Crane with active rollback protection

Abstract

The present invention relates to a crane comprising: a load bearing structure; a boom connected to the load bearing structure so as to be pivotable about a horizontal variable amplitude axis; the inhaul cable frame is connected to the bearing structure, and the suspension arm is tensioned through the inhaul cable frame by means of an inhaul cable with the variable length; the invention relates to a crane having a suspension arm, a cable frame, and a fallback protection device arranged on the cable frame and configured to prevent or brake tilting of the suspension arm towards the cable frame in a critical state of the crane, in particular in the event of a load drop, in which the fallback protection device comprises at least one stabilizing strut, the boom is in contact with the at least one stabilizing strut when tilted rearward for a defined boom angle. According to the invention, the stabilizing strut is configured as a rigid element which follows the boom when the defined boom angle is exceeded and which can be actively inserted and / or withdrawn relative to the cable frame by means of a cable winch system of the retraction protection device. The invention also relates to a corresponding rollback protection device.

Description

Technical Field

[0001] The present invention relates to a crane and to a retraction protection device for such a crane. Background Art

[0002] Such a crane is typically configured as a heavy-duty ship crane or a heavy-duty offshore crane and has a boom that can be tilted about a horizontal axis and tensioned via a length-variable cable via a cable support. The boom is tilted forward and backward by actuating the cable via a telescopic device.

[0003] In such a crane, due to the roll behavior of the ship that may occur, for example, in the case of load shedding, load loss, or movement on the deck, the boom may swing backward toward the cable support, which may cause damage to the boom and the cable support. For this reason, it is known from the prior art to equip such cranes with hydraulic retraction protection cylinders that contact the boom at a specified maximum boom angle and prevent or brake the backward swing of the boom in the case of load shedding.

[0004] The disadvantage of these systems is that the hydraulic cylinders used have a large differential volume and thus require a large amount of oil that must be delivered in a short time. In this case, the cylinder needs to be coordinated with the entire system in terms of maximum length and holding force.

[0005] In addition, the hydraulic cylinder is prone to buckling due to its design, which is why relatively large and heavy components need to be installed. For this reason, the maximum length of the cylinder is usually limited, which means that the entire dangerous range cannot usually be covered (i.e., the retraction protection only intervenes at relatively large boom angles).

[0006] In addition, when the boom is supported, the oil is compressed and thus the distance between the boom and the cable support is reduced because the cylinder is supported on a compressible oil column. This inevitably leads to slack in the cable of the cable or the telescopic device. Depending on the roll movement of the ship, the boom may enter a free-fall phase, which may cause the boom structure, the telescopic device, and / or other components in the load path to become overloaded or malfunction. Summary of the Invention

[0007] Therefore, the object of the present invention is to provide a general crane including a retraction protection device in which the above-mentioned disadvantages do not occur and the degree of damage is minimized in the case of load shedding.

[0008] According to the present invention, this problem is solved by a crane according to one aspect of the present invention and a retraction protection device according to another aspect of the present invention. Advantageous embodiments of the present invention are visible in other aspects of the present invention and the following description.

[0009] Accordingly, a crane is proposed, which crane comprises: a load-bearing structure; a jib, which is connected to the load-bearing structure so as to be pivotable about a horizontal luffing axis; a guy frame, which is connected to the load-bearing structure; and a retraction protection device, which is arranged on the guy frame. The jib is tensioned via the guy frame (also known as the A-frame) by means of a length-variable cable system, in particular cable ropes. As described at the beginning, the jib can in particular be tilted forwards and backwards by changing the length of the cable system by means of a telescopic device. The jib can be a lattice jib. Alternatively, a box jib can also be envisaged.

