a discharge apparatus for use in bins or hoppers in which a pluraity of rolls are disposed in a lower portion of the bin , and are so arranged to inhibit gravitational flow of material between the spaces defined by adjacent rolls . the rolls include knobs , plates , or the like extending outwardly therefrom , and the rolls may be arranged in a single row , or in multiple rows . when the rolls are rotated , material above the rolls is permitted to flow between the rolls and out of the bin or hopper . the rolls may be horizontal , or inclined , and may be variously shaped , including cylindrical , conical , or other geometrically complimentary shapes .