Patent Publication Number: US-2007110521-A1

Title: Method and apparatus for installing a helical pile

Description:
FIELD OF THE INVENTION  
      This invention relates to a method and an apparatus that may be used to install a helical or screw pile.  
     BACKGROUND OF THE INVENTION  
      Helical or screw piles have been used for decades to help support the foundation of buildings, bridges and other civil engineering structures. Traditionally helical piles were used primarily in areas of weak or wet soil and their application was somewhat limited as their installation was difficult without mechanical assistance. However, more recently helical piles have become considerably more widespread in use due to the advent of high torque motors that are used to rotate the piles and drive them into the ground. The resistence of a helical pile to both upward and carrying loads makes it attractive for use in a wide range of different situations. Today helical or screw piles are commonly used in foundation support for commercial and residential buildings, to help support temporary structures, as a support for street light standards, for the support of oil and gas drilling and pumping equipment, for bank retention, and for a wide variety of anchoring applications.  
      Typically a helical pile is installed through the use of a boom truck having a high torque motor positioned on the end of a boom that may be connected to the upper end of the pile in order to rotate the pile and drive it into the ground. Torque is transferred from the motor to the pile through the use an intermediary coupling that is either physically welded to the end of the pile or fastened thereto through the use of bolts, pins or some other mechanical fastener. While such a structure is effective in transmitting rotational movement from the motor to the pile, it can also require a considerable amount of labour to put into operation on account of the need to weld, bolt, pin or otherwise secure the torque coupling to the end of the pile.  
      In many instances piles of significant length are required, which either necessitates the use of a large boom truck having an extended reach or requires that a number of lengths of shorter piling be welded or fastened together as they are driven into the ground. Where a large boom truck is used to drive a lengthy helical pile, difficulties can arise when trying to maintain the pile in a vertical orientation due to the length of the pile and the weight of the drive motor that is attached to its upper end.  
      The cost of utilizing a trunk having an extruded boom can be significant. Large boom trucks also restrict the ability to work in confined areas. In cases where a pile is to be installed in sections, existing equipment makes it necessary to physically attach (and then later remove) the intermediary drive member, to each length of pile. Attaching, removing and subsequently re-attaching the drive member is both time consuming and costly.  
      There is therefore a need for an improved apparatus for installing a helical or screw pile, particularly where the pile is of significant length.  
     SUMMARY OF THE INVENTION  
      The invention therefore provides a method and an apparatus that may be used to install a helical or screw pile whereby the need for the use of a large boom truck is eliminated or minimized, as is the requirement for physically welding, bolting or pinning an intermediary drive member or torque coupling to the end of the pile in order to connect the pile to the motor of a drive head. The invention provides for a drive mechanism that imparts rotational movement to a pile without appreciable movement or displacement of the drive mechanism in a direction generally parallel to the longitudinal axis of the pile.  
      Accordingly, in one of its aspects the invention provides an apparatus to assist in the installation of a helical pile, the apparatus comprising a drive mechanism operatively connected to a power source, said power source causing said drive mechanism to move in a first direction and then subsequently in a second direction in a reciprocating fashion, said drive mechanism having an engaged and a disengaged configuration, when in said engaged configuration said drive mechanism operatively gripping the exterior surface of said helical pile, when in said disengaged configuration said drive mechanism operatively releasing the exterior surface of said helical pile, movement of said drive mechanism in said first direction placing said drive mechanism in said engaged configuration and causing rotational movement of said helical pile, movement of said drive mechanism in said second direction placing said drive mechanism in said disengaged configuration without rotation of said helical pile.  
      In a further aspect the invention provides a method of installing a helical pile, the method comprising the steps of operatively connecting a drive mechanism having an engaged and a disengaged configuration to a power source, when in said engaged configuration said drive mechanism capable of gripping the exterior surface of the helical pile, when in said disengaged configuration the drive mechanism releasing the exterior surface of the helical pile; with said power source operating said drive mechanism to move said drive mechanism in a first direction that places said drive mechanism in said engaged configuration such that further movement of said drive mechanism in said first direction causes rotational movement of said pile; and, thereafter, causing said power source to move said drive mechanism in a second direction thereby placing said drive mechanism in said disengaged configuration without rotation of said helical pile.  
