Crane with active backfall support

Abstract

The invention relates to a crane (10) comprising a support structure (11), a boom (16) pivotably connected to the support structure (11) about a horizontal luffing axis, a guying frame (18) connected to the support structure (11), via which the boom (16) is guyed by means of a length-adjustable guying (19), and a fall-back safety device (20) arranged on the guying frame (18), which is designed to block or brake a tilting of the boom (16) towards the guying frame (18) in a critical state of the crane (10), in particular in the event of a load break, wherein the fall-back safety device (20) comprises at least one support strut (22) with which the boom (16) comes into contact when luffing up at a defined boom angle. According to the invention, the support strut (22) is designed as a rigid element,which follows the boom (16) above the defined boom angle and can be actively retracted and / or extended relative to the guy frame (18) by means of a cable winch system (30) of the fall-back safety device (20).

Description

[0001] The present invention relates to a crane according to the preamble of claim 1 and a fall-back safety device for such a crane.

[0002] Cranes of this type are often designed as heavy-duty ship cranes or offshore heavy-duty cranes and have a boom that can be luffed around a horizontal axis and is guyed via a guy frame using adjustable-length guy wires. The boom is luffed up and down by operating the guy wires via a retracting mechanism.

[0003] With such cranes, the rolling behavior of the ship, which can occur, for example, in the event of a load break, but also due to load loss or shifting on deck, can cause the boom to swing back toward the guy frame, which can lead to damage to the boom and the guy frame. For this reason, it is known from the state of the art to equip such cranes with hydraulic anti-return cylinders that contact the boom at a certain maximum boom angle and, in the event of a load break, block or slow down any swinging back.

[0004] A disadvantage of these systems is that the hydraulic cylinders used have a large differential volume and therefore require a large volume of oil, which must be pumped in a short time. The cylinders must be matched to the overall system with regard to maximum length and holding force.

[0005] Furthermore, due to their design, hydraulic cylinders are prone to buckling, requiring the installation of relatively large and heavy components. For this reason, the maximum length of the cylinders is usually limited, meaning that the entire danger zone cannot often be covered (i.e., the fall-back protection only engages at relatively large boom angles).

[0006] Furthermore, when the boom is supported, the oil is compressed, resulting in a reduction in the distance between the boom and the guy frame, as the cylinders rest on a compressible column of oil. This inevitably leads to slack in the guy wires or the hoisting gear. Depending on the ship's roll motion, the boom may enter a free-fall phase, which can lead to overloading or failure of the boom structure, the hoisting gear, and / or other components in the load path.

[0007] The present invention is therefore based on the object of specifying a generic crane with a fall-back safety device in which the aforementioned disadvantages do not occur and which reduces the extent of damage in the event of a load break to a minimum.

[0008] According to the invention, this object is achieved by a crane having the features of claim 1 and by a fall-back safety device having the features of claim 15. Advantageous embodiments of the invention emerge from the subclaims and the following description.

[0009] Accordingly, a crane is proposed which comprises a support structure, a boom pivotably connected to the support structure about a horizontal luffing axis, a guying frame connected to the support structure, and a fall-back safety device arranged on the guying frame. The boom is guyed via the guying frame (also referred to as an A-frame) by means of a length-adjustable guying system, in particular a guying cable. As described above, the boom can be luffed up and down, in particular by changing the length of the guying system via a retractable mechanism. The boom can be a lattice boom. Alternatively, a box boom is also conceivable.

[0010] The anti-fallback device is designed to block or slow down the boom from tilting toward the guy frame in a critical crane condition, particularly in the event of a load break. This prevents damage to the guy frame and the boom, as the latter is blocked or slowed down by the anti-fallback device before it reaches the guy frame. For this purpose, the anti-fallback device comprises at least one support leg, with which the luffing boom comes into contact when the defined boom angle is reached. Below the defined boom angle, the boom is not in contact with the support leg (for simplicity, we will refer to "the support leg" below - however, at least one support leg is always meant).

