Patent Publication Number: US-2022228441-A1

Title: Horizontal Directional Reaming

Description:
TECHNICAL FIELD 
     The disclosure relates to the field of horizontal directional drilling or reaming techniques and equipment for drilling holes or boreholes for installation of pipe underground or under obstacles, such as a body of water. 
     BACKGROUND 
     Cone-shaped drill bits or cones or cutters have been used to make bore or hole enlargement tools called reamers or hole openers. A split-bit reamer is a type of reamer featuring cones or cone drill bits. The split-bit reamer is a tool often of larger diameter and is of particular use in horizontal directional drilling applications. 
     Some examples of prior art cone drill bits and split-bit reamers are shown in  FIG. 1 ,  FIG. 2  and  FIG. 3 . 
       FIG. 1  shows a typical drill bit third (i.e. of a tri-bit drill head) or reamer cone and arm/leg, which is cutting element with an arm and a rotating cone. The intersection of the dashed lines M &amp; N shows the center of rotation O for the cone along the tool axis of rotation or axle. The typical drill bit third or reamer cone represented is rounded at its apex (i.e. at a distance D which does not coincide with the center of rotation of a prior art split-bit reamer). 
       FIG. 2  shows five cones of drill bits mounted forming a split-bit reamer. Each drill bit cone represented in  FIG. 2  (five shown) is a solid body and is not segmented and it may have or not surface lines or grooves showing a step-like exterior substantially conical body all as one unitary body upon which the cutting teeth are mounted in rows. The center of rotation of one of the five cone drill bits is marked in the drawing with a plus (+) sign X (located off-center of the center of rotation Y of the reamer). The center of rotation of the reamer Y along its axis of rotation is also marked with a plus (+) Y sign (located as the center of the reamer) in the drawing. The center of rotation of the drill bit cone X (O in  FIG. 1 ) is distant from the center of rotation Y for the reamer leading to friction of drag. The distance between the center of rotation of a cone X (or O) and the center of rotation of the reamer Y becomes more exaggerated or greater the larger the diameter of the reamer tool. 
       FIG. 3  shows a typical internal bearing mechanism between an arm of a split-bit reamer cutter and the typical cone. The bearing mechanism can only feature small, weaker bearings proximate the apex of the cone due to the shape of the cone (.i.e. the narrow area or volume proximate the apex of the cone due to its angularity only allows room for smaller and/or shorter cylindrical bearings). 
     The prior art cones and split-bit reamer create mechanical inefficiency at the cones. The drill bit cones do not and cannot match at each respective row of teeth the rotational speed of the overall reamer around their axles, and hence the tangential speed at the cone surface of the drill bit cone cannot be efficiently matched or correlated with the tangential speed due to the rotation around the longitudinal axle of the split-bit reamer as further described below. 
     When a cone drill bit rotates around the axle of a reamer due to the application of a force on the tool, e.g. via drilling mud/fluid, (this force is the driving factor for the reamer to drill through earth, ground or rock), every tooth on the cone will have a tangential speed, determined by the angular speed or rotational speed of the cone. Since the tangential speed depends on the angular speed and the radius, due to the triangular cross-sectional shape of the cone, the teeth that are farther away or mounted at a greater radial distance from the axle of the cone will have a higher tangential speed than the teeth close to the “tip” of the cone. The teeth located at a farther distance from the axle, i.e. the ones close to the “base” of the cone and referred to as gauge teeth, will create a higher momentum than the teeth located closer to the axle of the cones, i.e. the teeth closer to the “tip” of the cone, once a friction force is created in between each respective tooth and the earth, ground or rock that is being drilled (reamed). 
     Due to this momentum&#39;s difference, the gauge teeth will establish the rotational speed of the cone, trying to match their tangential speed around the cone&#39;s axle with the tangential speed according to their position on the reamer. This creates significant mechanical inefficiency. The teeth closer to the tip of the cones do not have enough tangential speed around the cone&#39;s axle to match the tangential speed established by the rotation of the reamer. As a consequence of this inefficiency, the teeth successively and relatively closer to the tip of the cones have imperfect contact with the earth, ground, or rock which causes teeth to skid or drag over the rock, inefficiently scratching or scrapping its surface and often ineffectively drilling or crushing the earth, ground, or rock. The inefficiency may be especially disruptive in situations where the geological material being reamed comprises rock or hard rock. The mechanical inefficiency giving rise to scratching or scraping action, instead of a crushing action, causes teeth successively and relatively closer to the tip of the cones to become flat (worn) sooner than the gauge teeth. 
