EP4091980B1 - Lifting system and method for a crane - Google Patents

Description

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

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

If dismantling operations are carried out by the crane (e.g. chimney dismantling or wind turbine dismantling), loads often have to be picked up at great heights and placed on the ground. To do this, the hook block is “empty” spooled up, i.e. lifted without a load, the load is then picked up at a height and then placed on the ground.

This means that when the hook block is lifted, the lower layers of the hoist rope are only pre-tensioned using the hook block's own weight when it is wound onto the hoist winch and the high load is only absorbed on the top layer of the winch. The risk of rope cutting and therefore rope damage and even ropes being discarded is therefore very high during such dismantling processes.

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

Furthermore, the possibility of pulling up an additional weight together with the otherwise empty load hook and placing it on the building or similar is known from the prior art. This has the same effect as increasing the weight of the hook block, but has the advantage that the additional weight does not remain on the hook block during the actual load lift from height to the ground and so the available load capacity is not reduced. The disadvantage here is that in most cases there is no possibility of depositing or storing such 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 pre-tensioning winch is known, which pulls on the load hook on the ground with a ballast weight and thus creates additional pre-tension on the hoist rope. However, this requires the provision of another support vehicle at the construction site.

The US 2010/072158 A1 , which is considered to be the closest prior art, discloses a crawler crane with a generic lifting system. The EP 2 402 281 A1 discloses a tower crane, the hoist rope of which is guided over an auxiliary deflection in order to unwind the hoist rope area that is not unwound during normal operation and to rewind it under pretension. The US 4,081,081 A discloses a crawler crane with a boom that can be removed from the superstructure and guy stands, which can be moved into a folded position on the superstructure after the boom has been dismantled.

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 to use 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 with the features of claim 1, a pretensioning hook block with the features of claim 11 and a method according to claim 12. Advantageous embodiments of the invention result from the subclaims and the following description. Accordingly, a lifting system for a crane, in particular a mobile or crawler crane, is proposed for generating a hoist cable pretension during a hoist of a suspension element of the crane. The lifting system according to the invention comprises a divisible pre-tensioning hook block and an auxiliary rope connected to it, which is mounted so that it can be wound up and unwound on an auxiliary winch arranged or mountable on the crane and is guided via a deflection device arranged or mountable on a boom of the crane. By winding and unwinding the auxiliary rope, the pre-tensioning 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 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 element 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 element, 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 divisibility of the pre-tensioning hook block, the two hook block parts can be moved in particular independently of one another and the weight associated with the lower hook block part does not have to be lifted together with the suspension element when it is lifted. By cleverly controlling or regulating the auxiliary winch, the position or movement of the weight connected to the lower hook block part can be controlled precisely and safely, for example via a crane control of 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 appropriately controlling the auxiliary winch. For example, after lifting the suspension element to a desired height by appropriately controlling the auxiliary winch, the weight connected to the lower hook block part can be placed back on the ground and detached from the lower hook block part, 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 brought together and locked if necessary. Since the pre-tensioning hook bottle "hangs" on the separate auxiliary rope, the pre-tensioning hook bottle can be detached from the suspension element in the elevated position, so that the latter is available to hold a part to be dismantled.

The lifting system according to the invention therefore makes it possible to exert a pre-tensioning force on the lifting rope by using an additional weight when lifting the "empty" suspension element and thus guarantee good winding quality, whereby no external auxiliary devices or vehicles need to be used other than the weight. The weight that generates the preload force does not have to be in an elevated position but can remain on 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 be carried.

With the solution described, the load can be kept close to the ground. This is an improvement in security aspects. There are always dangers in the area under a suspended load and people should avoid the area.

Since many cranes, for example lattice boom cranes (i.e. cranes with lattice booms), already have an auxiliary winch with an auxiliary rope and a mast nose that can be mounted on the boom tip as standard equipment, in such a case only the pre-tensioning hook block according to the invention needs to be connected to the auxiliary rope. This doesn't take up much space and can easily be carried on the crane. Therefore, 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 separate static consideration. The lifting system according to the invention can easily be retrofitted to existing cranes or added for individual applications and then dismantled again.

When it is said here that the auxiliary winch or hoisting winch is wound up or unwound or spooled up or unwound, this is intended to express in a shortened notation that the corresponding auxiliary rope or hoisting rope is wound up or unwound on or from the winch . is 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 is to be understood as meaning that the auxiliary rope runs between these two hook block parts. The two hook block parts are movable in particular relative to one another.