[0010] The retraction protection device is configured to prevent or brake the tilting of the jib towards the guy frame in a critical state of the crane, in particular in the case of load shedding. This prevents damage to the guy frame and the jib, since the jib is prevented or braked by the retraction protection device before reaching the guy frame. For this purpose, the retraction protection device comprises at least one stabilizing strut, which the jib contacts when tilting backwards when the jib reaches a defined jib angle. Below the defined jib angle, the jib does not contact the stabilizing strut (hereinafter, for the sake of simplicity, only the "stabilizing strut" is mentioned, but this should always mean at least one stabilizing strut).

[0011] According to the invention, the stabilizing strut is not configured as, for example, a piston-cylinder unit, but as a rigid element, such as a steel beam. The stabilizing strut is also not fixedly fastened to the guy frame, but actively or passively follows the jib beyond the defined jib angle. For this purpose, beyond the defined jib angle, when the jib tilts backwards, the stabilizing strut is inserted so that the stabilizing strut always contacts the jib. Conversely, beyond the defined jib angle, when the jib tilts forwards, the stabilizing strut is withdrawn in order to maintain contact with the jib. For this purpose, the retraction protection device comprises a cable winch system by means of which the stabilizing strut can be actively inserted and / or actively withdrawn relative to the guy frame.

[0012] The fact that the stabilizing strut follows the jib ensures that beyond the defined jib angle, in the event of a critical state, such as load shedding, the stabilizing strut and thus the jib can be directly prevented or braked. Accordingly, the dangerous range covered by the retraction protection device is specified by the defined jib angle, and thus this defined jib angle should be as small as possible (in order to protect the largest possible angular range). According to the invention, this can be achieved because configuring the stabilizing strut as a rigid element allows a longer length and thus a larger dangerous range to be covered. Accordingly, a defined jib angle of 60° can be achieved, but smaller angles, such as 50° or less, can also be achieved (i.e., in the latter case, even if the jib angle to the horizontal line is 50° or less, the retraction protection device according to the invention will be active).

[0013] In normal operation, the stabilizing strut follows the jib particularly freely, i.e., without exerting a significant force on the jib. In normal operation, the stabilizing strut can thus also tilt freely forwards and backwards, particularly within the danger range (i.e., beyond a defined jib angle). The stabilizing strut is only inserted in a critical state and thus prevents or brakes the further backward tilting of the jib beyond the defined jib angle.

[0014] Compared to a solution based on a hydraulic cylinder, the solution according to the invention has several advantages, wherein the stabilizing strut is inserted and / or withdrawn by a cable winch. For example, at least one cable winch of the cable winch system requires much less oil (in a hydraulically actuated winch) or no oil at all (in an electrically actuated winch) than a known hydraulic cylinder.

[0015] Furthermore, the rigid fixing structure allows for a stabilizing strut of a greater length to be realized, such that even at a lower defined jib angle, the jib and the stabilizing strut can come into contact. Thus, the backward tilting of the jib can be prevented or braked earlier and thus a greater danger range can be covered.

[0016] In a winch-based system, the same basic system of the back-off protection device can also be used for different scenarios or different rope winding (Einscherungen) settings of different cranes. The change of the rope winding is a relatively minor intervention in the system. For example, the braking force can be changed by adding or removing a braking unit (modular system).

[0017] Furthermore, the rigid stabilizing strut holds the jib in a fixed position relative to the cable support frame, such that the slackening of the cables in the cable system is prevented.

[0018] Finally, compared to a cylinder, in particular a piston rod, a winch is less susceptible to corrosion. After a relatively long downtime, corrosion can occur on the piston rod in the hydraulic cylinder, which makes it more likely that the seals will start to leak and be damaged.

[0019] In the present case, the indication of the jib angle (e.g., a greater / smaller jib angle) is particularly related to the angle between the longitudinal jib axis and the horizontal line.

[0020] The defined jib angle can be in the range of 50° to 70°, preferably in the range of 50° to 60°, but the defined jib angle can also be less than 50° or, depending on the construction of the crane, greater than 70°.

