1. Field of the Invention
The invention relates to a mobile harbor crane for the combined handling of containers and bulk materials, having an undercarriage and an upper carriage, which is mounted rotatably on the base frame of the undercarriage and on which a tower with a boom that can be pivoted about a horizontal axis is arranged.
2. Description of the Related Art
In the standard version, mobile harbor cranes of the type described above are designed for quays that allow relatively high axle loads of about 60 t/axle and surface loads of about 50 to 60 t/sq m under supporting plates provided.
For specific customers, the axle loads or surface loads can be reduced, if appropriate, by using additional axles and larger supporting plates.
In many parts of the world, however, the above measures on existing mobile harbor cranes are not technically feasible or adequate because the quays are extremely old. Even the construction of more modem quays, where standard concrete components used for building road bridges are generally employed, often allows only relatively low axle and surface loads.
It is the object of the present invention to design a mobile harbor crane for combined handling of containers and bulk materials in such a way that the mobile handling apparatus can be used with significantly reduced supporting loads for loading and unloading ships, even in seaports and inland harbors where the quays are not capable of taking the supporting loads of standard mobile harbor cranes.
To achieve the object, four support beams are connected pivotally to the base frame of the undercarriage, symmetrically to the longitudinal and transverse axes of the vehicle, in such a way that they can each be pivoted about vertical axes. The support beams are provided at their free ends with vertically acting leveling cylinders, by means of which the support beams are supported on the wheels of a plurality of traveling gear assemblies via balancers for uniform distribution of the supporting forces.
The mobile harbor crane according to the invention provides a new type of handling apparatus that is extremely mobile and flexible in application. There are no additional costs compared with a mobile harbor crane adapted specifically to customer requirements. Nevertheless, the balancer system ensures a uniform axle load matched to permitted quay loads and does so both in the transportation position and in the working position of the machine. Additional enlarged supporting plates are no longer required since the pedestal-like base frame of the undercarriage serves as a mounting for the four supporting beams, which transmit the supporting forces of the mobile harbor crane into the traveling gear assemblies via the balancers. At the same time, the traveling gear has a minimum support base during the transportation of the machine and a maximum support base when being used for work because the supporting beams can be pivoted into the working and transportation positions.
In a further refinement of the invention, it is envisaged that between the base frame and the balancer of each traveling gear assembly there is a coupling rod that forms a parallelogram linkage with the support beam and by means of which the traveling gear assembly can be adjusted parallel to the longitudinal axis of the vehicle in any pivoted position of the support beams. During and after the pivoting of the support beams, the coupling rods ensure that the wheels of all the traveling gear assemblies adopt a basic position in which they point in the same direction, namely in the direction of the longitudinal axis of the vehicle, irrespective of the size of the pivoting angle of the support beams.
To obtain stable conditions in the working position and in the transportation position, provision is made, according to a further feature of the invention, for the support beams to be capable of being fixed both in their extended working position and in their retracted transportation position by means of telescoping locking devices, which are arranged between the base frame and the free end of the support beams.
The support beams are adjusted with means belonging to the traveling gear itself since, according to another feature of the invention, it is proposed that to adjust the support beams between the transportation position and the working position, the axles of the traveling gear assemblies, which axles are pivotable through xc2x190xc2x0, can be adjusted under computer control and in a monitored manner on a common steering column, and the pivoting movements of the support beams can be performed by actuating the traveling gear drives. The position of the axles during this process is monitored by means of angular resolvers and pivoting takes place automatically in such a way that all the axles turn in the direction of the center of the machine (center of the rotary joint), for example. In this way, the support beams can be pivoted without additional hydraulic cylinders or similar devices.
The position of the axles (together with the wheels) is controlled by detectors of a control unit so that the alignment of all the wheels corresponds to the direction the crane will be moved. For example, if the crane moves straight ahead, all axles are oriented in parallel. To follow a curve, the axles are oriented so that the wheels follow an arc.
Since quays are often only relatively narrow and, after subtracting the necessary truck lane from the width of the quay, leave insufficient standing room to set up a standard-type mobile harbor crane with the required load capacity, the vehicular crane according to the invention offers, according to another feature of the invention, a free space in the longitudinal direction of the mobile harbor crane, between the traveling gear assemblies of the latter, to allow transportation vehicles to drive under the mobile harbor crane.
Because the mobile harbor crane according to the invention no longer requires separate support, the traveling gear that simultaneously serves as a support must be appropriately vibration-damped. To achieve this, the proposal is made, according to another feature of the invention, that the traveling gear assemblies of the mobile harbor crane have tires and, to damp vibration of the machine, the tires of the wheels are about 75% full of water. The vibration-damping effect of this measure is desired particularly when the machine is in the working position. Antifreeze is added to the water in the tires if required.
The invention provides a flexible and mobile handling apparatus that can be used cost-effectively and hence economically even on narrow quays where the subgrade is not very strong.
An exemplary embodiment of the invention is illustrated in the drawing and is described below.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.