Traversing hoists – Having counterweight or counterbalancing means – Counterweight movable relative to load support
Reexamination Certificate
1999-09-10
2001-09-04
Brahan, Thomas J. (Department: 3652)
Traversing hoists
Having counterweight or counterbalancing means
Counterweight movable relative to load support
C212S279000
Reexamination Certificate
active
06283315
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention refers to a crane, preferably a derrick crane with a traveling chassis, a revolving superstructure mounted thereon that is connected with a ballast car by means of a shaft and on which a boom and a derrick, to which the ballast car is connected, are mounted in a luffing manner.
Cranes of this type are known, wherein the weight of the ballast car and the length of the shaft are, in principle, designed for the highest possible load. If lesser weights need to be lifted with these cranes, the maneuverability of the crane is impaired by the fact that the shaft is of a length that can, for example, prevent the rotation of the crane due to obstacles present.
SUMMARY OF THE INVENTION
The object of the invention therefor is to create a crane of the type described above in which the weight of the ballast car is better adjusted to the load to be lifted and that is easier to maneuver.
According to the invention, this object is solved in that the shaft consists of a telescoping beam that can be telescoped to a length corresponding to any given load or is longer than that.
If, for instance, the load is picked up with a relatively steep boom, the load moment produced by the ballast need also be only correspondingly small so that the load can be picked up with a short travel-out for the ballast car; this is of particular advantage when obstacles are present that make additional travel impossible for the ballast car. If the load travels out further during operation, for example, due to the luffing of the shaft, it can simultaneously be drawn back in during operation of the ballast car, to increase the load moment. Such use can be made of the ballast car if it is supported on the ground by means of its wheels, and even more simply if it is suspended due to the size of the load.
The telescoping beam forming the shaft can always be telescoped far enough that the ballast car produces adequate load moment. Based on the resolution of forces of the ballast car suspended from the derrick by means of a cable, only pressure forces and no torque is exerted, in principle, on the shaft.
A particular advantage of the crane according to the invention is that the lever arm acted upon by the counter-ballast produced by the ballast car, can also be changed during operation so that the load moment can always be adjusted to the suspended load and/or changes in the suspended load.
The beam can be telescoped out and in by hand or automatically by the crane operator. Controls are expediently provided that telescope the beam in and out depending on the load to be lifted or, during operation, according to the load moment of the crane.
According to another embodiment of the invention, provision is made for the wheels of the ballast car to be controllable.
According to a preferred embodiment, provision is made for a control that, depending on each extension position of the beam, aligns the axles of the wheels such that they cut the axis of rotation of the revolving structure. This embodiment ensures that the ballast car also easily rotates with the rotation of the revolving structure even if it is not suspended but rather supported on its wheels on the ground.
Expediently, the supporting frame of the ballast car is carried symmetrically to the transverse mid-plane of two sets of wheels. These wheel sets can be rotated by controllable drives, revolving through 360°. In this manner, the sets of wheels can be quickly and easily rotated into the desired position. When transporting the ballast car, the wheel sets can be rotated into a position in which they are under the chassis frame, parallel to the transverse mid-plane thereof.
According to another embodiment of the invention, provision is made for the supporting frame to have laterally-projecting supports in the mid-plane containing the beam. These supports stabilize the ballast car during its separate transportation on the bed of a transportation vehicle. Furthermore, these supports make it possible to move the shaft to the height of the revolving structure, through the corresponding extension and retraction thereof, so that it is easy to connect it to the revolving structure.
Expediently, the telescoping beam consists of pipes so that it can rotate around its longitudinal axis, if, for example, the path of travel of the chassis of the ballast car and the path of travel of the crane have different lateral inclinations.
To be able to transport the frame separately, it is designed to be connected to both the revolving structure and the ballast car. The couplings can, for example, consist of pin joints.
The invention described can be embodied not only by a ballast car, but also, for example, in a crane with a suspended ballast. The invention therefore refers to a crane, preferably a derrick crane, with a traveling chassis, a revolving superstructure mounted thereon, to which a boom and a derrick, on which a suspended ballast is suspended, are mounted in a luffing manner.
The object posed is solved, according to the invention, with such a crane in that the suspended ballast is support by a telescoping beam counter to the revolving structure.
Expediently, the beam can be extended and retracted by means of a control, preferably an automatic control in accordance with the angle of tilt of the boom.
Cranes of the claimed type are generally equipped with overload protection, where, in accordance with the current load, the permissible travel-out conditions are read off the load-carrying tables stored in the crane controls in ROMs. If automatic control of the travel-out conditions of the ballast car or suspended ballast is provided for the telescoping beam, the travel-out conditions are calculated by the crane controls from the load-carrying tables of the overload protection.
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patent: 4280627 (1981-07-01), Becker
patent: 4349115 (1982-09-01), Lampson
patent: 4614275 (1986-09-01), Zenno
patent: 4711358 (1987-12-01), Konishi
patent: 4716729 (1988-01-01), Kakeya
patent: 4995518 (1991-02-01), McGhie
patent: 0 048 076 (1982-03-01), None
Frommelt Uwe
Willim Hans-Dieter
Brahan Thomas J.
Dilworth & Barrese LLP.
Liebherr-Werk Ehingen GmbH
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