Abstract: The present invention relates to a flapper valve for a percussion drill tool. The valve comprises a first side engageable with a planar surface of an element of the percussion drill tool to alternately close first and second fluid flow paths of the percussion drill tool. The planar surface comprises first and second apertures in fluid communication with the first and second fluid flow paths, respectively. The first side of the flapper valve comprises a first planar portion and a second planar portion and a first curved tip portion intermediate the first and second planar portions. The flapper valve is pivotable about the first curved tip portion between a first position, in which the first planar portion of the flapper valve is in sealing contact with the planar surface to close the first aperture, and a second position, in which the second planar portion of the flapper valve is in sealing contact with the planar surface to close the second aperture.

Abstract: A piston actuated drilling tool includes a housing, a top sub, a piston and a drive sub. The piston has a nose at its forward end that is slidably mounted for reciprocating movement within the housing and which strikes a mandrel located at the forward end of the housing. An integrated retaining and bushing system has a retaining ring arranged for preventing the mandrel from detaching from the rest of the tool. The retaining ring encases a bushing for co-operation with the piston nose to stabilise and guide the piston and provide a timing event for percussion of the tool.

Abstract: A down the hole drilling assembly having an elongate casing, a fluid powered piston, top and bottom working chambers, a plurality of fluid passages and an exhaust system, wherein the sum of the top work area and a top intermediate work area of the piston is equal to the cross-sectional area of the casing bore.

Abstract: A system and method for securely cradling a subsea pipeline is claimed that lands on one side of the pipeline, is embedded into the sea floor, reaches under the pipeline, positions the cradling structure, and then lifts the pipeline. The system typically comprises a gravity driven pile based device, comprising a pile tower, a roller carriage assembly, and a jacking assembly that engages the roller carriage assembly and pile tower rails.

Abstract: An insert bushing arrangement of a breaking hammer, a breaking hammer and a method of supporting a breaking tool of a breaking hammer is provided. The insert bushing arrangement includes a bearing support inside which an insert bushing is mountable. Between the bearing support and the insert bushing is one or more intermediate material layers for preventing jamming of the components.

Abstract: A reversible pipe ramming tool used in horizontal pipe replacement operations. The tool is powered by a pneumatic hose attached to a rear end of the tool. The tool has forward and rearward fluid paths, which can either communicate with one another or stand in isolation. Fluid flow along the forward fluid path, when it is maintained in isolation from the reverse fluid path, causes the tool to move in a forward direction. Fluid flow along the forward fluid path, when it is maintained in communication with the reverse fluid path, causes the tool to move in a rearward direction. The tool is switched between forward and reverse by flowing fluid through a pilot fluid path in fluid communication with a valve. Movement of a shuttle within the valve selectively isolates the forward fluid path from the reverse fluid path.

Abstract: A modular motor is disclosed that includes a piston/harmonic drive assembly that is axially cycled. The piston/harmonic drive assembly is coupled to a ball transfer arrangement that converts the axial motion into rotary motion to rotate a rotor that can be used to rotate a drill bit.

Abstract: An impact generator includes a housing having an uphole end and a downhole end and defining a chamber therein between the uphole and downhole ends. A mandrel is movably arranged at least partially within the chamber between an engaged configuration and a disengaged configuration, and a top sub is coupled to the housing at the uphole end and has an upper core extension arranged at least partially therein. The upper core extension is configured to move between a fixed position, where the mandrel is maintained in the engaged configuration, and an unfixed position, where the mandrel is able to move to the disengaged configuration. An impact tool is coupled to a distal end of the mandrel to deliver an impact force to a downhole obstruction when the mandrel is moved to the disengaged configuration.

Abstract: A hydraulic jar comprising a housing and a mandrel slidably disposed in the housing forming an annular space therebetween. In an embodiment, the hydraulic jar comprises a flow control device fixedly connected to the mandrel and disposed in the annular space to divide the annular space into a first portion and a second portion. The flow control device comprises an annular member slidably positioned about the mandrel, wherein the annular member comprises a face, an inside surface, and an outside surface, wherein the outside surface of the annular member is disposed against an inside surface of the tubular housing, wherein the outer surface of the annular member and the inside surface of the tubular housing allow fluid flow therebetween at a first flow rate, wherein the inside surface of the annular member and the retaining surface of the retaining assembly allow fluid flow therebetween at a second flow rate.

