Patent ID: 8397839
Filing Date: 2013-03-19
Classification: E21B

Abstract:
1. A down-the-hole drill hammer comprising: a casing; a drill bit proximate to a distal end of the casing; a piston configured within the casing to reciprocally move within the casing along an axial direction, the piston including at least one helical spline on a piston surface; a first sleeve circumscribing the piston, the first sleeve including at least one helical spline mating with the at least one helical spline on the piston surface; a second sleeve circumscribing the piston, the second sleeve having a plurality of splines engaging corresponding splines on the drill bit, the first sleeve and the second sleeve forming a clutch surface; a third sleeve circumscribing the piston, and a wrap spring that operatively engages the clutch surface, wherein the first, second and third sleeves are housed within the casing and have substantially the same outside diameter.