EP4091980A1 - Lifting system and method for a crane - Google Patents

Abstract

The invention relates to a hoisting system for a crane, in particular a mobile or crawler crane, for generating a hoist rope pretension during a hoist of a suspension element of the crane, comprising a divisible pretensioning hook block and an auxiliary rope connected thereto, which can be wound up and unwound on an auxiliary winch arranged or mountable on the crane is stored and guided over a deflection device which is arranged or can be mounted on a boom of the crane. According to the invention, the pretensioning hook block comprises two hook block parts that can be releasably locked together and are connected to one another via the auxiliary rope, of which an upper hook block part has a fastening means for fastening to the suspension means of the crane and a lower hook block part has a receiving means for fastening a weight. The invention also relates to a pretensioning hook block of the lifting system according to the invention and a crane with such a device. Furthermore, the invention relates to a method for lifting a carrying element of a crane using the lifting system according to the invention.

Description

The present invention relates to a hoisting system for a crane, in particular a mobile or crawler crane, for generating a hoist rope pretension during a hoist of a suspension element of the crane, a crane with such a hoisting system, a pretensioning hook block and a method for lifting a suspension element of a crane using a such lifting system.

With most cranes, loads are picked up and lifted using load-bearing means (usually hook blocks with load hooks) carrying hoist ropes, which are guided on a crane boom via deflection means and stored on hoist winches so that they can be wound up and unwound. The hoisting ropes are usually stored in multiple layers on the hoisting winches. In order to avoid "cutting in" during the spooling process, the hoisting ropes on the hoisting winches must be wound as tightly as possible in the lower layers. During the normal hoisting process, the hoisting rope is largely unwound when the load is picked up on the ground and is wound up on the hoisting winch during the hoisting process. The load generates the necessary pre-tension on the coiled-up hoist rope so that it is coiled up sufficiently tightly on the hoist winch.

If the crane is used to carry out dismantling processes (e.g. chimney dismantling or wind turbine dismantling), loads often have to be picked up at a great height and set down on the ground. For this purpose, the bottom hook block becomes "empty" wound up, ie lifted without a load, the load then picked up at the height and then set down on the ground.

This means that when the bottom hook block is lifted, the lower layers of the hoisting rope are only pretensioned using the hook block's own weight when it is spooled onto the hoist winch, and the high load is only absorbed on the top layer of the winch. The risk of rope cutting and thus damage to the rope through to ropes that are ready to be discarded is therefore very high in such dismantling processes.

In order to circumvent this problem, the hook block weight is currently increased in the simplest case, for example by using a larger load hook and/or with additional weights. In addition, if possible, the reeving of the bottom hook block can be selected to be as small as possible and parallel operation with two winches can be avoided. These measures reduce the length of the hoist rope unwound from a winch drum and at the same time increase the pretension on the hoist rope due to the lower reeving with the same weight of the bottom hook block. However, using a heavier bottom hook block results in a reduction in the maximum possible payload of the crane.

Furthermore, the possibility is known from the prior art of hoisting an additional weight together with the otherwise empty load hook and setting it down on the structure or the like. This has the same effect as increasing the weight of the bottom hook block, but has the advantage that the additional weight does not remain on the bottom hook block when the load is actually lifted from height to ground, and the available lifting capacity is therefore not reduced. The disadvantage here is that in most cases it is not possible to set down or store such an additional weight on the structure or similar at the load bearing point.

Another possible solution is from the DE 20 2013 006 584 U1 a pretensioning winch is known, which pulls on the load hook weighted with a ballast weight on the ground and thus generates an additional pretension on the hoist rope. However, this requires the provision of another support vehicle at the construction site.

The present invention is therefore based on the object of ensuring good winding quality when winding the hoist rope onto the hoist winch of a crane, without the need for additional auxiliary vehicles or the need to place a weight at a great height.

According to the invention, this object is achieved by a lifting system having the features of claim 1, a pretensioning hook block having the features of claim 11 and a method according to claim 12. Advantageous embodiments of the invention result from the dependent claims and the following description.

