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TECHNICAL FIELD 
       [0001]    This disclosure relates to locking devices for links, particularly for link groups for connecting dangling grapplers to carrier machines and links for multi-processor jawsets. 
       BACKGROUND 
       [0002]    Dangling grapples, like scrap grapples, orange peel grapples, clamshell grapples, logging grapples and the like, may be connected to the stick of material carrier machines, excavators or material handler equipment by link groups, also known in the art as a crossheads. A link group may thus carry the grapple weight and the load generated by the payload. 
         [0003]    Link groups may be provided with a movable main pin extending through parallel bushings to facilitate mounting and dismounting of a grapple from the stick of the material carrier machine. When a grapple is in a rest position, for instance lowered to the ground, the main pin may be removed from the link group, so that the stick of the machine may be detached from the grapple. 
         [0004]    To expedite operations, especially during dismounting procedures, operators may choose not to extract the main pin completely from the link group but only to slide it through the bushings far enough to allow the stick to move away from the link group. However, special care must be taken not to remove the pin completely and further work and caution may be required to avoid inadvertently moving the link group in such a manner to cause the pin to fall out, hence slowing work procedures. 
         [0005]    The same care must be taken when another grappler is connected to the stick of the machine. In this case, operators may insert the main pin back in the link group, carefully check the position of the main pin to verify that the main pin is fully inserted, and lock the main pin into place. 
         [0006]    The above problems may be encountered also in multi-processor devices, which may consist of a standard housing and interchangeable jawsets for different demolition applications. The jawsets may be connected to the standard housing by three large pins: two pins in a static setup and a third pin in a dynamic setup. Each of these pins has to be removed or displaced to change from one jawset to the another and, again, efficiency in the work flow may be negatively affected if the pins are completely removed or fall out and time is consumed in carefully positioning and checking the position of the main pin when the main pin is pushed back into place. 
         [0007]    The present disclosure is directed, at least in part, to improving or overcoming one or more aspects of prior systems. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    In a first aspect, the present disclosure describes a locking device, in particular for a link of a grappler, comprising a movable pin provided with at least one groove, a locking plate to engage the groove and a holding element to hold the locking plate in the groove, wherein the engagement of the locking plate into the groove locks the pin. 
         [0009]    In a second aspect, the disclosure describes a linking device comprising the locking device of the first aspect and a frame including spaced apart bushings to receive the pin. 
         [0010]    In a third aspect, the disclosure describes a method of locking a link, particularly a link of a grappler, comprising the steps of providing a frame having spaced apart bushings, wherein at least one of the bushings carries a locking plate, threading a pin having a groove through the spaced apart bushings and engaging the locking plate into the groove. 
         [0011]    Other features and advantages of the present disclosure will be apparent from the following description of various embodiments, when read together with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is an isometric view of an embodiment of a link for a grappler comprising a locking device according to the present disclosure; 
           [0013]      FIG. 2  is a plan view of a main pin of the link for a grappler of  FIG. 1 ; 
           [0014]      FIG. 3  is a partial cross section view of the link coupled to a stick of a material carrier machine, in which the main pin is in a first locking position and the face of a locking plate is not visible; 
           [0015]      FIG. 4  is a partial cross section view of the link, coupled to the stick of the material carrier machine, in which the main pin is partially inserted and the face of a locking plate is visible; 
           [0016]      FIG. 5  is a partial cross section view of the link in which the main pin is in a second locking position and the face of a locking plate is not visible. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    This disclosure generally relates to locking devices for links of dangling grapples and links of jawsets of multi-processor devices. 
         [0018]      FIG. 1  illustrates an embodiment of a locking device for a link of a grappler (the grappler is not shown in the figures) according to the present disclosure. 
         [0019]    A frame  10  of a link of a grappler may comprise a saddle  12  connected to a pair of arms  14 . The saddle  12  may further comprise a pair of flanges  15 , spaced apart for receiving a coupling portion of the grappler. Each flange  15  may have a guide hole  16 . A grappler may be connected to the frame  10  by aligning the guide holes  16  to a corresponding hole in the coupling portion of the grappler and inserting a connecting pin  18  through the guide holes  16  and the corresponding hole in the grappler. A washer  20  and a nut  22  may be placed onto end of the inserted connecting pin  18  thereby connecting the saddle  12  to the grappler. A cotter  24  may further secure the connecting pin  18  to the saddle  12 . 
