Crane with active fallback support

Abstract

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

Description

The present invention relates to a crane according to the preamble of claim 1 and to a fall-back prevention device for such a crane.Cranes of this type are frequently designed as heavy-duty ship cranes or as offshore heavy-duty cranes and have a boom which can be swung about a horizontal axis and which is guyed via a guying block by means of a guying stranding of variable length. The swinging up and down of the boom is effected by actuating the guy stranding via a drawing-in unit.In such cranes, due to the rolling behavior of the ship, which can occur, for example, in the event of a load break but also in the event of load loss or displacements on the deck, the boom can swing back in the direction of the guying block, which can lead to damage to the boom and the guying block. For this reason, it is known from the prior art to equip such cranes with hydraulic fall-back prevention cylinders which contact the boom at a specific maximum boom angle and block or brake a swing-back in the event of a load stall.A disadvantage of these systems is the fact that the hydraulic cylinders used have a large differential volume and therefore require a large oil volume which has to be pumped in a short time. The cylinders are to be matched to the overall system with regard to the maximum length and holding force.In addition, hydraulic cylinders are susceptible to buckling due to their design, which is why comparatively large and heavy components have to be installed. For this reason, the maximum length of the cylinders is usually limited, so that the entire danger zone cannot often be covered (i.e. the intervention of the fall-back prevention device takes place only at comparatively large boom angles).Furthermore, when supporting the boom, the oil is compressed and consequently the distance from boom to guying frame is reduced, since the cylinders are supported on a compressible oil column. This inevitably leads to a lap rope formation in the guy stranding or in the drawing-in unit. Depending on the rolling movement of the ship, the boom can thereby enter a free fall phase, which can lead to overloading or failure of the boom structure, the drawing-in mechanism and / or further components located in the load path.The object of the present invention is therefore to specify a crane of the generic type having a fall-back prevention device in which the aforementioned disadvantages do not occur and which reduces the extent of damage to a minimum in the event of a load disconnection.According to the invention, this object is achieved by a crane having the features of claim 1 and by a fall-back prevention device having the features of claim 15. Advantageous embodiments of the invention are evident from the dependent claims and the following description.Accordingly, a crane is proposed which comprises a support structure, a boom connected to the support structure such that it can be pivoted about a horizontal luffing axis, a guying bracket connected to the support structure and a fall-back prevention device arranged on the guying bracket. The boom is guyed via the guying frame (also referred to as an A-frame) by means of a length-variable guying, in particular a guy stranding. As described at the beginning, the boom can be bent up and down, in particular by changing the length of the guying by means of a drawing-in unit. The boom can be a lattice mast boom. Alternatively, a box boom is also conceivable.The fall-back prevention device is configured to block or brake tilting of the boom in the direction of the guying block in a critical state of the crane, in particular in the event of a load disconnection. Damage to the guying block and the boom is thereby avoided, since the boom is still blocked or braked by the fall-back prevention device before reaching the guying block. For this purpose, the fall-back prevention device comprises at least one intercepting support with which the tilting boom comes into contact when the defined boom angle is reached. Below the defined boom angle, the boom is not in contact with the intercepting support (in the following, for the sake of simplicity, only "the intercepting support" is mentioned-but at least one intercepting support is always intended to be meant).According to the invention, the intercepting support is not designed, for example, as a piston-cylinder unit, but as a rigid element, for example as a steel support. The arresting support is furthermore not fixed immovably to the guying frame, but rather is actively or passively tracked to the boom above the defined boom angle. For this purpose, the intercepting support moves above the defined boom angle when the boom is pivoted open in such a way that it is always in contact with the boom. Conversely, the intercepting support extends above the defined boom angle upon tilting of the boom to remain in contact with the boom. For this purpose, the fall-back prevention device comprises a cable winch system, by means of which the intercepting support can be actively retracted relative to the guy