Abstract:
A clamping assembly is disclosed including a plurality of tines each pivotally coupled to a spreader having first ends above the spreader and second ends below the spreader. The first ends are coupled to lines joined at a common coupler and the second ends include hooked portions. The tines may have a planar shape and fit within radial slots defined by the spreader. The second ends may include slanted lower surfaces that slope upward with distance inward toward a center of the clamping assembly. In use the tines are lowered over an object. Tension applied to the lines causes pivoting of the tines effective to exert a clamping force on the object.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to material handling devices and, more specifically, to a mechanical pinch clamping assembly. 
       BACKGROUND OF THE INVENTION 
       [0002]    Moving large objects such as rocks for use in a rock wall frequently requires handling devices such as grappler assemblies. Often a hydraulic thumb can be used with a fork or lift to capture the object to be moved. In lieu of the thumb attachment a piece of chain or similar material is used to wrap around the object to be moved, which is time consuming. This also poses a safety issue because the chain tends to slip as a person tries to pick up the rock, together with the fact that you may have to take many attempts to get the chain to actually grip the rock. 
       SUMMARY OF THE INVENTION 
       [0003]    In one aspect of the invention, an apparatus for lifting objects includes two or more tines each having first and second ends. The first ends define an attachment point and the second ends define hooked portions. The two or more tines pivotally secure to a spreader between the first and second ends thereof. 
         [0004]    In another aspect of the invention, the spreader defines at least two slots each sized to receive one of the two or more tines, the slots extend radially outward from a common point and are uniformly and circumferentially distributed about the common point and radially offset from the common point by a same distance. The two or more tines may have an oblong cross section at a point of attachment to the spreader such that the two or more tines each have a longer dimension of the oblong cross section thereof aligned with a longer dimension of a slot. In another aspect, the two or more tines are pivotally secured to the spreader by pins each spanning at slot of the at least two slots and passing through a tine of the at least two tines. 
         [0005]    In another aspect, at least two chain portions each secured at a first end thereof to the attachment point of one of the tines of the two or more tines, the at least two chains being secured to one another at second ends thereof. The two or more tines may include an inner surface facing the spreader, the attachment point and hooked portion both protruding inwardly toward the spreader from the inner surface. The attachment point may protrude inwardly toward the spreader from the inner surface a greater extent then the hooked portion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    Preferred and alternative examples of the present invention are described in detail below with reference to the following drawings: 
           [0007]      FIG. 1  is an isometric view of a clamping assembly in accordance with an embodiment of the invention. 
           [0008]      FIG. 2  is a top plan view of a spreader in accordance with an embodiment of the invention. 
           [0009]      FIGS. 3A and 3B  illustrate a tine in accordance with an embodiment of the invention. 
           [0010]      FIGS. 4A through 4C  are side views showing use of the clamping assembly in accordance with an embodiment of the invention. 
           [0011]      FIG. 5  illustrates a clamping assembly coupled to a hydraulically actuated shovel of a tracked vehicle in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0012]    Referring to  FIG. 1 , a clamping assembly  10  may include two or more, preferably three, tines  12  each mounted to a spreader  14 . The spreader  14  may include two or more slots  16 , preferably three, radiating outwardly from a common center. The tines  12  may each be inserted within one of the slots  16  and pinned in the slot  16  by means of pins  18 . The pins  18  may be bolts or other fasteners passing through both the slots  16  and tines  12  positioned therein. The tines  12  are coupled to one or more lines  20  above the spreader  14 . In the illustrated embodiment, the lines  20  are chains and may be coupled to the pins  18  by means of shackles or other linking structure. However, the lines  20  may be cables, ropes, or other type of line capable of supporting the loads for a given application. In the illustrated embodiments, the lines  20  secure to a common coupler  22 , such as by securing a link of each chain  20  to a common ring, or separate rings, mounted to a common coupler  22 . The coupler  22  may be mounted to another line, such as a chain, that is mounted to a device for raising and lowering the clamping assembly  10 . In some embodiments, the coupler  22  may incorporate a swivel that allows for rotation of the clamping assembly  10 . For example, the coupler  22  or a line to which it is coupled may be coupled to hydraulically actuated arm of a front loader, back hoe, or other machinery either directly or by mounting to a shovel mounted to such an arm. The tines  12 , spreader  14 , chains  20 , and other components of the clamping assembly  10  may be made of any suitable material for the loads of a given application. In some embodiment, some or all of the components of the clamping assembly  10  are formed of mile steel plate for ease of manufacturing. 
         [0013]    Referring to  FIG. 2 , as noted above the slots  16  extend outwardly from a common center. In particular, each slot  16  may be offset from the common center by a distance  24  and have an extent  26  outward from the offset distance  24 . As is readily apparent, the extent  24  is many times larger, e.g. between 10 and 20 times larger, than the width of the slots  16 , e.g. a width tangential to a circle around the common center. Apertures  28  for receiving the pins  18  may pass through the spreader  14  in the vicinity of each slot  16 . In particular, apertures  28  may pass through the spreader perpendicular to the slots such that portions of each aperture are positioned on either side of a slot  16 . For example, apertures may extend through the spreader  14  in a tangential direction to a ring about the common center. 
         [0014]    In some embodiments, cutouts  30 , such as arcuate cutouts  30 , defined in the spreader  14  and positioned between slots  16  may leave prongs or strips of material on either side of the slots  16  and reduce the amount of material required to form the spreader  14 . Alternatively, in some embodiments, the spreader  14  may have a generally circular shape having the slots  16  defined therein and the cutouts  30  may be omitted. 
