A spiral unloader or conveyors are used to extract crops on the silo base completely. These are specially designed equipment for extracting remnants at the silo bottom after grain is unloaded to a certain extent with its own flowing force. They can be manufactured from galvanized steel, painted steel or stainless steel as required by customers. The basic material is high grade steel. It conveys crops fast and smoothly without any problem. It is recommended for use twice or three times a year.