support and / or can be actively extended.This follow-up ensures that above the defined boom angle, in the event of a critical state such as a load stall, the intercepting support and thus the boom can be blocked or braked directly. The danger area covered by the fall-back securing device is therefore defined by the defined boom angle, which should therefore be as small as possible (in order to achieve a secured angle range as large as possible). This can be achieved according to the invention in that the configuration of the intercepting support as a rigid element allows a greater length and thus a greater covered danger area. As a result, defined cantilever angles of 60° but also smaller angles of, for example, 50° or less can be reached (i.e. in the latter case the fall-back prevention device according to the invention would already be active starting from a cantilever angle to the horizontal of 50° or less).The follow-up of the intercepting support takes place in normal operation in particular freely, i.e. without significant exertion of force on the boom. During normal operation, this can therefore also be freely switched on and off, in particular, in the danger zone, i.e. above the defined boom angle. Only in the critical state is a retraction of the arresting support and thus a further tilting of the boom above the defined boom angle blocked or braked.Compared to the solution based on hydraulic cylinders, the solution according to the invention, in which the retraction and / or extension of the arresting support takes place by cable winch, offers several advantages. Thus, the at least one cable winch of the cable winch system requires substantially less oil than the known hydraulic cylinders (in the case of a hydraulically actuated winch) or no oil at all (in the case of an electrically actuated winch).In addition, a rigid securing structure enables the implementation of longer lengths of the intercepting support, so that contact between the cantilever and the intercepting support can take place even at a smaller defined cantilever angle. As a result, the boom can be blocked or braked earlier and thus a greater danger zone can be covered.In a winch-based system, the same basic system of the fall-back prevention device with different cuts can also be used for different cases or different cranes. The change in shear is a relatively small intervention in the system. The braking force could be varied, for example, by adding or removing brake units (modular system).Furthermore, a rigid arresting support holds the boom in a fixed position relative to the guying frame, so that the formation of slack rope in the guying system is prevented.Finally, the susceptibility of winds to corrosion is substantially less than that of a cylinder, especially with respect to the piston rod. In the case of longer idle times, corrosion on the piston rod can occur in the case of hydraulic cylinders, as a result of which leaks and damage to the seals are promoted.In the present case, the details regarding the boom angle (e.g. large / small boom angle) relate in particular to the angle between the boom longitudinal axis and the horizontal.The defined boom angle can be in the range of 50-70°, preferably in the range of 50-60°, wherein defined boom angles of less than 50° or, depending on the structure of the crane, of more than 70° are also possible.Theoretically, a defined cantilever angle of less than 40°, less than 30°, less than 20°, less than 10° or even in the extreme case of up to 0° could be achieved with the fall-back prevention device according to the invention, wherein such a large secured danger area would be purchased by an increased weight of the fall-back prevention device. For this purpose, the arresting support can be fastened pivotably, for example, to the guying frame and / or have a shape bent downward or in the direction of the boom.The fall-back prevention device according to the invention is preferably designed such that the cantilever can be wound up to an angle of 90° (i.e. the secured danger area extends up to 90°).In one possible embodiment, it is provided that the intercepting support can be both actively retracted and actively extended by means of the cable winch system. During the tilting, the intercepting support actively moves out as well and is tracked synchronously to the boom until the boom falls below the defined boom angle. Conversely, the intercepting support is actively retracted by the cable winch system above the defined boom angle synchronously with the swinging-up boom.For this purpose, the cable winch system preferably comprises a cable winch designed as a traversing winch, which can be actuated in both directions. A cable is mounted on the winch and is not fastened at one end to the winch but at both ends to the catch support. By rotating the winch in one direction or the other, the catch support can be extended or retracted. By using a single winch to retract and extend the catch support, fewer components need to be installed. Preferably, the rope is guided over several deflection rollers to different ends of the catch support and fastened