[0011] According to the invention, the support leg is not designed as a piston-cylinder unit, but as a rigid element, for example a steel girder. Furthermore, the support leg is not immovably attached to the guy frame, but actively or passively follows the boom above the defined boom angle. To this end, the support leg retracts above the defined boom angle when the boom luffs up, ensuring that it is always in contact with the boom. Conversely, the support leg extends above the defined boom angle when the boom luffs down, maintaining contact with the boom. For this purpose, the fallback safety device comprises a cable winch system by means of which the support leg can be actively retracted and / or actively extended relative to the guy frame.

[0012] This tracking ensures that above the defined boom angle, if a critical condition occurs, such as a load break, the support leg and thus the boom can be immediately blocked or braked. The danger zone covered by the fall protection device is therefore determined by the defined boom angle, which should therefore be as small as possible (in order to achieve the largest possible protected angle range). This can be achieved according to the invention by designing the support leg as a rigid element, allowing a greater length and thus a larger covered danger zone. This makes it possible to achieve defined boom angles of 60°, but also smaller angles of, for example, 50° or less (i.e. in the latter case, the fall protection device according to the invention would already be active at a boom angle to the horizontal of 50° or less).

[0013] During normal operation, the stabilizing support moves freely, i.e., without exerting significant force on the boom. Therefore, during normal operation, the boom can be freely luffed up and down, particularly in the danger zone, i.e., above the defined boom angle. Only in critical conditions is the retraction of the stabilizing support, and thus further luffing of the boom above the defined boom angle, blocked or braked.

[0014] Compared to the solution based on hydraulic cylinders, the inventive solution, in which the support leg is extended and / or retracted by a cable winch, offers several advantages. For example, the at least one cable winch of the cable winch system requires significantly less oil than conventional hydraulic cylinders (in the case of a hydraulically operated winch) or no oil at all (in the case of an electrically operated winch).

[0015] In addition, a rigid safety structure allows for the implementation of longer support strut lengths, allowing contact between the boom and support strut to occur even at a smaller defined boom angle. This allows the boom to be blocked or braked earlier, thus covering a larger danger area.

[0016] Furthermore, with a winch-based system, the same basic fall-back safety device system can be used with different reeving arrangements for different cases or different cranes. Changing the reeving arrangement is a relatively minor intervention in the system. The braking force could be varied, for example, by adding or removing brake units (modular system).

[0017] Furthermore, a rigid support holds the boom in a fixed position relative to the guy frame, thus preventing the formation of slack rope in the guy system.

[0018] Finally, winches are significantly less susceptible to corrosion than cylinders, especially the piston rod. During extended downtimes, hydraulic cylinders can experience corrosion on the piston rod, which can lead to leaks and seal damage.

[0019] In this case, the information on the boom angle (e.g. large / small boom angle) refers in particular to the angle between the boom longitudinal axis and the horizontal.

[0020] The defined boom angle can be in the range of 50-70°, preferably in the range of 50-60°, although defined boom angles of less than 50° or, depending on the crane design, of more than 70° are also possible.

[0021] Theoretically, the fall-back safety device according to the invention could achieve a defined boom angle of less than 40°, less than 30°, less than 20°, less than 10°, or even, in extreme cases, down to 0°. However, such a large protected danger zone would be achieved at the cost of increased weight of the fall-back safety device. For this purpose, the support can, for example, be pivotably attached to the guy frame and / or have a shape curved downwards or toward the boom.

[0022] The fall-back safety device according to the invention is preferably designed so that the boom can be tilted up to an angle of 90° (i.e. the secured danger area extends up to 90°).

[0023] In one possible embodiment, the support leg can be actively retracted and extended using the cable winch system. During luffing, the support leg actively extends and follows the boom synchronously until the boom falls below the defined boom angle. Conversely, the support leg is actively retracted by the cable winch system above the defined boom angle, synchronously with the luffing boom.

[0024] For this purpose, the cable winch system preferably comprises a cable winch designed as a traversing winch, which can be operated in both directions. A cable is mounted on the cable winch, which is attached to the support strut at both ends rather than at one end to the cable winch. By rotating the cable winch in one direction or the other, the support strut can be retracted or extended. By using a single winch to extend and retract the support strut, fewer components are required. The cable is preferably guided via several pulleys to different ends of the support strut and secured there. The cable winch system can also comprise cable tensioners to prevent slack in the cable. These can each comprise one or more additional pulleys.

