EP1135322B1

EP1135322B1 - Crane, especially a self-propelled crane

Info

Publication number: EP1135322B1
Application number: EP99963282A
Authority: EP
Inventors: Manfred Kretschmer; Alfons Weckbecker
Original assignee: Demag Mobile Cranes GmbH and Co KG
Current assignee: Demag Mobile Cranes GmbH and Co KG
Priority date: 1998-12-04
Filing date: 1999-11-29
Publication date: 2003-07-09
Anticipated expiration: 2019-11-29
Also published as: US6568547B1; EP1135322A1; WO2000034173A1; AT244677T; DE19857779A1; AU1964700A; JP2002531357A; JP4454861B2

Description

The invention relates to a crane, in particular a vehicle crane with a Substructure and a rotatably mounted on this upper carriage according to the preamble of claim 1.

Cranes with an arrangement of a mast and a superlift counterweight are for high Traglastenmomente designed. The required counterweight torque is generated via the superlift counterweight, which at a certain distance to the Crane is arranged. To increase the flexibility of the crane d. H. different Load bearing moments at different locations with the least possible effort To be able to control while maintaining the mobility and rotation of the Cranes, various suggestions have been made.

A proposal for a mobile crane shows the DE 28 14 540 C2. One is revealed mobile crane with a rotatable superstructure with a load beam and a Counter-jib carrying a superlift counterweight, which at every load of the Cranes are supported on the ground so that the superstructure can turn. to Ground support is an air cushion used, the filling according to the Force determined on the counter-jib is changeable. This arrangement requires in addition a compressor including the associated lines, what the Handling not relieved. Also, the distance of the superlift counterweight to the crane will not be changed.

Another embodiment, the DE-PS 195 03 73. In this vehicle crane is the superlift counterweight formed in the form of a steerable car, the over Articulated connections is rigidly connected to the superstructure of the vehicle crane. When lifting a load, the counterweight carriage is raised and can be pivoted together with the crane. The arrangement of a counterweight car is complex and its installation depending on the conditions of the terrain difficult. The distance between the counterweight car and the vehicle crane is not variable. In addition, the height of the lifting of the counterweight car is ever can not be influenced by the size of the load to be lifted. With suddenly falling load The counterweight car would not only open, depending on the lift height, but could even come to tipping.

A variant of this known construction is shown in US Patent 4,258,852. The distance of the superlift counterweight from the vehicle crane can by a certain amount to be changed. This is done with the superlift counterweight on a changeable bracing associated mast according inclined and through Replacing certain lattice mast elements of the superlift counterweight Distance to the crane holding lattice mast the distance by the length of the changed lattice mast element changed. The disadvantage of this construction is that the change in distance only by certain amounts possible and to one Remodeling is required. In addition, by attaching a load of the Counterweight cars are brought to lift. When arranging two Counterweight must also be the distance between these two with be adjusted.

Another construction is shown in U.S. Patent 4,557,390. In this embodiment, the mast is articulated to a frame arranged in the rear end region of the superstructure and is held in a fixed angular position by connectable to the superstructure rod elements. The top of the mast is connected to the tip of the main boom via a length-adjustable bracing, as well as the top of the mast with a superlift counterweight. It is dispensed with the arrangement of an otherwise usual Oberwagengegengewichtes. By means of a pulley arrangement, the distance of the superlift counterweight to the crane can be changed continuously. The lifting of the superlift counterweight takes place via a winch motor arranged on the superstructure. By means of a spacer bar arranged on the superlift counterweight, the lifting distance of the superlift counterweight to the ground can be controlled. A disadvantage of this construction is that the superlift counterweight is not displaced beyond the mast radius out. Another disadvantage is that the mast must be erected from the rear and an angular adjustment of the mast is possible only via a set-up by changing the number of mast positioning rod elements. In addition, the weight of the substructure to increase the stability can not be used. In a company brochure from Manitowoc Engineering Co. (Complete Line Brochure), 1992 edition, a vehicle crane is presented under the brand name X-Spander, which has a continuously displaceable Superlift counterweight. For this purpose, a frame element is articulated at the rear end of the superstructure, which can be supported on the floor at the end arranged liftable feet. On this frame element, the superlift counterweight can be moved continuously to generate the desired counter-torque can. On the superstructure a buck is arranged, the top of which is connected to the head of the main boom via a variable length bracing. The tip of the buck is still connected via a fixed bracing with the end of the frame member. A disadvantage of this construction is that the projection is very large by the arrangement of the fixed frame part and the space required for this on the job site is not always given. In addition, the length of the frame element can only be changed by adding or removing segments, which means a set-up each time. Comparable as in the previously described known crane, the dead weight of the substructure can not be used to increase the stability in this proposed embodiment.
From GB 2151580 a crane is known which comprises a substructure and a superstructure rotatably mounted thereon. The superstructure is equipped with a hinged main boom and an attached mast, the tip of which is connected on the one hand via a variable length bracing with the head of the main boom and on the other hand via a brace with a counterweight. A separate superstructure weight is not provided. The distance of the counterweight to the superstructure of the crane can be changed continuously in a defined area via a movable in the vertical plane, arranged on the superstructure frame element.
Moreover, EP 0 368 463 A1 discloses a vehicle crane in which the counterweight can be displaced outwards on a telescoping displacement device. The free end of this telescopic sliding device can be supported by means of an extendable support foot on the ground. By a Seilabspannung that is variable by means of a hydraulic cylinder in length, the free end of the displacement device can be raised. The counterweight can be moved by means of a further hydraulic cylinder, which is also used to extend the telescopic displacement device, on the extended displacement device.