      The invention also provides an apparatus to assist in the installation of a helical pile, the apparatus comprising a drive mechanism having an engaged and a disengaged configuration, when in said engaged configuration said drive mechanism operatively gripping the exterior surface of said helical pile, when in said disengaged configuration said drive mechanism operatively releasing the exterior surface of said helical pile, wherein movement of said drive mechanism when in said engaged configuration causes rotational movement of said pile, when in said disengaged configuration said drive mechanism moving without rotation of said pile.  
      In another aspect the invention concerns a method of installing a helical pile, the helical pile being of the type having a generally hollow longitudinally orientated bore extending therethrough, the method comprising the steps of (i) with a drive mechanism imparting rotational movement to the pile to cause the pile to be rotated into the ground; and, (ii) extracting at least a portion of any accumulated soil or debris from within the pile&#39;s hollow bore.  
      The invention also provides an apparatus to assist in the installation of a helical pile of the type having a generally hollow longitudinally orientated bore extending therethrough, the apparatus comprising a drive mechanism and a soil extractor, said drive mechanism imparting rotational movement to the pile to cause the pile to be rotated into the ground, said soil extractor operable to extract at least a portion of any accumulated soil or debris from within the pile&#39;s hollow bore.  
      In a further alternate embodiment the invention provides an apparatus to assist in the installation of a helical pile, the apparatus comprising a drive mechanism operatively connected to a power source, said power source causing said drive mechanism to move in a first direction and then subsequently in a second direction in a reciprocating fashion, said drive mechanism operatively connected to the exterior surface of said helical pile such that reciprocal movement of said drive mechanism causes rotational movement of said helical pile without appreciable movement or displacement of said drive mechanism in a direction generally parallel to the longitudinal axis of said pile.  
      In yet as further aspect the invention concerns an apparatus to assist in the installation of a helical pile, the apparatus comprising a drive mechanism operatively connected to a power source and to the exterior surface of said helical pile, said power source causing said drive mechanism to impart rotational movement to said helical pile without appreciable movement or displacement of said drive mechanism in a direction generally parallel to the longitudinal axis of said pile.  
      Further aspects and advantages of the invention will become apparent from the following description taken together with the accompanying drawings.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings which show the preferred embodiments of the present invention in which:  
       FIG. 1  is a side view of a street light standard as it would typically be supported upon a helical pile;  
       FIG. 2  is a side view of an apparatus constructed in accordance with a preferred embodiment of the present invention;  
       FIG. 3  is a front view of the apparatus shown in  FIG. 2 ;  
       FIG. 4  is a plan view along the line  4 - 4  in  FIG. 1  showing a pile guide in accordance with one embodiment of the present invention;  
       FIG. 5  is a plan view along the line  5 - 5  in  FIG. 1  showing a pile drive mechanism in accordance with one embodiment of the present invention;  
       FIG. 6  is a plan view along the line  6 - 6  in  FIG. 1  showing a vertical loading head, in accordance with a preferred embodiment of the present invention;  
       FIG. 7  is a plan view of the vertical loading head shown in  FIG. 6  in an open position;  
       FIG. 8  is a side view of the vertical loading head shown in  FIG. 6 ;  
       FIG. 9  is a partial exploded plan view of the vertical loading head shown in  FIG. 6 ;  
       FIG. 10  is a sectional view taken along the line  10 - 10  in  FIG. 6 ;  
       FIG. 11  is a partial side view of an alternate embodiment of the pile drive mechanism shown in  FIG. 2 ;  
       FIG. 12  is a partial plan view of a third embodiment of the pile drive mechanism shown in  FIG. 2 ;  
       FIG. 13  is a partial plan view of a fourth embodiment of the pile drive mechanism shown in  FIG. 2 ;  
       FIG. 14  is a partial plan view of a fifth embodiment of the pile drive mechanism shown in  FIG. 2 ;  
       FIG. 15  is a side view of an alternate embodiment of the apparatus shown in  FIG. 2 ;  
       FIG. 16  is a partial plan view of an alternate drive mechanism pursuant to one embodiment of the invention; and,  
       FIG. 17  is a sectional view taken along the line  17 - 17  in  FIG. 16 .  
