Abstract: The present invention relates to systems and methods for controlling downhole motors and drilling systems incorporating such systems and methods. One aspect of the invention provides a downhole drilling system including: a downhole motor, a transmission coupled to the downhole motor, and a drill bit coupled to the transmission. Another aspect of the invention provides a method of drilling a borehole in a subsurface formation including the steps of: providing a drill string including a downhole motor, a transmission coupled to the downhole motor, and a drill bit coupled to the transmission; and rotating the drill string while flowing a fluid through the drill string to the downhole motor, thereby powering the downhole motor, thereby rotating the transmission and the drill bit.

Abstract: A drilling tool (10) includes a pilot bit (14) and a plurality of mills (16) encircling the pilot bit. The pilot bit and the plurality of mills are each driven by a separate, hydraulically powered turbine or positive displacement motor. (20) The drilling tool does not include a transmission for transmitting power from the turbine or motor to any of the plurality of mills or the pilot bit.

Abstract: A down hole motor assembly with a locking mechanism, and methods for operating said down hole motor assembly. The down hole motor has a housing operatively connectable at an upper end to a drill string. A shaft is disposed within the housing and operatively connected to a motor portion of the down hole motor. A locking mechanism is configured to selectively transmit torque from the housing to the shaft when engaged.

Abstract: A device for boring a well. The device is attached to a motor that has a power shaft for imparting rotational movement. The device comprises a driver operatively connected to the power shaft, with the driver containing a tubular body, a first bit having a first end connected to the driver so that rotational movement of the driver is imparted to the first bit, and a sleeve disposed about the power shaft, and wherein the sleeve has a radial shoulder. The device further comprises a housing disposed about the driver and a second bit attached to the housing. A plurality of nozzles is operatively placed within the driver, and the nozzles deliver fluid flow to the second bit. The device may further include a planetary gear anchored to the radial shoulder, and wherein the planetary gear is adapted for imparting rotation from the driver to the housing in a counter radial direction.

Abstract: A device for boring a well. The device is attached to a motor that has a power shaft for imparting rotational movement. The device includes a driver operatively connected to the power shaft, with the driver containing a cylindrical body, a first bit having a first end connected to the driver so that rotational movement of the driver is imparted to the first bit, and a sleeve disposed about the power shaft. The device further includes a housing disposed about the driver, and a second bit attached to the housing. Through engagement of cogs and pinions, rotation of the first bit in a first direction using the driver causes counter rotation of the second bit in an opposite direction, significantly reducing or eliminating reactive torque produced during drilling.

Abstract: A universal joint assembly includes an assembly housing, an assembly cap coupled to the assembly housing, a rotatable mandrel, a plurality of substantially spherical drive balls, and a floating washer. The assembly housing has a plurality of pockets formed in an interior surface of the assembly housing. The rotatable mandrel is fitted within a cavity defined by the assembly housing and the assembly cap and has a plurality of pockets configured to partially receive the drive balls. The substantially spherical drive balls are rotatable within the cavity about a central axis of the mandrel. A substantially circular groove formed in the cavity is defined by a proximal end of the assembly cap and an interior wall and a shoulder of the assembly housing. The floating washer is disposed within the substantially circular groove and configured to radially displace within the groove.

Abstract: A downhole tool string component, having a first rotor secured within a bore of the component and connected to a gear assembly, the gear assembly being connected to a second rotor. The gear assembly has a gear ratio adapted to rotate the second rotor faster than the first rotor. The second rotor is in magnetic communication with a stator which has an electrically conductive coil, the electrically conductive coil being in communication with a load.

Abstract: A down-the-hole vibratory unit for a drilling system includes a casing comprising a fluid inlet, and a plurality of eccentrically weighted rotor assemblies positioned at least partially within the casing and in fluid communication with the inlet, the eccentrically weighted rotor assemblies that are unbalanced relative to a central axis and are configured to rotate in response to a fluid flow directed thereto to apply centrifugal forces to the casing.

Abstract: A wellbore motor includes a source of rotational motive power disposed in a wellbore, a magnetic gear member operatively coupled at an input thereof to the source; and a magnetic gear member output coupled rotationally to a rotary wellbore tool.

Abstract: In one aspect of the present invention a downhole tool string has a rotor secured within a bore and connected to a jack element that is substantially coaxial with the rotor. A portion of the jack element extends out of an opening formed in a working face of a drill bit located at the bottom of the drill string. The jack element is adapted to rotate independent of the drill bit when the rotor and drill bit are in operation.