Abstract: A dust shroud assembly for a power tool includes a shroud portion, a barrel, and a helical spring. The barrel includes an upper portion slidably received within a first end portion of the shroud portion. The barrel defines a helical channel. The helical spring is at least partially rotatably engaged with the helical channel and rotationally fixed with respect to the shroud portion. The helical spring is configured to bias the barrel outwardly from the first end portion.

Abstract: A method and means of minimizing the effect of elastic valve recoil in impact applications, such as percussive drilling, where sliding spool valves used inside the percussive device are subject to poor positioning control due to elastic recoil effects experienced when the valve impacts a stroke limiting surface. The improved valve design reduces the reflected velocity of the valve by using either an energy damping material, or a valve assembly with internal damping built-in, to dissipate the compression stress wave produced during impact.

Abstract: A hydraulic head clamp assembly is integral with a drill head mounted on a mobile drill rig. A side-shift carriage is provided for shifting the drill head from side-to-side relative to a centerline of a drill rod string. The clamp assembly includes a rigid jaw mounted on the side of the drill head, and a movable jaw mounted adjacent to said rigid jaw with a space between the jaws for receiving the drill rod string. The movable jaw is connected to a pair of hydraulic cylinder actuators that are actuated via a hydraulic circuit to control the clamp action between the rigid jaw and the movable jaw. The clamp assembly can be used to retract a drill rod string from the ground without limiting access to the inner diameter of the drill rod, and can also be used to advance the drill rod into the ground via a static push.

Abstract: An impulsive unit for a jack hammer or rock drill is adapted to be powered by water, and comprises a piston slidable within a cylinder, and carrying a striker portion thereon. At least a portion of the piston and/or cylinder is coated with ceramic. The ceramic is most suitably an aluminum oxide-titanium dioxide composite, which enables the clearance between the internal diameter of the cylinder and the external diameter of the piston to be reduced to between 8 and 10 micro-meters.

Abstract: A pneumatic device control apparatus and method comprising a ported valve slidably fitted over a feed tube of the pneumatic device, and using a compliant biasing device to constrain motion of the valve to provide asymmetric timing for extended pressurization of a power chamber and reduced pressurization of a return chamber of the pneumatic device. The pneumatic device can be a pneumatic hammer drill.

Abstract: The invention relates to a rotary drive assembly for a drill rod having an outer tube and an inner rod extending at least in sections inside the outer tube, comprising a first gear unit having at least a first drive unit for driving the inner rod in a rotating manner and a second gear unit, which is offset to the said first gear unit in the longitudinal direction of the drill rod and has at least a second drive unit for driving the outer tube in a rotating manner. In accordance with the invention provision is made for the second drive unit to be spaced from the second gear unit and for the second drive unit to be arranged adjacent to the first drive unit on the first gear unit.

Abstract: A suction device (11) for a hammer drill (6) has a first end (12) with a securing device (14) for securing the suction device (11) to the hammer drill (6) and a second end (13) opposite first end (12) and which has a contact area (15) with which the suction device (11) contacts a constructional component, the suction device (11) further having a receiving space (20) which at least partially encloses a working tool (7) of the pick power tool (6), and being provided with a connection device (18) for a vacuum source. A retaining element (21) having a through-opening (22) for the working tool (7) and a plurality of suction openings (23) is provided in an area (19) of the second end (13).

Abstract: The invention discloses a fluid-driven impactor, a power transmission mechanism for the impactor and the use of the impactor. In the prior art, the working life of the impactor is short, since a rubber primary seal and an upper fluid-diverging lid for the fluid-driven impactor are both liable to erosion and the efficiency in transmitting power is low due to the complexity of the power transmission mechanism. In order to increase the drilling speed and/or extend the life of the impactor, the side cavity passage is formed in such a way that the inner wall of the outer pipe is isolated from the side cavity passage in a watertight manner without the use of the rubber primary seal. The loss in transmitting power is minimized by integrating the anvil of the power transmission mechanism and the lower joint.

Abstract: A sleeve carried by and preferably slidable relative to the piston, for controlling air passages associated with a central air feed tube, whereby retraction pressure is applied to the piston substantially at impact. It is the impact itself of the piston against the bit, which enhances sliding of the sleeve relative to the piston, over the feed tube, and thereby switches the airflow at the moment of impact.

