Patent Publication Number: US-2007110553-A1

Title: Hydraulic grapple apparatus and method for use of same

Description:
TECHNICAL FIELD OF THE INVENTION  
      This invention relates, in general, to skid steer loaders and, in particular, to a hydraulic grapple apparatus that attaches to a skid steer loader and provides for gripping, lifting, transporting, and releasing large containers such as plastic containers containing nursery stock.  
     BACKGROUND OF THE INVENTION  
      In gardening, and nursery work, it is very often necessary to rearrange large containers housing trees or other nursery stock within a nursery or tree farm prior to the time of sale when it becomes necessary to load the large containers onto trucks for delivery. Similarly, at the delivery site, the large nursery containers are moved from the delivery trucks to selected locations for planting. The combination of the irregular size and heavy weight of the large nursery containers posses the risk of back and muscle injuries to individuals or even teams of individuals that attempt to move or load the large nursery containers.  
      Therefore, the transportation of large nursery containers usually requires the utilization of a loading vehicle such as skid steer loader. The wide variety of work tools, such as pallet forks, utility buckets, and utility forks, for example, available for skid steer loaders have proven inadequate, however, for moving and loading large nursery containers. By way of example, pallet forks require the use of a pallet which may not be available or, if available, the pallet may not be properly pre-positioned under the large nursery container. By way of another example, utility forks often inadvertently pierce the large nursery containers with their prongs. The piercing and cracking of large nursery containers is particularly acute with respect to plastic containers. Accordingly, a need exists for improvements to work tools for skid steer loaders. In particular, a need exists for a work tool that provides for gripping, lifting, transporting, and releasing large nursery containers such as plastic containers.  
     SUMMARY OF THE INVENTION  
      A hydraulic grapple apparatus and method for use of the same are disclosed that provide for the efficient and safe gripping, lifting, transporting, and releasing of large containers such as plastic nursery stock containers. In one embodiment, the hydraulic grapple apparatus includes a support frame for attachment to a skid steer loader. The support frame has upper and lower guide tracks arranged in vertical alignment with each other and spaced apart in order to define an open channel therebetween. First and second grapple jaws are mounted on the upper and lower guide tracks for lateral movement along the support frame. First and second double-acting hydraulic cylinders are disposed in the open channel and are coupled to the support frame. The first and second double-acting hydraulic cylinders independently actuate the first and second grapple jaws, respectively. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which:  
       FIG. 1  is a front perspective view of one embodiment of a skid steer loader utilizing a hydraulic grapple apparatus in accordance with the teachings presented herein;  
       FIG. 2A  is a top plan view of one embodiment of a hydraulic grapple apparatus preparing to grip a container having nursery stock;  
       FIG. 2B  is a side view of the hydraulic grapple of  FIG. 2A  taken along line  2 B- 2 B′;  
       FIG. 3A  is a top view of the hydraulic grapple apparatus of  FIG. 2A  gripping and transporting the container;  
       FIG. 3B  is a side view of the hydraulic grapple of  FIG. 3A  taken along line  3 B- 3 B′;  
       FIG. 4A  is a top view of the hydraulic grapple apparatus of  FIG. 2A  releasing the container;  
       FIG. 4B  is a side view of the hydraulic grapple of  FIG. 4A  taken along line  4 B- 4 B′;  
       FIG. 5A  is a front perspective view of one embodiment of a grapple jaw traversing upper and lower guide tracks in accordance with the teachings presented herein;  
       FIG. 5B  is a side view of the grapple jaw of  FIG. 5A  taken along line  5 B- 5 B′;  
       FIG. 6  is a top plan view of another embodiment of a hydraulic grapple apparatus;  
       FIG. 7  is a front plan view of one embodiment of a hydraulic grapple apparatus wherein the grapple jaws are not illustrated in order to show double-acting hydraulic cylinders in further detail;  
       FIG. 8  is a schematic diagram of one embodiment of double-acting hydraulic cylinders coupled to a hydraulic system in order to actuate the grapple jaws; and  
       FIG. 9  is a side view of a presently preferred, exemplary embodiment of the hydraulic grapple apparatus. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the present invention.  
