Abstract:
A post driver having a dampening device adapted to isolate the hands and arms of the user from shock.

Description:
BACKGROUND OF INVENTION 
     1. Field of Invention 
     The present invention relates to a post driver. More specifically, the present invention relates to a vibration dampening post driver for driving posts into the ground more comfortably and with less risk of injury. 
     2. Background Art 
     Fences have been used to mark territorial boundaries, prevent trespassers from entering a property, and contain livestock. These fences require that hundreds or thousands of posts be driven into the ground at regular or evenly spaced intervals. Historically, fence builders used large hammers to drive posts, though this was backbreaking—and often dangerous—work. 
     There have been some advances in the post driving art area. Cylindrical post driving devices, such as that shown in Hunt, U.S. Pat. No. 2,098,146—including a post tube, which is open only at the bottom of the tube, and handles on both sides of the tube—were invented long ago. In use, these post driving devices were positioned with the open end of the tube over the post, grasped at the handles, and repeatedly driven down so that the closed top end of the tube impacted the top of the post, driving the post into the ground. 
     However, these traditional post driving devices caused a great deal of vibration and tended to be very jarring to the hands and wrist of the user. Users of these post driving devices often experienced pain in their arms and back and typically experienced discomfort in their hands after repeated use. 
     More recent advances in the area included the use of springs located inside and at the top of the post tube, also known as a driver housing, to somewhat dampen the force of the blow received when the posts are driven into the ground, such as that shown in Iddings, U.S. Pat. No. 2,998,087, and Bowers, U.S. Pat. No. 5,097,912. However, these newer post driving devices with springs internal to the post tube are limited in that the size and number of springs utilized is limited, and thus the dampening ability is minimal. While better than traditional post driving devices that have little or no impact dampening abilities, even these newer post driving devices do not contain sufficient impact dampening capabilities for many people who need to drive a large number of posts. Also, the location of the dampening spring is not effective for dampening the forces transferred from the handles to the hands or wrist of the user. 
     Consequently, a need has long been felt for a post driving device with better dampening abilities to better cushion the jarring impact of driving posts into the ground. 
     BRIEF SUMMARY OF THE INVENTION 
     One or more of the embodiments of the present invention provide for an impact dampening post driving device which includes a shaft having an interior cavity extending to a downward facing opining or openings at a distal end of said shaft. Brackets are physically mounted onto the outside of the shaft for attaching the handles to the shaft. The handles are attached to the bracket by a floating mount. The floating mount allows for a dampening device or spring to be positioned between the handle attach points, or mounting flanges, and the brackets. For example, in one embodiment the mounting flange of a handle has an oversized aperture, and the bracket has a similarly sized aperture where the mounting flange is floatingly mounted to the bracket by threading an undersized bolt through the apertures and capturing the bolt with a nut larger than said apertures. A dampening device is then positioned within the floating region between the bracket and mounting flange. In this way, a dampening spring sits between each handle and the shaft, as opposed to the handles being mounted directly to the shaft. 
     The dampening device or dampening spring by definition can be any elastic device or shock absorbing device, such as for example, but not limited to a bushing made of elastomeric material or a coiled spring or any other elastic device that substantially regains its original shape after compression or extension. 
     A user can grasp the handles and lift the device over a post such that the post is aligned with the opening at the bottom of the shaft. The user can then force the shaft down over the post such that the post enters the interior cavity through the downward facing opening and strike the closed top end of the shaft. This creates vibration and shock in the shaft, but the dampening springs between the shaft and the handles greatly reduce the vibration and shock reaching the handles held by the user, thus reducing the force transferred to the hands, arms and wrist of the user. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a better understanding of the present invention, reference may be made to the accompanying drawings in which: 
         FIG. 1  is an elevation view of the post driving device. 
         FIG. 2  is a bottom view of the post driving device shown in  FIG. 1 . 
         FIG. 3  is a magnified view of the top dampening assembly shown in  FIG. 1 . 
         FIG. 4  is a magnified view of the bottom dampening assembly shown in  FIG. 1 . 
         FIG. 5  is an elevation view of an alternative embodiment. 
         FIG. 6  is a bottom view thereof. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A shock-dampening post driving device, according to an embodiment of the present invention, includes a shaft having an axially extending interior cavity that extends to a closed top end of the shaft and to a distal open bottom end of the shaft. The closed top end of the shaft forms a striking surface that is used to strike posts. The shaft also has a first mounting bracket extending from an exterior wall of the shaft. Additionally, an upper mounting flange of a handle is mounted to the first mounting bracket of the shaft by a first floating mount with a first floating region. Further, a first dampening spring is positioned between the upper mounting joint of the handle and the first mounting bracket. This first dampening spring extends into the first floating region, where it dampens vibration between the shaft and the handle. 