Abstract: A hydraulic rock drill comprises a housing having a piston and valve bore formed therein, a rotation motor, and a fluid connection and fluid reservoir interposed between the housing and the rotation motor. Fluid connections to the hydraulic rock drill comprise a single inlet fluid connection to the housing and a single exhaust fluid connection from the rotation motor. The working shoulder areas of the piston are proportioned so that the exhaust stroke of the piston will pressurize the fluid in the reservoir, providing a fluid inlet source for the rotation motor. When the rotation torque demand increases, pressure in the fluid reservoir and pressure in the fluid inlet connection will rise accordingly, thus providing higher rotation torque while maintaining impact power. When fluid inlet pressure reaches a predetermined limit, rotation and impact will lessen or cease altogether.

Abstract: A power swivel provides the rotational force to drill consolidated subsurface strata while an unrestricted airflow through the swivel and down a drill string remove cuttings from the borehole. The power swivel is configured to mount on direct push equipment, such as a cone penetrometer, to eliminate the need for a conventional drilling rig when a consolidated layer is encountered during direct push operations. A drilling nipple and pack-off are provided near the surface to maintain the air flow during drilling and to direct the cuttings to a desired location. Also, a dual-valved air delivery system provides safe, remote-controlled air flow to the swivel.

Abstract: Provided is a downhole percussion drill, which is installed at an end portion of a drillstring and performs drilling by giving impact blows to a drill bit at the bottomhole, which includes a hydraulic hammering mechanism 7 which uses oil having high lubricating ability as a driving medium, a hydraulic pump 8 which pressurizes the oil, and a downhole motor 9 which drives the hydraulic pump 8.

Abstract: An improved bidirectional hydraulic jar. The jar comprises a two-ring valve assembly supported preferably on the inner mandrel for reciprocal movement inside a fluid chamber. The chamber comprises two larger portions joined by a narrowed restrictor portion. The valve obstructs passage of fluid through the restrictor portion except for a bleed passage, which comprises an adjustable metering space between the two valve rings. The jarring force can be adjusted by varying the size of the metering space, which is done simply by axially repositioning one of the valve rings. All impact surfaces are enclosed in the housing to prevent downhole debris from dampening the blows. The shoulder on the exposed end of the mandrel is champfered to prevent build-up of debris and to facilitate removal of the tool from the well. This jar can be re-cocked easily, without firing in the reverse direction, for unidirectional jarring operations.

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: A hydraulic percussion drill includes a piston hammer disposed in a cylinder for reciprocating movement in response to pressure fluid acting continuously on one transverse face of the piston hammer and in response to valving of pressure fluid alternately to an opposed piston face of the piston hammer by a tubular sleeve valve disposed around the piston hammer. The drill includes a percussion bit configured to have a face portion disposed at an acute angle with respect to a plane normal to the bit and the drill central axis. Cooperating spiral splines on the bit and a bit chuck provide for directional drilling using a method which includes causing the bit to receive impact blows without rotating the cylinder housing to initiate a deviated drillhole.

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 hydraulic breaker for absorbing and reducing vibration and noise generated from the breaker and for reducing debris and dust scattered from the impact tool during using the breaker is provided. Space between main body of the breaker and outer housing is filled with fluid supplied from outside of the outer housing. Fluid hose is connected to a fluid hole formed on the outer housing to supply fluid into the space. Upper absorber is disposed between a bracket and upper portion of the main body, lower absorber is disposed between front cover of the outer housing and front head portion of the main body. Side absorbers are disposed between sidewall of the outer housing and outer cylindrical sidewall of the main body to keep a distance between outer housing and main body and to provide the space filled with fluid. Fluid, such as water, filled in the space is ejected through holes formed on the front cover of the outer housing.

Abstract: A down-the-hole percussive drill comprises a casing, a drill bit mounted at a lower end of the casing, a hollow feed tube fixed within the casing and extending along a center axis thereof, and a piston mounted for axial reciprocation within the casing for transmitting impacts to the drill bit. The upper portion forms a downwardly facing surface at the junction between the upper and lower portions. Passages for conducting lubricant-containing pressurized air are formed in the piston. At least one of those passages constitutes a vertical recess formed in the outer periphery of the piston. The piston includes a radially outwardly projecting rib disposed between upper and lower ends of the recess. Air is blocked from traveling past the rib until the rib becomes located opposite an annular groove formed in an inner surface of the casing.

