Abstract:
The improved pinching fingers of the present invention are adapted for easy installation and use on conventional front-end loaders and skid steers. The pinching fingers are opened and closed by the hydraulic cylinder or cylinders used to rotate other common implements, eliminating the need for a separate hydraulic power system for opening and closing the fingers. The pinching fingers also include an equalizer bar and a novel linkage assembly that equalize pressure between the claws and thus allow one claw to continue closing even if the other claw is restricted. This feature allows the pinching fingers to more easily and safely handle irregular and tapered items.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is a Continuation-in-Part of application Ser. No. 10/934,749 entitled “Grapple Assembly, A Front End Loader Having a Grapple Assembly, and Method for a Operating a Grapple Assembly” and filed Sep. 3, 2004, the contents of which are incorporated herein by reference. 

   FIELD OF THE INVENTION 
   The present invention relates generally to implements for use with tractors, skid steers and the like, and more specifically to a grappler attachment for use with such vehicles, a vehicle with a grappler attachment and a method for using a grappler attachment. 
   BACKGROUND OF THE INVENTION 
   Tractors and skid steers are common utility vehicles in the farming, construction and landscaping industries. The primary benefit of these vehicles is their great versatility and the wide variety of implements that can be attached to and used with the vehicle. After an initial investment in a tractor or skid steer, owners of these vehicles can add increased functionality by purchasing a wide variety of specialized implements including loaders, backhoes, blades, post hole diggers, forks and bale spears, to name a few. Because of the ubiquity and great versatility of tractors and skid steers, owners of these vehicles continuously seek new and improved implements to perform specialized tasks. 
   Pinching fingers are a good example of an implement that is especially useful for performing a specialized task. Pinching fingers are essentially claws that can be opened and closed around material or an item to be transported by the utility vehicle. Because the pinching fingers can be closed around the material or item, bulky and irregularly shaped items can be picked up and securely held while transported by the utility vehicle. 
   Although they have many uses, pinching fingers are especially useful for transporting logs and clearing brush. Pinching fingers can be clamped around a log so that the log cannot roll when it is picked up, transported and loaded, increasing the safety of working with large logs. Pinching fingers can also be easily clamped around irregularly shaped items such as fallen trees or heavy farm equipment, making it easier to lift and move such items than with conventional implements such as a bucket or forks. 
   Pinching fingers, however, are not easily adapted for use with conventional tractors or skid steers. Most tractors and all skid steers have arms extending from the front of the vehicle for the operation of a loader or other implements. These implements can be raised and lowered by hydraulic cylinders attached to each arm and also rolled forward and backward by a separate cylinder or cylinders. This range of movement (up, down, forward roll and backward roll) is sufficient for operating most common implements including loaders, blades, forks and spears. Thus, two sets of hydraulic controls, one for raising and lowering the implement and one for rolling the implement forward and backward, are standard on most tractors and skid steers. Pinching fingers, however, also requires means for opening and closing the pincer claws. 
   Prior art implements for pinching and grappling a load have been adapted for use with conventional tractors and skid steers. These implements typically utilize a third set of hydraulic controls (or other power means) for opening and closing the pincer claws or grappler. This solution, however, increases the cost of the implement because hydraulic cylinders, couplers and lines must be incorporated into the design of the implement. In the case of a tractor or skid steer that does not already have the necessary controls and lines installed, an entire hydraulic control and power system must be installed on the tractor or skid steer to use the implement. This added cost and complexity has prevented many potential users of pinching fingers and grapplers from adopting this useful implements. Thus, those of skill in the art have sought an implement that can be easily attached to a conventional tractor or skid steer without the need for separate controls and power means for opening and closing the implement. 
   In addition to the problem of requiring a separate set of controls, prior art designs have not been easy to install and remove on a conventional tractor or skid steer. To maximize the versatility and thus the utility of these vehicles, implements must be designed so that they can be quickly interchanged with other implements. Thus, those of skill in the art have sought pinching fingers with simple mechanical means for installing and uninstalling the implement on a conventional tractor or skid steer. 
