Abstract: A nested drill bit assembly is disclosed for drilling a wellbore, comprising a parent bit and at least one child bit nested within the parent bit. Each bit in the nested drill bit assembly may be driven by a respective casing that gets cemented in place as part of a drilling with casing system. The parent bit and child bit(s) may be rotated together, with the parent bit and child bit collectively defining a contiguous cutting profile for drilling an initial segment of the wellbore. A driver is then lowered into the casing for connection to the child bit to drill beyond the parent bit. The driver may be configured as a drive bit for drilling through material leftover from a cementing operation prior to connecting to the child bit.

Abstract: The invention relates to a rotary drilling tool and to a method for producing a borehole in the ground, having a base body, a removal device which has at least one hammer unit which comprises a hammer element driven in axially reversing manner, and a discharge line for discharging removed ground material and drilling suspension. According to the invention it is provided that a pumping device is arranged on the base body along the discharge line, and that the pumping device is configured for pumping off the removed ground material with drilling suspension through the discharge line.

Abstract: The present invention relates to a downhole drilling tool system of torque self-balancing and belongs to a technical field of drilling engineering equipment. The drilling tool system consists of an assembly of internal and external drill bits, power components, a pressure adjustment system for internal and external drill bits, a mud circulating system, and an unfreezing system.

Abstract: The invention includes digging equipment having a self-propelled base machine provided with an arm that supports a digging tool. The digging tool is provided with a device for crumbling soil. The digging tool is operatively connected to the base machine through a suspending flexible element that can be wound or unwound by a winch arranged on the base machine. The base machine also includes a main power engine, to actuate all the hydraulic apparatuses of the digging equipment, and a hydraulic system consisting of two independent and separate hydraulic circuits (S; U). A first hydraulic circuit (S) is configured to control and supply the main service apparatuses of the base machine, including a movement apparatus for moving the digging tool. A second hydraulic circuit (U) is configured to control and supply the main digging apparatuses of the digging tool, including at least the actuators of the device for crumbling soil.

Abstract: An apparatus for drilling hole, comprising: a cluster drill of down-the-hole (DTH) percussion hammers having two or more DTH percussion hammers; and a special distributor having rotatable swivels for sourcing compressed air or pressurized fluid from independent supply sources and distributing to the DTH percussion hammers; wherein the DTH percussion hammers are arranged such that one or more circumferential layers of drill bits are formed covering the drilling area; and wherein within each circumferential layer, at least one DTH percussion hammer is supplied with the compressed air or pressurized fluid from an independent supply source that is different from the independent supply source supplying the other DTH percussion hammers.

Abstract: In one aspect, an apparatus for forming a borehole is provided that in one embodiment may include a first milling device configured to rotate at a first rotational speed in a first direction, and a second milling device around the first milling device configured to rotate at a second rotational speed in a second direction, wherein the rotational first speed is greater than the second rotational speed. In another aspect, the first and the second milling devices may be configured to rotate in the same direction at different speeds.

Abstract: An excavator for underground excavating arranged to perform excavating work with low vibration and low noise. A rotary excavator and an underground excavating method are also provided. The excavator (1) for underground excavating comprises a plurality of bits (42a, . . . ) having the outside diameter smaller than that of the excavator body (2) and advancing/retracting to/from the excavating side, piston case members (22b, . . . ) incorporating pistons (61) for applying a hitting force to respective bits (42a, . . . ) by the energy of working fluid, a section (30) for storing the working fluid being fed to respective piston case members (22b, . . . ), working fluid circulation passages (352) for allowing the working fluid being fed to respective piston case members (22b, . . . ) to pass, and a body of rotation (40) provided with a plurality of holes (4a, . . . ) for allowing the fluid storage section (30) to communicate with the circulation openings (3a, . . .

