Hydraulic system for a rotor brake, rotor brake and wind turbine

Abstract

The present invention relates to a hydraulic system 10 for a rotor brake 1 of a wind turbine, wherein the hydraulic system 10 comprises a pressure chamber 11, a manually operated pump unit 12, and a connection 13 for connection to the rotor brake 1, the manually operated pump unit 12 being connected to the pressure chamber 11 and the connection 13. The manually operated pump unit 12 has a coupling section 27 for actuation, wherein the coupling section 27 is connectable to an external device.

Description

[0001] The present invention relates to a hydraulic system for a rotor brake of a wind turbine. Furthermore, the present invention relates to a rotor brake having such a hydraulic system and a brake caliper. Furthermore, the present invention also relates to a wind turbine having a rotor brake according to the invention.

[0002] Common wind turbines are typically equipped with a rotor brake. During maintenance, the brake is applied to prevent unwanted and potentially dangerous movement of the wind turbine's rotor. For this purpose, the rotor brake typically has at least one brake caliper, which usually acts on a brake disc mounted on the generator shaft to lock the generator shaft.

[0003] The use of a hydraulic system has proven effective for applying the rotor brake. These state-of-the-art hydraulic systems comprise a hydraulic unit to supply pressure to the rotor brake, along with the necessary pressure relief valves, pressure switches, and changeover valves. The operating pressure of the rotor brake is provided by operating the hydraulic unit in accumulator-charging mode. After the maintenance procedure is completed, the hydraulic unit is shut down, releasing the rotor brake. Such a hydraulic system is known, for example, from DE 10 2007 002 137 A1. DE 10 2017 102 375 B3 shows a hydraulic system for a rotor brake with a manually operated emergency brake pump.

[0004] These well-known solutions function reliably and are easy to operate by a maintenance technician. However, the disadvantage of these solutions is the large number of relatively expensive components. Especially considering the reduced time required for the hydraulic unit, it is desirable to provide a significantly more cost-effective solution.

[0005] It is therefore the object of the present invention to provide a more cost-effective hydraulic system for a rotor brake of a wind turbine.

[0006] The problem is solved with a hydraulic system for a rotor brake of a wind turbine according to claim 1. Advantageous further developments are described in the dependent claims.

[0007] The hydraulic system according to the invention for a rotor brake of a wind turbine comprises a manually operated pump device and a connection for connection to the rotor brake. The manually operated pump device is connected to the connection. Thus, no expensive hydraulic unit is required. Instead, the required operating pressure of the rotor brake is provided via a cost-effective manually operated pump device.

[0008] According to the invention, the manually operable pump device has a coupling section for actuation, wherein the coupling section can be connected to an external device. In other words, the coupling section is designed such that an external device can be connected to the coupling section. The maintenance technician can thus actuate the pump device accordingly via the external device connected to the coupling section and generate the necessary operating pressure.

[0009] A connection within the meaning of the invention does not necessarily refer to a single connection. Rather, it can also refer to multiple connections and additional connections, for example, connection options for leakage lines or the like.

[0010] It is advantageous if the hydraulic system also has a tank chamber, which is connected to the manually operated pump element. The tank chamber can serve, for example, to compensate for temperature fluctuations.

[0011] The hydraulic system according to the invention preferably has a first bypass line, wherein the first bypass line connects the connection to the tank chamber, bypassing the manually operable pump device. A first closing valve can be arranged in the first bypass line. In particular, the first closing valve can be a pressure relief valve or a shut-off valve.

[0012] A shut-off valve designed as a pressure relief valve can provide protection against excessive pressure. If the shut-off valve is designed as a manually opened shut-off valve, the maintenance technician can directly regulate the pressure at the connection, for example, to compensate for temperature fluctuations.

[0013] In this context, it is advantageous if the hydraulic system has a second bypass line, wherein the second bypass line connects the connection to the tank chamber, bypassing the manually operable pump device. A second closing valve can be arranged in the second bypass line. Preferably, the second closing valve is either a pressure-limiting valve or a preferably manually opened shut-off valve and is different from the first closing valve. In other words, if the first closing valve is designed as a pressure-limiting valve in a preferred embodiment, the second closing valve is designed as a shut-off valve.

[0014] The hydraulic system is preferably designed as a cartridge. This screw-in cartridge design allows for particularly easy installation and integration.

