Crane with bracing frame and bracing method for the crane

Abstract

To provide a crane, in particular a mobile lattice boom crane, having an upper carrier, a tiltable boom articulated to the upper carrier, and a tiltable bracing frame articulated to the upper carrier.SOLUTION: A bracing frame 18 is connectable to a boom 16 via bracing and to an upper carrier via a bracing cable 42 that is actively adjustable. A bracing cable line includes a bracing cable 42 attached to a cable winch 40 and can be wound and unwound. The bracing frame 18 is articulatedly connectable to the boom 16, and the traction element includes a variable length traction element 30 configured to apply a traction force to the bracing frame 18 in the direction of the boom 16.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a crane, in particular a mobile lattice boom crane, according to the preamble of claim 1, and to a method for moving such a crane into a braced operating position. [Background technology]

[0002] Conventionally known lattice boom cranes typically include a lower truck with a crawler chassis, a rotatable upper truck attached to the lower truck, and a lattice boom articulated to the upper truck about a horizontal axis of angular adjustment. The lattice boom typically includes a link assembly connected to the upper truck and multiple lattice sections that are bolted together to form a main boom.

[0003] The boom of a lattice boom crane is generally braced (reinforced) with an additional bracing frame (also called an A-frame, SA-frame, or erector frame) to increase the bracing angle relative to the boom and increase the leverage around the boom pivot point. The bracing frame is articulated to an upper truck that is offset relative to the boom, allowing it to pivot around a horizontal pivot axis, and is usually connected to the boom via a bracing system with multiple bracing or tension rods. The bracing frame is connected to the upper truck via a length-adjustable bracing system, and the bracing frame pivots around the pivot axis by winding or unwinding the bracing cable with a cable winch on the upper truck, thereby adjusting the boom angle up and down.

[0004] In this type of crane, the force required to raise the heavy main boom is generated by a cable winch in the bracing system. To increase the load effect of the wound bracing cable (hereinafter also referred to as "cable"), the bracing system usually has multiple deflection pulleys on the upper carriage and the bracing frame, around which the cable is wound multiple times. The force is transmitted to the tip of the boom via a tension rod on the bracing frame located between the boom and the bracing frame.

[0005] The bracing is often divided into two bracing lines, with one or more bracing frame tension rods articulated to the bracing frame and multiple boom tension rods connected to the boom. The tension rods are transported as a unit along with the components they mate with. Thus, a bracing frame tension rod is assigned to the bracing frame during transport, and a boom tension rod is assigned to each lattice section of the boom. The bracing frame tension rods are connected to the boom tension rods at connection points before the erection process. To place the crane in a braced, tilt-up operating position at the point of use, the bracing must be connected and tensioned at the connection points so that the boom can be tilted up about its tilting axis by hoisting the bracing cable of the bracing system. The required force is generated by a cable winch, as previously mentioned.

[0006] When a cable is wound onto a cable winch, it can be damaged, especially at cable crossing points between different cable layers. In multi-layer cable winches, such as those typically used in such applications, two of these crossing points exist for each cable spool, since the layers are always wound axially opposite each other around the cable drum and the cable pitch per spool must be at least one cable diameter. (One cable spool corresponds to the cable wound after one complete rotation of the cable drum.) In the case of highly tensile multi-layer windings, the crossing points are determined by the grooves in the cable drum. A cable drum with sinusoidal grooves (also known as LeBus grooves) has two parallel groove regions with no axial pitch (also known as parallel regions) and two groove regions with axial pitch (also known as pitch regions), which alternate circumferentially. In the parallel regions, the cable runs parallel to the flanged pulley (i.e., perpendicular to the drum axis), while the upper layers of the winding (the second and higher cable layers) extend directly between the two cable winches from each lower cable layer. In the pitch region, the cables rise radially upward on the cable drum and enter the next parallel groove region (or cable gap) at the crossing point.

[0007] In the parallel region, the lateral pressure from the upper cable layer is transmitted laterally from the lower cable layer to the cable winch through two line contacts.

[0008] On the other hand, in the pitch region, the load on the cable is higher because only one line of contact exists around the cable circumference and all of the lateral force is transferred to that line. As the cable moves radially up as it crosses the lower coil and leaves the groove below, less lateral force can be transferred between the coils without damage in this region (only one lateral line contact with the lower coil), so higher loads occur in this region. In particular, at the crossing points where the cable winches exactly overlap each other, the maximum load or lateral force occurs because less area is available to transfer the same lateral load (point contact at the crossing point).

[0009] Such tensioning systems typically use multi-strand wire cables made of individual steel wires, usually with plastic inserts to ensure the structural integrity of the strands. Summary of the Invention [Problem to be solved by the invention]

[0010] The main cause of damage to crossing points during operation is insufficient traction of the cable when it is being wound onto the cable winch. If the traction of the cable is too small when it is being wound onto the cable winch, the cable strands will become loose or move, and the lateral pressure stability of the cable (the resistance of the cable to deformation due to lateral loads from the upper layers) will be reduced.

[0011] The lateral pressure stability of a coiled cable is improved because the cable strands and wires are pressed together by the cable's traction force and are better supported by each other in the coiled state. If the lateral pressure stability is too low, the load on the upper layers of the cable at the crossing points will cause elastic and plastic deformation of the cable. Plastic deformation will cause permanent ovalization of the cable due to the effect of the lateral load, which will lead to breakage and subsequent scrapping. Therefore, according to manufacturer specifications, wire cables should usually be wound with a traction force of at least 10% of the nominal load (or 2.5% of the minimum breaking load) to permanently mitigate this damage.

