Crane with counter boom and method for erecting counter boom

Abstract

The present invention relates to a crane, particularly a mobile crane or crawler crane, comprising a main boom, a counter boom, and an erector platform arranged on the upper carriage of the crane, the erector platform being connected to a guying of the counter boom via a cable adjuster. At least one pressure prop is provided connected to the counter boom or the counter boom pivot shaft to temporarily receive the cable adjuster and / or the guying. The support point of the pressure prop is designed so that the cable adjuster or the guying can lift off from the pressure prop by itself at a specific counter boom erection angle.

Description

Technical Field

[0001] The present invention relates to a crane, particularly a mobile crane or a crawler crane, comprising a main boom, a counter boom, and an upright stand disposed on an upper carriage of the crane, wherein the upright stand is connected to a guying of the counter boom via a cable adjuster.

Background Art

[0002] Lattice mast large cranes generally consist of a main boom and a counter boom. The boom system is attached to an upper carriage rotatably mounted on a mobile lower carriage. To erect the crane, the main boom is assembled by the already assembled and erected counter boom in that the counter boom functions as a prop for the cable adjuster for erecting the main boom.

[0003] In previously known crane types, an adjustable upright stand attached to the upper carriage is required for the assembly of the counter boom. This is shown in the schematic crane representation of FIGS. 1a, 1b, which shows a crane comprising a lower carriage 11 and an upper carriage 12. The adjustable upright stand 4' is connected to the boom head of the counter boom 3 via a guying 6. The cable adjuster 5 is attached directly to the upper carriage 12 and is connected to the guying 6. By retracting the cable adjuster 5, the counter boom 3 can be erected. The reason for the selected structure is the possibility of operating the crane without the counter boom 3. The prerequisite for this is an adjustable upright stand 4'. The selected structure is used particularly in cranes with a lifting capacity of up to 1500 t.

Summary of the Invention

Problems to be Solved by the Invention

[0004] For large cranes with a lifting capacity of over 1500t, the use of a counter boom is obligatory. To erect the counter boom, various types of required erection gantries 4 have been developed for such cranes. The most widely used type is the fixed erection gantry 4 arranged on the upper carriage 12, which functions as a fixed point for the cable adjuster 5 and a pressure prop during the erection of the counter boom 3. This principle is shown in Figs. 2a, 2b. The solution using the adjustable erection gantry 4' as shown in Figs. 1a, 1b is not possible here due to the required high weight of such an erection gantry 4' and the space problem in the upper carriage.

[0005] This application seeks possible improvements to the existing solutions.

Means for Solving the Problem

[0006] This object is achieved by a crane having the features of claim 1, in particular a mobile crane or a crawler crane. Advantageous embodiments of the crane are the subject matter of the dependent claims. A novel and improved method for erecting the counter boom is provided by the features of claim 6. Advantageous embodiments of this method are the subject matter of the dependent method claims.

[0007] According to the present invention, it is proposed to reinforce a crane body comprising a cable adjuster and an erecting trestle arranged on an upper carriage by means of a counter boom, in particular an additional pressure prop connected in the vicinity of the counter boom foot or the pivot axis of the counter boom. The pressure prop is preferably connected in a pivotable manner, in particular pivotable about a horizontal axis. Also conceivable is a joint of the direct pressure prop on the pivot axis of the counter boom. In this case, the pivot axis of the pressure prop may be coaxial with the pivot axis of the counter boom. The cable adjuster is usually connected to the guying in order to be able to change the erection angle of the counter boom by operating the cable adjuster. The guying usually extends from the cable adjuster to the tip of the counter boom.

[0008] At least during the erection process, the pressure prop is in contact with the cable adjuster and / or the guying, and the pressure prop, in particular, receives the cable adjuster and / or the guying at its free end via a suitable bearing point. Thereby, the cable adjuster and / or the guying can be biased by the pressure prop to move away from the back of the counter boom.

