This method of unloading had to change when goods were no longer packaged in sacks, but transported and stored in bulk. Initially, to move a bulk cargo from ship to the warehouse containers were filled and lifted by crane. This is the basic principle used today in the form of a grab crane. Continuous discharge equipment was not developed at this time and this progressively evolved using various types of screw conveyors, chain and flight conveyors conveyor belts bucket elevators and finally pneumatic suction systems. Many characteristics set pneumatic suction systems apart from mechanical conveyor systems. Since this field has involved the development of special techniques, it is intended to explain them briefly below and then to examine general operational and technological aspects.
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