[0021] In theory, the retraction protection device according to the present invention can achieve a defined boom angle of less than 40°, less than 30°, less than 20°, less than 10° or even up to 0° in extreme cases. However, protecting such a large dangerous range will come at the cost of increasing the weight of the retraction protection device. For this purpose, the stabilizing strut can, for example, be pivotally fastened to the cable support and / or can have a shape that bends downward or towards the boom.

[0022] The retraction protection device according to the present invention is preferably configured such that the boom can be tilted backward by an angle of up to 90° (i.e., the protected dangerous range reaches 90°).

[0023] In a possible embodiment, it is provided that the stabilizing strut can be actively inserted and actively withdrawn by means of a cable winch system. When the boom tilts forward, the stabilizing strut is actively withdrawn with it and synchronously follows the boom until the boom drops below the defined boom angle. Conversely, the stabilizing strut is synchronously and actively inserted towards the boom that tilts backward beyond the defined boom angle by means of the cable winch system.

[0024] For this purpose, the cable winch system preferably includes a cable winch configured as a transverse winch, which can be actuated in two directions. The cable is mounted on the cable winch. The free end of the cable is not fastened to the cable winch, but both ends are fastened to the stabilizing strut. By rotating the cable winch in one direction or the other, the stabilizing strut can be inserted or withdrawn. By using a single winch to insert and withdraw the stabilizing strut, fewer components need to be installed. The cable is preferably guided to different ends of the stabilizing strut through a plurality of guide wheels and fastened there. The cable winch system can also include a cable winder to avoid cable slack. They can each include one or more additional guide wheels.

[0025] Alternatively, the stabilizing strut can be inserted and withdrawn via two separate "normal" cable winches, where one of the cable winches pulls the stabilizing strut in the desired direction, while the other cable winch unwinds the other cable so that it follows the movement of the stabilizing strut.

[0026] In another possible embodiment, it is provided that the stabilizing strut can be actively withdrawn and can only be passively inserted via the cable winch system. The retraction can be carried out via a normal cable winch. The passive insertion is particularly carried out by the boom tilting backward by means of a cable system or a telescopic device, which exerts a corresponding force on the stabilizing strut. For this purpose, the cable winch can be disengaged for insertion so that it can rotate freely, which is caused by the boom tilting backward. The cable winch can also alternatively be operated by a defined counterpressure that does not damage the boom, prevents cable slack, and ensures permanent contact with the boom.

[0027] In another possible embodiment, it is provided that a receiving device is arranged on the jib, and when a defined jib angle is reached, the stabilizing strut contacts this device. This creates a defined contact surface between the stabilizing strut and the jib. The receiving device preferably has a funnel-shaped opening area into which the end of the stabilizing strut facing away from the cable support is inserted when contacting the receiving device. This ensures that the stabilizing strut is always correctly inserted into the receiving device. The receiving device can be arranged on the side of the jib facing the cable support.

[0028] The receiving device can be fastened to the jib in an articulated manner, for example, to allow the stabilizing strut to follow the jib in the vertical direction or to compensate for vertical relative movement. Alternatively, the receiving device can be firmly fastened to the jib, for example when using a bent stabilizing strut.

[0029] In another possible embodiment, it is provided that the stabilizing strut is pivotally mounted on the cable support in order to compensate for the vertical movement of the contact area of the jib contacted by the stabilizing strut (which can be the above-mentioned receiving device) when following the pivotal movement of the jib beyond a defined jib angle. When the jib pivots, the contact area not only moves horizontally relative to the fastening point of the stabilizing strut, but also moves in the vertical direction. This must be compensated for when the stabilizing strut follows the jib. The stabilizing strut can particularly have a straight or linear shape.

[0030] In order to compensate for the vertical movement of the contact area when following, the stabilizing strut can be actively pivoted around its mounting on the cable support by means of an actuator (for example by means of a hydraulic cylinder), and the actuator is inserted or withdrawn in a controlled manner.