[0009] Due to the compressive force additionally applied to the cable adjuster / guying by the pressure prop, the erected trestle or turntable used at the rear of the upper carriage can be of significantly smaller dimensions. The geometry for the lever arm and the generation of the required erection moment are significantly generated by the pressure prop employed. In contrast, according to the prior art solutions, the erected trestle has to protrude relatively far vertically from the upper carriage in order to generate at least a sufficient erection moment with respect to the counter boom.

[0010] Another advantage of the present invention is configured in the geometry of the invention formed by the upright stand, cable adjuster, pressure prop and guiding, in that a change in the angle of the counter boom leads to a minor change in the lever arm, which, in short, has a positive impact on the overall process, especially in the flat position.

[0011] Also, the size savings possible with the upright stand lead to an inevitable advantage. The changed geometry during power transmission leads to the fact that the retraction length of the cable adjuster required for the erection of the counter boom is reduced.

[0012] According to a preferred embodiment, the pressure prop is connected to the back of the counter boom. What has been found to be advantageous is the swivel attachment of the pressure prop at the back of the counter boom in the vicinity of its boom foot. This position of the pressure prop has an optimal influence on the lever arm that occurs during the erection of the counter boom.

[0013] Similarly, according to the present invention, the connection between the pressure prop and the cable adjuster or guiding is only temporary, i.e., the cable adjuster or counter boom guiding can lift itself off the pressure prop by itself. In particular, the cable adjuster / guiding is operably connected to the pressure prop only at the start of the counter boom erection process. From a specific erection angle of the counter boom, the cable adjuster / guiding lifts itself off the pressure prop by itself. A corresponding arresting point may be provided to prevent the pressure prop from falling after the cable adjuster has lifted off. The falling can occur in both directions.

[0014] The cable adjuster or guiding is placed on the appropriate bearing point of the pressure prop, which enables it to lift off at a specific upright angle of the counter boom. However, it is advantageous if the tension that generates the swiveling movement of the pressure prop can be applied to the pressure prop by the cable adjuster. This can be imagined to occur by corresponding restraining means such as a stopper in the vicinity of the guiding or bearing point.

[0015] The bearing point of the pressure prop is preferably suitable for receiving and bearing the roller shaft of the top block of the cable adjuster. Ideally, the operation of the cable pulley is not impaired, thereby enabling the cable adjuster to operate without restrictions. For example, the bearing point enables the roller shaft to lift in the longitudinal direction of the pressure prop. However, it is conceivable that the relative movement of the top block in the lateral direction with respect to the longitudinal axis of the pressure prop is hindered due to the corresponding side stopper. Similarly, it is imaginable that the top block of the cable adjuster can be temporarily fixed to the pressure prop by a locking mechanism.

[0016] The erected stand used may be configured as a particularly triangular erected stand fixed to the upper carriage. Preferably, the erected stand is attached to the rear end of the upper carriage. In addition to the cable adjuster, the erected stand can also receive the retracting mechanism of the cable adjuster.

[0017] According to an advantageous embodiment of the crane, the crane is configured as a mobile crane or a crawler crane. Here, a suitable lattice boom is adopted as the counter boom. For example, the main boom is a lattice boom.

[0018] In addition to the crane according to the present invention, the present invention also relates to a method for erecting the counter boom of the crane according to the present invention. According to the present invention, a cable adjuster or guying is proposed for a method such that, at the start of the erection process of the counter boom, it is received at a small erection angle of the counter boom by the bearing point of the pressure prop, since the cable adjuster or guying is biased by the pressure prop to move away from the back of the counter boom. At a predetermined erection angle of the counter boom, the cable adjuster / guying means itself means lifting off from the pressure prop.

[0019] The wide-ranging advantages obtained by the implementation of this method have already been described above with reference to the crane. Therefore, in order to avoid repetition, further embodiments are omitted at this point.

