Patent ID: 7950475

Claim:
A percussion drilling assembly for boring into the earth comprising: a top sub; a casing coupled to the top sub; 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; a first, a second and a third spacer; a first flexible gasket, wherein the first and the second spacer are disposed adjacent opposite sides of a flanged portion of the tubular body, and wherein the first flexible gasket is disposed between the first spacer and the third spacer; a fourth spacer; a second flexible gasket is disposed between the second spacer and the fourth spacer; and a retention member configured to engage corresponding mating holes of the top sub and limit translation of the coupling in the axial direction; wherein the retention member comprises a pin extending through the fourth spacer in a direction substantially normal to a longitudinal centerline extending through the non-rigid coupling.