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CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to provisional application 62/110,581, filed Feb. 1, 2015. The contents of that application are incorporated fully herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The application relates to fence post removal devices. Removing posts, such as steel posts, may be a physically difficult job that can require multiple persons, and/or may result in physical harm to the person or persons trying to remove the post from the ground. Fence posts may be placed in a variety of locations to demarcate property, lines or to section off property for various uses, such as for farming or horse or livestock pens. 
     Fence posts may conic in a variety of shapes, sizes, and configurations. One particular model of fence post is the T-post. In addition to their generally T-shaped cross-section, T-posts have a row of studs projecting from a flat side of a crossbar. The projections allow for attaching and aligning fencing such as wire fencing. T-posts are designed to have a cross-sectional shape like a letter T. T-posts have become popular because they are relatively low cost and easy to install quickly. 
     In placing fence posts, holes may be dug in the ground in which fence posts are placed with concrete or other foundational materials, or driven into the ground with hammers or other concussive devices. If the posts need to be removed for any reason, a significant amount of force may be required to lift the post from the ground. Ground which may have been tilled or otherwise softened for installation may have hardened. The locations where fence posts are installed may include locations which may become covered in a variety of vegetation and/or habitats for local animals, including spiny or thorned plants and venomous creatures. 
     Such removal can be physically demanding and may lead to exhaustion, muscle fatigue, abrasions, lacerations, and poisonous or benign animal bites. In other words, removal of fence posts may be hazardous for a variety of reasons. Additionally, multiple people may be required to remove each fence post using conventional devices. 
     BRIEF SUMMARY OF THE INVENTION 
     To address problems encountered by persons seeking to remove a fence post, and in particular a T-post, the present application provides a device for removing the fence post from an installed location, whereby the fence post is installed such that at least a portion of the fence is buried under the surface of the ground and may also be within concrete or other foundation material 
     In particular, the present technology relates to a fence post removal device comprising a housing including a first end with a first opening, a second end with a second opening, and central passageway connecting the first opening to the second opening, the central passageway defining a longitudinal axis and the housing being configured to receive a fence post and allow the fence post to emerge at least partially from the second opening, an attachment element attached to the housing and configured to be attached to an external force providing device to transfer a force from the external force providing device through the housing and to the fence post; and a fence post engagement mechanism rotationally attached to the fence post removal device and configured to engage with the fence post, the engagement mechanism being unbiased and rotationally limited to prevent movement beyond a predetermined angle relative to the longitudinal axis; wherein the fence post engagement mechanism is configured to (a) move upwardly as the fence post moves upwardly through the central passageway and (b) drop into a locking arrangement with the fence post due to the fence post engagement mechanism fitting in a complementary manner. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a manual fence post puller. 
         FIG. 2A  illustrates a fence post puller which may be attached to a tractor. 
         FIG. 2B  illustrates the fence post puller according to  FIG. 2A  attached to a tractor. 
         FIG. 3  illustrates a manual fence post puller which may be attached to a tractor. 
         FIG. 4A  illustrates a fence post in the form of a T-post. 
         FIG. 4B  illustrates a cross-section of  FIG. 4A . 
         FIG. 5A  illustrates a fence post puller. 
         FIG. 5B  illustrates the fence post puller of  FIG. 5A  in use. 
         FIG. 5C  illustrates a cross-sectional view of  FIG. 5A  along a longitudinal axis. 
         FIG. 5D  illustrates a cross-sectional view of  FIG. 5A  transverse to the longitudinal axis. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a conventional post removal system  100 . The conventional post removal system includes a base  101  which is placed on the ground near to an installed fence post. Upright  102  projects upwardly perpendicularly to the orientation of base  101 . At the top of upright  102 , a hinge  103  connects upright  102  with crossbar  104 . A first end  105  of crossbar  104  is configured to engage the fence post at its base close to the ground and a second end  106  of crossbar  104  is configured to have a user push downwards thereupon. Due to a lever action around the hinge  103 , the first end lifts upwards and pulls a buried section of the installed fence post out of the ground. 
       FIG. 2A  illustrates a second conventional post removal system  200  which requires the use of a machine  205 , such as a backhoe or tractor. The second system relies upon a housing  201  with an aperture  202  and attachment points  203  to which a flexible connection device  204  may be attached. The connection device  204  must be attached to the machine  205  to operate the system. 
       FIG. 2B  illustrates the second conventional post removal system  200  during operation. The connection device  204  is attached to the machine  205  at a liftable part  206 , like a front scoop on a front loader. The aperture  202  is placed around a standing fence post  207  so that the housing  201  drops around the fence post. The housing is moved forward to engage a protrusion from the fence post  207 . This movement may be done by driving the machine forward or manually. The device  201  is then pulled upward  208  by the machine  205 . The housing is placed manually onto the fence post or placed onto the fence post  207  by moving the machine  205  to drag the housing  201  across the fence post  207  such that the aperture  202  passes over the top of the fence post  207  and drops downward. The machine  205  has to be started and driven forward to engage the device  201  with the fence post  207  in addition to operating the machine&#39;s lifting mechanisms to pull the fence post  207  from the ground. 
