Abstract: A hammer mill apparatus for comminuting materials such as wood, branches, twigs, leaves, grasses, hay, and the like, features a reciprocating batch feeder for feeding the materials to be comminuted into a rotary grinder. Adjustable and spring biased feed drum and metering roller meters the material into the hammer mill. The positions of a series of adjustable curved grinding teeth changes the sizes of the comminuted particles.

Abstract: A mini-sized hammer mill apparatus is adaptable for both rotatable tub feeding of hay, fodder, feed grains, and the like, as well as for chute feeding of wood and debris for comminution. A number of features optimize the mini size for effective, reliable, and smooth operation by small horsepower tractors, including: side feed tangentially out of a cylindrical hopper under a rotatable tub into the periphery of a large diameter, narrow rotor, or through a chute with tensioned roller feeder; radially adjustable grinding and metering finger/grate bar combination, secondary grinding fingers and breaker bar, self-sharpening hook-like pointed hammers, rotatable tub mounting structure, and enhanced energy dissipating, down-sized cyclone with reverse-louvered pressure dissipators.