      Referring initially to  FIG. 1 , therein is depicted one embodiment of a skid steer loader  10  utilizing a hydraulic grapple apparatus  12  in accordance with the teachings presented herein. The skid steer loader  10  includes a body  14  that houses the powertrain and drive system. In one implementation, the powertrain includes a diesel engine and a set of hydraulic pumps. The drive system may be a “no transmission” based system wherein a hydraulic motor and set of sprockets provide power to each wheel. A cage  16  forms a portion of the body  14  and provides a partially enclosed seating area that enables an operator to use controls positioned therein. Four wheels, including wheels  18 ,  20 , and  22 , provide maneuverability in tight spaces and permit the skid steer loader  10  to turn within its own footprint. It should be appreciated that the skid steer loader  10  may be outfitted with multi-terrain tracks instead of wheels to increase traction in slippery conditions like mud or snow and reduce soil compaction, for example.  
      Loader arms  24  and  26 , which together define a hydraulic power lift, and their associated hydraulics are designed to hold a variety of implements and provide lifting capability. In one embodiment, the loader arms  24  and  26  lift the hydraulic grapple apparatus  12  in an arc such that as the hydraulic grapple apparatus  12  rises, it first moves out and away from the skid steer loader  10  before moving closer to the skid steer loader  10  as the hydraulic grapple apparatus  12  moves to a point higher than the skid steer loader. With this arrangement, the hydraulic grapple apparatus  12  sits close to the skid steer loader  10  in the down position to ensure that the skid steer loader  10  is more compact and stable. As the hydraulic grapple apparatus  12  is raised, it moves away from the skid steer loader  10  to provide more reach and make positioning cargo such as a container easier.  
      As illustrated, the hydraulic grapple apparatus  12  is attached to the skid steer loader  10 . More specifically, the hydraulic grapple apparatus  12  includes a support frame  28  having brackets  30  and  32  for attachment to the loader arms  24  and  26 , respectively. The support frame  28  also includes upper and lower, i.e., first and second, guide tracks  34  and  36  arranged in vertical alignment with each other and spaced apart by end blocks  38  and  40  such that an open channel  42  is defined between by the upper and lower guide tracks  34  and  36 . The end blocks  38  and  40  aid in dispersing load and torque throughout the support frame  28 .  
      Grapple jaws  44  and  46  are mounted on the upper and lower guide tracks  34  and  36  for independent lateral movement along the support frame  28 . The grapple jaws  44  and  46  are hydraulically actuated as will be discussed in further detail in  FIG. 8 . In one particular implementation that will be discussed in further detail in  FIG. 7 , double-acting hydraulic cylinders may be disposed in the open channel  42  and coupled to the support frame  28  or end blocks  38  and  40  in order to provide for the hydraulic actuation of the grapple jaws  44  and  46 . According to this arrangement, the double acting hydraulic cylinders receive operating power from the hydraulic power system of the tractor, and the jaws can be extended and retracted independently of each other. This arrangement makes possible the precise positioning and gripping engagement of the grapple jaws around a container so that the container can be lifted, transported, and released without damaging the container. In particular, the precise positioning and gripping engagement enable the grappling of plastic containers without damaging the containers.  
       FIGS. 2A through 4B  show the efficient and safe gripping, lifting, transporting, and releasing of large nursery stock by one embodiment of a hydraulic grapple apparatus  60 . More specifically,  FIGS. 2A and 2B  depict the hydraulic grapple apparatus  60  preparing to grip a container  62  having large nursery stock, which is illustrated as a tree  64 , that is resting on the ground as indicated by numeral  66 . As depicted, the container  62  includes layers of tight burlap mesh that encapsulate the root system of the tree  64 . It should be appreciated, however, that the hydraulic grapple apparatus presented herein may be utilized with other types of containers and cargo. In particular, the hydraulic grapple apparatus presented herein may be utilized with large plastic containers without breaking or cracking the plastic container.  
