Patent ID: 6273201
Filing Date: 2001-08-14
Classification: E21B

Abstract:
A ground piercing tool, comprising:an elongated tubular tool housing;a striker disposed for reciprocation within an internal chamber of the housing to impart impacts to a front impact surface for driving the tool forwardly through the ground;an air distributing mechanism that reciprocates the striker in response to a supply of compressed fluid;an anvil disposed in a front end opening of the tool housing, which anvil includes a rear, outer frustoconical portion which engages a like-shaped forwardly tapering inner wall of the housing whereby the anvil is held in the housing, the anvil having a lengthwise bore therein, and a rear end of the anvil defining the front impact surface for the striker; anda chisel slidably disposed in the bore of the anvil, which chisel is movable between a rearwardmost position at which a rear end portion of the chisel protrudes from the bore of the anvil to receive an initial impact from the striker, and a forwardmost position at which the striker can impact directly on a rear impact surface of the anvil.