   Prior art designs also typically suffer from another deficiency in their operation. To provide structural stability and strength, the top set of pincer claws on a conventional grappler are constructed as a unified or solid piece that clamps in opposition to and against a solid bottom set of pincer claws, forks or a bucket. When grasping an item of uniform cross section, this design is adequate for providing uniform pressure at each claw to secure the item. However, when a solid item to be grasped has a tapered or irregular cross section, one claw may be restricted from closing on the item when the other claw closes on a larger portion of the item, causing the item is held by only one claw and not the other. In this instance, the item cannot be safely transported without the danger of the item moving and shifting during transport. Thus, those of skill in the art have sought a grappler and/or pinching fingers with independent claws that can be closed on an item even if another claw is restricted from closing, but without sacrificing the structural stability or strength of the implement. 
   Accordingly, an object of the present invention is to provide pinching fingers for a tractor, skid steer or the like that can be used by the vehicle without the need for an additional set of controls and power means for opening and closing the pinching fingers. 
   A further object of the present invention is to provide pinching fingers that are easy to install and remove on a conventional loader or skid steer. 
   Yet another object of the present invention is to provide pinching fingers that can be quickly interchanged with other implements on a conventional loader or skid steer. 
   An additional object of the present invention is to provide pinching fingers that may move and grasp independently so that both claws securely grasp a solid item of tapered or irregular cross section. 
   A still further object of the present invention is to provide pinching fingers attachment with sufficient structural stability and strength to grasp, lift and transport heavy items including logs, trees and other items. 
   Still another object of the present invention is to provide an improved vehicle with a pinching fingers attachment. 
   Yet another object of the present invention is to provide an improved method for using a pinching fingers attachment with loaders, skid steers and the like. 
   A further object of the invention is to provide a loader or skid steer with pinching fingers that are simple and easy to operate. 
   Finally, an object of the present invention is to provide a pinching fingers attachment that is economical to manufacture, durable and refined in appearance. 
   SUMMARY OF THE INVENTION 
   The preferred embodiment of the present invention provides a pinching fingers implement that can be used with conventional tractors, skid steers and other vehicles with arms for operating implements. The pinching fingers are attached to the ends of the arms of the tractor or skid steer and thus can be raised and lowered like a typical implement. Rather than having their own separate power means for opening and closing, the pinching fingers are opened and closed by the already present hydraulic cylinder or cylinders typically used for rolling an implement forward and backward. A novel linkage configuration enables the pinching fingers to be opened and closed using the existing hydraulic controls on the tractor or skid steer. 
   In addition, the novel linkage configuration allows the pinching fingers to operate independently so that one finger may be closed on an item even if the other finger is restricted from closing. In applicants&#39; patent application Ser. No. 10/934,749, this independence of the fingers is provided by separate hydraulic cylinders that allow one finger to close even if the other is restricted. Although useful for front end loaders, this configuration is not adaptable to skid steers with a single hydraulic cylinder for rotating implements. Also, the configuration of the &#39;749 application is not easily adaptable to quick change connectors that are connected to and rotated by two hydraulic cylinders on a front end loader or skid steer. The novel linkage configuration of the present invention allows the pinching fingers to be used with skid steers having a single hydraulic cylinder or with a quick change connector controlled by two hydraulic cylinders. As described herein, the linkage configuration allows limited independent movement of the pinching fingers although the opening and closing of the fingers are powered by a single hydraulic cylinder or a pair of hydraulic cylinders operating in unison to rotate a quick change connector. 
   The pinching finger of the present invention are easy to install and remove on a conventional tractor or skid steer. The pinching fingers have no hydraulic lines to connect to the tractor or skid steer. Also, the pinching fingers can be easily attached to arms of the tractor or skid steer using conventional pins and bolts. A standardized quick release system may also be used so that the pinching fingers may be even more quickly interchanged with other implements adapted for the quick release system. 
