Patent Publication Number: US-7713001-B1

Title: Pipe extractor apparatus and method of extracting pipe

Description:
TECHNICAL FIELD 
   This invention relates generally to apparatus and methods for extracting pipe from beneath a ground surface and to a method of extracting underground pipe. 
   BACKGROUND OF THE INVENTION 
   Water, gasoline and oil as well as other fluids are commonly routed through pipe that is buried beneath a ground surface. Thousands of miles of pipe are generally required to reach selected destinations. Over time, the pipe may become obsolete, or placed out of commission for some reason. As a result, it is desirable, and in some states mandatory, that the unused pipe be extracted from beneath the ground surface. The recovered pipe is generally valuable, and may be suitable for reuse, recycled, or used in some other capacity, such as a structural member in construction. 
   The pipe is presently recovered by digging along the pipe line, and thereafter, in a separate operation, removing the pipe. Commonly, a backhoe is used to dig a trench, and another backhoe may follow with an implement having jaws for removing the pipe. In addition, a separate bulldozer is typically used to backfill the trench that was dug to remove the pipe. The present practice for removing pipe is extremely time consuming and laborious, and typically allows one mile of pipe or less to be extracted per day. Additionally, the present process typically creates a wide area of disturbed soil on both sides of the trench, thereby requiring extended amounts of time, effort and labor to backfill the trench. When the pipe line that is being removed is under a farm filed, a substantial area of valuable crop may be damaged during removal of a pipe line employing a conventional tractor backhoe or and excavator. Contamination of the top soil by subsoil may reduce crop production for several years. 
   SUMMARY OF THE INVENTION 
   The pipe extractor, for extracting pipe line from the ground includes a main frame with a left side beam and a right side beam. The left and right side beams are parallel to and laterally spaced from each other. A transverse beam is fixed to the left side beam and the right side beam adjacent to a rear end of the main beam. A left wheel arm with a left arm rear portion and a right wheel arm with a right arm rear portion are provided. An axle is attached to the left arm rear portion, the right arm rear arm portion and the rear end of the main frame. The axle pivotally supports the left wheel arm outboard of the main frame left side beam. The axle pivotally supports the right wheel arm outboard of the main frame right side beam. A left tire and wheel is journaled on a forward end of the left wheel arm. A right tire and wheel is jounaled on a forward end of the right wheel arm. A cross beam is fixed to the left wheel arm and the right wheel arm and spaced from the axle. At least one hydraulic cylinder is connected to the main frame and to the left wheel arm and the right wheel arm and is operable to move the main frame vertically. 
   An extractor assembly includes and extractor frame that is pivotally attached to the main frame for pivotal movement about an extractor pivot axis. A pair of spaced apart shanks have upper shank ends attached to the extractor frame. An extractor shoe with a U-shaped lower wall has a shoe left edge integral with a lower end of one of the pair of spaced apart shanks. A shoe right edge is integral with a lower end of the other one of the pair of spaced apart shanks. The pair of shanks and the extractor shoe provide a through pipe passage. 
   A ramp assembly is pivotally attached to the extractor shoe and extends rearwardly and upwardly from a trailing edge of the extractor shoe. The ramp assembly includes a pair of elongated spaced apart ramp bars that lift pipe passing through the pipe passage upwardly out of the ground. 
   At least one self leveling linkage assembly includes a drive link pivotally attached to the left wheel arm and the right wheel arm. A driven link is pivotally attached to the main frame. The driven link has a rear end pivotally attached to the drive link. A connector link is pivotally attached to a driven link front end and pivotally attached to the extractor frame. The self leveling linkage assembly is operable to pivot the extractor frame about the extractor pivot axis in response to pivotal movement of the left wheel arm and the right wheel arm relative to the main frame. 
   A hitch beam, for towing the main frame has a rear end pivotally attached to the main frame by a hitch pin for pivotal movement about a generally vertical axis. A hitch assembly is mounted on a front hitch beam end. 
   A lock member is mounted on the main frame. The lock member is movable between a released position, in which the main frame is free to pivot about the hitch pin relative to the hitch beam, and an engaged position. In the engaged position, the lock member blocks the main frame from pivotal movement relative to the hitch beam. The extractor shoe cooperates with pipe being extracted to pivot the main frame about the hitch pin relative to the hitch beam when the lock member is in a release position. 
