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BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The invention relates generally to an auger boring machine and a method of use in the trenchless installation of underground pipe. More particularly, the invention relates to such a machine which utilizes a pilot tube for forming a pilot hole for guiding the auger of the machine. Specifically, the invention relates to a two-stage guidance control system for guiding the pilot tube through the earth to form a pilot hole which is several hundred feet long. 
         [0003]    2. Background Information 
         [0004]    The use of an auger boring machine for installing underground pipe between two locations without digging a trench there between is broadly known. In addition, it is known to use a pilot tube formed of a plurality of pilot tube segments to create a pilot hole for guiding an auger which bores a larger hole so that the auger remains within a reasonably precise line and grade. For example, see U.S. Pat. No. 6,206,109 granted to Monier et al. Commonly, a theodolite is used to control the line and grade of the pilot tube in forming the pilot hole. However, the theodolite system has limitations in that when the pilot hole extends past a certain distance, usually in the range of about 400 feet, the illuminated target adjacent the pilot tube is too far away to be properly sensed from the area of the pilot drive assembly. Thus, in forming pilot holes which are extremely long, there is a need for a guidance control system to ensure that the remaining portion of the pilot hole remains on line and grade. The present invention solves this and other problems in the art. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    The present invention provides an apparatus comprising: an auger boring machine pilot tube; a first stage guidance control mechanism for guiding the pilot tube during a first stage of driving the pilot tube; and a second stage guidance control mechanism for guiding the pilot tube during a second subsequent stage of driving the pilot tube. 
         [0006]    The present invention further provides a method comprising the steps of: (a) sensing a position of an auger boring machine pilot tube with a first sensing device during a first stage of driving the pilot tube to form a pilot hole in the ground; (b) guiding the pilot tube during the first stage of driving the pilot tube in response to step (a); (c) sensing a position of the pilot tube with a second sensing device during a second subsequent stage of driving the pilot tube; and (d) guiding the pilot tube during the second stage of driving the pilot tube in response to step (c). 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0007]      FIG. 1  is a side elevational view of the auger boring machine of the present invention shown in a pit formed in the earth. 
           [0008]      FIG. 2  is a top plan view of the auger boring machine. 
           [0009]      FIG. 3  is a perspective view of the drive and control assembly. 
           [0010]      FIG. 4  is a fragmentary sectional view showing a pilot tube segment with the LED target disposed therein and connected to the sonde segment and a trailing pilot tube segment.  FIG. 4  also illustrates the flow of lubricant through these segments of the pilot tube. 
           [0011]      FIG. 5  is a sectional view taken on line  5 - 5  of  FIG. 4  showing the LED target within the pilot tube. 
           [0012]      FIG. 6  is a side elevational view of the sonde segment of the pilot tube. 
           [0013]      FIG. 7  is a sectional view taken on line  7 - 7  of  FIG. 6  and also includes the connection of the sonde segment to the steering head and the pilot tube segment which houses the LED target. 
           [0014]      FIG. 8  is a sectional view taken on line  8 - 8  of  FIG. 7 . 
           [0015]      FIG. 9  is a sectional view taken on line  9 - 9  of  FIG. 8 . 
           [0016]      FIG. 10  is a top plan view of the pilot tube drive assembly prior to formation of the pilot hole. 
           [0017]      FIG. 11  is a top plan view of the drive assembly showing an extension of the hydraulic actuators to provide an initial stage of pilot hole formation and also showing the steering capability of the pilot tube. 
           [0018]      FIG. 12  is similar to  FIG. 11  and shows the subsequent pilot tube segment connected to the previously driven pilot tube segment and the drive mechanism. 
           [0019]      FIG. 13  is similar to  FIG. 12  and shows the extension of the hydraulic actuators of the drive mechanism to drive the pilot tube with the newly installed pilot tube segment thereof to lengthen the pilot hole. 
           [0020]      FIG. 14  is a diagrammatic view showing the second stage of the guidance control system in which the sonde transmits a signal to a receiver above ground. 
       
    
    
       [0021]    Similar numbers refer to similar parts throughout the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    The auger boring machine of the present invention is indicated generally at  10  in  FIGS. 1 and 2 . Referring to  FIG. 1 , machine  10  is typically disposed in a pit  6  formed in the earth&#39;s soil or ground  8  and configured to bore a hole through ground  8  for the purpose of laying underground pipe in the bored hole. Machine  10  typically bores a hole from within a pit such as pit  6  to another pit which is spaced several hundred feet away. Machine  10  includes a frame  12  which extends from a front end  14  to a rear end  16  of machine  10 . Front and rear end  14  and  16  define there between an axial direction of machine  10 . Machine  10  further has first and second opposed sides  18  and  20  ( FIG. 2 ) defining there between a lateral direction of machine  10 . 