[0025] Alternatively, the support leg can be extended and retracted using two separate "normal" cable winches, with one of the cable winches pulling the support leg in the desired direction, while the other cable winch unwinds the other cable so that it follows the movement of the support leg.

[0026] In another possible embodiment, the support leg can be actively extended via the cable winch system and only passively retracted. Extension can be achieved using a standard cable winch. Passive retraction is achieved, in particular, by the boom luffing up using the guying or retracting gear, which exerts a corresponding force on the support leg. For this purpose, the cable winch can be released for retraction so that it can rotate freely, mediated by the luffing boom. Alternatively, the cable winch could also be operated with a defined counterpressure, which does not damage the boom, prevents slack in the cable, and ensures permanent contact with the boom.

[0027] In another possible embodiment, a catch device is arranged on the boom, with which the support comes into contact when the defined boom angle is reached. This creates a defined contact area between the support and the boom. The catch device preferably has a funnel-shaped opening into which an end of the support facing away from the guy frame moves when contact is made with the catch device. This ensures that the support always moves correctly into the catch device. The catch device can be arranged on the side of the boom facing the guy frame.

[0028] The fall arrester can be attached to the boom in an articulated manner, for example, to allow the support to track vertically or to compensate for relative vertical movement. Alternatively, the fall arrester can be permanently attached to the boom, for example, when using a curved support.

[0029] In another possible embodiment, the support strut is pivotally mounted on the guy frame in order to compensate for a vertical movement of a contact area of ​​the boom that is contacted by the support strut (this can be the aforementioned fall arrest device) when tracking a pivoting movement of the boom above the defined boom angle. When pivoting the boom, the contact area moves not only horizontally relative to the attachment point of the support strut, but also vertically. This must be compensated for when tracking the support strut. The support strut can, in particular, have a straight or linear shape.

[0030] In order to compensate for the vertical movement of the contact area during tracking, the support strut can be actively pivoted around its mounting on the guy frame by means of an actuator, for example by means of a hydraulic cylinder which is retracted or extended in a controlled manner.

[0031] Alternatively, according to a further possible embodiment, the support leg can have a curved shape and be designed such that, when tracking a pivoting movement of the boom above the defined boom angle, a vertical movement of a contact area of ​​the boom which is contacted by the support leg (this can be the aforementioned arresting device) corresponds to the vertical movement of an end section of the support leg contacting the contact area. In other words, the support leg can be curved or bent such that, when the support leg is extended and retracted, its end section describes a precise arc such that it follows the contact area of ​​the boom during luffing and swaying. As a result, the support leg does not have to be specifically tracked in the vertical direction, but can, for example, be mounted non-pivotably on the guy frame. The support leg is, in particular, curved downwards.

[0032] In another possible embodiment, the fall-back protection device comprises a pressure accumulator, which is "charged" when the support leg is retracted and discharged again when the support leg is extended, thereby supporting the cable winch system that extends the support leg. The pressure accumulator can be a hydraulic accumulator or, preferably, a gas pressure accumulator.

[0033] In a further possible embodiment, the fall-back safety device comprises a braking device which, when activated, actively or passively brakes the retraction of the support leg. Preferably, the support leg is braked to a standstill. The braking device is preferably activated automatically by a control device (e.g., the crane control system) upon detection of a critical condition (e.g., a load break), but can also be activated as standard whenever the boom is not moving (i.e., the braking device is activated when the boom stops).

[0034] The braking device can comprise an active force-locking braking system that is actuated hydraulically, electrically, or pneumatically. Alternatively or additionally, the braking device can comprise an active form-locking braking system that is actuated hydraulically, electrically, or pneumatically. It is also conceivable for the braking device to comprise a passive braking system that, after activation, brakes without any further force being applied and, for example, varies the braking force depending on the load (e.g., by means of a self-locking wedge).

