Abstract: A cutting tool or drill bit (10) has a shank (12) with two ends. A chucking end (14) is on one end of the shank (12) and a cutting end (16) is on the other end of the shank (12). At least one flute (30) is formed on the shank (12) between the chucking (14) and cutting ends (16). The flute (30) includes a web (36) and a debris channel (32). The web (36) includes a first (38) and second (40) surface continuous with a debris channel side wall (34). The first surface (38) is substantially parallel to the shank longitudinal axis (18) and the second surface (40) is on an angle from about 100.degree. to about 120.degree. with respect to the shank longitudinal axis (18). The second surface forms the base of the debris channel or groove (32) with the debris channel side wall (34). The debris channel side wall (34) is on an angle from about 10.degree. to about 20.degree. with respect to the shank longitudinal axis (18).

Abstract: A drilling system employs spaced apart cutting members arranged in a helical pattern to form a helical thread within a rock bore. The thread is efficiently fragmented by a wedge-shaped trailing cutting member. Advantageously, a substantial portion of the rock is removed by the fracturing of the internal thread in the rock bore by the uppermost cutting member, taking advantage of the weakness of rock in tension. The rotational speed of the helical cutting system may be controlled as a function of the axial thrust applied to a pilot bit located in front of the helical cutting system.

Abstract: A planting hole forming apparatus includes a central shaft having a longitudinal axis, a bottom leading end and an upper trailing end, and a discontinuous flighting comprising a plurality of flighting sections spiraling around the central shaft at spaced locations along the shaft adjacent the bottom leading end. Some form of drive mechanism, for example a hand-held drill, is used to rotate the central shaft about its longitudinal axis to thereby form the planting hole. The drive mechanism is chosen to accommodate the size of the central shaft and to supply the necessary torque to rotate the central shaft sufficiently to form the planting hole. The structure of the flighting sections is such that while the planting hole is being formed the soil is simultaneously pulverized with a substantial portion of the pulverized soil being left in the hole.

Abstract: An apparatus and method are provided for enhancing fatigue and stress resistance properties of a subterranean well drill pipe string section by providing a helical groove near the pipe to tool joint weld. Stresses in and around the top portion of the pipe are redistributed to and absorbed by the helical groove region of the drill pipe string section, which has a relatively greater resistance to fatigue caused by bending and other stresses, thereby making the drill pipe string section less prone to fail due to rotational, tensile, and bending stresses.

Abstract: A fluid accelerating and pulsation generating apparatus for minimizing loss in fluid energy through frictional pressure drop for fluid passing through the apparatus is characterized by a body having a generally cylindrical chamber formed by a cylindrical inner wall and opposed transverse end walls. One of the end walls has one or more fluid inlet ports arranged therein and defined by passages which intersect the end wall at an angle with respect to a plane normal to the central longitudinal axis of the chamber and generally tangentially with respect to the cylindrical inner wall. Plural discharge passages intersect the opposite end wall at a curved wall portion formed between the cylindrical inner wall and the opposite end wall. The discharge passages may also be arranged to have their axes extending tangentially with respect to the inner cylindrical wall and at a predetermined angle with respect to a plane normal to the central longitudinal axis of the chamber.

Abstract: A rock drill is formed of an axially extending shank (2) with a drill head (1) at one end and chuck end (3) at the other end. The axially extending outside surface of the shank has at least one helically extending conveying groove (4, 5) and at least one helically extending land (6, 7). The land (6, 7) forms the radially outer surface of the shank (2). Grooves (8, 9) extending perpendicularly of the shank axis are formed in the surface of the land.

Abstract: This invention concerns an accessory, to be inserted in a drill string behind a drill bit, to provide separation of the liquid and air components of a flushing medium. The accessory comprises an inner housing (36) within an outer housing (34). A liquid/gas medium enters through opening (50) onto spiral raceway (48). Holes are provided at intervals along spiral (42). Liquid in the medium is centrifuged by the spiral (42) and projected into the chamber between inner and outer housings (36,34). The expelled liquid (52) falls to the base (70) of the housing (34) where it passes through apertures (38) into the drill bore. Once the medium has traversed the spiral (42) essentially only gas remains to pass through the opening (62) to the drill bit.