   The pinching fingers of the present invention are simple and easy to operate. The pinching fingers are controlled by the familiar loader controls, making the control of the fingers easier to learn and operate. The pinching fingers require no additional hydraulic connections, hoses, couplers or controls. Because no additional hydraulic components are required, the addition of the pinching fingers to a loader or skid steer does not increase the potential for oil leaks or contamination from additional hydraulic components. Also, no additional hoses are needed, eliminating the possibility that the additional hoses could become torn or frayed. 
   These and other advantages will become apparent as this specification is read in conjunction with the accompanying drawings and appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view of a skid steer with the pinching fingers of the present invention in a closed position. 
       FIG. 2  is a side view of a skid steer with the pinching fingers of the present invention in a slightly opened position. 
       FIG. 3  is a side view of a skid steer with the pinching fingers of the present invention in the fully opened position. 
       FIG. 4  is a front perspective view of the pinching fingers of the present invention. 
       FIG. 5  is a rear perspective view of the pinching fingers of the present invention. 
       FIG. 6  is a front perspective view of the pinching finger of the present invention with the left fingers (shown on the right side of  FIG. 6 ) in a restricted position and the right fingers (shown on the left side of  FIG. 6 ) in a more closed position. 
       FIG. 7  is a side view of a skid steer with the pinching fingers of the present invention with the left fingers in a restricted position and the right fingers in a more closed position. 
       FIG. 8  is a close up side view of the pinching fingers of the present invention with the left fingers in a restricted position and the right fingers in a more closed position. 
       FIG. 9  is a side view of a front end loader with a quick connector and the pinching fingers implement of the present invention prepared for attachment to the quick connector of the front end loader. 
       FIG. 10  is a close up side view of the pinching fingers implement of the present invention prepared for attachment to the quick connector of the front end loader. 
       FIG. 11  is a side view of a front end loader with the pinching fingers of the present invention in a closed position. 
       FIG. 12  is a side view of a front end loader with the pinching fingers of the present invention in a opened position. 
       FIG. 13  is a close up side view of the pinching fingers of the present invention on a front end loader with the left fingers in a restricted position and the right fingers in a more closed position. 
   

   The drawings are not necessarily to scale and certain details unnecessary for an understanding of the present invention have been omitted. The invention is not limited to the particular embodiments illustrated herein. 
   In the Figures, the following reference characters are used: 
     10  pinching finger 
     12  skid steer 
     14  left arm 
     15  right arm 
     16  left lift cylinder 
     17  right lift cylinder 
     18  left top pincer claw 
     19  right top pincer claw 
     20  left bottom pincer claw 
     21  right bottom pincer claw 
     22  left coupler pivot pin 
     23  right coupler pivot pin 
     24  left cylinder ram 
     25  right cylinder ram 
     26  left coupler cylinder 
     27  right coupler cylinder 
     28  left connection point (implement cylinder to plate) 
     29  right connection point (implement cylinder to plate) 
     30  left connection point (implement cylinder to arm) 
     31  right connection point (implement cylinder to arm) 
     32  left pivot pin (top pincer claw to bottom pincer claw) 
     33  right pivot pin (top pincer claw to bottom pincer claw) 
     34  left linkage 
     35  right linkage 
     36  left sleeve 
     37  right sleeve 
     38  left actuator pivot pin (equalizer bar connector to top pincer claw) 
     39  right actuator pivot pin (equalizer bar connector to top pincer claw) 
     40  left compression rod 
     41  right compression rod 
     42  left connection point (sleeve to arm) 
     43  right connection point (sleeve to arm) 
     44  first upper claw 
     45  second upper claw 
     46  first lower claw 
     47  second lower claw 
     48  outer tips of upper claws 
     50  left spacer 
     51  right spacer 
     52  left equalizer bar connector 
     53  right equalizer bar connector 
     54  left arm of equalizer bar 
     55  right arm of equalizer bar 
     56  left linkage connector 
     57  right linkage connector 
     58  equalizer bar 
     60  coupler plate 
     62  left coupler cylinder bracket 
     63  right coupler cylinder bracket 
     64  left spring 
     65  right spring 
     66  front end loader 
     68  quick connector 
     70  link 
     71  connection point 
     72  link 
     74  quick connector plate 
   DETAILED DESCRIPTION 
   The present invention may be used with any vehicle having arms for raising and lowering, and also rolling forward and backward, an implement. Although the preferred embodiment of the present invention is intended and adapted for use with a loader or skid steer, those of skill in the art will recognize that the present invention is equally adaptable for use with other utility vehicles including four wheelers and bulldozers. However, for descriptive purposes, the present invention will be described in use on a tractor and/or skid steer. 
