Abstract: An upgraded quay crane system and an operation process, wherein a conventional quay crane girder is upgraded into a double-trapezoid four-track girder (1). An upper trolley (2) travels on upper trolley running tracks (a16) on an inner side of the double-trapezoid four-track girder (1), a lower trolley (3) is suspended upside down on lower trolley running tracks (a8) on an outer side of the double-trapezoid four-track girder (1), and a container (5) hoisted by the upper trolley (2) via a hoist (4) is able to pass through the lower trolley (3). The present quay crane system improves on the conventional quay crane having a single operation trolley by adding one more operation trolley on the outer side of the original quay crane girder. The two trolleys are vertically disposed, and the space structure for the lower trolley is cleverly designed, such that the two trolleys can operate independently without interfering with each other.

Abstract: The invention is a novel lower-trolley system, comprising a lower trolley (3), a lower-trolley hoisting system, and a lower-trolley travelling system. The lower trolley (3), the lower-trolley hoisting system and the lower-trolley travelling system are all arranged on a quay crane; the lower-trolley hoisting system drives a hoist (14) of the lower trolley (3) to rise and fall, and the lower-trolley travelling system pulls the lower trolley (3) to make same travel in the direction of a double-trapezoid four-track girder (1) of the quay crane; and the lower trolley (3) is hung upside down on outer-side tracks (15) of the double-trapezoid four-track girder (1), and a container (12) hoisted by an upper trolley (2) can pass through the lower trolley (3).