Crane main performance parameters indicators: starting weight. Lifting capacity: nominal weight of the crane can lift the material along with the spreader or attachment can be divided into the sum (such as grab, electromagnetic sucker, balance beam and other quality effective starting weight: Effective from the weight of the crane can lift the net mass of material crane main performance parameters indicators: Effective from the weight of the crane plate calibration used 20 tons of lifting capacity crane, usually refers to the rated capacity of the crane buy 20 tons crane, it shall be prominently represented in the apparent position of the crane structure. on. For the type of crane jib, the weight varies with the magnitude of its rated capacity, lifting its performance index is used to characterize the lifting moment. calibration on the plate is the maximum lifting capacity.