     When teeth become flat, the rate-of-penetration (“ROP”) of the reamer or the speed at which the reamer drills through the earth, ground or rock decreases. When the ROP reaches the minimum acceptable value, it forces the driller or operator to trip out the reamer to change it with another unit. The lifetime of the reamer and the ROP of the reamer are negatively affected by this mechanical inefficiency. Additionally, the greater the distance between the center of rotation of a cone and the center of rotation of the reamer, the greater or more pronounced is the mechanical inefficiency. 
     Examples of back reaming are included in US Patent Publication No. 2014/0338984 and U.S. Pat. No. 7,243,737 which are herein incorporated by reference in their entireties. 
     BRIEF SUMMARY 
     The desired concept of reaming the earth, ground, or rock with drill bits or reamer heads should be that every tooth will be pushed against the rock producing a crushing effect, and that the combination of the rotational movement plus the injection of drilling fluid at high speed will evacuate the pieces of crushed rock, called cutting, leaving the surface of the rock clean for the next tooth to repeat the process. The present disclosure relates to embodiments of horizontal directional drilling equipment and methods for horizontal directional drilling techniques which more efficiently achieve the desired crushing effect. 
     The present disclosure relates to embodiments of an improved reamer head or apparatus for reaming an underground arcuate path having a reaming head in one embodiment as a frustoconical or truncated cone, or conical frustum shape or substantially frustoconical, truncated cone, conical frustum shape, or frustoconical body. An imaginary apex of the frustoconical body is superimposed on the centerline of a reamer or reaming apparatus for reaming of an underground arcuate path. 
     Further, the present disclosure relates to embodiments of a reamer apparatus for reaming an underground arcuate path or split-bit reamer featuring in one embodiment a plurality of improved reamer heads having a frustoconical, truncated cone, or conical frustum shape or substantially frustoconical, truncated cone, or conical frustum shape. 
     Additionally, the present disclosure relates to embodiments of an improved bearing mechanism for a reamer arm and reamer head. 
     The present disclosure also relates to embodiments of an apparatus for reaming an underground arcuate path or roller cone reamer head or progressive independently segmented reaming head. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The embodiments may be better understood, and numerous objects, features, and advantages made apparent to those skilled in the art by referencing the accompanying drawings. These drawings are used to illustrate only typical embodiments of this invention, and are not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness. 
         FIG. 1  shows an exploded view of a ‘Prior Art’ drill bit and arm. 
         FIG. 2  shows a schematic view along the axis of rotation of a ‘Prior Art’ reaming apparatus or reamer having drill bit cones as reaming heads. 
         FIG. 3  shows a partial sectional view of a ‘Prior Art’ bearing mechanism in combination with a drill bit cone as a reaming head. 
         FIG. 4  depicts a schematic elevation view of an exemplary embodiment of a reamed hole crossing along an underground arcuate path after a prior drilled and/or reamed hole crossing. 
         FIG. 5  shows an exploded view of an exemplary embodiment of an improved reaming head and arm. 
         FIG. 6  shows a perspective view of an exemplary embodiment of a split-bit reamer or reaming apparatus featuring mounted improved reaming heads. 
         FIG. 7  shows a schematic view along the axis of rotation of an exemplary embodiment of a split-bit reamer featuring mounted improved reaming heads. 
         FIG. 8  shows a side view of an exemplary embodiment of a progressive independently segmented reaming head mounted to an arm of a split-bit reamer. 
         FIG. 9  shows a partial sectional view of an exemplary embodiment of an improved bearing mechanism  90  between an arm  34  of a split-bit reamer (not shown) and an improved reaming head (not shown). 
         FIG. 10  shows a partial view of a typical largest size bearing assembly journal used for the mount of a drill bit cone. 
         FIG. 11  shows a partial view of an exemplary embodiment of an improved reaming head journal having increased flange thickness. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The description that follows includes exemplary apparatus, methods, techniques, and instruction sequences that embody techniques of the inventive subject matter. However, it is understood that the described embodiments may be practiced without these specific details. 
     Referring to  FIG. 4 , the hole  52  is reamed by the reamer  50  to make a larger hole  54 . A pilot hole (not shown or potentially  52 ) is drilled to begin a crossing. The pilot hole may be reamed after drilling to make an intermediate or relatively larger hole  52 . The intermediate hole  52  is reamed against walls  53  by reamer  50  to make a larger hole  54 . The reamer  50  was dispatched from the rig  61  opposite drilling rig  60  and drills the arcuate path or crossing  54  through the earth  10  and may cross beneath an obstacle  12  such as, for example, a body of water, a transportation way, etc. 
