Abstract: A method for reforming or rerounding an underground pipe includes the initial steps of inserting a reforming tool into the underground pipe and locating the pipe reforming tool at a location to be reformed. At least two arms of the reforming tool are then extended into engagement with the inner periphery of the underground pipe, which arms push the underground pipe outwardly in a manner effective to change its cross-sectional shape. The arms may then be retracted and the tool withdrawn from the pipeline. Such “reforming” or “rerounding” tool is preferably mounted at the distal end of a rod string so that the tool can be pushed, pulled and/or spun by operation of the rod pulling and pushing machine powering the rod string.

Abstract: A portable winch suitable for use in underground pipe bursting and replacement includes a mounting frame positionable at a top opening of a hole such as a receiving pit or manhole. A telescoping mast having a series of nested, top and bottom mast sections is mounted on the frame. A powered winch unit, also mounted on the frame, includes a drive unit and a cable. A guide assembly includes a sheave that guides the cable from the drive unit to the bottom mast section. Suitable means are connected to the frame for mechanically raising and lowering the mast into and out of the hole. As such, the mast according to the invention does not require assembly or disassembly at the beginning and end of each job. The mechanical means for raising and lowering the mast is preferably the powered winch unit.

Abstract: A cable pulling machine of the invention includes a frame, a mechanical linkage including first and second links having first and second cable gripping shoes disposed thereon respectively in opposed positions, a latching cylinder actuable to cause the mechanical linkage to pivot on multiple axes to bring the shoes into engagement with a cable disposed therebetween, a main cylinder having one end mounted on the frame and actuable to move the linkage in a manner effective to pull the cable in a pulling stroke once the latching cylinder has brought the shoes into engagement with the cable, and suitable means for extending and retracting the main and latching cylinders. The machine may also include suitable means for holding the cable in tension between pulling strokes, such as a pivoting wedge mechanism as described hereafter.

Abstract: An impactor for use with a directional boring machine for replacement of underground pipes includes a bursting head having a rearwardly opening recess and a front end opening that communicates with the recess. An inlet pipe is connected at its front end to a distal end of the drill string and extends into the recess of the bursting head through the front end opening. A striker is mounted for sliding movement along the inlet pipe, and a distributing mechanism responsive to pressure fluid supplied through the drill string and inlet pipe causes the striker to reciprocate in the rearwardly opening recess of the head to deliver forward impacts against the bursting head. The striker and distributing mechanism are mounted in a tubular housing, and a pulling connection is provided by which the impactor can be pulled by the drill string while the striker is delivering impacts against the head in the same direction as a pulling force exerted by the drill string.

Abstract: A cable pulling machine of the invention includes a frame, a mechanical linkage including first and second links having first and second cable gripping shoes disposed thereon respectively in opposed positions, a latching cylinder actuable to cause the mechanical linkage to pivot on multiple axes to bring the shoes into engagement with a cable disposed therebetween, a main cylinder having one end mounted on the frame and actuable to move the linkage in a manner effective to pull the cable in a pulling stroke once the latching cylinder has brought the shoes into engagement with the cable, and a mechanism for extending and retracting the main and latching cylinders. The machine may also include a mechanism for holding the cable in tension between pulling strokes, such as a pivoting wedge mechanism as described hereafter.

Abstract: A method for the removal of a ductile pipe includes passing a strand through the ductile pipe, crimping the ductile pipe in at least one location so that it is secured in a crimp about the strand and pulling the strand from an end of the ductile pipe with a winch or hydraulic puller. Preferably, the strand is a solid wire or wire rope and may be pushed through the pipe with a power wire feeding apparatus. As the strand and ductile pipe are pulled, segments of the pipe and strand are cut at the end of the pipe proximate the winch or puller.

Abstract: A method for installation of an underground pipe includes an initial step of boring a pilot hole through the ground at a predetermined grade angle by extending a drill string having a steerable boring bit mounted thereon through the ground. Upon reaching an end location for the pilot hole, the bit is removed from the drill string, and an expander having a diameter greater than the pilot hole is attached to the drill string, which expander is backed by an impact device such as a pneumatic impactor including a striker that delivers repeated impacts to a rearwardly facing surface of the expander, and by a pipe drawn along behind the expander. The expander is pulled back through the pilot hole at the grade angle while the impactor is operated to aid progress of the expander through the ground and pull the pipe into place behind the expander.

Abstract: A ground piecing tool includes a housing and an air distributing mechanism that reciprocates a striker to impact a chisel shaft in response to a supply of compressed fluid including a fluid inlet tube mounted in the bore of the striker having a radial port, a rear end of the inlet tube being in communication with the distributing mechanism, wherein the housing and chisel shaft cooperate to define a front chamber that decreases in volume as the chisel moves forward relative to the housing, and wherein the chisel shaft has a radial passage therein that conducts compressed fluid from the radial port of the inlet tube to the front chamber, which is configured to form an air spring.

Abstract: An impactor for use with a directional boring machine for replacement of underground pipes includes a bursting head having a rearwardly opening recess and a front end opening that communicates with the recess. An inlet pipe is connected at its front end to a distal end of the drill string and extends into the recess of the bursting head through the front end opening. A striker is mounted for sliding movement along the inlet pipe, and a distributing mechanism responsive to pressure fluid supplied through the drill string and inlet pipe causes the striker to reciprocate in the rearwardly opening recess of the head to deliver forward impacts against the bursting head. The striker and distributing mechanism are mounted in a tubular housing, and a pulling connection is provided by which the impactor can be pulled by the drill string while the striker is delivering impacts against the head in the same direction as a pulling force exerted by the drill string.

