A DRIVE SUB FOR RECEIPT OF BIT SEGMENTS

摘要

A DRIVE SUB FOR RECEIPT OF BIT SEGMENTS A drive sub adapted for connection to a lower end of a ground drill, said drive sub comprising a tubular member provided with seating means formed circumferentially about an inner wall of said tubular member for seating cutting means of said ground drill in a cutting position, said seating means comprising a series of surfaces configured and juxtaposed so that cutting means can slide relative to said member when in said cutting position in response to said ground drill being lifted from and lowered onto the bottom of a hole being drilled by said ground drill.