Abstract: A device for submarine foundation drilling includes: a drilling unit including a head and body interconnected by at least one cylinder, the body being equipped with at least one cutter, the drilling unit being equipped with at least one excavating pump, and hydraulic motors to operate the cutter and the pump; a rigid tubular assembly (2) containing at least one discharge pipe, and pipes for feeding hydraulic fluid to the cylinder and the motors; connecting means (12) between the head of the drilling unit and the lower part of the tubular construction; support means (13) able to be placed at the ocean bottom in front of the head of the drilling unit, means for clamping the tubular assembly; means for suspending the device from a ship, means (5) being provided to furnish hydraulic power, and connecting pipes being provided between the means of furnishing fluid and the upper end of the tubular assembly.

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: Directional drilling is carried out with a rotary drilling tool having a drill string, a drill bit, a drill motor for rotating the drill bit independently of the drill string, an extension sub having both axially contracted and axially extended positions for providing weight to the drill bit when moving from a contracted to an extended position so as to effect a drilling stroke by the drill bit into the wellbore bottom when drilling with the drill bit independently of rotation of the drill string, and a measuring-while-drilling unit acting in conjunction with spiral-bladed stabilizers for effecting proper orientation of the drill bit prior to each drilling stroke.

Abstract: A shaft boring machine including a rotatable cutterwheel assembly with a horizontal axis mounted on a carriage having vertical travel. The carriage is mounted on a slewing base frame and rotates about the vertical axis of the machine. An excavating unit for muck removal is mounted opposite the cutterwheel on the slewing base frame and loads directly from the shaft bottom into a muck hopper. When the hopper is full, it is discharged into a hoist bucket which is hoisted to the surface. The machine is positioned in the shaft by upper and lower gripper systems. Walking cylinders between the two gripper rings advance the machine up or down the shaft.

Abstract: A steering system is disclosed for percussion boring tools for boring in the earth at an angle or in a generally horizontal direction. The steering mechanism comprises a slanted-face nose member attached to the anvil of the tool to produce a turning force on the tool and movable tail fins incorporated into the trailing end of the tool which are adapted to be selectively positioned relative to the body of the tool to negate the turning force. The fins are constructed to assume a neutral position relative to the housing of the tool when the tool is allowed to turn and to assume a spin inducing position relative to the housing of the tool to cause it to rotate when the tool is to move in a straight direction. Turning force may also be imparted to the tool by an eccentric hammer which delivers an off-axis impact to the tool anvil. For straight boring, the tail fins are fixed to induce spin of the tool about its longitudinal axis to compensate for the turning effect of the slanted nose member or eccentric hammer.

Abstract: A method and apparatus for drilling a vertical hole from an underground chamber to the surface includes the emplacement of a preassembled, vertical drill string including a drill bit mounted in a cylinder installed below the underground chamber. When vertical drilling is required, piston lifts the drill string and extends it from the cylinder into the overlying rock. Circulating fluid drives the drill bit and removes the rock debris from the resulting, vertically progressing hole. Drilling continues until the surface is penetrated, and the drill string is retracted into the cylinder, enabling access to the surface through the resulting hole.

Abstract: Disclosed is an apparatus for installing casing and pipe in a lateral well or bore.

Abstract: Automatic Hydraulic Thruster for hole boring including a mandrel and sleeve forming two expandable chambers with plural wall anchor means annularly disposed about the sleeve responsive to pressure differential between one chamber and the bore hole pressure and three-way valve means for automatically connecting the chambers respectively first with mandrel pressure and bore hole pressure and then vice versa.

Abstract: A drilling device which can be lowered in a drill hole consists of a drive device, a drill which is rotated by this drive device and a clamping device formed as a unit which can be engaged with the inside wall of the drill hole and serves to transfer the torque of the drive to the drill. The drill consists of a ring-shaped housing, the outside diameter of which corresponds with the diameter of the drill hole and the upper part of is closed off by a plate. The housing contains several cutting tools which are equipped with bore crowns which serve to cut out a drill core and which are arranged at uniform distances and parallel with the longitudinal axis of the drilling device. Using additional drive devices, the cutting tools are designed to impart impact impulses and/or additional rotational movements in an axial direction. All drive devices are fluid actuated in such a manner that the clamping device is actuated initially and the drill is subsequently activated by the increasing pressure of the fluid medium.

