers and the hydraulic connections via the opening into the manifold receiving individual hydraulic lines. The control is done in a cost effective and safe way.

According to a further embodiment of the invention, the radial distributor is in the receptacle between a first position in which the portion of the hydraulic line at least one pressure chamber, which it does not have in common with the other pressure chambers, is closed, and a second position in which it is open , axially movable. Due to the axial displaceability of the radial distributor, the operation of the shut-off devices for braking the drive device can be realized in a simple manner.

In particular, according to a further embodiment of the invention, the sections of the hydraulic lines are closed in the first position of the radial distributor by the lateral surface of the distributor cylinder, while they are connected in the second position via the recesses in the lateral surface with the first or the second annular groove. The shut-off takes place in this embodiment so on the sliding fit of the distributor cylinder in the recording. Thus, at least one braking effect, although due to the leakage of hydraulic fluid between the distributor cylinder and recording no complete blockage can be achieved.

According to a further embodiment of the invention is in a portion of the hydraulic line at least one pressure chamber, this not with the other pressure chambers in common, each having a shut-off valve which is adjustable against the force of a return spring via a plunger in an open position, which plunger is guided in a recess opening into the receptacle of the radial distributor and is supported on the lateral surface of the distributor cylinder, wherein in the lateral surface is provided with an annular groove, in which the plunger engages in the first axial position of the distributor cylinder with its free end, so that the shut-off valve is closed, while the plunger is held in the open position in the second axial position of the distributor cylinder by its lateral surface. By such shut-off valves a complete blockage of the hydraulic lines is possible. In particular, in conjunction with the piston sealing rings, a complete blocking of the rotating device can be achieved. Hydraulic fluid can not escape between the distributor cylinder and distributor intake, nor between the piston and cylinder from the pressure chambers of the blocked pistons.

According to a further embodiment of the invention, the distributor cylinder has an axial Druckanstellfläche to control its axial displacement. The axial displacement of the distributor cylinder is thereby made possible in a simple manner.

In particular, the pressure contact surface of the distributor cylinder can be acted upon by drive pressure oil. Thus, the distributor cylinder can be automatically moved axially upon actuation of the drive device and the braking device thereby be solved. External control is also possible.

Instead of an axial displaceability of the distributor cylinder, an axially displaceable sleeve can also be provided, which comprises the distributor and locks the hydraulic lines opening into the receptacle in an axial position and releases them in the other axial position.

A particular advantage of the embodiment with axially displaceable distributor cylinder is also that the drive device can be constructed identical with and without brake device. In the variant without braking device only the distributor cylinder must be correspondingly formed axially longer, or it must be provided a suitable spacer to prevent axial displacement of the distributor cylinder.

According to a further embodiment of the invention, a pilot-operated check valve is arranged in a section of the hydraulic line at least one pressure chamber, which does not have this in common with the other pressure chambers. In this embodiment, the flow of hydraulic fluid through the hydraulic lines is thus not controlled via the distributor cylinder. Instead, check valves are provided in the hydraulic lines, through which the pressure chambers are closed due to the existing hydraulic pressure there, when the check valves are not unlocked. This also makes complete blocking of the drive device possible.

The unlocking of the check valves is carried out according to a further embodiment of the invention preferably via the drive pressure oil. This again ensures that the braking device upon actuation of the drive device automatically resolved. External control is also possible.

According to a further embodiment of the invention, a pressure limiting valve is arranged in at least one pressure chamber. This prevents damage to the drive device when too large a torque acts on the moving component when the drive device is locked. Preferably, a pressure relief valve is provided in all pressure chambers. As a result, damage to the drive device can be prevented particularly effectively.

Fig. 1

einen Querschnitt durch eine erste Variante der erfindungsgemäßen Antriebsvorrichtung,

Fig. 2

einen Querschnitt durch eine zweite Variante der erfindungsgemäßen Antriebsvorrichtung und

Fig. 3

einen Querschnitt durch eine dritte Variante der erfindungsgemäßen Antriebsvorrichtung.

