Stump cutter

A material reduction machine comprising:

• a frame;
• a primary driver supported by the frame;
• an arm assembly coupled to and extending from the frame, the arm assembly having a proximal end attached to the frame and a distal end opposite the proximal end;
• a bearing assembly including a bearing housing coupled to the arm assembly adjacent the distal end;
• a shaft rotatably coupled to the bearing assembly and having a shaft axis about which the shaft is configured to rotate;
• and
• a comminution wheel coupled to the shaft for rotation with the shaft about the shaft axis, the comminution wheel configured to be driven by a drive system and extending outward from the shaft in a radial direction that is perpendicular to the shaft axis;
• wherein a gap is defined between a portion of the shaft, the bearing assembly, and the comminution wheel;
• a guard plate attached to the bearing assembly or the arm assembly such that the guard plate does not rotate with the comminution wheel, the guard plate having an axial extent extending along the shaft axis and a radial extent extending radially relative to the shaft axis to fill a majority of the gap, wherein the axial extent and the radial extent lie in a plane.