      The hydraulic grapple apparatus  60  includes a support frame  68  having brackets  70  and  72  for attachment to loader arms  74  and  76 , respectively, of a skid steer loader. As an alternative to the bracket attachment system, a universal quick coupler may be employed to attach the hydraulic grapple apparatus  60  to the skid steer loader. Upper and lower guide tracks  78  and  80  are spaced apart such that an open channel  82  is defined therebetween. Grapple jaws  84  and  86  are mounted to the guide tracks  78  and  80 . As illustrated with reference to grapple jaw  86 , each grapple jaw includes a coupling plate having upper and lower support members  88  and  90  and jaw member  92  mounted thereto. Inner gripping surfaces  94  and  96  of grapple jaws  84  and  86 , respectively, are positioned in an opposing relationship and shaped to generally conform to circular shaped containers and optimize the amount of surface area contact therebetween. In one embodiment, the components of the hydraulic grapple apparatus such as the support member, brackets, and grapple jaw, for example, are manufactured from metal and treated with a corrosion-resistant coating.  
      The grapple jaws  84  and  86  move under the power of double-acting hydraulic cylinders such as double-acting hydraulic cylinder  98  that is disposed in the open channel  82 . As indicated by arrows  100  and  102 , the grapple jaws  84  and  86  move in a mandibular motion toward each other to releasably grip the container  62 . Once the grapple jaws are positioned proximate to the container  62 , the grapple jaws  84  and  86  contact the container  62  and pull the container  62  towards the support frame  68 . On the other hand, the grapple jaws  84  and  86  move in a mandibular motion away from each other in order to release the nursery container. As indicated by arrow  104 , the loader arms permit the hydraulic grapple apparatus  60  to pivot which aids in not only picking up containers and cargo but placing containers and cargo as well.  
       FIGS. 3A and 3B  depict the hydraulic grapple apparatus  60  gripping and transporting the container  62 . The grapple jaws  84  have independently retracted toward a proximal local of the support member  68  and the container  62  is being held by the inner gripping surfaces  94  and  96  of the grapple jaws  84  and  86 , respectively. The independently controlled movement of the grapple jaws  84  and  86  provides for precise placement of the grapple jaws with the appropriate use of gripping force, thereby ensuring that the container and its contents are not damaged. As indicated by arrows  110 ,  112 , and  114 , once the hydraulic grapple apparatus  60  grips the container  62 , the container may be pivoted, lifted, or carried.  
       FIGS. 4A and 4B  depict the hydraulic grapple apparatus  60  releasing the container  62  on a raised surface  120 , which may be the bed of a delivery truck, for example. As indicated by arrows  122  and  124 , once the container  62  is positioned over the desired destination, the grapple jaws  84  and  86  retract toward the distal ends of the support member  68 , thereby releasing the container. It should be appreciated that the ability of the hydraulic grapple apparatus  60  to pivot as well as raise the container  62  permits the container  62  to be placed on a variety of surfaces of varying heights. Once the container  62  is released, the hydraulic grapple apparatus  60  withdraws under the power of the skid steer loader as indicated by arrow  126 .  
       FIGS. 5A and 5B  depict one embodiment of a grapple jaw  140  traversing partial upper and lower guide tracks  142  and  144  in accordance with the teachings presented herein. The portion of the upper and lower guide tracks  142  illustrated includes the upper and lower guide tracks from a distal end to a proximal local. A support frame  146  and an end block  148  maintain the positioning of the upper and lower guide tracks  142  and  144 . It should be appreciated that the upper and lower guide tracks  142  and  144  may be lubricated or greased so that the grapple jaw  140  traverses the upper and lower guide tracks with minimum friction.  
      The grapple jaw  140  includes a coupling plate  150  having upper and lower support members  152  and  154  that correspond to the upper and lower guide tracks  142  and  144 , respectively. A jaw member  156  is connected to the coupling plate such that an inner grip surface  158  faces the proximal local of the upper and lower guide tracks  142  and  144 . Preferably, the coupling plate  150 , upper support member  152 , lower support member  154 , and jaw member  156  form an integral grapple jaw  140 . With arrangement described, the gripping jaws are coupled for sliding movement during extension and retraction in a sliding “tube within a tube” assembly along the lower and upper guide tracks. This parallel reaction coupling greatly increases the load that the gripping jaws can lift without imposing a damaging torque load on the support frame.  
      In one implementation, layers of grip tape  160 ,  162 , and  164  are affixed to the inner grip surface  158  to improve the gripping ability of the grapple jaw  140 . As previously discussed, in operation, the upper and lower support members traverse the upper and lower guide tracks, respectively to move the grapple jaw  140  toward the proximal local and the distal end.  
       FIG. 6  depicts another embodiment of a hydraulic grapple apparatus  180  which includes a support frame  182  having brackets  184  and  186  for attachment to loader arms  188  and  190 , respectively. Grapple jaws  192  and  194  are mounted to and traverse guide tracks. As illustrated, the hydraulic grapple apparatus  180  is equipped with liners  196  and  198  in order to grip a small container  200 . The liners  196  and  198  are coupled to the grapple jaws  192  and  194 , respectively, by insert mounts  202 ,  204 ,  206 , and  208  having pins which are received in holes  203 ,  205 ,  207 , and  209 , respectively, positioned in the grapple jaws  192  and  194 . It should be appreciated by those skilled in the art that liners of different sizes may be utilized to accommodate containers of various sizes. Further, the shape of the liners does not necessarily have to correspond to the shape of the grapple jaws. Particular liners may be utilized to alter the shape of the inner grip surface of the grapple jaws to be correspond to the shape of the container.  
       FIG. 7  depicts one embodiment of a hydraulic grapple apparatus  220  wherein grapple jaws are not illustrated in order to show particular components in further detail. Upper and lower guide tracks  222  and  224  are vertically spaced apart from each other by end blocks  226  and  228  such that an open channel  230  is defined between the upper and lower guide tracks  222  and  224 . Further, the upper and lower guide tracks  222  and  224  have distal ends as represented by dashed lines  232  and  234  and a proximal local as represented by dashed line  236 .  
      Double-acting hydraulic cylinders  238  and  240  are disposed within the open channel  230  and coupled to the end blocks  226  and  228  as well as to the upper and lower guide tracks  222  and  224  by mounting braces  242  and  244 . With respect to the double-acting hydraulic cylinder  238 , hydraulic fluid hoses  246  and  248  provide for fluid communication between the double-acting hydraulic cylinder  238  and a hydraulic power system associated with the skid steer loader. The double-acting hydraulic cylinder  238  includes an arm  250  having a coupling member  252  for attaching a grapple jaw thereto. Similarly, the double-acting hydraulic cylinder  240  includes hydraulic fluid hoses  254  and  256 , an arm  258 , and a coupling member  260 .  
      With reference to the double-acting hydraulic cylinder  238 , the hydraulic fluid hoses  246  and  248  are used to vary the application of forward and backward pressure to a piston housed therein. As indicated by arrow  262 , the changes in pressure extend the arm  250  and grapple jaw toward the proximal local  236  of the upper and lower guide tracks or retract the arm and the grapple jaw toward the distal end  232 . As indicated by arrows  264  and  266 , when hydraulic fluid flow is increased to a rear chamber within the double-acting hydraulic cylinder  238 , hydraulic fluid exits the double-acting hydraulic cylinder  238  through hose  248  as the arm  250  extends towards the distal local  236 . It should be appreciated that the orientation of the double-acting hydraulic cylinder may be reversed such that the arm and grapple jaw are retracted toward the proximal local or the arm and the grapple jaw are extended toward the distal end.  