     FIGS. 1-3  show the pinching fingers  10  of the present invention attached to a skid steer  12 . In this side view, the left side of the skid steer  12  is shown. The skid steer  12  includes a left arm  14  that can be raised and lowered by the left lift cylinder  16 . The pinching fingers  10  include a left top pincer claw  18  and a left bottom pincer claw  20 . For purposes of describing the operation of the pincer claws  18  and  20  in conjunction with  FIGS. 1-3 , the left side components will be discussed, although it will be understood that the corresponding right side components are also provided and operate similarly. 
   The left bottom pincer claw  20  is fixedly attached to a plate (not shown in this view) that is in turn rotatably connected to the left arm  14  at the left coupler pin  22 , allowing the left bottom pincer claw  20  to rotate about the left coupler pivot pin  22 . The plate is also attached to the end of the cylinder ram  24  of the left coupler cylinder  26  at the connection point  28 . The other end of the left coupler cylinder  26  is connected to the left arm  14  at the connection point  30 . 
   The left top pincer claw  18  is rotatably attached to the left bottom pincer  20  claw at the left pivot pin  32 , allowing the left top pincer claw  18  to rotate about the pivot pin  32 . The left top pincer claw  18  is also attached to the left arm  14  through the left linkage  34  (the components of which are described in detail below) and left compression rod  40 . The left linkage  34  is attached to the left top pincer claw  18  at the left actuator pivot pin  38  and also the left pivot pin  32  where the top and bottom pincer claws are connected. The left linkage  34  is attached to the left compression rod  40 , which slides through the left sleeve  36 . The left sleeve  36  is rotatably connected to the left arm  14  at the left connection point  42 . The left compression rod  40  is biased outward from the left sleeve  36  by the left spring  64 . 
   When actuated, the left coupler cylinder  26  rotates the plate and attached left bottom pincer claw  20  about the left coupler pivot pin  22 , as shown in  FIGS. 1-3 . In the fully closed position, shown in  FIG. 1 , the left linkage  34  closes the left top pincer claw  18  relative to the left bottom pincer claw  20 . In the slightly open position, shown in  FIG. 2 , the left coupler cylinder  26  has rotated the plate and attached left bottom pincer claw  20  forward. The left top pincer claw  18  has also rotated forward, but the left linkage  34  has caused the left top pincer claw  18  to open relative to the left bottom pincer claw  20 . 
   In the fully open position, shown in  FIG. 3 , the left coupler cylinder  26  has rotated the plate and attached left bottom pincer claw  20  fully forward. The left linkage  34  has caused the left top pincer claw  18  to rotate fully about the pivot pin  32  so that the pincer claws are in a fully open position. Thus, the opening and closing of the pincer claws  18  and  20  is fully controlled by the coupler cylinder  26 . The pincer claws  18  and  20  may be raised and lowered by the hydraulic cylinder  16  and arm  14 , and opened and closed in any vertical position, allowing items to be picked up off the ground and loaded or unloaded from or into vehicles. 
