This feeder is used in an underground coal mine. It is quite an asset to have one in any active working unit. Operating function: The shuttle car dumps it's load of coal into the hopper of this piece of equipment. The feeder breaks up any large coal, shale, rocks etc. and feeds it onto a beltline system and out of the mine. I was an shuttle car operater for 10 years and can attest to the value of this piece of equipment first hand. I also have a background in autocad/engineering and design and had fun designing this model.