Abstract: The invention relates to a cutter head for a ground cutter machine having at least one cutter motor. Each cutter motor comprises: two hydraulic motors, each comprising a stator and a rotor and having a common axis; a single shaft extending along said common axis and having two ends; two cutter drums mounted to rotate; two transmission assemblies for drivingly connecting each end of the common shaft to one of said cutter drums; and mechanical members for constraining the rotor of each hydraulic motor directly in rotation with the transmission assembly corresponding to the cutter drum that is closer to the hydraulic motor.

Abstract: A drilling device used for drilling into ground, rock or for reaming a predrilled hole includes several hammering bits in a circular shape and equipped with hammers, whereupon they together drill a hole which has a larger diameter. A casing tube can be pulled out of the hole/pushed into the drilled hole. A tubular, rotatable drill rod tube resides in the casing tube. The hammers are located in a circular shape and are each attached to the outer surface of the drill rod tube by joint/hinge attachments lying essentially in the drilling direction. Rotation of the drill rod tube in a first direction turns the hammers and associated bits outwardly from the drill rod tube, and rotation in another direction turns the hammers with their bits inwardly towards the drill rod tube so that they can be pulled away with the drill rod tube from inside the casing tube.

Abstract: The invention relates to apparatus and methods useful for drilling lateral boreholes into a formation surrounding a main borehole. Proposed technique can be used for drilling of laterals which does not require such significant interruptions to deploy the small BHA and is based on the use of a drilling apparatus, comprising a drill collar forming part of a primary drilling assembly and having an outward opening groove in the side thereof, a secondary drilling assembly, comprising a tubular drill string connected at one end to the drill collar, a drilling motor mounted in the drill string, a drill bit mounted at the other end of the drill string and connected to the drilling motor, wherein the secondary drilling assembly is mounted in the drill collar so as to be movable between a first position in which the drill bit is seated in the groove, and a second position in which the bit projects laterally from the groove in the side of the drill collar.

Abstract: A generator (10) is provided for positioning downhole in a drill string (12) to generate power powering one or more downhole tools (16). The generator includes a progressive cavity housing (28) and a progressive cavity rotor (30) which rotates in response to fluid passing through the progressive cavity housing. A restriction (36) in the annulus downstream from the ports controls the fluid flow in the annulus and past the restriction, and thereby the fluid flow through the progressive cavity housing. The generator may provide either hydraulic or electrical power, or both, powering the one or more tools.

Abstract: The invention relates to a foundation construction device for producing trenches in the soil comprising a frame, at least one soil-removing device arranged on the frame and a control device for controlling the foundation construction device in the trench, wherein the control device has at least one control body which can be adjusted between an inoperative position and a projecting control position in order to rest on a wall of the trench. Provision is made for the control body to be adjusted into a first projecting control position on a first side of the frame or into a second projecting control position on a second side of the frame that lies opposite the first side of the frame.

Abstract: The invention relates to a cutter head for an excavator machine having at least one cutter motor, each cutter motor comprising: a fastener plate; a mounting structure comprising an end portion and a mounting assembly; a single hydraulic motor mounted in said mounting assembly and having an outlet shaft presenting two ends, said motor and the end portion of the mounting structure being offset in a direction that is orthogonal to said fastener plate; a plurality of conduits formed in the thickness of the fastener plate; and a plurality of ducts formed in said end portion of the mounting structure to connect the hydraulic motor to said conduits.

Abstract: A cutting device for sinking a cut hole in the ground, having a support on which are mounted in rotary manner about in each case one cutting wheel rotation axis at least two cutting wheels, at least one cutting wheel drive mechanism for the rotary driving of the cutting wheels on the support and a drive mechanism for the rotary driving of the support together with the cutting wheels about a support rotation axis directed roughly parallel to the sinking direction. A method for producing a cut hole in the ground using the cutting device.

Abstract: The invention relates to a device for making a trench wall in the soil comprising a frame, at least one lower cutting/mixing wheel arranged at the bottom of the frame, at least one further, upper cutting/mixing wheel arranged at the top of the frame, wherein the frame is designed in an intermediate portion between the upper cutting/mixing wheel and the lower cutting/mixing wheel with a smaller cross section with respect to the cutting cross section of the at least one lower cutting/mixing wheel. The invention further relates to a method for making a trench in the soil by means of such a device.