there. The winch system may further include cable tensioners to avoid slack rope. These can each comprise one or more further deflection rollers.Alternatively, the support may be retractable and extendable over two separate "normal" winch, one of the winch pulling the support in the desired direction, while the other winch unwinds the other cable to track movement of the support.In a further possible embodiment, it is provided that the intercepting support can be actively extended via the cable winch system and can be retracted only passively. The extension can take place via a normal cable winch. Passive retraction is effected in particular by the boom which is pivoted open by means of the guying or the retraction mechanism and which exerts a corresponding force on the intercepting support. For this purpose, the cable winch can be released for retraction, so that it can rotate freely, mediated by the tilting boom. Alternatively, the cable winch could also be operated with a defined counterpressure which does not damage the boom, prevents slack cable and ensures permanent contact with the boom.In a further possible embodiment, it is provided that a catch device is arranged on the boom, with which the catch support comes into contact when the defined boom angle is reached. This creates a defined contact surface between the catch support and the extension arm. The collecting device preferably has a funnel-shaped opening region into which an end of the collecting support facing away from the guy support retracts when the collecting device is in contact. This ensures that the intercepting support always correctly moves into the intercepting device. The collecting device can be arranged on the side of the boom facing the guying bracket.The catch device can be articulated on the boom, for example in order to make it possible to track the catch support in the vertical direction or to compensate for a vertical relative movement. Alternatively, the catcher may be fixedly attached to the boom, e.g. when using a curved catcher bracket.In a further possible embodiment, it is provided that the arresting support is pivotably mounted on the guy support in order to compensate for a vertical movement of a contact region of the boom which is contacted by the arresting support (this can be the aforementioned arresting device) when a pivoting movement of the boom above the defined boom angle is tracked. When the cantilever is pivoted, the contact region moves not only horizontally relative to the fastening point of the catch support, but also in the vertical direction. This must be compensated for when the intercepting support is adjusted. The intercepting support can in particular have a straight or linear shape.In order to compensate for the vertical movement of the contact region during the tracking, the intercepting support can be actively pivotable by means of an actuator about its mounting on the guy support, for example by means of a hydraulic cylinder which is extended or retracted in a controlled manner.Alternatively, according to a further possible embodiment, it can be provided that the intercepting support has a curved shape and is designed such that, when a pivoting movement of the cantilever above the defined cantilever angle is tracked, a vertical movement of a contact region of the cantilever which is contacted by the intercepting support (this can be the aforementioned intercepting device) corresponds to the vertical movement of an end section of the intercepting support which contacts the contact region. In other words, the intercepting support can be curved or bent in such a way that, when the intercepting support is retracted and extended, its end region describes exactly such an arc that it follows the contact region of the cantilever during the tilting up and down. As a result, the arresting support does not have to be adjusted in the vertical direction in addition, but can be mounted on the guy support in a non-pivotable manner, for example. The catch support is bent in particular downwards.In a further possible embodiment, it is provided that the fall-back prevention device comprises a pressure accumulator which is "charged" when the intercepting support is retracted and discharges again when the intercepting support is extended and thereby supports the cable winch system which extends the intercepting support. The pressure accumulator can be a hydraulic accumulator or, as is preferred, a gas pressure accumulator.In a further possible embodiment, it is provided that the fall-back prevention device comprises a braking device which, when activated, actively or passively brakes retraction of the intercepting support. Preferably, the intercepting support is braked to a standstill. The activation of the brake device is preferably carried out automatically by a control device (e.g. the crane controller) upon detection of a critical state (e.g. a load break), but can also be carried out as standard whenever the boom is not moved (i.e. activation of the brake device upon a stop of the boom).The brake device may comprise an active force-locking brake system which is actuated