Patent ID: 6293357
Filing Date: 2001-09-25
Classification: E21B

Abstract:
A pressure fluid operated reciprocating piston hammer percussion tool comprising:an elongated cylinder including a central bore;a reciprocating piston hammer disposed in said bore for reciprocation under the urging of pressure fluid supplied to first and second chambers formed in said cylinder between said piston hammer and said cylinder, respectively;an impact blow receiving member supported on said tool and operable to receive repeated impact blows from said piston hammer;a generally tubular sleeve valve disposed in said cylinder between said piston hammer and said impact blow receiving member and operable to be reciprocated in said cylinder by pressure fluid forces acting thereon to effect valving pressure fluid to and venting pressure fluid from one of said first and second chambers to effect reciprocation of said piston hammer to deliver repeated impact blows to said impact blow receiving member;said valve including opposed pressure faces formed thereon and responsive to exposure to pressure fluid to effect reciprocation of said valve in response to movement of said piston hammer; anda third chamber formed in said cylinder and passage means in said cylinder operable to be in fluid flow communication with passage means formed in said piston hammer in a predetermined position of said piston hammer in said cylinder for venting pressure fluid from said third chamber and said cylinder to change pressure fluid forces acting on one of said pressure faces of said valve to effect movement thereof.