Description  Four- united screw, discharging outlet fit with parallel united screw which consists of at least double parallel permutation of screw shaft, and screw paddles around shaft, united screw link has driving device. When material outflows from bin, start united screw directly, helix paddle rotates itself and stir material avoiding bridging, thrust material out of bin, then material transferred to outlet of bin via united screw to ensure the requirements of production. This crew can break material bridging quickly and tremendously increase transmission efficiency and speed of material outflow.