         [0023]    An engine compartment  22  is mounted on frame  12  and houses therein a fuel powered engine  24 , an electric generator  26  powered by engine  24  and a hydraulic pump  28  also powered by engine  24 . An auger drive compartment  30  is disposed in front of compartment  22  and houses therein an auger drive having a rotational output shaft  32  for rotationally driving an auger  34  ( FIG. 25 ). Frame  12  further includes a pair of spaced axially extending rails  36  secured to a plurality of cross bars  38  which are mounted on ground  8  in the bottom of pit  6 . A pair of adjustable stabilizing poles  40  are telescopically received in and adjustably mounted respectively on rails  36  and configured to press against the wall of ground  8  which bounds pit  6 . 
         [0024]    In accordance with a feature of the invention, a two-stage pilot tube guidance control and drive assembly  42  is mounted on frame  12 , and more particularly is removably mounted on rails  36  via mounting legs  44  ( FIG. 3 ) which are removably insertable into openings  46  formed in each of rails  36 . Mounting legs  44  and the mounting mechanism of which they are a part are described in further detail in the copending application entitled Pilot Tube System And Attachment Mechanism for Auger Boring Machine which is incorporated herein by reference and filed concurrently herewith. Assembly  42  when mounted on frame  12  is positioned so that a central axially extending axis X of a pilot tube  48  is coaxial with an axially extending axis Y which passes centrally through output shaft  32  and about which shaft  32  is rotated when driving an auger and cutting head (not shown). Assembly  42  includes a generally circular rear plate  50  which abuts compartment  30  when assembly  42  is mounted on frame  12 . 
         [0025]    Assembly  42  includes front and rear mounting assemblies  52  and  54  which are seated on rails  36  of frame  12  when assembly  42  is mounted on frame  12 . A pair of axially extending parallel spaced rails  56  and  58  are rigidly mounted on assemblies  52  and  54 . Adjustable stabilizing poles  60  are telescopically mounted respectively within first and second rails  56  and  58  and are adjustable to provide force against ground  8  in the same manner as poles  40 . 
         [0026]    A rigid front cross member  62  extends between and is connected to each of rails  56  and  58  adjacent the front thereof with a front pilot tube support  64  mounted thereon centrally between rails  56  and  58 . Support  64  includes a plurality of bearings which engage the pilot tube  48  to allow axial movement of tube  48  as well as rotational movement of tube  48  about axis X to allow for the steering thereof. Rear plate  50  and associated structure attached thereto serve as a rear cross member for rigidly connecting rails  56  and  58  to one another at the rear of assembly  42 . An intermediate cross member  66  extends laterally between rails  56  and  58  and is supported respectively on rails  56  and  58  by first and second roller assemblies  68  and  70 . Each roller assembly includes a pair of upper rollers  72  and lower rollers  74  which respectively rollingly engage upper and lower surfaces  76  and  78  of respective rails  56  and  58 . 
         [0027]    An electric guidance control motor  80  having a rotational drive is mounted on cross member  66  for selectively rotating pilot tube  48  in either direction about axis X. A lubricant feed swivel  82  having a lubricant inlet  84  is mounted on motor  80  by a pair of spaced mounting rods  86  extending forward from motor  80 . Swivel  82  is connected to pilot tube  48  and thus serves as an engaging member for drivingly engaging tube  48  during operation of assembly  42 . Inlet  84  of swivel  82  is in fluid communication with a lubricant feedline which is in fluid communication with a source of lubricant, which is typically water. Swivel  82  receives water through inlet  84  to pump the water through pilot tube  48  and through a steering head  88  connected to the front of pilot tube  48 , the water flowing out a forward exit opening  90  and a plurality of lateral exit openings  92 . A crane stand  94  is mounted on the frame of assembly  42  for supporting a crane (not shown) used for lifting pilot tube segments into position for connecting the various segments to form pilot tube  48  during the process of driving tube  48  to form the pilot hole. A cord carrier  96  is mounted atop rail  56  and includes a plurality of links  98  which are pivotally connected to one another so that electrical cords for powering motor  80  and other electrical components will not become tangled during the longitudinal driving of pilot tube  48 . 