The object of the invention is a generic crane, in particular vehicle crane To specify with the while maintaining the rotation without retooling in easier Way an adaptation to the desired load moments under the given Site conditions is possible.

This object is based on the preamble in conjunction with the characterizing Characteristics of claim 1 solved. Advantageous developments are part of Dependent claims.

According to the teaching of the invention, the distance of the counterweight to the superstructure of Cranes on a movable in the vertical plane, arranged on the superstructure and frictionally associated frame member in a fixed area continuously variable, wherein the frame element with a means for Displacement of the resulting force between the gravitational force Counterweight force and the tension force generated by an attached load in the superstructure is provided.

The advantage of this arrangement is the fact that by the non-positive Connection of the frame element with the superstructure and through it arranged means the weight of the substructure to increase the Stability can be used. Depending on the direction of the resulting force between counterweight force and tension force, the agent once supports and once counteracting. For example, a situation is conceivable in the case of extended counterweight the attached load is not sufficient to the Counterweight to take off. The lifting of the counterweight is but Prerequisite that the crane can turn. In this case, the resultant is between clamping force and counterweight negative, as the direction Gravity counterweight force is greater than that generated by the load Anchoring force. In this simplified approach, the Friction conditions in the deflection points and guying unaccounted for stay. The arranged on the frame part means is now activated in such a way that it by vertical lifting of the frame part an additional force in the direction Tensioning force and against the counterweight force generated so that the Counterweight lifts and thus the crane despite the low load attached becomes rotatable. In the opposite case can be arranged by the invention Medium with attached maximum load ensures the stability of the crane by adding an additional force in the direction of counterweight and against the Tensioning force is generated without the counterweight touches down.

The frame element can be parallel to the plane of the upper carriage in the vertical plane movable or alternatively be arranged pivotably at an end region. Preferably, the pivot axis intersects the axis of rotation of the upper carriage. The Frame member has a connected to the superstructure axially fixed Frame part and at least one parallel to the fixed frame part axially sliding frame part on. Preferably, the axially displaceable frame part arranged telescopically in the fixed frame part. The movement of the sliding frame part can, for example, a rack or over a spindle done. As advantageous, the arrangement of an axially acting Piston cylinder unit exposed, which is hinged to the fixed frame part.

The means for displacing the resultant force has at least one vertical acting piston-cylinder unit. For reasons of space and for better distribution The forces will each one on the right and left of the fixed frame part Piston-cylinder unit arranged hinged on the one hand with the fixed Frame part and hinged on the other hand connected to the superstructure.

To the proposed arrangement not only as a superlift, but also as To operate normal crane, the fixed frame part extends over the Anlenkstelle the vertically acting piston-cylinder unit addition and this area can be bolted to a supporting structure that supports the counterweight. For this purpose points this area of the fixed frame part a collar-like stiffening and a rolling track for the counterweight receiving structure on.

