Abstract: The invention provides a drill bit for a down-the-hole drill hammer. The bit has a head at its forward end with a shank extending from the head. The shank is screw threaded along its length. A reciprocating chuck is provided as a sleeve with internal screw threads corresponding to those of the shank. The shank is releasably secured in the chuck with the rear end of the shank providing a striking face. An arrangement of external splines on the chuck, and a retaining shoulder at its rear end, provide for the required guided movement of the chuck within a drill hammer wear sleeve. The bit is simple to machine with screw threads replacing the usual splines and other structural features ordinarily required on this component. These features are instead provided on the chuck and in the wear sleeve.

Abstract: The invention provides for a down-the-hole drill bit assembly comprising a drill bit having a screw-thread at its anvil end, external splines on the drill shank and co-operating splines within a drill casing as well as a co-operating screw thread carried by a component within the casing. The assembly is arranged to have engagement of the splines with the screw threads disengaged for driving the drill and to have the screw threads engaged and splines disengaged to permit removal of the bit from the assembly.

Abstract: A percussive drill bit provided with an improved chuck assembly for a down-the-hole drill hammer. The bit has a head at its forward end with a shank extending from the head. The shank is screw threaded along its length. A reciprocating chuck is provided as a sleeve with internal screw thread as corresponding to those of the shank. The shank is releasably secured in the chuck with the read end of the shank providing a striking face. An arrangement of external splines on the chuck, and a retaining shoulder at its rear end, provide for the required guided movement of the chuck within a drill hammer wear sleeve.

Abstract: A percussive drill bit provided with an improved chuck assembly for a down-the-hole drill hammer. The bit has a head at its forward end with a shank extending from the head. The shank is screw threaded along its length. A reciprocating chuck is provided as a sleeve with internal screw thread as corresponding to those of the shank. The shank is releasably secured in the chuck with the read end of the shank providing a striking face. An arrangement of external splines on the chuck, and a retaining shoulder at its rear end, provide for the required guided movement of the chuck within a drill hammer wear sleeve.

Abstract: A pneumatic hammer comprises an elongate hollow casing with operatively upper and lower ends and has a piston slidingly received within the casing and operable to reciprocate within the casing between upper and lower pressure chambers defined within the casing. The hammer further has an axially displaceable bit assembly at the lower end of the casing and a backend assembly at the upper end of the casing. The piston has a striking face at an end thereof proximate the bit assembly, and the piston is operable to impact on a contact surface of the bit assembly in an impact region of the casing. The hammer is characterized in that the piston is shaped and dimensioned at its proximal end to have a snug sliding fit with an interior of the casing in the impact region of the casing.

Abstract: The invention provides a down-the-hole drill assembly having exhaust passages from upper and lower chambers past the inner end of a bit and through the body of the bit to exit through the bit face. The construction of the assembly and bit obviates a foot valve tube from the head of the bit and the disadvantages associated with this component.

Abstract: The invention provides a down-the-hole drill assembly having exhaust passages from upper and lower chambers past the inner end of a bit and through the body of the bit to exit through the bit face. The construction of the assembly and bit obviates a foot valve tube from the head of the bit and the disadvantages associated with this component.

Abstract: The invention concerns a reverse circulation rock drill having a backhead attached to a piston and cylinder assembly between the backhead and a drill bit assembly and around a sample tube with the outer walls of the sample tube and piston profiled to provide air paths for power and exhaust strokes of the piston, a O-ring seal being provided in the backhead as a check valve.

Abstract: The invention concerns a down the hole drill hammer assembly providing a full piston area exposure to driving fluid pressure by the omission of the usual finger valve from the upper piston area and providing the piston with blind bores at each end and passages through the piston wall enabling predetermined communication between the blind bores for exhausting pressure fluid through the drill bit assembly. Fluid transfer passages are also provided in the inner wall of an outer wear sleeve of the drill hammer assembly.

Abstract: The invention concerns a reverse circulation rock drill having a backhead attached to a piston and cylinder assembly between the backhead and a drill bit assembly and around a sample tube with the outer walls of the sample tube and piston profiled to provide air paths for power and exhaust strokes of the piston, a O-ring seal being provided in the backhead as a check valve.

Abstract: The invention concerns a down the hole drill hammer assembly providing a full piston area exposure to driving fluid pressure by the omission of the usual finger valve from the upper piston area and providing the piston with blind bores at each end and passages through the piston wall enabling predetermined communication between the blind bores for exhausting pressure fluid through the drill bit assembly. Fluid transfer passages are also provided in the inner wall of an outer wear sleeve of the drill hammer assembly.

Abstract: A down the hole drill in which a larger surface area is provided to which a greater quantity of pressure can be applied. The drill includes a piston and cylinder assembly in which the cylinder is divided in to a plurality of longitudinally extending contiguous sections, and the piston is shaped to provide together with the cylinder a drive and lifting chamber in each sections, and the air supply and exhaust provided in separate passages in a control rod which extends along a bore in the pistons, and a piston head is provided in each section.

Abstract: A pneumatic percussion machine such as a drill having a piston reciprocating in a casing, chambers formed in the casing at or towards the ends of the piston, the arrangement permitting compressed air to be supplied alternatively to the chambers, the compressed air to the one chamber being supplied through a projecting member located co-axially in the casing, and over which the piston reciprocates, and the piston and compressed air from the other chamber being exhausted from such chamber between the wall of the casing and a stepped portion of the piston and then through the piston to atmosphere. Provision is made for the piston to move to a position, in an inoperative condition of the machine, in which both chambers are open to the atmosphere.

Abstract: A pneumatic percussion machine such as a drill, having a piston reciprocating in a casing, chambers formed in casing at or towards the ends of the piston, the arrangement permitting compressed air to be supplied alternatively to the chambers, the compressed air to the one chamber being supplied through a projecting member located co-axially in the casing and over which the piston reciprocates and compressed air from the other chamber being exhausted through the projecting member to the other chamber.