I have no idea what this could be.
http://www.clevelandflats.org/images/Huletts%201990%205x7.jpg
That is a Hullet ore unloader.They were used to unload iron ore from the ore boats on the Great Lakes.The long aqrms would extend into the hold of the ship and scoop out the ore.The operator would ride in a small cabinon the unloader.They were used from sometime in the 20s or 30s and the last ones were retired in the 1980s I recall.