Accordingly, a hoisting system for a crane, in particular a mobile or crawler crane, is proposed for generating a hoisting cable pretension during a hoisting of a suspension element of the crane. The lifting system according to the invention comprises a divisible pretensioning hook block and an associated auxiliary rope, which is mounted so that it can be wound up and unwound on an auxiliary winch arranged or mountable on the crane and guided over a deflection device arranged or mountable on a boom of the crane. By winding and unwinding the auxiliary rope, the pretensioning hook block can be raised and lowered relative to the deflection device. According to the invention, the pretensioning hook block comprises two hook block parts that can be releasably locked or fixed with one another and are connected to one another via the auxiliary rope, of which an upper hook block part has a fastening means for fastening to the suspension means of the crane and a lower hook block part has a receiving means for fastening or receiving a weight.

If the upper hook block part is connected to the suspension means, it can be raised and lowered together with it. The lower hook block part is connected to a weight in order to use this additional weight to exert a pretensioning force on the hoist rope of the crane, which carries the suspension element, and thereby ensure good winding quality on the corresponding hoist winch.

Due to the fact that the pretensioning hook block can be divided, the two hook block parts can be moved independently of one another and the weight connected to the lower hook block part does not have to be lifted together with the suspension element when it is lifted. Skillful control or regulation of the auxiliary winch allows the position or movement of the weight connected to the lower hook block part to be controlled precisely and safely, for example via a crane control system for the crane.

Because the two hook block parts are connected to one another via the auxiliary rope, they can be moved apart or brought together by appropriate control of the auxiliary winch. For example, after the suspension element has been raised to a desired height, the weight connected to the lower hook block part can be set down again on the ground and released from the lower hook block part by appropriate control of the auxiliary winch, so that the latter can then be raised again by winding up the auxiliary rope and connected to the upper hook block part can be merged and locked if necessary. Since the prestressing hook block "hangs" on the separate auxiliary rope, the prestressing hook block can be detached from the suspension means in the raised position, so that the latter is available for receiving a part that is to be dismantled.

The lifting system according to the invention thus makes it possible, by using an additional weight when lifting the "empty" suspension means, to exert a pretensioning force on the lifting cable and thus to guarantee good winding quality, with no external auxiliary devices or vehicles having to be used apart from the weight. The weight that generates the pretensioning force does not have to be placed in an elevated position, but can remain in the area of the floor. This provides a flexible and easy-to-use system that can be used in dismantling operations to ensure good hoist rope winding quality and includes few additional parts to carry.

With the solution described, the load can be kept close to the ground. This is an improvement in security aspects. In the area under one A suspended load is always a hazard and the area should be avoided by people.

Since many cranes, for example lattice boom cranes (i.e. cranes with lattice jibs), already have an auxiliary winch with an auxiliary rope and a mast nose that can be mounted on the jib tip as part of the standard equipment, in such a case only the pretensioning hook block according to the invention has to be connected to the auxiliary rope. This does not take up much space and can easily be carried on the crane. Thus, when used on a telescopic crane, no complicated conversion of the crane is required in order to use the lifting system according to the invention, which would require a separate static consideration. The lifting system according to the invention can easily be retrofitted to existing cranes or attached for individual applications and then dismantled again.

When it is mentioned here that the auxiliary winch or hoist winch is wound up or unwound or wound up or unwound, this is intended to express in abbreviated form that the corresponding auxiliary rope or hoist rope is wound up or unwound onto or from the winch or .wound up or unwound.

The feature that the upper and lower hook block parts are connected to one another via the auxiliary rope is to be interpreted broadly and to be understood in such a way that the auxiliary rope runs between these two hook block parts. The two hook block parts are movable in particular with respect to one another.

In one possible embodiment it is provided that at least a first deflection pulley is arranged on the upper hook block part and a second deflection pulley is arranged on the lower hook block part, over which the auxiliary rope is guided. This means that the pretensioning hook block has at least two reeving points for the auxiliary rope.

The reeving of the auxiliary rope can be designed in such a way that its end is attached to the lower part of the hook block. Together with a deflection pulley provided on the deflection device, this results in a total of three strands in the simplest case, in which the lower and upper hook block part each have exactly one deflection pulley, with the first strand of the auxiliary rope between the deflection device and the lower hook block part, the second strand between the lower hook block part and upper hook block part and the third strand runs from the upper hook block part for attachment to the lower hook block part. The mass of the attached weight is distributed proportionally to the different strands of the pulley. In the case of three strands, two strands contribute to increasing the pretension, so that approx. 2/3 of the weight hangs on the lifting gear and tensions the hoist rope, which is wound onto the hoist winch.

Of course, other configurations of the block and tackle are also conceivable here, for example with more than one deflection pulley per upper and/or lower hook block part.