In a possible embodiment it is provided that at least a first deflection roller is arranged on the upper hook block part and a second deflection roller on the lower hook block part, over which the auxiliary rope is guided. This means that the pre-tensioning hook block has at least two reevings for the auxiliary rope.

The reeving of the auxiliary rope can be carried out in such a way that its end is attached to the lower hook block part. Together with a deflection roller provided on the deflection device, this results in a total of three strands in the simplest case that the lower and upper hook block part each have exactly one deflection roller, 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 across the various strands of the pulley. In the case of three strands, two strands contribute to increasing the pre-tension, so that approx. 2/3 of the weight hangs on the suspension element and tensions the hoist rope, which is wound onto the hoist winch.

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

In a further possible embodiment it is provided that the pre-tensioning hook block has at least one deflection roller for guiding the auxiliary rope laterally past the suspension means, which is preferably arranged on the upper hook block part. This additional deflection roller is therefore not used to reeve the auxiliary rope in order to distribute the weight of the additional weight, but rather merely to guide the auxiliary rope past. Alternatively, it is also conceivable that one of the deflection rollers of the pulley is used at the same time to guide it 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 brought together. The guide mechanism can serve to precisely align 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 comprises one or more guide rails. Alternatively or additionally, the guide mechanism may comprise a tongue and groove mechanism, wherein the groove may be attached to the lower hook block and the tongue may 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 an elevated position without the need for manual assistance.

In a further possible embodiment it is provided that the lower and upper hook block parts have connecting means for releasably locking them together. The connecting means preferably enable the lower and upper hook block parts to be bolted together using 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 during or after the upper and lower hook block parts have been brought together. Active actuation can take place, for example, using electrically or hydraulically controlled locking bolts. However, passive actuation of the locking mechanism is preferred, in particular triggered when the upper and lower hook block parts are brought together. This means that the prestressing hook block can be designed to be structurally simple.

In a further possible embodiment it is provided that the locking mechanism is designed when merging the lower and upper To automatically lock hook block parts 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 bottle part in such a way that when the other hook bottle part is brought together, the hook element pivots and the latter snaps back into a locking position of the upper and lower hook element by a spring mechanism and a bolt on the other hook bottle part in this way encompasses 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 latch.

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

In a further possible embodiment, a lifting winch is also provided, on which a lifting rope connected to the suspension means is mounted so that it can be wound up and unwound, the lifting winch and the auxiliary winch preferably being able to be actuated independently of one another and thereby the carrying means and the pretensioning hook block being able to be lifted independently of one another. The lifting winch and the auxiliary winch can preferably be operated by a crane control.

In a further possible embodiment, a crane control is also provided, which is set up to control the lifting winch and the auxiliary winch in a synchronized manner in such a way that during a stroke of the suspension means by winding up the lifting winch and simultaneously unwinding the auxiliary winch, a weight attached to the unlocked pre-tensioning hook bottle is at a certain height is kept 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 system.

Advantageously, the entire prestressing process can be carried out and monitored by the crane control. The pretensioning process can therefore correspond to a regular crane operation, for example a monitored two-hook operation, with a hook on the suspension element as the main lift, actuated by the lifting winch, and a hook on the pretensioning hook block, actuated by the auxiliary winch, with a common load.

The present invention further relates to a crane, in particular a mobile or crawler crane, which comprises the lifting system according to the invention. Preferably, both the lifting winch and the auxiliary winch are attached to a superstructure of the crane and can be operated 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 roller 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 fastening means. This obviously results in the same advantages and properties as for the lifting system according to the invention, which is why a repeat description is omitted here. The above statements regarding the possible configurations of the pre-tensioning 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 suspension element of a crane using the lifting system according to the invention with the following steps:

• Attaching the pre-tensioning hook bottle to the suspension element,
• 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 the suspension means, in particular by winding a hoist rope connected to the suspension means onto a lifting winch, whereby the lower and upper hook block parts move away from each other (ie the upper hook block part is pulled upwards together with the suspension means, while the lower hook block part remains under weight), and
• Place the weight on the ground after lifting the lifting gear by unwinding the auxiliary winch while the lifting gear is in its raised position and releasing the lower hook block part 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 repeat description is omitted here.

The first three steps can be performed in any order.

In a 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 pre-tensioning hook block preferably then being released from the suspension means and is deposited on the ground by unwinding the auxiliary winch. Now the suspension element can, for example, be connected to a part that is to be dismantled at a great height and the part can be lowered to the ground. The process can then be repeated so that sufficient pre-tensioning force is available for the hoist rope with each stroke of the "empty" suspension element.