[0035] In a further possible embodiment, the crane comprises a detection device with a sensor system for detecting a critical condition of the crane, in particular a load break. The sensor system can comprise at least one acceleration sensor, which can be arranged, for example, on the boom, on the guy frame, on a hoist rope or load-handling device, or at any other location on the support structure. It is also conceivable for the acceleration sensor to be part of the fall-back safety device. Alternatively or in addition to the aforementioned acceleration sensor, other sensors can be present, for example at least one inertial measuring unit (IMU), at least one proximity sensor, at least one mechanical limit switch, and / or at least one pressure sensor. These sensors can be arranged at different locations to monitor the crane and detect critical conditions.

[0036] The crane preferably further comprises a control unit that receives data from the detection device or the sensor system and is configured to detect a critical condition based on the received data and, in response, to actuate a locking device or a braking device of the fall-back protection device so that the boom is braked or blocked above the defined boom angle. The control unit can be the crane control system or a separate control unit.

[0037] As an alternative to a selective braking solution, which requires detection of a critical condition, the brake can be activated whenever the boom is not luffing. In this case, sensors for detecting a critical condition are not required.

[0038] In another possible embodiment, the fall-back safety device comprises at least one actuating unit with a bracket attached to the guy frame, in which the safety support is displaceably mounted, wherein the aforementioned cable winch system is part of the actuating unit. The actuating unit mounts the safety support, in particular, on the guy frame. In the case of a linear or straight safety support, which must be vertically adjusted when the boom is pivoted, the actuating unit can comprise an actuator that actively pivots the safety support or the bracket when the boom is luffing.

[0039] In a further possible embodiment, the actuating unit comprises the aforementioned braking device. The braking device can be integrated into the holder or be part of the holder. The braking device can, for example, comprise one or more braking elements that brake the support strut force-fittingly, form-fittingly, or passively, as described above. Alternatively, the braking device can be integrated into the cable winch system. For example, the support strut can be braked by braking the corresponding cable winch. The braking device can be an active braking system with a single or multiple reeving cable winch.

[0040] In another possible embodiment, the support bracket has a curved shape, as described above, and the bracket has a curved shape to slidably accommodate the curved support bracket. In this case, the bracket can be fixedly attached to the guy frame.

[0041] In another possible embodiment, the fall-back safety device comprises at least two support legs, which can preferably be retracted and / or extended via separate cable winch systems. Exactly two support legs can be provided, which can preferably be mounted laterally or in the lateral areas of the guy frame. Alternatively, more than two support legs can be provided, in particular a multiple of two support legs. These can, for example, be arranged one above the other on the guy frame and ensure even more effective braking of the boom, especially in cranes with very large and heavy booms.

[0042] In another possible embodiment, the support structure comprises a rotating platform mounted on a substructure for rotation about a vertical axis of rotation, on which the boom, the guy frame, and the fall-back safety device are arranged. The crane according to the invention is preferably a ship crane, in particular an offshore heavy-duty crane or a heavy-duty ship crane, wherein the substructure is connected to a ship's hull.

[0043] The present invention further relates to a fall-back safety device for a crane according to the invention. This obviously results in the same properties and advantages as for the crane according to the invention. All embodiments and design options of the fall-back safety device described with reference to the crane therefore also apply to the fall-back safety device according to the invention, in any combination.

[0044] Further features, details, and advantages of the invention will become apparent from the exemplary embodiments explained below with reference to the figures. They show: Fig. 1: a perspective view of a first embodiment of the crane according to the invention, wherein only the support structure with the boom is shown; Fig. 2-3: side views of the crane according to the embodiment of the Figure 1 with different boom positions; Fig. 4-5: a perspective view and a side view of a support support according to one embodiment; and Fig. 6-7: side views of the crane according to a second embodiment with different boom positions.

[0045] The Figure 1shows a perspective view of an embodiment of the crane 10 according to the invention in the form of an offshore heavy-duty crane, wherein the ship's hull is not shown. The crane 10 comprises a support structure 11 with a substructure 12 (connected to the ship's hull, not shown in this embodiment) and a rotating platform 14 mounted on the substructure 12 for rotation about a vertical axis of rotation.