Embodiments of the invention are illustrated in the drawings and will be described below. They show, in each case in a schematic representation,

Fig. 1

a cross section through a first variant of the drive device according to the invention,

Fig. 2

a cross section through a second variant of the drive device according to the invention and

Fig. 3

a cross section through a third variant of the drive device according to the invention.

The hydraulic drive device shown in Fig. 1 comprises a stator 1, which is connectable, for example, with an excavator boom, not shown, and a rotatably mounted on the stator about an axis I. Rotor 2, on which, for example, a digging grab, also not shown, can be fastened. But stator 1 and rotor 2 can also be mounted vice versa, so that the stator 1 to the rotor and the rotor 2 to the stator. The drive acting between stator 1 and rotor 2 comprises a plurality of piston-cylinder arrangements 3 arranged radially in relation to the axis of rotation I in the stator 1. The cylinders of the piston-cylinder arrangements 3 are each formed by a recess 4 of circular cross-section in the stator 1 in which a piston 5 is displaceably guided in the radial direction. Between the radially inner base 6 of the recess 4 and the piston 5, a piston pressure chamber 7 is formed in each case. In this piston pressure chamber 7 each have a compression spring 8 is arranged, which is supported on the base 6 of the recess 4 and the piston 5 urges radially outward.

On the side facing away from the piston pressure chamber 7 side of the piston 5, a roller-shaped rolling body 9 is provided in each case, which is rotatably mounted on the piston 5 about an axis II parallel to the axis II on the piston 5. By acting on the piston 5 compression spring 8 of the rolling body 9 is urged against a cam track 10 which is provided on the rotor 2, the piston 5 opposite. The distance of the cam track 10 from the rotation axis I changes cyclically around the rotation axis I between a maximum distance in which the piston 5 is extended, and a minimum distance in which the piston 5 is retracted.

The piston pressure chamber 7 of the piston-cylinder assemblies 3 is in each case via a hydraulic channel 11 with a provided in the stator 1 central recess 12 in connection whose free cross-section substantially the shape of a extending in the direction of the axis I circular cylinder has and which serves as a distributor receptacle. In this receptacle 12, a distributor cylinder 13 is also used with a substantially circular cross section, which is rotatably supported by the receptacle 12 about the rotation axis I and slidably guided between a first axial position and a second axial position. The first axial position of the distributor cylinder 13 is determined by the bottom 14 of the receptacle 12, the second axial position by the rotor 2, which is rotatably connected to the stator 1 about the axis I. About a engaging in an end-side recess 15 of the distributor cylinder 13 entrainment pin 16 of the distributor cylinder 13 is rotatably connected to the rotor 2.

In the inner peripheral surface 17 of the receptacle 12, a first annular groove 18 is introduced, which is connected via a hydraulic channel 19 with a first hydraulic connection 20. Furthermore, in the inner peripheral surface 17 of the receptacle 12, a second annular groove 21 is introduced, which is connected via a hydraulic passage 22 with a second hydraulic connection 23. To the hydraulic connections 20 and 23, for example, coming from an excavator boom forth hydraulic lines are connected, which serve for the supply and discharge of hydraulic fluid. About recesses 24 in the cylinder jacket surface 25 of the distributor cylinder 13 leading to the piston pressure chambers 7 hydraulic channels 11 are alternately connected in succession with one annular groove 18 and the other annular groove 21 in dependence on the rotational position of the distributor cylinder 13. In this way, the pressure chambers 7 are applied alternately with hydraulic pressure oil and relieved.