To increase the load are on to the sliding frame part connected supporting structure additional counterweights can be arranged and with the supporting structure lockable. For safety reasons, the structure must be close to the ground reaching support feet are arranged. To facilitate the transport and the Handling these support legs are folded out on the structure arranged. The Additional counterweight is preferably in single, frame having Stackable. Each frame is connectable with at least four wheels, so that every single stack can be moved. This arrangement has the advantage that the additional counterweight can be easily transported to the job site. In addition, the support legs can be omitted on the structure for the counterweight, as the Wheels take over this function. In addition, in Superliftbetrieb the Counterweight including additional counterweight retracted, even if the attached load is not sufficient to take off. Is after retracting the Counterweight torque lowered accordingly, can with the attached load the Counterweight lifted and solved the additional counterweights from the structure become.

With the proposed overall construction is on the one hand a normal crane operation possible, with the inserted counterweight the function of a known Superstructure counterweight takes over. The projecting length of the fixed Frame part is chosen so that after displacement of the counterweight on the End of the fixed frame part, the rear stability still given is. This has the advantage that without retooling to the counterweight receiving structure additional counterweights can be arranged and bolted. The can on the one hand by pivoting the crane or in vehicle cranes by Be carried away. The lifting of this total counterweight, d. H. Counterweight plus additional counterweights is done by attaching a corresponding load, so that the crane can turn. By further moving the sliding frame part, the load torque can be increased. There the displaceable frame part is continuously displaceable, can at appropriate site conditions the radius adjusted to match become. The minimum radius is given by design. at Offset of the counterweight to the rear, a medium radius is adjustable until the point of the rear stationary torque is reached. The maximum radius gives on the one hand by the maximum displacement of the movable Frame part and on the other by the total ballast receiving Overall design. According to a first embodiment, the tip of the mast is via a length-adjustable bracing by means of a hinged support bracket connected to the counterweight. In this arrangement, both move the Mast as well as the length adjustable bracing between mast and Counterweight on the one hand and mast and main boom on the other hand corresponding for shifting the counterweight. This requires appropriate control, to the axial displacement of the counterweight with the pivoting movement of the Match mastes to each other. To reduce this effort is alternative suggested that the top of the mast be fixed to the mast Counterweight and a length-adjustable bracing by means of a articulated support bracket with the fixed frame part of the frame element connect to. In this arrangement, the tip of the trestle is over a fixed Lashing connected to the structure of the counterweight. This has the advantage that in superlift operation only the fixed bracing between mast and counterweight is effective. The shifting of the counterweight changing length of the firm bracing between the top of the mast and the structure of the Counterweight is negligible compared to the amount of upright Mastes and taking into account the shift of the counterweight in the Superlift operation just a few meters. When changing to normal operation is the fixed Lashing disassembled and only the variable length bracing is effective. In order to realize both variants, the lower end portion of the fork-like trained support bracket for receiving a length-variable bracing changeable winch in connection with a pulley optionally to the Counterweight receiving structure or on the fixed frame part of the Frame element articulated.

The advantages mentioned can be summarized in that the Ease of use is greatly improved, from normal operation to the highest counter-torque generating superlift operation all intermediate states in easy to set without retooling, taking into account the on the place of employment given space conditions.

In the drawing, the inventively designed crane is explained in detail using an exemplary embodiment. Show it

Fig. 1: in a side view of an inventively designed crane in the state "normal operation",
Fig. 2: as in FIG. 1, but in superlift operation,
Fig. 3: like Figure 2, the border areas of the superlift operation,
Fig. 4: like Figure 1, but as a single crane without mast,
Fig. 5a: a half-page top view without main boom and mast,
Fig. 5b: a section in the direction BB in Figure 5a,
Fig. 5c: a section in the direction AA in Figure 5b,
Fig. 5d: a view in the direction X in Figure 5b and
Fig. 6: a piston-cylinder unit for shifting the resultant force
Fig. 7: like Figure 2, but with a different type of bracing.