Abstract: A wellbore motor includes a means for converting flow of fluid in the wellbore into rotational energy. A magnetic gear member is operatively coupled at an input thereof to the means for converting. A wellbore rotary tool is coupled to an output of the magnetic gear member.

Abstract: An orienting apparatus including at least one housing element configured to couple with a drill string; an actuator disposed inside the at least one housing element; a nozzle coupled to the actuator; a torque generator coupled to the actuator and extending axially downward through the at least one housing, wherein the torque generator is configured to rotate in a first direction as it moves downward; a mandrel coupled to the torque generator; and a stroke adjuster at least partially disposed in an upper end of the mandrel, wherein rotation in the first direction is caused by an increase in differential pressure is disclosed.

Abstract: A bearing assembly is situated to conduct axial forces between the general housing and the output shaft by way of an intermediate sleeve that is secured to the output shaft outside the general housing and is axially confined by a bearing assembly secured to the general housing.

Abstract: A locking clutch to selectively transmit torque from a stator of a downhole tool to a rotor of the downhole tool includes at least one locking pawl disposed upon the rotor, wherein the at least one locking pawl comprises a load path, a pivot axis, and a mass center, wherein the at least one locking pawl is biased into an engaged position by a biasing mechanism, wherein the at least one locking pawl transmits force from the stator to the rotor along the load path when in the engaged position, and wherein centrifugal force urges the at least one locking pawl into a disengaged position when the rotor is rotated above a disengagement speed.

Abstract: The invention relates to a drive system, in particular a downhole drilling assembly (10). In the preferred embodiment, a bearing mechanism (14,24) of the assembly (10) is isolated from a gear mechanism (20) of the assembly (10), to prevent failure of the bearing mechanism (14, 24) due to vibration and heat generated by the gear mechanism (20) in use. A lower bearing unit (24) of the bearing mechanism (24) is coupled to the gear mechanism (20) by a shock eliminating coupling assembly (22), which prevents the transmission of shock loads to the gear mechanism (20). Also, the gear mechanism (20) is coupled through a shock eliminating coupling assembly (18) to a turbine (16) and thus to an upper bearing unit (14). Sealing assemblies (60, 116) are provided for the gear mechanism (20) and the upper bearing unit (14) to prevent drilling fluid ingress and consequent damage. The assembly (10) may also carry a torsionally flexible drive shaft (46).

Abstract: In one aspect of the invention, a downhole drill string component has a shaft being axially fixed at a first location to an inner surface of an opening in a tubular body. A mechanism is axially fixed to the inner surface of the opening at a second location and is in mechanical communication with the shaft. The mechanism is adapted to elastically change a length of the shaft and is in communication with a power source. When the mechanism is energized, the length is elastically changed.

Abstract: The invention relates to a drive system, in particular a downhole drilling assembly (10). In the preferred embodiment, a bearing mechanism (14, 24) of the assembly (10) is isolated from a gear mechanism (20) of the assembly (10), to prevent failure of the bearing mechanism (14, 24) due to vibration and heat generated by the gear mechanism (20) in use. A lower bearing unit (24) of the bearing mechanism (24) is coupled to the gear mechanism (20) by a shock eliminating coupling assembly (22), which prevents the transmission of shock loads to the gear mechanism (20). Also, the gear mechanism (20) is coupled through a shock eliminating coupling assembly (18) to a turbine (16) and thus to an upper bearing unit (14). Sealing assemblies (60, 116) are provided for the gear mechanism (20) and the upper bearing unit (14) to prevent drilling fluid ingress and consequent damage. The assembly (10) may also carry a torsionally flexible drive shaft (46).

Abstract: A downhole tractor assembly that is configured for open-hole applications and of a self-aligning nature. The self-aligning nature of the assembly is effectuated through a tractor portion which is rotable about an axis of an elongated body of the assembly independent of a separate centralizing portion of the assembly. That is, the tractor portion, configured for interfacing an open-hole well wall of potentially irregular morphology, is independently rotable so as to maintain a position of substantially optimized driving friction at the interface during tractoring. Maintenance of optimized driving friction in this manner may occur irrespective of the orientation of the centralizing portion of the assembly.