         [0028]    In accordance with the invention, during the first stage of driving pilot tube  48 , a steering mechanism keeps tube  48  on line and grade using a theodolite which utilizes a camera  100  in electrical communication with a display monitor  102  which displays the view of the camera through pilot tube  48  of an illuminated LED target  104  ( FIGS. 4-5 ) disposed within pilot tube  48  adjacent steering head  88 . In order for camera  100  to view light rays transmitted from LED target  104 , pilot tube  48  is hollow, as are the other structures intermediate camera  100  and target  104 , such as motor  80  and swivel  82 , in order to provide a line of sight Z ( FIGS. 4 ,  11 ,  13 ) between camera  100  and target  104 . A guidance control unit  106  is mounted on rail  58  and includes manually operable controls  108  typically in the form of joysticks in electrical communication with motor  80  in order to send a signal to motor  80  to control rotation of pilot tube  48 . 
         [0029]    Assembly  42  includes a continuous stroke drive mechanism  110  comprising a pair of hydraulic actuators in the form of piston-cylinder combinations  112  powered by pump  28 . Combinations  112  must provide a substantial amount of forward and reverse thrust. For example, the forward thrust produced by combinations  112  on one preferred embodiment has a maximum thrust of 280,000 pounds while the reverse thrust has a maximum thrust of 140,000 pounds. Combinations  112  are capable of a continuous stroke throughout the extension thereof and likewise during the retraction thereof. The continuous stroke drive mechanism of the present invention is described in further detail in the copending application entitled Method And Apparatus For Providing A Continuous Stroke Auger Boring Machine which is incorporated herein by reference and filed concurrently herewith. 
         [0030]    In accordance with the invention, pilot tube  48  includes a target-containing pilot tube segment  122  and a sonde segment  125  removably connected to the leading end of segment  122  and the trailing end of steering head  88 . The various pilot tube segments of pilot tube  48  are connected end to end to sequentially increase the length of pilot tube  48  during the driving process. Typically, all or nearly all of the pilot tube segments are of the same length and are interchangeable with one another. However, some of the pilot tube segments may be of a different length. Segments  122  and  125  are shorter than the standard pilot tube segments  124  connected sequentially behind segment  122 . Pilot tube segment  122  has a length of roughly two feet while segment  125  is roughly three feet long and pilot tube segments  124  typically come in lengths of five feet although this may vary. 
         [0031]    As noted previously, pilot tube  48  is configured with lubricant through passages to allow a lubricant such as water to flow therethrough to steering head  88 . The lubrication system of assembly  42  is described in further detail in the copending application entitled Lubricated Pilot Tubes For Use With Auger Boring Machine Pilot Steering System which is incorporated herein by reference and filed concurrently herewith. However, some of the lubricant passages of pilot tube  48  are discussed herein. More particularly,  FIG. 5  shows a sectional view of a trailing portion of sonde segment  125 , segment  122  and a leading portion of a pilot tube segment  124 , which in part shows the lubricant passages therethrough. Segment  122  has a first trailing coupling member  130  which threadably engages a second leading coupling member  132  of the leading segment  124  to connect segments  122  and  124  together. Six lubricant passages  140  are formed in first coupling member  130  and are circumferentially equally spaced from one another. A central through passage  162  is formed in pilot tube segment  124 . Six lubricant passages  164  are also formed in segment  124  radially outwardly of passage  162  and are circumferentially evenly spaced from one another in order to align with passages  140  when first and second coupling members  130  and  132  are joined to one another. 
         [0032]      FIG. 5  shows additional passages in pilot tube  48  allowing for a flow of lubricant therethrough to steering head  88 . More particularly, six lubricant passages  172  are formed through segment  122  in a manner similar to passages  140  and passages  164  in order to allow communication with passages  140  of coupling member  130 . Passages  172  are disposed radially outwardly of a central interior chamber  173  which is formed in segment  122  and which houses target  104 . Passages  172  merge into a central chamber  174  formed in the rear portion of sonde segment  125  via respective passages  176  which extend radially outwardly from chamber  174 .  FIG. 4  further shows that lead tube segment  122  defines a central passage providing for line of sight Z therethrough to provide a clear view of illuminations  180  ( FIG. 5 ) of target  104 . 