       FIG. 5  shows an exploded view of an exemplary embodiment of an improved reamer head  30  and split-bit reamer arm  34 . The improved reamer head  30  has a frustoconical, truncated cone (via truncated end  33 ), or conical frustum shape or substantially frustoconical, truncated cone, conical frustum shape, or frustoconical body  32 . The improved reamer head  30  has teeth  38 . The improved reamer head  30  rotates about its center axis  36  and has center of rotation, located at its imaginary apex/geometrical  40 , which can/will align with the center of rotation or centerline  56  of a split-bit reamer (not shown in  FIG. 5 , but represented in  FIG. 6 or 7 ) for reducing friction/drag externally as the reamer  50  moves into/through the hole  52  and circumferentially reams surrounding walls  53  (causing friction/drag) to create a larger hole  54 . The imaginary/geometrical apex  40  is the apex of imaginary/geometrical conical surfaces  39   a ,  39   b  of improved reamer head  30 . The imaginary/geometrical conical surfaces  39   a ,  38   b  may be an imaginary/geometrical projection or extrapolation based upon the shape (e.g. frustoconical, truncated cone, or conical frustum shape or substantially frustoconical, truncated cone, or conical frustum shape) of improved reamer head  30  (or more specifically of frustoconical body  32 ) and defines an imaginary/geometrical conical shape  41 . As the radius of the frustoconical or truncated conical body  32  varies along its height, the imaginary/geometrical apex  40  (omitted from the frustoconical body  32 ) can be matched to or mounted to be coincidental with (or superimposed upon) the center of rotation at  40  (along centerline  56 ) of the fully assembled reaming apparatus. Each reamer head  30  defines a center cavity or bore  35  (generally shown in  FIG. 5  and  FIG. 9 ) for mounting on arm  34  that may accommodate bearings  92 ,  94 ,  96  (see  FIG. 9 ) or have a bearing surface (not shown) for mounting on and rotation about the arm  34 . 
     In  FIG. 5 , in one embodiment, the frustoconical body  32  may be about sixty-five to seventy-five percent relative to the size or volume of a full cone (i.e. as defined by the imaginary/geometrical conical shape  41 ). 
       FIG. 6  shows a perspective view of an exemplary embodiment of a split-bit reamer or reaming apparatus  50  featuring mounted improved reaming heads  30 . The split-bit reamer  50  may be attached to a reamer line  59  through which muds or drilling fluids (not shown) travel. The exemplary embodiment of the split bit reamer  50  shown usually has a centralizing ring or shroud  58  connected to the body  51  of the split-bit reamer  50 , with a plurality of arms  34  extending from the body  51 , wherein an improved reaming head  30  is mounted to each of the plurality of arms  34 . The split-bit reamer  50  rotates about its centerline or central axis  56  (defined by the split-bit reamer  50  and/or the reamer line  59 ). 
       FIG. 7  shows a schematic view along the axis of rotation of an exemplary embodiment of a split-bit reamer  50  featuring mounted and symmetrically arranged improved reaming heads  30  and centralizing ring  58 . The center of rotation at imaginary/geometrical apex  40  (along center axis  36 ) for each of the improved reaming heads  30  aligns or coincides (i.e. at a distance L represented in  FIG. 5 ) with the center of rotation of the reamer  80  along the reamer centerline axis  56  (shown in  FIG. 6 ). In other words, the center axis  36  of each respective reaming head  30  intersects the reamer centerline axis  56  coinciding with the imaginary/geometrical apex  40  at center of rotation of the reamer  80 . 