Abstract: An apparatus (10) for use in boring is described, the apparatus including a rotatable drive shaft (12), a cam member (20) and followers (16) for converting rotational motion into reciprocal motion, and a shroud (24) having a cutting edge (26) driven by the cam member and followers. The shroud may be selectively engageable with the cam member and followers, allowing the drive shaft to be removed through the shroud. A fluid circulation arrangement (31), (13) allows air to be injected into loose drilling substrate, so assisting removal of drill cuttings from the boring apparatus. Also described is a drill string incorporating a similar arrangement, allowing the drill string to be reciprocated within a bore. The drill string may further include casing sections, which may have intumescent coatings to allow the sections to be fixed in a wellbore.

Abstract: Apparatuses and methods for generating fluid pressure pulses are disclosed. An example apparatus may include a chamber that can collect fluid and an upstream ported disc coupled to a downstream end of the chamber. The upstream ported disc may rotate about a central axis. The upstream ported disc includes an upstream eccentric port that rotates about the central axis as the upstream ported disc rotates. The example apparatus may include a downstream ported disc coupled to a downstream end of the upstream ported disc such that the downstream ported disc remains substantially rotationally fixed relative to the upstream ported disc. The downstream ported disc includes a downstream eccentric port that may align with the upstream eccentric port to form a passageway for fluid to exit from the chamber to outside of the apparatus, at some time in a rotation cycle of the upstream ported disc.

Abstract: A system for damping vibration in a drill string can include a valve assembly having a supply of a fluid, a first member, and a second member capable of moving in relation to first member in response to vibration of the drill bit. The first and second members define a first and a second chamber for holding the fluid. Fluid can flow between the first and second chambers in response to the movement of the second member in relation to the first member. The valve assembly can also include a coil or a valve for varying a resistance of the fluid to flow between the first and second chambers.

Abstract: A pulling tool for use in the placing of equipment and acquisition of data from pipes and boreholes used in the production of oil and gas. For this purpose the tool is constructed round a central, elongate, cylindrical main element (1) to which there are arranged radially movable links (2), (4) and (5) with chains (3) arranged thereto, running in grooves (11). Radial movement of the links is provided by subjecting a terminal element (9) for the links (5) to an axial movement by means of an actuator (24). The chains (3) are rotated by an electric motor (8) transferring, through the axle (9) connected to the bevel gears (18) and (17), propulsive force to the chain wheel (15) on which the chains (3) are running.

Abstract: A hydraulic motor for use in subterranean drilling operations in which a drive fluid within a first reservoir is forced through the motor by a high pressure working fluid, such as drilling mud, the drive fluid entering a second reservoir upon exiting the motor. Upon a change in valving, the drive fluid in the second reservoir is forced through the motor by the high pressure working and back into the first reservoir.

Abstract: A method and apparatus for boring a hole in the earth including a drill bit assembly including a fluid-powered impact engine contained within a drillpipe sub between an ordinary drillpipe and a modified conventional rotary drill bit. The impact engine is powered by pressurized drilling fluid delivered via the drillpipe which acts on a piston to charge an energy accumulator, preferably in the form of a spring. Periodically, the pressurized drilling fluid in the impact engine is vented, allowing the energy accumulator to rapidly transfer its stored energy to an impact bit which is slidingly housed in a rotary bit to strike and fracture the formation.

Abstract: Systems and methods for directionally drilling a borehole are provided. One system includes a biasing subsystem that is configured to control a tendency of a bottom hole assembly during drilling of the borehole. The system also includes a continuously variable transmission. An output shaft of the continuously variable transmission is coupled to the biasing subsystem such that the continuously variable transmission is configured to control relative rotation of one or more components of the biasing subsystem during the drilling. One method includes controlling a tendency of a bottom hole assembly during drilling of the borehole using a biasing subsystem. The method also includes controlling relative rotation of one or more components of the biasing subsystem using a continuously variable transmission during the drilling. The one or more components are coupled to an output shaft of the continuously variable transmission.

Abstract: The invention relates to gerotor mechanisms for screw downhole motors used for drilling oil and gas wells, to screw pumps for producing oil and pumping fluids and to general purpose screw motors. The profiles of a rotor (3) and stator (1) are outlined in the end cross section thereof in the form of the envelop of the initial contour of a rack-type tool, which is formed by conjugation of circle arcs when said initial contour of the rack-type tool is run without sliding along corresponding tool circles. The arc radii of the circle arcs of the initial contour are calculated according to determined relations. Said invention makes it possible to improve energy characteristics, increase a life service and producibility, to reduce hydromechanical losses and costs.

