Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
B25D9/00—Portable percussive tools with fluid-pressure drive, i.e. driven directly by fluids, e.g. having several percussive tool bits operated simultaneously
B25D9/14—Control devices for the reciprocating piston
B25D9/16—Valve arrangements therefor
B25D9/24—Valve arrangements therefor involving a rocking-plate type valve
E—FIXED CONSTRUCTIONS
E21—EARTH OR ROCK DRILLING; MINING
E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
E21B1/00—Percussion drilling
E21B1/12—Percussion drilling with a reciprocating impulse member
E21B1/24—Percussion drilling with a reciprocating impulse member the impulse member being a piston driven directly by fluid pressure
E21B1/30—Percussion drilling with a reciprocating impulse member the impulse member being a piston driven directly by fluid pressure by air, steam or gas pressure