[0046] The crane 10 comprises a boom 16, which is pivotally connected to the rotating platform 14 about a horizontal luffing axis. In the illustrated embodiment, the boom 16 is designed as a lattice boom with two boom legs converging to a boom head 13 to provide the boom 16 with the necessary stability for the considerable loads to be lifted. The boom head 13 has a plurality of deflection pulleys over which a (not shown) multiple-reeved hoist rope is guided and connected to a (also not shown) hook block.

[0047] A guying frame 18 is attached to the rotating platform 14, at the end of which are several pulleys, via which a guying cable 19 (= guying) is guided to the boom head 13. A retracting mechanism, which can comprise one or more guying cable winches 15 arranged at the rear of the rotating platform 14 (cf. Fig. 3 ) the boom 16 can be tilted up and down.

[0048] Due to the rolling behavior of the ship, in critical situations, particularly in the event of a load break, the boom 16 may swing back toward the guy frame 18, which can cause significant damage. To prevent this, the crane 10 includes a fall-back safety device 20, which is arranged on the guy frame 18 and configured to intercept and brake or stop the boom 16 from swinging back.

[0049] In the embodiment of the Figure 1 The fall-back safety device 20 comprises two support supports 22, which are designed as linear, parallel and rigid supports. Figures 4-5 show one of the support supports 22 in a perspective and a side view.

[0050] The rigid support struts 22 are each mounted on the guy frame 18 via an actuating unit 24 and have an end 23 pointing towards the boom 16, which, above a defined boom angle, is in contact with the side of the boom 16 facing the guy frame 18. The length of the support struts 22 therefore determines the defined boom angle. On the side of the boom 16 facing the guy frame 18, there are support devices 17 that form the contact areas for the ends 23 of the support struts 22 and, in the embodiment shown, have a funnel-shaped receptacle open towards the guy frame 18, which ensures proper retraction of the support struts 22 into the receptacles 17. In the embodiment shown, the defined boom angle is approximately 60° relative to the horizontal, but can also be larger or smaller depending on the crane type and design of the support struts 22.

[0051] The actuating units 24 each comprise a bracket 25 in which the respective guy support 22 is slidably mounted. Furthermore, the actuating units 24 each comprise a cable pull system 30 by means of which the respective guy support 22 can be retracted and extended. Retraction refers to a movement of the guy support 22 away from the boom 16, and extension refers to the opposite movement toward the boom 16.

[0052] In the Figures 4-5In the embodiment shown, the cable pull system 30 comprises a single cable winch 32, which is designed as a traversing winch and can thus move the support leg 22 in both directions. For this purpose, the two ends of the cable 34 wound on the traversing winch 32 are attached to the opposite ends of the support leg 22. The cable 34 is guided via a rear deflection pulley 36 of the cable pull system 30 to the rear end of the support leg 22 and via a front deflection pulley 37 of the cable pull system 30 to the front end of the support leg 22. In addition, the cable pull system 30 comprises a front cable tensioner 39 and a rear cable tensioner 38, each of which has a further deflection pulley and ensures that the cable 34 is always taut. Depending on the loads occurring and the design of the crane 10, the cable winches 32 can be reeved once or multiple times.

[0053] The support legs 22 can be actively retracted and actively extended via the cable winches 32. The cable winches 32 are controlled and / or regulated (for example, via the crane control system) in such a way that the support legs 22 track the movement of the boom 16 above the defined boom angle, so that the boom 16 can be freely rocked up and down above the defined boom angle during normal operation, but the support legs 22 are nevertheless always in contact with the fall arrest devices 17.

[0054] The tracking of the support supports 22 is in the Figures 2-3 These show the crane 10 in a side view in two different boom positions. Figure 2shows the boom 16 in a position in which the boom angle corresponds to the defined boom angle, from which the fall-back safety device 20 secures the movement of the boom 16, and in which the support supports 22 are maximally extended. Figure 3 shows the boom 16 in its maximum luffed position, in which the support legs 22 are maximally retracted.