Abstract: The invention relates to a method and device for the drilling, in particular the percussive drilling or rotary percussive drilling of holes (9) in the ground or in rock, a bore hole (9) being formed by a drill bit (1) that is mounted on a drill pipe (3), by a percussive and/or rotary movement. Several drill points (2), which can be coupled to the drill pipe (3) and driven independently of one another, are provided on the drill bit (1). According to the invention, the drill points (2) can be uncoupled from their rigid coupling to the drill pipe (3) upon completion of the drilling process and can be displaced towards the centre of the bore hole (9), thus permitting the entire drill bit (1) together with the drill points (2) and the drill pipe (3) to be simply and reliably removed upon completion of the bore hole (9).

Abstract: A downhole device processes particles entrained in a drilling fluid returning up a wellbore. In one embodiment, the device includes a housing having at least one cutting surface formed in a chamber of a housing. A cutting head disposed in the chamber crushes or comminutes the particles entrained in the drilling fluid to a predetermined size. The device is disposed in the wellbore and processes the entrained particles before they enter a selected wellbore device such as a pump. In certain embodiments, the housing has at least two chambers, wherein the entrained particles are reduced to a first predetermined size in the first chamber, a second predetermined size in the second chamber, etc. Also, the housing can include an operator that generates an energy field that reduces the size of the particles entrained in the drilling fluid to a first predetermined size when the particles flow through the energy field.

Abstract: Three air hammers are housed and arranged in a hammer case, and have bits at their respective ends. Each of the air hammers can be activated independently. In a normal excavation, the earth is excavated by activating all the air hammers. When correcting an excavating direction, only an air hammer positioned in the correct direction is activated first so that the earth in the correct direction is excavated in a predetermined amount. Next, all the air hammers are activated to excavate the earth. Thereby, a leading hammer can direct the excavation toward the correct direction, and thus the excavating direction is corrected.

Abstract: A core barrel has a plurality of pneumatic downhole hammer drills disposed around the perimeter of its working end for drilling piles in the ground for use in foundations, secant piles, and the like. The core barrel includes a slurry port and an air port at its top end for admitting a drilling slurry and pressurized air, which is used in driving the hammer drills and flushing cuttings from an annular kerf during drilling. A plurality of generally parallel plates form the top of the core barrel and define an air channel and a slurry channel for delivering air and slurry to the core barrel wall, where they flow freely or via conduits toward the hammer drills at the working end of the core barrel. The hammer-type core barrel is used to construct piles by first drilling an annular kerf in the ground. Circulating drilling fluid cools the working end of the hammer drills elements and washes cuttings from the kerf during drilling.

Abstract: A rotating tool for milling or drilling in a well bore, having one or more rotating cutting structures, with each cutting structure rotating about its own axis, and with the cutting structures rotating about the axis of the tool. The rotational axis of the tool is offset from the axis of at least one cutting structure, with the axis of the tool passing through that cutting structure. This ensures that the cutting structure which spans the axis of the tool rotates independently of the tool, to prevent the existence of a zero velocity point on the cutting face of the tool.

Abstract: A core barrel has a plurality of pneumatic downhole hammer drills disposed around the perimeter of its working end for drilling piles in the ground for use in foundations, secant piles, and the like. The core barrel includes a slurry port and an air port at its top end for admitting a drilling slurry and pressurized air, which is used in driving the hammer drills and flushing cuttings from an annular kerf during drilling. A plurality of generally parallel plates form the top of the core barrel and define an air channel and a slurry channel for delivering air and slurry to the core barrel wall, where they flow freely or via conduits toward the hammer drills at the working end of the core barrel. The hammer-type core barrel is used to construct piles by first drilling an annular kerf in the ground. Circulating drilling fluid cools the working end of the hammer drills elements and washes cuttings from the kerf during drilling.

