QDY overhead crane  is a kind of casting workshop crane and it is one of the main equipments in the continuous casting technology of steelmaking. It is mainly used in BOF bay, EAF bay and CCP bay in steel smelting shop to pour melted iron from additive bay of converter to converter; lifting molten steel from refining bay to refining furnace or lift molten steel from molten steel bay to ladle turret of continuous casting machine. The working duty of the cast crane complete machine is A7. The overall structure of foundry crane has the following forms: two girders and two rail, four girders and four rails, and four girders and six rails, etc. The form of two girders and two rails, four girders and four rails, are mainly used for middle and large-tonnage foundry crane; the form of four-girders and six-rails and two trolleys is mainly used for extra large-tonnage foundry crane.