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
      The present invention may be embodied in a number of different forms. However, the specification and drawings that follow describe and disclose only some of the specific forms of the invention and are not intended to limit the scope of the invention as defined in the claims that follow herein.  
      By way of introduction,  FIG. 1  shows a typical street light standard  1  that is anchored to the ground through the use of a helical or screw pile  2 . Most commonly helical pile  2  will be comprised of an elongate, generally hollow, cylindrical body or pipe having at its lower end a helical thread attached thereto such that rotation of the pipe causes the pile to be screwed or augered into the ground.  
       FIGS. 2 and 3  show a preferred embodiment of the present invention as it would typically be connected to a boom truck or vehicle  3 . From a thorough understanding of the invention it will be understood that the apparatus constructed in accordance with the invention described herein may in some instances be attached to a boom truck or other vehicle while other cases it may be self-contained on its own platform or skid, particularly where its use is required in confined areas. For illustration purposes an embodiment of the invention mounted upon a boom truck  3  (as shown in  FIGS. 2 and 3 ) will be described in detail below.  
      According to the invention there is provided an apparatus  4  to assist in the installation of a helical or screw pile  2 . Apparatus  4  is comprised generally of a drive mechanism  5  that is operatively connected to a power source  6 . It is expected that in most instances power source  6  will be comprised of a hydraulic pump capable of providing pressurized hydraulic fluid to the various components of apparatus  4  where required. Alternately, power source  6  could be pneumatic or electrical in nature. In any event, power source  6  is operatively connected to drive mechanism  5  in order to allow for movement of the drive mechanism in a first direction, and then subsequently in a second direction, in a generally reciprocating fashion. In the embodiment of the invention shown in  FIGS. 2 and 3 , the reciprocating movement of drive mechanism  5  is accomplished through the use of a hydraulic or pneumatic cylinder  7 . However, as discussed above, movement may also be achieved through the use of an electric solenoid or through the utilization of a mechanical linkage having a rotary gear or cam drive (not shown) allowing for reciprocal movement of the drive mechanism.  
      As is shown particularly in  FIGS. 2 and 5 , in one embodiment of the invention drive mechanism  5  includes a drive chain  8  that is received about the exterior surface of helical pile  2 . In order for the apparatus to function as intended drive chain  8  must completely encircle the exterior surface of the helical pile. In  FIGS. 2 and 5  chain  8  is shown wrapped around the pile one and one-half times. Drive chain  8  has a first end  9  secured to the reciprocating drive member, which in the case of  FIGS. 2 and 5  is hydraulic cylinder  7 . The second end  10  of drive chain  8  is secured to a tensioning device  11  that may be a spring (as in  FIGS. 2 and 5 ) or, alternatively, any one of a wide variety of other tensioning devices which could include hydraulic or pneumatic cylinders or electric solenoids. The opposite ends of hydraulic cylinder  7  and tension device  11  that are not connected to drive chain  8  are securely fastened to a portion of the frame  12  of apparatus  4  such that retraction of the piston within cylinder  7  causes a tightening of drive chain  8  about the exterior surface of helical pile  2 . At that point drive mechanism  5  is placed in an engaged configuration with the drive chain securely gripping the exterior surface of pile  2 . Once chain  8  is firmly gripped about the exterior surface of pile  2 , further retraction of the piston within cylinder  7  causes movement of the chain in a first direction toward cylinder  7 , and a resulting rotational movement of the helical pile. Rotation of the pile forces it to be driven or screwed into the ground. Depending upon the nature of the auger on the end of the pile, chain  8  may be wrapped in either a clockwise or counterclockwise manner around the pile&#39;s surface, as required to drive the pile in a desired direction. Movement of drive mechanism  5  in this manner may be referred to as a power stroke.  
