Patent ID: 7055621

Claim:
An impactor useful in underground pipe replacement, comprising: a head having a rearwardly opening recess and a front end opening that communicates with the recess; an inlet pipe connectable at one of its ends to a source of compressed air, which pipe extends into the recess of the head through the front end opening; a striker mounted for sliding movement along the inlet pipe; a distributing mechanism which receives pressure fluid supplied through the inlet pipe to cause the striker to reciprocate in the rearwardly opening recess of the head to deliver forward impacts against the head; a tubular housing in which the striker and distributing mechanism are mounted; a pulling connection by which the impactor can be pulled while the striker is delivering impacts against the head in the same direction as a pulling force exerted by the drill string; and a valve which regulates supply of pressure fluid to the distributing mechanism, which valve is operable by application and relaxation of pulling force on the pulling connection.