Abstract: A self-contained precision quill-feed unit is provided with a positive stop arrangement to control depth of tool feed. The stop position is adjustable from the exterior of the unit and the stop abutments associated with moving and stationary members are positioned in such manner that no yawing forces are imposed on the quill, drive shaft and spindle of the unit. Additionally, yawing forces generated by the mechanical resistance of a known type of hydraulic constant velocity control (CVC) cylinder are opposed by reaction forces associated with the anti-rotation linkage that prevents rotation of the quill. Together these features provide overall a machine in which quill, drive shaft and spindle deflection or yawing is minimized or prevented.

Abstract: A depth-of-cut bushing is mounted above a cutter-arm array to provide a cutting head mounted on a rotary lawn mower or mower/trimmer. The bushing is shaped so that it acts together with the cutter-arm array to accomplish control of the cutting action. This control enables chipping of stumps or roots at the low horsepowers available with lawn mowers or mower/trimmers.