Abstract: In an air actuated down-the-hole hammer for rock drilling, a piston reciprocates within a casing to impact against a rear anvil surface of a drill bit. A foot valve extends axially between the piston and the drill bit. The anvil surface is inclined downwardly in a radially outward direction to cause liquid on the anvil surface to be discharged in a direction away from the foot valve, to prevent damage to the foot valve which could occur if piston impacts were able to create high-speed liquid streams contacting the foot valve.

Abstract: A down-the-hole percussive drill comprises a casing, a drill bit mounted at a lower end of the casing, a hollow feed tube fixed within the casing and extending along a center axis thereof, and a piston mounted for axial reciprocation within the casing for transmitting impacts to the drill bit. The piston has a stepped configuration in that a lower portion thereof is of smaller outer diameter than an upper portion thereof. The upper portion forms a downwardly facing surface at the junction between the upper and lower portions. Air-conducting passages are formed in the upper portion of the piston and are supplied with pressurized air from the hollow feed tube. One of those passages intersects the downwardly facing surface of the upper portion of the piston. The hollow feed tube is mounted to a top sub of the drill by pins which are mounted in the top sub and extend radially into a sidewall of the feed tube, the pins being situated outside of the central passage.

Abstract: An in-hole hammer for boring in ground has an elongated hollow housing carrying an internal striking piston in a piston chamber. An exchangeable boring head is threadably connected to the forward end of the housing and the striking piston impacts against the forward wall of the housing defining the piston chamber to transmit forward driving impact energy to the boring head. A boring rod which urges the hammer forwardly and rotates it about the longitudinal axis is connected to the rear end of the housing through a connecting piece non-rotatably fixed, but slidable relative, to the housing so that the axially directed impact energy produced by the striking piston is not transmitted to the boring rod.

Abstract: A improved "mud motor" for use in oil and gas well drilling includes a reciprocating valve and piston arrangement that generates power using drilling fluid media (e.g., drilling mud) pumped through an inlet port to form a differential across a piston seat. The differential pressure causes the valve and piston assembly to move down in an elongated body. Rollers then force telescoping, reciprocating fingers to rotate while absorbing the reciprocating up and down action of the valve and piston assembly. This clockwise rotation causes a transmission that includes a clutch shaft and sprags to engage a clutch housing causing the drill bit to turn. Thrust bearings allow weight to be applied to the tool to optimize drilling action. The apparatus can be used in well drilling or in the removal of obstructions such as bridge plugs, metal and rubber from the well bore.

Abstract: A pneumatic downhole impact drill has a porting system for automatically supplying pneumatic pressure fluid from a fluid delivery tube received within an axial bore in the impact piston to the opposite ends of the piston operating cylinder as the piston reciprocates. A flange on the delivery tube is slidably mounted in a cavity in a mounting hub assembly. Passageways provide fluid communication between the pressure fluid inlet plenum and the operating chamber side of the cavity and between the back chamber and the inlet plenum side of the cavity. Fluid pressure forces acting on the opposite faces of the flange and on the top end surface of the delivery tube reciprocate the delivery tube between upstroke and downstroke positions. Positioning the delivery tube in the upstroke position increases the axial distance that the piston must travel before the pressure fluid supply is connected to the back end of the operating chamber on the piston upstroke.

Abstract: The invention provides an In-The-Hole hydraulic drive unit for rotating a rock drill. A hydraulic motor having a fixed rear trailing end and a rotating front drilling end converts hydraulic power into a rotational drive force. The hydraulic motor receives high pressure hydraulic fluid through a receiving inlet and discharges lower pressure hydraulic fluid through a hydraulic outlet. A drive shaft connected to the rotating front drilling end is disposed within the hydraulic motor. A fluid transfer conduit within the drive shaft transfers hydraulic or pneumatic drill fluid to power the rock drill. The fluid transfer conduit bypasses the hydraulic motor for independent supply and operation of the rock drill. The fluid transfer conduit receives the drill fluid from the surface and transfers the drill fluid toward the rock drill. The drive shaft contains a drill rotator attached to the front drilling end adapted to receive and rotate the rock drill.