         [0015]    Referring to  FIGS. 3A and 3B , a tine  12  may be understood with respect to a vertical direction  32  and a horizontal direction  34  that correspond generally to the horizontal and vertical directions of the clamping assembly  10  in use, though variation from an absolute horizontal and vertical direction may occur. The tine  12  may define an aperture  36 , or other attachment structure such as a slot or hook, for securing to a line  20 . The tine  12  may also define an aperture  38  for receiving a pin  18  securing the tine  12  to the spreader  14 . A hooked portion  40  of the tine  12  is used to engage and lift objects. In the illustrated embodiment, the end of the spreader  14  is closer to the aperture  36  than to the end of the hooked portion  40 . For example, along a vertical separation between the aperture  36  and the end of the hooked portion  40  may be more than two times, preferably more than four times, and more preferably eight times, a vertical separation between apertures  36  and  38 . An inner surface  42  of the tine may extend along the vertical direction  32  between the hooked portion  40  and the apertures  36 ,  38 . In some embodiments, the vertical direction  32  may be defined as being parallel to the inner surface  42 . In other embodiments, the inner surface may be curved, angled, or have some other shape. Stated differently, the apertures  36 ,  38  and the distal end of the hooked portion  40  like along a concave curve that faces inwardly toward the other tines  12 , i.e. the common center of the spreader  14 . In this manner, pivoting due to an upward force on the aperture  36  may pivot the hooked portion  40  inward and provide a surface positioned under an object to facilitate lifting. 
         [0016]    The aperture  36  may be located closest to a common center of the spreader  14  along the horizontal direction  34 . The aperture  38  may be spaced outwardly from the aperture  36  (e.g. away from the common center) by a distance  44  and the end of the hooked portion  40  may be spaced inwardly (closer to the common center) from the aperture  38  by a distance  46 . The distance  46  may be less than the distance  44 , e.g. between 90 and 60 percent of the distance  44 . 
         [0017]    As is apparent in  FIG. 3A , the hooked portion  40  may include a curved surface that transitions from a vertical direction aligned with the inner surface  42  to a horizontal portion perpendicular to the inner surface  42 . The transition may be a circular arc or some other smooth surface or may be a simple angled junction. Although the distal end of the hooked portion  40  has a planar upper surface as shown in  FIG. 3A , in other embodiments it may angle upward or downward relative to the horizontal direction  34 . 
         [0018]    In some embodiments, the hooked portion  40  may include a slanted, sloped, or contoured lower surface  48  that facilitates guidance of objects into a volume between the two or more tines  12 . In particular, the lower surface  48  may slope upward with distance along the horizontal direction  34  away from the inner surface  42 . The slope may be constant or non-constant, e.g. the slope may increase with distance from the inner surface  42 . 
         [0019]    Referring specifically to  FIG. 3B , the tines  12  may advantageously have a planar shape such that the width  50  thereof is much greater than the thickness  52  thereof. In this manner, the tines  12  may fit within the narrow slots  16  of the spreader  14 . For example, the width  50  may be between 4 and 8 times the thickness  52 . In the illustrated embodiment, the width  50  of the tine  12  is substantially constant along the length thereof other than rounding at an upper end and narrowing of the hooked portion  40  due to the sloped lower surface  48 . However, variable width and/or thickness may also be used. 
         [0020]    Referring to  FIG. 4A , in preparation for use, the tines  12  may be suspended from the lines  20  in the illustrated configuration. The tines  12  may have a resting orientation in the absence of a load positioned between them. The tines  12  may be symmetrical about a common axis  54  that may also correspond to the common central point of the spreader  14  mentioned above. Accordingly, the other tines may behave in the same manner as the tine  12  illustrated in  FIGS. 4A-4C . 
         [0021]    Referring to  FIG. 4B , an object  56  may be positioned between the tines  12  by lowering the tines  12  over the object  56 . The sloped lower surface  48  may advantageously guide and urge the lower ends of the tines  12  around the object  56 . Referring to  FIG. 4C , upon lifting up on the lines  20 , tension  58  on the lines  20  creates a moment  60  about the pin  18 . Due to the outward force  62  of the spreader  14 , the hooked portion  40  of the tine  12  is constrained to exert an inward force  64  on the object  56 . The combined inward forces of the tines  12  retain the object  56  during subsequent lifting and transportation of the object  56 . The inward force  64  is dependent on the tension  58 , which is dependent on the weight of the object  56  being lifted. Accordingly, the inward force  64  increases with the weight of the object thereby applying an appropriate clamping force. Upon deposition, the tines  12  may be disengaged by lowering the clamping assembly  10  and moving the clamping assembly  10  laterally without lifting such that clamping force does not prevent the object from moving out from among the tines  12 . 
         [0022]    Referring to  FIG. 5 , as noted above, the lines  20  and common coupler  22  may be coupled to a shovel  70  of a tracked vehicle  72 . For example, the shovel  70  may be mounted to hydraulic actuators  74  either with or without an intervening arm (not shown) that itself may be articulated and hydraulically actuated. Alternatively, the coupler  22  may be connected to a cable or chain connected to a pulley system, driven spool, or other cable actuating mechanism for raising and lowering the clamping assembly  10 . 
         [0023]    While the preferred embodiment of the invention has been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. Spreader bars and tine sizes may be altered to facilitate various sizes of objects to be moved. Load capacity and strength of chains and swivels may be altered based on considerations relative to the size and weight of the anticipated weight of the objects to be moved/lifted. Likewise, the material used to construct the components may vary according to availability, strength and other considerations. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow.