Abstract:
A tong device for lifting various types and sizes of objects is disclosed. The tong lifting device includes tongs pivotally mounted on a slide rod which is extendable from a lift sleeve. Each tong has an attachment engaging end and an arm extending away from the attachment engaging end. Linkages are pivotally attached to the arms of the tongs, and are pivotally attached to a sliding lobe which travels along the length of the lift sleeve. The design of the lifting device provides a self-opening mode of operation and can be reconfigured in the field for optimum performance.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/661,164 filed Mar. 11, 2005, which is incorporated herein by reference. 

   FIELD OF THE INVENTION 
   The present invention provides a device for lifting a variety of objects, and more particularly relates to a self-opening scissor tong lifting device. 
   BACKGROUND INFORMATION 
   Various types of lifting devices are used for lifting objects such as logs, pipes, debris, concrete highway barriers, rocks and the like. For example, U.S. Pat. No. 6,012,752 to Douglas describes a concrete pipe lifting apparatus with a lockable and releasable scissor grip structure. U.S. Pat. No. 6,331,025 to Douglas describes a barrier lifter apparatus having a scissor structure with L-shaped clamping elements. 
   SUMMARY OF THE INVENTION 
   The present invention provides a tong device for lifting various types and sizes of objects. The tong lifting device includes tongs pivotally mounted on a slide rod which is extendable from a lift sleeve. Each tong has an attachment engaging end and an arm extending away from the attachment engaging end. Linkages are pivotally attached to the arms of the tongs, and are pivotally attached to a sliding lobe which travels along the length of the lift sleeve. The design of the lifting device provides a self-opening mode of operation and can be reconfigured in the field for optimum performance. 
   An aspect of the present invention is to provide a tong lifting device comprising: a lift sleeve; a slide rod extendable from the lift sleeve; at least two tongs pivotally mounted on the slide rod, each tong having an attachment end structured and arranged for mounting an attachment thereto and an arm extending away from the attachment end; a sliding lobe assembly slidably mounted on the lift sleeve; and at least two linkages pivotally connected to the sliding lobe assembly, each linkage pivotally connected to the arm of one of the tongs. 
   Another aspect of the present invention is to provide an assembly including the above-noted tong lifting device and an attachment mounted thereon. 
   A further aspect of the present invention is to provide attachments for mounting on the above-noted tong lifting device. 
   These and other aspects of the present invention will be more apparent from the following description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an isometric view of a tong lifting assembly in accordance with an embodiment of the present invention. 
       FIG. 2  is a front view of the tong lifting assembly of  FIG. 1 . 
       FIG. 3  is a side view of the tong lifting assembly of  FIG. 1 . 
       FIG. 4  is an exploded isometric view illustrating the components of the tong lifting assembly of  FIG. 1 . 
       FIG. 5  is an isometric view of a tong lifting assembly similar to the device shown in  FIGS. 1-4  with a load engaging attachment having toothed claws mounted on the assembly in accordance with an embodiment of the present invention. 
       FIG. 6  is an isometric view of the toothed claw attachment of  FIG. 5 . 
       FIGS. 7-10  are side views illustrating operation of the tong lifting assembly and attachment of  FIG. 5 . 
       FIG. 11  is an isometric view of a tong lifting assembly and a bucket attachment in accordance with another embodiment of the present invention. 
       FIG. 12  is an isometric view of the bucket attachment of  FIG. 11 . 
       FIG. 13  is an isometric view of a tong lifting assembly and a large pipe lifting attachment in accordance with a further embodiment of the present invention. 
       FIG. 14  is an isometric view of the pipe lifting attachment of  FIG. 13 . 
       FIG. 15  is an isometric view of a tong lifting assembly and a smaller pipe lifting attachment in accordance with another embodiment of the present invention. 
       FIG. 16  is an isometric view of the pipe lifting attachment of  FIG. 15 . 
       FIG. 17  is an isometric view of a tong lifting assembly and a clamp attachment in accordance with a further embodiment of the present invention. 
       FIG. 18  is an isometric view of a clamp attachment similar to that shown in  FIG. 17  with the addition of a center linkage which separates the pivot points for the tong arms. 
       FIG. 19  is an isometric view of a tong lifting assembly and a clamp attachment in accordance with another embodiment of the present invention. 
       FIG. 20  is an isometric view of the clamp attachment of  FIG. 19 . 
       FIG. 21  is an isometric view of a tong lifting assembly and a spiked claw attachment in accordance with a further embodiment of the present invention. 
       FIG. 22  is an isometric view of the spiked claw attachment of  FIG. 21 . 
       FIG. 23  is an isometric view of a tong lifting assembly and a vertical pipe lifting attachment in accordance with another embodiment of the present invention. 
       FIG. 24  is an isometric view of the vertical pipe lifting attachment of  FIG. 23 . 