[0012] When the main boom is raised after the bracing lines are connected, the bracing cable goes through several stages as it is wound onto the cable winch, during which it is subjected to various levels of traction. First, the cable is pulled out from the cable winch until the bracing lines can be connected at the connection points. Then, by winding the cable onto the cable winch, the bracing frame is again pivoted backwards (i.e., away from the boom). Now, since the boom is stationary and only the two connected bracing lines are under tension, only the weight of the bracing and bracing frame acts on the cable at this stage. The bracing frame and its own weight (unladen load) generate a torque around the bracing frame's pivot axis, and the traction force on the cable is large enough to exceed this torque, causing the bracing frame to pivot upwards. This means that during this tensioning stage, the cable only experiences a very small traction force (and therefore does not achieve the required traction force of at least 10% of its nominal force). At this stage, the cable is wound onto the cable winch with a weak traction force and the combined cable coil has low lateral pressure stability.

[0013] As soon as the bracing frame is tensioned, it continues to swing back, raising the boom. Initially, the boom is in a flat position, so the maximum pulling force acts on the cables here. This pulling force decreases as the boom angle increases. Therefore, with the bracing line straight, the maximum lifting force is required on the bracing tension rods to lift the boom. The steeper the boom, the less pulling force the cables will exert to hold and adjust the boom.

[0014] The coil of cable wound onto the cable winch while the boom is being raised (tilt-up phase) rests on top of the lower coil of cable that is wound with less traction during the bracing tensioning phase (tensioning phase). This lower coil of cable is pressed against the upper coil of cable that is wound with more traction at their crossing point, resulting in increased cable wear.

[0015] Against this background, the object of the present invention is to effectively reduce wear on cables of general purpose cranes. [Means for solving the problem]

[0016] According to the invention, this object is achieved by a crane having the features of claim 1 and a method having the features of claim 14. Advantageous embodiments of the invention result from the dependent claims and the following description.

[0017] Therefore, on the one hand, a crane, in particular a mobile lattice boom crane, is proposed, which has an upper carriage, an angle-adjustable (tiltable) boom articulated to the upper carriage, and an angle-adjustable (tiltable) bracing frame articulated to the upper carriage. In particular, the upper carriage is rotatably mounted on a movable lower carriage. The bracing frame can be connected to the boom via bracing. The boom and the bracing frame are preferably mounted on the upper carriage so as to be able to pivot about a horizontal axis, respectively.

[0018] The bracing frame may be articulated to the upper truck at a distance from the boom, i.e. the parallel pivot axes of the bracing frame and the boom may be arranged at a distance from each other. Alternatively, the bracing frame and the boom may be mounted on the upper truck so as to be able to pivot about a common pivot axis.

[0019] The bracing frame is connected to the upper truck via an actively adjustable bracing cable line, which has a bracing cable that can be wound and unwound by the crane's cable winch. The bracing frame can be rotated about its pivot point by adjusting the bracing cable, i.e., by winding and unwinding the cable. Because it is connected to the boom via the bracing frame, when the bracing frame swings (swings), the boom also swings (swings) (provided the bracing is under tension).

[0020] According to the present invention, the crane is equipped with a variable-length traction element, and the bracing frame is articulated to the boom via the traction element, which applies a traction force to the bracing frame in the direction of the boom. This traction force acts in addition to the torque generated by the weight of the bracing frame and bracing, and acts in the opposite direction to the lever action of the bracing frame. This additional torque generated by the variable-length traction element increases the traction force on the bracing cable line, causing the cable to be wound onto the cable winch with a greater traction force. This improves the lateral pressure stability of the cable windings in the lower (lower) coil layer on the cable winch, i.e., the cable windings wound early in the boom lifting phase during the tensioning phase. As a result, these cable coils are not subjected to the large lateral loads of the cable coils above them during the up-tilt adjustment phase, reducing cable wear and lengthening the time until the cable needs to be discarded.

[0021] In a possible embodiment, the towing element is articulated to the bracing frame and has at least one connecting means by which the towing element can be detachably connected, in particular to the boom. In the connected state, the towing element is installed between the bracing frame and the boom, in particular between the bracing frame and the lower region of the boom (e.g., the region of the boom articulation). As a result, the boom acts as a fixing point, and a sufficient weight of the boom is required. The towing element can be detachably connected to the boom so that it can be separated from the boom again without the towing element after sufficient traction has been generated, for example, when the bracing line is tensioned and the bracing frame continues to swing back due to the boom's own weight when the boom is raised.

[0022] The towing element can be permanently or detachably connected to the bracing frame. In the former case, the bracing frame can be provided with a stop that defines a parking position for the towing element while it is not connected to the boom. The towing element can be locked in the parking position. Alternatively, the towing element can be completely removed and attached to a predetermined storage position, for example, on the crane. Depending on the weight of the towing element, an auxiliary crane or an auxiliary winch may be required to move or secure the towing element to prevent it from swinging backwards.

[0023] In another possible embodiment, the towing element can be connected to a bolting point in the lower region of the boom by a cross member. The bolting point is preferably arranged on a link member articulated to the upper carriage. This allows the towing element to be attached to an existing bolting point on the boom, making it possible to retrofit the towing element of the present invention to existing cranes. The boom can be connected to the upper carriage in the region of the link member via one or more fallback cylinders, which follow the boom during operation and prevent the boom from tilting backward unexpectedly. In principle, it is also conceivable that the towing element could be connected to a bolting point between two sections of the boom via a cross member, in particular a bolting point between the link member and a lattice member bolted to it.