   A front earth working tool is attached to the hitch beam forward of the main frame. The earth working tool is a lister. 
   A deflector plate is secured between the pair of space apart shanks above the through pipe passage. The deflector plate extends rearwardly and upwardly from a horizontal leading edge and lifts soil upward as the soil passes between the space apart shanks. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Some of the objects, features and advantages will be apparent in view of the following detailed description of the presently preferred embodiments and best mode, appended claims, and accompanying drawings, in which: 
       FIG. 1  is a perspective view of the pipe extractor apparatus with parts broken away; 
       FIG. 2  is an enlarged perspective view of the pipe extractor with parts broken away; 
       FIG. 3  is a reduced left side elevational view with parts broken away and the pipe extractor in operation; 
       FIG. 4  is an enlarged side elevational view with parts broken away and the pipe extractor in a transport position; 
       FIG. 5  is an enlarged side elvational view with parts broken away and the pipe extractor in operation; 
       FIG. 6  is an enlarged perspective view of the pipe extractor tool shown removed from the frame; and 
       FIG. 7  is an enlarged perspective view of an end of a ramp section with a receiver passage that receives the tongue of a second ramp section. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now in more detail to the drawings,  FIG. 3  illustrates an apparatus  10  for extracting a generally continuous line of pipe  12  that has been buried beneath a ground surface  14 . The apparatus  10  is generally constructed for attachment to a motorized vehicle, such as a tractor (not shown) for example, allowing the apparatus  10  to be pulled along the line of pipe to extract the pipe  12  from beneath the ground surface  14 . The apparatus  10  has a pair of support members, represented here as tires  18 , arranged for relative movement and engagement with the ground  14 . A front plow  20 , represented here as a lister plow is operable to plow a trench  21  to a predetermined depth to facilitate removing the pipe  12  from beneath the ground. The front plow removes grasses, roots and other plant material above pipe line, that could hinder pipe extraction. An extractor  22  is carried by the apparatus  10  rearward of the front plow  20  and is arranged for movement to a depth below the depth plowed by the front plow  20  to position the extractor  22  at least in part beneath the pipe to facilitate extracting the pipe  12  from beneath the ground surface  14 . As the pipe is removed from beneath the ground surface  14 , it trails behind the extractor  22  and is preferably routed over a rear plow  24 . The rear plow  24  is preferably pulled behind the extractor  22  for movement along the ground surface  14  to backfill the trench  21  plowed by the front plow  20 . Accordingly, the apparatus  10  is able to partially uncover the pipe  12  by plowing trench  21 , extract the pipe from beneath the ground surface  14 , and backfill the trench  21  from which the pipe was removed in a continuous process. As such, the apparatus  10  eliminates the need for multiple pieces of machinery, reduces the manpower required to unearth pipe, and greatly increases the amount of pipe that can be unearthed per day by upwards to ten-fold, or more. 
   The apparatus  10  has a main frame  26  constructed of rigid, durable material, such as tubular steel, by way of example and without limitation. The main frame  26  has a front end  27  and a rear end  28  with a pair of laterally spaced sides  29 ,  30  extending there between. Preferably, a pair of plates, referred to hereafter as an upper plate  32  and a lower plate  34 , extend between the sides  29 ,  30  generally adjacent the front end  27  to define a housing  36 . The upper and lower plates  32 ,  34  have through openings  38  in vertical axial alignment with one another and located generally centrally between the sides  29 , and rearward of the front end  27 . The through openings  38  are sized for receipt of a hitch pin  40  to provide releasable and pivotal attachment of a hitch beam  42  to the main frame  26 . 
