Abstract:
The present invention provides an apparatus that lifts, secures, splits and/or crushes tree stumps or other materials, particularly wooden materials and other materials that may be present at an excavation site. The apparatus is characterized in part by a two pivot point design. A first pivot point allows for the pivotable operation of an engaging unit which grabs and lifts the tree stump. The engaging unit further acts a durable and secure support member for the tree stump during the splitting and crushing process. The second pivot point allows for the pivotable operation of a cutting device which facilitates splitting and crushing of the stumps.

Description:
This application is a continuation of PCT/US00/03940, filed Feb. 16, 2000, which is a continuation-in-part of application Ser. No. 09/251,601, filed Feb. 16, 1999, now U.S. Pat. No. 6,076,572. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus for lifting, excavating, splitting and/or crushing tree stumps, or other materials. The apparatus is characterized in part by a two pivot point design. 
     2. Background 
     A number of mechanical devices have been developed for the crushing and demolition of a variety of materials, including wood. Certain of these devices utilize a frame having an upper and lower jaw for gripping and cutting the material or work product. 
     For example, U.S. Pat. No. 5,533,682 describes a device for crushing and/or cutting concrete, cutting iron sections and/or scrap iron, and cutting and splitting wood. The device comprises a frame having a first jaw that is stationary with respect to the frame, and a second jaw that is pivotable by means of a setting cylinder. While the fixed first jaw is intended to support the material being cut, the pivotable jaw includes a pointed crusher tooth and knife-like section that facilitate the cutting of the material. 
     This device offered some advantages over the art. For example, the jaws of the device were detachably connected to the frame, so that a different set of jaws could be used for different materials being cut. Thus, one device could be used for multiple purposes, as long as one purchased the appropriate sets of jaws. 
     However, this type of device presented certain limitations as a wood splitter and crusher. The particular embodiment described as being suited for cutting and splitting wood employed two serrated strips located on the inner surface of the fixed jaw to prevent slippage of the wood during the cutting process. While this design may be effective for cutting smaller sections of wood, logs, root ends and the like, when cutting larger sections of wood, e.g., tree stumps, forward slippage of the wood becomes highly problematic. Further, the force of the pivotable jaw upon the stationary jaw could lead to dislodgement or misalignment of one or more of the jaws with respect to the frame. 
     A similar device intended for use in the demolition of iron or steel reinforced concrete structures is disclosed in U.S. Pat. No. 5,146,683. This device, termed a reinforcement cutter, also employs a moveable upper jaw and a stationary lower jaw configuration. The device further includes a first and second shearing cutter means that are dismountably secured to each of the opposed inner lateral surfaces of the upper and lower jaws in a bent formation. As in the case above, however, the potential for forward slippage of the wood and/or dislodgement of one or more of the jaws is problematic when using this device for cutting and splitting large sections of wood. 
     Other devices for splitting and crushing tree stumps have been developed that utilize a bit/counter bit configuration. 
     Swedish patent publication 378,502 describes a splitting bit that is pressed between two counter bits. The counter bits are disposed at the adjacent upper edges of arm-like structures that support the tree stump, and have an arcuate shape that facilitates the holding of the stump. 
     However, this configuration has several disadvantages. For example, the area or slit between the counter bits tends to get clogged with debris from the splitting and crushing procedure, particularly at the base section of the slit. This clogging requires that the apparatus be shut down and the slit cleared from time to time during the splitting and crushing procedure. It is also possible that rocks coming up with stump roots may penetrate or lodge in the slit between the counter bits thereby causing damage to the counter bits. Additionally, the arcuate design of the bits can be problematic when replacing dulled bits. Further, unless the pivotable bit is manufactured such that it aligns precisely with the slit between the counter bits, damage to the apparatus is very possible. 
     U.S. Pat. No. 5,080,151 to Pallari describes a tree stump lifting and crushing apparatus comprising one or more lifting hooks and a bit which is pivotable and turnable against a counter bit for crushing tree stumps placed therebetween. The pivotably closable bit and counter bit include a cutting surface and a counter surface. The counter surface is substantially continuous and extends across the width of the cutting surface upon closing of the bits. A closure stop means is provided that is intended to prevent destructive engagement of the cutter surface and counter surface. 