   The arm  14  and hydraulic cylinders  16  and  26  are conventional components on any skid steer  12 . Corresponding components are found on any tractor (or other vehicle) with a front-end loader, which includes most tractors. Thus, the pinching fingers  10  of the present invention can be raised, lowered, opened and closed with the conventional components found on any skid steer and most tractors, providing significant advantages over prior art grapplers and pinching implements that require the added expense and complexity of additional hydraulic cylinders, lines, couplers and controls. 
   Details of the construction of the preferred embodiment of the pinching fingers  10  of the present invention are shown in  FIGS. 4-6 . As shown in  FIG. 4 , the left top pincer claw  18  (shown on the right side of  FIGS. 4 and 6 ) is comprised of two claws, a first upper claw  44  and a second upper claw  45 . The left lower pincer claw  20  is also comprised of two claws, a first lower claw  46  and a second lower claw  47 . The right top pincer claw  19  and right bottom pincer claw  21  are similarly constructed. The upper claws  44  and  45  are joined and welded together at their outer tips  48  so that, when the pincer claws are closed, the upper claws  44  and  45  insert between the lower claws  46  and  47 . In the closed position, the lower claws  46  and  47  prevent lateral movement of the upper claws  44  and  45 , providing increased stability when the pincer claws are closed and grasping an item. 
   The first lower claw  46  and the second lower claw  47  are attached to a left spacer  50 , preferably by welding the arms to the spacer. A corresponding right spacer  51  is also provided. The spacers  50  and  51  provide increased stability for the lower arms and maintain the separation between the lower arms. The spacers  50  and  51  are each attached to the coupler plate  60 , preferably by welding the spacers to the plate. The coupler plate  60  provides rigidity and strength between the left and right pincer claws of the grappler  10  and ensures that the bottom pincer claws  20  and  21  operate in unison. 
   As shown in  FIG. 5 , which shows the rear side of coupler plate  60 , the coupler plate  60  includes a left coupler cylinder bracket  62  and a right coupler cylinder bracket  63  attached to the coupler plate. The brackets  62  and  63  rotatably attach at their lower ends to the arms  14  and  15  of the vehicle at the coupler pivot pins  22  and  23 . The brackets  62  and  63  rotatably attach at their midsection to the cylinder rams  24  and  25  of the coupler cylinders  26  and  27  at the connection points  28  and  29 . The hydraulic cylinders  26  and  27  rotatably attach to the arms  14  and  15  of the vehicle at the connection points  30  and  31 . 
   The coupler cylinder brackets  62  and  63  may be welded to the coupler plate  60  as an integral component of the pinching fingers  10 . The coupler cylinder brackets  62  and  63  may also be adapted for quick connection to the coupler plate  60  to allow for quick removal of the pinching fingers  10  from the tractor or skid steer. 
   Although the pinching fingers  10  of the present invention are shown attached to a skid steer with dual coupler cylinders  26  and  27 , the present invention is equally adaptable for use with a skid steer or other vehicle with a single, central coupler cylinder. To connect to a skid steer with a single coupler cylinder, a single coupler cylinder bracket is used and located on the coupler plate in a position to correspond to the position of the coupler cylinder on the skid steer. 
   Referring to  FIG. 4 , the left linkage  34  includes a left equalizer bar connector  52  that is rotatably connected to the left compression rod  40  and rotatably connected to the upper and lower left pincer claws  18  and  20 . The left linkage  34  also includes a left linkage connector  56  that is connected to the left top pincer claw  18  at the left actuator pivot pin  38 . At its other end, the left linkage connector  56  is connected to a left arm  54  that is welded to the equalizer bar  58 . Corresponding components for the right linkage  35 , including a right equalizer bar connector  53 , a right linkage connector  57  and a right arm  55 , are also shown in  FIG. 4 . Like the left arm  54 , the right arm  55  is welded to the equalizer bar  58 . The left arm  54  and the right arm  55  of the equalizer bar  58  are oriented in opposite directions. In the position shown in  FIG. 4 , the left arm  54  is oriented upwards and the right arm is oriented in a 180° opposite downward direction. Because both arms  54  and  55  are welded to the equalizer bar  58 , the arms maintain the opposite orientation during movement of the grappler. 