Abstract: An axially elongated rock drill has a chucking shank section (1) at one end and a drilling tip (2) at the opposite end, helically arranged first grooves (3, 4) are located in the outside surface of the drill and extend from adjacent the drilling tip towards the chucking shank section. Helically arranged lands (R) are located between the first grooves and form the outside surface of the drill. The lands have helically arranged auxiliary second grooves located between helically arranged guidance regions (7, 8, 9, 10). Accordingly, the second grooves are spaced from the first grooves by the guidance regions. The width (BH) of the first grooves (3, 4) is approximately twice the total width (BG) of the lands, that is, the width of the two guidance regions and one second groove.

Abstract: A drill bit reamer stabilizer has an upper and lower stabilizer on a bottom hole assembly with the lower stabilizer as close as possible to the drill bit. This arrangement reduces deviations when drilling a straight hole. Furthermore there is a reamer portion at the leading edge of the lower stabilizer to ensure the drilled hole is reamed out to the nominal drill bit size regardless of drill bit wear. The assembly has a longitudinal shaft with a shank on a top end for connection to a drilling string, an internally threaded box in a bottom end of the shaft for connection to the drill bit, the internally threaded box having an internally tapered lip to overlap a drill bit shank. The lower stabilizer has spiral flutes and lands adjacent the bottom end of the shaft, the flutes have polycrystalline diamond layer inserts at the leading edge of the stabilizer to provide a reamer, the inserts ream a hole substantially the same size as the nominal size of the drill bit.

Abstract: A drilling tool and, in particular, a rock drill, which is of multi-part design, is proposed. In this, the drill head and/or the clamping shank is connected via a helical shank designed as a threaded rod.

Abstract: A system for simultaneously lining and cleaning an existing sewer pipe, and for laying horizontal pipe without digging a trench, includes a planetary gear assembly mounted on a drilling rig. A liner pipe or outer pipe which is to be laid underground is placed over an inner auger, with the forward end of the liner pipe located behind the auger drill bit. The opposite end of the auger is attached to the sun gear of the planetary gear assembly; and the outer pipe is secured to the ring gear of the assembly. The auger is rotated in one direction, causing the outer pipe to rotate in the other direction; and the pipe and auger are pushed simultaneously through the pipe to be lined or through the soil. Once a section of auger and liner pipe have been pushed in place, the planetary gear assembly is disconnected from the auger and the liner pipe, new sections of auger and liner pipe are connected to the existing sections at one end, and to the planetary gear assembly at the other end.

Abstract: A drilling tool and, in particular, a rock drill for the creation of breaches in concrete or masonry for the use of drill hammers is proposed, which is configured as a cross drill bit having four cutting fins. In order to optimize drilling capacity, the drilling tool is provided with a cross drilling head which merges in one piece into a conveyor spiral matched to the drill head. A purpose-specific cutting element facing serves to optimize the drilling capacity.

Abstract: A boring tube has at least one tubular base body having a throughgoing longitudinal passage and an outer side and a coil arranged on the outer side of the base body and extending over its whole length. The coil has a pitch of 1 m-3 m and a radial width which starting from the outer side of the base body is at least 10 mm.

Abstract: A drill bit for drilling holes in concrete and asphalt, or the like, includes a circular drill bit body having two helical grooves in its cylindrical side surface. Pressurized air is injected into the drilled hole through a passage system extending longitudinally within the drill bit. The injected air is forced out of the drilled hole through the helical grooves, such that particulates formed by the drilling process are flushed with the air out of the hole. The flushing action prevents the bit from becoming immobilized by heated asphalt sticking against the drill bit side surface.

Abstract: A ground fracturing probe to form fractures in subsurface formations includes an elongate, hollow body with a conical penetrating tip at its distal end. A threaded tool joint is at the other end of the body to allow the probe to be coupled to the drill string of a drilling rig. A helical flight is on the exterior surface of the body and extends along a portion of the body length between the tool joint and the penetrating tip. The helical flight varies in diameter over its length to define a cutting zone adjacent the penetrating tip, an injection zone above the cutting zone and a sealing zone above the injection zone. The helical flight increases in diameter in the cutting zone from the tip to the injection zone but decreases abruptly in diameter at the injection zone. The diameter of the flight remains constant in the injection zone and increases in diameter at the interface between the injection zone and the sealing zone.

Abstract: In order to achieve improved flow properties for a flushing medium charged with rock particles freed during the drilling phase, an injection drilling anchor is provided with anchor rods, coupling members, injection valves, an intermediate member containing a non-return valve, as well as drill head, which are designed such that these components are connected one to the other below one another always by screw fittings, so that in the assembled state one has a fully homogeneous structure from the drill head upwards. The drill head has an external thread extending uniformly over the full length and consequently has a uniform diameter, so that after drilling has taken place, starting from the mouth of the borehole, a spacer can be pushed within the borehole along the full length of the borehole over the anchor rods to any desired point.

