Abstract: A cam frame assembly for a walking system includes a plurality of frame components. The frame components include an upper frame, a lower frame, a front guide frame, and a rear guide frame. At least one of the frame components includes a replaceable wear surface. The replaceable wear surface is an insert retained within a notch in the frame component.

Abstract: An excavator base is fabricated on-site by first erecting a substructure of beams on a concrete foundation. Large flat plates are placed on the substructure, welded together at their adjacent edges, and cut at a perimeter to form a bottom plate. A prefabricated center section is welded to the bottom plate. Upright diaphragms and edge plates are assembled on the bottom plate and welded to each other and to the bottom plate. Large flat plates are assembled on the top of the diaphragms, and edge plates, and are welded thereto and to each other. The welded plates are cut at a perimeter to complete a top plate. The base is then removed from the substructure. Alternately, the top plate can be formed on the substructure first and then removed and set aside for later use. Adjacent plates are held flat for welding using brackets and wedges.