[0055] If a critical condition of the crane 10 occurs, such as a load break in which the boom 16 suddenly swings back toward the guy frame 18, the retraction movement of the support legs 22 can be braked and finally stopped via braking devices 26 of the actuating units 24 in order to prevent a collision between the boom 16 and the guy frame 18. The braking devices 26 can comprise, for example, brake blocks, locking pawls, and / or a bolting as braking elements.

[0056] The braking devices 26 can comprise an active force-locking or form-locking braking system, which can be actuated hydraulically, electrically, or pneumatically. If a critical condition is detected, the braking devices 26 are activated, and force-locking or form-locking braking occurs. Alternatively, the support struts 22 can be actively braked via the single- or multi-reeved cable winches 32.

[0057] Alternatively, a passive braking system could be provided, which, for example, achieves a corresponding braking effect via self-locking wedges. Such a passive braking system must also be activated to slow or block the retraction movement of the support struts 22.

[0058] As in the Figures 2-3As can be seen, the arresting devices 17 move during a rocking movement of the boom 16 not only in the horizontal direction, but also in the vertical direction relative to the actuating units 24. Therefore, the arresting supports 22 in the embodiment shown, in which they are designed as linear supports, must also track the boom 16 in the vertical direction. For this purpose, the arresting devices 17 can have a correspondingly designed receiving area that allows tilting of the arresting supports 22 relative to the arresting devices 17. Furthermore, the actuating units 24 can be actively pivoted relative to the guy frame 18 via actuators, for example pivoted individually. Figure 1An embodiment is shown in which the actuating units 24 are mounted on a support 21 running parallel to the boom luffing axis, which support can be pivoted as a whole by means of actuators. The control and / or regulation of the actuators for pivoting the support supports 22 can be carried out via the same control unit (e.g., the crane control) as the control / regulation of the cable winches 32.

[0059] With an active braking system, detection of a critical condition (e.g., a loss of load or a rolling motion of the ship) is required. This can be achieved via a sensor system of a detection device of the crane 10, which can be based on various sensors, e.g., acceleration sensors, proximity sensors, mechanical limit switches, and / or pressure sensors. The sensor system is connected in particular to a control unit that controls or activates the cable winches 32 and / or the braking devices 26.

[0060] In the illustrated embodiment, the support struts 22 actively extend and retract to the defined boom angle. Alternatively, passive retraction can occur (particularly by the luffing boom 16), so that a traversing winch 32 is not required.

[0061] The Figures 6-7show an alternative embodiment of the crane 10 according to the invention, in which the support legs 22 are not straight or linear, but curved. These are curved or bent downwards. As a result, the ends 23 of the support legs 22 pointing towards the support devices 17 describe an arc when the boom 16 is adjusted, which arc follows the movement of the support devices 17. As a result, the support legs 22 do not need to be adjusted or pivoted in the vertical direction. The actuating units 24 can therefore be firmly connected to the guy frame 18, but must be designed in such a way (e.g. by means of a correspondingly curved holder 25) that the curved support legs 22 are slidably guided or mounted therein. List of reference symbols:

[0062] 10Crane 11Support structure 12Substructure 13Boom head 14Slewing platform 15Guy winch / retracting gear 16Boom 17Arrester 18Guying frame 19Guying 20Reversion safety device 21Beam 22Support strut 23End 24Actuating unit 25Bracket 26Braking device 30Cable winch system 32Cable winch 34Cable 36Deflection pulley 37Deflection pulley 38Cable tensioner 39Cable tensioner

Claims

1. Crane (10) comprising a support structure (11), a boom (16) pivotably connected to the support structure (11) about a horizontal luffing axis, a guying frame (18) connected to the support structure (11), via which the boom (16) is guyed by means of a length-adjustable guying (19), and a fall-back safety device (20) arranged on the guying frame (18), which is designed to block or brake a tilting of the boom (16) towards the guying frame (18) in a critical state of the crane (10), in particular in the event of a load break, wherein the fall-back safety device (20) comprises at least one support support (22) with which the boom (16) comes into contact when luffing up at a defined boom angle, characterized by thatthe support strut (22) is designed as a rigid element which follows the boom (16) above the defined boom angle and can be actively retracted and / or extended relative to the guy frame (18) by means of a cable winch system (30) of the fallback safety device (20).

