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FIELD OF THE INVENTION  
         [0001]    The present invention relates to the field of vibratory devices for driving a post into the ground.  
         BACKGROUND OF THE INVENTION  
         [0002]    It is generally known to employ vibratory means to drive a post, pile and the like, into the ground, and that by adjusting the frequency and/or amplitude of the vibration, penetration into various different ground types can be achieved. It is also generally known to employ a series of vertical blows to a post, as by hammering, to drive the post into the ground. Post-driving devices such as the above have been designed for attachment to a variety of support vehicles, at the front, back or side of the vehicle. Often, the equipment is hydraulically powered using fluid from a source located on the support vehicle.  
           [0003]    Current devices that are used for driving posts into the ground are generally difficult to mount onto and remove from a support vehicle. What is needed is a device that is simple to mount and remove from a support vehicle, so that the support vehicle can be used midstream for other applications during post installation. Many of the devices are also difficult to operate. In particular, aligning the post for insertion, or securing the post to the device before insertion, is complicated, making the entire insertion process complicated and time consuming. What is needed is a machine that is simple and quick to use. Many of the devices are themselves complex, comprising many parts, or many relatively weak pivot points, or pinch points, and therefore are less sturdy than is optimal and relatively difficult fix, should they break down. What is needed is a device that is simple and sturdy, comprising a small number of sturdy components that are easy to repair or replace.  
           [0004]    Many of the devices use hammering to provide vertical downwards force to drive the post into the ground. Hammering creates a significant amount of noise, which is a nuisance particularly to the operator of the device. Additionally, there is some risk to the personal safety of the operator of such hammering devices.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention provides an improved post-driving device for driving posts and the like into the ground. The improved device is simple and sturdy in design. The device of this invention is readily and detachably mounted to a vertically-adjustable support on a support vehicle, and operation of the device to drive a post into the ground is simple and quick. A post is driven into the ground using a combination of vibration and constant, rather than intermittent, downward force.  
           [0006]    In one aspect, this invention is a device for driving a post into the ground comprising:  
           [0007]    A device for driving a post into the ground comprising:  
           [0008]    (a) a mounting assembly for mounting the device onto a support vehicle;  
           [0009]    (b) a mast having a base;  
           [0010]    (c) a vibrator slidably connected to the mast to slide axially thereon;  
           [0011]    (d) a support cup operatively connected to the vibrator and capable of receiving an end of the post; and  
           [0012]    (e) a force applying means operable to apply constant force to the vibrator to urge it towards the base.  
           [0013]    In one embodiment, the vibrator is slidably connected to the mast by means of a sleeve that surrounds the mast, and which is connected to the vibrator.  
           [0014]    In one embodiment the support cup is operatively connected to the vibrator by attaching the support cup to the bottom of the vibrator.  
           [0015]    In one embodiment the means for applying constant downward force is a hydraulic cylinder assembly. The hydraulic cylinder assembly may be located in the mast or alongside the mast.  
           [0016]    In yet another embodiment, the driving assembly is caused to slide axially along the mast by a hydraulic cylinder assembly.  
           [0017]    In another aspect, this invention relates to a method for driving a post into the ground comprising:  
           [0018]    (a) placing a first end of the post onto the surface of the ground at a point where the post will be inserted into the ground;  
           [0019]    (b) inserting a second end of the post into a support cup that is positioned substantially above the point, the support cup:  
           [0020]    (i) comprising an edge sized to extend around the second end of the post, and  
           [0021]    (ii) comprising a top surface that will transmit vibratory and constant downward force onto the second end of the post,  
           [0022]    (c) applying vibratory and constant downward force by means of the top surface to the second end of the post, such that the post is driven into the ground;  
           [0023]    (d) ceasing the application of the vibratory and constant downward force when the post is inserted a selected distance into the ground.  
           [0024]    In one embodiment, the vibratory and constant downward force is applied by the device of the present invention, in any of the embodiments listed above. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]    [0025]FIG. 1 is a perspective view of an embodiment of the device of this invention.  
         [0026]    [0026]FIG. 2 is a perspective view of an embodiment of the device of this invention.  
         [0027]    [0027]FIG. 3 is a perspective view of an embodiment of the support cup useful in this invention.  
         [0028]    [0028]FIG. 4 is a side view of an embodiment of the device of this invention mounted on a support vehicle. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0029]    Reference will now be made to FIGS.  1  to  4 . The post-driving device  10  of this invention comprises a mounting assembly  12 , a mast assembly  14  and a post driving assembly  16 . Mounting assembly  12  comprises a mounting plate  18 , which preferably reversibly attaches to a vertically-adjustable support on a support vehicle. Mast assembly  14  comprises a base  20  and a mast  22 , and supports driving assembly  16 , which is slidably mounted thereon. Driving assembly  16  comprises a vibrator  24  and a support cup  26 , which together drive a post  50  into the ground by the application of vibration and constant vertical downward force.  