   The main frame  26  preferably has a pair of upstanding supports  44 ,  45  extending upwardly from the sides  29 ,  30 . One of the supports  44  is located generally proximate the front end  27 , and is shown in drawing  FIG. 2  positioned rearwardly from the upper and lower plates  32 ,  34 , while the other support  45  is located generally adjacent the rear end  28 . Each of the supports  44 ,  45  has a laterally extending beam  46 ,  47 , respectively, to provide a shelf for stowing components of the apparatus, such as the hitch beam  42  and a plurality of the ramp sections  48 . To facilitate stowing the ramp sections  48  and the hitch beam  42 , each of the supports  44 ,  45  preferably has a pair of upstanding restraint rods  50 , shown in  FIGS. 1 &amp; 2 , spaced laterally from one another to retain the ramp sections and the hitch beam on the laterally extending beams  46  and  47 . It should be recognized that the supports  44 ,  45  are preferably spaced a predetermined distance from one another so that guide beams  48  and the hitch beam  42  span the distance between the supports  44 ,  45  and are adequately supported. Additional restraint rods  50  can be added if desired. In addition, to facilitate stowing the ramp sections  48 , the supports  44 ,  45  and preferably have upwardly standing members or rods  52 , shown here as extending upwardly from opposite ends of the beams  46 ,  47  to prevent the ramp sections  48  from sliding off the beams  46 ,  47  when in there stowed position. 
   The rear support  45  is preferably constructed to facilitate stowing the rear plow  24  when not in use and to facilitate transporting the apparatus  10 . Preferably, a receptacle  54  is attached, such as through a weld joint for example, to the rear support  45 , wherein the receptacle  54  is preferably inclined downwardly from the support  45  and sized for receipt of a tongue  55  pivotally carried by the rear plow  24 . 
   The main frame  26  has a pair of extractor housings  56  defined at least in part by the sides  29 ,  30  of the frame  26  and a pair of flanges  58  spaced laterally inwardly from the sides  29 ,  30 . The flanges  58  are preferably attached, such as through the use of a weld joint, to a support beam  60  extending laterally between the sides  29 ,  30  as shown in  FIGS. 4 and 5 . Each flange  58  has a through opening aligned with an opening in the respective sides  29 ,  30 , wherein the aligned openings are sized for receipt of a pivot pin  62 . To facilitate maintaining the extractor  22  in its stowed position, shown in  FIGS. 1 ,  2  and  4 , the main frame  26  preferably has a pair of laterally spaced uprights  64  arranged for releasable attachment to the extractor  22 . The uprights  64  preferably have through openings for receipt of lock pivot pins  66  to releasably maintain the extractor  22  in its upright stowed position. The lock pins  66  attach the forward ends of tension links  73  and  77  to the uprights  64 . The rear ends of the tension links are attached to the extractor  22 , as shown in  FIG. 2 , by pivot pins  79 . 
   The main frame  26  preferably provides pivotal attachment of a pair of driven links  68  ( FIGS. 2 ,  3  and  4 ). A pair of brackets or housings  70  are preferably welded opposite one another to the sides  29 ,  30  of the frame  26 . The housings  70  each have a pair of laterally spaced flanges  72  having axially aligned through holes. The through holes are sized for receipt of lock pins  74 , wherein the pivot pins extend through openings located generally between opposite ends  69 ,  71  of the driven links  68  to provide pivotal support of the driven links  68  relative to the main frame  26 . 
   As best shown in  FIGS. 3 ,  4  and  5 , the wheels  18  are supported for pivotal movement between raised and lower positions relative to the main frame  26  by a pair of arms  76 . The arms  76  are journaled on a transverse beam  83  for pivotal movement relative to the main frame  26  via an axle  78 . The axle  78  is journaled within laterally spaced and axially aligned bearing housings attached to the rear transverse beam  83 , on the rear end  28  of the main frame  26 , for pivotal movement about a transverse horizontal axis of the axle  78 . The axle  78  is fixed at opposite ends adjacent an end  81  of each arm  76 , such as through a weld joint. It should be recognized that the axle  78  may be otherwise attached to the arms  76 , such as through the use of threaded fasteners, friction fit or pins, for example and without limitation, or that the axle  78  may be supported to rotate relative to the arms  76 . 
   Each arm  76  has another end  82  with a stub shaft or hub support  84  extending laterally outwardly therefrom and being sized for journaled support of the wheels  18  to allow the wheels  18  to rotate freely about the supports  84 . Preferably, the hub supports  84  are arranged so that transporting road tires can be readily interchanged with generally larger off-road tires. As such, the hub supports  84  are preferably laterally spaced so that the road tires conform to government road tire track width regulations. It should be recognized that the road tires are used for transporting the apparatus  10  at increased road or highway speeds, whereas the off-road tires are preferably used while extracting the pipe  12 . 
