Abstract: A soft excavator (10, 90, 110, 130) is disclosed which utilizes a jet of high velocity fluid flow such as air or water flow, preferably supersonic, through a nozzle (48, 92, 112) to excavate a material, such as the ground. A second passage for air flow is provided which is directed by an evacuator skirt (52, 102) in a direction along the excavator generally opposite the direction of discharge of the high velocity excavating flow to entrain the material excavated for disposal.

Abstract: An apparatus and method are provided for enhancing fatigue properties of subterranean well drill pipe immediate the area of securement to a tool joint by providing a multi-ramp upset series on the drill pipe which, in effect, enhances fatigue resistance properties of the pipe by increasing the wall thickness on the end of the drill pipe conduit to a greater length than that found on prior art, conventional upsets adjacent the drill pipe. The increased length of this upset configuration provides a smoother transition from the thick upset adjacent the tool joint down to the thin drill pipe body.

Abstract: A pipe body is provided having an upset portion and connecting to a tool joint to form a relatively rigid region. A stress relief groove is provided in this relatively rigid region of the tubular member to limit stress applied in the pipe body adjacent the upset portion by rotation of the pipe while the pipe is in an arcuate portion of a well bore. The stress relief groove is designed to increase flexibility of this relatively rigid region while providing that the anticipated stress to be applied in the relatively rigid section is less than the endurance limit in the locus of the stress relief groove.

Abstract: An adjustable bent housing consisting of three tubular members arranged in end to end relation. Each of the tubular members has an interior bore. A first tubular member has a first axis. A second tubular member has a second axis. A central tubular member is centrally disposed between the first tubular member and the second tubular member and has a third axis. An internal tubular member extends into and engages the interior bores of the three tubular members thereby maintaining the tubular members in end to end relation.

Abstract: The invention relates to improvement in well drilling tools to prevent drilling fluids and solid particles present in a subterranean location from adhering to drilling equipment. A nickel-phosphorus coating is deposited by an electroless plating process on the entire surface of the tool, so as to substantially reduce porosity of the tool and prevent penetration of the foreign matter into the ferrous core of the tool.

Abstract: A composite drill pipe has a fiber reinforced synthetic tube with a leading end and a trailing end spaced axially from the leading end, with the leading end of the tube being engageable with a bit for drilling a bore through the earth when a force is applied to the trailing end of the tube. Hardened steel fittings are attached to the opposite tube ends and have interengageable threaded portions for joining a plurality of serially arranged drill pipes and forming a flexible drilling string of desired length. Radial holes are drilled around the circumference of the tube ends and into the steel fittings, and stainless steel dowel pins are press fit into the holes to provide a mechanical lock between the composite tube and the fittings. A steel sleeve is placed over the is bonded to the outer surface of the tube.

Abstract: Various steel, downhole tools and components of a drill string, including, as examples, a PDC drill bit, a rotary rock bit, a cross-over sub, a stabilizer, a reamer, a hole enlarger and a coring bit, are selectively treated to cause certain of their parts to be electro-negative with respect to steel, and certain other parts to either have the same electro-negativity as steel, or to be treated to be electro-positive with respect to steel.

Abstract: A reversible casing for a down-the-hole drill has a predetermined snap ring groove length centered between the casing ends, based upon the casing bore, the snap ring groove depth and the snap ring body length, whereby a snap ring will be retained in the snap ring groove, while permitting lengthwise movement of the snap ring during reverse orientation of the casing.

Abstract: A loose crown underreamer apparatus (10) for boring into earth and other materials includes a crown (28) loosely coupled to a bit shank (12). The loose coupling mechanism (34) employed in the present invention reduces the occurrence of friction welds occurring between crown (28) and bit shank (12). Coupling mechanism (34) employed in the present invention includes a plurality of deformable polyurethane retainer balls (36) disposed in shank sockets (38) and corresponding crown sockets (40). Coupling mechanism (34) employed in the present invention allows for crown (28) to be uncoupled and re-coupled to bit shank (12) at will.

