Abstract:
A track end connector with a simple single bolt means to secure the pins from adjacent track shoes and hold the pins in a relationship so the track shoes have the desired angular orientation relative to each other.

Description:
GOVERNMENT INTEREST  
       [0001] The invention described here may be made, used and licensed by and for governmental purposes without paying me any royalty. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    In one aspect this invention relates to tracked vehicles. In yet a further aspect this invention relates to the construction of endless tracks.  
           [0003]    Track laying vehicles such as tanks ride on an endless track structure. Such tracks consist of a series of track shoes having pins that extend outward perpendicularly to the track shoe. Adjacent track shoes are held in a spaced array by means of end connectors that engage the pins extending from the track shoe. Several methods have been proposed for holding the pins in the end connector. The most commonly used technique is the use of a bolt that engages a wedge that in turn engages a milled portion of the pin in within the track shoe. Such connectors have a problem in that the bolt tends to loosen as the track is used requiring frequent re tightening of the bolt. The frequent need to tighten and retorque the bolts sometimes results in failure of the bolt heads requiring extensive work to repair the track strand.  
           [0004]    It would be desirable to have an end connector that is simpler in construction. A further desirable feature would be a connector that will visually show when the bolt is beginning to loosen so it can be easily retorqued.  
         SUMMARY OF THE INVENTION  
         [0005]    The end connector system of this invention is a simplified system used for joining adjacent sections of double pin track shoes to form an endless track strand. The system uses an end connector with a connector body having two spaced, parallel track pin apertures. The apertures are adapted to receive and hold the pins that extend outward from the track shoe. Adjoining track shoes pins are thus held in a parallel relationship and the track shoes will form a continuous strand of track, which can be extended to the desired length and then closed to form an endless loop. The end connector body has a shaped bore disposed orthogonally to and located between the pin apertures, with an opening on one surface of the connector body; the shaped bore having a portion which overlaps into the track pin apertures. The shaped bore has a threaded section distal the opening in the connector body surface.  
           [0006]    A bolt having a threaded portion complimentary to and adapted to engage the threaded portion of the bore is used to hold the track shoe pins. The threaded portion is sized so it will pass through the bore in the end connector without engaging the pins from the track shoe when they are disposed in the apertures. The bolt has a land section juxtaposed the threaded section the land section being of a diameter which will substantially fill the volume of the shaped bore which is common with track pin apertures. When the bolt is fully seated in the bore, the land section is adapted to engage a cam surface formed on the pins of the track shoes as the bolt is tightened to hold the pins within the connector body. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    In the accompanying drawing:  
         [0008]    [0008]FIG. 1 is a side view in partial section of one end connector of this invention;  
         [0009]    [0009]FIG. 2 is a view of the end connector of FIG. 1 with the bolt partially inserted;  
         [0010]    [0010]FIG. 3 is a view of the end connector of FIG. 1 with the bolt fully tightened; and  
         [0011]    [0011]FIG. 4 is a partial view of a pin used with the track shoe with the cam surface exposed. 
     
    
     DETAILED DESCRIPTION  
       [0012]    Referring to the accompanying drawing wherein like numerals refer to like parts, an end connector system for joining adjacent sections of double pin track shoes (not shown) to form an endless track is designated generally  10 . The system includes a connector body  12 , a bolt  14  that are adapted to engage and hold the substantially cylindrical pins  16  extending from a track shoe only a portion of the pin being shown.  
         [0013]    The end connector body  12 , has two spaced, parallel track pin apertures  18 , which are parallel to each other and pass entirely through the body of the end connector. The apertures  18  are adapted to receive and hold pins  16  from adjoining track shoes in the track strand and maintain the pins in a spaced parallel relationship. The end connector body  12  has a shaped bore which is formed in the body orthogonal to and located midway between the pin apertures  18 , with an opening  22  on one surface of the connector body. The shaped bore  20  has an enlarged portion beginning at the opening on the body surface and extending into the body a portion of the enlarged bore overlapping the track pin apertures  20  to create a shared volume within the connector body  12 . The shaped bore  20  has a threaded section  24  distal the opening  22  in the end connector body  12  the threaded section having a diameter smaller than the enlarged bore portion.  
         [0014]    The bolt  14  to be used in the practice of this invention is formed with a threaded portion  26  that is complimentary to and adapted to engage the threaded section  24  of the bore  20 . The threaded portion  26  is sized with respect to length and diameter so it will pass through the enlarged portion of bore  20  without engaging the pins  16  from the track shoes while they are disposed in the apertures  18 . The threaded portion  26  is also sufficiently long that it can engage the threaded section  24  for at least one turn during installation before contacting any of the remainder of the track connector elements.  
         [0015]    Bolt  14  has a land section  28  juxtaposed the threaded portion  26 . The land section  28  has a diameter which will substantially fill the enlarged section of the shaped bore  20  including the volume of the shaped bore which is common to the pin apertures  18  when the bolt  14  is fully seated in the bore. The land section  28  is being adapted to engage a cam surface  30  formed on the pins  16  of the track shoes as the bolt  14  is tightened to hold the pins within the connector body  12  as described below.  
         [0016]    The installation sequence of the end connectors is illustrated taking the FIGS. 1-3 in numerical order. In FIG. 1, the pins  16  from two separate track shoes have been inserted into the apertures  18 . As shown in FIG. 1 the cam surface  30  will form a slight angle with the axis of the shaped bore  20 . The surfaces will be on the order 5 to 10 degrees with a desired angle of about 7 degrees.  
         [0017]    The bolt  14  will be inserted into the shaped bore  20  until the threaded section  24  engages the threaded portion  24  of the shaped bore and the bolt rotated the complimentary threads drawing the bolt into the shaped bore. At this stage the bolt is firmly anchored but the enlarged section of the bolt is just coming into contact with the cam surface  30 . For heavy track shoe applications, such as a tank, the bolt  14  will have about 0.10 to 0.20 inch of engagement to provide proper strength.  
         [0018]    As the bolt  14  is tightened it will reach the final result shown in FIG. 3 where the bolt is completely within the shaped bore and the land section has engaged the cam surface  30 . This results in a slight rotation of the pins to align the cam surfaces with the axis of the shaped bore. This will cause the track shoes to have an angle of about  14  degrees with respect to each other. The tightening of the bolt  14  the unthreaded cam surface  28  is drawn further along the essentially parallel cam surface. When fully seated, the bolt  14  resembles a locking pin where nearly all the forces acting on the bolt are normal to the bolt surface. There remains only a moderate force parallel to the bolt surface resulting from the clearance between the parts and gravity. In the fully tightened position the bolt&#39;s head is flush with the connector body  12  so it is easy to see if the bolt  14  is loosening as the head will become exposed and proper corrective measures can be promptly applied. It is expected the frictional forces applied to the enlarged section  28  of the bolt  14  by the cam surfaces  30  on the pins  16  will also serve to hold the bolt within the bore  20 .  
         [0019]    As shown the bolt  14  has a hexagonal keyway  34  extending through the bolt. This allows the bolt to be accessed from either side to allow tightening or removal should the bolt  14  break during installation or repair. This solves the problem of prior art track structures where the breakage of a bolt head would require drilling out the remaining bolt to separate track elements.  
         [0020]    Various alterations and modifications will become apparent to those skilled in the art without departing from the scope and spirit of this invention and it is understood this invention is limited only by the following claims.