       FIG. 8  shows a side view of an exemplary embodiment of a progressive independently segmented reamer head  130  mounted to an arm  134  of a split-bit reamer (not shown but mounted similar as represented in  FIG. 2 ). This exemplary embodiment of a progressive independently segmented reaming head  130  comprises stacked, annular segments or pieces  132  which are collectively mounted to form a cone or conical shape or substantially cone shape  131 . Each of the respective stacked, annular segments or pieces  132   a - e  may each be truncated cones or frusto-conical shaped or conical frustums all varying sequentially in radius along the height of the progressive independently segmented reamer head  130 . The segment  132   e  at the apex of the cone shape  131  or the tip of the reamer head may be conical or substantially conical (or may alternatively annular similar to other segments, yet having the smallest radius that varies along its height). The stacked pieces  132  have a consecutively larger diameter along the height or length of the reamer head  130  (starting from the apex) and independently rotate on a center shaft (not shown) in forming the cone-shaped  131  progressive independently segmented reaming head  130 . Each of the independently rotational and stacked annular truncated conical segments  132   a - e  respectively has a plurality of teeth  138  mounted thereon. Each of the respective stacked, annular segments or pieces  132   a - e  has a center bore (not shown) for mounting on arm  134  that may accommodate bearings (not represented in  FIG. 8 ) or have a bearing surface (not shown) for mounting on and rotation about the arm  134 . It is to be appreciated that each of the respective stacked, annular segments or pieces  132   a - e  may independently rotate (subject to any frictional forces) for reducing friction/drag externally as the reamer  50  moves into/through the hole  52  and circumferentially reams walls  53  (causing friction/drag) to create a larger hole  54 . 
       FIG. 9  shows a partial sectional view of an exemplary embodiment of an improved bearing mechanism  90  between an arm  34  of a split-bit reamer  50  (shown in  FIGS. 6-7 ) for mounting of an improved reaming head  30  (shown in  FIGS. 5-7 ). The improved bearing mechanism  90  in this sectional view includes an upper cylindrical bearing  94  and a lower cylindrical bearing  92 , and in one embodiment, each of the cylindrical bearings  92 ,  94  being the same size or substantially the same size (this is to be contrasted with  FIG. 3  and its related discussion above; note in  FIG. 9  bearing  92  is relatively longer as compared/contrasted to  FIG. 3  bearings proximate the apex due to the reduction of angularity in the embodiments of  FIGS. 5, 6, 7 &amp; 9 , e.g. by way of example only, 5°-25° reduction of angularity). The angularity and design of the bearings is matched to fit the embodiments represented in  FIGS. 5-7 . The length of the upper cylindrical bearing  94  relative to the lower cylindrical bearing  92  is not necessarily drawn to scale in  FIG. 9  but shown schematically and it is to be appreciated they may be of substantially the same length and/or width. 
     Related to the bearing mechanism  90 , horizontal directional drilling has many unique challenges specific to the industry. Because it is very often large diameter and mainly works horizontal or near horizontal, a horizontal directional drilling reaming assembly/split-bit reamer  50  has a significant amount of weight and thus is subject to considerable lateral forces (forces that are not exerted on the cutting face  62  [shown schematically in  FIG. 4 ] of the split-bit reamer tool  50 , but on the lower lateral side  64  of its body  51 ). The most important unique challenge is the lateral forces which significantly affect how a horizontal directional drilling split-bit reaming tool  50  works and how a horizontal directional drilling reaming tool  50  wears over time. Additionally, other unique challenges are the stresses on a horizontal drill pipe and the relatively large diameter of a horizontal reamed bore  54 . In essence the geometry of the reamer heads  30  in relation to the centerline axis  56 , as described above with respect to  FIG. 7 , allows a uniform workload on the different rows of teeth  38  (every tooth, independently in what row is located, will be crushing the same amount of rock than any other tooth in the reamer head  30 ) resulting in the advantage of generating an increment in the rate of penetration of the horizontal directional drilling reaming apparatus  50  as well as extending its lifetime. This geometry of the reamer heads  30  in relation to the centerline axis  56 , as described above with respect to  FIG. 7 , also allows the incremental thickness T of the bottom flange  198  of the reaming head journals  190  (see  FIG. 11 , the reaming head journals  190  are the pieces that protrude from the arms  34  and that run through the internal cavity of the reamer head roller cones  30 —along the axis  36  that holds the reamer head roller cones  30  in position and serve as an internal race for the bearing mechanism  90  allowing the reamer head cones  30  to rotate). This flange T is important because, as previously mentioned, in horizontal directional drilling the lateral forces exerted across lateral sides  64  on the reamer head&#39;s cones  30  are always high which can lead to catastrophic failure or breakage. These forces are mainly due to the overall weight of the HDD reaming tool/apparatus  50  (the reamer head cones  30  and bearing mechanism  90  components that at a given time are located under or falling on the lower side or region  64  of the assembled HDD reaming tool/apparatus  50  must support the full weight of the overall assembled reaming tool  50 ). In standard vertical oil drilling these lateral forces are relatively significantly smaller if compared with the lateral forces exerted in horizontal directional drilling, and the diameters at which the holes are drilled are relatively much smaller comparative to the diameter  54  of horizontal directional drilling reaming, therefore, the weight of the respective hole openers is completely different. 