[0015] It is advantageous if the hydraulic system is hydraulically preloaded, preferably via a spring preload integrated into the manually operated pump unit or an integrated hydraulic accumulator. This allows temperature fluctuations and minor leaks in the brake caliper to be directly compensated. It is conceivable that the tank compartment could be designed as a hydraulic accumulator.

[0016] Conveniently, the external device that can be connected to the coupling section is a tool or an external motor. The maintenance technician can then operate the pumping device using a tool and generate the necessary operating pressure. The tool can also be attached to a cordless screwdriver or similar device, for example. The use of an external motor is also conceivable to provide the operating pressure via the manually operated pumping device. This results in a particularly easy-to-operate hydraulic system for providing the operating pressure required to apply the brake.

[0017] It is advantageous if the manually operable pump device comprises a pressure chamber, a housing, a drive shaft, and a piston element, wherein the pressure chamber is at least partially formed by the housing. The piston element is movably arranged in the pressure chamber, and the drive shaft is rotatably mounted relative to the housing and connected to the piston element. Rotation of the drive shaft moves the piston element linearly or axially in the pressure chamber and thus relative to the housing. When the maintenance technician rotates the drive shaft, the piston element moves linearly in the pressure chamber to generate the required operating pressure.

[0018] It is advantageous if the piston element is guided within the housing in such a way that rotation of the piston element relative to the housing is prevented. The drive shaft is thus rotatable relative to the housing, but not axially or linearly movable. A rotational movement of the drive shaft is thus transmitted to the piston element via a suitable interface, for example, via a threaded connection between the drive shaft and the piston element.

[0019] Alternatively, it is advantageous if the drive shaft is axially movable relative to the housing and moves together with the piston element. When the drive shaft rotates, it moves axially relative to the housing, resulting in a rising drive shaft. This has the advantage that a separate bearing to support the rotational movement of the drive shaft, such as a rolling or plain bearing, is not required.

[0020] Such a fully integrated hydraulic system can be arranged directly on the brake caliper or used as a stand-alone solution.

[0021] Preferably, the piston element comprises a first piston part, a second piston part, and a preloading element, wherein the first piston part is connected to the drive shaft and the second piston part is connected to the first piston part via the preloading element. The preloading element can be used to achieve hydraulic preload of the hydraulic system, for example, to compensate for minor leaks in the brake caliper or temperature fluctuations.

[0022] It is advantageous if the manually operated pump device has a locking element that can be moved between a release position and a locking position. The locking element fixes the drive shaft in the locking position, preventing it from rotating relative to the housing. In the release position of the locking element, the drive shaft can rotate relative to the housing. Thus, by moving the locking element from the release position to the locking position, the maintenance technician can reliably prevent further rotation of the drive shaft and thus also prevent a change in the operating pressure.

[0023] Alternatively, it may be advantageous if the manually operable pump device is a gear pump with a drive shaft, wherein the coupling portion is arranged on the drive shaft. Preferably, the coupling portion is arranged at an axial end of the drive shaft of the gear pump.

[0024] Due to the potential for leakage at the gear pump, it is advisable to install a manually releasable check valve between the gear pump and the connection. The manually releasable check valve prevents backflow from the connection to the gear pump, thus trapping pressure between the check valve and the connection or a brake caliper connected to the connection, thus holding the brake caliper in the extended position. To retract the brake caliper, the manually releasable check valve is manually released.

[0025] It is advantageous if the hydraulic system has a manually operated lever mechanism for unlocking the check valve. For example, the lever mechanism could be designed as a button or a lever.

[0026] It is particularly advantageous if the manually operable lever mechanism is connected to the drive shaft of the gear pump, whereby an axial movement of at least part of the drive shaft actuates the lever mechanism and releases the check valve. This allows the maintenance technician to axially displace the entire drive shaft or part of it, for example, using an external device attached to the coupling section, for example by pushing it in. This unlocks the check valve, and a rotation of the drive shaft applies pressure to the connection or relieves pressure from it, depending on the direction of rotation.

[0027] It is advantageous if the manually operated pump device is a reversible manually operated pump device. This allows the operating pressure applied to the connection to be reduced by reversing the direction of rotation of the drive shaft.

[0028] The invention further relates to a rotor brake for a wind turbine, wherein the rotor brake comprises at least one brake caliper and a hydraulic system according to the invention as described above, wherein the brake caliper is hydraulically connected to the connection of the hydraulic system. Furthermore, the invention relates to a wind turbine having such a rotor brake.