   Each of the arms  76  have upstanding stubs  86 , shown in  FIGS. 4 and 5 , welded adjacent the ends  81 . A cross beam  88  extending laterally between the upstanding stubs  86  and is welded to the stubs. The cross beam  88  has laterally spaced flanges  90  extending toward the driven links  68  for operable attachment of the cross beam  88  to the driven links  68 . Preferably, each flange  90  is pivotally attached to one of a pair of drive links  92  at one end  93  of each drive link  92  by a pivot pin  95 , while another end  94  of each drive link is pivotally attached to a separate one of the ends  69  of the corresponding driven link  68 . As described in the previous pivotal connections, lock pins  96  are preferably used to facilitate the pivotal connections. 
   Each arm  76  has an upstanding lever arm  98  extending generally perpendicularly to the respective arm  76 . The lever arms  98  are shown here as being joined together by a laterally extending connector  100  to insure that the arms  76  pivot in unison relative to the main frame  26 . A pair of double acting actuators, represented here by way of example and without limitation as hydraulic cylinders  102  actuatable via hydraulic fluid channeled through hydraulic lines shown generally at  103 , in  FIGS. 1 and 2 . The hydraulic cylinders  102  extend between the rear supports  45  of the main frame  26  and the lever arms  98 . The cylinder end of each cylinder  102  is connected to the upstanding support  45  by pins  105 . The rod end of each hydraulic cylinder  102  is connected to the upstanding lever arms  98  through the connector  100  by pins  101 . It should be recognized that the hydraulic lines  103  are preferably arranged for quick connect/disconnect to hydraulic lines on a towing vehicle, or that the actuators may be otherwise actuatable, such as by being electrically powered for movement. The actuators  102  move between a retracted position and an extended position to raise the arms  98  and lower the arms, relative to the main frame  26 . The hydraulic cylinders  102  are preferably double acting. Double acting cylinders  102  can lift the wheels  18  off the ground thereby loading the pipe extract or  22  for better penetration into the soil if needed. As the arms  98  are raised, so too are the wheels  18 , thereby lowering the extractor  22  relative to the ground surface  14 . As the arms  98  are lowered, so too are the wheels  18 , thereby raising the extractor  22  relative to the ground surface  14 . 
   The extractor  22 , as shown in  FIG. 6 , has an extractor frame  104 . The extractor frame  104  includes a front beam  106  that is transverse to the main frame  26  and a rear beam  111  that is spaced from and parallel to the front beam. A left fore and aft beam  112  is fixed to the front beam  106  and the rear beam  111  of the extractor frame. A right fore and aft beam  113  is parallel to the left fore and aft beam  112  and is fixed to the front beam  106  and the rear beam  111 . A left ear  109  is fixed to the left end of the front beam  106 . A right ear  114  is fixed to the right end of the front beam  106 . A bore  115  through the left ear  109  and a bore  110  through the right ear  114  are coaxial with each other and define an extractor front pivot axis  117 . A left tongue  119  is fixed to the left end of the rear beam  111 . A right tongue  121  is fixed to the right end of the rear beam  111 . A bore  123  through the left tongue  119  and a bore  125  through the right tongue  121  are coaxial with each other and an extractor rear pivot axis  127 . The left ear  109  and the right ear  114  are pivotally connected to the main frame  26  and the extractor housing  56  by pivot pins  62 . The left tongue  119  of the extractor frame  104  is connected to the rear end of the tension link  73  by pivot pin  79  and the right tongue  121  of the extractor frame  104  is connected to the rear end of the tension link  77  by a second pivot pin  79 , to hold the pipe extractor  22  in a transport position as shown in  FIGS. 1 ,  2  and  4 . 