      Once hydraulic cylinder  7  has reached the end of its movement in its first direction away from pile  2 , the flow of hydraulic fluid may be reversed to allow the piston to be drawn outwardly from the cylinder toward the pile thereby relieving the tension in drive chain  8 . As the tension in the drive chain is relieved, drive mechanism  5  will proceed to a disengaged configuration where chain  8  is released from its gripping contact with the exterior surface of helical pile  2 . The chain will then be pulled or slid in an opposite direction (ie with second end  10  moving away from the pile) through the operation of tensioning device  11 . With the extension of hydraulic cylinder  7  and the movement of drive chain  8 , the operation of tensioning device  11  causes the drive mechanism to return to a disengaged configuration while the drive chain slides loosely around the exterior surface of helical pile  2 . This movement may be referred to as a return stroke and occurs without rotating the pile.  
      It will be appreciated by those skilled in the art that the reciprocal movement of drive mechanism  5  between the power and return strokes described above will cause drive mechanism  5  to repeatedly engage and disengage the exterior surface of the helical pile, effectively causing the pile to be ratchetted into the ground through the application of successive, spaced apart, power strokes. Depending upon the hardness and characteristics of the ground through which helical pile  2  is to be driven, the relative strength of tensioning device  11  may have to be adjusted to prevent slippage of chain  8  about the pile&#39;s surface. Where tensioning member  11  is a spring, the spring may be replaced with a stronger string having a greater spring constant. In addition, a spring tensioner  14  (see  FIG. 11 ) may be used to place the spring in a constant state of tension. Alternatively, where tensioning device  11  is a hydraulic or pneumatic cylinder or an electric solenoid, adjustments may be made to increase the amount of tension that hydraulic cylinder  7  must apply to drive chain  8  before the chain is permitted to move. The portions of the links of drive chain  8  that contact the exterior surface of helical pile  2  may also be fitted with small gripping teeth or coated with an abrasive substance to help enhance the friction between the chain and pile  2  and to prevent slippage during the power stroke. In still a further embodiment drive chain  8  may be wrapped around the exterior of the helical pile a number of times to increase the surface to surface contact between the drive chain and the pile.  
      The drive mechanism described above will permit helical pile  2  to be rotated and screwed into the ground without the need to attach a large high torque motor to the upper end of the pile. Drive mechanism  5  may also be mounted in close proximity to the ground avoiding the need for large boom trucks when driving lengthy piles. It will also be appreciated that drive mechanism  5  does not require the welding or bolting of drive couplings onto the surface of the helical pile, and does not present a hindrance to maintaining the pile in a desired orientation. In one preferred embodiment of the invention hydraulic cylinder  7  and tensioning device  11  are rotatably attached to the frame  12  to allow both devices to be displaced in a generally vertical plane so that they may be tipped in a downward direction as the pile is screwed into the ground during a power stroke. On the return stroke hydraulic cylinder  7  and tensioning device  11  will tend to swing in an upward direction until they are approximately horizontal once again. Accordingly, the described structure allows helical pile  2  to move in a vertical direction as it is rotated without interference from drive mechanism  5 .  
      It should also be noted that each successive power stroke will entail the application of force to a different portion of the exterior surface of helical pile  2  as the pile slowly moves downward into the ground. Any tendency for the walls of the pile to become damaged through contact with chain  8  is therefore minimized. Further, depending upon the speed at which it is desired to turn the pile a single drive mechanism  5  may be utilized (see  FIG. 11 ) or, alternatively, two drive mechanisms may be installed on apparatus  4  as shown in  FIG. 2 . Where two such drive mechanisms are utilized they are preferably synchronized with their power strokes opposite to one another so that while one drive mechanism is undergoing a power stroke the other drive mechanism is undergoing a return stroke. In this manner pile  2  will effectively be continuously rotated.  
      It should be appreciated by those skilled in the art that a variety of other reciprocating drive mechanisms could be utilized in place of the chain drive mechanism described above. Three such alternate embodiments of the invention are shown in  FIGS. 12, 13  and  14 . In each of these Figures drive mechanism  5  includes a pair of jaw members  15  that have an engaged configuration, where they grip the exterior surface of helical pile  2 , and a disengaged configuration where they are released from the exterior surface of the pile. As in the case of drive chain  8 , when jaw members  15  grip the exterior surface of the pile movement of cylinder  7  (i.e., the power stroke) will cause the pile to rotate. Movement of the piston in cylinder  7  in the opposite direction (ie the return stroke) disengages the jaws from the exterior surface of pile  2  allowing the jaws to be rotated back in an opposite direction without rotating the pile.  