Abstract: The pipe coupling in accordance with the present invention broadly includes an elongated female member having structure defining a bore spanning the length thereof, a first hollow elongated male member having an end portion non-rotatably affixed within a portion of the bore, a second elongated male member slidably engagable within the remaining portion of the bore, a lock pin slidably engagable through aligned apertures in the female and second male members, and a pliable gasket for placement between the first and second male members. The second male member also includes structure defining a passage spanning its length and presenting an inlet and an outlet wherein the passage diverges into two passages on the inlet side of the aperture and converges back into one passage on the outlet side of the aperture.

Abstract: A drill unit (12) is disclosed which uses slides (18, 20) mounted on the saver-sub (16) of the drill unit to lock the drill pipe (14) to the saver-sub (16) for joint rotation. Dogs (32) are engaged with flats (50) on the drill pipe by moving an outer collar (42) over the end of the drill pipe. The outer collar holds the dogs within the flats to ensure joint rotation between the saver-sub and the drill pipe. The outer collar (42) can be retracted away from the drill pipe to move the dogs out of engagement with the flats and move the slides (18, 20) to the retracted position.

Abstract: A drill section includes a hollow tube having a reduced portion of a box disposed in each end. Each box is welded to the hollow tube by a circumferential weld extending around an angled portion connecting the reduced portion of the box to a portion of the box having the same outer diameter as the hollow tube. There preferably is welding of the reduced portion of the box to the hollow tube through three equally angularly spaced slots at each end of the hollow tube. A break out ring is disposed on a threaded pin of a tool joint between the box, which has a threaded recess extending inwardly from its end to receive the threaded pin to attach the tool joint to the box, and an annular surface of the tool joint. A protective sleeve on the box has an annular end surface at the same angle to its longitudinal axis as an annular end surface of a collar, which is welded to the box, and held thereagainst by the tool joint attached to the box.

Abstract: The drilling system of this invention provides a drill mast mounted on a turntable. The turntable may be mounted on any type of undercarriage or carrier. The drill mast can be positioned around the perimeter of the turntable, it can be positioned near to, or away from, the turntable. The drill mast is carried on a trunnion mounting and can be oriented along Y and Z axis' with respect to the turntable X axis for drilling angle holes. A pipe joint breaker assembly is provided adjacent the lower end of the drilling mast. This assembly can accommodate different size pipe diameters. The drilling systems of this invention is specially adapted to reverse-circulation sample drilling employing a down-the-hole hammer drill. The drilling head configuration provides for simultaneous feeding into a multi-walled drill string of drilling mud, compressed air into the drill string to operate the hammer drill and to feed the hammer drill bit head, and withdrawing of sample-containing return air.

Abstract: Drill string component for top hammer drilling comprising a rod (13) surrounded by a tube packet (4,5). The rod is provided with a thickened section (14) for cooperation with a diameter reduction (15) in the tube packet which at upwards drilling is situated below the section (14). Through this flushing liquid is prevented from flowing out of the drill string when the drill string is extended.

Abstract: A drilling device including a hydraulically actuated drive for exerting an oscillatory action on the drive including the drive element, inserting device for hoses conducting a working medium to a pressure-actuated hammer mounted on a front end of the rod and the flushing head at an oscillation angle ranging between 180.degree.-360.degree.. The flushing head is fixed oscilatorily with the drive member and both are swingable about a swivelling axis out of an alignment with the slide and the drive member is formed with a recess for selectively attaching a respective plug-in rod end of the drill rod, so that a torque produced by the drive is transmitted to the drill rod by the drive unit upon interlocking of the flushing head and rod.