     Though somewhat of an improvement over the prior art, serious problems were encountered by this apparatus. For example, effectively securing the tree stump during the lifting and crushing procedure remained problematic. Additionally, the area or slit existing between the stump hooks invited the same debris and clogging as the devices of the prior art. Consequently, similar limitations were observed in terms of down-time and potential for damage to the apparatus. 
     Another device is described in U.S. Pat. No. 5,636,802 to Tagawa. That device comprises a pair of arms which are substantially identical in configuration and which are rotatably supported attached to a support structure. The Tagawa device is not capable of dual pivot movement due to a limitation in its configuration. Specifically, an arm drive mechanism simultaneously actuates rear ends of the paired arms, thus functioning similar to a single pivot device. Further, the Tagawa device is specifically constructed for demolition of concrete and other structures, e.g., wooden houses. In practical terms, such structures have reduced thicknesses of about one foot. Such a configuration is ill suited for other work products having greater thicknesses, such as tree stumps and the like. Notable disadvantages of using the Tagawa device on such work products include forward slippage and limited power (force) when the arms are in an open position during the crushing operation. 
     There remains a need for an apparatus to securely lift, excavate, split and crush tree stumps that avoids the various problems of the prior art. Specifically, it would be highly desirable to develop a tree stump lifting and crushing apparatus that would offer an increased holding area for the grabbing and subsequent handling of the tree stump during the cutting process. It also would be highly desirable to develop a tree stump lifting and crushing device that could securely hold the tree stump during the cutting process such that forward slippage of the stump would be prevented. It also would be highly desirable to develop a tree stump lifting and crushing device that would avoid the inherent limitations associated with the devices of the prior art that have a stationary jaw configuration. It also would be highly desirable if such a device could offer maximum power in an open configuration for more effective crushing. Further, it would be highly desirable to develop a tree stump lifting and crushing device that would avoid the debris and clogging problems seen in the devices of the prior art. 
     SUMMARY OF THE INVENTION 
     The present invention provides an apparatus that can lift, excavate, secure, split and/or crush tree stumps, as well as other materials, particularly other wooden materials. The apparatus is characterized in part by a two pivot point design. In a preferred design, a first pivot point assembly allows for the pivotable operation of an engaging unit which can grab and lift the tree stump. A second pivot point assembly allows for the pivotable operation of a cutting device which facilitates splitting and crushing of the stump. 
     The novel design of the present invention provides significant advantages over the devices of the prior art utilizing a single pivot point system. For example, the multiple pivot design of the present invention permits a significantly increased holding area for the tree stump or other object during the excavating and crushing process. Additionally, this increased holding area provides better mechanical advantages in general, as the engaging unit and cutting device can be retracted to open wider to accommodate larger tree stumps. This larger, wider opening is particularly useful when grabbing the tree stump at the outset of the excavation process. Further, the novel configuration of the present invention provides a crushing device which offers maximum power when the engaging unit and cutting or grappling devices are in an open position. 
     In preferred designs, the engaging unit and cutting or grappling devices are independently, pivotably and opposedly connected to a lower end of an arm-like supporting structure. An upper end of the supporting structure is attached to a hydraulically powered, manipulatable boom such as a bucket arm of a digging machine, crane or the like. 
     The supporting structure suitably comprises two reinforcing side plates, sometimes referred to herein as “sticks”, with a stick backplate disposed therebetween. The supporting structure has a wider diameter at its lower end. This design provides additional reinforcement to the supporting structure during the splitting and crushing process and avoids destructive engagement of the engaging unit and cutting device. 
     In a preferred embodiment, a plurality of anchor hooks protrude from each of the outer surfaces of the reinforcing side plates of the supporting structure. The anchor hooks provide a means of securing a first and second reinforcing member on either side of the two reinforcing side plates. Typically, one end of the reinforcing member is mounted to the anchor hooks; the other end is secured below, at the pivot point assemblies. This novel aspect of the present invention provides additional support, strength and durability to the apparatus during the tree lifting and crushing operation. Further, this design provides significant ease of operation in terms of mounting and dismounting attachments relative to an excavator. 
     In an alternate preferred embodiment, the reinforcing members are secured to the supporting structure using a plurality of clamps. 
