Patent Publication Number: US-8122822-B1

Title: Bale stacker

Description:
This application is a continuation-in-part of application Ser. No. 11/853,523, filed on Sep. 11, 2007, now U.S. Pat. No. 7,610,851, which claims the benefit of U.S. Provisional Patent Application No. 60/825,172, filed Sep. 11, 2006, the entire contents of which applications are hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention is related to a bale stacker for consolidating a number of bales into a bale bundle. 
     BACKGROUND OF THE INVENTION 
     In recent years, transportation of forage over relatively long distances has been economically viable due to the prices paid for good quality forage in certain areas. Typically, a bale of hay  10  is formed which is about 18 inches wide (W), 14 inches high (H), and 35 inches in length (L) ( FIG. 1A ). As can be seen in  FIG. 1A , the bale customarily rests on a bottom wall (not shown) having an area of L×W, presenting an identical top wall (also having an area of L×W), and exposing two sidewalls, each with an area of H×W. If the forage is to be transported over long distances, it has been found to be convenient to tie a number of individual bales together into relatively large bale bundles. 
     The practice of tying a number of individual bales together to form bale bundles has developed in order to permit more economical handling of the forage in connection with its storage and transportation. In the usual current practice, twenty-one bales are stacked in seven vertical stacks of three bales each and then tied together, to form a bale bundle. 
     Machines to form bales into bale bundles are known. However, the prior art machines have a number of disadvantages. 
     SUMMARY OF THE INVENTION 
     For the foregoing reasons, there is a need for an improved machine for forming bales into bale bundles addressing or mitigating one or more of the disadvantages of the prior art. 
     In its broad aspect, the invention provides a bale stacker for forming a number of bales into a bale bundle having a predetermined number of bales. The bale stacker includes a compression chamber extending between an upstream opening and a downstream opening thereof, the bales being receivable in the compression chamber via the upstream opening and formable in the compression chamber into the bale bundle, and the bale bundle being removable from the compression chamber via the downstream opening. The bale stacker also includes a loading chamber in which the bales are positionable in respective columns proximal to the upstream opening, each column comprising a preselected number of bales, and a transfer assembly for moving the columns of said bales from the loading chamber into the compression chamber. The transfer assembly includes a platen for engaging each column of bales respectively, the platen being movable between a retracted position, in which the bales are movable into the loading chamber, and an extended position, in which each respective column of bales is positionable by the platen at least partially in the compression chamber. In addition, the bale stacker includes one or more front doors located at the upstream opening and movable between a closed position, in which the upstream opening is at least partially obstructed by the front doors, and an open position, in which each column of bales is movable respectively through the upstream opening. The bale stacker also includes one or more controlling means for coordinating movement of the front doors with movement of the platen. 
     In another of its aspects, the controlling means controls movement of the front doors so that movement of the platen from the retracted position to the extended position results in movement of the front doors from the closed position to the open position respectively, and movement of the platen from the extended position to the retracted position results in movement of the front doors from the open position to the closed position respectively. 
     In another aspect, the controlling means includes one or more linkage assemblies linking the transfer assembly and the front doors. 
     In another aspect, the front doors each include a front surface adapted for sliding engagement of each bale therewith during movement of each bale into the loading chamber. 
     In yet another aspect, the front doors are each movable between a closed position, in which a front surface thereof is disposed for supporting the bales in each column respectively located in the loading chamber, and an open position, in which each column of bales is movable respectively through the upstream opening of the compression chamber. 
