Abstract:
An prehensile excavator bucket includes a bucket and a reinforced thumb hingedly affixed to the bucket and that is controlled in conjunction with the bucket for purposes including seizing very heavy items. The thumb may be a single internally-static unit having multiple tines reinforced with metal tubes. The prehensile bucket may have a quick couple receptor so that it can be quickly attached to and detached from an excavator stick with a quick couple mechanism. Because the thumb is permanently attached to the bucket, the thumb and bucket together form a single unit strong enough for gripping and moving very heavy items.

Description:
[0001]    This application claims the benefit of and incorporates by reference Provisional Patent Application No. 61/012,385, filed on Dec. 7, 2007. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to engineering vehicles and more particularly to a prehensile bucket attachment for an excavator or backhoe. 
       BACKGROUND 
       [0003]    An excavator is a type of engineering vehicle that may be used for purposes including construction, demolition and excavation. A bucket is an attachment to an excavator that is used, among other things, for scooping, digging, and excavation. A thumb is an accessory device for an excavator, and may be welded or attached to the excavator&#39;s stick to provide opposable force to the bucket. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  is a perspective view of a first embodiment of a prehensile bucket. 
           [0005]      FIGS. 1A and 1B  are side elevational and rear elevational views of an embodiment of Applicant&#39;s novel prehensile bucket with a thumb attached to a bucket having recessed ears. 
           [0006]      FIGS. 1C ,  1 D,  1 E, and  1 F are views of Applicant&#39;s prehensile bucket having external (non-recessed) ears for engagement to an excavator with or without a quick coupler receptor. 
           [0007]      FIG. 2  is a perspective view of a first embodiment of a bucket configured to receive a thumb and to form a prehensile bucket. 
           [0008]      FIG. 2A  is a partial side elevational view of a quick coupler mechanism engaging the bucket. 
           [0009]      FIG. 2B  is a partial side elevational view of a tine tip showing engagement with a tip tooth. 
           [0010]      FIG. 3  is a first embodiment of a reinforced thumb adapted to attach to a bucket to form a prehensile bucket. 
           [0011]      FIG. 4  is a breakout perspective view of a first embodiment of a reinforced thumb also showing hydraulic cylinders and connectors. 
           [0012]      FIG. 5  is a breakout perspective view of hydraulic hoses and connectors for use in an embodiment of a prehensile bucket. 
           [0013]      FIG. 6  is a perspective view of an excavator equipped with a prehensile bucket. 
       
    
    