hydraulically, electrically or pneumatically. Alternatively or additionally, the brake device can comprise an active form-fit brake system which is actuated hydraulically, electrically or pneumatically. It is likewise conceivable for the brake device to comprise a passive brake system which brakes after activation without a further application of force and, for example, varies the braking force as a function of the load (for example by means of a self-locking wedge).In a further possible embodiment, it is provided that the crane comprises a detection device with a sensor system for detecting a critical state of the crane, in particular a load stall. The sensor system can comprise at least one acceleration sensor, which can be arranged, for example, on the boom, on the guy support, on a lifting cable or load-receiving means or at any other desired location on the support structure. It is likewise conceivable for the acceleration sensor to be part of the fall-back prevention device. Alternatively or additionally to the mentioned acceleration sensor, other sensors can be present, for example at least one inertial measurement 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 in order to monitor the crane and to detect critical states.The crane preferably further comprises a control unit which receives data from the detection device or the sensor system and is configured to recognize a critical state on the basis of the received data and, in response thereto, to actuate a locking device or a braking device of the fall-back prevention device, such that the boom is braked or blocked above the defined boom angle. The control unit can be the crane controller or a separate control unit.Alternatively to a selectively braked solution which requires a detection of a critical state, the brake can always be activated if the boom is not tilted. In this case, a sensor system for detecting a critical state can be dispensed with.In a further possible embodiment, it is provided that the fall-back prevention device comprises at least one actuating unit with a holder fastened to the guy support, in which holder the interception support is displaceably mounted, wherein the cable winch system mentioned is part of the actuating unit. The actuating unit supports the intercepting support in particular on the guying bracket. In the case of a linear or straight intercepting support, which has to be tracked vertically when the boom is pivoted, the actuating unit can comprise an actuator, which actively pivots the intercepting support or the holder when the boom is pivoted.In a further possible embodiment, it is provided that the actuating unit comprises the mentioned brake device. The brake device can be integrated into the holder or can be part of the holder. The braking device can comprise, for example, one or more braking elements which brake the intercepting support in a force-fitting or form-fitting manner or else passively, as described above. Alternatively, the brake device can be integrated into the cable winch system. For example, the arresting support can be braked by braking the corresponding cable winch. The brake device can represent an active brake system with a singly or multiply cut-in cable winch.In a further possible embodiment, it is provided that the intercepting support has a bent shape, as described above, wherein the holder has a bent shape in order to receive the bent intercepting support in a displaceable manner. In this case, the holder can be immovably fastened to the guy support.In a further possible embodiment, it is provided that the fall-back prevention device comprises at least two intercepting supports which can preferably be moved in and / or out via separate cable winch systems. Exactly two arresting supports can be provided, which can preferably be mounted laterally or in the lateral regions of the guy support. Alternatively, more than two intercepting supports can be provided, in particular a multiple of two intercepting supports. These can be arranged, for example, one above the other on the guying block and ensure an even more effective braking of the boom, in particular in cranes with a very large and heavy boom.In a further possible embodiment, it is provided that the support structure comprises a rotary platform mounted on a substructure such that it can rotate about a vertical axis of rotation, on which platform the boom, the guying bracket and the fall-back securing 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 hull.The present invention further relates to a fall-back prevention device for a crane according to the invention. The same properties and advantages are obviously obtained as for the crane according to the invention. All embodiments and design options of the fall-back prevention device described with respect to the crane therefore also apply to the fall-back prevention device according to the invention, in any combination.Further features, details and advantages of the invention are evident from the exemplary embodiments explained below with reference to the figures. The following are shown: FIG. 1 : a perspective view of a first exemplary