The illustrated in Figures 1 - 3 according to the invention formed crane consists of a substructure, here in the form of a crawler chassis 1 and a rotatably mounted thereon 2nd At the front end of the upper carriage 2, a main boom 3 is articulated by means of a hinge 4. Likewise, a mast 5 is articulated by means of a joint 6 in this area. The tip 7 of the mast 5 is connected to the head 8 of the main boom 3 via a length-adjustable bracing 9. On the other hand, the tip 7 of the mast 5 is connected via a length-adjustable bracing 10 with a counterweight 11. The connection of the bracing 10 with the counterweight 11 via a fork-like support bracket 22, 22 '(Figure 5c), between which a the length of the bracing 10 changing wind 24 is arranged. According to the invention, a box-like design fixed frame part 12 is arranged on the upper carriage 2, which is pivotally connected via two bearing blocks 13, 13 '(Figure 5a) non-positively connected to the superstructure 2. In this case, the pivot axis 25 intersects the axis of rotation 14 of the upper carriage 2. As shown in Figure 2, an axially displaceable frame member 15 is arranged in the axially fixed frame member 12 telescopically. In the rear end region of the fixed frame part 15, the resulting force between the counterweight and clamping force in the superstructure 2 displacing means is arranged. In this embodiment, the means consists of two right and left next to the fixed frame member 12 arranged piston-cylinder units 16, 16 '(Figure 5c). The fixed frame part 12 extends beyond the articulation point of the piston-cylinder units 16, 16 'and has for this area 20 collar-like stiffeners 17, 17' and a rolling track 18, 18 '. The latter feature serves to be able to move the supporting structure 19 receiving the counterweight 11 onto the stationary frame part 12 (see FIG. 1). In the state shown in Figure 1, the crane is in normal operation, wherein the pushed onto the overhanging portion 20 counterweight 11 assumes the function of a known Oberwagengegengewichtes. In this position, the minimum radius R _{min of} the center of gravity of the counterweight 11 results with respect to the axis of rotation 14 of the superstructure 2. For a specific design of the crane, this value is for example 7 meters.

FIG. 2 shows the same crane as in FIG. 1, but in superlift operation. In contrast to Figure 1, an additional counterweight 21 is attached to the structure 19. As can be seen in Figure 5d, the additional counterweight 21 may be divided into individual stacks, each stack is provided with a frame receiving the individual weights. The supporting structure 19 is provided with supporting feet 26 - 26 "', whose support plates can be extended to the ground.The displaceable frame part 15 is extended to maximum length, so that for the center of gravity of the total counterweight, ie counterweight 11 plus additional counterweight 21 a maximum radius R _max is obtained. For example is this radius R _max equal to 14 meters. thus, this total counterweight is held in suspension so that the crane can rotate the main arm 3, a load L is attached. in the example shown in this figure 2 state is the Radius of the load R _L = R _max .

FIG. 3 shows the boundary region of the superlift operation. The solid lines correspond to the maximum possible Superlift operation. The dashed lines correspond to the minimum possible superlift operation. In this position, a mean radius R of the upper carriage results _means the center of gravity of the total counterweight to the axis 14 2. With shouldered load L in this position, the total counterweight can be placed on the floor and the auxiliary counterweight 21 can be disconnected from the supporting structure 19th If the displaceable frame part 15 retracted even further, the state results as shown in Figure 1. By comparing the state according to the solid lines in contrast to the state according to the dashed lines, one can see the corresponding movement of the two braces 9, 10 and of the mast 5 to the movement of the displaceable frame part 15 recognize.

In Figure 4 it is shown that the proposed principle of a continuous Displacement of the counterweight 11 in conjunction with a supporting Means 16, 16 'is also for a single crane without mast advantageous. In contrast to Figure 1 is the fork-like support bracket 22, 22 'not on the structure 19 for the Counterweight 11, but on a arranged on the upper carriage 2 bearing block 23, 23 'articulated.

Figure 5b shows on the one hand the possibility of bolting the structure 19 with the axially displaceable frame part 15. For this purpose, a bracket 27 on the supporting structure arranged, which is arranged with a displaceable frame part 15 arranged block 28th is bolted. Furthermore, this illustration is the fixed to the frame part 12th refer to the hinged piston-cylinder unit 29 to the displaceable To move frame member 15 axially. With dashed lines is the maximum possible pivoting movement of the frame part, d. H. fixed frame part 12 and displaceable frame part 15 indicated.