     SUMMARY OF THE INVENTION 
       [0014]    With reference generally to the Figures and the specification set forth herein, an embodiment of Applicant&#39;s invention includes an attachment for an engineering vehicle having a stick and an engineering vehicle hydraulic system. The attachment would typically comprise a bucket, the bucket having a cavity, a mouth, a bottom front edge, a top front edge, side walls, a top wall, a curved rear wall, and a bottom wall. The bucket typically includes teeth at the lower front edge thereof, the teeth having interteeth spaces. The bucket may include a pair of spaced apart thumb support members and a pair of thumb retainer pins engaged therewith. The bucket would typically include a pair of spaced apart hydraulic cylinder engaging members located on a bucket top and spaced away from thumb support members on the bucket external walls and toward a curved portion of the bucket. Hydraulic cylinder engaging members of the bucket would also typically include a pair of hydraulic cylinder retainer pins. The bucket includes upper and lower stick engaging members or pins and thereupon, stick engaging members typically located inboard of the thumb support members and the hydraulic cylinder engaging members, and the upper and lower stick engaging members for coupling to the stick which in turn will raise and lower, extend and retract the bucket. 
         [0015]    A pair of hydraulic cylinders are included in Applicant&#39;s prehensile bucket with each hydraulic cylinder having a first end and a second end and constructed in a unique manner for use with respect to engineering vehicles. All cylinders have ports, but these cylinders have a single block port at the rear, connected by a hard line tubing to the front of the cylinder. 
         [0016]    A thumb is provided for pivotal engagement with Applicant&#39;s bucket, the thumb having multiple tines. The tines trend generally transverse between the top and bottom front edges at least partially across the mouth of the bucket and have tine tips at the removed ends thereof. The thumb is pivotally engaged to the bucket for moving between an opened and a closed position. Typically, at least some of the tine tips engage the interteeth spaces of the bucket. Typically, an outboard pair of the multiple tines have a near end adapted to engaging the thumb support members and the hydraulic cylinders. The thumb includes at least one spacing member to laterally space the multiplicity of tines apart from one another yet attach the tines so that the combination of the tines and the at least one spacing member pivots causing the thumb to act as a unit. 
         [0017]    The thumb and the bucket mouth define a jaw. The bucket may also include a hydraulic subsystem for fluidly engaging the hydraulic cylinders of the hydraulic system from the engineering vehicle and a lever mounted in the control cab for selectively expanding and contracting the hydraulic cylinder and thereby opening and closing the jaw of the attachment. 
         [0018]    In one aspect, a prehensile excavator bucket includes a bucket and a reinforced, moveable thumb attached to the bucket that is controlled in conjunction with the bucket for purposes including seizing very heavy items. The thumb may be a single internally-static unit having multiple tines reinforced with metal tubes. The prehensile bucket may have a quick couple mechanism so that it can be quickly attached to and detached from an excavator stick. Because the thumb is attached to the bucket and not the stick, the thumb and bucket together form a single unit strong enough for gripping and moving very heavy items. 
         [0019]    The bucket and thumb combination is designed for use on any size hydraulic excavators, compact hydraulic excavators and backhoe loaders, including without limit, rubber-tire backhoe loaders. This device combines the design of a coupler bucket with a light, yet durable hinging hydraulic thumb. The design effectively maintains the time saving advantages gained by the application of a quick coupler, while providing an excavator with improved versatility and maximized performance. The design allows any hydraulic excavator or backhoe loader equipped with a thumb hydraulic circuit to be tooled and ready in minutes rather than in hours. 
         [0020]    The bucket and thumb act in unison; one cab mounted hydraulic control lever allows the opening and closing of the jaws defined by the thumb and bucket. This allows greater work efficiency, agility, control safety, and ease of operation. The alternative has been to use a thumb that would manually (with a hydraulic control lever) chase the bucket to stay closed on a load. Therefore, this new combination design is inherently safer. The design, because of its secure grip and single lever control, is safer than previous conventional designs. 
         [0021]    An embodiment of the design has dual cylinders for double the force available on the older typical single cylinder thumbs. This provides a gripping force in a magnitude capable of lifting the machine that operates it in most cases. The dual cylinder and cross tube thumb construction contribute to its resistance to tensional frame loads that exceeds the existing excavator thumb styles. The spacing of the tubes eliminates some of the usual operator vision blind spots. 
         [0022]    There is usually no welding required to install an embodiment of this design to an excavator machine, only the plumbing of the hydraulics to the machine fluid supply. An embodiment of this design is created to be a single tool with no special paraphernalia to keep track of. The operation of this new bucket and thumb combination has been compared to pliers for an excavator. The device has been used for building stone walls, excavating building and loading debris, clearing fallen timbers and pulling concrete piers from the earth. 
         [0023]    Hydraulic cylinders, typically a pair, operate between a rear face of a rear wall of the bucket fully retracting to open jaws enough to dig with the bucket and to maintain a proper digging angle. 
         [0024]    When the tines are fully closed, the cylinders are at or near maximum extension. When the jaw is fully open, the cylinders are at or near maximum retraction. The moment arm driving the thumb about the bucket is generally perpendicular to the drive line of the hydraulic cylinders somewhere between the fully opened and fully closed position, typically providing an angular jaw opening of approximately 0-45 degrees. 
         [0025]    Torque tubes perpendicular to the tines are spaced to eliminate operator vision blind spots. 
         [0026]    A single lever is used to control the opening and closing of the thumb which will open and close regardless of the positions of the bucket. 
         [0027]    Grease fittings typically found on all rotating joints, including the joint where the thumb pivots with respect to the bucket and the joint where the cylinders engage the thumb. 
       DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0028]    A prehensile bucket will now be described with more particular reference to the attached drawings. Hereafter, details are set forth by way of example to facilitate discussion of the disclosed subject matter. It should be apparent to a person of ordinary skill in the field, however, that the disclosed embodiments are exemplary and not exhaustive of all possible embodiments. 
