Patent ID: 8651202

Claim:
A percussion drilling assembly for boring into the earth comprising: a top sub; a casing coupled to the top sub; and a feed tube assembly disposed within the top sub and the casing, the feed tube assembly comprising: a non-rigid coupling having a throughbore; and a tubular body disposed therein; wherein the tubular body is translatable in the radial direction and is pivotable relative to a longitudinal centerline extending through the non-rigid coupling; and wherein the non-rigid coupling interconnects the tubular body and the top sub and further comprises a retention member configured to limit translation of the non-rigid coupling in the axial direction, the retention member being a pin comprising: an elongate body having two ends; a generally cylindrical surface extending between the two ends, wherein the pin is rotatable over the cylindrical surface; and a flat surface extending lengthwise between the two ends, wherein the flat surface is adjacent a lower spacer of the non-rigid coupling.