In Figure 6 is a schematic diagram of the piston-cylinder unit 16 for the displacement of the resulting force between counterweight force and clamping force in the Upper carriage 2 shown. The piston-cylinder unit 16 consists of a Cylinder housing 30 and a piston 31 together with piston rod 32. At the bottom End of the cylinder housing 30, a web 33 is arranged with a bore 34. The Bore 34 is the point of articulation of the piston-cylinder unit 16 on the uppercarriage 2 (see FIG. 5b). The end of the piston rod 32 is formed as an eye 35 with a Bore 36. This is the pivot point of the piston-cylinder unit 16 at the fixed Frame part 12 (see Figure 5b). With the counterweight 11 removed, the piston takes 31 the middle position shown here. To keep the system stable in this situation is maintained, in the antechamber 37, a bias of, for example, 100kN abandoned, depending on the attached load L and the radius of the Counterweight 11 or additional counterweight 21 to the axis of rotation 14 of the Upper carriage 2 a forced withdrawal of the total counterweight required is in the main chamber 38 of the piston-cylinder unit 16 a corresponding pressure given up. For example, such a pressure can amount to a maximum of 3300 kN. The Pressure task causes a displacement of the piston 31 upwards. This is through a fully painted arrow 39 marked. By the mechanical Connection of the piston rod 32 with the fixed frame member 12 is through the displacement of the piston 31 up the fixed frame part 12 and Thus, the associated total counterweight shifted upwards. In 5b, this is indicated by dashed lines. As a rule, the Pressure task in the main chamber 38 directly by the crane operator by means of a Manual switch.

In the opposite case, with the maximum load attached, the bracing tries over the Coupling with the total counterweight and the displaceable frame part 15 to pivot the fixed frame part 12 upwards. This in turn causes a displacement of the piston 31 upwards. This movement can be limited be closed by closing the vestibule 37 and build up a pressure, the counteracts further upward movement. So that the piston-cylinder unit 16 is not overstressed, the vestibule 37 with a pressure relief valve (not here shown), which opens as soon as the pressure in the antechamber 37 a Maximum value has reached. For example, this maximum pressure could be 1200 kN be. When task test load the piston 31 is dashed in the upper shown position 31 'moved to the mechanical stop. The weaning the total counterweight takes place when reaching the piston 31 in the lower (shown here in dotted outline) end position 31 ".

Figure 7 shows the same crane as Figure 2 in superlift operation, but with a different type of bracing. In this embodiment, the tip of the mast 5 is connected via a fixed bracing 40 to the supporting structure 19 of the counterweight 11. In addition, the tip of the mast 5 is connected to the superstructure 2 via a length-adjustable bracing 10 by means of a support bracket 22 on a bearing block 23, 23 'arranged on the superstructure 2. The tip of the support bracket 22 is also connected via a fixed bracing 41 to the structure 19 of the counterweight 11. In the superlift operation shown here, only the fixed bracing 40 between the tip of the mast 5 and the structure 19 of the counterweight 11 is effective. The length-adjustable brace 10, however, depends limp. The resulting change in length of the fixed bracing 40 with axial displacement of the counterweight 11 of R _max to R _medium is negligible with respect to the height of the upright mast 5 and taking into account the displacement of the counterweight 11 only a few meters. With dashed lines is shown when the displacement of the counterweight 11 is carried on R _min and the counterweight 11 is usual Oberwagengegengewicht. Once R _medium is reached, the fixed guying 40 is released and the length guying 10 takes over the function. It then results in an arrangement comparable to Figure 1, as soon as the further displacement of the counterweight 11 has reached the end point R _min .

In this figure 7 is also the arrangement of wheels 42 on the stacks of the additional counterweight 21 shown. This greatly facilitates the transport and the handling of the additional counterweight 21st

position list

1: crawler track
2: superstructure
3: main boom
4: Joint for main boom
5: mast
6: Joint for mast
7: Top of the mast
8th: Head of the main boom
9: length-adjustable bracing
10: length-adjustable bracing
11: counterweight
12: fixed frame part
13: bearing block
14: Rotary axle uppercar
15: sliding frame part
16: Piston-cylinder unit
17: collar-like stiffening
18: rolling path
19: Structural
20: overhanging area of the fixed frame part
21: Extra counterweight
22: trestle
23: bearing block
24: winch
25: swivel axis
26: Support foot
27: hanger
28: buck
29: Piston-cylinder unit
30: cylinder housing
31: piston
32: piston rod
33: web
34: drilling
35: eye
36: drilling
37: antechamber
38: main chamber
39: movement arrow
40: firm bracing
41: firm bracing
42: bikes