Abstract: Three air hammers are housed and arranged in a hammer case, and have bits at their respective ends. Each of the air hammers can be activated independently. In a normal excavation, the earth is excavated by activating all the air hammers. When correcting an excavating direction, only an air hammer positioned in the correct direction is activated first so that the earth in the correct direction is excavated in a predetermined amount. Next, all the air hammers are activated to excavate the earth. Thereby, a leading hammer can direct the excavation toward the correct direction, and thus the excavating direction is corrected.

Abstract: A core barrel has a plurality of pneumatic downhole hammer drills disposed around the perimeter of its working end for drilling piles in the ground for use in foundations, secant piles, and the like. The core barrel includes a slurry port and an air port at its top end for admitting a drilling slurry and pressurized air, which is used in driving the hammer drills and flushing cuttings from an annular kerf during drilling. A plurality of generally parallel plates form the top of the core barrel and define an air channel and a slurry channel for delivering air and slurry to the core barrel wall, where they flow freely or via conduits toward the hammer drills at the working end of the core barrel. The hammer-type core barrel is used to construct piles by first drilling an annular kerf in the ground. Circulating drilling fluid cools the working end of the hammer drills elements and washes cuttings from the kerf during drilling.

Abstract: A conveyance apparatus for conveying at least one logging tool through an earth formation traversed by a horizontal or highly deviated borehole. The conveyance apparatus comprises a pair of arcuate-shaped cams pivotally mounted to a support member, a spring member for biasing the arcuate surface of each cam into contact with the borehole wall, and actuators operatively connected to each cam. A logging tool is attached to the conveyance apparatus. When either actuator is activated in a first direction, the cam connected to the activated actuator is linearly displaced forward and the arcuate surface of the cam slides along the borehole wall. When either actuator is activated in a second direction, the activated actuator pulls the connected cam backwards and the spring member thereby urges the arcuate surface of the cam to lock against the borehole wall.

Abstract: A conveyance apparatus for conveying at least one logging tool through an earth formation traversed by a horizontal or highly deviated borehole is disclosed. The conveyance apparatus comprises a pair of arcuate-shaped cams pivotally mounted to a support member, means for biasing the arcuate surface of each cam into contact with the borehole wall, and actuators operatively connected to each cam. A logging tool is attached to the conveyance apparatus. When either actuator is activated in a first direction, the cam connected to the activated actuator is linearly displaced forward and the arcuate surface of the cam slides along the borehole wall. When either actuator is activated in a second direction, the activated actuator pulls the connected cam backwards and the biasing means thereby urges the arcuate surface of the cam to lock against the borehole wall.

Abstract: A chuck and drill bit combination for insertion into a front end of a percussive, down the hole drill forming a part of a cluster drill assembly, for selectively engaging and disengaging the chuck and drill bit during drilling operations includes the bit and chuck each having splines and grooves adapted to overlap and engage each other in a first stop position and further adapted to disengage from each other in a second stop position, whereby the bit is restrained from rotational movement but capable of axial movement in the first stop position and capable of both axial and rotational movement in the second stop position, to provide automatic indexing of the bit so as to position the bit's gage drilling buttons in a preferred position outboard of the drill centerline, to maintain maximum borehole diameter.

Abstract: A cluster drill includes a first plate portion and a second plate portion. The first plate portion extends parallel to the second plate portion and is rigidly affixed to the second plate portion. At least one first and second plate aperture is formed in the first and second plate, respectively. At least one modular retainer unit, to be mounted within the first and second plate apertures, retains a first and second portion of a rock drill apparatus. A cannister affixes the first plate portion relative to the second plate portion. The cannister may be either cylindrical or contain protuberances to accommodate the modular retainer unit. A drill bit lock restricts motion between the a drill bit and the second plate when desired.