      In the embodiments shown in  FIGS. 12 and 13 , drive mechanism  5  preferably includes a tensioner  16  to engage jaw member  15  about surface of pile  2 . Tensioner  16  may be a spring, hydraulic or pneumatic cylinder, or an electrical solenoid. In  FIG. 12  tensioner  16  is shown as comprising a hydraulic cylinder that is used to rotate jaw members  15  about a pin  17  to allow the jaws to either engage or disengage pile  2 . It will be noted that depending upon sequencing of the operation of cylinders  7  and  16  the helical pile may be caused to rotate in either a clockwise or counterclockwise direction.  
       FIG. 13  is a variation of  FIG. 12  wherein the pile is generally square in cross-sectional shape, and wherein jaw members  15  effectively comprise a generally hook-like portion  18  with a rotatable gate  19 . In this embodiment tensioner  16  is preferably a spring  20  that urges gate  19  toward the exterior surface of helical pile  2 . The power stroke occurs when the piston in cylinder  7  is retracted, resulting in a clockwise rotational movement of the pile. During the return stroke the piston is extended outwardly from cylinder  7  and spring  20  will allow gate  19  to effectively ride over the surface of the pile to permit hook-like portion  18  to be rotated in a counterclockwise direction without a corresponding rotation of helical pile  2 .  
      The embodiment of the drive mechanism shown in  FIG. 14  functions in a generally similar fashion to that shown in  FIGS. 12 and 13 , however, through the use of a significantly different structure. In  FIG. 14  jaw members  15  effectively comprise a first jaw portion  21  and a second jaw portion  22 . Second jaw portion  22  is connected at one end to first jaw portion  21  through a pin  23 . The opposite end of second jaw portion  22  is secured to a connecting rod  24  by means of a pin  25 . Connecting rod  24  is attached to the piston of cylinder  7  and provides a means to impart movement to jaw portions  21  and  22 . The end of first jaw portion  21  adjacent to cylinder  7  contains a first leg  26  and a second leg  27 . First leg  26  is fixed to connecting member  24  by way of a bolt or pin  28 . Second leg  27  is loosely fixed to connecting rod  24  by means of pin  29  that is attached to the connecting rod  24  but received through an oversized bore  30  extending through second leg  27 . Situated about the interior of first and second jaw portions  21  and  22  is a series of grippers  31  that are designed to engage and firmly grasp the exterior surface of helical pile  2 .  
      In operation, when the piston of cylinder  7  is retracted the loose connection between pin  29  and bore  30  will effectively cause first jaw portion  21  to rotate about pin  28  driving grippers  31  into the exterior surface of the helical pile until bore  30  prevents any further movement of the jaw members relative to connecting rod  24 . At that point further retraction of the piston into cylinder  7  will effectively result in a rotational force being applied to helical pile  2  through grippers  31 . When the movement of cylinder  7  is reversed, with the piston extracted from the cylinder, first jaw portion  21  will rotate slightly in a counterclockwise direction about pin  28  until further movement of the jaw member relative to connecting rod  24  is halted by engagement of pin  19  with the side of bore  30 . However, the small counterclockwise rotation is sufficient to disengage grippers  31  from the exterior surface of helical pile  2  such that further withdrawal of the piston from cylinder  7  enables the jaw members to be rotated in a counterclockwise direction about the exterior surface of the pile without rotation of the pile itself. In this manner the reciprocal movement of cylinder  7  will effectively be transformed into a clockwise rotational movement of pile  2 . Reversing the relative positions of pins  28  and  29  so that pin  28  is a smaller pin received within a larger diameter bore, will permit the embodiment of drive mechanism  5  shown in  FIG. 14  to effectively drive the pile in a counterclockwise direction.  