Abstract: A cable following apparatus especially suitable for replacing existing underground cable is disclosed herein. This apparatus includes a tubular main body disposed around and movable along a particular cable in a forward direction while an arrangement of water jets are used to cut through the soil surrounding the cable in front of the forwardly moving main body. At the same time, a high pressure stream of air or similar gas is directed into a circumferential area between the front end of the main body and the cable in a way which is intended to prevent particulate material from passing therebetween and damaging or otherwise disrupting operation of the apparatus.

Abstract: A machine for boring a shaft in earth strata or the like. An annular support ring means having an outside diameter approximately equal to the diameter of the shaft which is selectively engageable or disengageable with the shaft wall by the use of clamping means is disclosed. A carriage means which is slidably mounted on the annular support ring means and orbital thereabout is also disclosed. A rotary cutting wheel means having a diameter substantially smaller than the diameter of the shaft is mounted on the carriage means and is axially displaceable with respect thereto for movement in a direction which may be parallel or inclined with respect to the axis of the shaft. Various drive means for moving the carriage means circumferentially about the annular support ring means, and for moving the rotary cutting wheel means in an axial direction with respect to the carriage means, and for rotating the rotary cutting wheel means are described.

Abstract: An apparatus for producing an upwardly directed drill hole with feed cylinders and a clamping cylinders contains a pressure medium system with a pump, a supply duct and a control valve. In order to attain a particularly favorable and simple design, a second pump is provided, for feeding a second supply duct, from which at least one branch duct containing a choke or the like leads to the drilling head or its tools. The control valve is provided between the first pump and the first supply duct for one set of sides of the clamping and feed cylinders.

Abstract: A down-hole drilling apparatus having a drill tool assembly with a cutting head at one end connected to an umbilical which extends to a retrieval reel on the surface. The umbilical provides electrical power, drilling fluid and means for instrumentation and control signals to be transmitted between the drill tool assembly and a processing device on the surface. The drill tool assembly can propel itself into or out of a bore hole by the cyclical actuation of anchor and ram units or change the direction of drilling by actuation of thruster assemblies in response to control signals sent manually by an operator or automatically by the processing device.

Abstract: The present invention provides an electrically powered system for advancing a rotary boring tool in situations where the inclination of the bore hole is such that the force of gravity does not provide sufficient forward thrust. One or more marine screw propellers are rotated by the motor which itself is restrained from rotation by being fixedly connected to a flexible, twist resistant conduit for conducting the drilling fluid and electric power from the surface. The system may also provide for different rotative speeds for propeller and bit and for counter-rotating propellers to minimize torque forces on the conduit.

Abstract: An hydraulic drive apparatus for use in downhole tools is described. The apparatus provides rotational and translational movement to a cutting tool element disposed in a downhole tool or sonde automatically adjusting advancing motion of the cutting tool to the rate of rotational movement or cutting. The apparatus is controllable from the surface through a wireline and is capable of operating in various modes to facilitate unjamming.

Abstract: This specification discloses a rotary drilling technique for drilling a highy deviated wellbore into the earth's crust wherein a drill string comprised of drill collars and drill pipe is used to advance a drill bit attached to the drill pipe at the lower end of the drill string into the earth and form the wellbore. A first portion of the wellbore is formed to extend into the earth's crust and thereafter a highly deviated second portion of the wellbore is formed by drilling with the drill string arranged to have the drill collars located in the first portion of the wellbore and to apply compressive force on the drill pipe that extends therebelow and thus on the drill bit attached to the lower end thereof to apply the desired weight-on-bit for effective drilling of the second portion of the wellbore.

Abstract: The present invention provides a nonstalling system for advancing a boring tool in situations where the inclination of the bore hole with respect to the vertical is such that the force of gravity does not provide effective forward thrust. A hydraulically powered marine screw propeller adjacent the boring tool provides the necessary thrust for the drilling operation. Pressurized drilling fluid provides the required hydraulic energy. The characteristics of the marine screw propeller are such that it provides maximum thrust at maximum rotative speed but should the tool stall the forward thrust drops to zero preventing stalling.