Abstract: A drill head is disclosed, for use to drill a hole in a front of hard material such as rock, which comprises a main body acting at a central support, an upwardly projecting spindle secured on top of the main body, the spindle having a vertical axis, a fixation head on top of the spindle for detachably connecting it to a drill shaft operable in use to rotate the drill head about the vertical axis of the spindle and to pull it up toward the front hard material to be drilled, and at least two impact hammers mounted onto the main body in such a manner as to fragment, in use the hard material of the front along at least one circular path centered onto the vertical axis, each impact hammer having a hollow casing, a pneumatically-operated, impact generating assembly enclosed within the casing, and a drill bit actuated by the impact-generating assembly.

Abstract: The invention relates to a motor-driven milling machine construction for cutting trenches in the ground, in which there are two rotating semi-drums with cutting tools at their periphery. The drums are mounted on a central support. The sole function of the motor is to transmit a rotational torque to the semi-drums without transmitting any other forces. The stress exerted on the cutting tools is directly transmitted to the central support without going through the motor frame.

Abstract: A percussion drilling apparatus for drilling bore holes into subterranean formation in which a plurality of drill rods are arranged in concentric rows in a drill bit housing, each rod having an impact tooth at its lower ends and the rods arranged either to converge inwardly adjacent to the center of the housing or to diverge outwardly at progressively increased angles in each row toward the outermost row. The impact teeth are fired sequentially by concentric combustion chambers arranged above the drill rods and where the pattern and rate of firing can be controlled by cam operated intake and exhaust valves associated with the combustion chambers. The drill bit housing is arranged at the lower end of the drill string with an umbilical cord which carries all necessary cables and lines between the surface controls and the drill bit housing for the purpose of controlling combustion in each chamber and of carrying away the cuttings as the drilling operation proceeds.

Abstract: A rock drilling appartatus wherein the rock drill is a cluster of independent rock drills arranged in a circular pattern about a central axis for rotation. The cluster drill is drawn into a hole to be drilled by a drill string in a previously drilled smaller diameter hole. The drill string provides pressure fluid to operate the cluster drill and rotation as well as the tractive force to draw the cluster drill into the hole to form a large diameter straight drilled hole. Pressure fluid and rock cuttings exit the larger diameter hole and discharge of rock particles is further aided by use of a trailing auger rotated by the cluster drill. A particular application of this device is in the production of horizontal bored holes of moderate diameter under, for example, roadways, foundations, and the like. The drill string acting as a centering device produces a straight hole in difficult rock formations.

Abstract: A milling machine for digging trenches in the earth, of the type comprising at least one substantially vertical support plate on both sides of which two milling drums are mounted for rotation about an axis substantially perpendicular to the plate, each of the drums carrying, on the one of its edges which is adjacent to the support plate, at least one tool which projects laterally with respect to this edge, and the support plate including opposite the trajectory of said tools, circular channels coaxial with the drums, through which the ends of these tools pass when the drums turn. The projecting tools of one of the drums redisposed at a distance from the axis which is different from the distance to the axis from the projecting tools of the other drum, the channels having, correspondingly, different radii.

Abstract: A milling engine for cutting trenches in ground or soil provided with at least one vertical support plate on both sides of which milling drums are supported for rotation about an axis perpendicular to said plate. One or more movable fingers are mounted on the lower edge of the plate for oscillating movement aobut the central axis of the plate during the rotation of the drums to remove a web of soil beneath the plate. Oscillation of the fingers is effected through camming surfaces formed on opposing inner ends of the drums which camming surfaces cooperate with a cam disposed at the inner ends of said movable fingers.

Abstract: A drilling machine for digging trenches in the ground of the type comprising at least one substantially vertical support plate (3) on which are mounted two drilling drums (2) one one each side of it for rotation about an axis (4) substantially perpendicular to the plate.The downwardly facing edge surfaces of said plate have portions (13) inclined relative to the direction perpendicular to said plate.