         [0020]    Each flange  15  of saddle  12  may further comprise a pair of holes  26  for receiving a lock pin  28 . The lock pin  28  may be secured to the saddle  12  by a pin lock  30 . 
         [0021]    An end of each arm  14  may be connected to the saddle  12 . A side of an arm  14  may face the corresponding side of the other arm  14 . These sides of arms  14  are hereinafter referred to as inner sides  33  and, accordingly, the opposite side of each inner side  33  of an arm  14  is hereinafter referred to as outer side  34 . 
         [0022]    The free end of each arm  14  may carry a bushing  32 . Bushing  32  may extend through arm  14  with openings on inner side  33  and outer side  34  of each arm. Bushings  32  of arms  14  may be substantially aligned. 
         [0023]    On outer side  34  of an arm  14 , a first outer boss  35  may circumvent the opening of the bushing  32 . A second outer boss  36  may circumvent the opening of the bushing  32  on the outer side  34  of the other arm  14 . Inner bosses  38  may be carried on the inner sides  33  around the openings of the bushings thereon. Outer bosses  35 ,  36  and inner bosses  38  may assist in extending the length of bushings  32  such that the openings of bosses  35 ,  36 ,  38  operate as openings of bushings  32 . Adjacent first outer boss  35 , on outer side  34 , may be a threaded bushing  44 . Threaded bushing  44  may be positioned between the first outer boss  35  and the end of arm  14  connected to saddle  12 . 
         [0024]    The first outer boss  35  may comprise a flat surface  40 , an outer curved surface  42  and an inner curved surface  43 . Outer curved surface  42  may include a slot  45 . The opening of slot  45  may face the free end of arm  14  and may partially encircle the outer curved surface  42 . At one end, slot  45  may widen to form a recess  46 . Particularly, recess  46  may be positioned adjacent to said end of slot  45 . Towards the opposite end, beyond recess  46 , slot  45  may extend from the outer curved surface  42  through the first outer boss  35  to form an opening on the inner curved surface  43 . 
         [0025]    aperture  47  and an opening  48  may be located on flat surface  40 . Aperture  47  and an opening  48  may be positioned adjacent to the slot  45 . Aperture  47  may be located close to the end of slot  45  proximal to recess  46 . Particularly, aperture  47  may be located towards the end of slot  45  such that the recess  46  is between aperture  47  and said end. Opening  48  may be located towards the opposite end of slot  45 . Aperture  47  and opening  48  may extend from the flat surface  40  into first outer boss  35  to the cavity of slot  45  such that aperture  47  and opening  48  may be contiguous with slot  45 . 
         [0026]    A locking plate  49  may be provided, having size and shape suitable to fit into slot  45 . In one embodiment, locking plate  49  may have a hemispherical shape with a curved edge  50  and a linear edge  51 . The curvature of curved edge  50  may substantially correspond to the curvature of outer curved surface  42  of the first outer boss  35 , such that at alignment of curved edge  50  with the outer curved surface  42  a substantially plane surface may be formed. At such alignment the linear edge  51  may project through the opening of slot  45  on the inner curved surface  43  of the first outer boss into bushing  32 . 
         [0027]    Locking plate  49  may comprise a face  52 , which may be visible prior to insertion of locking plate  49  into slot  45  and alignment of curved edge  50  with the outer curved surface  42 . On the other hand, at such alignment face  52  may be positioned within first outer boss  35  and may not be visible. Face  52  may thus function as an indicator to denote if the linear edge  51  is projecting into bushing  32 . Face  52  may be visible when linear edge  51  is not projecting into bushing  32  and may not visible when linear edge  51  projects into bushing  32 . 
         [0028]    Face  52  may include a threaded hole  53 . An end of locking plate  49  that may be configured into a rib  54  may be adjacent to threaded hole  53 . Particularly, rib  54  may be formed by slanting of the linear edge on either side of the rib. More particularly, the rib may be chamfered. 
         [0029]    A biasing element  55  may fit into recess  46  and may rest therein. The biasing element  55  may be of any suitable resilient material such as a spring. Rib  54  may abut and compress biasing element  55  upon insertion of locking plate  49  into slot  45 . Biasing element  55  may push on locking plate  49 . Locking plate  49  may be retained in the slot  45  by locking bolt  56 . 
