Abstract: A lump breaker apparatus mounted to an airlock of an economizer ash hopper for breaking up ash clinkers accumulated on a grating disposed in the airlock to maintain the passage of ash through the grating of the airlock. The apparatus comprising a pneumatic cylinder having a rod extending therefrom with a ramming plate connected to a distal end thereof and slidably disposed on the grating of the airlock, a mounting assembly for mounting the cylinder to the airlock and a seal assembly for providing a slidable seal about the rod. The ramming plate reciprocally movable from a retracted position to an extended position along the grating to impact the ash clinkers on the grating of the airlock with sufficient force to fragment such ash clinkers and to permit the passage of some ash clinkers through the grating.