Abstract: The drilling tool (1) intended to widen a drilling well bears a series of helical arms (3) resting at a first end on a first fixed flange (4) so as to be able to turn on themselves by a portion of a turn under the control of a rotating ring (9) driven by an opening mechanism (10) controlled by a variation in the pressure of the drilling fluid, while the other end of the arm (3) slides along a groove (21) provided in a second flange (5).

Abstract: A drill steel is provided for use in percussive drilling. The drill steel has an elongate body for transmitting energy between a drill rig and a drill bit, and each end of the drill steel has an end coupling portion. The body has a means for reducing vibrations at the end coupling portions comprising a twisted portion between the two ends. The twisted portion transmits less vibration than untwisted drill steel of corresponding size under the same conditions. The twisted portion also promotes bending in the drill steel in at least two or more places. The twisted portion may have a helical pitch of between one half turn over the length of the drill steel and two turns per foot. The twist may be of uniform or variable pitch, or a combination thereof.

Abstract: An apparatus and a method for drilling a tunnel utilize hydraulic means comprising a cylinder and a piston to enable independent adjustment of the driving force acting on the protecting tubes and the driving force acting on the drilling tool/conveying tubes. The hydraulic means acts as a thrust bearing and moves freely in the longitudinal direction of the drilling apparatus in response to forces acting on the drilling tool which are detected as changes in pressure in the hydraulic means.

Abstract: A well clean-out tool includes a cylindrical member in which a helical conveyor screw is arranged for vertical sliding movement relative to the cylindrical member. The tool is lowered into a well bore until the shoe contacts debris within the bore. At that time, the screw is caused to descend relative to the cylindrical member, whereupon a lower end of the screw projects slightly below a lower end of the cylindrical member, and a rotary coupling between the screw and the cylindrical member is released, and a spring is caused to store energy. Thereafter, the screw is rotated relative to the cylindrical member, while the spring presses the cylindrical member against the debris in order to resist rotation of the cylindrical member. The screw projects only slightly downwardly beyond the lower end of the cylindrical member, e.g., less than one inch, in order to convey debris upwardly within the cylindrical member.

Abstract: A well clean-out tool includes a cylindrical member in which a helical conveyor screw is arranged for vertical sliding movement relative to the cylindrical member. The tool is lowered into a well bore until the shoe contacts debris within the bore. At that time, the screw is caused to descend relative to the cylindrical member, whereupon a lower end of the screw projects slightly below a lower end of the cylindrical member, and a rotary coupling between the screw and the cylindrical member is released, and a spring is caused to store energy. Thereafter, the screw is rotated relative to the cylindrical member, while the spring presses the cylindrical member against the debris in order to resist rotation of the cylindrical member. The screw projects only slightly downwardly beyond the lower end of the cylindrical member, e.g., less than one inch, in order to convey debris upwardly within the cylindrical member.

Abstract: A footing auger has a helical auger portion with a chuck on one end for attaching the footing auger to a rotating power tool, a rod-like pilot on the other end of the footing auger for guiding the footing auger in a predetermined direction, and forwardly directed hardened blade extensions attached to the helical auger portion and the pilot that are arranged and configured to chip the dirt or other substances from the desired hole.

Abstract: A tubular drill string element, such as a stabilizer or tool joint, comprises an outer surface having in circumferential direction a ratchetted profile. The ratched profile is preferably oriented such that provides low resistance against right hand rotation but high resistance against left hand rotation of the drill string.

Abstract: A component for attachment to a drillpipe which is part of a drillstring carrying a drillbit, said drillstring rotatably driven in a working direction, which drillpipe contains a standard box tool joint at one end and a standard pin tool joint at the other end, which tool joints are of a diameter greater than the section of drillpipe between the two joints, and which drillpipe component is comprised of two elongated cylindrical half sections for clamping over at least a portion of the narrower section of drillpipe and which component, on its outer surface, contains at least one helical pumping chamber having a twist, when viewed in axial elevation, opposite to that in which said drillstring is rotatably driven in said working direction, said pumping chamber, when view is traverse section, having an undercut portion relative to the surface of the drillpipe component, said undercut portion defining a lip.