Abstract: A portable winch suitable for use in underground pipe bursting and replacement includes a mounting frame positionable at a top opening of a hole such as a receiving pit or manhole. A telescoping mast having a series of nested, top and bottom mast sections is mounted on the frame. A powered winch unit, also mounted on the frame, includes a drive unit and a cable. A guide assembly includes a sheave that guides the cable from the drive unit to the bottom mast section. Suitable means are connected to the frame for mechanically raising and lowering the mast into and out of the hole. As such, the mast according to the invention does not require assembly or disassembly at the beginning and end of each job. The mechanical means for raising and lowering the mast is preferably the powered winch unit.

Abstract: A pneumatic ground piercing tool includes a tail assembly including a tail nut and tail cap, the tail cap having a plurality of discharge ports for exhausting spent compressed air, the discharge ports opening into an annular space between a rearwardly opening recess of the tail cap and an air supply conduit such that the exhaust ports are shielded by a side wall of end cap from plugging when the ground piecing tool is operated in reverse mode.

Abstract: A method of the invention uses a pneumatic ground piercing tool having a reversing mechanism with a supplemental air line capable of supplying compressed air for reverse operation to a radial port in the air distributing mechanism. This radial port is located between a pair of bearing surfaces on the step of the air inlet conduit, and when pressurized by the supplemental air line, causes the front pressure chamber to receive compressed air earlier than normal, shifting the stroke of the striker rearwardly so that the tool operates in reverse. Such a method includes the steps of operating the tool in forward mode by supplying compressed air to the first air hose, and operating the tool in reverse mode by supplying compressed air to the second air hose while permitting partial venting of the front pressure chamber through the first air hose.

Abstract: A pneumatic ground piercing tool includes a tail assembly including a tail nut and tail cap, the tail cap having a plurality of discharge ports for exhausting spent compressed air, the discharge ports opening into an annular space between a rearwardly opening recess of the tail cap and an air supply conduit such that the exhaust ports are shielded by a side wall of end cap from plugging when the ground piecing tool is operated in reverse mode.

Abstract: An impactor for use with a directional boring machine for replacement of underground pipes includes a bursting head having a rearwardly opening recess and a front end opening that communicates with the recess. An inlet pipe is connected at its front end to a distal end of the drill string and extends into the recess of the bursting head through the front end opening. A striker is mounted for sliding movement along the inlet pipe, and a distributing mechanism responsive to pressure fluid supplied through the drill string and inlet pipe causes the striker to reciprocate in the rearwardly opening recess of the head to deliver forward impacts against the bursting head. The striker and distributing mechanism are mounted in a tubular housing, and a pulling connection is provided by which the impactor can be pulled by the drill string while the striker is delivering impacts against the head in the same direction as a pulling force exerted by the drill string.

Abstract: A method of replacing an existing underground pipe, especially a sanitary sewer line, uses a boring machine that advances a drill string of hollow rods through the existing pipe.

Abstract: A drill bit configured for use in horizontal directional boring includes a spoon-shaped body with a rearwardly angled or inclined arcuate front end face that widens from a leading edge to a trailing edge in a circumferential direction, the front face sloping rearwardly from a leading side surface to a trailing edge in a circumferential direction, the leading and trailing side surfaces extending rearwardly in from the front end face. The leading side surface is wider than the trailing side surface. In one configuration, the front end surface and leading side face are each provided with a plurality of carbide inserts or studs which may be arranged in a row.

Abstract: An impactor for use with a directional boring machine for replacement of underground pipes includes a bursting head having a rearwardly opening recess and a front end opening that communicates with the recess. An inlet pipe is connected at its front end to a distal end of the drill string and extends into the recess of the bursting head through the front end opening. A striker is mounted for sliding movement along the inlet pipe, and a distributing mechanism responsive to pressure fluid supplied through the drill string and inlet pipe causes the striker to reciprocate in the rearwardly opening recess of the head to deliver forward impacts against the bursting head. The striker and distributing mechanism are mounted in a tubular housing, and a pulling connection is provided by which the impactor can be pulled by the drill string while the striker is delivering impacts against the head in the same direction as a pulling force exerted by the drill string.

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

Abstract: A method of slitting a flexible conduit in an underground bore, the conduit having entry and exit ends thereof exposed for access, includes: (1) fitting a retainer to flexible underground conduit adjacent to the entry end thereof, the retainer securing the flexible conduit to limit longitudinal movement thereof relative to the bore, (2) passing pulling means through the flexible conduit; (3) connecting the pulling means to a pipe slitter, and (4) pulling the pipe slitter through the retainer and flexible conduit to slit the conduit, the retainer holding the flexible conduit taut as the slitter passes through the conduit. In one embodiment, the retainer is a shoring clamp assembly including a pair of ring clamps that are secured onto a split end of the flexible conduit and transfer the longitudinal forces applied to the conduit during the slitting operation to an adjacent structure such as a pit wall, thereby holding the conduit taut during the slitting operation.

Abstract: The invention provides a rock drilling bit with a plurality of cutting teeth raked into the cut of the drilling bit. Such teeth are oriented at an angle of at least about 30 degrees relative to an imaginary line normal to a front surface of the cutting head from which the cutting teeth project. Such an arrangement provides the desired shear cutting force against the rock face while simultaneously reducing the shock and vibration applied to sonde housing and the drill string. The bit according to the invention may further incorporate a rear, frustoconical crushing surface that defines a space or zone crescent-shaped in cross-section that narrows from front to rear, and an improved replacable tooth for use on a rock drilling bit.