     In another aspect, the front doors are each movable between a closed position, in which a front surface thereof is formed to guide the bales as they are positioned in respective columns in the loading chamber, and an open position, in which each column of bales is movable respectively through the upstream opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood with reference to the attached drawings, in which: 
         FIG. 1A  (previously discussed) is an isometric view of an individual bale of the prior art; 
         FIG. 1B  is an isometric view of an embodiment of the bale stacker of the invention, drawn at a smaller scale; 
         FIG. 2  is an isometric view of the bale stacker of  FIG. 1 , showing rear doors thereof in an open position; 
         FIG. 3A  is a side view of the bale stacker of  FIG. 2 , drawn at a larger scale; 
         FIG. 3B  is a top view of the bale stacker of  FIG. 2 , with the rear doors in the open position; 
         FIG. 3C  is a top view of the bale stacker of  FIG. 2 , with the rear doors in a closed position; 
         FIG. 4  is a partial cross-section of the bale stacker of  FIG. 3A , showing a plurality of bales in columns positioned in a compression chamber of the bale stacker with a twining material positioned around the bales; 
         FIG. 4A  is a partial cross-section of the bale stacker of  FIG. 4  with a transfer assembly positioned to move a final column in a bale bundle into the compression chamber; 
         FIG. 4B  is a partial cross-section of the bale stacker of  FIG. 4A  showing the transfer assembly pressing the bales in the compression chamber against rear doors, which are in the closed position; 
         FIG. 4C  is a partial cross-section of the bale stacker of  FIG. 4B  showing the bales in the compression chamber after compression thereof by the transfer assembly, with the rear doors in the open position; 
         FIG. 4D  is a partial cross-section of the bale stacker of  FIG. 4C  showing the bales in the compression chamber after compression thereof by the transfer assembly with the transfer assembly positioned to permit loading of the first column of a subsequent bale bundle; 
         FIG. 5  is an isometric view of an embodiment of a table assembly of the invention and an embodiment of an injector assembly of the invention, drawn at a larger scale; 
         FIG. 6A  is a top view of the table assembly of  FIG. 5  showing a first bale entering onto a table of the table assembly, drawn at a smaller scale; 
         FIG. 6B  is a top view of the table assembly of  FIG. 6A  showing the first bale and a second bale entering onto the table; 
         FIG. 6C  is a top view of the table assembly of  FIG. 6B  showing the first bale positioned in the injector assembly for loading thereby, and a third bale entering onto the table; 
         FIG. 7A  is a side view of an embodiment of the injector assembly of  FIG. 5  showing the injector assembly in a retracted condition and an initial bale positioned therein ready to be loaded into a loading chamber, drawn at a larger scale; 
         FIG. 7B  is a side view of the injector assembly of  FIG. 7A  in an intermediate condition with the initial bale partially positioned in the loading chamber; 
         FIG. 7C  is a side view of the injector assembly of  FIG. 7A  in an extended condition with the initial bale in a first (i.e., lowermost) position in the loading chamber; 
         FIG. 7D  is a side view of the injector assembly of  FIG. 7A  in an extended condition with a first column of three bales in the loading chamber, the initial bale of  FIG. 7C  being shown in a third position (i.e., highest) in the loading chamber; 
         FIG. 7E  is a partial cross-section of the loading chamber and the compression chamber showing the transfer assembly in an extended condition, after moving the first column of  FIG. 7D  through an upstream opening into the compression chamber; 
         FIG. 7F  is a partial cross-section of the loading and compression chambers, after the transfer assembly has moved a second column into the compression chamber toward a downstream opening thereof, the second column thereby pushing the first column further into the compression chamber; 
         FIG. 7G  is a partial cross-section of the loading and compression chambers, after the transfer assembly has moved a third column into the compression chamber, thereby pushing the first and second columns further into the compression chamber; 