When loading a pressure chamber 7 by supplying hydraulic fluid via the first hydraulic port 20, channel 19, annular groove 18, a recess 24 and the associated hydraulic channel 11, the piston 5 of the associated piston-cylinder assembly 3 is urged radially outward. As a result, the rolling body 9 of this piston-cylinder arrangement 3 on the curved path 10 down the slope, that is radially moved to the outside, so that the piston 5 can extend radially. That is, since the cam track 10 is mounted on the rotor 2, the cam track 10 moves with the rotor 2 corresponding to the rotation axis I. After reaching a valley of the cam track 10 of the hydraulic channel 11 is connected via the next recess 24 with the other annular groove 21 , which is connected via the channel 22 to the second hydraulic port 23. Now, the piston 5 can retract radially into the recess 4 and the rolling body 9 on the curved path 10 uphill, so roll radially inward. As a result, the rotor 2 continues to rotate in the same direction about the axis of rotation I. Accordingly, the pressure chambers 7 of the other piston-cylinder assemblies 3 are alternately acted upon and relieved with hydraulic fluid, so that a continuous movement. By interchanging supply and discharge of the hydraulic fluid via the ports 20 and 23, the direction of rotation of the device can be reversed.

The distributor cylinder 13 has a pressure contact surface 26 which is directed transversely to the axis of rotation I and can be acted upon by drive pressure via an annular space 27 formed between distributor cylinder 13 and distributor receptacle 12, which can be connected to the hydraulic fluid supply via a hydraulic channel 28. A changeover valve 29 ensures that the annular space 27 is acted upon by hydraulic fluid in both directions of rotation of the device.

Upon application of the annular space 27 with hydraulic fluid, the distributor cylinder 13 is moved axially against the force of a restoring spring 30 in the direction of the rotor 2. Upon relief of Druckanstellfläche 26, the distributor cylinder 13 moves away under the force of the return spring 30 from the rotor 2 until the distributor cylinder 13 abuts the bottom 14 of the receptacle 12. This position is shown in Fig. 1. It remains between the distributor cylinder 13 and receptacle 12, a small annular space 27, via which the distributor cylinder 13 can be acted upon again with hydraulic fluid.

While in the second position of the distributor cylinder 13, not shown here, the recesses 24 each connect an annular space 18 or 21 to the hydraulic channels 11 of the piston-cylinder assemblies 3, in the first axial position of the distributor cylinder 13 shown in FIG , Rather, the recesses 24 are connected only to the annular channel 18 or only to a hydraulic channel 11. The annular groove 21 and a part of the hydraulic channels 11, however, is closed by the lateral surface 25 of the distributor cylinder 13. As a result, no hydraulic fluid can flow out of the piston pressure chambers 7. It only occurs a certain leakage between distributor cylinder 13 and receptacle 12. However, the rotor is braked against rotation relative to the stator 1, since the pistons 5 can not or only very slowly enter the recesses 4 according to the amount of leakage.

In order to avoid damage to the drive device when an excessive torque acts on the rotor 2 when the drive device is blocked, one piston piston 5 is in each case connected to the piston pressure chamber 7 connected and in the low pressure space 31 between the rotor 2 and stator 1 opening pressure relief valve 32 is provided.

The variant shown in Fig. 2 is consistent with the variant of FIG. 1 largely. In contrast to this first variant, however, in each case a shut-off valve 33 is arranged in the hydraulic channels 11 between the piston pressure chamber 7 and receptacle 12, which is displaceable via a plunger 34 against the force of a return spring 35 in the open position. The plunger 34 is guided in a recess 36 between the hydraulic channel 11 and receptacle 12 and is supported by its free end 37 on the cylinder jacket surface 25 of the distributor cylinder 13 from. In addition, in the cylinder jacket surface 25 of the distributor cylinder 13, an annular groove 38 is introduced, in which the plunger 34 can retract with its free end 37 when the distributor cylinder 13 is in its position remote from the rotor 2. This situation is shown in the left half of FIG. In this retracted into the annular groove 38 position of the plunger 34, the shut-off valve 33 is closed, while it is opened in axial displacement of the distributor cylinder 13 in the direction of the rotor 2 by moving the plunger 34 via the lateral surface 25 of the distributor cylinder 13. This situation is shown in the right half of FIG.