2. Crane (10) according to claim 1, wherein the support leg (22) can be actively extended and retracted by means of the cable winch system (30), and wherein the cable winch system (30) preferably comprises a cable winch (32) designed as a traversing winch, on which a cable (34) is mounted, which cable is guided in particular via a plurality of deflection rollers (36) to different ends of the support leg (22) and is fastened there.

3. Crane (10) according to claim 1, wherein the support leg (22) is actively extendable via the cable winch system (30) and wherein the support leg (22) is passively retractable, in particular by the luffing boom (16).

4. Crane (10) according to one of the preceding claims, wherein a catch device (17) is arranged on the boom (16), with which the catch support (22) comes into contact when the defined boom angle is reached, wherein the catch device (17) preferably has a funnel-shaped opening area into which an end of the catch support (22) facing away from the guy frame (18) moves when the catch device (17) comes into contact.

5. Crane (10) according to one of the preceding claims, wherein the support bracket (22) is pivotally mounted on the guy frame (18) in order to compensate for a vertical movement of a contact area of ​​the boom (16) which is contacted by the support bracket (22) during a pivoting movement of the boom (16) above the defined boom angle, wherein the support bracket (22) preferably has a linear shape.

6. Crane (10) according to one of claims 1 to 4, wherein the support bracket (22) has a curved shape and is designed such that, during a pivoting movement of the boom (16) above the defined boom angle, a vertical movement of a contact region of the boom (16) which is contacted by the support bracket (22) corresponds to the vertical movement of an end section of the support bracket (22) contacting the contact region, wherein the support bracket (22) is preferably not pivotably mounted on the guy frame (18).

7. Crane (10) according to one of the preceding claims, wherein the fall-back safety device (20) comprises a pressure accumulator, in particular a gas pressure accumulator, which is charged when the support leg (22) is retracted and supports the cable winch system (30) when the support leg (22) is extended.

8. Crane (10) according to one of the preceding claims, wherein the fall-back safety device (20) comprises a braking device (26) which, when activated, actively or passively brakes a retraction of the support leg (22), wherein the activation preferably takes place automatically by a control device upon detection of a critical condition or always upon a stop of the boom (16), wherein the braking device (26) preferably comprises an active non-positive or positive braking system or a passive braking system and in particular one based on a self-locking wedge.

9. Crane (10) according to one of the preceding claims, further comprising a detection device with a sensor system for detecting a critical condition of the crane (10), in particular a load break, wherein the crane (10) preferably further comprises a control unit which receives data from the detection device and is configured to actuate a locking device or a braking device (26) of the fall-back safety device (20) when a critical condition is detected.

10. Crane (10) according to one of the preceding claims, wherein the fall-back safety device (20) comprises at least one actuating unit (24) with a holder (25) fastened to the guy frame (18), in which the support strut (22) is displaceably mounted, wherein the actuating unit (24) comprises the cable winch system (30).

11. Crane (10) according to the preceding claim and further developed by the features of claim 8, wherein the actuating unit (24) comprises the braking device (26), wherein the braking device (26) is preferably integrated into the holder (25) or into the cable winch system (30).

12. Crane (10) according to one of the two preceding claims and further developed by the features of claim 5, wherein the holder (25) has a curved shape in order to slidably receive the curved support (22).

13. Crane (10) according to one of the preceding claims, wherein the fall-back safety device (20) comprises at least two support supports (22), which can preferably be retracted and / or extended via separate cable winch systems (30).

14. Crane (10) according to one of the preceding claims, wherein the support structure (11) comprises a rotating platform (14) mounted on a substructure (12) for rotation about a vertical axis of rotation, on which platform the boom (16), the guy frame (18) and the fall-back safety device (20) are arranged, wherein the crane (10) is preferably a ship crane, particularly preferably an offshore heavy-duty crane and the substructure (12) is connected to a ship's hull.

15. Fall-back safety device (20) for a crane (10) according to one of the preceding claims.

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