Frustoconical rotary cutter for digging trenches

Claim 1

For use on a draft vehicle, in combination, a rotary cutter for digging trenches and the like when drawn, a supporting arm on said vehicle including means for driving said rotary cutter and means for releasable attachment of said cutter in operative relation to the outer end of said arm, the improvement wherein said cutter comprises a forwardly-directed, disc-type frustoconical working surface and a rear peripheral sole, a plurality of chopping knives and alternately disposed ejector knives attached to the frustoconical working surface and extending substantially normal thereto and in helical distribution for enabling a stepped-down operation requiring minimum power, drive means operatively connected to said cutter for rotating said cutter from a power drive of the vehicle, said frustoconical working surface terminating at a generally flat forward surface free from said knives, said forward surface being operatively connected to said drive means, said drive means extending radially from the center of said forward surface, at least one gear means forming part of said drive means, and mean for adjusting the position of said working surface of said rotary cutter relative to the vehicle and the soil in which said working surface is being drawn by said vehicle.