Abstract: A cable following apparatus especially suitable for use in replacing existing underground cable by reaming around and along the length of the cable is disclosed herein. This apparatus includes a main body or cable follower which is interconnected with the cable to be replaced for slidable movement along the latter. In order to accomplish this, the apparatus includes a specifically designed mechanism for releasably gripping the cable at least at one end preferably two points along the cable in a specifically controlled fashion. At the same time, the apparatus provide means for reaming around the cable, preferably by means of one or more floor jets. Once the soil surrounding the cable has been loosened using this apparatus, the cable can be easily pulled out of the ground. A replacement cable can be attached to the existing cable and therefore pulled into place.

Abstract: Producing a vertical or inclined drill hole by full profile drilling taking place upwardly from a starting location and utilizing a rotatable and displaceable drilling tool and a train of drilling rods which lead to the drilling tool, wherein the drilling tool is, together with the train of drilling rods, subjected, in the vicinity of the upper end of the train of drilling rods, to a force applied in the feed direction, at least part of the reaction of this force being transmitted to a counterabutment which can be releasably secured in the drill hole, and the driving torque for the drilling tool being produced at the starting location and mechanically led from there to the drilling tool.

Abstract: The technique for replacing an existing underground cable and a specific apparatus for doing so are disclosed herein. The apparatus includes a main body or cable follower which is interconnected with the cable to be replaced for slidable movement along the latter. At the same time, the apparatus provides means for reaming around the cable, preferrably by means of one or more fluid jets. Once the soil surrounding the cable has been loosened using this apparatus, the cable can be easily pulled out of the ground. At the same time, the replacement cable can be attached to the existing cable and pulled into its place.

Abstract: The reciprocably supported member is accompanied by means whereby its stroke can be relocated so that it can be used to drive its support if desired, even while it is simultaneously driving a tool or the like connected therewith. Also, the member may have its own onboard drive means; as well as onboard means for removing any debris that the tool generates. The drive means may comprise a combustion engine and the debris removal means may use the combustion gases of the engine as a flush medium for the same. Ordinarily, the flush medium is discharged adjacent the outer periphery of the working face of the tool and removes the debris through apertures adjacent the outer peripheral edge of the same. Other features are also described.

Abstract: This invention is directed to a method and apparatus for drilling horizontal holes in geological strata from a vertical position. The geological structures intended to be penetrated in this fashion are coal seams, as for in situ gasification or methane drainage, or in oil-bearing strata for increasing the flow rate from a pre-existing well. Other possible uses for this device might be for use in the leaching of uranium ore from underground deposits or for introducing horizontal channels for water and steam injections.

Abstract: A self-propelled drilling head comprises a base section including gripper shoes mounted for extension and retraction to selectively grip the wall of a hole being drilled. A first actuator is provided for extending and retracting the gripper shoes. A drilling section is mounted on the base for reciprocation relative thereto. A second actuator is provided for urging the drilling section downwardly relative to the base section when the gripper shoes are extended. A cutter bit is mounted at a lower end of the drilling section. A third actuator is provided for rotating the cutter bit and comprises a first hydraulic motor having a first output shaft. A second hydraulic motor is spaced below and laterally offset from the first hydraulic motor and has a second output shaft extending parallel to the first output shaft. A driven gear is mounted at the end of each output shaft. A drive transmitting gear mechanism is meshingly engaged on opposite sides by the driven gears.

Abstract: There is disclosed a hard rock trench cutting machine comprising a main body assembly and a cutting wheel assembly. A cylinder is transversely mounted on the main body assembly and carries a pair of pistons which extend axially from each end of the cylinder. Pads are provided on each piston to bear against the sidewalls of a trench. Each piston has an end face within the cylinder which, together with an inner sidewall of the cylinder, comprises a pressure chamber adapted to force the pads against the trench. The main body and its cylinder are free to move laterally relative to the pistons when the cylinder is pressurized. Extensible arms are provided between the pistons and the main body assembly for forcing the main body assembly and its cutting wheel forwardly to progressively cut a trench. A steering assembly is provided to shift the main body assembly laterally relative to the pistons and about the central axis of the cutting wheel.