       FIG. 8  depicts one embodiment of a hydraulic system  280  that actuates grapple jaws associated with a skid steer loader. As depicted, the hydraulic system  280  includes two halves  282   a  and  282   b  under the control of a controller  284 . For purposes of illustration, the hydraulic system half  282   a  will be described. It should be appreciated, however, that the operation of the hydraulic system half  282   b  is similar to the operation of hydraulic system half  282   a . Further, the components of the hydraulic system half  282   a  are designated by the inclusion in their numeral of the letter “a” while the corresponding components of the hydraulic system half  282   b  are designated by the inclusion of the letter “b”.  
      A double-acting hydraulic cylinder  286   a  includes chambers  288   a  and  290   a  which are partitioned by a piston  292   a . An arm  294   a  is coupled to the piston  292   a  and a grapple jaw may be coupled to the arm as previously described. A spool valve  296   a  is coupled to the chambers  288   a  and  290   a  by fluid control lines  298   a  and  300   a , respectively. A pump  302   a  is in fluid communication with the spool valve  296   a  via fluid control line  304   a . A hydraulic fluid reservoir  306   a  is in fluid communication with the spool valve  296   a  and the pump  302   a  by way of fluid control lines  308   a  and  310   a , respectively. In one implementation, all of the illustrated components except for the double-acting hydraulic cylinders  286   a  and  286   b  form a portion of a hydraulic system that is associated with the skid steer loader. In this implementation, these components of the hydraulic system are connected to the double-acting hydraulic cylinders by the fluid control lines  298   a ,  298   b ,  300   a , and  300   b.    
      In operation, when the operator of the skid steer loader desires to move the grapple jaw associated with the arm  294   a  toward a container or object, the operator uses the controller  284  to signal the spool valve  296   a  to apply forward pressure to the piston  292   a . In one embodiment, the controller may include two joysticks and associated electronics and hydraulics. During this operation, hydraulic fluid flow is increased to chamber  288   a , thereby increasing the pressure in the chamber  288   a  and causing the piston  292   a  and arm  294   a  to extend in the direction indicated by arrow  312 . Further, this extension displaces fluid from the chamber  300   a.    
      On the other hand, when the operator of the skid steer loader desires to move the grapple jaw associated with the arm  294   a  away from the container, hydraulic fluid flow is increased to chamber  290   a , thereby increasing the pressure in the chamber  290   a  and causing the piston  292   a  and arm  294   a  to retract in the direction indicated by arrow  314 , thereby displacing fluid from the chamber  288   a . As previously discussed, controller  284  provides for the independent actuation of the grapple jaws. Therefore, nine operations are possible with respect to arms  290   a  and  290   b  and their respective grapple jaws. Table I summarizes these possible operations.  
               TABLE I                          Arm Operations                                 Operation   Arm 294a   Arm 294b                       One   stationary   stationary           Two   stationary   extending           Three   stationary   retracting           Four   extending   stationary           Five   extending   extending           Six   extending   retracting           Seven   retracting   stationary           Eight   retracting   extending           Nine   retracting   retracting                      
 
      The variety of arm operations ensure precise handling and control of the grapple jaws and the container or cargo. In particular, the grapple jaws enable the handling of large plastic containers without damaging or harming both the container and the nursery stock within the container. Further, the parallel actuation of the grapple jaws greatly increases the load that the skid steer loader can lift without imposing a damaging torque load on the support frame.  
       FIG. 9  depicts a presently preferred, exemplary embodiment of the hydraulic grapple apparatus  320  that includes a support frame  322  for attachment to skid loader mounting bracket  324  of a skid steer loader. A grapple jaw, which is partially shown, includes a support structure  326  having lower plates  328 ,  330  as well as a backing plate  332  and an upright plate  334 . It should be appreciated that a second structural support provides a frame for the other grapple jaw. The upper and lower plates  328 ,  330  are positioned within guide tracks  336  and  338 , respectively, which are coupled to the support frame  322  and arranged in vertical alignment and spaced apart to define an open channel  340 . Double-acting hydraulic cylinders  342  and  344  are positioned within the channel  340  and coupled to the backing plate  332 . As previously discussed, the double-acting hydraulic cylinders  342  and  344  actuate the grapple jaws.  
      While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.