Abstract: A downhole tractor is provided that includes a motor, at least one rotatable screw powered by the motor, and a chain engageable with the at least one rotatable screw, whereby rotation of the at least one rotatable screw moves the chain.

Abstract: A preferred embodiment of a power-generating device for use in drilling operations comprises a turbine comprising a housing, and a rotor assembly rotatably coupled to the housing so that the rotor assembly rotates in response to the passage of drilling mud therethrough. The power-generating device also comprises one of an alternator and a generator assembly comprising a magnet, a winding, and a housing. The power-generating device further comprises one or more wires for transmitting electrical signals between a first and a second electrical component by way of the power-generating device. The one or more wires are routed through the housing of the turbine and the housing of the one of an alternator and a generator.

Abstract: A downhole tractor is provided that may be used in open or cased wells, and is also designed for use in open holes having a variety of soil/formation consistencies (e.g., soft, firm, rigid, etc.), varying diameters and non-uniform and irregular bore profiles. The tractor may include a track assembly including a plurality of idler wheels and a continuous track rotatably disposed around the idler wheels. A motor may be adapted to rotate the track around the idler wheels. Upper and lower arms may be pivotally connected to opposite ends of the track assembly and pivotally connected to a tractor housing. An actuator arm or link assembly may be provided to impart an outward force to the track assembly to move the track assembly outwardly into an open position and a retracting force to retract the track assembly into a closed position. A rotatable screw may be connected to a second motor, or a rod may be connected to a hydraulic system, to actuate the actuator arm or link assembly.

Abstract: The present invention aims to provide apparatus and method for determining non-circular figure to drill boring holes having a regular N-polygonal cross sections while retaining the advantage of the turning operation. For boring a boring hole (H) with a cross-sectional shape of a regular N-polygon having vertexes of N in number, a boring tool (T) having a cross-sectional shape of a regular (N?1)-polygon which is inscribed on the regular N-polygon of the boring hole is driven to rotate at a certain rotational speed around its center (G) and revolve at a certain revolving speed along a circle (R) which is concentric to the boring hole center (0) and has a certain radius. The boring tool (T) may be replaced with a jet of fluid. A boring tool (T) with a regular (N+1)-polygonal contour may be used instead.

Abstract: An inverted motor with a drilling utensil attached to or integrated as part of an outer motor housing that rotates around a fixed non-rotating shaft or tube. The non-rotating shaft or tube is attached to a fixed base and can extend to the end or past the end of the drilling utensil. A rotary motor is positioned between the outer rotating housing and center fixed shaft and imparts force and motion to the housing and drilling utensil. A channel traverses through the length of the shaft or tube to allow fluids or wires to fully or partially bypass the motor.

Abstract: A drill bit comprises a shank member (31), a bit body (32) provided with cutters (33) and flexible material (35) between the shank (31) and the bit body (32) allowing relative tilting movement therebetween to reduce adverse effects caused by vibration of the bit. In other embodiments, flexible material is provided between the bit body and the cutters. In further embodiments, the flexible material may be provided in a tiltable sub-assembly for incorporation in a drilling above the drill bit. An apparatus for simulating drilling conditions is also provided.

Abstract: An inverted motor with a drilling utensil attached to or integrated as part of an outer motor housing that rotates around a fixed non-rotating shaft or tube. The non-rotating shaft or tube is attached to a fixed base and can extend to the end or past the end of the drilling utensil. A rotary motor is positioned between the outer rotating housing and center fixed shaft and imparts force and motion to the housing and drilling utensil. A channel traverses through the length of the shaft or tube to allow fluids or wires to fully or partially bypass the motor.

Abstract: An apparatus for bursting pipe is preferably adapted to receive rotational energy from the inner member of a dual-member drill string. In a preferred embodiment, an oscillating pipe-bursting member, driven by the interconnected inner members, cuts or bursts a subterranean pipe. In another preferred embodiment, a screw drive moves a pipe-bursting member between an expanded position and a retracted position. In another preferred embodiment, the pipe-bursting member is an arm moveable in response to operation of a screw drive. In yet another preferred embodiment, the pipe-bursting member is hydraulically actuated. This invention increases the efficiency of pipe-bursting operations by utilizing rotation energy generated by a horizontal directional boring system.