embodiment of the crane according to the invention, wherein only the support structure with the jib is shown; FIGS. 2-3 : Side views of the crane according to the exemplary embodiment of FIG. 1 with different boom positions; FIGS. 4-5 are a perspective view and a side view of a catch support according to an embodiment; and FIGS. 6 to 7 are side views of the crane according to a second exemplary embodiment with different boom positions.FIG. 1 shows a perspective view of an exemplary embodiment of the crane 10 according to the invention in the form of an offshore heavy-duty crane, wherein the ship hull is not illustrated. The crane 10 comprises a support structure 11 with a substructure 12 (in this exemplary embodiment connected to the ship hull, not shown) and a rotary platform 14 mounted on the substructure 12 such that it can rotate about a vertical axis of rotation.The crane 10 comprises a boom 16 which is pivotably articulated to the rotary platform 14 about a horizontal luffing axis. In the exemplary embodiment shown, the boom 16 is designed as a lattice mast boom with two boom strings running towards a boom head 13, in order to provide the boom 16 with the necessary stability for the considerable loads to be lifted. The jib head 13 has a plurality of deflecting rollers over which a lifting cable (not shown) which has been repeatedly cut in is guided and connected to a hook bottle (likewise not shown).A guying frame 18 is fastened to the rotary platform 14, at the end of which there are a plurality of deflection rollers, via which a guy stranding 19 (= guying) is guided to the jib head 13. By means of a drawing-in unit, which can comprise one or more guy cable jacks 15 arranged at the rear of the rotary platform 14 (cf. FIG. 3 ), the boom 16 can be wound and unwound.Due to the rolling behavior of the ship, in critical situations, in particular in the event of a load stall, the boom 16 can swing back in the direction of the guy support 18, which can cause considerable damage. In order to prevent this, the crane 10 comprises a fall-back prevention device 20 which is arranged on the guy support 18 and is configured to intercept and brake or stop a swinging back of the boom 16.In the embodiment of FIG. 1, the fall-back prevention device 20 comprises two intercepting supports 22, which are designed as linear supports running parallel to one another and rigid supports. FIGS. 4-5 show one of the intercepting supports 22 in a perspective view and in a lateral view.The rigid arresting supports 22 are each mounted on the guying frame 18 via an actuating unit 24 and have an end 23 which points toward the boom 16 and which are in contact with the side of the boom 16 pointing toward the guying frame 18 above a defined boom angle. The length of the intercepting supports 22 therefore determines the defined boom angle. On the side of the boom 16 facing the guy support 18 there are catching devices 17 which form the contact regions for the ends 23 of the catching supports 22 and, in the exemplary embodiment shown, have a funnel-shaped receptacle which is open towards the guy support 18 and which ensure a proper retraction of the catching supports 22 into the receiving devices 17. In the exemplary embodiment shown, the defined boom angle is approximately 60° with respect to the horizontal, but can also be greater or smaller depending on the type of crane and the design of the arresting supports 22.The actuating units 24 each comprise a holder 25 in which the respective guy support 22 is displaceably mounted. In addition, the actuating units 24 each comprise a cable pull system 30, by means of which the respective guy support 22 can be extended and retracted. The retraction refers to a movement of the guy support 22 away from the boom 16 and the extension to the opposite movement in the direction of the boom 16.In the embodiment shown in FIGS. 4-5, the cable system 30 comprises a single cable winch 32 which is designed as a traversing winch and can thus move the intercepting support 22 in both directions. For this purpose, the two ends of the cable 34 wound on the traversing winch 32 are fastened to the opposite ends of the intercepting support 22. The cable 34 is guided via a rear deflection pulley 36 of the cable system 30 to the rear end of the intercepting support 22 and via a front deflection pulley 37 of the cable system 30 to the front end of the intercepting support 22. Furthermore, the cable system 30 comprises a front cable tensioner 39 and a rear cable tensioner 38, which each have a further deflection pulley and ensure that the cable 34 is always tensioned. Depending on the loads occurring and the design of the crane 10, the cable winch 32 can be tensioned once or several times.The intercepting supports 22 can be actively retracted and actively extended via the cable jacks 32. The cable winch 32 is controlled and / or regulated (for example via the crane controller) in such a way that the arresting supports 22 are tracked to the movement of the boom 16 above the defined boom angle, so that the boom 16 can be freely tilted up and down above the defined boom angle in normal