Open-close type deck crane suitable for assembling mid-span steel beam cantilever of steel truss girder bridge

The invention relates to an opening and closing type deck crane suitable for assembling a mid-span steel beam cantilever of a steel truss girder bridge, belongs to the technical field of bridge construction equipment, and aims at a steel box stiffening variable cross-section through steel truss girder bridge which is of a box truss structure, and the two sides of the steel box stiffening variable cross-section through steel truss girder bridge are in a cantilever flange large spreading wing form. Due to the influence of the middle main truss, a bridge deck crane used for assembling a mid-span steel beam cantilever cannot adopt a transverse integrated bridge deck crane used when a conventional steel truss girder or a steel box girder bridge is used for erecting a mid-span section, and only the separated cranes on the two sides of the main truss can be adopted for hoisting the steel beam section; in other words, the two deck cranes lift mid-span steel beam sections on the two sides of the main truss through dou