   The extractor  22  has a pair of laterally spaced shanks or walls  116  depending from another side of the frame  104 . The shanks  116  extend generally perpendicularly from the extractor frame  104  to a generally U-shaped lower wall, referred to hereafter as a shoe  118 . To facilitate movement of the shoe  118  through the earth as it is extracting the pipe  12 , the walls  116  preferably have tapered leading or cutting edges  120  that are preferably tapered between 15-60 degrees, and more preferably between 30-45 degrees. The tapered edges  120 , aside from assisting in the cutting movement of the extractor  22  through the earth, also assist in compacting the earth laterally outwardly to facilitate extracting the pipe  12 . The shoe  118  has an inner surface  122  defining a through passage  124  that can be sized to extract any diameter pipe, as desired. Generally, the pipes range from 4-16 inches in diameter, though it should be recognized that the shoe  118  can be sized to extract smaller or larger pipes, if desired. 
   The shoe  118  is represented here as having a forward section  126  and a rearward section  128 , with an opening  130  being defined therebetween. To further facilitate movement of the shoe  118  through the earth, the forward section  126  preferably has a tapered leading edge  132  extending upwardly between about 15-60 degrees from a bottom surface  133  rearwardly toward the inner surface  122 . In addition to assisting in the movement through the earth, the tapered leading edge  132  also prevents the pipe  12  from being damaged, such as by being cut or gouged as it is being extracted. The opening  130  prevents the build-up of debris, such as dirt or clay, for example, from occurring between the pipe  12  and the inner surface  122  of the shoe  118  by allowing the debris to pass through the opening  130 . The extractor  22  preferably has a deflector plate  134  extending laterally between the shanks  116  that is spaced a predetermined distance from the inner surface  122  of the shoe  118 . The plate  134  is preferably inclined upwardly toward a trailing edge  136  of the shanks  116  to assist in directing the pipe  12  in the intended direction as it is being extracted, and to restrict the pipe  12  from moving upwardly within the extractor  22 . The deflector plate  134  also loosens soil above the pipe  12  to facilitate lifting the pipe through the soil. 
   The rearward section  128  of the shoe  118  has a tongue  138  fixed to its trailing edge  137 . A ramp section connector  139  is pivotally connected to the tongue  138  by a pivot pin  143 . The tongue  55  on a ramp section  48  is received in a passage  152  in the ramp section connector, so that the ramp sections  48  are pulled by the extractor  22  while extracting the pipe  12 . To maintain the connection between the tongue  138  and the respective ramp section  48 , a pin  140  is preferably used to releasably lock the tongue  55  on a ramp section  48  to the connector  139 . 
   Each ramp section  48  of the ramp assembly  141  includes a left side elongated steel bar  220  and a right side steel bar  222 . These steel bars  220  and  222  are parallel to each other and laterally spaced apart to provide a vertical slot  230  between them. A steel bar  224  is positioned between the two elongated bars  220  and  222  on one end and welded to both elongated steel bars. A portion of the steel bar  224  extends from the end of the elongated bars  220  and  222  to form a tongue  55 . An upper steel plate  226  and a lower steel plate  228  are placed in the slot  230  on the opposite end from the bar  224  that forms the tongue  55  and welded in place. The upper plate  226  is recessed downward in the slot  230  to form a trough  232 . The passage  152  is the proper size to receive the tongue  55  formed by the exposed end of the steel bar  224  and form a substantially rigid connection between two ramp sections  48 . The ramp section connector  139  is the same construction as an end of a ramp section  48  with the passage  152  except for the connection to the tongue  138  by the pivot  143 . Soil and sand are free to pass through the vertical slot  230  except for the short connector section between the ramp sections  48 . The pins  140  that lock two ramp sections  48  are subjected to shear forces and isolated from bending loads. The upper edges of the elongated steel bars  220  and  222  define a channel that tends to guide a pipe  12  as the pipe is lifted from the ground. The last ramp section  48  in the assembly  141  is arranged for attachment to the rear plow  24  so that the rear plow is pulled by the extractor  22  via the ramp assembly  141 . A connector member  240  is pivotally attached to the plow  24  by a pivot pin  242 . A tongue  55  on the connector member  240  is received in the passage  152  of the last ramp section  48  and locked in place by a pin  140 . It should be recognized that the ramp sections  48  can be constructed from solid sections of material, and can be extruded, or otherwise constructed, if desired. 