     Another embodiment of a shock-dampening post driving device includes a handle mounted to a shaft by a first floating mount having a first floating region, where the first floating mount allows the handle to float or oscillate within said first floating region. Additionally, a first dampening spring is positioned between the handle and the shaft, where the first dampening spring extends into the first floating region, and where the first dampening spring dampens vibration between the shaft and the handle. 
     An embodiment of a shock-dampening post driving method includes striking an object with [a closed top end of] a shaft [while said object is in an axially extending interior cavity of said shaft] and dampening vibration between the shaft and a handle. The handle is floatingly attached to the shaft by a floating mount, and the dampening occurs in a dampening spring positioned in a floating region of the floating mount between said handle and said shaft. 
       FIGS. 1 and 2  illustrate multiple views of a post driving device  100  according to a preferred embodiment of the present invention. As shown in  FIG. 1 , the post driving device  100  includes a cylindrical shaft  110  having a closed top end  112  forming a striking surface  117 , and an axially extending interior cavity  114  extending to a distal open bottom end  116 . The post driving device  100  of  FIG. 1  further includes two handles  120 , two upper dampening assemblies  130 , two lower dampening assemblies  140 , and a level  150 . 
     Each handle  120  is physically connected to an upper dampening assembly  130  and a lower dampening assembly  140 . Both upper dampening assemblies  130  are physically mounted to the cylindrical shaft  110  toward the top end  112  of the cylindrical shaft  110 . Both lower dampening assemblies  140  are physically mounted to the cylindrical shaft  110  toward the bottom end  116  of the cylindrical shaft  110 . The level  150  is physically mounted proximate the top end  112  of the cylindrical shaft  110 . The axially extending interior cavity  114  is inside the cylindrical shaft  110  and extends to the open bottom end  116 . 
     In operation, a post is held vertically on the spot where it is to be driven into the ground. The open bottom end  116  of the cylindrical shaft  110  is then placed over the top end of the post, and the post is allowed to slide up through the open bottom end  116  of the cylindrical shaft  110  into the axially extending interior cavity  114  of the cylindrical shaft  110  until the top of the post comes to rest against the closed top end  112  of the cylindrical shaft  110 . The level  150  in the cylindrical shaft  110  then alerts the user if the post is currently perpendicular to the ground 
     The user of the post driver device  100  grasps the handles  120 , one in each hand, and lifts the post driver device  100 . Once the post driver device  100  has been sufficiently lifted, the user quickly forces the post driver device  100  downward onto the post, such that the post again slides up through the open bottom end  116  of the cylindrical shaft  110  into the axially extending interior cavity  114  of the cylindrical shaft  110  until the closed top end  112  of the cylindrical shaft  110 , which acts as a striking surface, forcefully impacts the top of the post, driving the post into the ground. This impact creates a great deal of vibration and shock in the cylindrical shaft  110  that is transferred to the handles  120 . The upper damper assemblies  130  and the lower damper assemblies  140  dampen the vibration generated in the cylindrical shaft  110  before the shock and vibration reach the hands and body of the user. The previous post driver designs, which have the handles rigidly mounted to the cylindrical shaft, does not dampen the force transferred to the hands of the user, and the post drivers having the interior springs are not very effective because they only require the user to drive downward with a greater velocity and more force in order to drive a post. 
     The cylindrical shaft  110  may alternatively have a non-circular cross-section, such as a triangular, rectangular, or pentagonal cross-section, or any other shaped cross-section. The cylindrical shaft  110  may be made of a metal or metal alloy, or other material conducive to repeated impacts. The level  150  may alternatively be mounted anywhere on the post driving device  100 , and more levels may be added to give information on more than just one axis. The closed top end  112  of the cylindrical shaft  110  may have some sort of a weight or durable substance with which to exert even more force on a post being driven into the ground. The post driver device  100  may be used to drive things other than posts in directions other than down into surfaces other than the ground. There may alternatively be more or less than two handles  120 , and more or less than two upper damper assemblies  130  and two lower damper assemblies  140 . Further, handles  120  may alternatively be mounted to more or less than two dampener assemblies  130 ,  140 , though never less than one. 
       FIG. 3  shows a magnified view of the upper damper assembly  130  according to an embodiment of the present invention. As shown in  FIG. 3 , the upper damper assembly  130  includes a first mounting bracket  131 , a first damper  132 , a first bolt  133 , a first nut  134 , a third mounting bracket  135 , and a handle  120  having an upper mounting flange  125  at one end. 
