Inventor
JOHNS ROGER P
US3 patents
Patents
3 patentsUS5305837AApr 26, 1994
Air percussion drilling assembly for directional drilling applications
SMITH INTERNATIONAL94 citations94
USRE36166EMar 30, 1999
Air percussion drilling assembly for directional drilling applications
SMITH INTERNATIONAL25 citations90
US5394952AMar 7, 1995
Core cutting rock bit
SMITH INTERNATIONAL49 citations86