[0031] Alternatively, according to another possible embodiment, it is provided that the stabilizing strut has a bent shape and is configured such that when following the pivotal movement of the jib beyond a defined jib angle, the vertical movement of the contact area of the jib contacted by the stabilizing strut (which can be the above-mentioned receiving device) corresponds to the vertical movement of the end portion of the stabilizing strut in contact with the contact area. In other words, the stabilizing strut can be bent or curved such that when inserting and withdrawing the stabilizing strut, the end region of the stabilizing strut precisely depicts the curve of the contact area of the jib that follows when it tilts backward or forward. Thus, for example, the stabilizing strut does not need to also follow in the vertical direction, but can be non-pivotally mounted on the cable support. Here, the stabilizing strut is particularly bent downward.

[0032] In another possible embodiment, it is provided that the retraction protection device includes an accumulator that is "pressurized" when the stabilizing strut is inserted and depressurized again when the stabilizing strut is retracted, and thus assists the cable winch system for retracting the stabilizing strut. The accumulator can be a hydraulic accumulator or preferably a gas accumulator.

[0033] In another possible embodiment, it is provided that the fallback protection device includes a braking device which, when activated, actively or passively brakes the insertion of the stabilising strut. In this case, the stabilising strut is preferably braked to a standstill. The braking device is preferably automatically activated by a control device (e.g. a crane controller) when a critical state (e.g. load shedding) is recognised, but can also be activated as standard when the jib is not moving (i.e. when the jib has stopped, the braking device is activated).

[0034] The braking device can include an actively friction braking system actuated hydraulically, electrically or pneumatically. Alternatively or additionally, the braking device can include an actively rigid engagement braking system actuated hydraulically, electrically or pneumatically. It is also conceivable that the braking device includes a passive braking system which brakes after activation without any additional force effect and changes the braking force, for example, depending on the load (e.g. by means of a self-locking wedge).

[0035] In another possible embodiment, it is provided that the crane includes a detection device which includes a sensor system for detecting critical states of the crane, in particular load shedding. The sensor system can include at least one acceleration sensor which can be arranged, for example, on the jib, the guying frame, the winch cable or the load receiving member, or at any other point on the load-bearing structure. It is also conceivable that the acceleration sensor is part of the fallback protection device. As an alternative or supplement to the acceleration sensor, other sensors can be provided, 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 points in order to monitor the crane and identify critical states.

[0036] The crane preferably also includes a control unit which receives data from the detection device or the sensor system and is configured to identify critical states based on the received data and, in response thereto, to actuate the locking device or the braking device of the fallback protection device such that the jib is braked or prevented from exceeding a defined jib angle. The control unit can be a crane controller or a separate control unit.

[0037] As an alternative to the selective braking solution which requires the identification of critical states, the brake can be activated as long as the jib is not tilted. In this case, the sensor system for identifying critical states can be omitted.

[0038] In another possible embodiment, it is provided that the fallback protection device comprises at least one actuating unit, which at least one actuating unit comprises a mounting which is fastened to the guying frame and in which a stabilizing strut is movably mounted, wherein the cable winch system is part of the actuating unit. The actuating unit mounts the stabilizing strut, in particular, on the guying frame. In the case of a linear or straight stabilizing strut which must follow vertically when the boom pivots, the actuating unit may comprise an actuator which actively pivots the stabilizing strut or the mounting when the boom tilts.

[0039] In another possible embodiment, it is provided that the actuating unit comprises the braking device. In this case, the braking device may be integrated in the mounting or may be part of the mounting. The braking device may comprise, for example, one or more braking elements which brake the stabilizing strut in a frictional or positive engagement manner or passively, as described above. Alternatively, the braking device may be integrated in the cable winch system. For example, the stabilizing strut may be braked by braking the corresponding cable winch. The braking device may be an active braking system comprising a single-wrap or multi-wrap cable winch.

[0040] In another possible embodiment, it is provided that the stabilizing strut has a bent shape, as described above, wherein the mounting has a bent shape in order to movably receive the bent stabilizing strut. In this case, the mounting may be fastened immovably to the guying frame.