     The first mounting bracket  131  and the third mounting bracket  135  are affixed to the cylindrical shaft  110 . Between the two mounting brackets  131 ,  135  are, from bottom to top, the first damper  132 , the upper mounting flange  125  of a handle  120 , and the first nut  134 . The first bolt  133  is inserted through an aperture of the first mounting bracket  131  up through an aperture in the first damper  132  and an aperture in the upper mounting flange  125  of a handle  120 , and is secured in place by the first nut  134 . A portion of the first bolt  133  extends through the first nut  134  and up through an aperture in the third mounting bracket  135 . This creates a floating mount between the upper mounting flange  125  of the handle and the brackets  131 ,  135  attached to the cylindrical shaft  110 . 
     In operation, the first bolt  133  and first nut  134  hold the components of the upper damper assembly  130  in place. The third mounting bracket  135  and first mounting bracket  131  connect the upper damper assembly  130  to the cylindrical shaft  110 . The first bolt  133  connects the first damper  132  and the upper mounting flange  125  (and thus the handle  120 ) to the third mounting bracket  135  and the first mounting bracket  131 , while the first nut  134  secures the first bolt  133  in place. The positioning of the components allows the upper mounting flange  125  (and thus the handle  120 ) to oscillate or float along the first bolt  133  and compress the first damper  132  when the closed top end  112  of the cylindrical shaft  110  is brought down and strikes an object. This dissipates much of the vibration and shock before it can travel from the cylindrical housing  110  to the handles  120 . The first damper  132  then rebounds, pushing the upper mounting flange  125  (and thus the handle  120 ) back to its original position, completing one oscillation. In other words, the floating mount created by this assembly allows the upper mounting flange  125  of the handle  120  to oscillate or float up and down along a floating region  137  in which the damper  132  is installed. 
     In the alternative, things other than the first bolt  133  and first nut  134  may be used to hold the components of the upper assembly  130  in place in a floating relationship, such as adhesive, rivets, welding or other bonding techniques. The first damper  132  may take the form of dense foam or other elastomeric material or shock absorbing material, or may alternatively be a dampening spring or other mechanical shock absorbing device such as a pneumatic or hydraulic shock absorber. The order of the components in the upper damper assembly  130  may change, such as the position of the first nut  134  moving from under to over the third mounting bracket  135  or any similar change. The first damper  132  size and dampening ability may vary according to the needs of the user. 
       FIG. 4  shows a magnified view of the lower damper assembly  140  according to an embodiment of the present invention. As shown in  FIG. 4 , the lower damper assembly  140  includes a second mounting bracket  141 , a second damper  142 , a second bolt  143 , a second nut  144 , and a handle  120  having a lower mounting flange  127  at one end. 
     The second mounting bracket  141  is connected to the cylindrical shaft  110 . Above the second mounting bracket  141  is, from bottom to top, the second damper  142 , and the lower mounting flange  127  of the handle  120 . The second bolt  143  is inserted down through an aperture in the lower mounting flange  127 , through an aperture in the second damper  142  and an aperture in the second mounting bracket  141 , and is secured in place by the second nut  144  below the second mounting bracket  141  to a portion of the second bolt  143  extending through an aperture in the second mounting bracket  141 . This creates a floating mount between the lower mounting flange  127  of the handle  120  and the second mounting bracket  141  attached to the cylindrical shaft  110 . 
     In operation, the second bolt  143  and second nut  144  hold the components of the lower damper assembly  140  in place. The second mounting bracket  141  connects the lower damper assembly  140  to the cylindrical shaft  110 . The second bolt  143  connects the second damper  142  and the lower mounting flange  127  of the handle  120  to the second bracket  141 , while the second nut  144  secures the second bolt  143  in place. The positioning of the components allows the lower mounting flange  127  (and thus the handle  120 ) to oscillate or float along the second bolt  143  and compress the second damper  142  when the closed top end  112  of the cylindrical shaft  110  is brought down and strikes an object. This dampens much of the vibration and shock before it can travel from the cylindrical housing  110  to the handles  120 . The second damper  142  then rebounds, pushing the lower mounting flange  127  (and thus the handle  120 ) back to its original position, completing one oscillation. In other words, the floating mount created by this assembly allows the lower mounting flange  127  of the handle  120  to oscillate or float up and down along a floating region  147  in which the damper  132  is installed. 