[0024] In another possible embodiment, the bracing comprises a first bracing line articulated to the bracing frame and a second bracing line articulated to the boom, which bracing lines are detachable from one another via connecting means, in particular articulated. The bracing lines are fixed to one another, in particular by bolts. Preferably, the first bracing line remains connected to the bracing frame, and the second bracing line remains connected to the boom. Preferably, the first and / or second bracing line comprises at least one rigid bracing or tension rod. The second bracing line, preferably formed by multiple bracing rods, is attached to each lattice section of the boom during transportation. When connected and tensioned, the bracing is particularly rigid, i.e., its length cannot be adjusted. By pivoting the bracing frame, the boom also pivots at a defined angle.

[0025] In another possible embodiment, the bracing cable is guided by at least one deflection pulley attached to the bracing frame, preferably by at least one deflection pulley attached to the upper bogie. In a preferred embodiment, the cable is guided by multiple deflection pulleys of the bracing frame and multiple deflection pulleys of the upper bogie, i.e., is passed through multiple times, and the bracing system forms a pulley block. The cable winch is configured to reel in the bracing cable, thereby pivoting (adjusting the angle) the bracing frame toward the rear of the upper bogie, and thereby adjusting the angle of the boom connected to the bracing frame via the bracing upward.

[0026] Preferably, the cable winch or its drum body has a sinusoidal groove as described above. The cable winch can be configured as a single cable winch or a double cable winch.

[0027] In a further possible embodiment, the traction element is a separate element from the bracing, the bracing frame and the boom. The traction force exerted by the traction element acts in addition to the forces generated by the weight of the aforementioned components and the bracing. This traction force generates a torque on the bracing frame, which is balanced by the corresponding high traction force cables.

[0028] The additional traction force is exerted by additional traction elements, in particular to improve the lateral pressure stability of the corresponding cable coil, and is therefore not merely a by-product of elements present in the bracing, bracing frame or other parts of the crane.

[0029] In yet another possible embodiment, the towing elements are configured to separate (uncouple) when the bracing frame pivots back, and the towing elements and boom are preferably configured so that the boom cannot be lifted while the towing elements are activated. This requires the dead weight of the boom to be sufficiently large. In this way, the boom serves as a fixed point for applying additional towing force by the variable-length towing elements. The extension (traction) can be purely passive (e.g., using springs) or actively controlled. In particular, the towing elements and boom are configured so that the amount of torque acting on the bracing frame is always less than the amount of torque acting on the boom due to the dead weight of the boom itself.

[0030] Therefore, in another possible embodiment, the traction element is passively length-adjustable and comprises spring and / or elastic elements (such as elastic tension bands), so that, in particular, the traction force generated by the traction element increases with the angle of the bracing frame relative to the boom.

[0031] In other embodiments, the traction element is actively length-adjustable and has an actuator for extending or retracting the traction element. The actuator can be, for example, a hydraulic cylinder, a cable drive, or a spindle drive. If necessary, the traction element can have passive traction elements, such as springs or tension bands, in addition to the actively actuable actuator to manipulate the dynamics of the traction element. Preferred is an embodiment in which the traction element is designed as a hydraulic cylinder connected to the hydraulic system of the crane.

[0032] In a further possible embodiment, the actuator can be controlled and / or adjusted by a control unit of the crane so that a constant, variable or changing tractive force is applied to the bracing frame over time and / or over the entire swing angle of the bracing frame. The actuator is preferably configured as a hydraulic cylinder, to which hydraulic pressure is applied so that a desired constant or variable tractive force is set over time and / or over the entire swing angle. Preferably, the cable winch is also controllable and / or adjustable by the control unit, so that the control unit can intervene in the lifting process depending on the state of the tractive element. Synchronous operation of the cable winch and the tractive element is also possible. The control unit may be the crane control unit or a separate control unit connected thereto.

[0033] In yet another possible embodiment, the crane has a measuring device connected to the control unit and capable of measuring the bracing force transmitted through the bracing, i.e., the force transmitted through the bracing. The measuring device preferably consists of at least one transducer, e.g., a load cell with one or more strain gauges, arranged on the bracing. The control unit is configured to reduce the traction force applied to the bracing frame via the traction element, particularly to zero or by switching it off, if the measured bracing force on the bracing frame exceeds a defined limit value. If the force transmitted by the bracing rises above a certain limit value, a signal is generated indicating that the bracing is under tension and the bracing frame is pivoted back, thereby raising the boom. Because the boom's own weight acts on the bracing and the cable via the bracing frame, the cable is wound onto the cable winch with a large traction force that ensures sufficient lateral pressure stability even without the traction element. This means that no additional pretensioning of the traction element is required.

[0034] In response to exceeding the defined limit value, the control unit reduces the tractive force exerted via the traction element, or preferably sets the traction force to zero or switches the traction element force to zero. This is achieved in particular by the control unit specifically controlling the actuators of the traction element. The lifting process can then either continue with the traction element decoupled but remaining connected to the bracing frame and the boom, or be interrupted and the traction element decoupled from the boom (moved to a parking position on the bracing frame or to another position on the crane, if necessary).

