Abstract: A valveless-type down-the-hole hammer drill which has an inner tube extending from the upper end of the hammer body into a central opening in a cutter bit reciprocably mounted in a chuck on the opposite end of the hammer body. High pressure fluid is supplied to the interior of the inner tube and a piston surrounding the inner tube has internal surfaces controlling connection of a port to chambers above and below the piston. The external surface of the piston controls connection of these chambers to an exhaust port. A valve sleeve on the chuck coacts with the piston in this respect.

Abstract: A valveless-type down-the-hole hammer drill which has an inner tube extending from the upper end of the hammer body into a central opening in a cutter bit reciprocably mounted in a chuck on the opposite end of the hammer body. High pressure fluid is supplied to the interior of the inner tube and a piston surrounding the inner tube has internal surfaces controlling connection of a port to chambers above and below the piston. The external surface of the piston controls connection of these chambers to an exhaust port. A valve sleeve on the chuck coacts with the piston in this respect.

Abstract: A borehole drill construction comprising a cylindrical casing, a chuck mounted on one end of the casing by means of a screw-thread and a cutter head carried by the chuck. The chuck has at least one axially projecting dog thereon which is received in a corresponding recess in the cutter head to provide a means to transmit torque from the casing to the cutter head via the chuck. The cutter head is retained on the bit by at least one plug projecting into a slot in the cutter head, which is permitted limited axial movement thereby.

Abstract: Apparatus for drilling a bore hole comprising a hammer and a dual walled drill tube. The hammer comprises a reciprocable piston, fluid flow control device for directing fluid under pressure to the hammer to reciprocally drive the piston, and cutting device coupled to the hammer which rotate upon reciprocation of the hammer to cut the bore hole. Rachets are coupled to the cutting device to permit rotation of the cutting means in one direction only and to prevent rotation in an opposite direction. A portion of the fluid under pressure is diverted to entrain and direct particulate material to the surface of the bore hole.