TOWER CRANE WITH ADJUSTABLE COUNTER-BALLAST

Abstract

The invention relates to a tower crane having a slewing platform, an adjustable boom articulated in a derricking manner on the slewing platform and counter-ballast mounted on the slewing platform, characterized in that an adjusting mechanism is provided that permits a positional change to the counter-ballast independent of the luffing angle of the adjustable boom.

Claims

1. A tower crane having a slewing platform, an adjustable boom articulated in a derricking manner on the slewing platform and a counter-ballast mounted on the slewing platform, wherein an adjusting mechanism is provided that permits a positional change to the counter-ballast independent of the luffing angle of the adjustable boom.

2. The tower crane according to claim 1, wherein a trolley, which receives the counter-ballast, is provided as the adjusting mechanism, which trolley is mounted relative to the crane slewing platform in a movable manner on same.

3. The tower crane according to claim 2, wherein the trolley can be moved in the horizontal direction relative to the slewing platform.

4. The tower crane according to claim 2, wherein the trolley can be moved by means of rope drive or a spindle drive.

5. The tower crane according to claim 1, wherein the counter-ballast is coupled to the adjustable boom by means of an articulated linkage, and by means of the adjusting mechanism the length of at least one of the rods of the linkage and/or the position of at least one hinge point of the linkage can be changed.

6. The tower crane according to claim 5, wherein the length of the at least one rod or the location of a hinge point can be set by means of an integral hydraulic cylinder or a spindle drive.

7. The tower crane according to claim 1, wherein the counter-ballast is coupled to the adjustable boom by means of a coupling rope, wherein by means of the adjusting mechanism the length of the coupling rope and/or the position of at least one of the deflecting rollers for the coupling rope can be changed.

8. The tower crane according to claim 7, wherein a hydraulic cylinder is provided as adjusting mechanism for changing the rope length or the position of a deflecting roller.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0015] Further properties of the disclosure are explained in more detail hereinafter on the basis of an exemplary embodiment shown in the drawings. Shown are in:

[0016] FIG. 1 a schematic representation of the inherent weight plot of movable parts of an upper crane depending on the boom angle;

[0017] FIG. 2 a first exemplary embodiment of the crane according to the disclosure with 4-joint kinematics

[0018] FIG. 3 a second exemplary embodiment of the crane with cable hoist system,

[0019] FIG. 4 a third exemplary embodiment of the tower crane with rigid coupling between boom and counter-boom

[0020] FIG. 5 a slightly modified embodiment of the tower crane according to FIG. 4 and

[0021] FIG. 6 another exemplary embodiment of the tower crane with a completely variable coupling between boom and counter-boom.

DETAILED DESCRIPTION

[0022] FIG. 2 shows an adjustable boom crane. The tower crane comprises a crane tower on the tip of which a slewing platform 1a is rotatably mounted by means of the slewing ring support 11 and the slewing ring 10. On the slewing platform 1a, the adjustable boom is mounted in a derricking manner about a horizontal axis. The luffing angle α can be set by means of the adjusting gear 8 and the luffing rope 9. For the lifting work, the lifting rope 7 extends from lifting gear 6 mounted on the slewing platform 1a to the boom tip.

[0023] The adjustable boom 2 is mechanically coupled by means of a 4-joint transmission to the counter-ballast 5, which consists of the swing arm formed by the adjustable boom 2, the coupling rod 3, the counter-ballast swing arm 4 and the connection device 13, which may be a hook. The two swing arms 2, 4 are hinged in a manner articulated via their articulation points C, D on the slewing platform 1a and on the A-frame 1b of the adjusting gear. The coupling rod 3 is connected in an articulated manner via pivot points A, B to the swing arms 2, 4. The connection device 13 can also be connected in an articulated manner to the swing arm 4 and to the ballast 5.

[0024] The displacement of the counter-ballast 5 in the event of a change to the angle α is carried out dependent on the lengths of the two swing arms 2, 4, the length of the coupling rod 3 and the position of the bearing points C, D of the two pivot arms 2, 4 on the crane structure 1a, 1b. The distance of the counter-ballast 5 from the crane axis of rotation 20 is a non-linear function of the boom angle α, which is specified by the adjusting gear 8.

[0025] The inherent weight moment of the displaceable counter-ballast 5 can now be carried out via a change to the inherent weight and via a change to the parameters of the 4-joint transmission. According to the disclosure, therefore, an adjusting mechanism is added to change the length of the coupling rod 3. This can be carried out through the integration of a hydraulic cylinder or spindle drive the actuation of which influences the length of the coupling rod 3. It is also conceivable that the coupling rod 3 is designed similarly to a tension lock so that the length of the coupling rod 3 can be manually changed. It is just as possible for the coupling rod to be provided with a plurality of bearing bores offset in the axial direction. The working length of the coupling rod can be changed through the appropriate choice of the bearing bore for assembly on the articulation and pivot points A, B.

[0026] An intervention in the kinematics is also possible by changing the length of the two swing arms 2, 4, e.g. by displacing the two bolting points A, B along the structural parts of the two components 2, 4 in the direction of the indicated arrows.