     The engaging unit preferably comprises two side plates and a backplate securely disposed therebetween. In a preferred embodiment, each side plate has a spear-like extension which protrudes from a leading edge of the side plate to facilitate grasping and/or securing of the tree stump during the lifting and crushing process. The planar design of the engaging unit&#39;s backplate does not invite any clogging or debris from the stumps being cut. Therefore, opportunity for damage to the apparatus associated with clogging or debris and downtime associated therewith are substantially eliminated. 
     In an alternate preferred embodiment, the engaging unit may further comprise an attachment, e.g., a rake or a blade. Using such a configuration, the engaging unit can perform an additional function without disrupting the excavating and cutting operation. 
     The cutting device preferably has a curved, sharpened outer surface referred to herein as a knife blade. In a preferred embodiment, a similarly curved, elongated knife tooth is mountably attached to the knife blade. A knife tooth plate is disposed between the two sides of the knife tooth and provides reinforcement and strength to the cutting device structure during operation. The knife tooth and knife tooth plate may be removed, sharpened and replaced as necessary. In an alternate aspect of the invention, a grappling unit is used in place of a cutting unit. In a particularly preferred aspect, a grappling unit may be removably attached to the cutting unit whereby a single apparatus can be readily outfitted for splitting/crushing objects (with use of the cutting unit) as well as lifting and transporting objects (with use of the removable grappling unit). 
     On one side of the supporting structure, a first hydraulic cylinder connects the reinforcing member to a rear portion of the engaging unit. On the other side of the arm-like supporting structure, a second hydraulic cylinder connects the reinforcing member to a rear portion of the cutting device. Using hydraulics controlled from the cab of the digging machine, the two hydraulic cylinders are retracted to facilitate movement and communication of the engaging unit and cutting device during the tree lifting and crushing process. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the tree stump lifting and crushing apparatus of the present invention. 
     FIGS. 2A-2C are sectional views of the engaging unit shown in FIG. 1; FIG. 2D shows an alternate embodiment of the engaging unit which further comprises a rake attachment; and FIG. 2E shows yet an alternate embodiment of the engaging unit which further comprises a blade attachment. 
     FIG. 3 is a sectional view of the cutting device shown in FIG.  1 . 
     FIGS. 4A-4B illustrate two preferred embodiments of the arm-like supporting structure. 
     FIG. 5 is a side view of a preferred embodiment of the present invention. 
     FIG. 6 is a perspective view of an alternate embodiment of the present invention which utilizes a grappling unit. 
     FIG. 7 is a partially assembled view of an alternate preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As stated above, the present invention provides a multiple-pivot apparatus that can lift, excavate, secure, split and/or crush tree stumps, as well as other materials, particularly other wooden materials. 
     Referring now to FIGS. 1 and 5, a tree stump lifting and crushing apparatus  10  of the present invention is shown. The apparatus generally comprises three main components, an arm-like supporting structure  11 , an engaging unit  12 , and a cutting device  13 . In a preferred embodiment, these components are made of mild and high carbon steel, e.g., T 1 , or other suitable metal material. Such materials are commercially available from a variety of steel suppliers. 
     The supporting structure  11  has a curved L-shape and is movably attached at its upper end  11 ′ to a suitable power source, e.g., a hydraulically powered, manipulatable boom such as a bucket arm of a digging machine  27  (as shown in FIG.  5 ). 
     As shown in FIGS. 4A-4B, the supporting structure  11  comprises two reinforcing side plates or sticks  15  and  15 ′, with a stick backplate  16  disposed therebetween. In a preferred embodiment of the present invention, sticks  15  and  15 ′ have a wider diameter at their lower end, to which a similarly shaped reinforcing plate, referred to as supporting plate  17  and  17 ′ is welded or otherwise mountably attached. This design provides additional reinforcement to the supporting structure during the cutting process and avoids destructive engagement of the engaging and cutting device. 
     In a particularly preferred embodiment of the present invention, the lower surfaces of supporting plates  17  and  17 ′ are serated as denoted by reference numeral  30  in FIGS. 4B and 7. The serated edges absorb force and further reduce the opportunity for slippage of the tree stump or other work material during the crushing and excavating operation. 