Abstract: The drilling system of this invention is specifically adapted to reverse-circulation sample drilling employing a downhole hammer drill. The drilling head configuration provides for simultaneous feeding into a multi-walled drill string with drilling mud, compressed air to operate the hammer drill, to feed the hammer drill head and withdrawing of the return air. The system includes a triple-walled drill rod especially adapted for downhole hammer drilling that eliminates the need for a separate drive casing string.

Abstract: An apparatus for cleaning layers of earth that contain noxious material via a cleaning medium that takes up the noxious material and is introduced into the layers of earth via a drilling tube. The cleaning medium is extracted by suction from the layers of earth and is subsequently processed. To achieve a precise cleaning on the spot in a continuous manner without the necessity for excavating the earth, the apparatus comprises a chamber that surrounds the drilling tube. The chamber can be lowered into the ground either together with or separately from the drilling tube. After termination of the cleaning process, at least parts of chambers used therefor are removed from the ground and shifted to a region that has not yet been cleaned, resulting in an advancement of the cleaning process in a horizontal direction. A sludge mixture can also be pumped from the chamber into a cleaning unit, with the clean, recovered earth again being introduced into the chamber.

Abstract: A drill rod having an inner tube extending through the rod. The rod and the tube form a dead zone that reduces the time necesssary to compress air within the rod. By presenting a smaller internal cross-sectional flow area within the rod and, as a consequence throughout the drill string, the drill hammer disposed at the bottom of the hole will operate more efficiently.

Abstract: An apparatus is disclosed for use in a drill string 10 to prevent separation of a lower tubular member 16 from an upper tubular member 15 by a rotational force applied from a down-hole motor 22. The down-hole motor 22 is rotated by drilling fluid pumped from the surface, through a passage formed within the drill string 10, and into the down-hole motor 22. A valve 36 is positioned in the passage in the drill string 10 and has a first operating position adapted for passing the drilling fluid to the down-hole motor 22, and a second operating position adapted for substantially blocking the drilling fluid from being delivered through the down-hole motor 22. The value is of a two piece construction, having a first body 44 connected to an upper tubular section 14 and a second body 46 connected to the down-hole motor 22.

Abstract: A driver sub and a case for enclosing a piston chamber of a percussion drill are threadedly connected by respective identical male and female screw threads. Each of the identical male and female screw threads includes a root portion, the shape of which is defined by portions of two axially overlapping ellipses interconnected by a flat.

Abstract: Apparatus for drilling horizontal drain holes from within existing wellbores is comprised of a flexible rotary drillstring made from a plurality of arcuate elements tightly drawn along a central cable, and of driving and redirecting apparatus to rotate and deflect the drillstring. The elements, engaged to the cable, provide a stiff drillstring which, combined with the rotary drive at the well bottom, permits extensive drilling. A deflection block, precisely fitted to the drillstring and to other apparatus requirements, enables the drilling functions. An alternate drillstring has cylindrical interlocking elements with internal alignment means.

Abstract: A tool actuator which comprises a casing containing a pipe, which is movable from a locking position to an unlocking position, under the action of a fluid pumped through the casing. When the pipe is in the locking position it locks a mandrel in an activating or deactivating position. When the pipe is in the unlocking position it does not contact the mandrel which is therefore free to move between the activating and a deactivating positions. The fluid pressure will be different for each of the positions of the pipe and mandrel and consequently their position can be monitored by monitoring the pressure of the fluid, for a given fluid flow rate.

Abstract: An adjustable bent sub for a down hole drill is disclosed consisting of a hollow housing and a hollow mandrel shaped to fit within the housing. A jam nut is positioned on the end of the mandrel to retain it within the housing by abutting a shoulder provided on the inner surface of the housing. A 1 degree off-normal face is machined on the shoulder and on the abutting face of the jam nut. By positioning the mandrel/jam nut assembly at different angular positions with respect to the housing, a linear deviation of 0 to 2 degrees is possible through the length of the sub.

