Patent ID: 8511403

Claim:
A steerable ground piercing tool, the tool comprising: an elongated outer housing having a lengthwise extending bore; and an inner assembly at least in part disposed within the outer housing, the inner assembly comprising; a rotatable chisel having a longitudinally extending shaft at least in part disposed within the housing bore, the chisel having a first end defining an asymmetric tip and a second end defining a first impact surface for receiving a reciprocating action impact to drive the tool through the ground; and a conversion mechanism to selectively convert upon activation thereof at least a first portion of the reciprocating action imparted to the first impact surface into combined reciprocation and rotation of the tool, wherein upon activation of the conversion mechanism and conversion of the reciprocating action imparted to the first impact surface into combined reciprocation and rotation of the tool, the tool pierces the ground in a straight path and wherein in the absence of activation of the conversion mechanism, upon the imparting of impacts to the first impact surface, the tool pierces the ground without rotation and in a curvilinear path.