[0020] For the implementation of the method, it is first proposed as a first step to attach the counter boom to the upper carriage together with the pressure prop already connected thereto. In the next step, the pressure prop can be provided to fold forward in the direction of the counter boom tip. In a further step, the cable adjuster is also pulled forward in order to place the cable adjuster at the end at the bearing point of the pressure prop provided for this purpose. At the same time, the guying of the counter boom is connected to the cable adjuster, in particular bolted.

[0021] In the next step, it may be provided that the pressure prop is first erected to a specific angle by retracting the retraction mechanism of the cable adjuster. This is achieved by corresponding stoppers or restraining means in the vicinity of the bearing point, which provide the tension transmission from the cable adjuster to the pressure prop. At the same time, the tension leads to the tensioning of the counter boom guying.

[0022] In the next step, the counter boom can be raised by further retracting the cable adjuster's retraction mechanism, i.e., to a specific desired erection angle. From a specific counter boom angle, the cable adjuster automatically disengages from the pressure prop. During further crane operations, the pressure prop is no longer required. The counter boom is guided and luffable independently by the guiding and the cable adjuster. The counter boom is placed in the reverse order. Due to the above-mentioned detent points, the pressure prop remains in a position where the pressure prop can pick up the top block again at a specific arrangement angle.

[0023] Further advantages and features of the present invention will be explained in detail below with reference to the exemplary embodiments shown in the drawings.

Brief Description of the Drawings

[0024]

Fig. 1a

Fig. 1b

Fig. 2a

Fig. 2b

Fig. 3a

Fig. 3b

Fig. 3c

Fig. 3d

Fig. 3e

Fig. 3f

Fig. 4

Fig. 5a

Fig. 5b

Fig. 5c

Fig. 5d

Fig. 5e

Fig. 5f

Fig. 5g

Fig. 5h

Mode for Carrying Out the Invention

[0025] The crane structure according to the prior art, as shown in FIGS. 1a, 1b, 2a, and 2b, has already been described in the introduction section. Therefore, repeated explanations are omitted.

[0026] The structure according to the present invention is shown in FIGS. 3 and 4. The individual crane components are most readily recognized in the large representation of FIG. 4, and the large crane shown therein includes a lower carriage 11 (here a crawler travel gear) and a turntable 12 rotatably disposed on the lower carriage. The derrick type counter boom 3 is connected to the turntable 12 so as to be able to rise and fall. Similarly, the main boom 13 is also attached to the turntable so as to be able to rise and fall and is configured as a lattice mast.

[0027] At the rear end of the upper carriage 12, an erection stand 40 is arranged, and the erection stand 40 is fixedly attached to the upper carriage 12 as a rigid structure. The erection stand 40 is substantially triangular. At the uppermost point of the erection stand 40, a cable adjuster 5 is attached. The length of the cable adjuster 5 can be set by a retraction mechanism 5a, and the retraction mechanism 5a is also attached to the erection stand 40.

[0028] The guying 6 composed of individual guy rods is directly bolted to the top block 51 of the cable adjuster 5. By operating the retraction mechanism 5a, that is, by retracting the cable, the length of the cable adjuster 5 is reduced, whereby the guying can be tightened, the length can be changed, and the derrick boom 3 can be raised and lowered.

[0029] The pressure prop 311 according to the present invention is attached to the articulated leg of the derrick boom 3 so as to be rotatable about a horizontal axis. At its free end, an appropriate bearing point 311a is provided for receiving the top block 51 and applying a compressive force to the pressure prop 311.

[0030] The assembly and placement process of the derrick boom 3 can be illustrated with reference to the crane states of FIGS. 3a to 3f shown in chronological order. In the first step as shown in FIG. 3a, the counter boom joint piece 31 of the derrick boom 3 is attached to the turntable 12. The pressure prop 311 is already pre-attached to the counter boom joint piece 31. The disassembly and placement process is performed in the reverse order (FIGS. 3f to 3a).