Abstract: The invention relates to the drilling of a hole for the study of the underground. The roto-percussion head acts on the drilling tube of which the base carries a cutter. The cutter is integral with the sleeve inside which drilling water is injected. The water and the rock debris go up and out through the evacuation opening. Application to the reverse flow drilling allowing to extract at the evacuation opening cores or rock debris which go up inside the axial tube as soon as they are taken without any risk of being contaminated by the previously traversed layers of ground.

Abstract: The present invention discloses a universal, adjustable angle, pipe joint which permits a wide variety of possible adjustments with simple means in deep well drilling technology. In principle, the pipe joint disclosed in this invention can be readily used for joining articles of all types which include tubular, pipe-like, projections.

Abstract: A progressive cavity drilling apparatus which includes a drill bit, a drill bit driving shaft have a hollow bore formed therein and a progressive cavity drive train for driving the drilling shaft. A flow restrictor is provided to cause fluid leaving the progressive cavity drive train to enter the interior of the hollow drilling shaft and then to be exited therefrom through nozzles formed in the drill bit. The flow restrictor includes a groove to allow a small amount of fluid to flow in a path winding around the circumference of the flow restrictor and into a bearing assembly located below the flow restrictor. Because the flow path winds around the circumference of the flow restrictor, it is significantly longer than a straight longitudinal flow path. Consequently, the velocity of the high pressure fliud through the flow path is significantly reduced thus minimizing erosion and wear of the flow restrictor.

Abstract: A method and apparatus for creating an underground bore hole employing a steerable boring head at the end of a remotely driven drill string. The boring head, preformed at an angle to the longitudinal axis of the trailing pipe string to bore along a curvilinear path is straightened by increasing the pressure of the fluid within the drill string above a predetermined range to enable drilling along a linear path. Subsequent reduction of the fluid pressure to normal drilling pressure returns the boring head to its former state along a resumption of a curvilinear drill path.

Abstract: A percussion drill includes a reciprocating piston surrounded by a cylindrical casing. Disposed at opposite ends of the cylindrical casing are replaceable hollow cylindrical wear sleeves. The wear sleeves are mounted within recesses formed in the outer surface of the casing. Each wear sleeve has a thickness equal to the depth of its respective recess. A longitudinal inner end of each wear sleeve is spaced longitudinally from an end surface of the recess, and a flexible seal is situated between those opposing ends. The wear sleeves can be replaced after being worn by the abrasive environment encountered in the hole being drilled. The wear sleeves may be formed of a more wear resistant material than the casing.

Abstract: An oil tool release joint with a top sub that has a pin end which inserts into an opening in a bottom sub provides an alternative remote tool for separating pipe string segments after rotation. The subs are held together by shear pins which are wedged through holes in the bottom sub into recesses in the top sub. The bottom sub has uphole extending splines that engage slots in the top sub when the subs are connected. The splines and slots translate rotational motion from one sub to the other. The joint releases upon the application of a force sufficient to shear the shear pins either by hydraulic pressure in the drill string, an upward pull on the top sub or both. A guide ring encircles the uphole ends of the splines to guide material into the bottom sub when the joint is separated.

Abstract: A drill pipe for combination rotary-vibratory drills. The pipe includes an elongated pipe member and a connector for connecting the drill pipe to another drill pipe. The connector includes a threaded member at one end of the pipe member. The connector and pipe member have overlapping portions. The portion of one of the members has a plurality of circumferentially spaced-apart slots which are generally aligned axially with the pipe member, and welds along the slots securing the pipe member and connection member together.

Abstract: A drilling system comprises a drill string (1) incorporating inbuilt tubular conductors (25), a mud supply passage, and passages for protective or other fluids. The drill string can be advanced by selectively actuable pistons (51,60) exposed to drilling mud flow, by electrically driven traction units (71,74) engaging the drill hole wall or by a linear electric motor element (82) co-operating with a drill hole casing (24), which can be moved thereby relative to the drill string. The drill bit (106) of the drill unit is driven rotatably by an electric motor (111,112) or reciprocably by a linear electric motor (125). The drill unit can be of two relatively slidable parts, with fluid pressure, which may be generated within the unit (189) axially loading the drill bit. Drilling forms can be resisted by clamps (129) clamping the unit and/or the drill string to the drill hole wall. The drilling direction can be adjusted by use of these clamps.