         [0029]      FIG. 1  is a perspective view of an exemplary embodiment of a prehensile bucket, which may be adapted for use with an engineering vehicle, for example a 40,000-pound operating weight excavator. A prehensile bucket  100  includes a bucket  102  and a thumb  104 . The bucket  102  and thumb  104  are attached at a pivot point  110 , which allows thumb  104  to hingedly rotate with respect to bucket  102 . Hinged rotation is actuated by a hydraulic subsystem  106  (see also  FIG. 5 ). Bucket  102  may include teeth  204 , each of which may include a tooth tip  112 . An angle called the opening angle  120  may be described by two line segments. The first line segment FLS joins pivot point  110  to tooth tip  112  or a similar extremity. The second line segment SLS joins pivot point  110  to pivot point PV (where the cylinders pivot against the bucket. The opening angle varies as thumb  104  moves from a fully closed position to a fully open position. In the fully-closed position ( FIG. 1 ), the angle between the line segments may be approximately 84 degrees. For simplicity, the fully-closed position may be used as a reference angle  120 , and the opening angle  108 - 1  (see  FIG. 1C ) may be described as an offset from that position. So in the fully-closed position, the opening angle is 0 degrees. In the depicted embodiment, the maximum opening angle  108 - 1  (when thumb  104  is fully open) may be at least 95 degrees (a total angle of 179 degrees between the two line segments). A typical opening angle range is up to about 100 degrees or more, if possible. 
         [0030]    Because thumb  104  hingedly rotates relative to bucket  102 , thumb  104  provides opposable force to bucket  102 , which is similar to the action of fingers opposing thumbs in humans. The provision of opposable force gives the combination of thumb  104  and bucket  102  the ability to grip or grasp objects, including objects that have irregular shapes or are very heavy. This gripping or grabbing constitutes prehensile action by thumb  104  and bucket  102 . 
         [0031]      FIG. 2  provides a reference to different areas or sections on bucket  102 . Bucket  102  includes a top front edge TFE spaced apart from a bottom front edge BFE and a pair of side walls SW, the leading edge of the side walls, TFE and BFE generally defining a bucket mouth M. The side walls engage a rear wall having a top wall TW, a curved wall CW, and a bottom wall BW. 
         [0032]      FIG. 2  is a perspective view of an exemplary embodiment of a bucket  102  configured to receive a thumb  104 . The bucket  102  includes a cavity  202  with a selected volumetric capacity. Teeth  204  aid in digging and cutting. Bucket torque tubes  206  are provided as a mounting point for pivot mount ears  410 - 1  and  410 - 2  ( FIG. 1 ). A quick couple receptor  212  may be provided for interfacing with a quick couple mechanism on an excavator. Side cutters  208  are also shown, which may be welded on to the bucket  102  or may be bolted on. Wear plates  210  provide protection against wear on the bucket structure, and in some embodiments, may be constructed of metal, or alternatively of acetyl or any natural, synthetic or composite material appropriate for providing a wear buffer to the bucket  120 . 
         [0033]      FIG. 3  is an exemplary embodiment of a reinforced thumb  104  adapted to attach to bucket  102  ( FIG. 1 ). Thumb  104  includes a plurality of tines  302 , which together form a single, internally static unit, meaning the tines are not intended to move with respect to each other. The tines  302  may be separated and reinforced by reinforcing pipes or torque tubes  304  which may be steel tubes. In other embodiments, tines  302  may be separated and supported by other structures, such as steel plates, braces or bars. The tines can be constructed of 1¼ inch-thick metal, but may also vary in a range of between ¾ inch and 1½ inch or any suitable thickness. The two outer tines are attached to a pivot arm  306  including two pivot arm plates  308 - 1  and  308 - 2 . Pivot arm plates  308  may be separated and braced by arm spacers  314  and by pivot arm bosses  316 . A replaceable pivot arm bushing  318  may be seated inside each pivot arm boss  316 . Grease (Zerk) fittings  323  may be provided as shown. There are also holes  322  adapted to receive a hydraulic pin retainer  320 . Hydraulic pin retainer  320  retains pin  321  (see  FIG. 4 ) and is adapted to allow connection to the hydraulic cylinders of the hydraulic subsystem  106 . In this embodiment, the pivot arm plate  308  may be constructed of ¾ inch metal or a range of between ½ inch and 1½ inch metal. 
         [0034]      FIG. 4  is a breakout view of a first embodiment of a reinforced thumb, also showing hydraulic cylinders and connectors. Hydraulic subsystem  106  engages hydraulic cylinders  402 . Hydraulic cylinders  402  may include hard line conduits  404 . The hard line conduits  404  may be constructed of the same or a similar metal as the outside of the hydraulic cylinders  402 . The hard line conduits  404  are terminated at one end by a port block  406 . The hydraulic cylinders  402  may connect via boss fitting  418  to thumb  104  at the hydraulic cylinder holes  322 . Grease fittings  323  may be provided as shown. The thumb  104  is also connected at pivot arm boss  306  to pivot mount ears  410 . Pivot mount ears  410  are welded on to the bucket. A bent plate cover  408  may be added to protect the hydraulic supply hoses  502  ( FIG. 5 ) from cuts and abrasions while the attachment is in operation. A pair of cylinder/bucket pivot plates  412 - 1  and  412 - 2  provide engagement with either side of hydraulic cylinders  402 - 1  and  402 - 2  for attachment (pivotally) of the cylinders with the bucket (see  FIG. 4 ). 
         [0035]      FIG. 5  is a detailed view of an embodiment of a hydraulic subsystem  106 , with hydraulic cylinders  402  ( FIG. 4 ) omitted to provide a more detailed view of other elements. Hydraulic hoses  502  are provided to route hydraulic fluid to the hydraulic cylinders  402  ( FIG. 4 ), and may be constructed of a heavy-duty reinforced rubber, such as the steel-ribbed Aeroquip™. Hydraulic hoses  502  may be joined by hydraulic connectors  506 . Hydraulic hoses  502  may be secured by retaining blocks  504 . Supply and return lines  509  tie into bulkhead fittings  613  (see also  FIG. 1 ) for receiving. 
         [0036]      FIG. 6  is a side view of an exemplary embodiment of an excavator  610  equipped with a prehensile bucket attached. Excavator  610  includes a stick member  612 . The stick  612  is adapted to receive an attachment, which in this case is a prehensile bucket  100 . Stick  612  may include a quick couple mechanism ( FIG. 2A ) that is adapted to interface with a quick couple receptor  212 . Control lever  611  controls jaw opening. Supply and return lines  609  engage hydraulic subsystem  106  to the hydraulic system of the machine, through bulkhead fitting  613  (see  FIGS. 1 and 5 ). 
         [0037]    Although the paragraphs above describe, by way of example, a prehensile bucket  100  suitable for use with a 40,000-pound operating weight excavator, the basic concept of a prehensile bucket  100  may be adapted for use with other sizes of excavators. Table 1 below lists some exemplary characteristics of prehensile buckets that may be used with various sizes of excavators. 
         [0000]    
       
