This invention relates to an air operated impact hammer adopted to drill bore holes through solid rock. The hammer itself is adapted to be attached to a drill string which conveys air under pressure to the hammer, the air pressure normally coming from air compressors at the surface. The air-conveying drill string may rotate as the hammer positioned at its lower end does its job of cutting away through rock. The air inside the hammer ultimately exhausts through the bottom of the hammer where the drilling bit is positioned. The rising stream of air thus carrying to the surface dust, sands and rock fragments cut by the hammer as it drills through the rock.
The particular efficacy of this air hammer is its simplicity. Other than the hammer piston inside the outer casing of the hammer, there are no moving parts to channel the air appropriately both to lift and to drive down the hammer piston. Thus the reciprocating hammer piston, in addition to striking the bit with sufficient force to chip away rock, also serves to direct air through the appropriate ports inside the hammer as the hammer piston reciprocates. Accordingly, it is the primary object of the present invention to supply a simplified and efficient air supply to its hammer which makes it capable of use for extended periods of time without shutdowns caused by wear of internal parts, plugging of moving parts, or other operational hazards.