Abstract: A device for transmitting torque from a power unit to a drill string or other rotary pipe, and which is constructed upon reverse rotation to preferentially break a threaded connection between the device and a stand of the pipe without disconnecting a plurality of lengths of pipe in the stand from one another. The torque transmitting device includes a tubular structure having a thread adapted to be advanced into engagement with a thread at an end of the pipe, and a shoulder ring carried by and rotatable with the tubular structure and having a shoulder engageable against a shoulder of the pipe to limit advancement of the threads together, with axial forces being transmitted from the tubular structure to the ring by interengageable bearing surfaces which permit limited rotary movement of the structure and its thread relative to the shoulder ring.

Abstract: An adjustable bent housing for controlled directional drilling of well holes. The bend angle of the housing can be conveniently adjusted upon release of the locking nut which is threadably mounted to the motor casing. The locking nut engages an adjusting ring having splines to lockingly engage both the motor casing and the adjustment sub. The adjustment sub and motor casing are lockingly engaged against axial displacement by threads and a plurality of locking balls. An end portion of the outer surface of the motor casing and an end portion of the inner surface of the sub have an angle offset from the central axis to allow angle adjustment. The adjusting ring and locking nut are mounted to the coaxial portions of the components to simplify machining and ensure a clean locking engagement. Adjustment of the bend angle is accomplished by loosening the locking nut to disengage the adjusting ring and allow rotation of the motor casing relative to the universal housing sub.

Abstract: In the preferred application, an acceleration compensation mass is supported in a downhole drilling related housing for independent movement along an axis in response to acceleration of the housing. A control member that moves relative to the housing in a direction parallel the axis to carry out the function of the housed apparatus is connected to a piston in a cooperating bore in the housing to displace fluid when the member moves. A second piston and cooperating bore in the housing is arranged to displace fluid when the mass moves. Fluid plumbing is arranged to connect the two hydraulic cylinders such that the mass and the member, if they move, must move in unison in opposite directions. When the housing is accelerated in the direction along the axis, both member and mass tend to move in the opposite direction relative to the housing but each piston opposes the other and no movement occurs if the pistons have effective areas proportional to the weights of the related member and mass.

Abstract: A check valve sub assembly for series connection in a dual pipe string that extends downhole in a borehole for permitting flow of fluid in one direction through the annular passageway of the dual pipe string and preventing flow of fluid in the other direction. The check valve sub assembly includes an inner tube and an outer annular member for connection into series relationship respective to the inner and outer dual pipe so that fluid flow through the inner pipe is conducted through said inner tube and is maintained separate from the annulus.

Abstract: For making drill holes, in particular under cramped conditions, an apparatus is used which comprises a drill rod consisting of individual segments and guided in the cradle or slide. The individual segments comprise end pieces which are constructed as centering bushes and guide bushes and are to be pushed into each other in such a manner that the necessary torques and pressure forces can be effectively transmitted from the drilling motor. The drilling motor itself is displaceable between two clamping tongs which fix the drill rod or the individual segments and ensure that the latter form in each case a rigid unit to which the pressure and rotary forces can thus be effectively transmitted. The flushing hose extending in the individual segments is connected via a rotary duct to the guide segment of the drill rod so that said hose itself does not participate in the rotation and can therefore be led with the loosely engaging segments round a curve.

Abstract: Atomized water is produced by an atomizer mounted on a drilling device and introduced through a mist flow passage formed in a hollow drill. By applying the atomized water flowing from the atomizer to a cutting bit at the leading end of the drill through the mist flow passage, the cutting bit heated and reaching a high temperature in drilling is cooled. Thus, a rigid material of concrete or the like can be efficiently drilled without being stained with wetting.