In a further possible embodiment it is provided that the pretensioning hook block has at least one deflection pulley for guiding the auxiliary rope laterally past the suspension means, which is preferably arranged on the upper hook block part. In particular, this additional deflection pulley is not used for reeving the auxiliary rope to distribute the weight of the additional weight, but only for guiding the auxiliary rope past. Alternatively, however, it is also conceivable that one of the deflection rollers of the block and tackle is used at the same time for guiding past.

In a further possible embodiment it is provided that the pretensioning hook block comprises a guide mechanism, by means of which the lower and upper hook block parts can be brought into a defined locking position when they are brought together. The guide mechanism can be used for the precise alignment of the upper and lower hook block parts and/or enable easier insertion of the two hook block parts into one another.

Preferably, the guide mechanism includes one or more guide rails. Alternatively or additionally, the guiding mechanism may comprise a tongue and groove mechanism, the groove being able to be attached to the lower hook block and the tongue to be attached to the upper hook block. The reverse case is also possible. The guide mechanism is preferably designed in such a way that the hook block parts are brought together automatically in a raised position, without manual assistance having to be provided.

In a further possible embodiment it is provided that the lower and upper hook block parts have connecting means for releasable locking with one another. The connecting means preferably enable the lower and upper hook block parts to be bolted together by means of one or more bolts.

In a further possible embodiment it is provided that the lower and upper hook block parts can be locked by means of an actuatable locking mechanism, the locking mechanism preferably being able to be actuated actively or passively when or after the upper and lower hook block parts are brought together. Active actuation can take place, for example, by means of electrically or hydraulically controlled locking bolts. However, passive actuation of the locking mechanism is preferred, triggered in particular when the upper and lower hook block parts are brought together. As a result, the pretensioning hook block can have a simple design.

In a further possible embodiment it is provided that the locking mechanism is designed to lock automatically when the lower and upper hook block parts are brought together and preferably comprises a spring element and/or a snap mechanism. The snap mechanism can, for example, comprise a pivotable hook element, which is arranged on the upper or lower hook block part in such a way that when the hook block part is brought together, the respective other hook block part pivots the hook element and the latter moves into a locking position of the upper and lower by a spring mechanism Hook element snaps back and grips a bolt on the other hook block part in such a way that the two hook block parts are locked together. Instead of the hook element and bolt, other elements can be used, for example a sliding bolt.

Due to the automatic locking when the hook block parts are brought together, there is no need for manual bolting when bringing them together, which considerably simplifies the lifting process. It is also conceivable for manual bolting to take place in addition to the locking mechanism that can be actuated automatically.

In a further possible embodiment, a hoisting winch is also provided, on which a hoisting rope connected to the suspension means can be wound up and unwound, the hoisting winch and the auxiliary winch preferably being actuatable independently of one another and thus the suspension means and the pretensioning hook block being able to be lifted independently of one another. The hoist winch and the auxiliary winch can preferably be actuated by a crane control.

In a further possible embodiment, a crane controller is also provided, which is set up to control the hoist winch and the auxiliary winch in a synchronized manner in such a way that during a lift of the suspension element, by winding up the hoist winch and simultaneously unwinding the auxiliary winch, a weight attached to the unlocked pretensioning hook block is at a certain height held floating above the ground. The height and/or orientation of the weight can be detected by appropriate sensors and the measured values can be included in the control.

The entire pretensioning process can thus advantageously be carried out and monitored by the crane controller. The pretensioning process can therefore correspond to regular crane operation, for example monitored two-hook operation, with a hook on the suspension element as the main hoist, actuated by the hoist winch, and a hook on the leader hook block actuated by the auxiliary winch with a common load.

The present invention also relates to a crane, in particular a mobile or crawler crane, which includes the lifting system according to the invention. Both the hoist winch and the auxiliary winch are preferably attached to an upper carriage of the crane and can be actuated independently via a crane control.

The suspension means can be a hook block of the crane. Alternatively or additionally, the deflection device can be a mast nose or folding jib that can be mounted on the boom tip, which preferably has at least one deflection pulley over which the auxiliary rope is guided.

The present invention further relates to a pretensioning hook block of the lifting system according to the invention. The pretensioning hook block includes an auxiliary rope fastening means for fastening the auxiliary rope of the lifting system, which is preferably arranged on the lower hook block part. In order to attach the auxiliary rope to the prestressing hook block, it is reeved into the two hook block parts and connected to the auxiliary rope attachment means. This obviously results in the same advantages and properties as for the lifting system according to the invention, which is why a repeated description is dispensed with at this point. The above statements with regard to the possible configurations of the pretensioning hook block therefore apply accordingly.

• Befestigen der Vorspannhakenflasche am Tragmittel,
• Entriegeln der oberen und unteren Hakenflaschenteile, beispielsweise durch Entfernen eines oder mehrerer Bolzen,
• Befestigen eines Gewichts am unteren Hakenflaschenteil,
• Heben des Tragmittels, insbesondere durch Aufspulen eines mit dem Tragmittel verbundenen Hubseils auf eine Hubwinde, wodurch sich die unteren und oberen Hakenflaschenteile voneinander entfernen (d.h. das obere Hakenflaschenteil wird zusammen mit dem Tragmittel nach oben gezogen, während das untere Hakenflaschenteil am Gewicht verbleibt), und
• Absetzen des Gewichts auf dem Boden nach erfolgtem Hub des Tragmittels durch Abspulen der Hilfswinde, während sich das Tragmittel in seiner gehobenen Position befindet, und Lösen des unteren Hakenflaschenteils vom Gewicht.

The present invention further relates to a method for lifting a carrying element of a crane using the lifting system according to the invention with the following steps:

• Fastening the pretensioning hook block to the suspension equipment,
• unlocking the upper and lower hook block parts, for example by removing one or more bolts,
• attaching a weight to the lower hook block part,
• Lifting of the suspension means, in particular by winding a hoist rope connected to the suspension means onto a hoist winch, as a result of which the lower and upper hook block parts move away from each other (i.e. the upper hook block part is pulled up together with the suspension means, while the lower hook block part remains attached to the weight), and
• Depositing the weight on the ground after the suspension means has been raised by unwinding the auxiliary winch while the suspension means is in its raised position and releasing the lower hook block portion from the weight.

This obviously results in the same advantages and properties as for the lifting system according to the invention, which is why a repeated description is dispensed with at this point.

The first three steps can be performed in any order.

In one possible embodiment of the method, it is provided that after the weight has been set down and released, the lower hook block part is lifted by winding up the auxiliary winch and brought together with the upper hook block part, so that the hook block parts can be locked together, with the locked pretensioning hook block then preferably being released from the suspension element and set down on the ground by unwinding the auxiliary winch. The suspension element can now be connected to a part to be dismantled at a great height, for example, and the part can be lowered to the ground. The procedure can then be repeated so that there is sufficient pre-tensioning force for the hoist rope with each lift of the "empty" suspension element.

Accessibility for detaching the pretensioning hook block from the suspension element can be taken for granted, since the load to be dismantled must be attached to the suspension element in the next step.

In a further possible embodiment of the method it is provided that for the lifting of the support means the hoisting winch and the auxiliary winch are synchronously or are controlled synchronously, in particular via a crane control of the crane, that the weight is kept at a certain height, in particular floating above the ground, by winding up the hoist winch and simultaneously unwinding the auxiliary winch.

In a further possible embodiment of the method, it is provided that the lifting of the support means takes place in a two-hook operation monitored by the crane controller, with the hoist and auxiliary winches preferably being automatically regulated by the crane controller in such a way that the weight is in a defined height above the ground and/or in a certain position.

A use of the system according to the invention, as presented above, results from claim 16.

Figur 1:

eine schematische Seitenansicht der erfindungsgemäßen Vorspannhakenflasche in einem verriegelten und an einem Lasthaken eines Krans aufgehängten Zustand gemäß einem Ausführungsbeispiel;

Figur 2:

die Vorspannhakenflasche gemäß Figur 1 in entriegeltem Zustand und mit einem aufgenommenen Gewicht;

Figur 3:

einen Längsschnitt durch die erfindungsgemäße Vorspannhakenflasche;

Figur 4:

eine schematische Seitenansicht der Auslegerspitze eines Krans mit Tragmittel, Mastnase und Vorspannhakenflasche;

Figur 5:

eine Seitenansicht und eine Vorderansicht der erfindungsgemäßen Vorspannhakenflasche;

Figur 6:

eine schematische Darstellung der Verbindungsbereiche der oberen und unteren Hakenflaschenteile der erfindungsgemäßen Vorspannhakenflasche gemäß einem Ausführungsbeispiel;

Figur 7:

eine seitliche Ansicht des Oberwagens des Krans gemäß einem Ausführungsbeispiel mit angedeuteter Lage der Hubwinde; und

Figur 8-11:

verschiedene Stellungen von Tragmittel und Vorspannhakenflasche während der Durchführung des erfindungsgemäßen Hubverfahrens gemäß einem Ausführungsbeispiel, jeweils in einer seitlichen Gesamtansicht des Krans;

Further features, details and advantages of the invention result from the exemplary embodiments explained below with reference to the figures. Show it:

Figure 1:

a schematic side view of the pretensioning hook block according to the invention in a locked state suspended from a load hook of a crane according to an exemplary embodiment;

Figure 2:

the preload hook block according to figure 1 in the unlocked state and with a recorded weight;

Figure 3:

a longitudinal section through the pretensioning hook block according to the invention;

Figure 4:

a schematic side view of the boom tip of a crane with support means, mast nose and prestressing hook block;

Figure 5:

a side view and a front view of the pretensioning hook block according to the invention;

Figure 6:

a schematic representation of the connection areas of the upper and lower hook block parts of the pretensioning hook block according to an embodiment;

Figure 7:

a side view of the superstructure of the crane according to an embodiment with indicated position of the hoist winch; and

Figure 8-11:

different positions of the suspension means and pretensioning hook block during the implementation of the lifting method according to an exemplary embodiment, each in a lateral overall view of the crane;

the figure 1 shows a schematic side view of the pretensioning hook block 10 of the lifting system according to the invention according to a preferred embodiment. The pretensioning hook block 10 is suspended from a carrying means 6 of a crane 1, the exemplary embodiments shown here being a crawler crane 1.

The crane 1, which in a lateral overall view in the Figures 8-11 shown, comprises an undercarriage 8 with a crawler chassis, an uppercarriage 3 mounted on the undercarriage 8 so that it can rotate about a vertical axis, a boom 2 that is articulated on the uppercarriage 3 so that it can pivot about a horizontal axis, and a carrying element 6 for lifting loads, which is Embodiments shown here is designed as a roller block 6a with a load hook 6b.

The superstructure 3 of the crane 1 is isolated in a side view in FIG figure 7 shown. There is a hoist winch 5 on the superstructure 3, on which a hoist cable 4 is mounted so that it can be wound up and unwound. The hoist rope 4 is connected to the suspension means 6, so that the support means 6 can be raised and lowered by actuating the hoist winch 5 or by winding and unwinding the hoist cable 4 .

The crane 1 also has an auxiliary winch 14 on which an auxiliary cable 12 is mounted so that it can be wound up and unwound. Like in the figure 8 can be seen, the auxiliary winch 14 is located in the lower area of the boom 2.

Like in the figure 4 is indicated, the hoist rope 4 is guided over a deflection pulley of a pulley head on the boom tip to the hoist winch 5 . A deflection device 16 designed as a mast nose is mounted on the boom tip and has a deflection pulley over which the auxiliary cable 12 is guided.

The following will refer to the Figures 1-3 Reference is made, which shows the pretensioning hook block 10 according to the invention in a locked state ( 1 ) or in an unlocked state ( Figures 1-2 ) demonstrate. the figure 5 shows additional side and front views of the prestressing hook block 10.

The pretensioning hook block 10 according to the invention is constructed in two parts and comprises an upper hook block part 20 (upper block) and a lower hook block part 22 (lower block). On the upper side of the upper hook block part 20 there is a fastening means 21, via which the pretensioning hook block 10 can be attached or fastened to the load hook 6b of the crane 1. On the underside of the lower hook block part 22 there is a receiving means 23 in the form of a further load hook, to which a load or a weight 40 can be attached.

The two hook block parts 20, 22 can be locked together so that the prestressing hook block 10 can be moved or lifted as a whole (see 1 ). The locking can take place by means of one or more bolts 30 . As in particular in the figure 3 As can be seen, the upper hook block part 20 has a first deflection roller 24 , while the lower hook block part 22 has a second deflection roller 26 . The guided over the mast nose 16 auxiliary cable 12 is outgoing guided or reeved from the nose of the mast 16 over the second deflection roller 26 of the lower hook block part 22 and then over the first deflection roller 24 of the upper hook block part 20 and connected to the lower hook block part 22 via a fastening means 29 . Furthermore, the upper hook block part 20 has a further deflection roller 28 in order to guide the auxiliary rope 12 laterally past the suspension means 6 . The two hook block parts 20, 22 are connected to one another via the auxiliary cable 12 in such a way that the distance between the two hook block parts 20, 22 from one another can be changed by suitably controlling the auxiliary winch 14.

Using the pretensioning hook block 10 according to the invention in combination with the auxiliary winch 14, the auxiliary rope 12 and the mast nose 16, a sufficiently high pretension can be generated on the hoisting rope 4 when lifting the suspension element 6, so that it is wound up tightly onto the hoisting winch 5. This prevents the occurrence of cutting and ensures good winding quality.

If the suspension means 6 is to be lifted by the crane 1 for the purpose of dismantling a higher component without a suspended load, a weight 40 is attached to the receiving means 23 of the lower hook block part 22 of the pretensioning hook block 10 attached to the suspension means 6, as shown in Fig figure 2 is shown. The weight 40 is connected to the suspension means 6 and thus to the hoist rope 4 via the prestressing hook block 10 and generates a suitable prestressing force.

The block and tackle of the pretensioning hook block 10 realized by the deflection rollers 24, 26 and the fastening means 29 causes the weight force of the weight 40 fastened to the receiving means 23 to be divided between the different strands of the auxiliary rope 12. Since the reeving of the auxiliary rope 12 of the prestressing hook block 10 is selected with three reevings, with the first line leading to the mast nose 16, two lines contribute to increasing the pretension, i.e. approx. 2/3 of the ballast weight 40 hangs on the suspension element 6 and tensions it Hoist rope 4, which is wound onto the hoist winch 5. Of course, more than three reevings of the auxiliary rope 12 or more than one deflection roller 24, 26 can be provided on the hook block parts 20, 22.

The two deflection rollers 24, 26 have parallel axes of rotation. The fastening means 29 is located above the second deflection roller 26 on the lower hook block part 22, while the receiving means 23 is arranged below the second deflection roller 26. The other deflection roller 28 is located diagonally above the first deflection roller 24 on the upper hook block part 20, while the fastening means 21 is arranged above the first deflection roller 24.

Like in the figure 4 As can be seen, the distance between the first deflection pulley 24 and the further deflection pulley 28 can essentially correspond to the distance between the corresponding deflection pulleys for the hoist rope 4 and the auxiliary rope 12 at the boom head and at the mast nose 16, respectively.

Like in the figure 5 As can be seen, the two hook block parts 20, 22 can be pushed into one another, with the upper hook block part 20 being pushed with a receiving area 34 designed as a spring into a receiving area of the lower hook block part 22 designed as a groove 32. The receiving areas 32, 34 can be bevelled, which makes threading or pushing in easier.

As described above, the two hook block parts 20, 22 can be locked manually using bolts 30 (see also figure 5 ). In the figure 6 an alternative embodiment is shown in sketch form, in which the pretensioning hook block 10 has a locking mechanism. Accordingly, a retaining bolt 38 is arranged in the upper area of the lower hook block part 22 , while a pivotable hook element 36 is located in the lower area of the upper hook block part 20 . When the two hook block parts 20, 22 are brought together, the pin 38 automatically pushes the hook 36 aside and pivots it about its pivot axis, as shown. When the hook block parts 20, 22 reach their fully retracted locking position, the hook 36 snaps in and automatically locks the two hook block parts 20, 22. A spring element, not shown in detail, can be provided for this purpose, which forces the hook 36 into its locking position. As a result, the hook block parts 20, 22 do not have to be locked manually, which facilitates merging, especially at great heights.

the Figures 8-11 show a lateral overall view of the crane 1 during a lift of the support means 6 according to an exemplary embodiment of the method according to the invention. This is based on the situation that a load is to be picked up from an elevated position and set down on the floor 9 for dismantling. In order to be able to lift the suspension element 6 with sufficient pretension to the level of the load to be picked up, in a first step the previously lowered suspension element 6 is connected to a weight 40 via the pretensioning hook block 10 according to the invention. The pretensioning hook block 10 is attached to the load hook 6b in the locked state. The weight 40 is attached to the receiving means 23 of the pretensioning hook block 10 . The prestressing hook block 10 can either already be connected to the auxiliary rope 12 when it is attached to the load hook 6b or, for example during the first lift, the auxiliary rope 12 is reeved into the prestressing hook block 10 after it has been attached.

Now the prestressing hook block 10 is unlocked or bolted apart and the weight 40 is slightly raised by operating the hoist winch 5 and the auxiliary winch 14 (see 8 ). Here, the weight 40 can lift off the ground. By winding up the hoist winch 5 and simultaneously unwinding the auxiliary winch 14, preferably by appropriate control and monitoring of the crane control, the weight 40 can be kept floating close to the ground 9 during the lifting of the support means 6. As long as the weight 40 is in the floating state, its weight applies a high pretension to the hoist rope 4 or the hoist winch 5 .

After the suspension element 6 has been completely raised via the hoist rope 4 by means of the hoist winch 5, ie to the desired height (see 9 ), the auxiliary winch 14 is unwound, the lower hook block part 22 of the pretensioning hook block 10 is lowered and the weight 40 is placed on the floor 9 and unhooked.

The lower hook block part 22 is then pulled up by winding up the auxiliary winch 14 and brought up to the upper hook block part 20 . When the hook block parts 20, 22 are in their locked position, they can be bolted together (or automatic locking will take place as discussed above). This can be done from the elevated position, where the load to be transported or set down must also be picked up. the figure 10 shows the situation after the hook block parts 20, 22 have been brought together and locked, while the pretensioning hook block 10 is still attached to the suspension element 6.

The pretensioning hook block 10 can now be detached from the suspension means 6 of the crane 1 (see 11 ) and then lowered to the ground 9 by means of the auxiliary winch 14. The carrying means 6 is still in the elevated position and can now be connected to the load to be transported. The load can be set down on the floor 9 by operating the hoist winch 5 . The steps explained above can be carried out again for the next lift of the suspension element 6 .

An advantage of this method is the weight 40 lifted from the ground 9, which means that the entire pretensioning process can be monitored by the control of the crane 1. The prestressing process corresponds to regular crane operation. In this case, it is a monitored two-hook operation with a hook 6b on the main or hoist winch 5 as the main hoist and a hook 23 on the auxiliary winch 14 via the mast nose 16 with a common load.

With this solution, no modifications to the crane 1 are necessary, which would require a separate static consideration. Furthermore, no auxiliary vehicle has to be used to apply the prestress. The auxiliary winch 14 for the auxiliary hoist and the short mast nose 16 are standard equipment on many lattice boom cranes and also on large telescopic cranes. During the prestressing process, the crane 1 can also be rotated and/or moved, which is not possible with a solution using an auxiliary vehicle and/or an auxiliary winch parked on the ground.

Reference list:

1

crane

2

boom

3

superstructure

4

hoist rope

5

hoist winch

6

carrying means

6a

roller block

6b

load hook

8th

undercarriage

9

floor

10

pre-tension hook bottle

12

auxiliary rope

14

auxiliary winch

16

deflection device (mast nose)

20

Upper hook block part

21

fasteners

22

Lower hook block part

23

Pick-up device (load hook)

24

First pulley

26

Second pulley

28

pulley

29

Auxiliary rope fasteners

30

bolt

32

groove

34

Feather

36

hook

38

bolt

40

weight

Claims (16)

Lifting system for a crane (1), in particular a mobile or crawler crane, for generating a hoist cable pretension during a hoist of a suspension element (6) of the crane (1), comprising a divisible pretensioning hook block (10) and an auxiliary cable (12) connected thereto, which mounted on an auxiliary winch (14) arranged or mountable on the crane (1) so that it can be wound up and unwound and guided over a deflection device (16) arranged or mountable on a boom (2) of the crane (1), the pretensioning hook block (10) having two hook block parts (20, 22) that can be releasably locked together and are connected to one another via the auxiliary rope (12), of which an upper hook block part (20) has a fastening means (21) for fastening to the carrying means (6) and a lower hook block part (22) has a receiving means ( 23) for attaching a weight (40). Lifting system according to claim 1, wherein the pretensioning hook block (10), the upper hook block part (20) comprises at least one first deflection pulley (24) and the lower hook block part (22) comprises at least one second deflection pulley (26) over which the auxiliary rope (12) is guided . Lifting system according to claim 1 or 2, wherein the pretensioning hook block (10) has at least one deflection pulley (28) for guiding the auxiliary rope (12) laterally past the support means (6), which is preferably arranged on the upper hook block part (20). Lifting system according to one of the preceding claims, wherein the pretensioning hook block (10) comprises a guide mechanism by means of which the lower and upper hook block parts (20, 22) can be brought into a defined locking position when brought together, the guide mechanism preferably having one or more guide rails and/or a Includes tongue and groove mechanism (32, 34). Lifting system according to one of the preceding claims, wherein the lower and upper hook block parts (20, 22) have connecting means for releasable locking with one another, the lower and upper hook block parts (20, 22) preferably being bolted by means of one or more bolts (30). Lifting system according to one of the preceding claims, in which the lower and upper hook block parts (20, 22) can be locked by means of an actuatable locking mechanism (36, 38), the locking mechanism (36, 38) preferably being activated during or after the hook block parts (20, 22 ) can be activated actively or passively. A hoist system according to claim 6, wherein the locking mechanism is adapted to lock automatically when the lower and upper hook block parts (20, 22) are brought together and preferably comprises a spring element and/or a (36, 38) snap mechanism. Hoisting system according to one of the preceding claims, further comprising a hoisting winch (5) on which a hoisting rope (4) connected to the support means (6) is mounted so that it can be wound up and unwound, the hoisting winch (5) and the auxiliary winch (14) preferably being independent can be actuated from one another and as a result the suspension means (6) and the pretensioning hook block (10) can be lifted independently of one another. Hoisting system according to Claim 8, further comprising a crane controller which is set up to control the hoisting winch (5) and the auxiliary winch (14) in a synchronized manner such that during a lift of the support element (6) by winding up the hoisting winch (5) and simultaneously unwinding the auxiliary winch (14) a weight (40) fastened to the unlocked pretensioning hook block (10) is kept floating above the ground (9) at a certain height or in a certain area. Crane (1), in particular a mobile or crawler crane, with a lifting system according to one of the preceding claims, the carrying means (6) preferably being a bottom hook block and/or the deflection device (16) being a mast nose that can be mounted on the boom tip and/or the auxiliary winch (14) is arranged on a superstructure (3) of the crane (1). Prestressing hook block (10) of a lifting system according to one of Claims 1 to 9, with an auxiliary cable fastening means (29) for fastening the auxiliary cable (12), which is preferably arranged on the lower hook block part (22). Method for lifting a carrying element (6) of a crane (1) using a lifting system according to one of Claims 1 to 9, with the steps: - Fastening the pretensioning hook block (10) to the lowered lifting gear (6), - unlocking the upper and lower hook block parts (20, 22), - attaching a weight (40) to the lower hook block part (22), - lifting of the suspension means (6), in particular by winding up a hoist rope (4) connected to the suspension means (6) on a hoist winch (5), as a result of which the lower and upper hook block parts (20, 22) move away from one another, - depositing the weight (40) by unwinding the auxiliary winch (14) while the support means (6) is in a raised position and releasing the lower hook block part (22) from the weight (40). A method according to claim 12, wherein after the weight (40) is deposited and released, the lower hook block part (22) is removed by winding up the auxiliary winch (14) and brought together with the upper hook block part (20) so that the hook block parts (20, 22) can be locked together, with the locked pretensioning hook block (10) then preferably being released from the carrying means (6) and being unwound by unwinding the auxiliary winch (14 ) is deposited on the ground (9). Method according to claim 12 or 13, wherein the hoist winch (5) and the auxiliary winch (14) are controlled synchronously or synchronized for the lifting of the support means (6), in particular via a crane control of the crane (1), that by winding up the hoist winch ( 5) and simultaneous unwinding of the auxiliary winch (14), the weight (40) is held at a certain height, in particular floating above the ground (9). Method according to Claim 14, in which the lifting of the carrying means (6) takes place in a two-hook operation monitored by the crane control, the lifting and auxiliary winches (5, 14) preferably being automatically regulated by the crane control in such a way that the weight (40) is held at a defined height above the ground (9) and/or in a specific position. Use of a lifting system according to one of Claims 1-9, with the steps: - Fastening the pretensioning hook block (10) to the lowered load handling device (6), - unlocking the upper and lower hook block parts (20,22), - attaching a weight (40) to the lower hook block part (22), - raising the suspension means (6), in particular by winding up a cable (4) connected to the suspension means (6) and a winch (5), as a result of which the lower and upper hook block parts (20, 22) move away from one another, and - Simultaneous unwinding of the auxiliary winch (14) in such a way that the weight (40) remains on the ground and there is a constant pull in the auxiliary winch cable.

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