Accessibility for hanging the pre-tensioning hook block from the suspension element can be assumed as given, since in the subsequent step the load to be dismantled must be attached to the suspension element.

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

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

An inventive use of the system, as presented previously, 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 and suspended from a load hook of a crane according to an exemplary embodiment;

Figure 2:

the pre-tensioning hook block according to Figure 1 in unlocked condition and with a weight picked up;

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 suspension means, mast nose and pre-tensioning hook block;

Figure 5:

a side view and a front view of the tensioning 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 the invention according to an exemplary embodiment;

Figure 7:

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

Figure 8-11:

different positions of the suspension element and pre-tensioning hook block during the implementation of the lifting method according to the invention according to an exemplary embodiment, each in an overall side view of the crane;

The Figure 1 shows a schematic side view of the pretensioning hook bottle 10 of the lifting system according to the invention according to a preferred exemplary embodiment. The pretensioning hook block 10 is suspended on a suspension element 6 of a crane 1, the exemplary embodiments shown here being a crawler crane 1.

The crane 1, which is shown in an overall side view in the Figures 8-11 is shown, comprises an undercarriage 8 with a crawler chassis, an uppercarriage 3 rotatably mounted on the undercarriage 8 about a vertical axis, a boom 2 articulated about a horizontal axis on the superstructure 3 and a Suspension means 6 for lifting loads, which in the exemplary embodiments shown here is designed as a roller block 6a with a load hook 6b.

The uppercarriage 3 of the crane 1 is isolated in a side view in the Figure 7 shown. On the superstructure 3 there is a hoist winch 5, on which a hoist rope 4 is mounted so that it can be wound up and unwound. The lifting rope 4 is connected to the suspension element 6, so that the suspension element 6 can be raised and lowered by operating the lifting winch 5 or by winding and unwinding the lifting rope 4.

The crane 1 also has an auxiliary winch 14, on which an auxiliary rope 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 to the hoist winch 5 via a deflection roller of a roller head at the boom tip. A deflection device 16 designed as a mast nose is mounted on the boom tip and has a deflection roller over which the auxiliary rope 12 is guided.

Below we will refer to the Figures 1-3 Reference is made to the biasing hook bottle 10 according to the invention in a locked state ( Fig. 1 ) or in an unlocked state ( Fig. 1-2 ) show. The Figure 5 additionally shows side and front views of the pre-tensioning 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 (top block) and a lower hook block part 22 (bottom block). On the top of the upper hook block part 20 there is a fastening means 21, via which the pre-tensioning 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 another 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 preload hook block 10 can be moved or lifted as a whole (see Fig. 1 ). The locking can be done using one or more bolts 30. Like especially in the Figure 3 can be seen, the upper hook block part 20 has a first deflection roller 24, while the lower hook block part 22 includes a second deflection roller 26. The auxiliary rope 12 guided over the mast nose 16 is guided or reeved starting from the mast nose 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 element 6. The two hook block parts 20, 22 are connected to one another via the auxiliary rope 12 in such a way that the distance between the two hook block parts 20, 22 from one another can be changed by suitable control of the auxiliary winch 14.

By means of 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 tightly onto the hoisting winch 5. This prevents the occurrence of cuts and ensures good wrapping quality.

If the suspension element 6 is to be lifted by the crane 1 for the purpose of dismantling a higher component without an attached 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 element 6, as in the Figure 2 is shown. The weight 40 is connected to the suspension element 6 and thus to the hoist rope 4 via the pretensioning hook bottle 10 and generates a suitable pretensioning force.

The pulley of the pretensioning hook bottle 10, which is realized by the deflection rollers 24, 26 and the fastening means 29, causes the weight of the weight 40 attached to the receiving means 23 to be distributed among the different strands of the auxiliary rope 12. Since the reeving of the auxiliary rope 12 of the prestressing hook block 10 is chosen with three reevings, with the first strand leading to the mast nose 16, two strands contribute to increasing the pre-tension, ie approx. 2/3 of the ballast weight 40 hangs on the suspension element 6 and tensions the hoist rope 4, which is on the hoist winch 5 is wound up. 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 further deflection roller 28 is located obliquely 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 can be seen, the distance between the first deflection roller 24 and the further deflection roller 28 can essentially correspond to the distance between the corresponding deflection rollers for the hoist rope 4 and the auxiliary rope 12 on the boom head or on the mast nose 16.