         [0030]    As used herein “post” includes a pole, a pile and other like elongate objects of varying size and dimensions that are inserted into the ground. “Post” includes objects of a variety of cross-sections including circular, square, oval, T- or H-shaped, objects made of a variety of materials, including wood, metal and polymers, and objects with a variety of shapes at either end, including rounded, pointed or flat ends.  
         [0031]    Mounting assembly  12  mounts device  10  onto a vertically-adjustable support  46  that is attached to a support vehicle  48 . As used herein “support vehicle” means a truck, tractor, agricultural vehicle or other vehicle that can be used to carry device  10  from one location to another. Vertically-adjustable support  46  can be permanently or reversibly attached to support vehicle  48  and functions in the context of this invention, to lift device  10  off the ground, to enable transport of the device from one site to another. Preferred support vehicles include conventional tractors known to those skilled in the art, such as bulldozers, which have a vertically-adjustable support to which device  10  can be mounted. Particularly preferred is a skid steer tractor, such as a Bobcat™ tractor. As is appreciated, other support vehicles with vertically-adjustable supports can be used, or designed for use, with device  10 . In the embodiment shown in FIGS. 1 and 2, mounting assembly  12  comprises a mounting plate  18  and support tubing  28 . Mounting plate  18  can be a variety of dimensions and can comprise a variety of mounting capabilities, depending upon the size and type of vertically-adjustable support  46  to which it is attached. Mounting plate  18  is preferably reversibly attached to a support vehicle  48 , for example by means of bolts that extend through selected holes in mounting plate  18  to engage cooperating holes in the vertically-adjustable support  46 . In one embodiment, an adaptor  19  is used between mounting plate  18  and vertically-adjustable support  46 , in order to facilitate or enable attachment of the mounting assembly to the vertically-adjustable support.  
         [0032]    In addition to a carrying function, the vertically-adjustable support  46  may be used to adjust the angle at which device  10  contacts the ground surface, to ensure that the post is driven substantially vertically into the ground. In this regard, vertically-adjustable support  46  may comprise at least one additional pivot that will enable the fine-tuning of the vertical position of device  10 . This feature may be useful for example, when the support vehicle is to be used to install posts into the ground on a hill. Vertically-adjustable supports with an additional pivot are known in the art, for example in conventional tractors, such as front-end loaders or backhoes.  
         [0033]    In the embodiment shown in FIGS. 1 and 2, mounting assembly  12  additionally comprises support tubing  28 . Support tubing  28  is connected to both mounting plate  18  and to mast assembly  14 . Support tubing  28  provides support for mounting plate  18  and for the base of mast assembly  14 . In the embodiment shown in FIGS. 1 and 2, support tubing  28  is offset from the center vertical line of mounting plate  18 , to counterbalance the weight of driving apparatus  16 , which is positioned on the opposite side of mast  22 .  
         [0034]    As is apparent, in other embodiments of the device of this invention (not shown), mounting plate  18  may be directly connected to mast assembly  14  without the use of support tubing  28 . Embodiments of this type might be used, for instance, if mounting plate  18  and mast  22  are sufficiently strong so that the additional support provided from support tubing  28  is not needed, or if the driving assembly is mounted on the front face of device  10  (i.e. facing away from the support vehicle).  
         [0035]    Mast assembly  14  comprises base  20  and mast  22 . Base  20  is directed towards the ground, and may rest on the ground, when device  10  is being used. In one embodiment, shown in FIGS. 1 and 2, mast  22  extends substantially normally from a footplate  21 . Footplate  21  functions to provide a flat extended base that supports mast  22  on the surface of ground and that dissipates the downward forces generated when device  10  is in use, thereby preventing substantial penetration of mast  22  into the ground. Footplate may be any of a number of shapes, including square, rectangular, triangular, oblong, and may even have a three-dimensional shape (i.e. it may not be flat). Additionally, footplate  21  may engage the surface of the ground, as by cleats  23  or other such protruding elements, to prevent substantial horizontal movement of mast  22 , when device  10  is in use. Alternatively, base  20  may comprise cleats  23  or other such protruding elements, without a footplate  21  intermediate therebetween.  
         [0036]    Mast  22  interacts with driving assembly  16 . When device  10  is in use, base  20  or footplate  21  rest on the surface of the ground, and mast  22  extends upwards therefrom. Driving assembly  16  slides axially along mast  22 . Accordingly, mast  22  supports driving assembly  16  and directs and controls the vertical movement thereof when device  10  is being used to insert a post into the ground. Mast  22  can have a variety of shapes in cross section, including square, circular, rectangular and triangular, provided that it is otherwise sturdy enough to support driving assembly  16  and direct and control the movement thereof.  