       FIG. 25  is an isometric view of a tong lifting assembly and a rotatable claw attachment in accordance with a further embodiment of the present invention. 
       FIG. 26  is an isometric view of the rotatable claw attachment of  FIG. 25 . 
   

   DETAILED DESCRIPTION 
     FIGS. 1-4  illustrate a tong lifting device  10  in accordance with an embodiment of the present invention. The device  10  includes a lift sleeve  12  with a hook  14  mounted at the upper end thereof by a bolt  15 . During operation, the device  10  is suspended by the hook  14 . A latch assembly  16  having a retractable and rotatable latch  17  is mounted inside the lift sleeve  12  by means of mounting holes  18  located at various positions along the length of the lift sleeve  12 . Lift blocks  19  are provided near the lower end of the lift sleeve  12  on opposing sides thereof. As more fully described below, the lift blocks  19  contact a sliding lobe of the tong lifting device  10  during its operation. 
   A slide rod  20  is slidably received within the lift sleeve  12  and can be extended or retracted in relation to the lift sleeve  12 . A keeper  22  having a channel  23  is mounted at the top end of the slide rod  20 . As more fully described below, the channel  23  has a generally T-shaped cross section for receiving and retaining the latch  17  during operation of the device  10 . Stop members  24  are provided near the bottom end of the slide rod  20  in order to contact the bottom end of the lift sleeve  12  during operation of the device  10 , as more fully described below. As shown most clearly in  FIG. 4 , a tong pivot hole  26  extends transversely through the bottom of the slide rod  20 . The tong pivot hole  26  extends through square pivot blocks  27  which are raised from the side surfaces of the slide rod  20 . 
   The tong lifting device  10  includes a tong assembly  30  comprising a pair of tongs  32   a  and  32   b . Pivot holes  33   a  and  33   b  are provided through the tongs  32   a  and  32   b , respectively. In the embodiment shown in  FIGS. 1-4 , a central tong pivot pin  34  is inserted through the tong pivot holes  33   a  and  33   b , and through the tong pivot hole  26  of the slide rod  20  for pivotal attachment of the tongs  32   a  and  32   b  on the slide rod  20 . Alternatively, an additional center link mounted on the square pivot blocks  27  of the slide rod  20  may be used instead of the central tong pivot pin  34 , as discussed in more detail below. 
   The tong  32   a  has an attachment end  36   a  and an attachment mounting hole  37   a  at one end thereof, and a linkage pin hole  38   a  and a linkage sleeve  39   a  at the other end thereof. Similarly, the tong  32   b  has an attachment end  36   b  and an attachment mounting hole  37   b  at one end thereof, and a linkage pin hole  38   b  and a linkage sleeve  39   b  at the other end thereof. The attachment end  36   a  and  36   b  of each tong  32   a  and  32   b  includes a tab or key projection, as well as a recess formed in a raised portion of the tong which is spaced from the tab. As more fully described below, this tab and recess arrangement helps secure various attachments to the tongs  32   a  and  32   b.    
   The tong lifting device  10  also includes a sliding lobe assembly  40  comprising opposing lobe plates  42   a  and  42   b  which are spaced apart and secured to each other by bolts  44 . The sliding lobe assembly  40  is movable along the length of the lift sleeve  12 , with the lift blocks  19  at the bottom of the lift sleeve  12  engaging the lobe assembly  40  and preventing it from sliding off the bottom end of the lift sleeve  12 . Linkage pivot holes  46   a  and  46   b  are provided through the lobe plates  42   a  and  42   b  of the lobe assembly  40 . Sleeves  47   a  and  47   b  extend between the lobe plates  42   a  and  42   b  at the locations of the linkage pivot holes  46   a  and  46   b , respectively. 
   The tong lifting device  10  also includes a linkage assembly  50  comprising linkages  52   a  and  52   b . The linkage  52   a  includes a lobe pivot hole  53   a  receiving a pivot pin  54   a  at one end thereof, and a tong pivot hole  55   a  receiving a pivot pin  56   a  at the other end thereof. The linkage sleeve  39   a  is aligned with the tong pivot hole  55   a . Similarly, the linkage  52   b  includes a lobe pivot hole  53   b  receiving a pivot pin  54   b  at one end thereof, and a tong pivot hole  55   b  receiving a pivot pin  56   b  at the other end thereof. The linkage sleeve  39   b  is aligned with the tong pivot hole  55   b . Each linkage  52   a  and  52   b  is thus pivotally mounted on the sliding lobe assembly  40  and pivotally mounted on the end of a tong arm  35   a  and  35   b , respectively. 
