Patent ID: 8176662

Claim:
A digging system comprising: a machine having a machine frame, ground engaging propulsion elements coupled with the machine frame, and a motor mounted to the machine frame and having a motor output shaft; and an implement assembly including an elongate boom having a proximal boom end pivotably coupled with the machine frame, a distal boom end, and a drive system having a drive wheel coupled with the motor output shaft and being positioned adjacent the proximal boom end, and a guide wheel mounted to the distal boom end, the drive wheel defining a first axis of rotation and the guide wheel defining a second axis of rotation; the implement assembly further including a trenching mechanism having a plurality of drawing cutters coupled with an endless drive chain contacting and movable about each of the drive wheel and the guide wheel, and an undercutting mechanism mounted to the distal boom end and having a first rotating cutter projecting in a first axial direction from the distal boom end, and a second rotating cutter projecting in a second axial direction from the distal boom end; an elongate shaft extending through the guide wheel from a first axial side to a second axial side thereof, the elongate shaft being fixed to rotate with the guide wheel, and each of the first and second rotating cutters being fixed to rotate with the elongate shaft, such that moving the endless drive chain about the drive wheel rotates the first and second rotating cutters; the first axis of rotation and the second axis of rotation defining a plane, and the implement assembly further defining a compound projection profile in the plane, the compound projection profile including a proximal stem segment corresponding to the trenching mechanism, and a distal footing segment corresponding to the undercutting mechanism and adjoining the proximal stem segment; the proximal stem segment including a relatively narrow segment width defined by outboard edges of the drawing cutters, and the distal footing segment including a relatively broad segment width defined by outboard ends of the first and second rotating cutters; and wherein each of the first and second rotating cutters tapers in diameter from a narrower diameter at axially outward locations to a broader diameter at axially inward locations.