Abstract: The invention relates to a drill bit which includes a drive arrangement having two opposed drive shafts which are transverse to the drill rod axis, mechanism for driving the shafts and a rock comminuting cutter which is eccentrically mounted on each of the shafts.

Abstract: A shaft drilling machine comprises a drill head carrying drill tools thereon, a device for guiding the drill head in a shaft, a device for advancing the drill head in the shaft, and drive aggregates which are lowered into the shaft together with the drill head and driving the latter. A sluice for providing a rinsing fluid is arranged in a pilot drill. A rinsing conduit and an ascending conduit for extracting from the shaft a drilled material-rinsing fluid mixture generated during the drilling operation are connected to the sluice which is formed as a bucket wheel.

Abstract: Disclosed is a new method of construction for multiple or gang down hole rock drills. A rigid mounting cylinder with alignment and securing means for the individual drills is provided. The cylinder further serves to attach the multiple drills to a single drill string which supplies air to the individual drills. The cylinder further facilitates rock chip removal by filling all but the peripheral annulus which forms the exit channel for exhaust air.

Abstract: A trench excavator capable of excavating a trench of a rectangular section suitable for formation of an underground diaphragm wall. The underground diaphragm walls are now applied as underground structures replacing caissons, rigid foundations for multistory or tower like buildings, underground tanks and the like. In the trench excavator according to the invention, a pair of drum cutters and a ring cutter interposed therebetween form one unit and a plurality of such units are arranged parallel to one another, whereby an unexcavated portion produced between the drum cutters can be cut out by the ring cutter, leaving no unexcavated portion.

Abstract: A slotted wall milling cutter for producing a slotted wall in the ground has a drive motor fixed to the cutter frame and a gear means positioned between the drive motor and two cutting wheel gears and which is partly arranged in recesses of a bearing bracket. The cutting wheel gear is constructed as a multistage planetary gear. A particularly high torque is made available on the cutting wheels with this arrangement. In addition, the cutting wheels can be constructed with a very high effective cutting width compared with the total slot width.

Abstract: The invention relates to a device for the production of circular boreholes in soil, of the type incorporating a pair of bits driven in rotation in opposite directions, the said bits being equipped with teeth or similar members for breaking up the soil.It comprises a first pair of bits (6) which are equipped with teeth, rotating in opposite directions around two parallel axes, each of these bits having the external shape of a volume of revolution the generatrix of which consists of a circular arc corresponding to the circular cross-section of the borehole which it is intended to dig, and a second pair of bits (7) situated above the first, and the bits (14a,14b) of which have the same structural characteristics as the bits of the first pair but whose axes of rotation are offset relative to the latter.

Abstract: A drilling attachment for a utility truck designed for digging pole holes for ordinary utility and telephone poles is disclosed herein. The attachment is intended to replace the auger portion of a conventional auger digger when it is necessary to drill through rock or other hard materials. The excavating method contemplated employs a three step process. First, a deep kerf is cut into the rock by a plurality of drill bits that are independently driven in a rotary/percussive manner while being rotated about the circumference of the kerf. The dust and rock fragments generated by this process are removed from the kerf by an air flushing/vacuum system, that also serves to cool the drill bits. Second, a hydraulic piston is inserted into the kerf and expanded, thereby applying a lateral force to the base of the resultant core causing it to break away from the surrounding rock. Finally an expandable plug is inserted into a pilot hole located at the center of the core.

Abstract: A device and process for sinking vertical wells. A pair of rotary digging heads have horizontal axes mounted on supports for movement of such axes towards and away from each other between a central position close to the axis of a well and a peripheral position adjoining the wall of the well being formed. The different heads are spaced apart so that the horizontal components of the reactions resulting from them cancel each other out. A process for using the device to form a well wherein the heads are initially close together and progressively move apart as the well is formed.