Abstract: A member M provides a preferred combination of reduced weight with increased resistance to buckling under compressive loading and includes a tubular member 10 with tool joints TJ at each end for connection to form a drill stem. The tubular member 10 further includes a first portion or pipe section 15 adjacent either one of the tool TJ and may include a second portion or pipe section 15' adjacent the other tool joint TJ which are of smaller or reduced diameter than the adjacent tool joint. An enlarged portion 20 extends longitudinally of the tubular member from adjacent the first portion to adjacent the second portion where there is a second portion adjacent the other tool joint. If there is only one first portion adjacent one tool joint, the enlarged diameter extends from adjacent such first portion to the tool joint at the other end of the tubular member. The enlarged portion 20 has a larger inner and outer diameter than the adjacent first portion.

Abstract: A method and apparatus for creating an underground bore hole using high pressure fluid within a drill string to disturb and displace the subsoil. The drill string is steerable by increasing the pressure of the fluid above a predetermined range to a second range and apparatus is responsive thereto to effect a bending movement and change in the direction of the drill string.

Abstract: A quick detach bit apparatus includes a wear sleeve having a chuck threaded thereinto. A bit is mounted within the chuck. The bit and chuck are interconnected by mating, axially extending splines and grooves. The chuck includes a resiliently mounted segment urged into engagement with the bit. A quick release tool is accommodated in a passage between the bit and chuck. The tool is inserted into the passage and has a thickness sufficient to urge the segment out of engagement with the bit so that the bit is removed from the chuck.

Abstract: A reverse circulation drill rod of the dual tube type having a pin and box at opposite ends with a floating inner tube concentrically situated, the inner tube permitted longitudinal freedom of movement. A plurality of inwardly protruding radial directed lands adapted to encompass and align the inner tube are contained within each box and pin. Compression springs attached to the inner tube residing interiorly to the outer tube provide the longitudinal freedom of movement within limits. As the sections of drill rod are assembled vertically during operation, freedom of lengthwise movement by the inner tube allows stacking of the inner tubes in order that a seal be achieved between the square ends of each inner tube section. Compressed air or liquid is forced down the cylindrical space annulus formed between the outer tube and the inner tube, and drill bit grindings or rock fragments, together with the fluid, is brought to the ground surface in the conduit provided by the inner tube for simultaneous analysis.

Abstract: Manhole cutter for cutting a circular groove of a fixed depth about a manhole, such as in a street, and removing the manhole from the street. The manhole cutter is suspended from a front-end loader or truck-mounted boom and rotated hydraulically from a power take-off unit on the vehicle. A cutter ring assembly with staggered cutters, and inside and outside clean-out slots rotate about a central shaft of the cutter. A manhole plate centers the manhole cutter within the manhole from the cutting operations. When the cut is of sufficient depth to extricate the manhole, a keyway disk is rotated to allow a plurality of lever grip assemblies to grip the manhole. Then, the manhole cutter and the manhole is extricated from the street, leaving a larger sized hole about the area of the manhole which is minimum in size with respect to the manhole.

Abstract: An inner pipe member for a dual-wall drill pipe assembly having an inner pipe member and an outer pipe member, the outer pipe member having a main bore extending axially therethrough including a first bore and a concentric second bore of smaller diameter than the first bore and axially spaced therefrom by a shoulder, and a circumferential recess in the second bore, the inner pipe member comprising a tubular body portion adapted to be telescopically and concentrically received in the main bore and define an annular fluid passage therewith, a first spacer at one end of the body portion for concentrically spacing the one end of the body portion from the other end of the outer pipe member, and a second spacer at the other end of the body portion, the second spacer including first and second surfaces adapted to be received in sliding fit relation within the first and second bore, respectively, for concentrically positioning the other end of the inner pipe member within the outer pipe member, and a projection exten

Abstract: An interchangeable, sectional mining drill and bolt driver system for use with a drilling machine, includes a chuck, a driver, a bolt wrench-drill steel driver, a combination driver, a male hex coupler, a female hex coupler, a universal bar, a flat spring-double dimple clip, and a drill bit. The system can be converted from a vacuum debris removal system to a water debris flushing system by connecting a main water valve to a water system base and inserting a first water valve, a second water valve, and a finishing water insert into respective sections of the mining drill system.