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: The device for drilling holes in the ground comprises a body (1), a drive and a base member (3), connected with the body by means of a thread (4) and provided a with a lug (7) located on an external side surface (6). The lug (7) is intended for locking the base member (3) relative to the body (1) and is projected beyond the latter. One of the sides (10) is inclined to the generatrix of the side surface (6) of the base member (3) in the direction creating a turning-in moment at the connecting thread. Located on the base member side surface is an additional lug (12) which creates a turning-in moment at the connecting thread in case the device is reversed.

Abstract: The drill bit for producing a cylindrical drilled hole, especially in concrete, has a shank and a drilling head at one end of the shank provided with at least one helically extending drilling dust groove. At least two bulb-like shank enlargements (6,7) are provided on the shank (5) arranged in succession axially. Each of the shank enlargements (6,7) has the same maximum diameter and the drilling head has a drilling head diameter which is at least as great as the maximum diameter of the shank enlargements (6,7). Advantageously two drilling dust grooves with semicircular cross sections are provided on the shank displaced from each other radially by about 180.degree. to form a cross member with cutting edges on the drilling dust grooves.

Abstract: A flexible drill string for curving a vertical borehole laterally towards the horizontal, comprising an elongated flexible casing made of a plurality of sections with each section having a longitudinal central axis. Each section is attached to an adjacent section such that the casing string can conform to a segment of a curve. An elongated flexible drilling string is rotatably received within the flexible casing and an annulus is formed between the casing and drill string. The drill string has a central fluid passageway of resilient material surrounded by a plurality of longitudinally extending bendable members that jointly encapsulate the central fluid passageway and forms an outer housing about the drill string. The drill string central passageway is an elastomeric conduit and the plurality of bendable members are placed circumferentially thereabout and are connected together to form the housing.

Abstract: The drilling of highly angulated wellbores (with a rotary rig having a drill string terminated with a bit wherein drilling fluid is employed) is improved by employing in the highly angulated drill string a length of drill pipe which has a helical ridge disposed thereabout such that the flight of the helical ridge is wound so as to rise from the bit with the rotation of the drill string and the height of the helical ridge above the length of the surface of the drill pipe is 1 to 15 percent of the diameter of the drill pipe.

Abstract: A method and apparatus is provided for drilling high-angle, directional and horizontal subterranean wells for hydrocarbon extraction. A drillstring component having at least one helical undercut pumping chamber is described, which drillstring component is designed especially for increased flexibility in directional drilling applications. The undercut pumping chamber of the invention drillstring component is designed to improve volumetric efficiency in removing cuttings from the borehole, and to reduce the incidence of differential sticking or key-seating.

Abstract: An intermediate weight member (10) having a variable cross-section or bending moment of inertia as a function of member length is disclosed. At one end of the member (10) a slip and elevator section (14) is provided. A partially grooved section (16) of a diameter greater than that of the slip and elevator section extends between the slip and elevator section (24) and the other end of the member (10). The partially grooved section (16) includes two variable depth grooved sections (18, 20) separated by an ungrooved section (22). The ungrooved section (22) includes hardbanding rings (26, 28). The spiral grooves (30A, 30B, 30C) of variable depth grooved section (18, 20) vary in depth as a function of member length such that the bending moment of inertia varies as a function of length from the slip and elevator section (14) to the lower end of the member (10).

Abstract: An apparatus has an eccentric shaft on which are mounted rolls connected to one another by flexible members in the form of a corrugated collar for end sealing of the rolls and with auxiliary members for radial sealing of the rolls. The auxiliary members are received in a radial clearance defined between the adjacent rolls which are made hollow.

Abstract: A drilling tool which is suitable especially for clearing drill dust from a drillhole in rock-drilling work is provided. For this purpose, the spiral shank has brush elements (6, 17) which are arranged in the groove bottom of a conventional drilling tool or which themselves form spiral feed coils.

Abstract: An improved drill pipe assembly that is formed as a concentric walled pipe having both an axial and an annular space therethrough, and the pipe section includes means for selectively communicating the adjoining annular spaces through the series of respective box end/pin end joints whereby equipment compartmentation, conductor traverse, ballast containment, gas pressurization and weight addition can be effectively utilized in controlled manner. The pipe is assembled by threaded engagement of the pin end joint to each of an outer pipe and an inner pipe, and subsequent threaded joinder of the concentric pipes to a box end joint while also utilizing an intermediate double-threaded sleeve between the inner pipe threads and the box end collar threads.