         
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Alternative Embodiments 
               
             
          
           
               
                   
                 Bucket 
                   
                 Tine 
                   
                   
               
               
                   
                 Capacity 
                   
                 Thickness 
                 Typical 
               
               
                 Operating 
                 (Cubic 
                 Total 
                 (Exemplary/ 
                 Opening 
                 Total 
               
               
                 Wt. (Pounds) 
                 Yards 
                 Tines 
                 Range) 
                 Angle 
                 Angle 
               
               
                   
               
             
          
           
               
                 30,000 
                 0.7 
                 4 
                 1 
                 94° 
                 194° 
               
               
                   
                   
                   
                  ¾-1¼ 
               
               
                 40,000 
                 1.3 
                 4 
                 1¼ 
                 95° 
                 179° 
               
               
                   
                   
                   
                  1-1½ 
               
               
                 55,000 
                 1.8 
                 4 
                 1½ 
                 89° 
                 195° 
               
               
                   
                   
                   
                 1¼-1¾ 
               
               
                 70,000 
                 2.2 
                 4 
                 1½ 
                 89° 
                 194° 
               
               
                   
                   
                   
                 1¼-1¾ 
               
               
                 100,000 
                 3.0 
                 5 
                 1½ 
                 103° 
                 204° 
               
               
                   
                   
                   
                 1¼-1¾ 
               
               
                   
               
             
          
         
       
     