         [0033]    Referring to  FIGS. 6-9 , sonde segment  125  and steering head  88  are further described. Segment  125  has a substantially solid cylindrical main body  134  which makes up most of its length. Body  134  has a leading end  136  and a trailing end  138  with a mounting neck  140  extending rearwardly from trailing end  138 . Neck  140  is stepped inwardly from body  134  and is also substantially cylindrical. Neck  140  defines a pair of axially spaced annular grooves in which are disposed a respective pair of annular seals  142 . Neck  140  further defines an annular groove  143  between seals  142  in communication with each of passages  176 . A neck-receiving cavity  144  is formed in body  134  and extends rearwardly from leading end  136  for receiving therein a neck  146  of steering head  88  which is similar to neck  140  of segment  125 . Body  134  defines a central transmitter cavity  148  which is in communication with cavity  144  and in which a radio frequency (RF) transmitter  150  is disposed. Six axially elongated transmission slots  152  are formed in body  134  and extend radially outwardly from cavity  148  to the outer surface of body  134 . Slots  152  are circumferentially equally spaced from one another. 
         [0034]    Central chamber  174  converges into a central passage  154  which extends from chamber  174  into the rear portion of body  134 . Six radial passages  156  (only four shown) communicate with and extend radially outwardly from central passage  154  respectively to six axially extending passages  158  which extend forward therefrom to adjacent leading end  136  of body  134 . Passages  158  are circumferentially evenly spaced from one another and each passage  158  is positioned centrally between an adjacent pair of slots  152 . Another set of six radial passages  160  are formed in the cylindrical wall which bounds cavity  144  and extend respectively radially inwardly from passages  158  to cavity  144 . Similarly, a set of six radial passages  166  are formed in the cylindrical portion of pilot tube segment  122  which defines a front portion of interior chamber  173  and extend respectively radially inwardly from the leading ends of passages  172  to interior chamber  174 . Passages  166  thus communicate with annular groove  143  of mounting neck  140 . Pilot tube segments  122  and  125  are connected, to one another by a plurality of bolts  168  extending through holes formed in segment  122  and threadably engaging threaded holes  170  formed in neck  140 . 
         [0035]    Referring to  FIGS. 7 and 9 , steering head  88  is further described. Steering head  88  includes a head portion  188  from which neck  146  extends rearwardly. Portion  180  includes a flat, oval-shaped forward facing steering face  182  ( FIG. 3 ) which angles from a tip  184  on one side of portion  180  rearwardly across to the other side of portion  180 . Like neck  140  of segment  125 , neck  146  defines a pair of axially space annular grooves in which a pair of annular seals  186  are respectively disposed. Another annular groove  188  is formed in the cylindrical outer surface of neck  146  between seals  186  and communicates with passages  160  when steering head  88  is connected to segment  125 . Six radial passages  190  are formed in neck  146  and extend radially inwardly from groove  188  and respectively adjacent passages  160  to a central interior chamber  192  formed in neck  146  and a rear portion of head portion  180 . A central passage  194  extends forward from chamber  192  and then branches into a plurality of exit passages  196  formed in head portion  180 . One of exit passages  196  extends forward to exit opening  90  ( FIG. 3 ) and the remaining passages  196  extend to respective exit openings  192  on the outer surface of head portion  80 . A plurality of bolts  198  extend through holes formed in the front portion of segment  125  and into respective threaded holes in neck  146  of steering head  88  to connect steering head  88  and segment  125  to one another. 
         [0036]    Thus, segments  122  and  125  and steering head  88  are configured with various lubricant passages to allow the flow of lubricant particularly in the form of water to flow from lubricant feed swivel  82  all the way to the outer surface of steering head  88  while allowing target  104  and transmitter  150  to be disposed within pilot tube  84  separate from the flow of the water. The arrows in  FIGS. 5 and 7  indicate the flow of lubricant through the various passages from swivel  82  through pilot tube  48  and steering head  88 . 
