Abstract: A chipper has a housing formed with an intake defining a feed direction, a hollow drum rotatable in the housing in a rotational sense about an axis transverse to the feed direction and formed with a plurality of angularly spaced, radially throughgoing, and axially elongated windows, and a respective blade fixed to the drum immediately downstream in the sense from each window. The blades have edges defining on rotation of the drum an orbit. A breaker plate secured in the housing defines with the orbit a gap narrowing toward the drum and is formed with a plurality of wedges extending generally in the direction, having sharp edges directed generally radially at the drum, and spaced radially from the drum. A motor rotates the drum in the sense and thereby presses material fed in the direction into the housing against the wedges to split the material with the wedges, then draw it into the gap, and then comminute it with the blades.