     FIG. 5  is an isometric view of a tong lifting assembly  10  similar to that shown in  FIGS. 1-4 , with a toothed claw attachment  60  mounted thereon.  FIG. 6  is an isometric view of the toothed claw attachment  60  without the tong lifting assembly. The attachment  60  includes multiple toothed claws  62  which are configured to lift various objects such as logs, debris and the like. The attachment  60  includes mounting ends  64  which have a tab as well as a recess formed in a raised portion of the mounting end spaced from the tab. This arrangement is complimentary to the tab and recess arrangement provided at the attachment ends  36   a  and  36   b  of the tongs  32   a  and  32   b . A mounting bolt  66  is inserted through mounting holes  68  which extend through the mounting ends  64  of the attachment  60 . The mounting bolts  66  are also inserted through the mounting holes  37   a  and  37   b  of the tongs  32   a  and  32   b  in order to secure the toothed claw attachment  60  to the tong lifting device  10 . 
   The various components of the tong lifting assembly  10 , and the attachments mounted thereon, are made from standard materials such as steel or any other suitable materials known to those skilled in the art. 
     FIGS. 7-10  illustrate operation of a tong lifting assembly  10  and toothed claw attachment  60  similar to that shown in  FIG. 5 . In  FIG. 7 , the toothed claws  62  of the attachment  60  are in an open position while the device  10  is being lowered toward an object to be lifted  69 . During this stage, the outer lift sleeve  12  and the inner slide rod  20  travel downward together, and the latch  17  is secured in the channel  23  of the keeper  22 . 
   In  FIG. 8 , the latch  17  has been released from the keeper  22 , thereby allowing relative movement between the lift sleeve  12  and the slide rod  20  as the hook  14  is pulled upward. The upward movement of the lift sleeve  12  pulls the sliding lobe assembly  40  upward due to contact with the lift blocks  19  at the bottom of the lift sleeve  12 . The upward movement of the sliding lobe assembly  40  draws the toothed claws  62  of the attachment  60  together by means of the linkages  52   a  and  52   b , and the pivotal mounting of the tongs  32   a  and  32   b  on the central pivot pin  34  at the bottom of the slide rod  20 . 
   In  FIG. 9 , the object  69  is lowered to a resting place and the lift sleeve  12  moves downward to receive the slide rod  20  as the hook  14  is lowered. This relative downward movement of the lift sleeve  12  in relation to the slide rod  20  causes the latch  17  to contact the keeper  22  at the top of the slide rod  20 . After contact between the latch  17  and keeper  22  is made, further downward movement of the lift sleeve  12  causes the latch  17  to retract toward the latch assembly  16 , which causes a 45 degree rotation of the latch  17 . Subsequent upward movement of the lift sleeve  12  and latch assembly  16  as shown in  FIG. 10  causes another 45 degree rotation of the latch  17  to the position shown in  FIG. 10  in which the latch  17  is secured within the channel  23  of the keeper  22 . The latch assembly  16  thus produces 90° of rotation with each up and down cycle, to thereby rotate the latch  17  alternatively between engaging and disengaging positions with respect to the keeper  22 . 
   As shown in  FIG. 10 , with the latch  17  secured in the keeper  22 , upward movement of the lift sleeve  12  and slide rod  20  results in lowering of the sliding lobe assembly due to the weight of the components, and opening of the toothed claw attachment  60  as the tongs  32   a  and  32   b  pivot around the center tong pivot pin  34 . 
   When tension is taken off the lift hook  14 , the lift sleeve  12  is allowed to slide down through the slide lobe  40  until the latch  17  engages the keeper  22  on the slide rod  20 . When tension is reapplied through the hook  14 , the lift sleeve  12  and slide rod  20  are coupled together, but the upward tension no longer produces a gripping force on the object  69 . 
     FIGS. 11 and 12  illustrate a tong lifting assembly  10  and a bucket attachment  70  in accordance with another embodiment of the present invention. The bucket attachment  70  includes two opposing buckets  72  mounted by tabbed mounting ends  74  on the tong assembly  30 . Mounting bolts  76  are inserted through mounting holes  78  near the mounting ends  74 . The mounting bolts  76  also extend through the tong mounting holes  37   a  and  37   b  to secure the bucket  72  to the tongs  32   a  and  32   b.    
     FIGS. 13 and 14  illustrate a tong lifting assembly  10  and a relatively large pipe lifting attachment  80  in accordance with a further embodiment of the present invention. The large pipe lifting attachment  80  includes curved clamps  82  and tabbed mounting ends  84 . In this embodiment, a center link  85  is used in place of the center tong pivot pin  34  of the previous embodiments. The center link  85  includes square openings  86  which receive the square projections  27  at the bottom of the slide rod  20 , which are shown most clearly in  FIG. 4 . The center link  85  includes tong pivot holes  87   a  and  87   b . A sleeve  89   a  is aligned with the pivot hole  87   a , while a sleeve  89   b  is aligned with the tong pivot holes  87   b . Tong pivot pins  88   a  and  88   b  extend through the tong pivot holes  87   a  and  87   b , respectively, and also extend through the attachment mounting holes  37   a  and  37   b  of the tongs  32   a  and  32   b . The use of the center link  85  allows a larger gripping ratio with a smaller travel distance for the clamps  82 . 
