Abstract:
A locking device that connects to a grooved end of a dragline pin includes a lock block and a lock pin. The lock block has a through opening sized to receive the end of the pin. There is a bore formed in the lock block and transversely intersecting the through opening which is dimensioned to receive the lock pin. The lock pin is configured to pass through a portion of the grooved end of a received dragline pin received in the through opening to lock the dragline pin and any attached dragline component.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims priority from pending Australian Patent Application No. 2011253753, filed Nov. 30, 2011, which is incorporated herein by reference. 
     BACKGROUND 
     This application relates to dragline equipment, and in particular, to a locking device used to secure a pin connection of a dragline. 
     Dragline rigging, i.e., the system of wire ropes, chains and links that suspend and guide a dragline bucket during use, includes a number of pivot connections that each has a pin. These pivot connections are subjected to heavy loads and harsh working environments, so ultimately they wear and require replacement. 
     Typically, such pins have been retained or “locked” in place by passing the pin through an opening or a pair of aligned openings in a link or other component and then a plate or washer, and then welding a bead of material around the protruding end of pin. The bead makes the end of the pin larger than the opening(s), so the pin is retained in place. Welded connections take time and skill to complete, and the quality of the weld can be difficult to assess. 
     Some efforts at mechanical retaining pins have been made, but these have other drawbacks. For example, two-piece “clamshell” collars shaped to fit grooves at the end of pins and secured by one bolt at either side are quicker and easier to install. In some environments, however, the exposed bolted connections are subjected to wear and tear during use that no longer allows for easy disassembly. 
     It would be advantageous to provide a dragline pin connection locking device that is quick and easy to install, secure and has a long useful life. 
     SUMMARY 
     Described below is a dragline pin locking device that connects to a grooved end of a dragline pin and has a lock block with a through opening sized to receive the end of the pin, a bore formed in the lock block and transversely intersecting the through opening, and a lock pin sized for insertion through the bore. The lock pin is configured to pass through a portion of the grooved end of a dragline pin received in the through opening, thereby locking the dragline pin in place. 
     The foregoing and other objects, features, and advantages of the invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a dragline pin locking device showing the lock block with the lock pin removed and before assembly over the end of a dragline pin. 
         FIG. 2  is a top plan view of the lock block and lock pin of  FIG. 1  installed over the end of a dragline pin. 
         FIG. 3  is a front elevation view of the lock block and lock pin of  FIG. 2 . 
         FIG. 4  is a side elevation of the lock block and lock pin of  FIG. 2 . 
         FIG. 5  is a sectioned front elevation view of the lock block and lock pin of  FIG. 2 . 
         FIG. 6A  is a right side elevation view of a lock block and lock pin assembled to lock a portion of a dragline component to a dragline pin. 
         FIG. 6B  is a front elevation view of the assembly of  FIG. 6A , taken at the line  6 B- 6 B. 
         FIG. 6C  is a left side elevation view of the assembly of  FIG. 6A   
     
    
    
     DETAILED DESCRIPTION 
     A representative embodiment of a locking device  10  for dragline pins is shown in  FIGS. 1-5 . The locking device  10  is dimensioned to connect to a dragline pin, a portion of which is shown at  12  in the figures. 
     The locking device  10  includes a lock block  14 , a lock pin  18  and a bore  16  dimensioned to receive the lock pin  18 . The bore  16  extends through the lock block  14  in a direction transverse to a through opening  20  dimensioned to receive the dragline pin  12 . The bore  16  intersects the through opening  20 , preferably at about 90 degrees, and extends in a direction tangential to the through opening  20 . 
       FIG. 1  shows an end of the dragline pin  12  before it is fitted with the locking device  10 .  FIGS. 2-5  show the locking device  10  fitted to the dragline pin  12 , but before it has been secured in place. When the locking device is secured to the dragline pin  12 , the locking device  10  and the dragline pin  12  cannot translate relative to each other, but relative rotation is possible. 
     In some embodiments, the locking device  10  is configured to have a side surface  19  that abuts against a shoulder  22  ( FIG. 1 ) on the dragline pin  12  when the locking device  10  is secured to the dragline pin  12 . In some embodiments, the dragline pin  12  has a circumferential groove  24  positioned between the shoulder and an end surface  26  of the dragline pin  12 , and the lock pin  18  is configured to extend through a portion of the groove  24 . 