         [0038]    Because of these superior characteristics, the present system is useful for easing or enabling numerous tasks that an excavator might perform. For example, an excavator equipped with the present system can firmly grasp a pylori embedded in the ground and pull it out, or pick up and hold a large rock, or more easily collect and move debris. In one embodiment, of the present system, an prehensile bucket can exert a maximum linear force of at least 72,000 pounds. 
         [0039]    Turning back to  FIGS. 1 and 1A , it is seen that an embodiment of the invention comprises a quick couple receptor  212 . More specifically, quick couple receptor  212  is seen to include an upper member or pins  212 - 1  and a lower member or pins  212 - 2 . Moreover, it is seen that these members may be recessed, that is, the pins are generally within the side wall profile of the bucket  102  as best seen in  FIG. 1A . Further, it is seen with respect to  FIGS. 1 and 1A  that the quick couple receptor  212  is protected by a pair of laterally spaced receptor cavity side plates or recessed ears  214  and receptor cavity bottom plates  216 . The use of recessed members,  212 - 1  and  212 - 2 , help ensure, when the members are coupled to the quick connector (see  FIG. 2A ) that the manufacturer&#39;s suggested bucket curl radius is restored. In an alternate preferred embodiment (see  FIGS. 1C-1F ), the upper and lower members may be mounted generally outside the profile of the bucket. The upper and lower members may be chrome and help eliminate the loss of some of the breakout force as would occur with typical excavated buckets. Also, in another embodiment, one of the pins, for example, upper member  212 - 1 , may be recessed and the lower member or pin  212 - 2  may be external. 
         [0040]    With reference to  FIGS. 1 and 1A , it is seen that Applicant&#39;s prehensile bucket  100  is comprised of a single unit incorporating the bucket  102 , the thumb  104 , attached to the pivot point  110 , the pivot point integral with the bucket, with the hydraulic cylinders  402 - 1  and  402 - 2 , which drive the thumb pivotally with respect to the bucket, also attached to the bucket at one end and the thumb at the other end. With such structure, one need only engage the quick couple connector  218  (see  FIG. 2A ) of the stick to the quick connector couple receptor  212  and the hydraulic subsystem  106  to the auxiliary hydraulic system of the excavator. One such line of quick couplers is manufactured by Miller. Quick couplers are known in the art. 
         [0041]    As best seen in  FIG. 1B , an embodiment of Applicant&#39;s novel prehensile bucket includes a thumb  104  whose tines  302  run the full width of the bucket mouth. That is to say, tines  302  mesh between all the spaces or interteeth gaps between teeth  112 , such that there is typically one less tine than there are teeth. For example, in  FIG. 1B , there are five teeth and four tines, the tines form a full length thumb  104  covering all of the inter-teeth spaces in meshing relation (see also  FIG. 1A ). In an alternate preferred embodiment, thumb may define a width which leaves some inter teeth gaps open, for one example, the outermost inter-teeth gap on either side of the bucket mouth. In one such embodiment, in  FIG. 1B , there would only be a pair of tines, the pair connected by the lead line between the reference numeral and the element  318 . 
         [0042]    The assembly of the thumb as best seen in  FIG. 3  includes a multiplicity of typically cylindrical torque tubes, here, three torque tubes designated  304 - 1 ,  304 - 2  and  304 - 3 . They are seen to trend generally transverse to tines  302  through openings in the tines and may be welded to the tines as well as the pivot arm plates (here, torque tubes  304 - 1  and  304 - 2 ) to help strengthen the thumb. They will also help prevent twisting of the thumb as when one or two tines or an outboard tine grabs an item and the remaining tines are unloaded. Furthermore, in the embodiment illustrated in  FIG. 3 , it is seen that a pair of plates  308 - 1  and  308 - 2  are provided with spacers  314  and pivot arm bosses  316 . Alternately, a single plate may be provided on either side rather than a pair of pivot arm plates  308 - 1  and  308 - 2 . The removed ends of tines may define a tine tip  319 . Moreover, while three torque tubes are illustrated in  FIG. 3 , in an alternate preferred embodiment, a different number of torque tubes may be used, in two embodiments either two or four may be provided. Further, with respect to  FIG. 3 , it is seen that the tines may include serrated edges which face the bucket and are generally opposed to the side cutters  208  as seen in  FIG. 2 . 
         [0043]      FIG. 2B  shows that tines  302  may include tine teeth  303  at tine tips  319 . Tine teeth  303  may be welded to tine tips or attached by conventional means, such as bolting. 
         [0044]    As seen with reference to  FIGS. 1 ,  1 A,  3 , and  4 , it may be seen that there are six rotating pivot points on Applicant&#39;s novel device, three per side. Pivot point  110  pivots the claw or thumb about the bucket. A second pivot point  109  pivots the forward end of cylinders  402  with respect to the thumb. Third pivot point at PV pivots the rear of the hydraulic cylinders with respect to the bucket. It is seen that for the three pivot points on each side, six total, each of the six pivots on fixed pins  321 , which pins are removably retained on pin retainers  320  as best seen in  FIG. 4 . 