[0035] In yet another possible embodiment, the crane has at least one of the following sensors connected to the control unit and making its measurements available to the control unit:

[0036] The crane may be provided with at least one sensor for detecting the angular position of the bracing frame, for example by detecting the position of a cable winch and / or cable, by detecting the position of a fallback cylinder of the bracing frame, and / or by directly detecting the angular position of the bracing frame.

[0037] Alternatively or additionally, the crane may be provided with at least one sensor for detecting the angular position of the boom, for example indirectly by detecting the position of the boom's fallback cylinder and / or by detecting the angular position of the bracing frame and / or directly by detecting the angular position of the boom.

[0038] Alternatively or additionally, the crane may be provided with at least one sensor for detecting the traction force exerted by the traction element. This may be done, for example, by a load cell connected to the traction element. Monitoring the traction force of the traction element may ensure correct operation and prevent overloading of surrounding structures (especially in the event of a malfunction).

[0039] Alternatively or additionally, the crane may be provided with at least one sensor for detecting the position and / or length of the towing element. In particular, the end positions (minimum and maximum extension positions) of the towing element may be detected using suitable sensors. One or more end position sensors inform the control unit when the towing element is fully retracted and / or extended. An end position sensor for detecting and advancing the maximum extension length of the towing element can be used to detect malfunctions, for example, when the bracing rods of the bracing are not connected correctly, and protect the towing element or the crane from damage.

[0040] The control unit is configured to receive signals from the at least one sensor and, based on sensor data, to reduce, in particular to zero or switch off, the traction force applied to the bracing frame via the traction element and / or brake, in particular stop, the cable winch. In particular, the control unit can intervene in the lifting process in the event of a fault and, if necessary, stop the cable winch to prevent damage. Alternatively or additionally, the control unit can be configured to issue a corresponding warning (e.g., a visual and / or acoustic warning signal) to the operator.

[0041] The control unit is preferably configured to perform the lifting process automatically. Thus, the process of generating additional cable pretensioning is performed automatically, in particular, until, for example, a sufficiently large traction force is measured on the bracing. The traction element can then be automatically switched off, for example, by the control unit. Alternatively, the control unit can automatically stop the operation of the bracing frame so that the traction element can be decoupled from the boom and, if necessary, moved to a stop position.

[0042] In another possible embodiment, the crane comprises a lower carriage with a crawler carrier to which the upper carriage is mounted for rotation about a vertical axis of rotation. Preferably, the traction element has or is a hydraulic cylinder that is also configured as a mounting cylinder for mounting the crawler carrier. Optionally, the hydraulic cylinder can also be lifted or removed from the bracing frame. However, it is preferred that the hydraulic cylinder or the traction element remain permanently attached to the bracing frame.

[0043] As a result, the traction element performs a dual function depending on the application. For example, for assembly and disassembly of the crawler carrier, the traction element can be removed from the bracing frame and used as an assembly cylinder in a manner known per se (this is also possible if the traction element remains in the bracing frame). For raising the boom, in particular for tensioning the bracing, the traction element is attached between the bracing frame and the boom and is used to generate additional pretension and to wind the bracing cable onto the cable winch with sufficient traction. This allows fewer parts to be kept on the crane.

[0044] Generally, two or more traction elements may be provided, for example two traction elements aligned parallel to each other and mounted laterally between the bracing frame and the boom, i.e. at the same height. It is also conceivable that the traction elements may be mounted at different distances from the pivot axis of the boom and / or the pivot axis of the bracing frame.

[0045] The invention also relates to a method for moving the crane according to the invention into a bracing operation position, which is used in particular during the process of raising the crane boom, at a stage when the bracing is not yet transmitting a tractive force or is transmitting only a low tractive force, in particular when tensioning the bracing of the boom, or in the tensioning stage, where the weight of the boom is not yet acting on the bracing frame and therefore on the cable, so that the cable is wound onto the cable winch with a small cable tension.

[0046] The method according to the invention comprises the following steps, which do not necessarily have to be performed in the order given below: connecting the towing element to a boom, in particular a link member of the boom connected to the upper truck, with the boom in an unbraced prone (side-down) position; connecting a bracing to the boom, in particular connecting a first bracing line articulated to the bracing frame to a second bracing line articulated to the boom; pivoting the bracing frame away from the boom, i.e., toward the upper carriage, so that the previously connected bracing is tensioned; generating a traction force by a traction element in a direction opposite to the pivoting movement of the bracing frame in order to apply additional pretension to the bracing cable line or cable during tensioning of the bracing; Preferably, disengaging the towing element and / or decoupling the towing element from the boom; adjusting the angle of the boom by continuing to pivot the bracing frame backward; Includes.

[0047] In one possible embodiment of the method, the tensile force transmitted through the tensioning element is measured, and if the measured tensile force exceeds a defined limit value, the tensile force is reduced, in particular reduced to zero or switched off, so that no additional pretensioning of the tensile element is anymore required to guarantee a certain minimum cable tensile force on the cable when it is wound onto the cable winch.

[0048] The method according to the invention obviously offers the same advantages and properties as the crane according to the invention, and therefore will not be repeated here, and the above explanations regarding possible embodiments of the crane according to the invention therefore also apply accordingly to this method.