Abstract: An improved deflecting device is provided for a drilling apparatus having a rotatable drill shaft extending from a power source through said deflection device to a drill bit. The deflection device includes an outer housing affixed to the power source and extending axially therefrom. An inner ring is disposed within the housing and encompasses a portion of the drill shaft. An intermediate ring is disposed between the outer housing and the inner ring and has an inner configuration such that the inner ring is immovable relative to the intermediate ring in a first direction, and is prevented from rotating relative to said intermediate ring about an axis parallel to a second direction perpendicular to said first direction, and such that said inner ring is movable relative to the intermediate ring in said second direction.

Abstract: An apparatus for the sinking of a shaft in which a machine platform can be anchored against the wall of the incipient shaft and carries an orbiting tool for cutting away the floor of the shaft, thereby dumping the detritus into a pilot-bore hole continuously drilled by a pilot-bore unit. The latter has a head for advancing the pilot bore and is provided with a worm conveyor running centrally through the shaft to transfer the detritus to a bucket on a loading platform disposed above the main platforms and connected thereto for feed cylinders. The platforms have cylinder arrangements whereby they can be independently anchored to the vertical wall of the shaft.

Abstract: There is provided a method and apparatus for upwardly excavating a shaft through destructible underground rock. The cutting operation is carried out by full face boring without relying on blasting. An operation for supporting the shaft side wall is carried out by means of frame segments loosely following the advance of the bit. The cutting operation and supporting operation are independent from one another. The diameter of the bit is contracted after the cutting operation to allow the bit to be lowered down through the frame segments.

Abstract: A machine for making underground excavations by compacting soil comprises an eccentric shaft having journals on which there are mounted for a free rotation in a sequence, beginning from the front end, a conical member and tapered rolls forming in combination a conically expanding body. The eccentric shaft is coupled to a drive for rotation. The conical member has a through longitudinal diffuser passage, and the eccentric shaft also has a through longitudinal diffuser passage of a cross-sectional area enlarging in the direction away from the face of the excavation being made. The cross-sectional area of the passage of the conical member is smaller than the smallest cross-sectional area of the passage of the eccentric shaft by an amount such that the inside cross-sectional area of the passage of the conical member is substantially within the limits of the inside cross-sectional area of the passage of the eccentric shaft.

Abstract: A downhole weight control device is described for connecting to the upper end of a downhole, pneumatically-operated, impact rock drilling tool for applying a downward force on the tool sufficient to maintain the drill bit in the closed working position. The weight control device has a piston member that has an effective area related to the surface area of the hammer piston in the drilling tool to effectively counterbalance an upward force of the tool tending to lift the tool. The control device also prevents exerting excessive weight on the drill bit. The control device has means for automatically decreasing the working pressure should the drill string be fed for a period of time at a rate greater than the penetration rate of the tool.

Abstract: Method for sinking a cased borehole for producing cased pile foundations. The method uses an apparatus comprising a crane, a drilling appliance capable of being lowered into the borehole and a tube extraction machine with double-acting lifting cylinders for increasing the drilling pressure and for extracting the drop tube after the pile has been concreted. The drilling appliance is capable of producing a borehole with a larger diameter than that of the drop tube and can be fixed to the drop tube by means of a clamping device for withstanding the torque of the motor used for driving the drilling tool. In the method, the drop tube is axially secured and is prevented from locating with respect to the ground, a section of borehole having a greater diameter than the diameter of the drop tube is drilled, and subsequently the axial securement of the drop tube is released so that the drop tube slides downwards by a length corresponding to the length of the section of borehole drilled.

Abstract: A well perforating tool (9) for drilling holes in a well casing substantially from and at right angles to a vertical well bore within which the casing is disposed. The tool (9) includes an elongate housing (15) for insertion within the casing and having a detachable boot (13) at one end thereof for centralizing the longitudinal axis of the tool within the casing. Two motors (53,85) are disposed within the housing (15) for rotating a flexible drill shaft (97), and advancing and retracting the flexible drill shaft (97) with respect to the interior wall of the casing. The entire tool is supported by a cable (19) which also includes power supply and signal lines for independently activating the motors (53,85) from an above-ground control station and ascertaining the depth of drill shaft penetration.

Abstract: In an underground mine, a machine for drilling upwardly is placed in one tunnel of the mine and is used to drill a vertical shaft communicating with another tunnel at a higher elevation. The machine is operated so as to install a liner or casing in the shaft in a step-by-step fashion, substantially concurrently with the corresponding steps of the drilling operation.