Like in the Figure 5 can be seen, the two hook block parts 20, 22 can be pushed into one another, the upper hook block part 20 being inserted 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 beveled, which makes threading or inserting easier.

As described above, the two hook block parts 20, 22 can be locked manually via bolts 30 (see also Fig. 5 ). In the Figure 6 An alternative exemplary embodiment is shown in outline, in which the preload hook bottle 10 has a locking mechanism. Accordingly, a retaining bolt 38 is arranged in the upper region of the lower hook block part 22, while a pivotable hook element 36 is located at the lower region of the upper hook block part 20. When the two hook block parts 20, 22 are brought together the bolt 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 into place and automatically locks the two hook block parts 20, 22. For this purpose, a spring element (not shown) can be provided, 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 makes bringing them together easier, especially at great heights.

The Figures 8-11 show an overall side view of the crane 1 during a stroke of the suspension element 6 according to an exemplary embodiment of the method according to the invention. This assumes the situation that a load is to be picked up from an elevated position and placed on the ground 9 for dismantling. In order to be able to lift the suspension element 6 with sufficient pretension to the height 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 pretension hook bottle 10 according to the invention. The pretensioning hook bottle 10 is attached to the load hook 6b in the locked state. The weight 40 is attached to the receiving means 23 of the preload hook bottle 10. When hanging on the load hook 6b, the pre-tensioning hook bottle 10 can either already be connected to the auxiliary rope 12 or, for example during the first stroke, the auxiliary rope 12 is reeved into the pre-tensioning hook bottle 10 after it has been attached.

Now the pre-tensioning hook block 10 is unlocked or unscrewed and the weight 40 is slightly raised by operating the lifting winch 5 and the auxiliary winch 14 (see Fig. 8 ). The weight can lift 40 off the ground. By winding up the lifting 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 close to the ground 9 during the lifting of the suspension element 6, in particular floating. As long as the weight 40 is in a 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 pulled up over the hoist rope 4 using the hoist winch 5, ie to the desired height (see Fig. 9 ), the auxiliary winch 14 is unwound, the lower hook block part 22 of the pre-tensioning hook block 10 is lowered and the weight 40 is placed on the floor 9 and hung out.

The lower hook block part 22 is then pulled up by winding up the auxiliary winch 14 and brought to the upper hook block part 20. When the hook block parts 20, 22 are in their locking position, they can be bolted together (or automatic locking takes place as explained 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 pre-tensioning hook block 10 is still attached to the suspension element 6.

The pre-tensioning hook block 10 can now be suspended from the suspension element 6 of the crane 1 (see Fig. 11 ) and then lowered to the ground 9 using the auxiliary winch 14. The suspension element 6 is still in the elevated position and can now be connected to the load to be transported. By operating the lifting winch 5, the load can be placed on the floor 9. For the next stroke of the suspension element 6, the steps explained above can be carried out again.

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

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

List of reference symbols:

1

crane

2

boom

3

Uppercarriage

4

lifting rope

5

Hoist winch

6

carrying means

6a

Roller trestle

6b

Load hook

8th

Undercarriage

9

Floor

10

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

Lifting equipment (load hook)

24

First pulley

26

Second pulley

28

pulley

29

Auxiliary rope fasteners

30

bolt

32

Nut

34

Feather

36

Hook

38

bolt

40

Weight

Claims (16)