[0031] In the next method step as shown in FIG. 3b, the pressure prop 311 is folded forward in the direction of the derrick boom tip. At the same time, the cable adjuster 5 is extended by unwinding the retraction mechanism 5a, and the top block 51 is also pulled forward in the direction of the derrick boom tip, and its roller shaft can be received by the bearing point 311a of the pressure prop. At the same time, the top block 51 is bolted to the guiding 6 of the derrick boom 3.

[0032] In the next method step as shown in FIG. 3c, the pressure prop 311 is erected by operating the retraction mechanism of the cable adjuster 5, and in particular, is pivoted backward in the direction of the erection stand 40. As a result, the guiding 6 of the derrick boom 3 is simultaneously tightened.

[0033] By further pulling in the strands of the cable adjuster 5 by the pulling-in mechanism 5a, the counter boom 3 can be raised as shown in Fig. 3d. Fig. 3a also schematically shows the raising angle of the derrick boom 3. The top block 51 of the cable adjuster 5 is positioned exactly at the bearing point 311a on the pressure prop 311, but has already started to lift off from the pressure prop 311. By further raising the derrick boom 3 to the position shown in Fig. 3e, the cable adjuster 5 completely lifts off from the pressure prop 311. The pressure prop 311 no longer functions from this state and remains in a predetermined position by a restraining device. For completeness, Fig. 3f also shows the desired end position of the derrick boom 3. This representation is, in principle, the same as the representation in Fig. 4 (except that the latter already shows the attached main boom 13). A known fallback press 312 for the counter boom 3 is still required and is shown in Figs. 3a - 3f and 4.

[0034] Therefore, during normal crane operation, neither the cable adjuster 5 nor the guying 6 contacts the pressure prop 311. Therefore, the pressure prop remains non-functional throughout the crane operation and is only required to raise the derrick boom 3.

[0035] In FIGS. 5a to 5h, for visualizing the advantages of the present invention, a schematic representation of the crane according to the present invention is compared with the crane structure of the prior art. The comparison in FIGS. 5a and 5b serves to show the ratio between the upright frame 4 according to the prior art (FIG. 5a) and the upright frame 40 according to the present invention (FIG. 5b). Clearly visible is the distinct difference in height between both upright frames 4, 40. The upright frame 40 is a simpler and smaller, fixed upright frame 40. This results in a distinct weight and cost savings during manufacturing. In the prior art (FIG. 5a), in order to obtain a sufficient lever arm H during the erection of the counter boom 3, it is necessary to design the upright frame 40 relatively large and high. By using the pressure prop 311 (FIG. 5b) described here, the upright frame 40 at the rear of the turntable can be designed distinctly smaller.

[0036] In the crane according to the present invention, a distinctly smaller length L is simultaneously required for the cable length in the retraction mechanism of the cable adjuster 5. A direct comparison between the fixed upright frame 4 of the conventional structure (FIG. 5d) and the crane body of the present invention described here (FIG. 5c) shows that the cable length L required for the erection by the retraction mechanism 5a is shorter than in FIG. 5d. The shorter length L is achieved by the reeving of the cable for the cable adjuster 5. The shorter length L is due to the smaller upright frame 40 in the solution described here (FIG. 5c), which leads to a more favorable erection geometry.

[0037] Furthermore, the solution according to the present invention also provides a more favorable lever arm H' for the cable adjuster 5 (see FIG. 5e) when the counter boom 3 is erected (a change in the angle of the counter boom 3 leads to a smaller change in the lever arm). When the counter boom 3 according to the conventional crane in FIG. 5f is further lowered, for example, a change in angle of 1 degree leads to a greater reduction in the lever arm than in the case of the crane according to the present invention as shown in FIG. 5e. The relevant lever arm H' here is the vertical distance between the center line of the cable adjuster 5 and the counter boom joint point.

