Patent ID: 8182353

Claim:
A drive mechanism for a subterranean soil processing tool wherein a crane has a boom, a lead column and a rotary drive table, and Kelly bar sections are joined together on a vertical axis (A-A) and rotated around said (A-A) axis by said rotary drive table to advance said soil processing tool downwardly, each of said Kelly bar sections having a central region, an upper end and a lower end, and an upper tip and a lower tip, characterized by: each of said Kelly bar sections having a polygonal cross-section with flat faces in said central region, said rotary drive table is positioned at the bottom of said lead column, a roller drive assembly connected to said rotary drive table, said roller drive assembly having a plurality of rollers, each roller mounted to rotate about a horizontal axis parallel to one of said polygonal faces, each roller contacting a flat face of said central region of said Kelly bar, whereby as said rotary drive table rotates around said vertical (A-A) axis, said roller drive assembly rotates said Kelly bar around said vertical (A-A) axis, wherein each Kelly bar section is tapered at its upper and lower ends in a manner whereby the cross-section of said upper and lower ends is reduced toward said upper tip and said lower tip, and wherein when either said upper tip or lower tip of a Kelly bar section is adjacent said roller drive assembly, said rollers do not contact a flat polygonal face or said tapered upper or lower end of said Kelly bar section, whereby said rotary drive assembly is free to rotate relative to said Kelly bar section without causing rotation of said Kelly bar section around said (A-A) axis, whereby misaligned adjacent Kelly bar sections may pass through said roller drive assembly.