Abstract: A rotary cutter assembly has a spindle journaled by a bearing assembly. A cutter mounting member is fixed to the spindle for rotation therewith and has an outermost annular skirt that flares radially outwardly and downwardly to a lowermost peripheral edge. The bearing housing that supports the bearing has an upstanding rib that surrounds the lower peripheral edge of the mounting member and projects upwardly beyond the same for a short distance. This overlapping relationship between the rib and the lower skirt periphery prevents the ingress of foreign materials into close proximity with the bearing assembly to thereby prolong its useful life.