   The rear plow  24  has a pair of blades  150  converging toward one another from front to back to plow the dirt or spoils plowed by the front plow  20  back into the trench  21  as the rear plow  24  is pulled by the ramp assembly  141 . The blades  150  are preferably attached adjacent their bottom edges  152  to a pair of laterally spaced skids  154 , and at their upper edges  156  to a support beam  158 , such as through weld joints. The skids  154  are arranged generally parallel to one another and have bottom surfaces  160  adapted for sliding movement over the ground surface  14 . The skids  154 , aside from being attached to the blades  150 , are also attached to the support beam  158  via a pair of inclined braces  162 . As shown in a connector member  240  with a tongue  55  is pivotally attached to the support beam  158  to facilitate attachment of the rear plow  24  to the ramp assembly  141 . The rear plow  24  is shown in its operating position in  FIG. 5 . 
   The front plow  20  is preferably carried for vertical movement relative to the hitch beam  42  as shown in  FIGS. 1 and 3 . The front plow  20  is carried by the hitch beam  42  via a panographic linkage assembly  164 . The linkage assembly  164  includes a four bar link arrangement on each side of the hitch beam  42 . The front plow  20  is fixedly attached, such as through a weld joint, for example, to a pair of driven links  166  for conjoint movement with a pair of support links  168  and two pairs of drive links  170  and  182  in response to movement of an actuator, such as a hydraulic cylinder  172 , for example. The actuator  172  is operably attached to the drive links  170  via a generally V-shaped bracket  174  and is moveable between retracted and extended positions to move the front plow  20  between a raised, non-plowing position and a lowered, plowing position, respectively. The actuator  172  is a double acting hydraulic cylinder connected to a tractor hydraulic system by hydraulic lines  173 . The bracket  174  has a pair of legs that diverge to ends that are laterally spaced for fixed attachment to the drive links  170 , such as through a weld joint. The legs converge to an apex  180  for pivotal pin attachment to an end of the actuator  172 . To hold the links  166  in a vertical position a pair of fourth links  182  are pivotally attached to the support and driven links  168 ,  166 . The drive links  170  are parallel to the forth links  182 . 
   The hitch beam  42  has rear end connection to the main frame  26  by a hitch pin  40 . The front end to the hitch beam is adapted to be pivotally connected to a tractor  16 , such as through a universally pivotal tongue  266 . The housing  36  defined between the upper and lower plates  32 ,  34  allows the hitch beam  42  to pivot generally laterally in a pendulum fashion, thereby allowing the mainframe  26  to pivot relative to the hitch beam  42 . This pivotal movement about the hitch pin  40  permits the main frame  26  and thus, the extractor  22  to automatically follow the pipe  12  beneath the ground surface  14 . A forked plate  250  is pivotally attached to the front of the main frame  26  for pivotal movement about a transverse horizontal axis. In the position shown in  FIGS. 1 and 5 , the plate  250  keeps the hitch beam  42  from pivoting about the hitch pin  40  making it possible to tow the pipe extractor to a site for extracting pipe  12  from the ground. Once the pipe extractor  10  is in position to extract pipe, the forked plate  250  is pivoted about a hinge pin  252  from the position shown in  FIG. 5  to the position shown in  FIG. 3 . With the forked plate  250  in the position shown in  FIG. 3 , the main frame  26  is free to pivot about the hitch pin  40  and the extractor  22  can follow the pipe  12  that is to be extracted. 
   To prepare the extractor  22  to extract pipe  12 , the pins  79  are removed from the tension links  73  and  77  to permit the extractor frame  104  to pivot about the frame front pivot axis  117 . Pivotal movement of the extractor frame  104  moves the extractor  22  from a generally horizontal transport and storage position shown in  FIGS. 2 and 4  to a generally vertical working position shown in  FIGS. 3 and 5 . The forward end  71  of the driven link  68  on the left side of the main frame  26  is pivotally connected to a left connector link  260  by a pivot pin  262 . A second end of the left connector link  260  is pivotally connected to the left tongue  119  on the extractor frame  104  by a pivot pin  264 . The forward end  71  of the driven link  68  on the right side of the main frame is pivotally connected to a right connector link  260  by a pivot pin  262 . A second end of the right connector link  260  is pivotally connected to the right tongue  121  on the extractor frame  104  by a pivot pin  264 . 