Abstract: The invention disclosed herein is a mining machine with an adjustable hood-scoop assembly. The machine provides a means to remove coal from the face of a seam and extract the removed coal to a position removed from the mining area utilizing a vacuum system. The instant mining machine encloses the total face of the mine seam and acts to remove all solid and gaseous material from the mining area. Use of this apparatus in the mining of coal will provide better insurance for a healthy methane-free environment for the miner. The hood-scoop assembly is constructed to provide both horizontal and vertical moving plates so as to encompass totally the area contacted by the coal removal means, such as a multitude of air hammers. The machine is both braced and made mobile by means of vertical hydraulic jacks. Hydraulic cylinder means on the hood-scoop assembly are provided with specific trackways to insure four-way movement of the adjustable plates as shown in FIGS. 1, 2, 4 and 7.

Abstract: A method for drilling hard material such as rock by fragmenting the rock by impact in selected spaced-apart areas and simultaneously fragmenting the rock by shear between the selected areas. The invention also covers a drill head with particularly arranged impact hammers for carrying out the method, and a drill unit incorporating the drill head.

Abstract: Minerals, in particular coal, that have been deposited in layers or along seams in the earth can be mined utilizing a large diameter bore hole drilling equipment. With the drilling equipment stationed on the surface of the earth, a drilling member is drilled down into the earth along the seam of the mineral deposit. If the mineral deposit extends at an angle to the earth, i.e. less than 90.degree., the drilling operation is conducted so as to drill at a similar angle to the earth. As the mineral deposits are broken up during the drilling operation, the broken fragments are removed from the drilled hole. After drilling has occurred for a certain distance in a forward direction, a creeping effect is induced in portions of the side walls of the drilled hole. The drilling member is then retracted from the drilled hole in such a manner so as to drill out any mineral fragments in the hole of the drilling member. These mineral fragments are then removed from the hole as the drilling member is retracted.

Abstract: Method and apparatus for gaining access to an underground chamber is disclosed to utilize a pressurized pipe casing which defines a conduit for introducing compressed air to a drill, which drill is utilized to bore a rescue hole to an area of entrapped miners. Thereafter, access is gained to the area of entrapment and the drill pipe is utilized as casing defining a rescue shaft for providing ingress of rescue personnel and egress of entrapped miners.

Abstract: An undercutter comprising a slotted tubular body in which is mounted an extendable and retractable cutting head for undercutting a bore into which the tubular body is positioned and rotated. The cutting head includes a fluid-operated reciprocally movable piston, the reciprocating rate of which is determined by an annular liner positioned between the outer wall of the piston body and the inner wall of the piston cavity.

Abstract: The invention herein relates to an undercutting device which is provided with a substantially tubular body adapted to be placed within a parallel-sided hole. A rotary percussion head is provided at one end of the body and has one or more cutting tools which extend radially therefrom at an obtuse angle and which cutting tools are adapted to cut outwardly from the radius of the body, means are provided for rotating the head about the axis of the body and for operating the percussion head at one predetermined depth in the hole so that the cutting tools may act on the wall of the parallel-sided hole.

Abstract: A multiple in-hole motor and drill combination is disclosed for drilling a large diameter earth bore. The motor assembly is supported on a fluid circulating pipestring, and includes a plurality of circumferentially spaced longitudinally extended in-hole motor and drill combinations to which motor fluid is supplied through the running in pipestring, the motor fluid then passing through the rotary drill bit driven by the motor and returning to the top of the well. The plural in-hole motor drill assemblies are rotated during the drilling operation. A hydraulic drive motor powered by a separate fluid source is employed to rotate a housing to drive the multiple motor drill assemblies rotatably about the central support. The lower end of the multiple motor drill assembly supports a number of weights to apply drilling weight to the bits.

Abstract: Casing is run into a well bore hole on a running pipe string. Fluid motor and drill apparatus is supported in the casing, with the drill extending below the lower end of the casing to drill the bore hole in advance of the casing. For subsea drilling operations, the casing is suspended from a riser housing which lands on a subsea base, and the running pipe is released from the riser housing to enable retrieval of the motor and drill assembly. Plural motors are employed for drilling large holes.