Abstract: A vibration dampening assembly, such as a dynamic balancing apparatus, is connected to a drill bit, a downhole motor or drillstring to exert a variable force to counteract vibration inducing forces. The dynamic balancing apparatus includes a support body which supports a plurality of freely movable masses so that the masses move to a position for opposing an imbalance force which rotates with, and at the same speed as, the drill bit, downhole motor or drillstring.

Abstract: A directional drill bit utilizing pressurized fluid as a means for eroding earth in a forward path of the bit and being used to drill at least a portion of an arcuate path, comprises an elongate hollow body having two sections joined one to the other by a flexible joint, a box end connection, a jet nozzle, an articulation device comprising a spring and a stop, the articulation device being responsive to changes in fluid pressure by permitting a forward portion of the bit bearing the nozzle structure to change angular position with respect to an aft portion of the bit, by the forward portion moving from a first position relative to the aft portion to a second position relative to the aft portion.

Abstract: A drill bit direct drive for deep well drilling tools includes a tubular casing, a rotary machine provided inside the casing and driven by oil well fluid flowing through it, a radially mounted shaft connected to a rotary drill bit and at least one friction bearing exposed to the oil well fluid for axial bearing of the shaft and having at least one trace ring supported on the shaft plus at least one bearing ring supported on the housing and working together with one trace ring. This bearing ring has a number of bearing segments distributed regularly around its periphery including a bearing body supported with respect to the bearing ring so it can be shifted axially and tilted to a limited extent against the action of a spring force.

Abstract: A device for drilling deep holes in the ground has at least two axial drill bits and an equal number of plates each having three shafts axially interconnecting the plates. Two of the shafts are rigidly attached to both plates and the third shaft is pivotably attached to both plates. The two rigid shafts are separable from the upper plate by pulling a locking pin separating a telescopic head of each shaft from the plate. At the separation, the shafts are telescopically shortened by springs and the drilling liquid is automatically shut off to the worn-out drill bit and opened to the new drill bit. The remaining third shaft eccentrically interconnects the plates, whereby the lower worn-out drill bit, at rotation, wears a semicircular evacuation pocket in the wall of the hole. The third shaft is successively pivoted outwards until it forms an angle of e.g. 80.degree. with the axis of the hole. An axle pin having rectangular cross-section retains the upper end of the third shaft via a sleeve with a slit.

Abstract: To stabilize a drill string and to reduce or prevent wellbore deviation in directional drilling, weight rods by which weight is to be applied to drill bit are maintained free-standing and under compression within a drill string while the drill string itself is maintained in tension to limit or prevent lateral deviation of the weight rods in compression. Weight provided by the weight rods is transferred to the drill bit through a load transfer member in compression connected between the drill string and the drill bit.

Abstract: A non-rotating drill string is formed from a plurality of independent, cylindrical sections pivotally connected together by a latch mechanism. The adjacent ends are partially beveled such that the sections can bend in a single direction. Means are disclosed for varying the effect of the beveled surfaces, thus controlling the angle of bend for a given one of the sections. A downhole mud motor (PDM) drives the drill bit through the use of a flexible drive shaft running through the center of a metal-lined, neoprene drilling fluid hose which runs through the interior of the independent cylindrical sections. The total curvature of the borehole drilled by the system equals the sum of the angles of bend between the individual sections.