Abstract: A process for excavating and constructing a tunnel, and an excavating device are disclosed. This process is directed to excavating and constructing a tunnel under a railway or a road on a banking or on level land in the direction transverse to the railway or road. In this process, pits are dug on the opposite sides of the railway, and then an excavator digs into the wall of a pit on one side so as to go out of the wall of the other pit through the ground left therebetween. In this respect, a hollow casing unit of a box shape is coupled to the rear end of the excavator equipped with a screw conveyor. As the excavator advances or digs forwards a given distance, another casing unit is in turn coupled to the rear end of the preceding casing unit, and then such a step is repeated, until the excavator goes out of the wall of another pit. In this manner, the excavator further digs into the wall of one pit in the position adjacent to the preceding run of casing units.

Abstract: A duct section or other load to be moved axially along a bore hole has two reciprocating drivers mounted on it and two sets of gripping elements. Each driver reacts axially between the load and a set of gripping elements to move the gripping elements relative to the load through a defined stroke in each axial direction. An endless cable with axially extending straight stretches has one stretch connected to each driver to constrain the drivers always to move in opposite axial directions and to begin and end their strokes simultaneously. The gripping elements are so formed that when engaged with the surface of a bore hole, increasing axial force on the load in one direction increases the radially outward force under which they bite into the surface.

Abstract: A bore hole to be deepened far into air-impermeable bedrock has an air-tight lining and an air lock in its upper portion, and it is pressurized below the air lock. A duct comprising endwise connected but disconnectable duct sections extends through the bore hole, its top end open to the atmosphere. A drilling mechanism having a telescoping connection with the bottom of the duct comprises a bit driven by a pneumatic motor that has an exhaust air outlet opening into the duct and a pressure air inlet in the bore hole outside the duct. At intervals along the duct remotely controllable supporting and moving devices are fixed to duct sections, each device having a pneumatic actuator with an inlet opening to the bore hole and an outlet opening to the duct. The devices have gripping elements that frictionally engage the bore hole surface to confine the duct against motion or to move it up or down for raising or lowering the drilling mechanism.

Abstract: A flame jet tool for drilling a hole in the ground at great depths is disclosed. The tool comprises a flame jet lance having a drill bit and an associated fuel system. The lance is disposed in a guide sheath such that the lance may be raised and lowered therefrom. The tool may also include means for capturing debris. In operating the flame jet tool of the present invention, the guide sheath is lowered into a preexisting well hole a specific distance. The guide sheath is fixed to the sides of the hole and the flame jet lance is lowered from the guide sheath. At a predetermined point, the drill bit is ignited and caused to rotate thus increasing the depth of the hole. By the use of the flame jet tool of the present invention, holes of significant depth can be increased and materials of extraordinary hardness can be pierced.

Abstract: A method and apparatus for applying lateral thrust for moving a member, especially for applying lateral thrust to an earth penetrating device. A tubular mandrel of fixed length has four generally toroidal force cells disposed thereon, two laterally expandable force cells having a substantially constant radial dimension, the sum of the lateral dimensions of the lateral force cells always being the same, and two radially expandable force cells having a substantially constant lateral dimension. By alternately expanding and contracting the cells the mandrel is moved laterally. The radial cells engage the walls of a borehole during earth penetration to anchor themselves thereto when expanded. Any type of earth penetrating device may be placed in front of the lateral thrust applying unit, such as a drill bit or a compacting device.

Abstract: A self-driving and self-locking device for traversing the inner walls of channels enclosed on all sides, or for traversing the outer casing of structures with a substantially constant cross-section over their lengths, and for affixing itself thereon, which includes a frame, propulsive elements disposed on said frame and at least one drive means for said propulsive elements to produce movement in the desired direction of movement of said device, said propulsive elements being distributed about the outer or inner circumference relative to a longitudinal axis coinciding substantially with the direction of forward movement and adjustable with respect to the longitudinal axis in a substantially radial direction relative to said frame to adapt to the contact surfaces in the channel or on the elongated structure.