         FIG. 8A  is a top view of another embodiment of the table assembly of the invention showing a leading bale entering onto the table, drawn at a smaller scale; 
         FIG. 8B  is a top view of the table assembly of  FIG. 8A  showing the leading bale moving underneath a spacer bar and a first following bale entering onto the table; 
         FIG. 8C  is a top view of the table assembly of  FIG. 8A  showing the leading bale positioned in the injector assembly, the first following bale moving underneath the spacer bar, and a second following bale entering onto the table; 
         FIG. 8D  is a top view of the table assembly of  FIG. 8C  showing a third following bale entering onto the table; 
         FIG. 9  is a side view of the table assembly of  FIG. 8A  showing a spacer bar, drawn at a larger scale; 
         FIG. 10A  is a side view of the spacer bar included in the table assembly of  FIG. 8A , drawn at a larger scale; 
         FIG. 10B  is a side view showing the spacer bar of  FIG. 10A  moved into a first position upon engagement of a first end of the spacer bar by the leading bale of  FIG. 8A ; 
         FIG. 10C  is a side view showing the spacer bar  10 A moved into a second position upon engagement of a second end of the spacer bar by the leading bale; 
         FIG. 10D  is a side view of a shoe on the first end of the spacer bar of  FIG. 10A  showing engagement of the first following bale with the shoe when the spacer bar is in the second position, to stop movement of the first following bale relative to the injector assembly; 
         FIG. 10E  is a side view of the spacer bar of  FIG. 10A  showing the spacer bar returning to the first position upon disengagement of the leading bale with the second end of the spacer bar; 
         FIG. 11A  is a side view of a portion of an embodiment of the bale stacker of the invention showing the compression chamber ceiling in a compression position; 
         FIG. 11B  is a side view of the portion of the bale stacker of  FIG. 11A  showing the compression chamber ceiling in a released position; 
         FIG. 12A  is a top view of an alternative embodiment of the bale stacker of the invention in which doors thereof are in a closed position; 
         FIG. 12B  is a top view of the bale stacker of  FIG. 12A  in which the doors are in an open position; 
         FIG. 12C  is a top view of the bale stacker of  FIG. 12A  in which a column of bales is positioned in a loading chamber thereof; 
         FIG. 12D  is a top view of the bale stacker of  FIG. 12C  in which a platen in a transfer assembly thereof is in an extended position, positioning the column of bales in the compression chamber; 
         FIG. 12E  is a top view of the bale stacker of  FIG. 12D  in which the platen is in a retracted position; 
         FIG. 12F  is a top view of the bale stacker of  FIG. 12E  in which a second column of bales is positioned in the compression chamber; 
         FIG. 12G  is a top view of the bale stacker of  FIG. 12F  in which the compression chamber is substantially filled with columns of bales; 
         FIG. 12H  is a side view of the bale stacker of  FIG. 12G ; 
         FIG. 13A  is a front view of an upstream opening of the compression chamber in the bale stacker of  FIG. 12B  with the doors in the open position, drawn at a larger scale; 
         FIG. 13B  is an isometric view of the bale stacker of  FIG. 13A , drawn at a smaller scale; 
         FIG. 14A  is a front view of the upstream opening of the compression chamber in the bale stacker of  FIG. 12A  with the doors in the closed position, drawn at a larger scale; 
         FIG. 14B  is an isometric view of the bale stacker of  FIG. 14A , drawn at a smaller scale; 
         FIG. 15A  is a top view of an embodiment of a linkage assembly of the invention with an arm portion thereof mounted on a frame element of the bale stacker and positioned in a first position, drawn at a larger scale; 
         FIG. 15B  is a top view of the linkage assembly of  FIG. 15A  in which the arm portion is in a second position; 
         FIG. 16A  is another top view of the linkage assembly of  FIG. 15A  with the arm portion in the first position, drawn at a larger scale; and 
         FIG. 16B  is another top view of the linkage assembly of  FIG. 16A  in which the arm portion is in the second position. 