      Yet a further embodiment of drive mechanism  5  is shown in  FIGS. 16 and 17 . In this embodiment drive mechanism  5  includes at least two actuating cylinders  58  and  59  having reciprocating pistons  60  and  61 , respectively, that are connected to a drive gear  62 . In the structure that is shown in the enclosed Figures the attachment of pistons  60  and  61  to drive gear  62  is offset by  90  degrees such that alternating reciprocal movement of the pistons will cause rotation of drive gear  62  about a centrally disposed shaft  63 . In a similar fashion to that as described above with respect to the embodiment shown in  FIG. 2 , drive chain  8  is wrapped around the exterior surface of helical pile  2  so that movement of the drive chain is capable of imparting rotational movement to the pile. In the case of the structure shown in  FIGS. 16 and 17  the ends of the drive chain are connected and the chain forms a continuous loop that both encompasses the exterior surface of the pile and engages drive gear  62 . Accordingly, reciprocal and alternating movement of pistons  60  and  61  will cause drive gear  62  to rotate in a continuous fashion, which in turn will impart a continuous rotational movement to helical pile  2 . In order to maintain and/or adjust the tension of drive chain  8  it may be desirable to include a tensioning device (not shown) which may take the form of any one of a wide variety of devices commonly used to maintain tension in a chain.  
      As the helical pile is continuously rotated the drive chain will engage the exterior surface of the pile and be rotated in unison therewith around the pile in a generally helical or screw-like path. As portions of the chain come into contact with the surface of the pile other portions will be released permitting both the pile and the chain to be rotated, while at the same time permitting vertical movement of the pile (in either an upward or downward direction) without appreciable or significant movement or displacement of the drive mechanism in a direction generally parallel to the longitudinal axis of the pile. To help facilitate the relative movement of the chain and the pile, particularly in instances where the pile is rapidly advanced into or out of the ground, drive gear  62  may be inclined relative to the axis of helical pile  2 . It should also be noted that while the embodiment shown in  FIGS. 16 and 17  includes the use of two actuating cylinders, through mechanical modification of the drive structure and the control mechanism operating the drive mechanism, one, two or more cylinders could be utilized.  
      Referring again to  FIGS. 2 and 4 , in one preferred embodiment of the invention apparatus  4  includes at least one pile guide  32  that engages the exterior surface of helical pile  2  to assist in maintaining the pile at a desired degree of inclination. Pile guide  32  is received about the exterior surface of pile  2  and includes a series of rollers  33  spaced apart about the exterior surface of the pile to effectively confine the pile therebetween. Preferably rollers  33  are positioned in a generally vertical configuration such that they do not interfere with the rotational movement of the pile in the event that they come into contact with its exterior surface. In addition, pile guide  32  includes a gate member  34  that may be opened or closed to allow for the pile guide to be received about helical pile  2 . In the embodiment shown in  FIG. 4 , gate  34  is held in place through a pair of pins or bolts  35 . Pile guide  32  is preferably secured to frame  12  of apparatus  4 . In cases where lengthy piles are to be driven, both an upper and a lower pile guide may be utilized. In such instances (see  FIGS. 2 and 3 ) the upper pile guide may be secured to a vertical column portion  36  of frame  12 .  
      Apparatus  4  may further include a soil extractor situated above the end of pile  2 . In  FIGS. 2 and 3  the soil extractor is an auger  37  that is operatively connected to a rotary drive member  38 . Rotary drive member  38  is preferably a hydraulic motor, but may also be pneumatic or electrically operated. The rotary drive member is slidably received upon vertical column  36  enabling it to be moved in a vertical plane to allow for auger  37  to be inserted into and retracted from helical pile  2 . In the embodiment shown, vertical movement of rotary drive member  8  is accomplished through operation of a jack screw  39 , however, it will be understood that many other manners of moving rotary drive member  38  and auger  37  in an upwardly or downwardly direction may be utilized. Such alternate methods include the use of hydraulic cylinders, pneumatic cylinders, electric solenoids, chain drives, and other similar mechanisms.  