[0049] Further features, details and advantages of the invention emerge from the following description of exemplary embodiments, given by way of illustration. [Brief explanation of the drawings]

[0050] [Figure 1] FIG. 1 is a schematic side view of a preferred exemplary embodiment of a crane according to the present invention in a braced state without traction elements. [Figure 2] FIG. 2 is a schematic plan view of the crane according to FIG. [Figure 3] 3a-3c are schematic side views illustrating different stages of the pulling element-less boom raising process. [Figure 4] FIG. 4 is a schematic side view showing the boom raising process with integrated traction elements at different stages from those shown in FIGS. [Figure 5] FIG. 5 is a schematic side view showing the boom raising process with integrated traction elements at a different stage than in FIGS. [Figure 6] FIG. 6 is a schematic side view showing the boom raising process with integrated traction elements at a different stage than in FIGS. [Figure 7] FIG. 7 is a schematic side view showing a boom raising process with an integrated traction element at a different stage than in FIGS. 4, 5 and 6. DETAILED DESCRIPTION OF THE INVENTION

[0051] 1 and 2 show schematic side and top views of a preferred exemplary embodiment of a crane 10 according to the present invention. The exemplary embodiment described herein is a mobile lattice boom crane 10 including a lower truck 12 having a crawler chassis with two side crawler carriers 13, and an upper truck 14 mounted to the lower truck 12 for rotation about a vertical axis of rotation. A lattice boom 16 is articulated to the upper truck 14 for pivoting about a horizontal pivot axis 17. The boom 16, shown here only as a schematic line, includes, inter alia, a pivoting link assembly mounted to the upper truck 14 and multiple lattice boom sections connected together by bolted connections to form the boom 16.

[0052] The boom 16 is braced (reinforced) by bracing 20 having multiple tension rods. To increase the angle relative to the boom 16, a bracing frame 18 pivots relative to the upper truck 14 about a pivot axis 19 that is parallel to the boom pivot axis 17. The bracing frame 18 is connected to the boom 16 via the rigid bracing 20 (in a tensioned state), and the angle of the boom 16 can be adjusted up and down by pivoting the bracing frame 18.

[0053] The bracing 20 is divided into two parts: a first bracing line 21, which is articulated to the upper region of the bracing frame 18, and a second bracing line 22, which is articulated to the boom 16, in particular to the tip of the boom 16. For transportation, the crane 10 is disassembled into several parts, which are transported separately. For this purpose, the first bracing line 21 is assigned to the bracing frame 18, and the second bracing line 22 consists of several tension rods assigned to each lattice section of the boom 16 and is transported together with them in particular. The first bracing line 21 can also consist of several tension rods. As the plan view in FIG. 2 shows, the bracing 20 has two parallel bracing lines, each consisting of a first and second bracing line 21, 22.

[0054] 3a-3c show various positions of the crane 10 during boom assembly, i.e., during bracing and raising of the boom 16. The boom 16 is moved and thus raised by pivoting the bracing frame 18, which is connected to the upper truck 14 via an adjustable bracing cable line 24. The bracing cable line 24 has a tension cable 42 (abbreviated as "cable") attached to a cable winch 40 or cable drum located on the upper truck 14 for winding and unwinding. The cable 42 is guided across multiple deflection pulleys 28 rotatably mounted on the bracing frame 18 and multiple deflection pulleys 27 rotatably mounted at the rear of the upper structure, so that the bracing cable 24 forms a pulley block. In FIG. 2, the cable winch 40 is shown as a double cable winch, with both ends of the cable 42 connected to the rotatable drum body of the cable winch 40. However, it is also possible to use a single cable winch in which only one end of the cable 42 is connected to the cable winch 40 .

[0055] The cable winch 40 has a cylindrical drum body and a flange disc laterally disposed on the end face of the drum body. The flange disc prevents the cable 42 wound around the drum body from slipping off during winding (multi-layer winding) and forces it against the upper winding layer. The drum body is rotatable about an axis of rotation to wind or unwind the cable 42. In particular, the drum body of the cable winch 40 is provided with the sinusoidal or LeBus grooves described above, in which the geometric orientation of the cable coil is determined in the first cable layer and is maintained in all subsequent cable layers, thereby creating the most compact and repeatable winding pattern.

[0056] The force required to raise the heavy boom 16 is generated solely by the cable winch 40. The pulling force of the cable 42 is transmitted to the boom 16 via the bracing 20.

[0057] To assemble the bracing 20, the boom 16 is placed on the ground (or on a trolley), and the bracing lines 21, 22 are gathered together and then articulated together by means of the connecting means 23, in particular bolts. For this, as shown in FIG. 3a, the bracing frame 18 is pivoted forward toward the boom 16, with the first bracing line 21 hanging vertically downward due to gravity. The bracing frame 18 is then angled (tilted) until the connecting means 23 of the two bracing lines 21, 22 can be connected together. The bracing frame 18 is then pivoted back toward the upper carriage 14, and the bracing 20 is slowly tensioned until it reaches the position shown in FIG. 3b. Until then, the bracing 20 is not tensioned, so pivoting the bracing frame 18 back will not lift the boom 16. This stage can also be called the tensioning stage. Once the bracing 20 is tensioned (thus causing the two bracing lines 21, 22 to run substantially parallel (see Figure 3b), it should be noted that even when tensioned, a bracing line always sags slightly due to its own weight), further pivoting of the bracing frame 18 backward causes the boom 16 to lift off the ground or its support and tilt upward (see Figure 3c).

[0058] 3a-3c show the corresponding winding states of the cable 42 on the cable winch 40 for each crane configuration, and in each figure the cable winch 40 is shown as a longitudinal cross section along the drum axis, i.e., as a cross section through the parallel groove areas. The cable coil is shown differently depending on the tractive forces acting at various stages during winding.

[0059] In the state shown in Figure 3a, the cable 42 is almost fully unwound, showing the safety coil 50, which is not unwound, i.e., not in use. The light grey coil 51 represents a cable coil wound with a small traction force. This is because, in the state shown in Figure 3a, only the weight of the bracing frame 18 and the first bracing line 21 (shown by the force arrow F1) acts on the cable 42. To achieve the state shown in Figure 3a, the cable 42 is unwound from the cable winch 40 until the connecting means 23 can be connected. The cable 42 is then reeled in, causing the bracing frame 18 to swing back again.

[0060] Even after the bracing lines 21, 22 are connected during the tensioning phase, only the small weight load of the bracing 20 and bracing frame 18 acts, generating a small torque about the pivot axis 19 of the bracing frame 18. The traction force of the cable 42 is large enough to overcome this torque and cause the bracing frame 18 to pivot upward. Therefore, a cable coil 51 wound in this manner has only little lateral pressure stability.

[0061] From the moment the bracing 20 is fully tensioned (see Figure 3b), a maximum lifting force (shown by arrow F2) is required to lift the boom 16 off the ground. The steeper the boom 16, the less pulling force the cable 42 must exert to hold and adjust the boom 16 (see arrow F3 in Figure 3c).

[0062] The dashed lines in Figures 3b and 3c show the position of the bracing frame 18 in Figure 3a, with angular regions 61, 62, 63 assigned to each cable coil 51, 52, 53. In angular region 61 (i.e., during the tensioning phase), the cable coil 51 is wound with a small traction force. The largest traction force is exerted in angular region 62 (the first section of the tilting phase). The corresponding cable coil 52 rests on the weakly wound cable coil 51. In angular region 63 (later part of the upward tilting phase), the boom 16 is in a steeper position, so a very small traction force is exerted again, which corresponds to the cable coil 53 shown in light grey.

[0063] The object of the present invention is to increase the traction force of the cable coil 51 that is wound during tensioning of the bracing 20 to form the bottom winding layer of the cable drum 40 in order to increase lateral pressure stability.

[0064] For this purpose, according to the invention, a variable-length traction element 30 is provided, which is mounted between the bracing frame 18 and the boom 16 and which exerts an additional traction or pretensioning force on the cable 42 during the tensioning phase. As a result, when tensioning the bracing 20, the cable is wound onto the cable winch 40 with a greater traction force than if only the weight of the working parts acted on the cable 42. This improves the lateral pressure stability of these cable coils 51 and thus effectively reduces cable wear.

[0065] Figures 4-7 are side views of the crane 10 according to the present invention with the traction element 30 in various positions during bracing and raising of the boom 16. It should also be noted at this point that what is depicted in Figures 1-3c may be considered a schematic representation of the crane 10 according to the present invention without the traction element 30 attached.

[0066] In the exemplary embodiment shown, the traction element 30 is configured as an actively adjustable hydraulic cylinder 31, although other actuators may alternatively be used, for example electric actuators such as spindle drives or cable drives, or passive elements such as springs. The hydraulic cylinder 31 is connected to the hydraulic system of the crane 10 and can be controlled by a control unit (not shown in detail), in particular a crane control system, to target and generate the desired traction force.

[0067] Depending on the desired control, the traction element 30 can exert a constant or variable traction force on the bracing frame 18. This results in a torque on the bracing frame 18 that opposes the rearward pivoting movement of the bracing frame 18, i.e., away from the boom 16, and is compensated by a corresponding larger traction force from the cable 42.

[0068] As shown in Figure 4, the towing element 30 is located between the bracing frame 18 and the boom 16 and is articulated thereto. At its other end, the towing element 30 has a connection means 32 for articulated attachment to a suitable connection point on the boom 16. This connection point may be an existing bolting point between a boom linkage and the subsequent lattice section, or another connection point within or on the linkage of the lattice boom 16. Optionally, the towing element 30 may be attached to the boom 16 via a cross member so that it can be retrofitted to an already delivered crane 10.

[0069] To brace the boom 16, the boom 16 is first placed on the ground or a supporting device such as a trolley. The bracing frame 18 is then pivoted forward toward the boom 16. The traction element 30, pivotably attached to the bracing frame 18, moves with it, pivoting away from the bracing frame 18 by gravity once it has passed a 90° angle, aligning itself substantially vertically. The bracing frame 18 pivots until the connecting means 32 of the traction element 30 can connect to the connecting point on the boom 16 (see FIG. 4). The bracing frame 18 pivots toward the boom 16 by withdrawing the cable 42, while the traction element 30 shortens (i.e., the hydraulic cylinder is retracted) until it reaches its minimum length or end position. The cable winch 42 and the traction element 30 are thus controlled synchronously by the control unit in a targeted manner. This ensures that the traction element 30 is not under pressure. In this position, a sufficient number of cable coils are withdrawn from the cable winch 40, allowing it to be withdrawn with a greater traction force (see the right-hand view of FIG. 4, which shows a longitudinal section through the cable winch 40 in this position). Any cable coils deflected by the deflection pulleys 28, 29 are withdrawn during operation. Cable winches wound with too little pretension (remaining coils 51 in FIG. 4) are of no importance, as they do not reach the deflection pulleys 28, 29.

[0070] To tension the interconnected bracing lines 21, 22 in an articulated manner, the bracing frame 18 then pivots back toward the upper truck by winding the cable 42 onto the cable winch 40 against the additional traction force (constant or variable) generated by the traction element 30 (see FIG. 5). The traction element 30 is then pulled away. The additional traction force of the traction element 30 (actively generated in this exemplary embodiment) increases the traction force on the cable 42, thereby increasing the cable's lateral pressure stability over its entire range (see light gray cable coil 51' in FIG. 5). The boom 16 is heavy enough to prevent the upward force from the traction element 30 from lifting it off its support, acting as an anchor point.

[0071] The process of generating additional cable pretensioning by the traction element 30 is preferably switched off by the control unit in a predetermined manner as soon as the traction force on the cable 42 due to the load transmitted by the tensioning device 20 is sufficiently large. This is the case when the bracing lines 21, 22 are tensioned and the weight of the boom 16 acts on the cable 42 via the bracing 20 (see FIG. 6). The corresponding cable coil, shown in dark gray in FIG. 6 and designated by reference number 52, is wound onto the cable winch 40 with sufficient traction force even without the additional pretensioning of the traction element 30. The load transmitted via the bracing 20 is preferably recorded using a load transducer. If the measured load exceeds a certain limit value, which is stored in the control unit and can be changed as desired, the traction element 30 is deactivated or switched off by the control unit.

[0072] In principle, the traction element 30 can be configured in such a way that it maintains the connection between the bracing frame 18 and the boom 16 even when the power is switched off. However, it is preferable to disconnect the mechanical connection with the boom 16 after the traction element 30 has been switched off. The traction element 30 can then be swung backwards, for example to a parking position for the bracing frame 18, which is defined by the stop position. To prevent uncontrolled backward swinging, the traction element 30 can be secured, for example by an auxiliary winch or an auxiliary crane. Alternatively, the traction element can be detached from the bracing frame 18 and stored in a specific storage position on the crane 10, as required.

[0073] When the bracing 20 is tensioned, the boom 16 lifts from its support and rises as the cable 42 continues to be wound up (see FIG. 7, which also shows possible parking positions for the traction elements 30 of the bracing frame 18). As the boom 16 rises, a very large traction force is generated on the cable 42 (see the dark grey cable coils 52 in FIG. 7). The associated cable coils 52 exert a side load on the cable coils 51' that were previously wound when the traction elements 30 were activated. As the cable coils are wound by the traction elements 30 under increased traction force, the cable has greater side load stability. As a result, these cable winches 51' are no longer damaged or experience less wear.

[0074] The bracing and erection processes described above are preferably at least partially, and optionally fully, automated. This can be done, for example, as follows: After connecting the traction element 30 to the boom 16, the crane operator initiates the cable pulley tensioning process in the crane control system. This process is then executed automatically. For this purpose, the traction element 30 is equipped with sensors that detect its end positions (minimum and maximum lengths). The angular positions of the bracing frame 18 and the boom 16 are also detected. The measured values ​​are made available to the crane control system. The minimum length end position sensor signals the control unit when the traction element 30 is fully retracted. The maximum length end position sensor is used to detect faults (e.g., incorrect connection of the tension rods of the bracing 20) and protect the system from damage. The load on the traction element 30 is also monitored. This ensures correct operation and prevents overloading of the surrounding structure (especially in the event of a fault). [Explanation of symbols]

[0075] 10 Crane 11 Rotation axis 12 Lower bogie 13 Crawler carrier 14 Upper bogie 16. Boom 17 Swivel axis 18 Bracing frame 19 Swivel axis 20 Bracing 21 First Bracing Line 22 Second Bracing Line 23 Connection means 24 bracing cable wire 28 Deflection pulley 29 Deflection pulley 30 Traction elements 31 Actuator (hydraulic cylinder) 32 Connection means 40 Cable Winch 42 Bracing Cable / Cable 50 Safety coil (not drawn out) 51 Cable coil (not unwound / tensioning stage without tensioning elements) 51' cable coil (tensioning stage with tensioning elements) 52 Cable coil (upward angle adjustment stage) 61 Angular area 62 angular area 63 Angular area

Claims

1. A crane (10) having an upper carriage (14), a tiltable boom (16) articulated to the upper carriage (14), and an angle-adjustable bracing frame (18) articulated to the upper carriage (14), the bracing frame (18) is connected to the boom (16) via bracing (20), the bracing frame (18) is connected to the upper carriage (14) via an actively adjustable bracing cable line (24), the bracing cable line (24) having a bracing cable (42) attached to a cable winch (40) so as to be capable of being wound and unwound by the cable winch (40); a variable-length traction element (30) capable of connecting the bracing frame (18) to the boom (16) in an articulated manner and configured to exert a traction force on the bracing frame (18) in the direction of the boom (16); A crane (10) comprising a lower carriage (12) having a crawler carrier (13), the upper carriage (14) being rotatably mounted on the lower carriage (12) about a vertical axis of rotation, the traction element (30) having a hydraulic cylinder (31) configured as a mounting cylinder for mounting the crawler carrier (13) or being the hydraulic cylinder (31).

2. The crane (10) of claim 1, The towing element (30) is articulated to the bracing frame (18) and has at least one connecting means (32) by which the towing element (30) can be detachably connected and articulated to the boom (16).

3. The crane (10) of claim 1, The crane (10) comprises a cross member connectable to a bolting point in the lower region of the boom (16), the bolting point being arranged on a link member articulated to the upper carriage (14).

4. The crane (10) of claim 1, The bracing (20) comprises a first bracing line (21) connected in an articulated manner to the bracing frame (18) and a second bracing line (22) connected in an articulated manner to the boom (16), and these bracing lines (21, 22) are detachable from each other via a connecting means (23), and the first and / or second bracing line (21, 22) has at least one bracing rod.