As before, thus the hydraulic channels 11 between the piston pressure chambers 7 and the receptacle 12 in the first axial position of the distributor cylinder 13, in which it is not acted upon by the drive pressure, closed, while in the second axial position of the distributor cylinder 13, in which this is acted upon by the drive pressure, depending on the rotational position of the distributor cylinder 13 either with the first annular groove 18 or with the second annular groove 21 via the recesses 24 in the cylinder jacket surface 25 of the distributor cylinder 13 are connected. In contrast to the previous variant, however, the closure of the cylinder pressure chambers 7 due to the use of the shut-off valves 33 is absolutely tight, so that from the piston pressure chambers 7 and no leakage liquid can escape. The rotating device is thereby completely blocked. In this variant, too, however, the pistons 5 have pressure-limiting valves 32 which open in the low-pressure space 31 between the stator 1 and the rotor 2 in order to prevent damage to the drive device due to an excessive force on the rotor 2.

In the variant illustrated in FIG. 3, the drive basically agrees with the two previous variants. However, the distributor cylinder 13 is not axially displaceable here. Instead, in each case a pilot-operated check valve 39 is arranged in the hydraulic lines 11 between the piston pressure chambers 7 and the receptacle 12, through which the piston pressure chambers 7 are completely shut off. The unlocking of the check valves 39 via the drive pressure with which the check valves 39 are acted upon by hydraulic channels 40, which in turn, are connected to the shuttle valve 29, so that an unlocking of the check valves 39 takes place in both directions of rotation of the drive device. Upon actuation of the drive device so all check valves 39 are unlocked, so that the piston pressure chambers 7 of the piston-cylinder assemblies 3 are connected via the hydraulic channels 11 each with either the first annular space 18 or the second annular space 21, depending on the rotational position of the distributor cylinder 13, so that the piston pressure chambers 7 cycle either loaded with hydraulic fluid or relieved.

While the first variant of the drive device according to the invention acts as a brake, the second and third variants lead to a blocking of the drive device. Depending on requirements, one or the other variant can be selected. In any case, the brake or Blokkiereinrichtung is structurally inexpensive, little space consuming and light. In addition, it is reliable. In particular, no functional impairment occurs due to contamination and wear.

LIST OF REFERENCE NUMBERS

1

stator

2

rotor

3

Piston-cylinder arrangement

4

recess

5

piston

6

Reason of 4

7

Piston pressure chamber

8th

Return spring

9

unwinding

10

cam track

11

hydraulic channel

12

admission

13

distributor cylinder

14

Reason of 12

15

Recess in 13

16

Carrier pin

17

Inner peripheral surface of 12

18

first ring groove

19

hydraulic channel

20

first hydraulic connection

21

second annular groove

22

hydraulic channel

23

second hydraulic connection

24

Recess in 25

25

Lateral surface of 13

26

Druckanstellfläche

27

annulus

28

hydraulic channel

29

shuttle valve

30

Return spring

31

Low-pressure chamber

32

Pressure relief valve

33

shut-off valve

34

tappet

35

Return spring

36

recess

37

free end of 34

38

ring groove

39

unlockable check valve

40

hydraulic channel

I

Rotation axis of 2

II

Rotation axis of 9

Claims (12)