         [0037]    Driving assembly  16  is slidably mounted onto mast  22 . In the embodiment shown in FIGS. 1 and 2 driving assembly  16  has an elongate sleeve  30  that fits snugly about mast  22 , and slides thereon in a telescoping manner. Although shown in this embodiment as covering the entire length of mast  22 , sleeve  30  may be shorter than mast  22 . In this embodiment, mast  22  and sleeve  30  are essentially rectangular or square, in cross section. This feature prevents driving assembly  16  from rotating about mast  22 , which aids in keeping vibrator  24  and hence support cup  26  engaged over the post that is being inserted into the ground. As is apparent, other means of slidably mounting driving assembly  16  onto mast  22  can be used, for example, a tongue and groove type of arrangement. These other means are intended to be included herein.  
         [0038]    In the embodiment shown in FIGS. 1 and 2, driving assembly  16  is mounted to a bracket  40  that is connected to a hanger  38 , which is connected to sleeve  30 . As is apparent, there are other means of connecting driving assembly  16  to sleeve  30 , and these means are intended to be included herein.  
         [0039]    Axial movement of driving assembly  16  along mast  22  is facilitated by means of a hydraulic cylinder assembly  42 . Preferably hydraulic cylinder assembly  42  is mounted inside mast  22  and sleeve  30 , however it may be mounted on the outside of mast  22  and sleeve  30 . Preferably hydraulic cylinder assembly  42  is mounted along the center longitudinal axis of mast  32 .  
         [0040]    The hydraulic cylinder assembly is mounted between the mast assembly and the driving assembly, to move the driving assembly along the mast. In particular, the hydraulic cylinder assembly moves the driving assembly substantially upwards, and forces the driving assembly substantially downwards onto the end of the post, when device  10  is being used. The hydraulic cylinder assembly may be a dual action type, so that it can be used to drive movement in two directions. In particular, one end of the hydraulic cylinder can be fixed releasably or permanently to mast  22 , and the opposite end (i.e. the piston rod) extending from the upper end of the hydraulic cylinder can engage, releasably or permanently, the elongate sleeve  30  which rides along the mast. This-dual action hydraulic cylinder assembly therefore both forces sleeve  30  and hence driving assembly  16  upwards when actuated by hydraulic fluid in one direction, and pulls the driving assembly downwards when actuated by hydraulic fluid in the other direction. Therefore, the downward force is controlled by the operator.  
         [0041]    In this embodiment, the fluid direction to either port on the cylinder is controlled by a directional valve. The directional valve is an electric over hydraulic valve, which is activated by a three-way momentary switch, which is preferably mounted on the support vehicle and accessible to the operator of the vehicle. In this embodiment, the hydraulic cylinder is powered by a slip stream of hydraulic fluid from the flow to vibrator  24 , which fluid is controlled by the directional valve, as described.  
         [0042]    In another embodiment, the hydraulic cylinder assembly may be a single-action type, attached as described above for the dual-action type, but with a spring that forces sleeve  30 , and hence driving assembly  16 , downwards, when the hydraulic pressure in the cylinder is released or abated. As is apparent, other means of moving the driving assembly axially along the mast can be used, such as for example other types of hydraulic means, or a winch/cable mechanism. These other means are intended to be included herein.  
         [0043]    Driving assembly  16  may be mounted on a side of mast  22  or on the front (i.e. away from the support vehicle) of mast  22 . The preferred location of driving assembly  22  is to one side of mast  22 , as shown in FIGS. 1 and 2, because it enables the operator to see the height of the driving assembly when the device is being used.  
         [0044]    Vibrator  24  comprises a housing within which is disposed one or more hydraulic motors that cause rotation of one or more weights that are eccentrically mounted on shafts within the vibrator housing. Rotation of the eccentrically mounted weight(s) causes vibration of the vibrator, which is transferred to the post via a vibrating surface  32  and the support cup  26 . Details of the vibrator are not shown as such units are well known in the art.  
         [0045]    A remotely located hydraulic pump and source of hydraulic fluid, supply hydraulic fluid under pressure via hydraulic lines, to both vibrator  24  and hydraulic cylinder assembly that moves the driving assembly  16  along mast  22 . Preferably the hydraulic pump and source of hydraulic fluid are located on the support vehicle. The hydraulic pump and associated lines and controls are not shown in the drawings, since these are well known in the art.  