1. A lifting system for a crane (1), in particular for a mobile crane or crawler crane, for generating a hoist rope pretension during a travel of a suspension element (6) of the crane (1) comprising a pretension hook block (10) and an auxiliary rope (12) that is connected thereto, that is supported in a windable and unwindable manner on an auxiliary winch (14) arranged or installable on the crane (1), and that is guided via a deflection apparatus (16) that is arranged or installable at a boom (2) of the crane (1), characterized in that the pretension hook block (10) comprises two hook block parts (20, 22) that are releasably lockable to one another, that are connected to one another via the auxiliary rope, and of which an upper hook block part (20) has a fastening means (21) for fastening to the suspension element (6) and a lower hook block part (22) has a pick-up means (23) for fastening a weight (40).
2. A lifting system in accordance with claim 1, wherein the pretension 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) via which the auxiliary rope (12) is guided.
3. A lifting system in accordance with claim 1 or claim 2, wherein the pretension hook block (10) has at least one deflection pulley (28) to lead the auxiliary rope (12) laterally past the suspension element (6) that is preferably arranged at the upper hook block part (20).
4. A lifting system in accordance with one of the preceding claims, wherein the pretension 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 locked position on the bringing together, with the guide mechanism preferably comprising one or more guide rails and/or a tongue-in-groove mechanism (32, 34).
5. A lifting system in accordance with one of the preceding claims, wherein the lower and upper hook block parts (20, 22) have connections means for the releasable locking to one another, with the lower and upper hook block parts (20, 22) preferably being able to be pinned by means of one or more pins (30).
6. A lifting system in accordance with one of the preceding claims, wherein the lower and upper hook block parts (20, 22) are lockable by means of an actuable locking mechanism (36, 38), with the locking mechanism (36, 38) preferably being actively or passively actuable on or after the bringing together of the hook block parts (20, 22).
7. A lifting mechanism in accordance with claim 6, wherein the locking mechanism is adapted to lock automatically on the bringing together of the lower and upper hook block parts (20, 22) and preferably comprises a spring element and/or a snap-in mechanism (36, 38).
8. A lifting system in accordance with one of the preceding claims, further comprising a hoist winch (5) on which a hoist rope (4) connected to the suspension element (6) is supported in a windable and unwindable manner, with the hoist winch (5) and the auxiliary winch (14) preferably being actuable independently of one another and the suspension element (6) and the pretension hook block (10) thereby being liftable independently of one another.
9. A lifting system in accordance with claim 8, further comprising a crane control that is configured to control the hoist winch (5) and the auxiliary winch (14) synchronized such that a weight (40) fastened to the unlocked pretension hook block (10) is held suspended at a certain height or in a certain region above the ground (9) during a travel of the suspension element (6) by reeling up the hoist winch (5) and simultaneously unreeling the auxiliary winch (14).
10. A crane (1), in particular a mobile crane or a crawler crane, having a lifting system in accordance with one of the preceding claims, wherein the suspension element (6) is preferably a hook block and/or wherein the deflection apparatus (16) is a mast nose installable at the boom tip and/or the auxiliary winch (14) is arranged at a superstructure (3) of the crane (1).
11. A pretension hook block (10) of a lifting system in accordance with one of the claims 1 to 9 having an auxiliary rope fastening means (29) for fastening the auxiliary rope (12) that is preferably arranged at the lower hook block part (22).
12. A method of lifting a suspension element (6) of a crane (1) using a lifting system in accordance with one of the claims 1 to 9, the method comprising the steps:

    - fastening the pretension hook block (10) to the lowered suspension element (6);

    - unlocking the upper and lower hook block parts (20, 22);

    - fastening a weight (40) to the lower hook block part (22);

    - lifting the suspension element (6), in particular by reeling a hoist rope (4) connected to the suspension element (6) on a hoist winch (5), whereby the lower and upper hook block parts (20, 22) move away from one another; and

    - placing the weight (40) down by unreeling the auxiliary winch (14) while the suspension element (6) is in its raised position and releasing the lower hook block part (22) from the weight (40).
13. A method in accordance with claim 12, wherein the lower hook block part (22) is raised by reeling up the auxiliary winch (14) and is brought together with the upper hook block part (20) after the placing down and releasing of the weight (40) so that the hook block parts (20, 22) can be locked to one another, with the locked pretension hook block (10) subsequently preferably being released from the suspension element (6) and being placed on the ground (9) by unreeling the auxiliary winch (14).
14. A method in accordance with claim 12 or claim 13, wherein the hoist winch (5) and the auxiliary winch (14) are controlled synchronously or synchronized for the travel of the suspension element (6), in particular via a crane control of the crane (1), such that the weight (40) is held at a certain height above the ground (9), in particular suspended, by reeling up the hoist winch (5) and simultaneously unreeling the auxiliary winch (14).
15. A method in accordance with claim 14, wherein the travel of the suspension element (6) takes place in a two-hook operation monitored by the crane control, with an automatic regulation of the hoist and auxiliary winches (5, 14) preferably taking place by the crane control such that the weight (40) is held at a defined height above the ground (9) and/or in a specific location.
16. Use of a lifting system in accordance with one of the claims 1 to 9, comprising the steps:

    - fastening the pretension hook block (10) to the lowered suspension element (6);

    - unlocking the upper and lower hook block parts (20, 22);

    - fastening a weight (40) to the lower hook block part (22);

    - lifting the suspension element (6), in particular by reeling a rope (4) connected to the suspension element (6) and a winch (5), whereby the lower and upper hook block parts (20, 22) move away from one another; and

    - simultaneous unreeling the auxiliary winch (14) such that the weight (40) remains on the ground and a constant strand tension is present in the auxiliary winch rope.

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