       FIG. 11  shows a partial view of an exemplary embodiment of an improved reaming head journal  190  for the bearing mechanism  90  (shown in  FIG. 9 ) from the arm  34  of a split-bit reamer  50  (shown in  FIGS. 6-7 ). The improved reaming head  30  (shown in  FIGS. 5-7 ) is mounted over the reaming head journal  190  with the bearing mechanism  90  interposed or there-between the reaming head journal  190  and the reaming head  30 . The reaming head journal  190  has a lower journal bearing seat  192  for abutting or contiguous with the lower cylindrical bearings  92 , an upper journal bearing seat  194  for abutting or contiguous with the upper cylindrical bearing  94 , and an intermediate journal bearing/retaining seat  196  for abutting or contiguous with the retaining spheres/ball bearings  96 . The reaming head journal  190  includes a flange  198  defined between one end  197  of the intermediate journal bearing/retaining seat  196  and another end  195  of the lower journal bearing seat  192  (the flange  198  supports and is contiguous with retaining spheres/balls bearings  96  and lower cylindrical bearings  92  when the reaming head  30  is mounted on the reaming head journal  190 ). The distance T between one end  197  of the intermediate journal bearing/retaining seat  196  and another end  195  of the lower journal bearing seat  192  defines the thickness T of the flange  198 . The thickness T of the flange  198  must support the lateral forces applied to the reamer  50 , and support thrust on the reaming head  30 , all as translated through the retaining spheres/ball bearings  96 . 
     Various example diameters for the horizontal directional drilling (“HDD”) reaming operations are 91.44 cm (36 inches) diameter, 106.68 cm (42 inches), 121.92 cm (48 inches), 137.16 cm (54 inches), and a 152.4 cm (60 inches) diameter. These examples may cover about eighty percent of the Applicant&#39;s reaming operations, and the larger or widened diameter HDD reamed hole  54  may be dependent upon the standard pipeline size to be finally installed in the widened HDD reamed hole  54 . 
     In one working example in which the HDD reamer operation is designed to ream at least a 121.92 cm (48 inches) path or widened reamed hole  54 , the full weight of the overall assembled reaming tool  50  may be approximately 5443 kilograms (12,000 lbs.), the flange thickness T may be about 2.286 centimeters (0.9 inches). This flange thickness T of 2.286 cm (0.9 inches) represented generally in  FIG. 11  is to be compared and contrasted to the standard thickness H of about 1.38938 cm (0.547 inches) represented in  FIG. 10  ( FIG. 10  shows a partial view of a typical ‘largest size’ bearing assembly journal used for the mount of a drill bit cone). Therefore, the flange thickness T is at least fifty percent (50%) thicker than the standard thickness H, and in the case of the 121.92 cm (48 inch) diameter reaming apparatus  50  the flange thickness T is sixty-four percent (64%) thicker than the standard thickness H (i.e. compare and contrast  FIG. 10  to  FIG. 11 ). As previously mentioned, in horizontal directional drilling the lateral forces exerted across lateral sides  64  on the reamer head&#39;s cones  30  are always high which can lead to catastrophic failure or breakage; and in the exemplary embodiment discussed the retaining spheres/balls bearings  96  will exert force on the flange  198  due to the lateral forces (including the weight of the overall assembled reaming tool  50  being approximately 5443 kilograms (12,000 lbs.) in the specific example discussed). Hence, the flange thickness T may be critical to the durability and efficiency of the assembled HDD reaming tool apparatus  50 . 
     In a second representative working example in which the HDD reamer operation is designed to ream at least a 91.44 cm (36 inches) path/widened reamed hole/underground arcuate path  54  the overall assembled reaming tool  50  mass may be approximately 1723.65 kilograms (3,800 lbs.) which correlates to the flange thickness T as described above which is at least fifty percent (50%) thicker than the standard thickness H. 
     In a third representative working example in which the HDD reamer operation is designed to ream at least a 106.68 cm (42 inches) path/widened reamed hole/underground arcuate path  54  the overall assembled reaming tool  50  mass may be approximately 3583.38 kilograms (7,900 lbs.) which correlates to the flange thickness T as described above which is at least fifty percent (50%) thicker than the standard thickness H. 