[0027] A second exemplary embodiment for the crane according to the disclosure is shown in FIG. 3. Identical parts here are shown with identical reference characters. Compared to the crane from FIG. 2, the mechanical coupling between adjustable boom 2 and counter-ballast 5 is achieved differently here. A trolley 40 is used here, to which the counterweight 5 is fastened and which is moved on an inclined plane by means of a pulley system 30a. The counter-ballast 5 is displaced dependent on the length of the boom swing arm 2, the length of the coupling rope 30a, the inclination of the travel path of the trolley 40 and the position of the bearing points of the deflecting rollers 30b, 30c as well as the position of the boom swing arm 2 on the frame 1a. The distance of the counter-ballast 5 from the crane axis of rotation 20 is a non-linear function of the boom angle α, which is specified by the adjusting gear 8.

[0028] The inherent weight moment of the displaceable counter-ballast 5 can be carried out via a change to the inherent weight and via a change to the parameters of the pulley system 30a. This can be done by changing the length of the coupling rope 30a. A corresponding adjusting mechanism, for example a hydraulic cylinder, can change the rope length while the crane is in operation.

[0029] An intervention in the kinematics and thus a change to the counter-ballast position can however also be carried out by displacing the bolting point A of the coupling rope 30 with the boom swing arm 2 along the structural parts of the boom 2 in the direction of the suggested arrows. This could also be carried out in an automated manner by means of a suitable adjusting mechanism.

[0030] Also conceivable is a displacement of the position of the deflecting roller 30b along the structural parts of the A-frame 1b in the direction of the suggested arrows or a displacement of the position of the deflecting roller 30c along the structural parts of the slewing platform 1a. The displacement of the deflecting rollers can also be implemented by means of a suitable adjusting mechanism, for example by means of a hydraulic cylinder.

[0031] A third embodiment can be taken from FIG. 4. On this crane, an adjusting cylinder 8a is used to change the angle α of the adjustable boom 2. The adjustable boom 2 is mounted not on the slewing platform 1a, but rather on the A-frame 1b. With this solution, a rigid coupling between counter-ballast 5 and boom 2 is furthermore used. A movable swing arm 4 is used, to which the counterweight 5 is fastened and which can be adjusted by means of a coupling rod 3. The rotation point of the swing arm 4 is the joint A. The pivot points of the coupling rod 3 are labelled B, C. The movement is relative to the boom 2 (not to the frame (1b)). The distance of the counter-ballast 5 from the crane axis of rotation 20 is a function of the boom angle α which is specified by the stroke of the adjusting cylinder 8a.

[0032] The inherent weight moment of the displaceable counter-ballast 5 can be carried out by changing the inherent weight and by changing the length of the coupling rod 3, similar to that proposed in the solution of FIG. 2. Specifically, the length of the coupling rod 3 can be set by means of an integral hydraulic cylinder or spindle drive. A manual change to the coupling rod length is also conceivable if this is designed in a similar manner to a tension lock or is provided with a plurality of bearing bores offset in the axial direction.

[0033] Particularly on the crane structure shown in FIG. 4, it makes sense to change the length of the coupling rod 3 during the switch to the out-of-operation state. On adjustable boom cranes, the boom 2 is brought into a relatively steeply pitched position (α=ca. 70°) during switching to non-operation. As a result, in this solution the counter-ballast 5 moves relatively close to the crane axis of rotation 20 and as a result can no longer develop an all too great inherent weight moment. However, this would be helpful to counter the out-of-operation wind load with a moment in the event of an inflow from behind.

[0034] A variation on this solution is shown in FIG. 5. In this variant, the coupling rod 3 is divided into two partial components 3a, 3b. The coupling and corresponding movement of the counter-ballast 5 is adapted to the movement of the boom 2 by means of a transmission 3c in an appropriate ratio. To obtain the necessary relative movement, the coupling rod 3a is connected no longer to the boom 2 but to the frame 1b. The pivot points of the swing arms 2, 4 is labelled A. The hinge point of the coupling rod 3a is labelled B and the hinge point of the coupling rod 3b is labelled C. The pivot points C, D also represent the pivot points of the adjusting cylinder 8a.

[0035] The above solutions are characterised in that the movement of the counter-ballast 5 is mechanically coupled to the movement of the boom 2. If it is possible to omit the load-relieving of the luffing drive, the counter-ballast 5 can, according to an embodiment of the disclosure, also be directly displaced by means of a separate drive-based adjusting mechanism. The optimisation problem is thus only limited to minimising the tower load.

[0036] To keep the load for this drive and the energy requirement associated therewith low, the counterweight 5 should be moved as horizontally as possible. This can be achieved with a driven trolley 40 (see FIG. 6) on which the counterweight 5 is fastened and which is moved e.g. by means of a rope drive comprising the rope 41d and the required rollers 41a, 41b, 41c. Alternatively, a spindle drive could also be used. By means of the rope drive, the trolley 40 and thus the counterweight 5 can be displaced horizontally on the slewing platform 1a, as a result of which the distance of the counter-ballast 5 to the crane axis of rotation 20 can be set completely independently of the angle α.

[0037] The advantages of this solution may include one or more of the following: [0038] the position of the counter-ballast 5 in the state “crane in operation” would be independent of the position in the “out-of-operation setting” [0039] the position of the counter-ballast 5 in the state “crane in operation” would be adjustable in any relationship to the boom angle α and [0040] the position of the counter-ballast 5 could be optimally and individually adapted to any boom length.