[0038] Furthermore, in the crane according to the present invention (Figure 5g), slightly better geometry can be obtained compared to the conventional crane (Figure 5h). Due to the shorter fixed mast 40, better lever arms H’’ can be obtained at some counter-boom positions as shown in Figure 5g compared to Figure 5h. In the representation of Figure 5g, the lever arm H’’ is slightly longer than the lever arm H’’ of Figure 5h with the same boom length and upper carriage length. That is, a larger moment can be generated with the same force in the guying strand 6. The relevant lever arm H’’ here is the vertical distance between the boom guying 6 and the counter-boom joint point.

Claims

1. A crane comprising a main boom, a counter boom, and an upright stand disposed on an upper carriage of the crane, wherein the upright stand is connected to a guiding of the counter boom via a cable adjuster, at least one pressure prop is provided which is connected to the counter boom or a pivot axis of the counter boom to temporarily receive the cable adjuster and / or the guiding, and a receiving point of the pressure prop is designed such that the cable adjuster or the guiding can lift off from the pressure prop at a specific upright angle of the counter boom by itself, the pressure prop is pivotally attached to the back of the counter boom in the vicinity of its boom foot or its pivot axis. The crane is characterized by this.

2. The crane according to claim 1, wherein the pressure prop is pivotally attached to the back of the counter boom in the vicinity of its boom foot or its pivot axis so as to be pivotable about a horizontal axis.

3. The bearing point of the pressure prop for receiving the cable adjuster receives a restraining device or a stopper for the cable adjuster / the guiding in order to be able to apply a tension that generates a pivoting movement of the pressure prop with respect to the pressure prop by the cable adjuster. The crane according to claim 1 or 2 is characterized by this.

4. The roller shaft of the top block of the cable adjuster is received by the bearing point of the pressure prop, and optionally, a locking mechanism is provided for temporary fixation of the roller shaft at the bearing point. The crane according to any one of claims 1 to 3 is characterized by this.

5. The upright stand is designed as a fixed upright stand in the upper carriage and is attached to a rear end portion of the upper carriage, and the upright stand receives a winding winch of the cable adjuster. The crane according to any one of claims 1 to 4 is characterized by this.

6. The crane according to any one of claims 1 to 5, wherein the counter boom is a lattice boom. **Claim 7**: A crane comprising a main boom, a counter boom, and an upright stand disposed on an upper carriage of the crane, wherein the upright stand is connected to a guiding of the counter boom via a cable adjuster. At least one pressure prop is provided which is connected to the counter boom or a swivel axis of the counter boom for temporarily receiving the cable adjuster and / or the guiding, and a receiving point of the pressure prop is designed such that the cable adjuster or the guiding can lift off from the pressure prop at a specific upright angle of the counter boom by itself, preparing a crane. The cable adjuster or the guiding is received at a small upright angle of the counter boom by a bearing point of the pressure prop at the start of an upright process of the counter boom, because the cable adjuster or the guiding is biased to move away from a back portion of the counter boom by the pressure prop, and the cable adjuster or the guiding lifts off from the pressure prop at a predetermined upright angle of the counter boom by itself. A method for uprighting a counter boom of a crane, characterized by the above. **Claim 8** In a first step, the counter boom is attached to the upper carriage together with the pressure prop, according to the method of Claim 7. **Claim 9** After assembly of the counter boom, the pressure prop is folded forward in a direction of a tip of the counter boom, the cable adjuster is connected to the guiding, and the pressure prop is placed at the bearing point, according to the method of Claim 8. **Claim 10** By retracting a retraction mechanism of the cable adjuster, the pressure prop is erected and the guiding is tensioned, according to the method of Claim 9. **Claim 11** The counter boom is erected by retracting the retraction mechanism of the cable adjuster, according to the method according to any one of Claims 7 to 10. **Claim 12** The pressure prop is connected to the cable adjuster or the guiding only for erecting the counter boom, according to the method according to any one of Claims 7 to 11.

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