[0041] In another possible embodiment, it is provided that the fallback protection device comprises at least two stabilizing struts which may preferably be inserted and / or withdrawn via separate cable winch systems. Exactly two stabilizing struts may be provided which may preferably be mounted laterally or in the lateral region of the guying frame. Alternatively, more than two stabilizing struts, in particular multiples of two stabilizing struts, may be provided. For example, they may be arranged one above the other on the guying frame and ensure more effective braking of the boom, in particular in cranes with a very large and heavy boom.

[0042] In another possible embodiment, it is provided that the load-bearing structure comprises a slewing platform which is mounted on the lower structure so as to be rotatable about a vertical axis of rotation, and the boom, the guying frame and the fallback protection device are arranged on the slewing platform. The crane according to the invention is preferably a ship-mounted crane, in particular a heavy-duty offshore crane or a heavy-duty ship-mounted crane, wherein the lower structure is connected to the hull of the ship.

[0043] The present invention also relates to a retraction protection device for a crane according to the present invention. This clearly results in the same properties and advantages as the crane according to the present invention. Accordingly, all embodiments and configuration options of the retraction protection device described with respect to the crane can also be applied, in any combination, to the retraction protection device according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Additional features, details, and advantages of the present invention are visible in the following exemplary embodiments explained with reference to the drawings, in which:

[0045] Figure 1 is a perspective view of a first exemplary embodiment of a crane according to the present invention, in which only the load-bearing structure including the boom is shown;

[0046] Figures 2 to 3 is from Figure 1 a side view of a crane according to an exemplary embodiment of, in which the boom is in a different position;

[0047] Figures 4 to 5 are a perspective view and a side view, respectively, of a stabilizing strut according to an exemplary embodiment; and

[0048] Figures 6 to 7 is a side view of a crane according to a second exemplary embodiment, in which the boom is in a different position. DETAILED DESCRIPTION

[0049] Figure 1 is a perspective view of an exemplary embodiment of a crane 10 in the form of a heavy-duty offshore crane according to the present invention, in which the hull of the ship is not shown. The crane 10 includes a load-bearing structure 11 having a lower structure 12 (which, in this exemplary embodiment, is connected to the hull of the ship (not shown)) and a slewing platform 14 that is mounted on the lower structure 12 so as to be rotatable about a vertical axis of rotation.

[0050] The crane 10 includes a boom 16 that is hinged to the slewing platform 14 so as to be pivotable about a horizontal luffing axis. In the exemplary embodiment shown, the boom 16 is configured as a lattice boom that includes two boom beams that taper towards the boom head 13 so as to give the boom 16 the required stability to lift a relatively large load. The boom head 13 has a plurality of guide wheels around which a multi-wire winch cable (not shown) is guided and connected to a lifting block (also not shown).

[0051] The guy frame 18 is fastened to the slewing platform 14, and a plurality of guide wheels are positioned at the ends of the guy frame. The guy cable 19 (= guy system) is guided on the plurality of guide wheels to the boom head 13. The boom 16 can be tilted forwards and backwards by means of a telescopic device which can include one or more guy cable winches 15 arranged at the rear of the slewing platform 14 (see Figure 3 ).

[0052] Due to the rolling behavior of the ship, in critical situations, especially in the case of load shedding, the boom 16 can swing backwards towards the guy frame 18, which can cause significant damage. To prevent this, the crane 10 includes a retraction protection device 20 which is arranged on the guy frame 18 and is configured to catch and brake or prevent the boom 16 from swinging backwards.

[0053] In Figure 1 the exemplary embodiment, the retraction protection device 20 includes two stabilizing struts 22 which are configured as linear rigid beams extending parallel to each other. Figures 4 to 5 are a perspective view and a side view of one of the stabilizing struts 22, respectively.

