Driver

Abstract

A driver or dogging element adapted to transfer torsion forces between a rotating outer tube ( 10 ) and a drill bit ( 1 ) of a down-the-hole hammer, wherein the dogging element ( 7 ) is made of a softer material than those parts ( 3, 4 ) of the drill bit ( 1 ) that co-act with the dogging element ( 7, 8 ).

1 . A dogging element adapted to transfer torsion forces between a rotating outer tube ( 10 ) and a drill bit ( 1 ) of a down-the-hole hammer, characterised in that the drill bit ( 1 ) comprises a shaft ( 3 ) made of steel and that the dogging element ( 7 ) is made of a softer material than the parts ( 3 ,  4 ) of the drill bit ( 1 ) that co-act with the dogging element ( 7 ,  8 ).  
     
     
         2 . A dogging element according to  claim 1 , characterised in that the dogging element ( 7 ) is provided internally with splines ( 8 ) which are intended for co-action with splines ( 4 ) provided on the shaft ( 3 ) of the drill bit ( 1 ).  
     
     
         3 . A dogging element according to  claim 1 , characterised in that the dogging element ( 7 ) is made of a bronze alloy.  
     
     
         4 . A dogging element according to  claim 3 , characterised in that the dogging element ( 7 ) is made of tin bronze material.  
     
     
         5 . A dogging element according to  claim 3 , characterised in that the dogging element ( 7 ) is made of a chromium bronze material.  
     
     
         6 . A dogging element according to  claim 1 , characterised in that the dogging element ( 7 ) is made of a mterial that has high thermal conductivity.