Abstract: Systems and methods for drilling a borehole are provided. One system includes a continuously variable transmission. An input shaft of the continuously variable transmission is coupled to a power supply. An output shaft of the continuously variable transmission is coupled to one or more system components such that the continuously variable transmission controls rotation of the one or more system components. One method for drilling a borehole includes supplying power to an input shaft of a continuously variable transmission. The method also includes controlling rotation of one or more system components using the continuously variable transmission during drilling of the borehole. The one or more system components are coupled to an output shaft of the continuously variable transmission. Also provided is a borehole that is drilled by this method.

Abstract: A method and apparatus for controlling fluidic torque in a downhole tool is provided. One or more rotatable components of the downhole tool comprise a deformable material, such as rubber or SMA, selectively deformable in response to the flow of fluid through the downhole tool. The rotatable components may include a rotor and/or a turbine of a generator in the downhole tool. Non-rotatable components, such as the stator of the generator, may also be deformable. The rotor, the stator, and/or turbine may comprise a deformable material capable of selectively deforming in response to the flow of drilling mud through the generator. The desired deformation and/or the desired torque may be controlled by adjusting the parameters of the components.

Abstract: An impactor for use with a directional boring machine having a drill string connectable to the impactor for pulling the impactor through an existing pipeline uses rotation of the drill string to drive an internal striker. The internal striker delivers impacts in the pulling direction to an impactor housing as the impactor housing tows a replacement pipe behind it. The impactor housing is free to move axially in response to impacts from the striker over a limited distance in the pulling direction independently of the replacement pipe and drill string.

Abstract: The down hole motor is a self-contained radial drive unit that is driven by a linear input, which can be supplied from various sources. As linear motion is applied to the input of the tool, drive pins on a drive shaft follow a helical path, converting the linear motion into radial motion at the attached mandrel end. This may then be utilized in various activities such as drilling, boring and obstruction removal. This tool may also be used in conjunction with jarring mechanisms in order to create an impact drilling device, or a percussion motor.

Abstract: The invention relates to well construction and is directed at an oscillation excitation in a pipe string. According to the inventive method, an operating fluid is circulated in the pipe string. An autonomous mechanism for vibrational impact embodied in the form of an element, for instance a hollow ball having a rigid envelop and filled with gas, possessing a positive floatability, covering from 0.85 to 0.95 of a cross-sectional flow area of the pipe string and having an unrestricted degree of freedom. In the second variant, the inventive device comprises a ball support embodied in the form of a transverse beam or a crossbar rigidly connected to a spiral cylindrical spring arranged inside a tube under the ball with the aid of an easy-push fit. The spring force is selected with respect to a calculated axleload dependence on the mass of the ball and on flow strength with a basic flow rate of the operating fluid.

Abstract: The invention relates to a drive system, in particular a downhole drilling assembly (10). In the preferred embodiment, a bearing mechanism (14, 24) of the assembly (10) is isolated from a gear mechanism (20) of the assembly (10), to prevent failure of the bearing mechanism (14, 24) due to vibration and heat generated by the gear mechanism (20) in use. A lower bearing unit (24) of the bearing mechanism (24) is coupled to the gear mechanism (20) by a shock eliminating coupling assembly (22), which prevents the transmission of shock loads to the gear mechanism (20). Also, the gear mechanism (20) is coupled through a shock eliminating coupling assembly (18) to a turbine (16) and thus to an upper bearing unit (14). Sealing assemblies (60, 116) are provided for the gear mechanism (20) and the upper bearing unit (14) to prevent drilling fluid ingress and consequent damage. The assembly (10) may also carry a torsionally flexible drive shaft (46).

Abstract: A garden earth auger operating by repeated twisting its handle is comprised of a drive mechanism at the center of the handle, a gear shaft erected inside the drive mechanism and extending downward to connect to a tooling feeder; a circular yoke inserted onto the gear shaft to control two mobile pawls on one side or both sides of the turning gear shaft to engage or disengage in or from the ratchet for the pawls to drive the ratchet for the tooling feeder to continue circulating for earth excavation in an effort saving fashion while the auger can be easily replaced with a fork or other forms of tooling head to excavate for a pit or scrap soil as desired.

Abstract: An improved method and apparatus for sawing or drilling concrete or like material comprises use of a water-powered pump for introducing a metered amount of a speed-enhancing compound into a stream of water as the water is applied to a masonry saw or core drill during a sawing or drilling operation.