[0054] The rigid stabilizing 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, beyond a defined boom angle, comes into contact with the side of the boom 16 pointing towards the guy frame 18. Thus, the length of the stabilizing struts 22 determines the defined boom angle. Receiving devices 17 are located on the side of the boom 16 pointing towards the guy frame 18, which receiving devices form the contact area for the ends 23 of the stabilizing struts 22 and have in the exemplary embodiment shown a funnel-shaped receptacle which opens towards the guy frame 18 and ensures correct insertion of the stabilizing struts 22 into the receiving devices 17. In the exemplary embodiment shown, the defined boom angle is approximately 60° relative to the horizontal, but can also be larger or smaller depending on the type of crane and the configuration of the stabilizing struts 22.

[0055] The actuating units 24 each include a mounting 25 in which the associated stabilizing strut 22 is movably mounted. In addition, the actuating units 24 each include a cable winch system 30 by means of which the associated stabilizing strut 22 can be inserted and withdrawn. In this case, insertion involves movement of the stabilizing strut 22 away from the boom 16 and withdrawal involves movement in the opposite direction towards the boom 16.

[0056] In Figures 4 to 5In the exemplary embodiment shown, the cable winch system 30 includes a single cable winch 32 which is configured as a traversing winch (Traversierwinde) and can thus move the stabilizing strut 22 in two directions. For this purpose, the two ends of the cable 34 wound around the traversing winch 32 are fastened to opposite ends of the stabilizing strut 22. The cable 34 is guided towards the rear end of the stabilizing strut 22 via the rear guide pulley 36 of the cable winch system 30 and towards the front end of the stabilizing strut 22 via the front guide pulley 37 of the cable winch system 30. Furthermore, the cable winch system 30 includes a front cable winder 39 and a rear cable winder 38, each having a further guide pulley and ensuring that the cable 34 is always tensioned. Depending on the load occurring and the configuration of the crane 10, the cable winch 32 can be single-wound or multi-wound.

[0057] The stabilizing strut 22 can be actively inserted and actively withdrawn via the cable winch 32. In this case, the cable winch 32 is controlled and / or adjusted (for example, by means of the crane controller) such that beyond a defined boom angle, the stabilizing strut 22 follows the movement of the boom 16, such that in normal operation, the boom 16 can tilt freely forwards and backwards beyond the defined boom angle, but the stabilizing strut 22 still always remains in contact with the receiving device 17.

[0058] In Figures 2 to 3 the following figures, the following figures show the stabilizing strut 22 following the boom. These figures are side views of the crane 10 with the boom in different positions. Figure 2 shows the boom 16 in a position where the boom angle corresponds to the defined boom angle, from which position, the retraction protection device 20 protects the movement of the boom 16 and the stabilizing strut 22 is withdrawn to the maximum extent. Figure 3 shows the boom 16 in the maximum rearward tilt position, in which position the stabilizing strut 22 is inserted to the maximum extent.

[0059] If a critical state of the crane 10 subsequently occurs, such as load shedding, in which the boom 16 suddenly swings backwards towards the guying frame 18, the insertion movement of the stabilizing strut 22 can be braked and finally stopped by the braking device 26 of the actuating unit 24 in order to prevent a collision between the boom 16 and the guying frame 18. The braking device 26 can include, for example, brake blocks, pawls and / or bolts as braking elements.

[0060] The braking device 26 can include an active friction or rigid engagement braking system which can be hydraulically actuated, electrically actuated or pneumatically actuated. If a critical state is recognized, the braking device 26 is activated and frictional or rigid engagement braking occurs. Alternatively, the stabilizing strut 22 can be actively braked by the single-wound or multi-wound cable winch 32.

[0061] Alternatively, a passive braking system can also be provided, which obtains a corresponding braking effect, for example, by means of a self-locking wedge. Such a passive braking system must also be activated in order to brake or prevent the insertion movement of the stabilizing strut 22.

