Patent ID: 7617889
Filing Date: 2009-11-17
Classification: E21B

Abstract:
1. A portion of a drill assembly operated by a supply of compressed fluid, comprising: a backhead having a proximal end connectible to the supply, an axial bore and an open distal end having defined therein an integrated cylinder portion, the backhead having passages extending between the axial bore and outer surface of the backhead; a hollow elongate wear sleeve having a proximal end to which the backhead is coupled and into which the distal end of the backhead is received; and a piston housed by the wear sleeve and having a proximal end shaped to fit within the integrated cylinder portion of the backhead, the piston being slidably movable along the wear sleeve and the integrated cylinder portion in response to compressed fluid conveyed through the backhead, wherein an intake flow path for an intake flow of compressed fluid in the drilling tool extends in a distal direction from the axial bore, through the passages in the backhead, through a space between the backhead and the wear sleeve and into an area between the piston and wear sleeve and into contact with the piston, and wherein the intake flow path is free from sharp bends.