5. The crane (10) of claim 1, the bracing cable (42) is guided to at least one deflection pulley (28) attached to the bracing frame (18) and to at least one deflection pulley (29) attached to the upper bogie (14); The cable winch (40) is configured to rotate the bracing frame (18) toward the rear of the upper truck by winding up the bracing cable (42), thereby tilting the boom (16) connected to the bracing frame (18) via the bracing (20), and the cable winch (40) has a sinusoidal groove and is configured as a single cable winch or a double cable winch.

6. The crane (10) of claim 1, A crane (10) in which the towing element (30) is a separate element from the bracing (20), the bracing frame (18), and the boom (16).

7. The crane (10) of claim 1, The towing element (30) is configured to be separated when the bracing frame (18) swings away from the boom (16), and the towing element (30) and the boom (16) are configured so that the boom (16) is not lifted while the towing element (30) acts on the bracing frame (18).

8. The crane (10) of claim 1, A crane (10) in which the traction element (30) is passively length-adjustable and has spring and / or elastic elements.

9. The crane (10) of claim 1, The crane (10) has a traction element (30) that is actively length-adjustable and has an actuator (31) for extending and contracting the traction element (30), the actuator (31) being a hydraulic cylinder, a cable drive, or a spindle drive.

10. A crane (10) according to claim 9, The actuator (31) can be controlled and / or adjusted by a control unit of the crane (10), so that a constant or varying tractive force is applied to the bracing frame (18) over time and / or over the entire swing angle of the bracing frame (18), and the cable winch (40) can also be controlled and / or adjusted by the control unit of the crane (10).

11. A crane (10) according to claim 10, The crane (10) has a measuring device connected to the control unit and capable of measuring the bracing force transmitted through the tensioning device (20), the control unit being configured to reduce the traction force applied to the bracing frame (18) through the traction element (30) when the measured bracing force exceeds a defined limit value, and the measuring device has at least one measurement sensor arranged on the bracing (20).

12. A crane (10) according to claim 10, As a sensor connected to the control unit, a sensor for detecting the angular position of the bracing frame (18); a sensor for detecting the angular position of the boom (16); a sensor for detecting the traction force exerted by said traction element (30); a sensor for detecting the position and / or length of said traction element (30); and The crane (10) is configured such that the control unit reduces the traction force applied to the bracing frame (18) via the traction element (30) and / or brakes and stops the cable winch (40) based on a signal from at least one sensor.

13. A method for moving a crane (10) having an upper carriage (14), a tiltable boom (16) articulated to said upper carriage (14), and an angle-adjustable bracing frame (18) articulated to said upper carriage (14) to a bracing operating position, comprising: The bracing frame (18) is connected to the boom (16) via bracing (20), and the bracing frame (18) is connected to the upper truck (14) via an actively adjustable bracing cable line (24), the bracing cable line (24) having a bracing cable (42) attached to a cable winch (40) so as to be reelable and unreelable by the cable winch (40); a variable-length traction element (30) capable of connecting the bracing frame (18) to the boom (16) in an articulated manner and configured to exert a traction force on the bracing frame (18) in the direction of the boom (16); connecting the towing element (30) to a link member articulated to the boom (16), the boom (16) being in an unbraced prone position; a step of connecting the bracing (20), in which a first bracing line (21) articulated to the bracing frame (18) is connected to a second bracing line (22) articulated to the boom (16); pivoting the bracing frame (18) away from the boom (16) so that the bracing (20) is tensioned; generating a traction force by the traction element (30) in a direction opposite to the pivoting movement of the bracing frame (18) to apply additional pretension to the bracing cable line (24) during tensioning of the bracing (20); decoupling the towing element (30) from the boom (16); tilting the boom (16) by continuing to pivot the bracing frame (18); A method having the following.

14. A method for moving a crane (10) having an upper carriage (14), a tiltable boom (16) articulated to said upper carriage (14), and an angle-adjustable bracing frame (18) articulated to said upper carriage (14) to a bracing operating position, comprising: the bracing frame (18) is connected to the boom (16) via bracing (20), the bracing frame (18) is connected to the upper carriage (14) via an actively adjustable bracing cable line (24), the bracing cable line (24) having a bracing cable (42) attached to a cable winch (40) so as to be capable of being wound and unwound by the cable winch (40); a variable-length traction element (30) capable of connecting the bracing frame (18) to the boom (16) in an articulated manner and configured to exert a traction force on the bracing frame (18) in the direction of the boom (16); connecting the towing element (30) to a link member articulated to the boom (16), the boom (16) being in an unbraced prone position; a step of connecting the bracing (20), in which a first bracing line (21) articulated to the bracing frame (18) is connected to a second bracing line (22) articulated to the boom (16); pivoting the bracing frame (18) away from the boom (16) so that the bracing (20) is tensioned; generating a traction force by the traction element (30) in a direction opposite to the pivoting movement of the bracing frame (18) to apply additional pretension to the bracing cable line (24) during tensioning of the bracing (20); disengaging the towing element (30) and decoupling the towing element (30) from the boom (16); tilting the boom (16) by continuing to pivot the bracing frame (18); A method having the following.

15. 15. The method of claim 13 or 14, The bracing force transmitted through the bracing (20) is measured, and the traction force is reduced when the measured bracing force exceeds a defined limit value.

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