Innokran selected crane components from Stahl CraneSystems to build two magnetic cranes for steel trader Dewald Stahlhandler.
The magnetic cranes are based in the company’s storage hall in the Swabian town of Pleidelsheim Dewald, Germany. With these machines Dewald can lift individual pieces up to 14t and offer larger diameters of rod steel.
Innokran built a 16t magnetic crane with two 8t wire rope hoists from Stahl CraneSystems’ SH series and a magnetic lifting beam from Scheffer.
Apart from long rods, offcuts and short rods also need to be transported, that is the reason behind the crane designer choosing a two-part lifting beam that can be inclined.
“In this way there are either all four magnets available for long objects or just two at different heights with which short steel rods can be lifted optimally,” Stahl CraneSystems said.
The two hoists on the crane normally run in tandem mode, in which the crane operator places the magnetic lifting beam down on the steel by radio remote control, activates the four electromagnets with a button, and the load is held safely by the crane.
If short parts need to be picked up, the two parts of the lifting beam can be moved to different heights with the help of the wire rope hoists and their magnets can be switched separately of each other. In this way it is possible to also transport short steel rods.
“Frequency inverters at the hoist and travel motors see to gentle, soft movements. Thanks to them it is possible to put down heavy steel rods precisely. The controlled starting and breaking reduces the time-consuming swaying of the load and also reduces the effects on the crane runway and thus the hall construction,” Stahl CraneSystems said.
Apart from the 16t magnet crane, a second newly-installed crane with two SH wire rope hoists with a lifting capacity of 6.3t each and crane components from STAHL CraneSystems also runs in the hall. This 12.5t overhead crane also serves to move the long steel rods.
Its main task is, however, to lift cut steel slices out of the saw. The slices are placed on pallets and then loaded on to trucks by forklift. A special single magnet that is hung from one of the wire rope hoists is used for fastening. The power connection needed for this is located at the load hook. Since the steel slices stand upright after cutting, but need to be transported lying down, the special tip magnet offers the possibility of turning the load in the air.
One of the requirements for the design of the crane was to make best-possible use of the height of the hall in order to achieve the greatest-possible height of lift. The criterion was to be able to, in uppermost hook position – including the headroom of the magnetic lifting beam and the diameter of the steel rod – unload rods with the greatest possible diameter over the board walls of 40t articulated trucks, which are around 4m in height.
With a crane runway at 5.68m and a specified clearance of 6.89m, Innokran had no other alternative than to construct the crane as double girder overhead crane and to place the hoists above the crane bridge.
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