[0062] As Figures 2 to 3 shown, when the boom 16 is tilted, the receiving device 17 moves not only in the horizontal direction but also in the vertical direction relative to the actuating unit 24. Therefore, in the illustrated embodiment in which the stabilizing struts 22 are configured as linear beams, these stabilizing struts must also follow the boom 16 in the vertical direction. For this purpose, the receiving device 17 can have a correspondingly configured receiving area, which allows the stabilizing struts 22 to be tilted relative to the receiving device 17. In addition, the actuating unit 24 can be actively pivoted (for example, individually pivoted) relative to the cable support 18 by means of an actuator. Figure 1 An embodiment is shown in which the actuating unit 24 is mounted on a beam 21 that extends parallel to the boom luffing axis and can be pivotally rotated as a whole based on an actuator. The actuator for pivoting the stabilizing struts 22 can be controlled and / or adjusted by means of the same control unit (for example, a crane controller) as the control / regulation cable winch 32.

[0063] In an active braking system, it is necessary to identify critical states (for example, loss of load or rolling motion of the ship). This can be done by a sensor system of the detection device of the crane 10, which can be based on different sensors, such as acceleration sensors, proximity sensors, mechanical limit switches, and / or pressure sensors. The sensors are particularly connected to a control unit that controls or activates the cable winch 32 and / or the braking device 26.

[0064] In the illustrated exemplary embodiment, the stabilizing struts 22 are actively retracted and also actively inserted until a defined boom angle. Alternatively, they can be inserted passively (especially due to the backward tilt of the boom 16), so that the traverse winch 32 does not need to be used.

[0065] Figures 6 to 7 An alternative exemplary embodiment of the crane 10 according to the invention is shown, in which the stabilizing struts 22 are not configured to be straight or linear but curved. In this case, they bend downwards or are curved. Therefore, when following the boom 16, the end 23 of the stabilizing strut 22 pointing to the receiving device 17 depicts a curve following the movement of the receiving device 17. Therefore, the stabilizing struts 22 do not need to follow or pivot in the vertical direction. Therefore, the actuating unit 24 can be rigidly connected to the cable support 18, but must be configured (for example, by means of a correspondingly curved mounting 25) such that the curved stabilizing struts 22 can be movably guided or mounted therein.

[0066] List of reference numerals:

[0067] 10 Crane

[0068] 11 Load-bearing structure

[0069] 12 Lower structure

[0070] 13 Boom head

[0071] 14 Slewing platform

[0072] 15 Cable winch / telescoping device

[0073] 16 Boom

[0074] 17 Receiving device

[0075] 18 Cable support

[0076] 19 Cable system

[0077] 20 Retraction protection device

[0078] 21 Beam

[0079] 22 Stabilizing strut

[0080] 23 End

[0081] 24 Actuating unit

[0082] 25 Mounting

[0083] 26 Braking device

[0084] 30 Cable winch system

[0085] 32 Cable winch

[0086] 34 Cable

[0087] 36 Guide pulley

[0088] 37 Guide pulley

[0089] 38 Cable winder

[0090] 39 Cable winder.

Claims

1. A crane (10), comprising: Loading structure (11); a boom (16) connected to the carrying structure (11) so as to be pivotable about a horizontal luffing axis; a guy frame (18) which is connected to the load-bearing structure (11) and via which the boom (16) is tensioned by means of a guy cable system (19) of variable length; and a rollback protection device (20) which is arranged on the guy frame (18) and is configured to prevent or brake the tilting of the boom (16) towards the guy frame (18) in a critical state of the crane (10), in particular in the event of a load shedding, wherein the rollback protection device (20) comprises at least one stabilizing strut (22) with which the boom (16) comes into contact when tilting backwards to a defined boom angle, It is characterized in that The stabilizing strut (22) is configured as a rigid element which follows the boom (16) when the defined boom angle is exceeded and can be actively inserted and / or withdrawn relative to the guying frame (18) by means of a cable winch system (30) of the rollback protection device (20).

2. The crane (10) according to claim 1, wherein the stabilizing strut (22) can be actively inserted and / or extracted by means of the cable winch system (30), and wherein the cable winch system (30) preferably comprises a cable winch (32) configured as a traversing winch, on which a cable (34) is supported, the cable being guided to and fastened at different ends of the stabilizing strut (22), in particular via a plurality of guide wheels (36).