       FIG. 3  illustrates a third conventional post removal system  300 . In this system, a hollow rectangular body  301  is includes a ratchet plate  302  that rotates around a crossbar  303 . The ratchet plate  302  includes a weight  304  placed on the ratchet plate  302  to force it downwards. Additionally, system  300  includes a sidebar  305  attached to the ratchet plate  302  and biased downwards by a spring  306 . Sidebar  305  acts as a release device via string  307 . Arms  308  project outwardly and allow attachment to a tractor by a transverse attachment bar  309  connected to a digger boom on the back of the tractor. The body  301  and tractor must be aligned correctly with fence post  310  for the device  300  to engage with projections from the fence post  310 . Being aligned correctly means that the front face  311  of the fence post  310  is arranged parallel to the edge of ratchet plate  302  such that the projections  312  project perpendicular to the edge of the ratchet plate  302 . 
       FIG. 4A  illustrates an exemplary fence post in the form of a T-post  400 . The fence post has a body  401  with a first lateral rib  402  and a second lateral rib  403  projecting opposite to the first lateral rib  402 , the first and second lateral ribs defining a front face  404 . The body  401  also includes a top rib  405  projecting perpendicular to a plane defined by the lateral ribs  402 ,  403  and corresponding to front face  404 . Lateral ribs  402 ,  403 , and top rib  405  run the longitudinal length of body  401 . The body  4011  also includes a number of protrusions  406  projecting periodically in a direction opposite to the top rib  405 . Protrusions  406  are spaced to protrude at a regular distance from each other and are used to help secure wire, either directly or via a fastening mechanism, to the T-post. 
       FIG. 4B  illustrates a cross-section of a T-post. 
       FIGS. 5A-5D  illustrate an exemplary configuration of the present technology. The fence post removal device  500  includes a body  501  with a first end  502  and a second end  503 . The first end  502  has a shroud  504  projecting outward at a predetermined angle. The shroud  504  may be shaped to mirror the shape of the housing  501 . The outward projection of the shroud may be linear or curved. In  FIG. 5A , the housing  501  and shroud  504  are illustrated in an annular arrangement, with the shroud having a greater diameter than the housing. A lid  505  functions as a fence post engagement mechanism and is attached to the second end  503  of the housing via connection  506 . The connection  506  is illustrated as a hinge. The lid  505  optionally may have a handle  512  attached to assist with lifting the lid. The handle may be configured as illustrated or in any way which allows adequate force to be applied to lift the fence post engagement mechanism to disengage from a fence post. The handle  512  may be made from a forged bar with a bend and two ends attached spaced apart on top of the lid  505 . The two ends may be spaced far enough apart that the fence post passes between them as the fence post passes through the device  500 . 
     The device  500  may be attached to a machine  515  like a tractor or front loader via a chain or similar device so the device hangs lively from the machine, as illustrated in  FIG. 5B . Due to the shroud  504 , the device may be lowered over the top of an exposed end of an installed fence post. As long as any part, of shroud  504  is located over the top of the fence post, lowering the device will cause the device to capture the fence post and direct it towards a central passageway  507  going through the body  501 , the central passageway defining a longitudinal axis of the device. The central passageway  507  is best illustrated in  FIG. 5C , which is a longitudinal cross section of the device  500 . 
     As the body  501  of the device is lowered over the fence post, an internal guide  508  may cause the device to move and/or rotate and self-align the device  500  with the top of the fence post. Internal guide  508  may include a conical shape or opposed plates arranged at angles relative to the longitudinal axis of the device. The central passageway  507  may be shaped complementary to the shape a the fence post. In the case of a T-post, the cross-sectional shape of the central passageway may be similar to a lower case “t” as is the cross-sectional shape of a T-post, as illustrated in  FIG. 4B . The combination of the internal guide  508  and the central passageway  507  having a complementary shape allows the device  500  to approach the fence post from a range of angles and still correctly engage the post due to the self-aligning design of the device  500 . 
     Lid  505  is configured to engage the protrusions  511  of the T-post, as best illustrated in  FIG. 5C . As the fence post  510  passes through the body  501  via central passageway  507 , the fence post protrusions  511  pass the lid  505  and allow the lid to lockingly engage the post after a protrusion has passed the lid. The fence post may continue to pass through the body  501  until the top of the fence post abuts a transverse bumper  509  arranged at a distance from the second end  503  of the body. The bumper  509  may be oriented perpendicular to a central passageway  507  passing through the body along the axis of the body. The bumper  509  may be arranged such that the top of the fence post will abut the bumper or such that the top-most protrusion will abut the bumper when the fence post passes through the housing  501 . A stop  514  may be provided to prevent the fence post engagement mechanism  812  from rotating beyond a predetermined angle 
     As best illustrated in  FIG. 5D , the central passageway  507  may be complementary to the shape of the fence post passing though the body  501 .  FIG. 5D  illustrates the housing  501  in cross section across the body transverse to the longitudinal axis of the device. In  FIG. 5D , the fence post is labeled with the same labels as those found in  FIGS. 4A-B  for simplicity. 