     When installed, the lock pin  18  serves to lock or retain the lock block  14  on the dragline pin  12 . There may be a threaded arrangement between the lock pin  18  and the lock block  14 . Alternatively, the lock pin  18  may be rotatably engageable with the lock block  14 . In the illustrated implementation, the bore  16  has an inner surface in which a groove  40  is defined. The lock pin  18  has a nib  34  sized to be inserted in the groove  40 . The groove  40  can define a generally helical path  41  as shown. As the lock pin  18  is inserted into the bore  16 , the nib  34  is aligned with the groove  40 . Rotating the lock pin  18  clockwise causes it to be drawn into the lock block  14  until the end of the groove  40  is reached. There can be a recess or detent  42  defined at the end of the groove for retaining the nib  34  while the device is in a locked condition. Optionally, a corresponding groove  40 ′ and recess  42 ′ can be defined at the other end of the bore. In one embodiment, the grooves  40  and  40 ′ provide for about 90 degrees of rotation in the lock pin  18 . 
     Optionally, there is an insert  36  made of a resilient material and shaped as a hollow cylinder having a slot  38 . The insert  36  can be configured for positioning at one end of the bore  16  where the groove  40  or  40 ′ is in use, such as in a counterbore  52 . The insert is dimensioned such that it must be compressed slightly to allow the nib to be rotated into the recess  42  or  42 ′. In this way, the compressed insert exerts an axial retaining force on the lock pin  18  tending to keep it in the locked position. The other end of the bore  16  can be fitted with a cap  48 , such as in a counterbore  52 ′, to prevent dirt and debris from entering the assembly and to make clear which end of the bore is configured to receive the lock pin  18 . 
     The lock pin  18  comprises a head  32  attached to a shaft  30 . The head  32  can have a recess shaped to receive any suitable drive to assist in rotating the lock pin  18 , such as a ¾″ square drive as shown. 
     The lock block  14  can have a generally D-shaped cross-section as shown in  FIGS. 3 and 5 . The top surface  50  can be generally planar, and a curved side surface  52  can adjoin both ends of the top surface. The head  32  of the lock pin  18  is preferably flush with a surrounding seating area portion  60  of the side surface  52  when the lock pin  18  is fully inserted in the bore  16 . Likewise, the cap  48  is preferably flush with a surrounding seating area portion  60 ′ when it is fully inserted. 
     The through opening  20  can be elongated. In the illustrated embodiments, the through opening  20  has a greatest dimension D larger than a diameter d of the end of the dragline pin  12 . 
     Referring to  FIGS. 6A-6C , the lock block  14  is shown assembled to lock a dragline component, a portion of which is shown in section at  70 , in place on the pin  12 . The dragline component can have a bushing  72  with an opening sized to receive the pin  12 . The bushing  72  can have an eccentric configuration with a shallower section  74  and a deeper section  76 . The deeper section  76  is arranged according to where greater wear is expected as the component  70  rotates relative to the pin  12 , in this case along the region that counteracts a load P on the pin  12  in the direction of the arrow. 
     Referring again to  FIG. 6A , the deeper section  76  of the bushing  72  has a dimension f. As can be seen, the through opening  20  is sized greater than the diameter of the pin  12 , and there is a clearance between the pin  12  and the opening  20  of a dimension e as shown. Further, the dimension e is greater than the dimension f. In this way, even if the bushing  72  were to wear completely (i.e., the depth of the bushing was reduced from f to zero), the end of the pin  12  would still be separated from the lower boundary of the through opening  20 , thus preventing inadvertent contact and wear between these surfaces. 
     The lock block and the lock pin can be made from any suitable materials, such as high strength steel, although any suitable material can be substituted. The insert can be made of a resilient material, such as a resilient polymeric material. 
     The lock block may be embodied as a separate component as shown in the illustrated embodiments to form a locking connection with a pin. As described above, the pin is usually attached to a first component. Further, as shown in  FIGS. 6A-6C , there may a second component sandwiched between the first component and the lock block. Alternatively, the lock block may be attached to yet another component—such as by being welded to that component—that is to be connected by the pin connection. In addition, the lock block may be embodied in a larger component as part of a pin connection for that component. For example, the lock block structure can be integrally formed with the component, such as being cast into the component. 
     In view of the many possible embodiments to which the principles of the present disclosure can be applied, it should be recognized that the illustrated embodiments are only examples and should not be taken as limiting the scope of the following claims. We therefore claim all that comes within the scope and spirit of these claims.