     
    
    
     DETAILED DESCRIPTION 
     Reference is first made to  FIGS. 1B-5  to describe an embodiment of a bale stacker of the invention referred to generally by the numeral  20 . The bale stacker  20  is for consolidating a plurality of bales  10  into a bale bundle  22  ( FIG. 4D ). The bale stacker  20  includes a compression chamber  24  ( FIG. 3A ) at least partially defined by a floor  26  ( FIG. 2 ), two substantially parallel chamber sidewalls  28 ,  30  spaced apart from each other by a predetermined distance “D” ( FIG. 3B ), and a ceiling  32 . As can be seen in  FIG. 3A , the compression chamber  24  extends between an upstream opening  34  ( FIG. 4 ) and a downstream opening  36  ( FIG. 2 ). Preferably, the bales  10  are receivable in the compression chamber  24  via the upstream opening  34  and the bale bundle  22  is configured to exit the compression chamber  24  via the downstream opening  36 , as will be described. It is preferred that the compression chamber ceiling  32  includes a substantially planar rear portion  38  which is positioned substantially parallel to the floor  26 . In one embodiment, the compression chamber ceiling  32  also includes a front portion  40  which is positioned upstream from the rear portion  38  ( FIG. 3A ). Preferably, the front portion  40  is positioned in a non-parallel relationship relative to the floor  26  for engaging the bales  10  as the bales  10  are moved past the front portion  40  in a downstream direction of travel toward the downstream opening  36 , so that the bales  10  are compressed between the front portion  40  and the floor  26 . 
     The downstream direction of travel is schematically indicated by arrow “A” in  FIG. 3A . 
     It is preferred that the rear portion  38  engages the bales  10  after the bales are moved downstream past the front portion  40  so that the rear portion  38  maintains compression of the bales  10  in a direction which is substantially orthogonal to the floor  26 . Preferably, the rear portion  38  is spaced apart from the floor  26  by a distance (“B”) selected so that the bales, when positioned between the rear portion  38  and the floor  26 , are compressed to an extent desired, as will be described ( FIG. 3A ). Such compression is in a direction which is substantially orthogonal to the floor  26 . 
     It is also preferred that the front portion  40  has a length (“C”) ( FIG. 7A ) substantially aligned with the downstream direction of travel which is substantially less than one-half of a shorter dimension “H” ( FIG. 1A ) of the sidewall of each bale  10 . (As can be seen in  FIG. 1A , the shorter dimension “H” of the sidewall is the shorter of the two dimensions which substantially define the sidewall.) As will be described, the bales  10  preferably are ultimately positioned in the compression chamber resting on one sidewall thereof, with the other sidewall presented upwardly. 
     Preferably, the front portion  40  is positioned at an angle (i.e., an angle which is not zero) relative to the floor  26 , i.e., the front portion  40  is in a non-parallel relationship with the floor. Also, it is preferred that the front portion  40  is positioned in an angle relative to the floor  26  which is between approximately 30 degrees and approximately 75 degrees. Preferably, the front portion  40  is positioned at approximately 45 degrees relative to the floor  26  ( FIG. 3A ). 
     As can be seen in  FIGS. 4A-4D , the bales  10  preferably are positioned in the compression chamber  24  in columns  42 . The bale stacker  20  preferably includes a loading chamber  44  positioned adjacent to the upstream opening  34  of the compression chamber  24 .  FIGS. 7A-7D  show bales  10  being loaded into the loading chamber  44 , and put into the columns  42  in the loading chamber  44 . The bales  10  preferably are positioned in the columns  42  as they are loaded into the loading chamber  44 , as will also be described. 
     As can be seen in  FIG. 3A , the bale stacker  20  includes front doors  48  which, when in a closed position, substantially block the upstream opening  34 . Similarly, the bale stacker  20  includes one or more rear doors  52  which, when in a closed position, at least partially block the downstream opening  36  ( FIG. 3A ). (Preferably, there are two rear doors  52 , which are shown in an open position in  FIG. 3B , and in a closed position in  FIG. 3C .) The loading chamber  44  extends between a front surface  54  of the front doors  48 , when the front doors  48  are in the closed position ( FIG. 3A ), and an engagement surface  56  of a platen  58  which is included in a transfer assembly  60 . 
     The bale stacker  20  preferably also includes the transfer assembly  60 . As well as the transfer assembly  60 , the bale stacker  20  preferably additionally includes an injector assembly  62  for injecting the bales  10  into the loading chamber  44 . The bales  10  preferably are positioned in columns  42  of three bales each in the loading chamber  44  by the injector assembly  62 . The manner in which the injector assembly  62  injects the individual bales  10  is shown in  FIGS. 7A-7D , and the operation of the transfer assembly  60  to push the columns  42  into the compression chamber  24  is shown in  FIGS. 7E-7G . 
     In  FIG. 7A , the injector assembly  62  is shown in a retracted condition. As can be seen in  FIG. 7B , the injector assembly  62  includes first and second hydraulic cylinders  64 ,  66  which are operably connected to a blade  68 . The blade  68  is shown in a retracted position in  FIG. 7A , in which the bale is receivable in front of the blade  68 . Preferably, the bale  10  is positioned on a table surface  69 , as will be described. 
     When the injector assembly  62  is activated, the first bale  10  to be positioned in a new column of bales (identified as an “initial bale” in  FIG. 7A ) is engaged by the blade  68 , which, itself moved substantially horizontally to the right (as presented in  FIG. 7A ) by the first hydraulic cylinder  64 , pushes the initial bale across the table surface  69  to the right as illustrated in  FIG. 7A , i.e., in the direction indicated by arrow “A 1 ” in  FIG. 7A . 
     After it has been moved to the edge of the table surface  69 , the initial bale is pushed further by the first hydraulic cylinder  64  (via the blade), and engages a curved guide element  70 . As can be seen in  FIGS. 7A and 7B , after the bale  10  first engages the curved guide element  70 , the first hydraulic cylinder  64  continues to push the bale  10  further horizontally, i.e., to the right as shown in  FIGS. 7A and 7B . As the bale is pushed further to the right, it rotates in a counterclockwise direction (as shown in  FIGS. 7A and 7B ), and the blade  68  pivots upwardly accordingly about a pivot point  71 . 
     The first hydraulic cylinder  64  is shown in  FIG. 7B  at its maximum extension. Once the first hydraulic cylinder  64  has reached its maximum extension, the second hydraulic cylinder  66  begins to extend. As shown in  FIGS. 7B and 7C , the extension of the second hydraulic cylinder  66  in the direction indicated by arrow “A 2 ” ( FIG. 7C ) causes the blade  68  to pivot upwardly and move along a curved path, as indicated by arrow “A 3 ”. Because of the positioning of the guide element  70 , the bale is rotated (in a counterclockwise direction, as shown in  FIG. 7B ) by approximately 90 degrees as it is pushed upwardly into the loading chamber  44 . As can be seen in  FIGS. 7A-7C , due to this rotation during loading, the bale  10  is positioned in the loading chamber with the sidewalls thereof facing upwardly and downwardly, and the top and bottom sides facing the platen  58  and the front doors  48  respectively. 
     The blade  68  is shown in an extended position in  FIG. 7C , in which both the first and second hydraulic cylinders  64 ,  66  are both extended to the greatest extent possible. 
     From the foregoing, it can be seen that the first hydraulic cylinder  64  is positioned to act in a substantially horizontal direction and the second hydraulic cylinder  66  is positioned to act at an angle relative to the horizontal (i.e., in a non-parallel relationship to the table surface), to provide at least partially vertical movement of the blade  68 . The second hydraulic cylinder  66  acts in a direction which is not parallel to the direction in which the first hydraulic cylinder  64  acts. Preferably, the second hydraulic cylinder  66  is positioned at an angle of approximately 20 degrees relative to the table top surface. 
     Dogs  72  preferably are positioned at or near the top end of the guide element  70 . The dogs  72  preferably are spring-loaded or otherwise biased to an open position, the dogs  72  being shown in the open position in  FIGS. 7A-7D . Preferably, when the bale is pushed past the dogs  72  as the bale  10  is entering the loading chamber  44 , the dogs  72  pivot in the direction indicated by arrow “A 3 ” ( FIG. 7A ), to permit the bale to pass into the loading chamber  44 . It is also preferred that, once the bale is in the loading chamber  44 , the dogs  72  promptly return to the open position (as shown in  FIG. 7C ), and a portion  74  of the bale  10  engages the dogs  72  directly, so that the dogs  72  support the bale  10  ( FIG. 7C ). In addition, and as shown in  FIG. 7C , an upper portion  75  of the bale  10  simultaneously engages the engagement surface  56  of the platen  58 . In this way, the bale  10  is supported in the loading chamber  44  after it has been loaded therein. 