         [0046]    Vibrator  24  is operatively connected to vibrating surface  32 , which can be integral to the vibrator itself or which can be attached, releasably or permanently, to vibrator  24 , so that it vibrates therewith. Vibrating surface  32  may be located below vibrator  24 , as shown in FIGS. 1 and 2. These Figures show that in this embodiment, vibrating surface  32  is formed from the bottom of the vibrator housing. However as is apparent, a separate plate may be attached, as by bolting, to the bottom of vibrator  24 , or elsewhere on vibrator  24 , for example to the side or front of, or to the side (or front) of and below or above the vibrator. The location of vibrating surface  32  is not critical, provided that its location will permit the transmission of both vibration and downward force, to the end of a post.  
         [0047]    Support cup  26  is operatively connected to vibrator  24 . Support cup  26  functions to hold, via its edge  34 , the end of the post, and therefore to keep the post in a substantially vertical orientation during its insertion into the ground. Accordingly support cup  26  must be large enough for the end of the post to be insertable therein.  
         [0048]    Edge  34  of support cup  26  also controls the amplitude of vibration. In particular, support cup  26  can be of varying diameters, which will permit different amplitudes of vibration to be applied to the post that is being inserted. For example, if the diameter of the cup is made larger, the amplitude of vibration will be greater, meaning that there is more side-to-side movement of the post, which may or may not be desired, depending upon the type of ground into which the post is being inserted.  
         [0049]    The top surface  36  of support cup  26  transmits both vibrations from vibrator  24  and downwardly directed force from the hydraulic cylinder assembly, to the post that is being inserted into the ground. In the embodiment shown in FIGS. 1 and 2, the top surface  36  is a portion of vibrating surface  32 . As is appreciated, if vibrating surface  32  extended sideways or frontward of vibrator  24 , support cup  26  would extend from underneath the sideways (or frontward)-displaced vibrating surface  32 .  
         [0050]    In another embodiment (not shown), top surface  36  is vibrating surface  32 . In this embodiment support cup  26  is a cylindrical structure that is operatively attached, as by welding or bolting, to vibrator  24 , for example to the side or front of vibrator  24 .  
         [0051]    As shown in the Figures, support cup can be in the shape of a hollow cylinder that is attached to vibrating surface  32  or to vibrator  30 . This is a preferred structure. However as is apparent, support cup  26  could be a structure that functions in an analogous way to that shown in FIGS. 1-3. For example, support cup  26  could be an indentation into vibrating surface  32  or alternatively a ring attached as by posts, to vibrating surface  32 . Structures that function in an analogous way (i.e. they have an edge and a top surface, as described above) to the support cup shown in FIGS. 1-3 are intended to be included herein.  
         [0052]    Preferably, to provide a compact and sturdy design, support cup  26  is positioned underneath vibrator  24 , and the top surface  36  of support cup  26  is formed from a portion of vibrating surface  32 . However as is apparent, support cup  26  could extend from a side or from the front of vibrator  24  (not shown), either as an independent structure, or mounted beneath a vibrating surface  32 . Support cup  26  is preferably circular in cross section, however it could be another shape, such as oval.  
         [0053]    In operation, device  10  of this invention is first detachably mounted onto vertically-adjustable support  46  of support vehicle  38 . The hydraulic connections between the device  10  and the hydraulic pump, preferably located on support vehicle  48 , are then made. Once thus mounted on support vehicle  48 , device  10  can be operated by controls that are accessible to the operator of the support vehicle. Support vehicle  48  is then driven to the location where the setting and driving of post  50  is to be carried out. Device  10 , and more specifically, support cup  26 , is then positioned generally above the site at which post  50  will be inserted into the ground. At this point, device  10  may be lowered so that base  20  engages the ground surface, but it may also remain off of the ground. Hydraulic fluid is then delivered to the hydraulic cylinder assembly to raise driving assembly  16  a sufficient height to allow post  50  to be inserted vertically under support cup  26 . Hydraulic fluid is then delivered to the hydraulic cylinder assembly to lower driving assembly  16  until top surface  36  of support cup  26  contacts the top of the post. The hydraulic cylinder assembly continues to provide downwards force against the post and vibrator  24  is activated. The post is driven into the ground a distance selected by the operator of the device, by continuous downwards force and vibration. Device  10  may comprise markings that are visible to the operator of the device, to assist with determination of when the post is inserted a sufficient distance into the ground. Driving assembly  16  is then lifted upwards to release support cup  26  from the top of post  50 .

Summary:
Disclosed herein is a device for driving a post into the ground that has: a mounting assembly for mounting the device onto a support vehicle; a mast assembly connected to the mounting assembly and a driving assembly slidably connected to the mast to slide axially thereon. The driving assembly has a vibrator and a support cup operatively connected to the vibrator that is capable of receiving an end of the post. The device drives a post into the ground by the application of vibratory and constant downward force onto the post. This invention also discloses a method of driving a post into the ground. The device of this invention is robust, sturdy and easy to use and repair.