3. The crane (10) according to claim 1, wherein the stabilizing strut (22) can be actively withdrawn via the cable winch system (30), and wherein the stabilizing strut (22) can be passively inserted, in particular by tilting the boom (16) backwards.

4. A crane (10) according to any one of the preceding claims, wherein a receiving device (17) is arranged on the boom (16), and when the defined boom angle is reached, the stabilizing strut (22) contacts the receiving device, wherein the receiving device (17) preferably has a funnel-shaped opening area, and when contacting the receiving device (17), the end of the stabilizing strut (22) facing away from the cable rack (18) is inserted into the funnel-shaped opening area.

5. A crane (10) according to any one of the preceding claims, wherein the stabilizing strut (22) is pivotably mounted on the guy frame (18) to compensate for vertical movements of a contact area of ​​the boom (16) contacted by the stabilizing strut (22) during a pivotal movement of the boom (16) beyond the defined boom angle, wherein the stabilizing strut (22) preferably has a linear shape.

6. A crane (10) according to any one of claims 1 to 4, wherein the stabilizing strut (22) has a curved shape and is configured so that a vertical movement of a contact area of ​​the boom (16) contacted by the stabilizing strut (22) during a pivotal movement of the boom (16) beyond the defined boom angle corresponds to a vertical movement of an end portion of the stabilizing strut (22) in contact with the contact area, wherein the stabilizing strut (22) is preferably non-pivotally mounted on the guy frame (18).

7. The crane (10) according to any of the preceding claims, wherein the rollback protection device (20) comprises a pressure accumulator, in particular a gas pressure accumulator, which is pressurized when the stabilizing strut (22) is inserted and assists the cable winch system (30) when the stabilizing strut (22) is withdrawn.

8. Crane (10) according to any of the preceding claims, wherein the rollback protection device (20) comprises a braking device (26) which actively or passively brakes the insertion of the stabilizing strut (22) when activated, wherein the activation is preferably carried out automatically by means of a control device when a critical state is recognized or whenever the boom (16) stops, wherein the braking device (26) preferably comprises an active friction or positive engagement braking system or a passive braking system, in particular based on a self-locking wedge.

9. The crane (10) according to any one of the preceding claims, further comprising a detection device, the detection device comprising a sensor system for detecting a critical state of the crane (10), in particular a load shedding, wherein the crane (10) preferably further comprises a control unit, the control unit receiving data from the detection device and being configured to actuate a locking device or a braking device (26) of the rollback protection device (20) when a critical state is identified.

10. A crane (10) according to any one of the preceding claims, wherein the rollback protection device (20) comprises at least one actuating unit (24), the at least one actuating unit comprising a mounting member (25) fastened to the guy frame (18) and in which the stabilizing strut (22) is movably mounted, wherein the actuating unit (24) comprises the cable winch system (30).

11. The crane (10) according to claim 10 and 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 in the mounting (25) or the cable winch system (30).

12. Crane (10) according to the preceding claims 10, 11 and developed by the features of claim 5, wherein the mounting (25) has a curved shape to movably receive a curved stabilizing strut (22).

13. The crane (10) according to any of the preceding claims, wherein the rollback protection device (20) comprises at least two stabilizing struts (22) which can preferably be inserted and / or extracted via a separate cable winch system (30).

14. A crane (10) according to any one of the preceding claims, wherein the load-bearing structure (11) comprises a slewing platform (14), which is mounted on a substructure (12) so as to be rotatable about a vertical rotation axis, and the boom (16), the guy wire rack (18) and the rollback protection device (20) are arranged on the slewing platform, wherein the crane (10) is preferably a shipboard crane, particularly preferably a heavy offshore crane, and the substructure (12) is connected to the hull of the ship.

15. A rollback protection device (20) for a crane (10) according to any one of the preceding claims.

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