     The bumper  509  may be attached to the body  501  offset axially at a predetermined distance D, as seen in  FIG. 5A , from the second end  503  of the body  501 . The bumper may be incorporated into an upright handle  513  as illustrated in  FIGS. 5A-B  or may be a separate device. The upright handle  513  may allow the device to be easily carried and transported. The upright handle  513  may also serve as or incorporate a separate attachment point to which a cable, chain, rope, or other similar device may be attached to allow the device  500  to be suspended from the machine. 
     The bumper may also be arranged at a predetermined distance from the lid  505 , which corresponds to a distance the fence post may project from the second end  503  of the body so that the lid  505  will be arranged between two consecutive protrusions from the fence post when the top of the fence post reaches bumper  509  and the lid is in a closed position. Preferably, the distance will be such that when the fence post has passed through the central passageway and abuts the bumper  509 , the lid  505  will not abut the bottom of a protrusion which has just passed the lid (such that the lid can be opened without striking the protrusion). 
     The bumper  509  is preferably arranged at a distance so that the fence post may pass through the body  501  a sufficient distance to allow the device  500  to capture the fence post and pull it upwards, but not allow the fence post to pass completely through the device  500 , which could result in the device dropping all the way to the ground. Dropping the device all the way to the ground may require the operator to dismount from the machine to retrieve the device from the ground. The bumper  509  preferably ensures that the fence post passes sufficiently through the device while being set at a distance that the fence post engagement mechanism (e.g., lid  505 ) is arranged between consecutive protrusions when the top of the fence post abuts the bumper. Such a bumper arrangement enables release mechanism  512  to lift the lid and release the fence post. The bumper and release mechanism  512 , illustrated as a handle, ensure that the release mechanism may be simple. The release mechanism  512  may alternatively or additionally be a rope, chain, or any other device which lifts the lid  505  after the fence post has been removed from the ground. The release mechanism  512  may be accessible from the machine such that the user may release a removed fence post from a position on the machine  515  without having to dismount to actuate the device  500 . 
     The engagement mechanism (lid  505 ) may also feature an additional and/or separate engagement tool (not illustrated) configured to engage with the fence post as it passes through the body  501 . The engagement tool may engage with a recess in or a projection from a fence such that the engagement mechanism  505  and/or engagement tool and fence post may enter a locked arrangement. The engagement tool may be an edge of the lid  505 . The edge of the lid  505  may lift as the fence post  510  moves upwardly through the body  501  due to a top of a protrusion  513  pushing the bottom of lid  505  as the fence post  510  moves upwards. After the lid  505  is raised a sufficient distance, the angle of the lid  505  allows the lid  505  to slide past the protrusion  511  and drop back down to a position approximately transverse to the longitudinal axis of the body and below the protrusion  511 . 
     With the protrusion  511  above the lid  505 , the machine  515  or other force providing device may lilt upwardly and the protrusion  511  again contacts the lid  505 , but in this situation, the top of the lid  505  abuts the bottom of the protrusion  511 . In this position, the lid  505  abuts the upper end of body  501  at its second end  503 . The upward force provided by the machine  515  causes the fence post  510  to move upwardly with the fence post removal device  500 . 
     Once the fence post has been removed from within the ground and hangs freely from the machine, an operator may then release the fence post  510  from engagement with the removal device  500  without having to get off of the machine. To release the fence post, the operator may utilize a release mechanism  511  provided on the fence post removal device  500 . 
     The engagement mechanism  505  is preferably freely rotatable and/or unbiased with freedom of movement around connection  506 . In the configuration illustrated, the hinge  506  allows the lid  505  to move up and down freely without any additional parts such as springs biasing the engagement mechanism. The device is able to use gravity both to lower the device onto a fence post and to engage the device with the fence post without requiring additional parts or force-providing elements. Without any spring or similar extra biasing mechanism, the lower cost, ease of manufacturing, and improved reliability may be achieved. Similarly, once the fence post has been pulled from the ground, the device advantageously allows a simple mechanism operated remotely to release the fence post from the device, taking advantage again of gravity to separate the device from the removed fence post. 
     While the present technology has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Summary:
A fence post removal device is provided which provides a simple mechanical device to allow a person to remove a fence post from an installed position within the ground. The device allows the person to sit atop a machine like a tractor or front loader, position the device over an exposed end of the fence post, and lower the device such that an internal guide causes the device to self-align with the top of a fence post which passes through the device a specific distance before coming into contact with a bumper which prevents the device from dropping too close to the ground.