   The drive links  92 , the driven links  68  and the connector links  260  pivot the extractor frame  104  about the extractor front pivot axis  117  to control the attitude of the U-shaped lower wall  118  of the extractor  22  relative to the direction of forward movement of the extractor. The U-shaped lower wall of the shoe  118  of the extractor  22  is positioned with forward section  126  slightly below the rear extractor section  128  so that movement of the U-shaped lower wall forward in soil exerts a downward force on the U-shaped lower wall of the extractor. Pipe  12  that is to be extracted is not a uniform distance below the ground surface  14 . Generally the ground surface  14  is not as horizontal as the pipe  12  that is to be removed and causes the variable depth. It is therefore necessary to raise and lower the extractor  22  as the depth of the pipe  12  changes. The hitch height of a tractor pulling the pipe extractor  10  is not changed when the depth of pipe changes. The angle of the extractor shoe  118  changes each time the hydraulic cylinders  102  are extended or retracted to raise or lower the extractor  22 . The drive links  92 , which are connected to the arms  76  and wheels  18 , transmit motion through the driven links  68  and the connector links  260  to the extractor frame  104  to maintain the U-shaped shoe  118  in the desired position relative to the direction of forward movement of the extractor  22  during removal of pipe  12 . 
   The pipe  12  that requires removal often has welded joints making the pipe one continuous piece with a uniform outside diameter as shown in  FIG. 3 . However, pipe  12  with joints, as shown in  FIG. 5 , can also be removed. 
   The front plow  20  as shown in the drawing is a lister with a double moldboard that turns up the soil on each side of the furrow that is formed. Depending upon the soil and surface conditions, it may be desirable to employ a modified front plow  20 . A disk coulter could be added to cut through plant material under the ground as well as on the surface for example. It may also be desirable to employ subsoiler shank in place of the lister unit described above. 
   The depth of the U-shaped shoe  118  is controlled using a hydraulic system on the towing tractor to control the flow of hydraulic fluid to and from the hydraulic cylinders  102 . Ideally the extractor  22  will make minimal contact with the pipe  12  that is being extracted. If the extractor shoe is too high or too low, contact with the pipe  12  will increase the power required from the tractor to pull the extractor apparatus  10 . This increased power requirement is difficult to detect when the extractor  22  is only a little too high or a little too low. Even when there is a substantial increase in the load on the towing tractor, the operator can not determine if the increase towing force is due to the U-shaped shoe  118  being too low or too high. The load on the tires and wheels  18  is an indication of the vertical forces exerted on the extractor  22  by the pipe  12 . If the pipe  12  is exerting a downward force on the U-shaped shoe  118 , the tires and wheels  18  will resist the downward load and the hydraulic fluid pressure in the head end of the hydraulic cylinders  102  increases. If the pipe  12  is exerting little or no downward force on the U-shaped shoe  118 , the tires and wheels  18  will be lightly loaded and the hydraulic fluid pressure in the head end of the hydraulic cylinders  102  decreases. The hydraulic pressure in the head end of the hydraulic cylinders  102  can be monitored by a pressure gauge connected to the line  103  that is connected to the head end of the cylinders. The pressure gauge permits the operator to hold the U-shaped shoe  118  up close to the pipe  12  but not exerting a significant lifting force on the pipe. The ramp assembly  141  will exert a lifting force on the pipe  12 . The force on the extractor  22  tends to be relatively constant and will not therefore prevent the employment of hydraulic pressure changes in the head ends of cylinders  102  to indicate the need to raise or lower the extractor  22 . 
   The extractor  22  as described above and shown in drawing  FIG. 6  has two shanks  116 . The two shanks  116  provide strength and lateral stiffness. An extractor  22  can be made with a single shank and a shoe  118  that is secured to the shank. A plurality of replaceable shoes  118  for different diameter pipes  12  can be employed. The single shank  116  makes it somewhat easier to change shoes  118  to fit the pipe that is to be extracted. The shoe  118  steers and guides the main frame  26  by pivoting the extractor  22  about the vertical axis of the hitch pin  40  if the through passage  124  of the shoe  118  is only slightly larger in diameter than the diameter of the pipe  12  that is being extracted. 