      Since helical piles are generally hollow structures with a cylindrical bore extending through them, as they are rotated into the ground their centre cavities tend to become filled or partially filled with soil. Soil within the pile tends to increase the resistance of the pile to rotational movement which has a corresponding increase in the amount of torque required to rotate the pile into or out of the ground. In addition, as soil builds up within the interior of the pile the soil tends to plug the pile&#39;s internal bore such that as the lower end of the pile is rotated further into the ground the surrounding soil can no longer enter the hollow interior of the pile and must be laterally displaced. For small diameter piles in soft formations, displacing the soil at the tip of the pile may not present much difficulty. However, for large diameter piles and in hard soil formations laterally displacing the soil at the tip of the pile can have a very significant impact on the amount of torque required to drive the pile into the ground. The presence of soil or other debris within the internal bore through pile  2  also has little effect on the weight bearing capacity of the pile. Accordingly, through inserting auger  37  into the hollow interior of helical pile  2  at least a portion of any soil or other debris situated within the pile can be removed, effectively reducing the overall weight of the structure and enhancing the ability of the pile to be driven into the ground through providing a space into which additional soil may be displaced as the pile is driven downwardly. The result is that less energy and less torque is required to drive the pile into the ground. In addition, extending the lower end of the auger down to the bottom tip of the pile provides the ability to loosen the soil as the pile is rotated, further reducing the amount of torque required to set the pile.  
      An alternate embodiment of the invention where the soil extractor is a vacuum tube  55  and a vacuum head  56  is shown in  FIG. 15 . In this embodiment, rather than augering soil from within the interior of pile  2  a vacuum tube  55  may be used to remove soil and other debris from the pile. To assist in loosening and extracting the soil inside the pile the vacuum tube  55  may include a water jet  57 . Water expelled through jet  57  not only loosens the soil within the pile but may be used to fluidize the soil making it easier to extract under suction. In addition to auger  37  and vacuum tube  55 , it should be understood that various other means of removing and or loosening the soil within the hollow interior or helical pile  2  may be utilized.  
      In accordance with another one of the preferred embodiments of the invention, apparatus  4  further includes a vertical loading head  40 . As indicated in  FIGS. 2 and 3 , vertical loading head  40  is mounted upon vertical column  36  of frame  12  and is moveable in an axial direction along the length of column  36 , generally parallel to the longitudinal axis of helical pile  2 . Where vertical column  36  is a standard I-beam vertical loading head  40  maybe secured thereto through the use of a pair of plates  41  that form a channel within which the flange portion  42  of column  36  maybe received (see  FIG. 6 ). In this manner the vertical loading head will be secured to vertical column  36 , but at the same time permitted to slide axially along the length of the column. In the embodiment of the invention shown in  FIGS. 2 and 3 , vertical positioning and movement of loading head  40  is accomplished through the use of a cylinder  43  which may be hydraulic, pneumatic or electrically operated. It will, of course, be appreciated that very wide variety of other methods of attaching vertical loading head  40  to column  36  may be used in conjunction with an equally wide variety of methods of positioning and moving the vertical loading head along the length of the column. Other methods of imparting vertical movement to loading head  40  include the use of jack screws, drive belts, drive chains, and various gear drive systems powered by electric, hydraulic or pneumatic motors.  
      Referring to  FIGS. 6 through 10 , vertical head  40  includes generally symmetrical jaws  44  and  45  which having pile engaging members  46  and  47  that are releasably securable about the exterior surface of helical pile  2 . Jaws  44  and  45  are typically secured to a frame  48  of loading head  40 , which in turn is secured to vertical column  36  through the use of plates  41  as described above. A piston  49 , positioned between jaws  44  and  45 , provides the means to open and close the jaws about the exterior surface of the pile. Through operation of piston  49  vertical loading head  40  is provided with an engaged position with pile engaging members  46  and  47  releasably secured about the exterior surface of helical pile  2  (see  FIG. 6 ), and a disengaged position with pile engaging members  46  and  47  free from contract with the exterior surface of the pile (see  FIG. 7 ). When jaws  44  and  45  are in their disengaged position they are preferably separated by distance large enough to allow for the pile to be received between the jaws. The engagement of the jaw members with the surface of the pile permits the application of a vertical or longitudinal (relative to the axis of the pile) force to be applied to the pile. The ability to apply such a longitudinally oriented force can be of assistance in helping to urge the pile downward where the pile is being installed in a clay or hard ground formation. Alternately, a vertically upward directed force can be of use when trying to extract a pile from the ground.  
