Abstract: A lump coal size sorting grate comprising parallel bars is provided with three spaced apart, parallel cleaning combs which can be individually activated to clean the sizing grid of lodged coal lumps in a predetermined sequence so that the entire sizing grid is never closed during a coal sorting operation. The cleaning combs are made of spaced, parallel bars which can be pivoted upwardly, between and through the bars of the sizing grate. An adaptive system which senses and responds to a clogged condition in the grate can be provided by sensing crusher motor current or, in the alternative, sensing grate bar deflection using strain gage transducers.