[0029] The invention will be explained in more detail below with reference to exemplary embodiments shown in the drawings. These schematically show: Fig. 1 a side view of a wind turbine: Fig. 2 shows a hydraulic circuit diagram of a rotor brake with a hydraulic system according to the invention according to a first embodiment; Fig. 3 shows an exemplary structural design of a hydraulic system according to the invention according to the first embodiment; Fig. 4 shows an alternative exemplary structural design of a hydraulic system according to the invention according to the first embodiment; Fig. 5 shows a hydraulic circuit diagram of a hydraulic system according to the invention according to a second embodiment; and Fig. 6 a hydraulic circuit diagram of an alternative embodiment of the Fig. 5 shown hydraulic system according to the invention according to the second embodiment.

[0030] Fig. 1 shows a schematic side view of a wind turbine 100. The wind turbine 100 has a tower 102 and a nacelle 104 attached to the tower 102. A rotor 106 is rotatably mounted on the nacelle 104. The wind turbine 100 further comprises a plurality of rotor blades 108 attached to the rotor 106. Furthermore, the wind turbine includes a pitch system (not shown) configured to adjust the aerodynamic angle of attack of one or all of the rotor blades 108 of the wind turbine 100 based on the environmental conditions. The pitch system changes the angle of attack of the rotor blades 108 depending on the current wind speed in order to operate the wind turbine 100 with the best possible efficiency and thus with a largely constant rated power. For this purpose, the rotor blades 108 are adjusted in their angular position relative to the rotor 106 via the pitch system so that the best possible lift is generated.The pitch system is further designed to prevent damage to the wind turbine 100 in strong winds by rotating the rotor blades 108 into the wind. The rotor blades 108 also assume a corresponding position during upcoming maintenance. This interrupts the lift of the rotor blades 108 and causes the rotor 106 to come to a standstill.

[0031] In order to prevent the rotor 106 from starting up again, which could be dangerous, during maintenance of the wind turbine 100, the rotor can be locked by means of a rotor brake 1.

[0032] In Fig. Figure 2 shows a hydraulic circuit diagram of a rotor brake 1 according to the invention. The rotor brake 1 comprises a hydraulic system 10 according to a first embodiment, a brake caliper 2, and a brake element (not shown), for example, a disc brake. The hydraulic system 10 generates the operating pressure required to lock the rotor 106, which is applied to the brake caliper 2 and thus closes the brake.

[0033] The hydraulic system 10 has a tank chamber 30, a manually operated pump device 12 with a pressure chamber 11, and a connection 13. During maintenance of the wind turbine 100, the maintenance technician can generate the necessary operating pressure of the rotor brake 1 via the manually operated pump device 12. For this purpose, the brake caliper 2 is connected to the connection 13 of the hydraulic system 100 via a line 3 in a known manner.

[0034] Furthermore, the hydraulic system 10 has a first bypass line 14 with a first closing valve 15 designed as a pressure relief valve. Furthermore, the hydraulic system 10 can have a second bypass line 16 with a second closing valve 17 designed as a shut-off valve. The first bypass line 14 and the second bypass line 16 each connect the connection 13 directly to the tank chamber 30, bypassing the manually operable pump element 12. The pressure relief valve 15 protects the hydraulic system 10 in the event of an excess pressure. The shut-off valve 17 is designed as a manually opened shut-off valve, allowing the maintenance technician to reduce the pressure applied to the brake caliper 2 if necessary, for example, in the event of temperature fluctuations.

[0035] Fig. 3 shows an exemplary structural design of a hydraulic system 10 according to the invention in accordance with the first embodiment. The manually operable pump element 12 has a housing 18, a drive shaft 19, and a piston element 20. The piston element 20 comprises a first piston part 21, a second piston part 22, and a preloading element 23. The pressure chamber 11 is at least partially formed by the housing 18. The piston element 20 is arranged to be linearly movable within the pressure chamber 11 or the housing 18 in order to change the volume of the pressure chamber 11 and thus to provide the operating pressure at the connection 13. The preloading element 23 is supported on the first piston part 21 and the second piston part 22 and thus hydraulically preloads the hydraulic system 10, for example, to compensate for minor leaks at the brake caliper 2.

[0036] As shown, the connection 13 is formed on an axial end face of the housing 18, and the line 3 is secured to the connection 13, for example, by screwing. Of course, the line 3 can also be secured to the connection 13 in other ways.