         [0030]    Locking bolt  56  may be connected to locking plate  49  at threaded hole  53  through aligned aperture  47 . In this connection, locking bolt  56  may also function as a pivot to the locking plate  49 . Consequently, pushing action of the biasing element  55  on one end of the locking plate  49  may turn the locking plate  49  about locking bolt  56  to effect movement of the locking plate  49  into slot  45  and to effect projection of linear edge  51  through the opening of the slot  45  on the inner curved surface  43  of the first outer boss into the bushing  32 . Particularly, the biasing element  55  may exert a sufficient force to pivot the locking plate  49  about 15 to 20 degrees. 
         [0031]    A stud  58  may be positioned between the biasing element  55  and the locking plate  49 . Stud  58  may effect an even distribution of the force exerted by the biasing element  55  onto the locking plate  49 . 
         [0032]    A main pin  60  may be provided for insertion through bushings  32  on arms  14 . With reference to  FIG. 2 , main pin  60  may comprise a shank  62 . The shank  62  may comprise a first groove  64  and a second groove  66 . Each groove may include an oblique wall  68  and an upright wall  70 . First groove  64  and the second groove  66  may be symmetrical and may be positioned on the shank  62  in an opposite orientation. Accordingly, the oblique walls  68  of grooves  64 ,  66  may face inwardly, with respect to the shank  62 , towards each other. Upright walls  70  may face the ends of shank  62 . 
         [0033]    With the main pin  60  inserted into bushings  32 , first groove  64  and second groove  66  may operate with the locking plate  49  to control the movement of the main pin  60  through bushings  32 . Each groove  64 ,  66  may engage with locking plate  49  independently. Main pin  60  may be in a first locking position when the locking plate  49  is engaged in the first groove  64  and may be in a second locking position when the locking plate  49  is engaged in the second groove  64 . 
         [0034]    Pushing action of biasing element  55  on one end of the locking plate  49  may turn locking plate  49  about the locking bolt to effect movement of the locking plate into slot  45  and to effect projection of linear edge  51  into the bushing  32 . Consequently, when the main pin  60  is inserted though the bushings  32 , locking plate  49  may engage the shank  62  and the grooves  64 ,  66 . Particularly, locking plate  49  may have a continues pressing engagement with the main pin  60 . Such an engagement may be effected by the force exerted by the biasing element  55  on the locking plate  49 . 
         [0035]    The locking plate  49  may enter or exit either groove  64 ,  66  at the oblique wall  68  by sliding along said wall. Upright wall  70  may serve as an abutment surface to restrict movement of the locking plate out of the groove  64 ,  66  from said wall. 
         [0036]    Main pin  60  may further comprise a locking flange  72  connected to one end of the shank  62 . Locking flange  72  may be shaped as a tear drop and may carry a cavity  74 . Main pin  60  may be fastened to an arm  14  by the locking flange  72 . At complete insertion of the main pin  60  into bushings  32 , the locking flange  72  may abut against first outer boss  35  and the threaded bushing  44  may project into the aligned cavity  74 . A washer  76  and bolt  78  may be used to fasten the locking flange  72  to the arm  14 . The opposite end of shank  62  may be a leading end  80  comprising a rim with a bevelled edge to ease insertion through the bushings  32 . 
         [0037]    Operation of the device according the present disclosure will be now described with reference to  FIGS. 3 through 5 . 
         [0038]    With reference to  FIG. 3 , the main pin  60  may be locked in the first locking position by the locking plate  49  engaging the first groove  64 . Extraction of the main pin  60  out of the bushings  32  and frame  10  may be prevented by the abutment of the locking plate  49  with the upright wall  70  of the first groove  64 . As the locking plate  49  is positioned in first groove  64 , the face  52  of the locking plate  49  is not visible, indicating that the main pin  60  is locked in the first locking position. In this position, a stick  82  of the material carrier machined, having a passage  84 , may be positioned between arms  14  of frame  10 . Passage  84  may be aligned with the bushings  32  and stick  82  may be positioned for coupling with the arms  14 . 