operation, but the arresting supports 22 are nevertheless always in contact with the arresting devices 17.The tracking of the intercepting supports 22 is illustrated in FIGS. 2-3. These show the crane 10 in a lateral view in two different boom positions. FIG. 2 shows the boom 16 in a position in which the boom angle corresponds to the defined boom angle, from which the fall-back prevention device 20 ensures the movement of the boom 16, and in which the intercepting supports 22 are extended to the maximum extent. FIG. 3 shows the boom 16 in its maximum up-tilted position, in which the catch supports 22 are maximally retracted.If a critical state of the crane 10 now occurs, such as a load stall in which the boom 16 suddenly swings back in the direction of the guy support 18, the retraction movement of the guy supports 22 can be braked via brake devices 26 of the actuating units 24 and finally stopped in order to prevent a collision between boom 16 and guy support 18. The brake devices 26 can comprise brake blocks, ratchets and / or a connecting rod, for example, as brake elements.The brake devices 26 may include an active frictional or positive brake system that may be hydraulically, electrically, or pneumatically actuated. If a critical state is detected, the braking devices 26 are activated and a force-fit or form-fit braking takes place. Alternatively, the intercepting supports 22 can be actively braked via the singly or multiply cut-in cable winch 32.Alternatively, a passive brake system could also be provided, which achieves a corresponding braking effect, for example, via self-locking wedges. Such a passive brake system must also be activated in order to brake or block the retraction movement of the intercepting supports 22.As can be seen in FIGS. 2-3, during a luffing movement of the boom 16, the catching devices 17 move not only in the horizontal direction but also in the vertical direction relative to the actuating units 24. For this purpose, the catching devices 17 can have a correspondingly configured receiving region which enables tilting of the catching supports 22 relative to the catching devices 17. In addition, the actuating units 24 can be actively pivotable relative to the guying frame 18 via actuators, for example individually pivotable. FIG. 1 shows an embodiment in which the actuating units 24 are mounted on a carrier 21 running parallel to the boom tilting axis, which can be pivoted in an actuator-based manner as a whole. The control and / or regulation of the actuators for pivoting the interception supports 22 can be effected via the same control unit (e.g. the crane controller) as the control / regulation of the cable winch 32.In an active braking system, a detection of the critical state (e.g. a load loss or a rolling movement of the ship) is required. This can be done via a sensor system of a detection device of the crane 10, which can be based on different sensors, e.g. acceleration sensors, proximity sensors, mechanical limit switches and / or pressure sensors. The sensor system is in particular connected to a control unit which controls or activates the cable winch 32 and / or the brake devices 26.In the exemplary embodiment shown, the intercepting braces 22 actively extend to the defined boom angle and also actively retract. Alternatively, passive retraction can take place (in particular by the tilting boom 16), so that no traversing winch 32 has to be used.FIGS. 6 to 7 show an alternative exemplary embodiment of the crane 10 according to the invention, in which the arresting supports 22 are not formed in a straight or linear manner but in a curved manner. These are curved or bent downward. As a result, the ends 23 of the catch supports 22 facing the catching devices 17 describe an arc during the tracking of the boom 16 which follows the movement of the catching devices 17. As a result, the intercepting supports 22 do not need to be tracked or pivoted in the vertical direction. The actuating units 24 can therefore be firmly connected to the guying block 18, but have to be designed (for example by means of a correspondingly bent holder 25) such that the bent interception supports 22 are displaceably guided or mounted therein.List of reference numbers:10 Crane 11 Support structure 12 Substructure 13 Boom head 14 Rotary platform 15 Guy cable winch / drawing-in unit 16 Boom 17 Catching device 18 Guy bracket 19 Guying 20 Fall-back prevention device 21 Support 22 Catching support 23 End 24 Actuating unit 25 Holder 26 Braking device 30 Cable winch system 32 Cable winch 34 Cable 36 Deflection roller 37 Deflection roller 38 Cable tensioner 39 Cable tensioner

Claims