Abstract: A hydraulic reciprocating percussion tool, particularly adapted for drilling applications, comprises an elongated cylinder, opposed fronthead and backhead members and a central bore in the cylinder for supporting a reciprocating piston hammer. The piston hammer has reduced diameter end portions which have respective tubular sleeve valves disposed in sleeved relationship thereon and engageable with valve retainer members on the reduced diameter portions for effecting movement of the valves with the piston hammer. The head members include tubular sleevelike stem portions which cooperate with the respective valves to valve pressure fluid to and from opposed chambers in the cylinder to effect repeated impact blow delivering strokes to a shank member disposed in a chuck connected to the fronthead.

Abstract: A pneumatic hammer is provided which includes a working piston (16) movable in a working cylinder (22) and defining therewith front and rear cylinder working chambers (23, 24, respectively). The working piston (16) impacts upon an anvil (15) to drive a drill bit (12) through utilizing a source of compressed air. An adjusting mechanism (37) adjusts the length of the return stroke of the working piston (16) in dependence upon the supply pressure of the compressed air.

Abstract: A fluid distributor for a debris flushing system in a fluid-activated jackhammer includes a bore through a reciprocal piston, for fluid flow into an exhaust chamber, a fluid distributor removably mounted in the piston bore, the fluid distributor operating by forming passageways through the bore and blocking flow in other portions of the bore. The distributor can have a tapered body that can be severed along its length by the operator to provide a plurality of preselected, fixed flow rates.

Abstract: Improvements in down-hole mud actuated hammers are disclosed. According to its broadest aspect the invention is a down-hole mud actuated hammer for use in a drill string, which includes a housing with an upper end having means for connecting to the drill string. A throat is located within the housing which throat includes a main flow passage to allow high pressure drilling mud to pass therethrough. A piston is provided which is adapted to move axially within the housing means to thereby reciprocate between an up position and a down position. The piston is moved between the up and down position by a minor portion of the high pressure mud which portion passes from the main flow passage into at least one piston actuating chamber. This minor portion of mud is exhausted from the piston actuating chamber to a low pressure region out of the housing without being returned to the main flow passage.

Abstract: A throttle lever system for operating a flushing system on a percussive, fluid-activated apparatus includes a fluid inlet port, passageways in the apparatus for exhaust fluid, a seal device for opening and closing the passageways, and a throttle lever system for operating the seal device, the throttle lever system including a one-piece throttle lever elastically and pivotally mounted on a pivot pin on the device to cantilever out over the seal device, whereby the lever elastically moves up and down into and out of contact with the seal device, in response to operator hand pressure.

Abstract: Hammer device comprising a machine housing (1) with a hammer piston (2) movable to-and-fro. The movement to-and-fro of the hammer piston is controlled by a valve body (6) movable to-and-fro in the machine housing. In order to speed up the turning of the hammer piston at its rear end position the machine housing is provided with a room (10) which by the hammer piston is separated from connection with the valve body (6) at the same time as the rear end surface (5) is supplied with pressure fluid via a connection (11) opened by the hammer piston to the pressure source (8) when the hammer piston approaches its rear end position.

Abstract: A pneumatic hammer is provided with an adjusting piston (37) dependent on the supply pressure, which adjusts the stroke length of the working piston (16). Thereby, the same pneumatic hammer may be operated both at low and high supply pressures. With high supply pressures, either the early ending of the acceleration phase or the early start of the compression phase or the shortening of the working cylinder shortens the stroke length. Thereby, the pneumatic hammer performs impacts with a substantially constant single-impact energy, regardless of the supply pressure. High supply pressures increase the impact frequency. This results in a considerably improved efficiency at a high drill capacity, a reduced wear and a reduced risk of ruptures of the components of the hammer.

Abstract: Down-the-hole drill comprising a housing (1), a hammer piston (6) movable to-and-fro in the housing and intended for impacting a drill bit (5). A back piece (3) provided with an extension (12) with a valve part (17) cooperates with a part (8) of a central channel in the hammer piston. This part of the central channel comprises a zone (16) with larger diameter than adjacent parts at an intermediate part of this part. This results in that pressure medium can pass the valve part when it is situated at the zone and that the valve part and the hammer piston sealingly cooperate when the valve part is on either side of the zone.

Abstract: A debris flushing system for a percussive, fluid-activated apparatus includes a first and second separate and independent flushing system in the apparatus, each flushing system having a separate combination of passageways in the apparatus for fluid communication between an inlet port and a front piston exhaust chamber. Each flushing system has a separate seal and throttle combination for opening and closing its own passageways. A third, independent flushing system for flushing water can be added to the apparatus.