   The equalizer bar  58  serves to equalize pressure between the left claw and the right claw, providing an additional novel feature to the present invention. In combination with the compression rods  40  and  41 , the equalizer bar  58  allows limited independent movement of the left and right pincer claws so that the pinching fingers  10  may reliably grasp and secure items of irregular cross section. 
   During operation without restriction, the compression rods  40  and  41 , equalizer bar  58 , arms  54  and  55  and linkage connectors  56  and  57  translate the same movement to the top pincer claws  18  and  19 . As the coupler plate  60  is rolled forward by the coupler cylinders  26  and  27 , the actuator pivot pins  38  and  39  are pulled backward relative to the pivot pins  32  and  33 , opening the claws. As the coupler plate  60  is rolled backwards, the left and right arms  54  and  55  of the equalizer bar  58  work in tandem to exert forward force through the linkage connectors  56  and  57  on the top pincer claws  18  and  19  at the actuator pivot pins  38  and  39 . This forward force on the top pincer claws  18  and  19  causes the pinching fingers  10  to close as the coupler plate  60  is rolled backward. 
   However, when one claw is restricted from closing, the equalizer bar  58  allows the other claw to continue closing.  FIGS. 6 and 7  illustrates the operation of the equalizer bar  58  when one claw is restricted. As shown in  FIG. 6 , the left top pincer claw  18  has been restricted from closing by an object, not shown, and the coupler plate  60  has been rolled backward past this point of restriction. The right top pincer claw  19  has continued closing because the restriction on the left top pincer clause  18  causes the left arm  54  of the equalizer bar  58  to rotate backward, which in turns rotates the right arm  55  forward. This forward rotation of the right arm  55  closes the right top pincer claw  19  even though the left top pincer claw  18  is restricted.  FIG. 8  provides a close up side view of the operation of the linkage  34  when the left top pincer claw  18  is restricted. 
   Thus, the novel linkage configuration of the present invention provides many advantages over conventional grapplers and pinching implements. The novel linkage configuration allows the pinching fingers to securely grasp items with a tapered or irregular cross section, including trees and logs, making the transport of heavy and cumbersome items much safer. The equalized pressure on the claws also provides more secure and reliable transport of branches and brush, as well as loose, bulk material such as straw and hay. These and other advantages will be readily apparent to those of skill in the art. 
   The pinching fingers  10  of the present invention are also easily adaptable for use with a front end loader  66  commonly found on tractors. As shown in  FIGS. 9 and 10 , a front end loader  66  may be provided with a quick connector  68 . Referring to the left side of the loader, the quick connector  68  is connected to the arm  14  of the front end loader  66  at the coupler pivot pin  22 . The quick connector  68  may be rotated about the coupler pivot pin  22  by operation of the coupler cylinder  26 . The cylinder ram  24  is attached to the quick connector  68  by the links  70  and  72  at the connection point  71 . Corresponding connections and links are provided on the right side of the loader. The pinching fingers  10  are provided with a quick connector plate  74  that mates with and attaches to the quick connector  68 . The quick connector  68  allows different sized loaders and specialized implements to be quickly attached, removed and changed from the front end loader. 
   When connected to the quick connector  66 , the pinching fingers  10  may be opened and closed by retraction and extension of the coupler cylinders  26  and  27 , as shown in  FIGS. 11 and 12 . Although adapted for use with a front end loader, the linkage  34  operates as described above to open and close the pinching fingers  10 . Also, when one set of fingers is met with a restriction, as shown in  FIG. 13 , the other set of fingers may continue to close. 
   Other alterations, variations, and combinations are possible that fall within the scope of the present invention. Although the preferred embodiments of the present invention have been described, those skilled in the art will recognize other modifications that may be made that would nonetheless fall within the scope of the present invention. Therefore, the present invention should not be limited to the apparatus and method described. Instead, the scope of the present invention should be consistent with the invention claimed below.