[0037] The drive shaft 19 is rotatably mounted on the housing 18 via at least one bearing 24, wherein the drive shaft 19 is axially immobile relative to the housing 18. For this purpose, the housing 18 can, for example, have an intermediate plate 25, on which the drive shaft 19 is axially supported via a circumferential ring 31 (indirectly via the bearing 24) and is thus secured against axial movement or axial displacement. Of course, the drive shaft 19 can also be secured against axial movement in other ways.

[0038] The drive shaft 19 is connected to the piston element 20 such that a rotary movement of the drive shaft 19 is converted into a linear movement of the piston element 20. In the illustrated embodiment, the drive shaft 19 is connected to the first piston part 21 via a threaded connection 26. The first piston part 21 is guided within the housing 18 such that rotation of the first piston part 21 relative to the housing 18 is prevented. This can be achieved, for example, via a grooved guide (not shown). Of course, other anti-rotation devices are also conceivable.

[0039] By rotating the drive shaft 19, the first piston part 21 is moved relative to the drive shaft 19 and thus to the housing 18 due to the threaded connection 26. The linear movement of the first piston part 21 is transmitted to the second piston part 22 via the preloading element 23, and depending on the direction of rotation of the drive shaft 19, the volume of the pressure chamber 11 is thus increased or decreased. The manually operated pump element is therefore a reversible manually operated pump element. By reversing the direction of rotation of the drive shaft 19, the operating pressure present at port 13 can be reduced.

[0040] Alternatively, the drive shaft 19 can also be designed with a rising shaft. The drive shaft 19 is then rigidly connected to the piston element 20 or the first piston part 21 and moves axially and relative to the housing 18 upon rotation. This has the advantage that the bearing 24 can be omitted and the first piston part 21 does not need to be secured against rotation.

[0041] A coupling section 27 is arranged at the axial end of the drive shaft 19 opposite the threaded connection 26. A suitable external device, such as a tool, can engage the coupling section 27 to rotate the drive shaft 19. For example, the coupling section 27 can be designed as a hexagon, allowing the maintenance technician to actuate the manually actuated pump element 12, for example, using a cordless screwdriver with a corresponding socket. Of course, other actuation methods using other external devices are also conceivable, for example, via a connectable foot or hand lever or even via an external motor.

[0042] Furthermore, the manually operable pump element 12 has a locking element 28. The locking element 28 is movable between a release position and a locking position. In the release position of the locking element 28, the drive shaft 19 is rotatable and the manually operable pump element 12 can be actuated. In the locking position, the locking element 28 blocks rotation of the drive shaft 19 so that the operating pressure currently applied to port 13 cannot be changed. In the illustrated embodiment, the locking element 28 is designed as a locking pin that is movable within the intermediate plate 25 such that rotation of the drive shaft is blocked in the locking position. Other designs are of course also conceivable, for example, using a switching disc that can be switched via a switching lever and that blocks rotation in one direction at a time depending on the position of the switching lever.

[0043] As in Fig. 3, the pressure chamber 11 is also connected to the brake caliper 2 via a leakage line 29. In this exemplary embodiment, the tank chamber i30 is designed as an additional tank 30. The leakage line 29 and the additional tank 30 are connected to the pressure chamber 11 via a check valve 32. This ensures that sufficient hydraulic fluid is stored in the hydraulic system 10 to generate the operating pressure required for actuating the brake caliper 2 or to provide the required amount. The volume of the additional tank 30 and the leakage line 29 preferably corresponds at least to the maximum volume of the pressure chamber 11.

[0044] In Fig. Figure 4 shows an alternative exemplary structural design of a hydraulic system 10 according to the invention according to the first embodiment. In this exemplary embodiment, the tank chamber 30 is formed at least partially within the housing 18. As shown, the pressure chamber 11 is delimited by the second piston part 22, so that the tank chamber 30 is also formed by the housing 18 and the second piston part 22 and is separated from the pressure chamber 11 by the second piston part 22. The second piston part 22 has the pressure relief valve 15 and the check valve 32.

[0045] A through-bore 33 is formed in the first piston part 21, which communicates with an additional connection 34 on the housing. An additional tank (not shown) can be provided at the additional connection 34 to provide sufficient volume of the tank chamber 30 if necessary.

[0046] By moving the piston element 20 via the drive shaft 19, the operating pressure is generated at port 13. Any excess pressure can be relieved directly via the pressure relief valve 15. Hydraulic fluid can be resuspended via the check valve 32.