         [0045]      FIGS. 1A and 1B  illustrate Applicant&#39;s thumb applied to buckets having recessed ears or receptor cavity side plates  214 . The recessed ears typically have fixed pins or members  212 - 1  and  212 - 2  and these buckets are known in the prior art, for engaging with quick coupler devices known in the art. 
         [0046]      FIGS. 1C-1F  illustrate Applicant&#39;s novel thumb and bucket combination used with external ears. Buckets with external ears  217 - 1  and  217 - 2  typically are provided with removable pins or members  212 - 1  and  212 - 2  (for engaging retaining collars) and may be used with a quick coupler or with a regular hookup (non-quick coupler). Quick couplers are also known as “pin grabber” couplers. 
         [0047]    It is seen with respect to  FIGS. 1C and 1D  that the general arrangement of the engagement of the claw or thumb and the ears is the same as that set forth with the recessed ears. However, it may be seen that the ears or plates for mounting the thumb to the bucket are typically adjacent the upper removable pin of the external ears. The upper pin member  212 - 1  and/or lower pin member  212 - 2 , when mounted on the external ears (as in  FIGS. 1C-1F ) may be typically removable, using retainer collars and fasteners on the outboard walls of the external ears. 
         [0048]    Turning now to  FIGS. 1 ,  1 F, and  5 , it is seen that a bent plate cover  408  may be provided for protection of at least some of the hydraulic hoses  502  comprising hydraulic subsystem  106  that are used to drive cylinders  402 - 1  and  402 - 2 . More specifically, it is seen that bent plate cover  408  may be mounted transversely to the bucket typically below where cylinders join to bucket (see  FIG. 1A ). It is also seen that fasteners (not shown) may engage hydraulic hose retaining blocks  504 , here three, which are cup-shaped and can retain in the cups thereof at least some of the hydraulic hoses as seen in  FIG. 5 . Blocks  504  can be welded to the bucket and threaded to receive fasteners. Fasteners (not shown) would thread into the retaining blocks and hold the bent plate cover  408  thereto. Bent plate cover  408  may be bent on the upper and lower edges as shown to help protect the hoses or it may be flat. 
         [0049]      FIG. 3  discloses further details of Applicant&#39;s novel wear pad  340 , which may be made of durable plastic (such as Acetal). The wear pad is typically provided transverse to thumb  104  and positioned at a point where the thumb, when extended, may come into contact with the stick of the excavator. Here, such a location is seen to be on torque tube  304 - 1 . Wear pad  340  may be mounted to a pair of fasteners projecting from a torque tube and a pair of angle iron brackets  342  adjacent the upper and lower borders of the wear pad. The angle iron would typically be welded to the torque tube so that the wear pad can be replaced by removing bolts (not shown) at the end of the fasteners. Typically the wear pad would be mounted to the torque tube or other thumb member at an angle such that its upper face would strike the stick square so that it is flush with the stick. For different excavators, these angles are different, but could be readily determined by one of ordinary skill in the art. Wear pad  340  may come in a variety of widths to match up to the stick. Wear pad  340  is typically wider than the stick and may be in the range of 8 to 30 inches. 
         [0050]      FIG. 3  also illustrates the use of multiple torque tubes to brace the tines, which torque tubes are spaced apart from spaced apart tines, forming a grid-like pattern. This avoids blindspots that would otherwise occur if thumb  104  as in an optional embodiment had plate-like or solid covers. The tines may be laterally spaced apart by a lateral spacing member, which may or may not be torque tubes and may be one or more tabular sheets. 
         [0051]      FIGS. 1B and 1E  illustrate the use of Applicant&#39;s novel thumb  104  with respect to a skeleton bucket, as compared to a solid bucket as seen in the other embodiments. It is seen that a tine is a member that extends at least partially across the mouth of the bucket and generally perpendicular to the bottom front edge of the bucket. The near ends of the tine may or may not couple to the bucket. Typically, the outermost pair of tines may pivotally engage the bucket, but other pairs other than the outermost pair may engage the bucket. Nor does the tine pair pivotally engaging the bucket have to be the same pair that pivotally engages the cylinders. Each tine may be a single piece or constructed of several pieces. Each tine may extend all or part way across the mouth. 
         [0052]    While the invention has been described in connection with one or more preferred embodiments, it is not intended to limit the invention to the particular forms set forth, but on the contrary it is intended to cover such alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.