Abstract: A device for facilitating the retrieval of a drill bit from a crooked hole, a soft rock or a broken rock formation is disclosed. The device is secured to a drill string at one end and to a drill bit an an opposite end. The device includes a cylindrical member having a helical member of gradually increasing radial thickness secured about its periphery. The helical member has a plurality of hardened cutter members secured to and projecting from its periphery. The radial thickness of the helical member is greatest at that section of the device closest to the drill bit and least at that section of the device closest to the drill string. The device clears obstructions in the bore hole above the drill bit to ease the removal of the bit from the hole, while at the same time, the device avoids enlarging the bore hole on either the advancing or retrieving trip of the drill string. The device further serves to maintain alignment of the drill string during advancement into and retrieval from the bore hole.

Abstract: Nozzle-effect well apparatuses including nozzle-effect protectors, centralizers and stabilizers and related methods, the apparatuses having two or more blades or ribs extending outwardly from a body, the blades or ribs spaced apart further at one end of the apparatus than the other; in one embodiment, the wall thickness of the apparatus varying so that one end is thicker than the other or a portion or portions between the ends are thicker or thinner in wall thickness than other portions; in another embodiment, portions of valley areas between ribs or blades varying in size to create nozzle effects.

Abstract: A steerable earth boring device comprises a compaction auger rotatably mounted to a housing at one end of the auger such that the compaction auger is substantially externally exposed. A steering tip is pivotably disposed at the other end of the compaction auger for providing steering control for the earth boring device. An internally housed steering mechanism is provided for pivoting the steering tip relative to the compaction auger while the auger is rotating. The steering mechanism includes a non-rotatable cam disposed within and pivotably connected to the housing and a follower rotatable with and pivotable relative to the compaction auger. The cam and follower contact at a bearing surface so that pivoting motion of the cam is transmitted to the rotatable follower. A control member is connected between the follower and the steering tip, extending through the compaction auger, to transmit pivoting of the follower to pivoting of the steering tip.

Abstract: A drilling tool, in particular for use in axially striking drive machines for drilling in rock, concrete or the like, which drilling tool is designed from both a vibration point of view by varying the abrupt changes in cross-section and from a drilling point of view by optimising the transport of the drilling dust. In order to arrange, from a vibration point of view, the abrupt changes in cross section, caused by the flute webs, in asymmetrically arranged axial positions, the inclination of the conveying flute constantly changes its size within a lead. Furthermore, the radial, tangential and axial force vector which acts on the drilling dust constantly changes its size, the radial force vector also changing its direction. In this way, the drilling dust is subjected to a constantly changing acceleration.

Abstract: A drilling device for producing drill holes with undercuts comprises a drill having a drill shaft with extending drill blades, a shoulder projecting from the drill shaft, and a guiding sleeve surrounding the drill shaft between the shoulder and the drill blades, the guiding sleeve having two ends provided with openings of different sizes, the guiding sleeve having a sleeve edge which forms a support for the shoulder and a wall abutment for the collar.

Abstract: There is described a downhole stabilizer having a number of spiral fin-like blades. Each blade is provided with a pocket each of which carries an omni-directional rolling element bearing in the form of a ball which is engaged against the wall of the drilled hole.

Abstract: An improved drill pipe assembly wherein each pipe section is formed as a concentric walled pipe having both an axial and an annular space therethrough, and the pipe section includes means for communicating the adjoining annular spaces through the series of respective box end/pin end joints whereby equipment compartmentation, conductor traverse, ballast containment, gas pressurization and weight addition can be effectively utilized in controlled manner.

Abstract: A method of rapid earth excavation without damaging buried pipe, cable or other underground objects utilizes drills and augers having soft cutting edges and/or control of the torque and weight of the boring apparatus. In one embodiment, the bit of a drill, or bottom end of an earth auger is equipped with inserts formed of soft polymeric material. Another embodiment of an earth auger apparatus has soft polymeric material on the leading cutting surface of the flight, or the auger flight may be formed of soft polymeric material. The flexibility and low abrasion of the polymeric material prevents damage to the object contacted. Another embodiment has a dual concentric auger with a small earth-auger rotatably mounted inside the shaft of a larger auger and driven independently such that each is capable of providing and maintaining a torque adequate to create a given hole diameter but sufficiently below that which would damage the object expected to be encountered.