1. A hydraulic drive apparatus, in particular a rotary apparatus, for excavator grabs and the like, having a fixed component (1) and a moved component (2), in particular a stator (1) and a rotor (2), at least two pressure chambers (7) which are arranged between the fixed component (1) and the moved component (2), which can be connected via hydraulic lines (11, 19, 22), which are separated from one another at least sectionally, to common hydraulic connections (20, 23) and which can be pressurised with hydraulic fluid alternately and sequentially via the hydraulic connections (20, 23), and can thereby be expanded, relieved and compressed, such that the moved component (2) moves relative to the fixed component (1), and having a control device for the control of the inflow and outflow of the hydraulic fluid in this manner between the pressure chambers (7) and the common hydraulic connections (20, 23), wherein a shut-off device (33, 39) is provided in a section (11) of the hydraulic line of at least one pressure chamber (7) which the pressure chamber (7) does not have in common with the other pressure chambers (7), characterised in that the shut-off device (33, 39) prevents an outflow of hydraulic fluid from the pressure chamber (7).
2. A drive apparatus in accordance with claim 1, characterised in that the shut-off apparatus (33, 39) can be controlled automatically in dependence on the operating state of the drive apparatus, with the shut-off device (33, 39) in particular being able to be released directly via the drive pressure of the hydraulic fluid.
3. A drive apparatus in accordance with any one of the preceding claims, characterised in that the pressure chambers (7) are each configured as a piston pressure space of a piston-in-cylinder arrangement (3) which is fixedly connected to one of the two elements, fixed component (1) and moved component (2), and whose piston (5) is supported at the other element via a roll-off member (9).
4. A drive apparatus in accordance with claim 3, characterised in that it is configured as a rotary device having a stator (1) and a rotor (2); and in that a cam track (10) is rotationally fixedly connected to the other element and the roll-off members (9) of the pistons (5) run thereon.
5. A drive apparatus in accordance with claim 3 or claim 4, characterised in that the pistons (5) are provided with sealing rings, in particular with piston seals.
6. A drive apparatus in accordance with any one of the preceding claims, characterised in that it is configured as a rotary apparatus having a stator (1) and a rotor (2); and in that the control device is configured as a radial distributor, with a distributor cylinder (13) having a circular cross-section and a correspondingly circular-cylindrical recess (12) in which the distributor cylinder (13) is rotatably guided, with the distributor cylinder (13) being rotationally fixedly connected to one of the two elements, stator (1) and rotor (2), and the recess (12) being provided in the other element, and with the sections (11) of the hydraulic lines of the pressure chambers (7) separate from one another opening into the recess (12) and being connected alternately and sequentially in dependence on the relative rotary position of the distributor cylinder (13) and the recess (12) via cut-outs (24) present in the jacket surface (25) of the distributor cylinder (13) to a first ring groove (18) which is provided in the recess (12) and is connected to a first hydraulic connection (20) and to a second ring groove (21) which is likewise provided in the recess (12) and is connected to a second hydraulic connection (23).
7. A drive apparatus in accordance with claim 6, characterised in that the distributor cylinder (13) is axially displaceable in the recess (12) between a first position in which a section (11) of the hydraulic line of at least one pressure chamber (7), which the pressure chamber (7) does not have in common with the other pressure chambers (7), is closed and a second position in which it is open.
8. A drive apparatus in accordance with claim 7, characterised in that the sections (11) of the hydraulic lines are closed by the jacket surface (25) of the distributor cylinder (13) in the first position, whereas they are in each case connected in the second position either to the first ring groove (18) or to the second ring groove (21) via the cut-outs (24) in the jacket surface (25) of the distributor cylinder (13).
9. A drive apparatus in accordance with claim 7, characterised in that a respective shut-off valve (33) is arranged in a section (11) of the hydraulic line of at least one pressure chamber (7) which it does not have in common with the other pressure chambers (7), said shut-off valve being adjustable via a plunger (34) against the force of a restoring spring (35) into an open position, said plunger (34) being guided in a cut-out 36 opening into the recess (12) of the radial distributor and being supported on the jacket surface (25) of the distributor cylinder (13), with a ring groove (38) being provided in the jacket surface (25) into which the free end (37) of the plunger (34) can move in the first axial position of the distributor cylinder (13) so that the shut-off valve (33) is closed, whereas the plunger (34) is held in the open position in the second axial position of the distributor cylinder (13) by the latter's jacket surface (25).
10. A drive apparatus in accordance with any one of the claims 7 to 9, characterised in that the distributor cylinder (13) has an axial pressure application surface (26) for the control of its axial displacement, with the pressure application surface (26) preferably being able to be acted on by drive pressure oil.
11. A drive apparatus in accordance with any one of the claims 1 to 6, characterised in that a respective releasable check valve (39) is arranged in a section (11) of the hydraulic lines of at least one pressure chamber (7) which it does not have in common with the other pressure chambers, with the check valves (39) preferably being releasable via the drive pressure oil.
12. A drive apparatus in accordance with any one of the preceding claims, characterised in that a pressure restricting valve (31) is arranged in at least one pressure chamber (7) and opens into a low-pressure space (31) of the drive apparatus.

Images