[0047] The Fig. The embodiment shown in Figure 4 can be provided in cartridge design so that it can be installed quickly and easily.

[0048] Fig. Figure 5 shows a hydraulic circuit diagram of a hydraulic system 50 according to the invention according to a second embodiment. The hydraulic system 50 has a pressure chamber 11, a tank chamber 30, a manually operable pump device 12, and a connection 13. During maintenance of the wind turbine 100, the maintenance technician can generate the necessary operating pressure of the rotor brake 1 via the manually operable pump device 12. For this purpose, the brake caliper 2 is connected via a line 3 to the connection 13 of the hydraulic system 100, as shown in Fig. 2 shown connected.

[0049] Furthermore, the hydraulic system 10 has a first bypass line 14 with a first closing valve 15 designed as a pressure relief valve. The first bypass line 14 connects the connection 13 directly to the tank chamber 30, bypassing the manually operated pump element 12. The pressure relief valve 15 protects the hydraulic system 10 in the event of a pressure overshoot.

[0050] In this embodiment, the manually operable pump element 12 is designed as a reversible gear pump with a drive shaft 51. The coupling section 27 is arranged at the axial end of the drive shaft 51 of the gear pump 12, so that a maintenance technician can connect a suitable external device, for example, a cordless screwdriver, to operate the gear pump 12 via a rotation of the drive shaft 51, as already described above for the first embodiment.

[0051] A manually releasable check valve 52 is arranged between the gear pump 12 and the connection 13. The check valve 52 opens in the direction of flow to the connection 13 and prevents the pressure applied to the brake caliper 2 from being gradually released via the leaky gear pump 12. To retract the brake caliper 2, the manually releasable check valve 52 is released by the maintenance technician.

[0052] For this purpose, the hydraulic system 50 has a manually operable lever mechanism 53. In the Fig. In the embodiment shown in Figure 5, the lever mechanism 53 is designed in the form of a button or a lever, which the maintenance technician must manually operate to unlock the check valve 52. This is also advantageous from a safety perspective, as it prevents accidental retraction of the brake caliper 2, for example, if the cordless screwdriver used as an external device is mistakenly set in the wrong direction of rotation.

[0053] An alternative embodiment of the lever mechanism 53 is shown in Fig. 6. The lever mechanism 53 is connected to the drive shaft 51 of the gear pump 12 and is actuated by an axial movement of the drive shaft 51. The maintenance technician can actuate the drive shaft 51, for example, by exerting a corresponding force on the external device connected to the coupling section 27. It is also conceivable, of course, for the drive shaft 51 to have an axially movable sleeve or the like, which is connected to the lever mechanism 53 and is axially movable relative to a base body of the drive shaft 51.

[0054] This, with reference to the Fig. 5 and Fig. 6 described hydraulic system 50 can be analogous to that in Fig. 2 shown hydraulic system 10 with a rotor brake 1 for a wind turbine 100.

[0055] Finally, it should be noted that the numerals used here, such as “first” or “second,” do not specify a specific order, but merely serve to distinguish concepts. LIST OF REFERENCE SYMBOLS 1 rotor brake 2 brake calibers 3 Line 10 Hydraulic system 11 Printing room 12 manually operated pump element / gear pump 13 Connection 14 first bypass line 15 first closing valve / pressure relief valve 16 second bypass line 17 second closing valve / shut-off valve 18 housings 19 Drive shaft 20 piston element 21 first piston part 22 second piston part 23 Preload element 24 warehouses 25 intermediate plate 26 threaded connection 27 Coupling section 28 Securing element 29 Leakage line 30 Tank room / additional tank 31 rings 32 Check valve 33 through hole 34 Additional connection 50 Hydraulic system 51 Drive shaft 52 manually operated check valve 53 Lever mechanism 100 wind turbines 102 Tower 104 gondolas 106 Rotor 108 rotor blades QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2007 002 137 A1

[0003] DE 10 2017 102 375 B3

[0003]