Crane (10) comprising a support structure (11), a boom (16) connected to the support structure (11) such that it can be pivoted about a horizontal luffing axis, a guying bracket (18) connected to the support structure (11), by means of which the boom (16) is guyed by means of a length-variable guying (19), and a fall-back prevention device (20) arranged on the guying bracket (18), which is configured to block or brake tilting of the boom (16) in the direction of the guying bracket (18) in a critical state of the crane (10), in particular in the event of a load break, wherein the fall-back prevention device (20) comprises at least one arresting support (22), with which the boom (16) comes into contact during the jacking at a defined boom angle, characterized in that the arresting support (22) is designed as a rigid element, which is guided along the boom (16) above the defined boom angle and can be actively moved in and / or out relative to the guy support (18) by means of a cable winch system (30) of the fall-back prevention device (20).Crane (10) according to claim 1, wherein the arresting support (22) can be actively moved in and out 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 is guided in particular over a plurality of deflecting rollers (36) to different ends of the arresting support (22) and is fastened there.The crane (10) of claim 1, wherein the interception support (22) is actively extendable via the winch system (30), and wherein the interception support (22) is passively retractable, in particular by the tilting boom (16).Crane (10) according to one of the preceding claims, wherein a collecting device (17) is arranged on the jib (16), with which the collecting support (22) comes into contact when the defined jib angle is reached, wherein the collecting device (17) preferably has a funnel-shaped opening region into which an end of the collecting support (22) facing away from the guying frame (18) enters when the collecting device (17) is in contact.The crane (10) according to any one of the preceding claims, wherein the arresting support (22) is pivotably mounted on the guy support (18) in order to compensate for a vertical movement of a contact region of the jib (16) which is contacted by the arresting support (22) during a pivoting movement of the jib (16) above the defined jib angle, wherein the arresting support (22) preferably has a linear shape.The crane (10) according to any one of claims 1 to 4, wherein the interception support (22) has a curved shape and is configured such that, during a pivoting movement of the jib (16) above the defined jib angle, a vertical movement of a contact region of the jib (16) which is contacted by the interception support (22) corresponds to the vertical movement of an end section of the interception support (22) which contacts the contact region, wherein the interception support (22) is preferably not pivotably mounted on the guy support (18).Crane (10) according to one of the preceding claims, wherein the fall-back prevention device (20) comprises a pressure accumulator, in particular a gas pressure accumulator, which is charged when the interception support (22) is retracted and supports the cable winch system (30) when the interception support (22) is extended.Crane (10) according to one of the preceding claims, wherein the fall-back prevention device (20) comprises a braking device (26) which, when activated, actively or passively brakes retraction of the arresting support (22), wherein the activation preferably takes place automatically by a control device when a critical state is detected or always when the boom (16) is stopped, wherein the braking device (26) preferably comprises an active force-locking or form-locking brake system or a passive brake system which is based in particular on a self-locking wedge.The crane (10) according to any one of the preceding claims, further comprising a detection device with a sensor system for detecting a critical state 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 prevention device (20) in the case of a detected critical state.Crane (10) according to one of the preceding claims, wherein the fall-back prevention device (20) comprises at least one actuating unit (24) with a holder (25) fastened to the guy support (18), in which holder the interception support (22) is displaceably mounted, wherein the actuating unit (24) comprises the cable winch system (30).Crane (10) according to the preceding claim and further developed by the features of claim 8, wherein the actuating unit (24) comprises the brake device (26), wherein the brake device (26) is preferably integrated into the holder (25) or into the cable winch system (30).The crane (10) of any of the two preceding claims and further developed by the features of claim 5, wherein the bracket (25) has a curved shape to slidably receive the curved catch support (22).Crane (10) according to one of the preceding claims, wherein the fall-back prevention device (20) comprises at least two arresting supports (22), which can preferably be moved in and / or out via separate cable winch systems (30).The crane (10) according to any one of the preceding claims, wherein the support structure (11) comprises a rotary platform (14) which is mounted on a substructure (12) such that it can rotate about a vertical axis of rotation and on which the boom (16), the guying block (18) and the fall-back prevention 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 hull.Fall-back prevention device (20) for a crane (10) according to one of the preceding claims.

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