Claims

A crane, in particular a vehicle crane, having a substructure and a superstructure (2) located in slewing manner thereon, which superstructure has a main jib (3) articulated thereto and a mast (5) (counter-jib) articulated thereto, the tip (7) of which is connected on one side via a guying system (9) of adjustable length to the top (8) of the main jib (3) and on the other side via a guying system (10) to a counterweight (11) without the provision of a separate superstructure counterweight, the distance of the counterweight (11) from the superstructure (2) of the crane being continuously variable within a set range via a frame element movable in the vertical plane which is arranged on the superstructure (2) and is frictionally connected thereto,
characterised in that
the frame element has an axially fixed frame part (12) connected to the superstructure (2) and
that the frame element is connected to a means for displacing the resulting force between the counterweight force acting in the direction of gravity and the guying force produced by a suspended load (L) in the superstructure (2), and that the means for displacing the resulting force has at least one vertically acting piston-cylinder unit (16, 16') which is articulated to the axially fixed frame part (12) and articulated to the superstructure (2).
A crane according to Claim 1, characterised in that the frame element has at least one frame part (15) which is axially displaceable parallel to the fixed frame part (12).
A crane according to Claim 2, characterised in that the displaceable frame part (15) is arranged telescopically in the fixed frame part (12).
A crane according to Claims 2 and 3, characterised in that the displaceable frame part (15) is connected to an axially-acting piston-cylinder unit (29) articulated to the fixed frame part (12).
A crane according to Claims 2 to 4, characterised in that an end region of the axially fixed frame part (12) is arranged vertically pivotably on the superstructure (2).
A crane according to Claim 5, characterised in that the pivot axis (25) of the frame part (12) intersects the axis of rotation (14) of the superstructure (2).
A crane according to Claim 6, characterised in that the means for displacing the resulting force is located on the other end region of the fixed frame part (12) spaced apart from the pivot axis (25).
A crane according to one of Claims 2 to 7, characterised in that the axially fixed frame part (12) extends beyond the point of articulation of the vertically acting piston-cylinder unit (16, 16') and this region (20) can be bolted to a supporting structure (19) which receives the counterweight (11).
A crane according to Claim 8, characterised in that the projecting region (20) of the fixed frame part (12) is provided with at least one collar-like bracing (17, 17') and a rolling track (18, 18') for the supporting structure (19) which receives the counterweight (11).
A crane according to one of Claims 8 to 9, characterised in that the end region of the axially displaceable frame part (15) can be bolted to the supporting structure (19) which receives the counterweight (11).
A crane according to one of Claims 8 to 10, characterised in that additional counterweights (21) can be arranged on the supporting structure (19) which receives the counterweight (11) and can be locked with the supporting structure (19) in order to increase the load.
A crane according to Claim 11, characterised in that the supporting structure (19) is provided with fold-out supporting feet (26 to 26") which extend into the vicinity of the ground.
A crane according to Claim 11, characterised in that the additional counterweight (21) can be divided into individual stacks having a frame.
A crane according to Claim 13, characterised in that each frame can be connected to at least four wheels (42).
A crane according to one of Claims 8 to 14, characterised in that the tip of the mast (5) is connected via a guying system (10) of adjustable length by means of an articulated support bar (22, 22') to the supporting structure (19) of the counterweight (11) and both the mast (5) and the guying systems (9, 10) of adjustable length between the mast (5) and the counterweight (11) on one side and the mast (5) and the main jib (3) on the other side move jointly corresponding to the displacement of the counterweight (11), the tip of the support bar (22, 22') having a connection to the supporting structure (19) of the counterweight via a fixed guying system (41).
A crane according to one of Claims 1 to 14, characterised in that the tip of the mast (5) is connected via a fixed guying system (40) to the counterweight (11) and via a guying system (10) of adjustable length by means of an articulated support bar (22, 22') to the fixed frame part (12) of the frame element, the tip of the support bar (22, 22') having a connection to the counterweight (11) via a fixed guying system (41).
A crane according to Claim 16, characterised in that in superlift operation only the fixed guying system (40) between the mast (5) and counterweight (11) is effective and upon changing to normal operation the fixed guying system (40) is dismantled and only the guying system (10) of adjustable length is effective.
A crane according to Claims 16 to 17, characterised in that the support bar (22, 22') is fork-shaped and that the lower end region of the support bar (22, 22'), to receive a winch (24) for changing the guying system (10) of adjustable length in combination with a block and pulley can be articulated alternatively to the supporting structure (19) which receives the counterweight (11) or to the superstructure (2) of the frame element.