CRANE AND METHOD FOR WEATHERVANING SUCH A CRANE

Abstract

The present invention relates to a method for weathervaning of a crane which has a boom which can rotate about a vertical axis, a slewing gear motor and a slewing gear service brake for securing the boom in a rotational position with a securing torque in the crane mode, wherein in the case of a crane which has been out-of-operation, the boom is braked against rotation with an out-of-operation mode braking torque which is less than said securing torque in the crane mode. In this respect, the invention also relates to such a crane itself, in particular in the form of a revolving tower crane. In accordance with the invention, the out-of-operation mode braking torque is kept at least approximately constant over the range of the speed of rotation and over the range of the angle of rotation of the boom.

Claims

1. A method for weathervaning a crane having a boom configured to rotate about a vertical axis, a slewing gear motor, and a slewing gear brake for securing the boom in a rotational position with a securing torque in the crane mode, the method comprising: braking the boom against rotation with an out-of-operation mode braking torque which is less than the securing torque in the crane mode when the crane has been set out of operation, and keeping the out-of-operation mode braking torque constant over the range of the speed of rotation and over the range of the angle of rotation of the boom.

2. The method of claim 1, further comprising applying the out-of-operation mode braking torque by a torque limiting coupling, wherein the torque limiting coupling comprises a hysteresis clutch or a hysteresis brake, and wherein the toque limiting couple is between the slewing gear brake and the slewing gear drive or between the slewing gear drive and an output gear.

3. A revolving tower crane comprising: a boom configured to rotate about a vertical axis; a slewing gear; a drive train of the slewing gear comprising: a slewing gear motor for rotating the boom about the vertical axis; a slewing gear brake for braking the rotation of the boom; and a torque limiting coupling comprises a hysteresis clutch between the slewing gear motor and the slewing gear brake or between the slewing gear motor and an output gear engaged with a slewing ring connected to the boom in a manner secured against rotation.

4. The crane of claim 3, wherein the hysteresis clutch is configured with a gap of adjustable size.

5. The crane of claim 4, the hysteresis clutch having a conical gap, wherein at least one of the clutch halves of the hysteresis clutch is configured to be axially adjustable so that the conical gap is adjusted in its radial gap dimension and/or in its axial length.

6. The crane of claim 4, wherein the hysteresis clutch has a cylindrical gap and clutch halves, wherein at least one of the clutch halves is configured to be axially adjustable so that the cylindrical gap is adjusted in its axial length.

7. The crane according to claim 3, further comprising an out-of-operation control apparatus for varying the torque limiting coupling between an out-of-operation position in which the torque limiting coupling provides a slip torque which is smaller than the service securing torque provided by the slewing gear brake, and an in-operation position in which the torque limiting coupling provides a slip torque which is at least as large as the securing torque of the slewing gear brake.

8. The crane of claim 7, wherein the hysteresis clutch has clutch halves, and wherein the out-of-operation control apparatus is configured to axially adjust one of the clutch halves of the torque limiting coupling.

9. The crane of claim 3, wherein the torque limiting coupling is integrated into a slewing gear transmission and is contained within a transmission housing of the slewing gear transmission.

10. The crane of claim 3, wherein the slewing gear brake is adjustably configured in its braking torque so that braking torques of different magnitudes can be provided, further comprising an out-of-operation control apparatus for adjusting the slewing gear brake to an out-of-operation mode braking torque which is smaller than a securing torque provided to a crane mode.

11. The crane of claim 10, wherein the slewing gear brake is configured to be spring-actuated and has a spring device adjustable in its spring force for applying braking forces of different magnitudes.

12. The crane of claim 11, wherein the out-of-operation control apparatus is configured to adjust a spring preload of the spring device so that the spring device provides a lower spring force in the case of a crane that has been set out of operation compared to when the crane is in a default crane mode.

13. The crane of claim 10, wherein the out-of-operation mode braking torque is between 5% to 50% or between 5% and 25% of the securing torque provided during the crane mode.

14. The crane of claim 10, wherein the slewing gear brake comprises synthetic friction linings.

15. The crane of claim 3, wherein the slewing gear brake comprises synthetic friction linings.

16. The method of claim 1, wherein the out-of-operation mode braking torque is between 5% to 50% or between 5% and 25% of the securing torque provided during the crane mode.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The invention will be explained in more detail in the following with respect to preferred embodiments and to associated drawings. The drawings show:

[0033] FIG. 1: a perspective, portion-wise representation of a revolving tower crane in accordance with an advantageous embodiment of the invention which is configured as a top-slewer and which has a slewing gear for rotating the boom relative to the tower;

[0034] FIG. 2: a schematic representation of the slewing gear drive of the crane of FIG. 1, wherein in accordance with an advantageous embodiment of the invention an adjustable torque limiting coupling in the form of a hysteresis clutch is integrated into the slewing gear between the drive motor and the output gear, and

[0035] FIG. 3: a schematic representation of the slewing gear drive of the crane of FIG. 1 in accordance with an alternative embodiment of the invention, in which only one slewing gear brake is provided, which is in the form of an adjustable spring-actuated friction brake.