     A second bale and a third bale (identified as such in  FIG. 7D ) are subsequently loaded into the loading chamber  44  consecutively by the injector assembly  62  in the same manner as the initial bale. When it is loaded into the loading chamber  44 , the second bale is pushed upwardly into the loading chamber  44 , causing the initial bale to be displaced upwardly. Similarly, the third bale subsequently is loaded upwardly into the loading chamber  44  by the injector assembly  62  in the same way, moving the second and initial bales upwardly, to result in the column  42  shown in  FIG. 7D . 
     As noted above, the bales  10  are positioned in the column  42  resting on their sidewalls respectively, and the top and bottom sides of each bale face the platen  58  and the front doors respectively. Positioning the bales in this way appears to be advantageous, as will be described. 
     As can be seen in  FIG. 7C , when the initial bale is positioned in the loading chamber  44 , it is supported by the front surface  54  of the front doors  48 . The front doors  48  are biased to a closed position, preferably by springs or any other suitable biasing means. As shown in  FIG. 7D , when the first column  42  has been loaded in the loading chamber  44 , the column  42  is partly held in place by the closed front doors  48 . The bottom sides of the bales in the first column engage the front surface  54  of the front doors  48 , and rest against the front surface  54 . 
     As shown in  FIGS. 7A-7G , the floor  26  is generally positioned at about 10 degrees relative to the horizontal. This position is selected in order to facilitate movement of the bundle  22  out the downstream opening. 
     The transfer assembly  60  is for moving (or pushing) the columns  42  into the compression chamber  24 . Preferably, the platen  58  of the transfer assembly  60  includes ridges  76  in its engagement surface  56 . The ridges  76  are positioned so that they engage the lower parts of the sidewalls of the bales which are facing the platen  58  when the column  42  is in position in the loading chamber  44  ( FIG. 7D ). When the column  42  is formed, the bales tend to overhang slightly towards the front. The ridges  76  are positioned as described above so as to counteract this tendency, i.e., the ridges  76  cause the bales in the column  42  to become somewhat better vertically aligned with each other because the ridges engage the lower parts of the sidewalls which face the platen  58  first. 
     Once the first column  42  is positioned in the loading chamber  44 , the platen  58  is moved in the direction shown by arrow “A 4 ” in  FIG. 7E , pushing the first column of bales through the front doors  48 . As can be seen in  FIG. 7E , once the first column of bales has been pushed past the front doors  48 , the first column holds the front doors  48  in an open position. The first column is positioned in  FIG. 7E  to provide some support for the bales in the immediately following column, as such bales are loaded. In this way, the first column of bales and subsequent columns of bales serve to assist in supporting each column of bales subsequent thereto as each such subsequent column is loaded respectively. 
     After the initial and second bales in a column have been loaded, the blade  68  is retracted, i.e., both of the hydraulic cylinders sequentially retract (the second hydraulic cylinder  66  first, and the first hydraulic cylinder  64  next) to their fully retracted positions. However, after the third bale is loaded for a particular column, the blade  68  remains in the extended position, to support the column ( FIG. 7D ). This has been found to be advantageous because the front edge of the lowermost bale in the column tends to drop down if not supported by the blade  68 . The blade  68  remains in the extended position until the column  42  has been pushed into the compression chamber  24 . 
       FIG. 7F  shows the platen  58  after it has pushed (in the direction shown by arrow “A 5 ” in  FIG. 7F ) a second column of bales (as identified in  FIG. 7F ) into the compression chamber  24 . As can be seen in  FIG. 7F , when the second column of bales is pushed into the compression chamber  24 , the first column of bales engages the front portion  40  of the compression chamber ceiling  32 , causing the first column of bales to be compressed. 