   During use of the extractor  10 , a section of the pipe  12 , is exposed through the use of a backhoe, for example, and upon removal of a short piece of the pipe  12 , the extractor  22  is lowered into position by actuating the cylinders  102  extending between the supports  45  and the lever arms  98 . As the cylinders  102  retract, the arms  76  pivot upwardly toward the main frame  26 , thereby causing the tires  18  to rise relative to the main frame  26 . As a result, the extractor  22  is lowered so that the pipe  12  is generally aligned for movement through the through passage  124  of the shoe  118 . As the shoe  118  is lowered into position, a link assembly, including the drive links  92  and driven links  68  and connector links  260 , causes the extractor shoe  118  to remain generally horizontal relative to the ground surface  14  and the pipe  12  throughout the movement of the cylinders  102  between their extended and retracted positions. The forked plate  250  is pivoted to a position in which the hitch beam  42  is disengaged as shown in  FIG. 3 . The extractor  22  is allowed to pivot about the extractor front pivot axis  117  relative to the main frame  26 . Accordingly, the through passage  124  of the shoe  118  remains substantially parallel to the pipe  12  as the extractor  22  is raised and lowered as explained above. The drive links  92 , the driven links  68  and the connector links  260  form a self leveling linkage system. 
   The individual ramp sections  48  are attached to one another, with the leading section being attached to the tongue  138  of the extractor  22 , and the trailing section being attached to the tongue  55  of the rear plow  24 . As such, the rear plow is pulled in use by the ramp assembly  141 , which in turn is pulled by the extractor  22 . 
   The front plow  20  is lowered to its furrow plowing position by actuating the cylinder  172  to move toward its extended position. The depth of the trench  21  created is controlled by limiting the movement of the cylinder  172 . As the cylinder  172  is extended, the front plow  20  is lowered. Desirably, the front plow  20  may be lowered to a depth of about one foot beneath the ground surface  14 . The lister front plow  20  can be replaced by a subsoil shank to loosen soil to a greater depth, if required. Upon reaching the desired depth with the front plow  20 , the apparatus  10  is generally ready to begin extracting the pipe  12  in a continuous extraction process. 
   As the pipe  12  is being extracted, generally at a rate of about 1 mile per hour or more, the pipe  12  passes through the through passage  124  of the extractor  22 , upwardly along the ramp assembly  141  and preferably over the rear plow  24 , then back to the ground surface  14 . As the pipe  12  is traveling over the rear plow  24 , the rear plow is backfilling the trench  21  created by the front plow  20  and the extractor  22 . The extractor  22  is able to automatically follow the pipe  12  as the pipe makes turns beneath the ground surface  14 . This results from the main frame  26  being in pivotal connection with the hitch beam  42 . Preferably, to facilitate the pivotal movement of the main frame relative to the hitch beam  42 , the leading edge  132  of the shoe  118  extends forwardly, such as about one foot for example, of the pivot point provided by the hitch pin  40 . Accordingly, the hitch beam  42  pivots within the housing  36  to allow the shoe  118  to follow the pipe  12 . If the main frame  26  initiates a turn to follow the pipe  12 , the user may readily turn the tractor to follow the path of the pipe  12 . If the user desires the hitch beam  42  to remain in a non-pivotal relation to the main frame  26 , a forked plate  250  pivotally attached to the main frame  26 , may be lowered to capture the hitch beam  42  in a generally aligned orientation relative to the main frame  26  as shown in  FIG. 1 . The forked plate  250  preferably has a pair of arms  254  that extend outwardly to fit closely against opposite sides of the hitch beam  42 . The plate  250  is easily moved into and out of locking engagement with the hitch beam  42  by simply lifting or lowering the lock for pivotal movement relative to the main frame  26 . 
   It should be recognized that upon reading the disclosure herein, one ordinarily skilled in the art of the above subject matter would readily recognize other embodiments than those disclosed herein, with those embodiments being within the scope of the claims that follow.