Abstract: A drilling tool having a pilot bit on an end of a main shaft is surrounded by outer shafts having mills on their ends. The bit and mills employ cutters with PDC. The pilot bit rotates in a direction opposite the direction of rotation of the mills. A transmission for rotating a main shaft, on which the pilot bit is mounted, and several secondary shafts, on which the mills are respectively mounted, is carried within a housing using diamond thrust and radial bearings. Power is applied to the main shaft and transmitted to the secondary shafts through diamond hardened gears. Drilling fluid is used to cool and lubricate the bearings and gears.

Abstract: A downhole mud motor is disclosed which has an improved bearing mandrel and a bearing stop to transfer a larger percentage of the weight of the drill string to the bit. Also improve sealing systems for the transmission section and bearing section prevent drilling mud from entering critical components. A piston stop is provided to prevent the piston from damaging any parts as the piston moves under pressure. A compensating pressure disk is placed in the lower housing to prevent pressure from building up in the bearing section. A grooved ball seat is provided in the transmission to allow for greater flow of lubricant around the ball bearings.

Abstract: The apparatus has a housing which is secured to the lower end of a drilling motor body and carries an arbor that is secured to the output shaft of the motor. The arbor has three segments serially connected by gimbals. The upper segment is axially fixed by the bearings of the motor and has a lower end that extends when actuated to push the center segment downward. Axial movement of the center segment actuates a cam to move it laterally. The lower segment extends from the housing as an output shaft. It is arranged to tilt relative to the housing and its upper end is moved laterally by the gimbal connected center segment. The resulting tilt of the rotating axis of the output shaft causes an attached drill head to drill a deflected well bore.

Abstract: A torque limiting device that allows a drill string to rotate relative to the cutting structure of the bit when a predetermined torque is applied between the cutting structure of the drill bit and the drill string. The torque limiting device utilizes a retaining member which restricts rotational movement of a first component of the torque limiting device relative to a second component. When a sufficient torque load is placed on the cutting structure of the drill bit, the retaining member allows rotational movement of the first component relative to the second component and allows the drill string to continue to rotate relative to the cutting structure of the bit until the torque is sufficiently reduced. The torque limiting device may be an integral part of a drill bit, may be a separate device attached between the drill string and the drill bit or between the drill string and a downhole motor, or may be part of a near-bit sub or incorporated in a downhole motor.

Abstract: A downhole hydraulic motor consisting of an outer rim having six or eight lobes on the toothed inner surface, a rotor having four or six lobes respectively on the toothed outer surface as well as a number of planetary gears being constantly engaged with both the outer rim and the rotor and dividing the space between the rim and the rotor into a number of working chambers changing their volume with the rotation of the motor. The working fluid is supplied to the working chambers through channels both in the rotor and the side covers, one of which can slide inside the outer rim to allow adjustment of the gap between the ends of the planetary gears and the side covers.

Abstract: Apparatus for controlling a diamond drill feed cylinder which includes a linear position sensor coupled to the feed cylinder for generating a position signal, a positioning module for generating a feed control signal in dependence upon the position signal, a proportional flow control valve having two hydraulic ports for connecting to the feed cylinder and responsive to the feed control signal for controlling flow rate of the two hydraulic ports, a plurality of operation sensors coupled to the diamond drill for generating operation status signals, a plurality of input modules for receiving the operation status signals and converting them to digital operation status signals and a programmable logic controller connected to the plurality of input modules for modifying the feed control signal in dependence upon the digital operation status signals. The rate of penetration of the diamond drill is controlled by controlling the flow rate applied to the feed cylinder.

Abstract: A downhole motor operated by circulating mud fluid in the wellbore is revealed. The motor has nested rotors and is geared to a bit drive. The motor is a dual-rotor pump that is operated as a motor with mud flow through the rotor housing on end connections. The structures of the rotor housing and the rotors can be made of the same material. An angular offset can be incorporated between the centerline of the output of the motor and the bit drive. In the preferred embodiment, the motor output is through a gear located within a bigger gear connected to the bit so as to provide a speed reducer. The gear on the bit shaft is preferably made of spaced rods to mesh with the gear on the motor output shaft. The drive between the rotors and the bit can accommodate angular offsets of a predetermined amount for directional drilling. The design is compact and can be used to drill wellbores as small as about 2½″ in diameter, or even smaller.

Abstract: An air percussion hammer drill is disclosed for operation in an earthen formation. The air compression hammer mechanism comprises a piston that reciprocates while simultaneously rotating within its housing. A hammer drill bit slidably keyed to the bottom of the piston transfers the impact energy to the formation and rotates during operation independent of an attached drill string.