     The thickness of the sticks  15  and  15 ′ is preferably about 1 to ½ inches, more preferably about ½ to 1 inch, most preferably about 3 inch. The thickness of the supporting structure backplate  16  is preferably about ¼ to ½ inches, more preferably about ½ to 1 inch, most preferably about ¾ inch. 
     As shown in FIGS. 1 and 7, the engaging unit  12  and cutting device  13  are each pivotably and opposedly connected to the lower portion  11 ′ of the supporting structure  11  by means of two pivot pin assemblies  14  and  14 ′, respectively. Referring to FIG. 7, the pivot pin assemblies are shown in partially assembled detail. 
     The multiple pivots of an apparatus of the invention may be suitably spaced apart by a relatively wide range of dimensions. Preferred distances to space the multiple pivots may depend in part on the targeted use of the particular apparatus. More specifically, referring to FIG. 1, pivots  14  and  14 ′ may be suitably spaced (i.e. distance x in FIG. 1) from about 10 inches to 6 feet, more typically distance x being from about 1 foot to about 4 feet. A distance x between pivots  14  and  14 ′ of about 3 feet may be particularly preferred. 
     It also is generally preferable that the length of the engaging unit and cutting or grappling devices be essentially unilateral with respect to the distance between the pivots. Again, referring to FIG. 1, respective distances y and z are preferably substantially equivalent to distance x. In preferred embodiments of the present invention, the configuration of distances x, y and z provide an opening at maximum power of about 6 to about 15 feet, more preferably of about 7 to about 12 feet. 
     Referring to FIGS. 2 and 7, the engaging unit  12  comprises two side plates  18  and  18 ′, with each side plate having a spear-like extension,  19  and  19 ′ respectively, extending from its leading edge, and a backplate  20  securely disposed therebetween. In a preferred embodiment, extensions  19  and  19 ′ comprise replaceable teeth with a cap pinned to a shank unit which are welded to side plates  18  and  18 ′. The backplate  20  provides significant support and reinforcement to the engaging unit  12  during the lifting, excavating, splitting and crushing process. The planar design of the backplate  20  does not invite any clogging or debris from the stumps being crushed. Therefore, opportunity for damage to the apparatus associated with clogging or debris and the downtime associated therewith are substantially eliminated. 
     The thickness of side plates  18  and  18 ′ of the engaging unit  12  is preferably about 1 to 2 inches, more preferably about 1½ inches. The thickness of the engaging unit&#39;s backplate  20  is preferably about 1 to 2 inches, more preferably about 1½ inches. 
     Referring with particularity to FIG. 2D, an alternate preferred embodiment of the engaging unit is shown to include a rake attachment  29 . Using such a configuration, the engaging unit can perform an additional function without disrupting the excavating and cutting operation. For example, the rake attachment  29  can be used as a tool for clearing debris, dirt and the like from the work area during the operation. Such an attachment is typically welded to the engaging unit&#39;s back plate  20  or to a tool bar in proximity thereto. A variety of other attachments also may suitably be used to facilitate various functions, e.g., a blade attachment for specialized excavation, such as that depicted in FIG. 2E as reference numberal  35 . 
     Referring to FIG. 3, the cutting device generally comprises a curved, sharpened outer surface, termed a knife blade  21 . In a preferred embodiment, a similarly curved, elongated knife tooth  22  is mountably attached to the knife blade. The knife tooth provides a penetration point for initiating the splitting process. Preferably, the two sides of the knife tooth  22  and  22 ′ extend across about the lower ⅔ section of the knife blade  21 . The knife tooth is preferably made from AR 400 steel (an abrasive resistant form of T- 1 ). 
     A knife tooth plate  23  is disposed between the two sides of the knife tooth and provides reinforcement and strength to the cutting device structure during the tree stump splitting and crushing process. The knife tooth plate  23  also increases the wear-resistance and longevity of the device. The knife tooth and knife tooth plate may be removed, sharpened and replaced as necessary. 