     In the alternative, things other than the second bolt  143  and second nut  144  may be used to hold the components of the lower assembly  140  in place, such as adhesive, rivets, welding or other bonding techniques. The second damper  142  may take the form of dense foam or elastomeric material or shock absorbing material, or may alternatively be a dampening spring or other mechanical shock absorbing device such as a hydraulic or pneumatic shock absorber. The order of the components in the lower damper  140  assembly may change, such as the orientation of the second bolt  144  being flipped  180  degrees such that it is inserted from the top down as opposed to from the bottom up, or any similar change. 
       FIGS. 5 and 6  illustrate multiple views of a post driving device  500  according to a preferred embodiment of the present invention. As shown in  FIG. 5 , the post driving device  500  includes a cylindrical shaft  510  having a closed top end  512  forming a striking surface  517 , and an axially extending interior cavity  514  extending to a distal open bottom end  516 . The post driving device  500  of  FIG. 5  further includes two handles  520 , two upper dampening assemblies  530 , two lower dampening assemblies  540 , and a level  550 . 
     Each handle  520  is physically connected to an upper dampening assembly  530  and a lower dampening assembly  540 . Both upper dampening assemblies  530  are physically mounted to the cylindrical shaft  510  toward the top end  512  of the cylindrical shaft  510 . Both lower dampening assemblies  540  are physically mounted to the cylindrical shaft  510  toward the bottom end  516  of the cylindrical shaft  510 . The level  550  is physically mounted proximate the top end  512  of the cylindrical shaft  510 . The axially extending interior cavity  514  is inside the cylindrical shaft  510  and extends to the open bottom end  516 . 
     In operation, a post is held vertically on the spot where it is to be driven into the ground. The open bottom end  516  of the cylindrical shaft  510  is then placed over the top end of the post, and the post is allowed to slide up through the open bottom end  516  of the cylindrical shaft  510  into the axially extending interior cavity  514  of the cylindrical shaft  510  until the top of the post comes to rest against the closed top end  512  of the cylindrical shaft  510 . The level  550  in the cylindrical shaft  510  then alerts the user if the post is currently perpendicular to the ground 
     The user of the post driver device  500  grasps the handles  520 , one in each hand, and lifts the post driver device  500 . Once the post driver device  500  has been sufficiently lifted, the user quickly forces the post driver device  500  downward onto the post, such that the post again slides up through the open bottom end  516  of the cylindrical shaft  510  into the axially extending interior cavity  514  of the cylindrical shaft  510  until the closed top end  512  of the cylindrical shaft  510 , which acts as a striking surface, forcefully impacts the top of the post, driving the post into the ground. This impact creates a great deal of vibration and shock in the cylindrical shaft  510  that is transferred to the handles  520 . The upper damper assemblies  530  and the lower damper assemblies  540  dampen the vibration generated in the cylindrical shaft  510  before the shock and vibration reach the hands and body of the user. The previous post driver designs, which have the handles rigidly mounted to the cylindrical shaft, does not dampen the force transferred to the hands of the user, and the post drivers having the interior springs are not very effective because they only require the user to drive downward with a greater velocity and more force in order to drive a post. 
     The cylindrical shaft  510  may alternatively have a non-circular cross-section, such as a triangular, rectangular, or pentagonal cross-section, or any other shaped cross-section. The cylindrical shaft  510  may be made of a metal or metal alloy, or other material conducive to repeated impacts. The level  550  may alternatively be mounted anywhere on the post driving device  500 , and more levels may be added to give information on more than just one axis. The closed top end  512  of the cylindrical shaft  510  may have some sort of a weight or durable substance with which to exert even more force on a post being driven into the ground. The post driver device  500  may be used to drive things other than posts in directions other than down into surfaces other than the ground. There may alternatively be more or less than two handles  520 , and more or less than two upper damper assemblies  530  and two lower damper assemblies  540 . Further, handles  520  may alternatively be mounted to more or less than two dampener assemblies  530 ,  540 , though never less than one. The handle can include a dampening device system  550  and  551  and gripper handle  552  in addition to the damper assembly  130  described above or in lieu of damper assembly  130 . 
     One or more embodiments of the present invention dissipate the vibration and shock that are created by driving posts into the ground more readily than current post drivers through the use of more and bigger and better dampers mounted directly between the handles and cylindrical shaft of the device. This increased shock absorption decreases the strain on the user of the device, which lessens the likelihood of injury and allows users to use the device for longer periods of time.\ 
     While particular elements, embodiments, and applications of the present invention have been shown and described, it is understood that the invention is not limited thereto because modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. It is therefore contemplated by the appended claims to cover such modifications and incorporate those features which come within the spirit and scope of the invention.