US Patent 7353889 Rotary driven pipe-bursting tool

An apparatus for bursting pipe is preferably adapted to receive rotational energy from the inner member of a dual-member drill string. In a preferred embodiment, a plurality of pipe-bursting members, driven by the interconnected inner members, cut or burst a subterranean pipe. In another preferred embodiment, a plurality of screw drives move the pipe-bursting members between an expanded position and a retracted position in response to rotation of the interconnected inner members.