Abstract: A percussive, fluid-activated jackhammer includes a low pressure lubrication system having a liquid lubrication reservoir chamber formed in a bore of the jackhammer, the lubrication chamber being subject to low percussive fluid pressure in a front piston chamber but not to high percussive fluid pressure in a drive or return chamber of the device. An inlet passageway is provided for adding lubricant to the lubricant chamber. An outlet passageway is provided, with a metering device therein, for flow of lubricant into the bore of the device during reciprocation of a piston in the bore.

Abstract: A downhole oil well tool uses impact, reciprocal drilling and an improved rotating bit or like working member, receiving both fluid pressure and weight from an elongated pipe string with a flow bore in order to drive the tool. A valve within tool housing controls fluid pressure to the working end so that the tool pressures up, then releases pressure through the working member allowing the pipe string to load the bit, creating impact. A clutch rotates the working member during drilling to prevent imprint upon the formation. A bias spring is provided to control and adjust the amount of weight on the bit independent of pipe weight.

Abstract: A pneumatic percussion hammer for attachment to a drill tube is coaxially constructed about an outflow tube which is mounted therein for axial removal and replacement when worn. A cylindrical piston moves axially between a top sub wherein a drill stem is screwed, and an anvil of a bit at the bottom. A casing and the piston are configured to valve the flow of pressurized air therethrough for reciprocating motion of the piston and an outflow that carries debris through the outflow tube and drill stem.

Abstract: A downhole percussion drill or hammer (100) is disclosed having an outer casing (2) in which a reciprocating piston (26) which periodically impacts a drilling bit (16) disposed at a bottom end of the casing. A top chuck (1), attached to the top end of the casing, conducts pressurized air to the interior of the casing. A flow tube (5) includes a supply passage (27) and an exhaust passage (10). No cylinder sleeve exists between the inner diameter of the casing (2) and the outer diameter of the piston (26). Rather, the flow tube (5), piston (26) and interior structure of the casing cooperate to direct pressurized air alternately to the top and bottom ends of the piston while alternately opening and closing the exhaust passage. Accordingly, for a predetermined outer casing diameter, a relatively thicker casing wall and relatively larger top piston surface results in higher relative performance than prior hammers having a cylinder sleeve.

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: In a water driven down-the-hole rock drill, the rearward end of an associated hammer is provided with a drive piston reciprocable in a cylinder located adjacent the rear of the drill. The front end of the hammer is guided for reciprocation in a bearing located adjacent an anvil of a drill bit. Between the cylinder and the bearing the hammer is elongated and enlarged diametrically relative to the piston. The enlarged hammer portion reciprocates freely in a chamber formed by an outer casing of the drill. Drive water is expelled from the cylinder and flushes the hole drilled by the bit. An open ended tubular valve reciprocates to control a duct connecting the interior of the valve to coaxial through-flushing channels in the hammer and the drill bit.

Abstract: A fluid actuated percussion rock drill comprising a hollow wear sleeve and a piston slidingly disposed within the wear sleeve. Drive and return pressure surfaces bias the piston between drive and return positions, respectively. A high pressure port is included. A return chamber is exposed to the return pressure surface. A drive chamber is exposed to the drive pressure surface. A pressure sensitive valve is movable between an open and a closed position. When the valve is in the open position, the high pressure port is connected to the drive chamber. The valve includes a first valve pressure surface for exposure to the drive chamber and a second pressure surface for exposure to the high pressure port. A third valve pressure surface is exposed to an outlet pressure port. The volume of fluid travels between the high pressure port and the drive chamber when the valve is in an open position can be limited as desired for different drill applications.

Abstract: The invention is concerned with pneumatic percussion drilling equipment with advantageous manufacturing simplicity and effective piston area to casing size consisting essentially of an elongate hollow casing housing a piston assembly and having a backhead at one end with a compressed fluid inlet, a bit assembly with a compressed fluid exhaust at the other end, and the backhead including a seal for a backhead end of the piston reciprocatable within the casing, the piston having axial bores extending inwardly from each end, inclined passages extending away from the inner ends of the axial bores to open through the wall of the piston at positions axially displaced from each other and towards opposite ends of the piston from their respective axial bores, and the casing walls having axially spaced apart recesses, the backhead seal, casing recesses and opening through the wall of the piston being such as to allow fluid under pressure introduced axially into the casing through the backhead, to reciprocate and to mai