         [0039]    With reference to  FIG. 4 , the leading end  80  may be pushed though the bushing  32  of one arm  14  into passage  84 . As the leading end  80  starts to move, the locking plate  49  may engage and slide along the oblique wall  68  out of first groove  64 . Movement of locking plate  49  along oblique wall  68  and out of first groove  64  may push the locking plate  49  against the exerting force of biasing element  55  thereby turning the locking plate  49  about locking bolt, in the opposite direction, to effect movement of the locking plate  49  through the opening of the slot  45  on the inner curved surface  43  out of bushing  32 . With the locking plate  49  positioned out of first groove  64 , face  52  may be visible indicating that the main pin is not in a locking position. Face  52  may remain visible until the locking plate  49  is in a locking position. 
         [0040]    Main pin  60  may be pushed with sufficient force to overcome the exerting force of the biasing element  55  and to effect movement of the locking plate  49  out of the first groove  64 . If sufficient force is not exerted the locking plate  49  may slide back along oblique wall  68  into first groove  64 . 
         [0041]    The first locking position may be overridden by inserting a rod into opening  48  on flat face  40  of the first outer boss  35 . The locking plate  49  may be held in a disengagement position by the rod thereby allowing the main pin to be completely removed from bushing  32 . In the disengagement position the locking plate  49  may not be in contact with the shank  62 . 
         [0042]    With reference to  FIG. 5 , the main pin  60  may be pushed through passage  84  into bushings  32  of the other arm  14 . The main pin  60  may progress through the bushings  32  till locking plate  49  engages into second groove  66 . Locking plate  49  may slide along oblique wall  68  into second groove  66 . Further movement of the main pin  60  through bushings  32  may be prevented by the abutment of the locking plate  49  with the upright wall  70  of the second groove  66 . With locking plate  49  in second groove  66  the face  52  of the locking plate  49  may not be visible indicating that the main pin  60  may be locked in the second locking position. In the second locking position first groove  64  may be positioned within second outer boss  36 . 
         [0043]    The skilled person will appreciate that the locking device according to the invention may be effected with one groove such that the main pin  60  is secured to arm  14  in the first locking position during mounting or dismounting of a link to a material carrier machine or changing of a grappler. Additionally, correct insertion of main pin  60  may be effected with one groove such that, in operation, the main pin  60  is secured to arm  14  in the second locking position. 
         [0044]    The skilled in the art will also appreciate that holes in the main pin may be used instead of grooves and that locking plates may indicate pins or rods, to be used as indicators and locks, without departing from the disclosure. 
         [0045]    The material used for constituting parts of the locking device may be metals, like steel or any other material having characteristics similar to such metals. 
       INDUSTRIAL APPLICABILITY 
       [0046]    This disclosure describes a locking device for locking devices for links of dangling grapples and links of jawsets for multi-processor devices. The main pin  60  is securely held in the bushing  32  by the locking pin  49  in the first locking position. Consequently, any inadvertent of the moving the frame  10  will not cause the main pin  60  to fall out. Dispensing with cautionary practices which may cause the main pin  60  to fall out increases efficiency of mounting or dismounting a link to a material carrier machine or changing of a grappler. 
         [0047]    Particularly, locking the main pin  60  in the bushing  32  during maintenance procedures avoids the need to manually hold or support the main pin  60 . 
         [0048]    The industrial applicability of the locking device as described herein will have been readily appreciated from the foregoing discussion. 
         [0049]    Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein. 
         [0050]    Where technical features mentioned in any claim are followed by references signs, the reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, neither the reference signs nor their absence have any limiting effect on the technical features as described above or on the scope of any claim elements. 
         [0051]    One skilled in the art will realize the invention may be embodied in other specific forms without departing from the invention or essential characteristics thereof. The foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting of the invention described herein. Scope of the invention is thus indicated by the appended claims, rather than the foregoing description, and all changes that come within the meaning and range of equivalence of the claims are therefore intended to be embraced therein.

Summary:
A locking device, in particular for a link of a grappler, comprises a movable pin provided with at least one groove, a locking plate to engage the groove and a holding element to hold the locking plate in the groove, wherein the engagement of the locking plate into the groove locks the pin. The invention also relates to a linking device comprising the locking device of the first aspect and a frame having spaced apart bushings to receive the pin. The invention further relates to a method of a method of locking a link of a grappler comprising the steps of providing a frame having spaced apart bushings, wherein at least one of the bushings carries a locking plate, threading a pin having a groove through the spaced apart bushings and engaging the locking plate into the groove.