DETAILED DESCRIPTION

[0036] As FIG. 1 shows, the crane forming the object can be a revolving tower crane 1 configured as a so-called top-slewer whose tower 2 supports a boom 3 and a counter-boom 4 which extend substantially horizontally and which are rotatable about the upright tower axis 5 relative to the tower 2. Instead of the crane configuration shown in FIG. 1, the revolving tower crane 1 can, however, also be configured as a bottom-slewer and/or can comprise a luffable, pointed boom and/or can be guyed via a guying with respect to the tower foot or the superstructure.

[0037] To be able to rotate the boom 3, a slowing gear 6 is provided which is provided in the embodiment shown at the upper end of the tower 2 between the boom 3 and the tower 2 and which can comprise a sprocket with which a drive wheel driven by a drive motor 7 can mesh.

[0038] An advantageous embodiment of the drive device of the slewing gear 6 can comprise an electrical drive motor 7 which can drive a drive shaft via a slewing gear transmission. Said slewing gear transmission can, for example, be a planetary gear to step the speed of the drive motor 7 up/down into a speed of the output shaft in a suitable manner.

[0039] To be able to brake rotary movements of the boom 3 in crane operation and/or to be able to maintain a rotary position of the boom 3 which has been moved to, the slewing gear 6 comprises a slewing gear service brake which can, for example, be arranged on the input side of the slewing gear transmission. The service brake can comprise, for example, in a manner known per se a frictional disk brake device or a multi-disk brake device which is preloaded into the braking position by a preloading device and which can be lifted by an electric adjustment actuator in the form of an electric magnet, for example, to release the brake. Alternatively or additionally to such a mechanical service brake, an electric-motor service brake can also be provided, for example in the form of a brake chopper having connectable braking resistances which can be integrated into or connectable/can be connected with the inverter controlling the electric motor 2.

[0040] As FIG. 2 shows, a torque limiting coupling 10 can be integrated in the slewing gear transmission 9, i.e. between the drive motor 7 and the drive gear 11, which is advantageously configured as a hysteresis clutch and is adjustable with regard to its slip torque.

[0041] Preferably, the hysteresis clutch forming the slip clutch 10 may be of cylindrical construction and/or have an internal permanent-magnetic rotor and an external hollow cylindrical hysteresis ring. Such an arrangement allows for an easy cooling of the hysteresis ring, which may be subject to considerable heating during operation.

[0042] The air gap of the hysteresis clutch may be free of oil or, advantageously, filled with oil, for example when the torque limiting coupling 20 runs in the oil bath of the slewing gear transmission. In this respect, the heat generated is dissipated via the oil bath of the transmission housing, although a separate oil circuit can also be provided.

[0043] For the purpose of possible adjustment of the slip torque of the torque limiting coupling 20, said hysteresis clutch may advantageously have an air gap which is configured to be adjustable. In the case of a cylindrical air gap, axial adjustment of at least one clutch half can be used to shorten it axially while maintaining the same radial air gap width in order to adjust the slipping torque as required.

[0044] Advantageously, however, said air gap between the clutch halves can also be conically configured in order to adjust the air gap both in its radial as well as in its axial width or length by means of an axial adjustment of at least one clutch half. By adjusting the size of the air gap, the slip torque and/or the shape or steepness of the torque/slip characteristic can be adjusted and set.

[0045] An out-of-operation control apparatus 12, shown only schematically, can perform said axial adjustment of the hysteresis adjustment to set the slip torque to the required low value well below the securing torque required in crane mode in the case of a crane which has been out of operation.

[0046] For regular crane mode, the two halves of the clutch are then adjusted axially in relation to each other again in such a way that a relatively high slip torque is provided, which can also be significantly above the securing torque of the service brake.

[0047] As FIG. 3 shows, however, the slewing gear brake 8 itself can also be used to provide a constant braking torque when the crane is shut down so that it is not pulled loose when the rotary movement is initiated. In particular, the slewing gear brake 8 can be configured to be adjustable with regard to the torque it provides.

[0048] The slewing gear brake 8 can in particular be a wheel-actuated brake that can be set to a defined braking torque, for example by the spring device 13 being configured to be adjustable for preloading the friction elements against each other.

[0049] For example, said out-of-operation control apparatus 12 can deactivate a part of the spring elements when the crane is stopped, so that when the crane is stopped, only a part of the spring elements and therefore a part of the spring preload is active. In the regular crane mode, however, all spring elements can be activated, wherein the spring device can be released or the spring preload can be overcome by a pressure medium cylinder when the slewing gear is actuated. If the air cylinder is then deactivated again, all spring elements engage and press the friction elements of the brake against each other to provide the full holding or braking force.

[0050] Advantageously, the service brake has been equipped with synthetic friction linings.