      While vertical loading head  40  is applying a longitudinally oriented force to the pile it must also permit the pile to freely rotate. To this end, in the embodiment of the invention shown in  FIGS. 6 through 10  pile engaging members  46  and  47  are equipped an internal semi-circular groove  50  into which are received a series of bearing plates  51 . Bearing plates  51  contain grippers  52  on their interior surface that firmly grasp the exterior surface of helical pile  2  when a clamping force is applied to the bearing plates through movement of jaws  44  and  45  to their engaged position. That is, as jaws  44  and  45  are moved toward the exterior surface of helical pile  2 , pile engaging members  46  and  47  will drive bearing plates  51  inwardly toward the pile until grippers  52  firmly engage the pile&#39;s exterior surface. At that point a vertical load (which may be in either the upward or downward direction) applied to loading head  40  will be transmitted directly to the pile through bearing plates  51  and grippers  52 . At the same time, since bearing plates  51  are received within grooves  50  in pile engaging members  46  and  47 , the pile will be free to rotate under the influence of drive mechanism  5 . Grease or various other lubricants may be applied between bearing plate  51  and groove  50  to reduce the frictional contact therebetween. It should also be noted that while bearing plates  51  are shown as generally plate-like elements, a variety of other bearing structures could equally be employed.  
      With a complete and thorough understanding of the preceding description of apparatus  4 , it will be understood that the apparatus presents a means to rotate and to assist in the installation of a helical pile through the use of a drive mechanism that may be mounted close to the ground without the need for large boom trucks or derricks. The apparatus also allows for the rotation of the pile without the use of couplings or drive members that must be welded, bolted or otherwise fixed to the pile. The described apparatus provides a simple, efficient and cost effective manner of rotating the pile and turning it into the ground. Through the use of one or more pile guides  32 , the vertical orientation of the pile can be maintained at virtually any desired angle. The incorporation of vertical loading head  40  into apparatus  4  provides an operator with the ability to apply a vertical load to the pile (in either an upward or downward direction) to assist in either installing or extracting a pile. In situations where hard or wet ground formations are encountered, auger  37  may be operated to extract a portion of the dirt or other debris within the hollow interior of the pile to further aid in its installation or removal.  
      As discussed, apparatus  4  may include one, two or more drive mechanisms that may be operated in unison to increase the amount of rotational force available to be applied to the pile. Alternatively the drive mechanisms may be operated sequentially so that the combined reciprocal movement of each individual drive member results in a constant rotation of the pile. Furthermore, relatively simple adjustments to drive mechanism  5  allows the drive mechanism to rotate the pile in either a clockwise or counterclockwise direction as may be necessary to install or extract a pile. Where the drive mechanism is a chain drive, reversing the direction of pile rotation is as simple as wrapping the chain around the pile in the opposite direction. Where tensioning device  11  is a hydraulic cylinder, a pneumatic cylinder, an electric solenoid or similar device, reversing the direction of pile rotation can be achieved through reversing the stroke on cylinder  7  and device  11 . In the case where the tensioning device is a hydraulic or pneumatic cylinder reversing the operation of the cylinders could be accomplished through the use of reversing values on the cylinder supply and return lines.  
      The described structure also presents the ability to construct a compact device that can easily fit on the back of a truck or that could be independently mounted on a skid having a dedicated power source. The embodiment shown in  FIGS. 2 and 3  represents but one example of a vehicle that may be used for purposes of transporting and operating apparatus  4 . In this instance the apparatus is attached to the end of a boom  53  containing a series of cylinders  54  that can be operated to adjust the positioning of frame  12 , and hence the vertical inclination of helical pile  2 .  
      It is to be understood that what has been described are the preferred embodiments of the invention and that it may be possible to make variations to these embodiments while staying within the broad scope of the invention. Some of these variations have been discussed while others will be readily apparent to those skilled in the art.