Abstract: A deep well drill is disclosed which utilizes as a prime mover a multistage hydraulic turbine. The system is self-propelled by means of a cylindrical clam shell assembly. The shell sections are spread apart and locked against the surrounding wall of the drilled hole by means of hydraulic cylinders. A hydraulic motor drives the turbine and drill assembly by means of a threaded shaft downward until fully extended. The clam shell is then retracted, and by reversing the hydraulic motor, follows the turbine drill downward until the start position is reached and the cycle is repeated.

Abstract: The casing of a drill motor axis is provided with a deflection barrel free to turn to position the barrel relative to the motor to apply lateral force to the side of the motor directed along any desired radius. A gravity actuated mercury potentiometer connected to the barrel provides a barrel orientation responsive electric transmitter for remote indication of the barrel orientation in the hole being drilled. A hydraulic stepping motor and meshing teeth are used to position the barrel azimuthally about the motor axis with the use of vertical alignment means.

Abstract: A boring assembly is advanced upwardly by thrust rams acting on a column guided traveling cross frame connected to the power tunneler from below by a non-rotating sectional support column. The support column is anchored to a holding table situated underground above the thrust ram while sections are being added to or removed from it. The boring assembly is driven by either a hydraulic motor housed in the cross frame, via a sectional drill stem housed within the support column, or by a hydraulic motor housed directly within the boring assembly.

Abstract: The casing of a drill motor is provided with a deflection barrel free to turn thereon to position the barrel relative to the motor to apply lateral force to the side of the motor directed along any desired radius. A gravity actuated mercury potentiometer connected to the barrel provides a barrel orientation responsive electric transmitter for remote indication of the barrel orientation in the hole being drilled. An annular piston drives a key longitudinally between a straight keyway carried by the barrel and a helical keyway carried by the motor to position the barrel azimuthally about the motor axis. A manifold connected to the motor provides means for making connection to fluid and electric conduits for operating the motor, the piston, and the transmitter.

Abstract: A normally generally horizontal cylindrical open-ended casing having a cylindrical rotor coaxially mounted therein for rotary and axial movements, the rotor having a rear end forwardly spaced from the rear end of the casing and a boring head on its front end projecting forwardly of the front end of the casing. At least one motor is mounted in the casing for imparting rotation to the rotor. A pair of fins are mounted in the casing for movements radially through openings in the casing to engage earth material to control rotation of the casing on its axis in the ground. Fluid pressure rams operate to impart limited axial movements to the rotor and boring head relative to the casing and radially extending and retracting movements to the fins. Controls for the rams and motor provide for common operating pressures to the rams and motor.

Abstract: An apparatus of the type used in forming boreholes in earth formations, as particularly utilized in and about mining operations, which includes the addition of thrust force accumulator structure which enables a continuous drilling progression during the cyclical actuation of alternating borehole anchor mechanism. The device utilizes a conventional form of drill motor and drill bit coupled with a particular form of piston/cylinder anchor mechanism which functions in coaction with a force accumulator compression spring.

Abstract: A cutter wheel is mounted at the lower end of the machine for rotation about a horizontal tubular support. Cuttings are picked up by buckets on the cutter wheel and are directed into the tubular support to be received by an endless bucket conveyor which carries them upwardly to a discharge station. As the machine is advanced the cutter wheel is rotated to make a first cut in the shape of the leading portion of the cutter wheel. The cutter wheel is then retracted out from the cut and is rotated about the axis of the hole. This repositions the cutter wheel so that when it is advanced again it will make a second cut which crosses the first. This procedure is repeated until the desired cross-sectional configuration (e.g. circular) of the hole is obtained.

Abstract: A tunneling machine is disclosed for boring a side drift extending from a main tunnel. The earth boring machine includes a main beam assembly for longitudinal disposition within said tunnel. A cutterhead support assembly is connected to said main beam. A cutterhead assembly including a cutterhead is mounted on said cutterhead support assembly for rotation generally about the longitudinal axis of said tunneling machine. Power means are coupled to said cutterhead assembly for rotation of the cutterhead. A first vertical gripper assembly is slidably connected to said main beam assembly and engageable with the back and the invert of said tunnel for facilitating the advance and guidance of said main beam, cutterhead support, cutterhead assembly, and cutterhead. Guiding thrust means are provided between said first vertical gripper assembly and said main beam assembly for providing a horizontal guiding force to said main beam assembly.