Claims

[1] Hydraulic system (10, 50) for a rotor brake (1) of a wind turbine (100), wherein the hydraulic system (10, 50) has a manually operable pump device (12) and a connection (13) for connection to the rotor brake (1), wherein the manually operable pump device (12) is connected to and to the connection (13), characterized by that the manually operable pump device (12) has a coupling section (27) for actuation, wherein the coupling section (27) is connectable to an external device. [2] Hydraulic system (10, 50) according to one of the preceding claims, characterized by that the hydraulic system (10, 50) is designed in cartridge construction. [3] Hydraulic system (10, 50) according to claim 1 or 2, characterized by that the hydraulic system (10, 50) further comprises a tank chamber (30), wherein the tank chamber (30) is connected to the pump element (12). [4] Hydraulic system (10, 50) according to claim 3, characterized byin that the hydraulic system (10, 50) has a first bypass line (14), wherein the first bypass line (14) connects the connection (13) to the tank chamber (30) bypassing the manually operable pump element (12), and wherein a first closing valve (15) is arranged in the first bypass line (14). [5] Hydraulic system (10, 50) according to claim 4, characterized by that the first closing valve (15) is a pressure relief valve or a shut-off valve. [6] Hydraulic system (10) according to one of the preceding claims 3 to 5, characterized by in that the hydraulic system (10) has a second bypass line (16), wherein the second bypass line (16) connects the connection (13) to the tank chamber (30) bypassing the manually operable pump element (12), and wherein a second closing valve (17) is arranged in the second bypass line (16). [7] Hydraulic system (10) according to claim 6, characterized bythat the second closing valve (17) differs from the first closing valve (15) and wherein the second closing valve (15) is a pressure relief valve or a shut-off valve. [8] Hydraulic system (10) according to one of the preceding claims, characterized by that the hydraulic system (10) is hydraulically preloaded, preferably via a spring preload integrated in the manually operable pump device (12) or an integrated hydraulic accumulator. [9] Hydraulic system (10) according to one of the preceding claims, characterized by that the external device connectable to the coupling section (27) is a tool or an external motor. [10] Hydraulic system (10) according to one of the preceding claims. characterized byin that the manually operable pump device (12) has a pressure chamber (11), a housing (18), a drive shaft (19) and a piston element (20), wherein the pressure chamber (11) is formed within the housing (18), wherein the piston element (20) is movably arranged in the pressure chamber (11), wherein the drive shaft (19) is rotatably mounted relative to the housing (18) and is connected to the piston element (20), wherein a rotation of the drive shaft (19) moves the piston element (20) linearly in the pressure chamber (11). [11] Hydraulic system (10) according to claim 10, characterized by that the piston element (20) is guided within the housing (18) in such a way that rotation of the piston element (20) relative to the housing (18) is prevented, or wherein the drive shaft (19) is axially movable relative to the housing (18) and moves together with the piston element (20). [12] Hydraulic system (10) according to claim 10 or 11, characterized byin that the piston element (20) has a first piston part (21), a second piston part (22) and a prestressing element (23), wherein the first piston part (21) is connected to the drive shaft (19) and wherein the second piston part (22) is connected to the first piston part (21) via the prestressing element (23). [13] Hydraulic system (10) according to one of the preceding claims 10 to 12, characterized by in that the manually operable pump device (12) has a securing element (28) which is movable between a release position and a securing position, wherein the securing element (28) fixes the drive shaft (19) in the securing position in a rotationally fixed manner relative to the housing (18) and wherein the drive shaft (19) is rotatable relative to the housing (18) in the release position of the securing element. [14] Hydraulic system (50) according to one of the preceding claims 1 to 5, characterized bythat the manually operable pump device (12) is a gear pump with a drive shaft (51), wherein the coupling section (27) is arranged on the drive shaft (51). [15] Hydraulic system (50) according to claim 14, characterized by that a manually unlockable check valve (52) is arranged between the gear pump (12) and the connection (13). [16] Hydraulic system (50) according to claim 15, characterized by that the hydraulic system (50) has a manually operable lever mechanism (53) for unlocking the check valve (52). [17] Hydraulic system (50) according to claim 16, characterized by that the manually operable lever mechanism (53) is connected to the drive shaft (51) of the gear pump, wherein an axial movement of at least part of the drive shaft (51) actuates the lever mechanism (53) and unlocks the check valve (52). [18] Hydraulic system (10, 50) according to one of the preceding claims, characterized bythat the manually operable pump device (12) is a reversible manually operable pump device (12). [19] Rotor brake (1) for a wind turbine (100), wherein the rotor brake (1) comprises at least one brake caliber (2) and a hydraulic system (10, 50) according to one of the preceding claims, wherein the brake caliber (2) is hydraulically connected to the connection (13) of the hydraulic system (10). [20] Wind turbine (100) with a rotor brake (1) according to claim 19.

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