     In a fourth representative working example in which the HDD reamer operation is designed to ream at least a 137.16 cm (54 inches) path/widened reamed hole/underground arcuate path  54  the overall assembled reaming tool  50  mass may be approximately 6032.78 kilograms (13,300 lbs.) which correlates to the flange thickness T as described above which is at least fifty percent (50%) thicker than the standard thickness H. 
     In a fifth representative working example in which the HDD reamer operation is designed to ream at least a 152.4 cm (60 inches) path/widened reamed hole/underground arcuate path  54  the overall assembled reaming tool  50  mass may be approximately 6713.17 kilograms (14,800 lbs.) which correlates to the flange thickness T as described above which is at least fifty percent (50%) thicker than the standard thickness H. 
     The foregoing addresses that problems due to the teeth  38  relatively closer to the tip/apex  40  proximate truncated end  33  of the reamer heads  30  do not have enough tangential speed around the cone&#39;s axle  36  to match the tangential (circumferential) speed established by the rotation of the HDD split-bit reaming tool apparatus  50 . As a consequence of this significant mechanical inefficiency, the teeth  38  successively and relatively closer to the apex  40  proximate truncated end  33  of the reamer heads  30  have imperfect contact with the earth, ground, or rock which causes teeth  38  to slide or drag over the rock, inefficiently scratching or scrapping its surface and often ineffectively drilling or crushing the earth, ground, or rock. This produces an effect of skidding over the rock face instead having a perfect contact and causes teeth  38   a  successively and relatively closer to the apex  40  proximate truncated end  33  of the reamer heads  30  to become flat (worn) sooner than the gauge teeth  37 . Hence, the problem lies in that [t]he mechanical inefficiency is due to the fact that the tangential (circumferential) speed of the teeth  38  closer to the apex  40  proximate truncated end  33  of the reamer head  30  is lower than the required speed relative to their position on the HDD split-bit reaming tool apparatus  50 . Since the tangential speed of the teeth  38  depends on the angular speed of the reamer head  30  and the radius from the cone axle  36  at what the respective teeth  38  are located, due to the triangular cross-sectional shape  39   a ,  39   b  of the cone (imaginary/geometrical conical shape  41 ), the teeth that are farther away or mounted at a greater radial distance from the axle  36  of the cone will have a higher tangential speed than the teeth close to the “tip/apex”  40  proximate truncated end  33  of the reamer heads  30 . The teeth  37  located at a farther distance from the axle, i.e. the ones close to the “base” of the cone and referred to as gauge teeth  37 , will create a higher momentum than the teeth  38  located closer to the axle  36  of the reamer head  30 , i.e. the teeth relatively closer to the “tip/apex”  40  of the cone, once a friction force is created in between each respective tooth  38  and the earth, ground or rock that is being drilled (reamed). Due to this relative difference in momentum, the gauge teeth  37  will predominantly establish the rotational speed of the reamer head  30 , which is the reason for the gauge row being named “driver row” by those skilled in the art (usually, the “perfect” rotation speed is located in an area in between the gauge row and the near gauge row, which are, the first and second rows starting from the “base” of the cone). 
     Additionally, the skidding explains why larger hole reaming operations require more torque to rotate the HDD reaming apparatus  50 . This skidding creates frictional forces at a certain distance from the axis  56  of the hole opener, creating torque, which further compounds problems contributing to a decrease in the rate of penetration into the hole/underground arcuate path  54  to be reamed. In essence skidding results in a need for greater torque to rotate the HDD reaming apparatus  50 ; results in premature wear of the teeth  38  by the friction against the rock; increases the torsional forces exerted on the arms  34  that hold the reamer heads  30 ; and reduces the rate of penetration of the HDD reaming apparatus  50 , plus increases the likelihood of catastrophic failures. 
     It is understood that the present disclosure is not limited to the particular applications and embodiments described and illustrated herein, but covers all such variations thereof as come within the scope of the claims. While the embodiments are described with reference to various implementations and exploitations, it will be understood that these embodiments are illustrative and that the scope of the inventive subject matter is not limited to them. Many variations, modifications, additions and improvements are possible. 
     Plural instances may be provided for components, operations or structures described herein as a single instance. In general, structures and functionality presented as separate components in the exemplary configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements may fall within the scope of the inventive subject matter. 
     The reference numbers in the claims are not intended to be limiting in any way nor to any specific embodiment represented in the drawings, but are included to assist the reader in reviewing the disclosure for purposes of a provisional filing.