Heavy load handling

Heavy-load handling is not a standardised term with a fixed limit. It means handling loads beyond the range of hand-guided standard devices. Where that range ends depends on design and reach and is stated in the data sheet of the device concerned.

What decides is not weight alone but the load moment: load times distance from the axis of rotation. The same load that is guided without difficulty close to the column overloads the device at full reach.

There are three answers for heavy loads. The first is the crane – overhead travelling crane, slewing jib crane or gantry crane – with a lifting attachment that suits the load: lifting beam, tongs, C-hook, magnet, vacuum lifter. It lifts and travels but positions only as accurately as the swinging load allows.

The second is the special device: a manipulator designed for one particular heavy load and one particular movement – turning or joining, for instance. The third is floor-based equipment, from the lift table and heavy-duty trolley to the assembly trolley with lifting and tilting functions.

With the load, the forces that the building has to take grow too. A column needs a foundation that carries the overturning moment; a rail system on the ceiling needs proof that the ceiling can take the loads.

The hand-guided manipulator is built for guiding and positioning, within a limited working area and up to its rated capacity. The crane is built for lifting and travelling, across the whole bay and for large loads. The tasks overlap only in a narrow band.

The typical mistake is wanting one device to do both. Often the better solution is the combination: the crane brings the load to the station, and a suitable lifting attachment with a rotating or turning function does the fine work.