     FIGS. 15 and 16  illustrate a tong lifting assembly  10  and a relatively small pipe lifting attachment  90  in accordance with another embodiment of the present invention. The small pipe lifting attachment  90  includes curved clamps  92  and tabbed mounting ends  94 . Mounting bolts  96  are inserted through holes  98  near the mounting ends  94 . The mounting bolts  96  also extend through the mounting holes  37   a  and  37   b  of the tongs  32   a  and  32   b.    
     FIG. 17  illustrates a tong lifting assembly  10  and a clamp attachment  100  in accordance with a further embodiment of the present invention. The clamp attachment  100  includes clamps  102  and tabbed mounting ends  104 . Mounting bolts  106  extend through holes near the mounting ends  104 . The mounting bolts  106  also extend through the mounting holes  37   a  and  37   b  of the tongs  32   a  and  32   b.    
     FIG. 18  illustrates a clamp attachment  110  similar to that shown in  17 , except the central tong pivot pin  34  is replaced with a center link  105 . Square openings  107  in the center link  105  receive the square projections  27  at the bottom of the slide rod  20 . Tong pivot holes  108   a  and  108   b  are provided at opposite ends of the center link  105  for attachment to the mounting holes  37   a  and  37   b  of the tongs  32   a  and  32   b.    
     FIGS. 19 and 20  illustrate a tong lifting assembly  10  and a clamp attachment  120  in accordance with another embodiment of the present invention. The clamp attachment  120  includes clamps  122  with tabbed mounting ends  124 . Mounting bolts  126  extend through mounting holes  128  near the mounting ends  124 . The mounting bolts  126  also extend through the mounting holes  37   a  and  38   b  of the tongs  32   a  and  32   b.    
     FIGS. 21 and 22  illustrate a tong lifting assembly  10  and a spiked claw attachment  130  in accordance with a further embodiment of the present invention. The spiked claw attachment  130  includes spiked claws  132  and tabbed mounting ends  134 . Mounting bolts  136  extend through mounting holes  138  in the mounting ends  134 . The mounting bolts  136  also extend through the mounting holes  37   a  and  37   b  of the tongs  32   a  and  32   b.    
     FIGS. 23 and 24  illustrate a tong lifting assembly  10  and a vertical pipe lifting attachment  140  in accordance with another embodiment of the present invention. The vertical pipe lifting attachment  140  includes claws  142  and tabbed mounting ends  144 . Mounting bolts  146  extend through mounting holes  148  near the mounting ends  144 . The mounting bolts  146  also extend through the mounting holes  37   a  and  37   b  of the tongs  32   a  and  32   b.    
     FIGS. 25 and 26  illustrate a tong lifting assembly  10  and a rotatable claw attachment  150  in accordance with a further embodiment of the present invention. A rotatable claw attachment  150  includes rotatable claws  152  and tabbed mounting ends  154 . Mounting bolts  156  extend through mounting holes  158  near the mounting ends  154 . The mounting bolts  156  also extend through the mounting holes  37   a  and  37   b  of the tongs  32   a  and  32   b.    
   In accordance with an embodiment of the present invention, with the addition of a center link added with certain attachments, the main tong pivot  34  is removed and the tongs  32   a  and  32   b  are pinned through the holes  37   a  and  37   b  used to fix the attachment to the tongs. An example of the use of a center link  85  is shown in  FIGS. 13 and 14 . Another example of the use of a center link  105  is shown in  FIG. 18 . The center link is placed inboard of the tongs on each side. This allows a greater gripping ratio at the expense of attachment travel. The keyed pattern  36   a  and  36   b  incorporated into the profile of the tongs  32   a  and  32   b , and the tabs provided at the mounting ends of the attachment provides the transfer of force from the tongs to the attachments. 
   The tong lifting assembly of the present invention provides several advantages. The design allows for a self opening mode of lifter not present in existing designs. The sliding assembly provides the ability to latch the lifter in the open or release mode when the motion of the tines or other components of the attachment is restricted by the ground or adjacent objects. A mechanism by which to latch and unlatch the lifter cyclically is provided. The design allows multiple points of attachment of the latch assembly along the length of the lift sleeve to provide the ability to fix the open mode of the lifter to a given width for working in confined spaces. The design also allows the main points of geometry of the tongs to be field re-configured in order to accommodate loads of various profiles or shapes. The present device also allows field removal and replacement of a variety of load engaging tools to accommodate loads of various profiles or shape. 
   Whereas particular embodiments of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims.