Clamshell power installed screw anchor

Abstract

A clamshell screw anchor is provided which is inexpensive to manufacture, installable in many types of soils including rocky and frozen soils, and is adaptable for use in various applications, such as supporting electric transmission poles. The screw anchor broadly includes a unitary body member, a core, and a helical load bearing element. The body member is stamped from a substantially flat piece of material, and presents a pair of opposed, elongated body segments depending from a line of symmetry. Each of the body segments includes a first end shaped to define a hub element having a C-shaped cross section, a second end shaped to define a lead point element, and a pair of longitudinally extending side edges. The body member is folded about the line of symmetry, and the body segments are secured together along the side edges so that the hub elements form a hub having an open, upper end, and a rectangular cross-sectional shape, and the lead point elements form a lead point having an earth-engaging tip. The core is positioned within the shell, and includes a first end adjacent to the first ends of the body segments, and an axially extending tapped bore formed in the first end. The core is attachable to elongated support rods used to support poles, towers, and the like. The helical load bearing element presents a leading edge, and a trailing edge adjacent to the open, upper end of the hub. The load bearing element facilitates installation of the anchor into the earth, and resists pulling and tensional forces exerted on the anchor once it is positioned.