     In an alternate embodiment of the present invention, the apparatus  10  comprises a grappling unit  28 . Referring to FIG. 6, grappling units  28  and  28 ′ extend from either side of pin assembly  14 ′ and connect to the respective sides of knife tooth  22  and  22 ′. The grappling unit may be used in addition to the cutting device components described above, or it may be manufactured as a stand-alone unit. As should be understood from FIG. 6, with grappling unit  28 , apparatus  10  can be employed to haul or otherwise transport any of a variety of materials, including tree stumps or other loads that may be present at an excavation site. Additionally, by employing the multiple spaced pivots for engaging and grappling units, greater volumes of materials can be lifted and transported with an apparatus of the invention, relative to prior grappling systems. 
     As in the case of the knife tooth, the other components of the cutting device are preferably made from AR 400 steel (an abrasive resistant form of T- 1 ). 
     The thickness of the sides of the knife tooth  22  and  22 ′ and the knife tooth plate  23  are preferably ¼ to 1 inch, more preferably about 2½ inch. The thickness of the knife blade  21  is preferably about 2 to 4 inches, more preferably about 2½ inches. 
     Referring to FIGS. 1,  4 A and  5 , a plurality of anchor hooks  24  protrude from each of the outer surfaces of sticks  15  and  15 ′ in one preferred embodiment of the present invention. The anchor hooks  24 , preferably welded to the sticks  15  and  15 ′, provide a means of securing a first and second reinforcing member  25  and  25 ′ (shown in FIG. 5) on either side of the sticks  15  and  15 ′. Typically, one end of the reinforcing member  25  is mounted to one or more of the anchor hooks  24 ; the other end is secured to, e.g., connected and/or in communication with, the pivot point assemblies  14  and  14 ′. This novel aspect of the present invention provides additional support and durability to the apparatus during the tree lifting and crushing operation. Further, this design provides significant ease of operation in terms of mounting and dismounting attachments relative to an excavator. 
     In an alternate preferred embodiment of the present invention, the first and second reinforcing members  25  and  25 ′ are secured to the supporting structure by a plurality of clamps  31  and case hardened steel pins  32  (shown in FIG.  7 ). Such a configuration eliminates the need for welding anchor hooks or a similar structure on the sticks of the apparatus, thus eliminating the possibility of damage to the boom, e.g., cracks and the like, which may result as a consequence of welding. 
     Referring with particularity to FIG. 5, movement and communication of the engaging unit  12  and cutting device  13  are facilitated by auxiliary hydraulic circuits, designated herein as hydraulic cylinders  26  and  26 ′. On one side of the supporting structure, a first hydraulic cylinder  26  is attached at one end to an aperture  28  on reinforcing member  25 . Referring also to FIG. 7, the other end of the hydraulic cylinder is attached to a rear portion  33  of engaging unit  12 . On the other side of the supporting structure, a second hydraulic cylinder  26 ′ connects reinforcing member  25 ′ to a rear portion, e.g., aperture  34 , of cutting device  13 . In a preferred embodiment, case hardened steel pins  32  are used to facilitate these attachments. 
     The two hydraulic cylinders  26  and  26 ′ can be manually retracted and extended using hydraulics controlled from the cab of the digging machine. This operation facilitates movement and communication of the engaging unit  12  and cutting device  13  during the tree stump lifting and crushing process. 
     Further, the novel configuration of the present invention provides a crushing device which offers maximum power (force) when the engaging unit and cutting or grappling devices are in an open position, e.g., positioned at a 90° angle with respect to the arm-like supporting structure. 
     Referring again to FIG. 5, the tree stump lifting and crushing operation can be illustrated as follows. Using hydraulics controlled from the cab of the digging machine, the operator of the digging machine can move the bucket arm of the digging machine  27  to deploy the arm-like supporting structure  11  to the desired location in proximity of the targeted tree stump. The engaging unit  12  and cutting device  13  are then drawn back and apart utilizing their respective hydraulic cylinders  26  and  26 ′ and pivot point assemblies  14  and  14 ′. The tree stump then can be grasped, lifted and positioned securely against engaging unit  12 . 
     While the stump is securely held by engaging unit  12 , splitting and crushing of the stump is effected by retracting and releasing the cutting device  13  utilizing hydraulic cylinder  26 ′ and the hydraulic controls associated therewith. Depending upon the length and size of the stump, this movement can be repeated as necessary to effect the desired degree of crushing of the stump. 
     The terms and expressions which have been employed herein are used as terms of description and not of limitation. There is no intent, in the use of such terms and expressions, of excluding any of the equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.