Abstract: An auger for use in drilling into the earth under rotative movement in one direction of rotation, the auger having a cylindrical stem and a helical flight extending along the length of the stem, the helical flight being defined by adjacent segments of opposite flight orientation. The auger of the present invention enables the drilling of fast holes of any conventional size to any conventional depth required in overburden and bedrock. It reduces the tendency of bore hole wall collapse through the use of bore hole material to stabilize the hole and reduces the amounts of drilling muds needed.

Abstract: A drilling tool is proposed which is preferably suitable for making apertures in concrete work or masonry is fissured rock. To avoid damaging an interchangeable conveying helix (4), the connection between the conveying helix (4) and drilling head (3) is made as a frictional-resistance connection (FIG. 2).

Abstract: A rock drill for rotary and/or percussive stress, in particular for use in percussion or hammer drilling machines, is proposed, which by its geometrical design makes improved efficiency and simplified production possible. For this purpose, the feed spiral 5 is designed alternately with horizontal feed sections 8,8' with a 0.degree. pitch, and adjoining lead sections 9,9', the respective feed sections assuming an angle of rotation of 90.degree. on the drilling tool.

Abstract: A rotary gad for a ground drill includes an elongated front body having a front end and a rear end with front spiral blades being disposed on the outside of the front body. The front body has an elongated front axial passage, and a front core rod is disposed in the front axial passage. The front body is rotatable about the front core rod. The front core rod has a front end and a rear end. An elongated rear body has a similar construction and a pushing section is provided on a rear axial passage in the rear body. The pushing section has a front side and a rear side. A rear ball element is disposed between the rear side of the pushing section and the front end of a rear core rod, and a front ball element is disposed between the front side of the pushing section and the rear end of the front core rod. Coupling means couple the front and rear bodies to provide for rotation of the front and rear bodies in opposite directions about the front and rear core rods.

Abstract: A sonde has an at least approximately cylindrical drill-stem member, whereby the drill-stem member may be coupled with other drill-stem members into a drill string. A spiral winding is longitudinally about the drill-stem member for conveying drilled out earth up to a surface of the earth when the drill-stem member is rotated into the earth, whereby the drill-stem member is an auger. At least one longitudinal surface portion of the drill-stem member is an electrical insulator that extends inwardly of the surface portion at least part of a radius of the drill-stem member. At least one measuring electrode is embedded in the electrical insulator. A connecting arrangement is in the drill-stem member for connecting the measuring electrode to electric operation and measuring equipment, whereby the auger is also an electrically logging sonde.

Abstract: A rotor (1) of a screw hydraulic downhole motor, made as a hollow multiple-start screw featuring a substantially constant wall thickness. The ratio of the length of the rotor (1) cross-sectional outside contour to the length of the circumscribed circle of the contour is substantially within 0.9 and 1.05. When making the rotor (1) a forming element is inserted into a tubular blank, and a fluid pressure is applied to the outside blank surface. A device for making the rotor comprises a hollow housing accommodating a forming element installed on centering bushings. The bushings have fitting areas adapted for the ends of the tubular blank to fit thereon.

Abstract: A drill string apparatus for the controlled absorption of both axial and torsional forces exhibited on the well string during drilling operations. The device is adapted to be connected in the drill string above the drilling tool in order to control the forces acting on the bit and to arrange the mean weight on bit for the selected drilling operation. Generally, the apparatus includes an outer casing coupled at its upper end to the drill string and an inner assembly telescopically received within the outer casing and connected at its lower end to the lower part of the bottom hole assembly or the drilling tool. Rotational torque is transferred from the drill string and outer casing to the inner assembly and drill bit by a series of helical splines. The mean weight on bit is controlled through an interchangeable pressure control nozzle mounted at the top of the inner assembly.

Abstract: A rotary rock drilling machine comprises a carriage having two ends, a rotary drilling drive arranged longitudinally displaceable on the carriage, a guiding head arranged on one end of the carriage, the guiding head and the rotary drilling drive defining a longitudinal axis of the machine, a drilling rod composed of a plurality of drilling rod parts which are releasably connected with one another, the drilling rod parts having a plurality of screw convolutions, the drilling rod parts having one end having a coupling pin with a snap pin and another end having a coupling bush with an engaging opening for the snap pin, a positioning device in the guiding head arranged to arrest a rotary position of the drilling rod, and an unlocking device for the snap pin, the positioning device including a locking bar which extends substantially parallel to the longitudinal axis and displaceable radially to the drilling rod, and which is insertable in at least one radial slot provided in the screw convolution of the drilling r