Drill head for directional boring
Drill string jarring and bumping tool with piston disconnect
Drilling device with hydraulic percussion generator for earth dr
Drilling method and measurement-while-drilling apparatus and...
Earth drilling lubricated hydraulic shock absorber and method
Electro-mechanical drilling jar
Enclosed jar tool
Exhaust valve and bit assembly for down-hole percussive drills
Fishing jar for accommodation of excess tensile load
Fluid distributor device for down-hole-drills
Fluid dump mechanism
Fluid operated drill apparatus
Fluid operated vibratory jar with rotating bit
Fluid operated vibratory jar with rotating bit
Fluid operated vibratory oil well drilling tool
Fluid operated vibratory oil well drilling tool with anti-chatte
Fluid Powered drilling jar
Fluid powered rotary percussion drill with formation disintegrat
Fluid retarded accelerating jar with negative and positive press
Hammer device