         [0037]    The operation of boring machine  10  is now described with reference to  FIGS. 10-14 .  FIGS. 10-13  are shown without main frame  12  of machine  10  for simplicity.  FIG. 10  shows assembly  42  prior to the driving of pilot tube  48  to form a pilot hole with an operator  204  preparing to begin operation of assembly  42 . The pistons of piston cylinder combinations  112  are shown in a fully retracted position  FIG. 10 . Assembly  42  is operated to actuate combinations  112  in order to extend pistons  116  thereof to drive pilot tube  48  into ground  8  as indicated in arrow E in  FIG. 11  to form the initial stages of a pilot hole  206 . During the extension of pistons  116  and pilot tube  48 , camera  100  senses or receives input in the form of light rays from LED target  104  and relays the images of illuminations  180  on the monitor  102 . Operator  204  views display monitor  102  in order to determine the position or orientation of pilot tube  48  and thus whether steering head  88  needs to be adjusted to maintain the line and grade of pilot tube  48 . Operator  204  uses controls  108  in order to make any necessary adjustments, specifically rotating pilot tube  48  as indicated in arrow F in  FIG. 11  via motor  80 . Simultaneously with driving and steering pilot tube  48 , water may be pumped through the lubricant through passages in pilot tube  48  via swivel  82  to steering head  88  and through the exit openings thereof in order to facilitate the formation of pilot hole  206 . At this early stage of pilot hole formation, only one of the standard size pilot tubes  124 A is being used, as shown in  FIGS. 10 and 11 . 
         [0038]    Once the initial driving of tube  48  is performed, pistons  112  are retracted as shown in  FIG. 12  at arrow G and a pilot tube segment  124 B is connected to tube segment  124 A and a rotatable portion of swivel  82  as indicated at arrow H in preparation for additional driving of tube  48 . Drive mechanism  110  is then operated to extend piston  116 , roller assemblies  68  and  70  and pilot tube  48  including segments  124 A and B to lengthen pilot hole  206  as indicated at arrow J in  FIG. 13  while operator  204  provides any rotational adjustment to steering head  88  as indicated at arrow K. The pattern of adding tube segments and continuing to drive pilot tube  48  goes on until the pilot hole is completed or more particularly so that the pilot tube  48  extends out of ground  8  so that sections of pilot tube  48  may be removed as the auger boring operation is underway and thus moves pilot tube  48  gradually forward. 
         [0039]    However, pilot tube  48  may only be controlled by the theodolite control assembly to maintain a proper line and grade thereof for a certain distance, which is typically about 400 feet from camera  100 , as represented by D 1  in  FIG. 14  although camera  100  is not shown in  FIG. 14 . When the distance is too far for camera  100  to sense the illuminations  180  ( FIG. 5 ) of target  104 , the second stage of guidance control of pilot tube  48  comes into play. At this point, transmitter  150  emits an RF signal as indicated at the dotted line in  FIG. 14  which is received by an RF receiver  208  carried by a second operator  218  above ground. Thus, as pilot tube  48  is driven forward as indicated at arrow L in  FIG. 14 , second operator  210  walks along as indicated at arrow M with receiver  208  in order to receive the transmitter signal and thus determine the position of pilot tube  48  at its leading end in order to determine how it should be steered. Operator  210  then communicates the findings to operator  204  by any suitable means of communication or a remote control may be used in order to control motor  80  in rotating pilot tube  48  to keep pilot tube  48  on a proper line and grade during the remainder of driving the pilot tube to complete pilot hole  206 . 
         [0040]    Once pilot hole  206  is completed, assembly  42  is removed from frame  12  of auger boring machine  10  and an auger is then connected to a rotational output shaft powered by engine  24  along with the pipe or casing in which the auger is disposed and cutting head connected to the front of the auger. A swivel is also connected to the trailing end of pilot tube  48  and the front of the cutting head to allow for the rotation of the auger and cutting head independent of rotating pilot tube  48 . The swivel is described in greater detail in the copending application Method of Installing Large Diameter Casing and Swivel For Use Therewith which is incorporated herein by referenced and filed concurrently herewith. 
         [0041]    In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. 
         [0042]    Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.

Summary:
An auger boring machine includes a two-stage guidance control system for controlling a pilot tube during formation of an underground pilot hole which is subsequently followed by an auger to form a larger hole for installation of underground pipe. The system includes a first stage guidance control mechanism for guiding the pilot tube during a first stage of driving the pilot tube and a second stage guidance control mechanism for guiding the pilot tube during a second subsequent stage of driving the pilot tube. The first stage mechanism typically includes a theodolite which allows for pilot tube control during the first several hundred feet of pilot hole formation. The second stage mechanism typically includes a sonar sensor such as a radio frequency receiver for sensing signals transmitted from within the pilot tube and allows for pilot tube control when the first stage mechanism is no longer functional.