       FIG. 7G  shows a third column of bales (identified in  FIG. 7G ) after it has been pushed (in the direction shown by arrow “A 6 ”) into the compression chamber  24 . As can be seen in  FIG. 7G , when the third column of bales is pushed into the compression chamber  24 , the third column pushes the second column of bales further into the compression chamber  24 , and the second column of bales in turn pushes the first column further into the compression chamber  24 . Also, as the third column is pushed into the compression chamber by the platen  58 , the second column engages the front portion  40  of the ceiling  32 , which compresses the second column. The first column remains compressed, by the rear portion  38 . 
     In accordance with customary practice, the bundle  22  preferably includes seven columns of three bales each, i.e., 21 bales in all. A group  78  of 21 bales in seven columns ready to be tied and further compressed (i.e., ready to be consolidated into a cohesive bundle) is shown in  FIG. 4 . Also,  FIG. 4  shows a tying material  80  which defines a pocket into which the seven columns of bales in the group  78  preferably have been pushed, one column at a time, as described above. (The tying material  80  is not shown in  FIGS. 7E-7G  for clarity of illustration.) The tying material  80  is shown in  FIG. 4  prior to its being tied around the bales  78  using a knotter  82 . The technique of tying bales and bundles of bales generally, and using knotters therefor, is well-known, and therefore such technique does not need to be described in detail here. 
       FIGS. 4A-4D  show a series of steps taken after the seventh column (i.e., the final column in the group  78 ) of bales has been loaded. It will be understood that tying material  80  is present in  FIGS. 4A-4D , although the tying material is not shown, for clarity of illustration. 
     In  FIG. 4A , a seventh column (i.e., the last column in the group  78  shown) is shown in the loading chamber  44 . As shown in  FIG. 4A , the platen  58  is about to push in the direction shown by arrow “A 7 ”. In  FIG. 4B , the platen  58  pushes the seventh column into the compression chamber  24 , causing the first column in the group  78  to engage the inside surface  50  of the rear doors  52 , which are closed. Accordingly, the group  78  is shown in  FIG. 4B  positioned in the compression chamber  24 , after the seventh column has been pushed into the compression chamber  24 . At this point, the compression of the group  78  of bales in the direction of downstream travel (i.e., lengthwise) takes place, i.e., due to the platen  58  pushing the seventh column into the compression chamber  24 . The group  78  is tied with tying material  80  (i.e., twine) while such compression is taking place. 
     While the group  78  of bales is compressed by the transfer assembly  60 , the knotter  82  ties the tying material  80  around the group  78  of bales. Once the tying has been completed, the group of bales  78  has been consolidated into the bale bundle  22 . 
     It is important for the tying to take place during compression lengthwise because, after such compression, the material in the bales rebounds. It is intended that the rebounding of the material in the bales will exert outward pressure on the tying material  80 , thereby causing the tying material  80  to hold the bales together tightly. As is known in the art, it is desirable that the bales be held together in the bundle as tightly as possible. 
     After such lengthwise compression and the tying, the rear doors  52  are opened. This causes the resilient rebounding of the material (i.e., hay) to take place which is directed primarily rearwardly, rather than frontwards. Frontward expansion is not possible at this point because the platen  58  is still in position, engaged with the seventh column. 
     It has been found that compression of the bales from top to bottom thereof is generally easier than compression thereof from sidewall to sidewall. This is due to the manner in which the bales are made, and the resilient nature of the hay. For this reason, the bales are positioned in the compression chamber  24  with sidewalls directed upwardly and downwardly. Accordingly, the bundle  22  is more likely to hold its shape better when the bales used to form it are positioned as described. 
     When the bales  10  are formed, they are bound with twine or any other suitable tying material, as is known in the art, and each bale has some degree of structural strength, or internal cohesiveness. When consolidating the bales into the bale bundle, it is desirable to compress the bale bundle before tying, because the hay is resilient, and rebounds after tying, and after the compression is released, so that the bales tightly press outwardly against the tying material. This outward expansion or rebounding is important because it is undesirable that bales in a bundle be “loose”, as this may interfere with stacking the bundle, or otherwise working with the bundle. However, over-compression of individual bales can be harmful, especially over an extended period of time, because such over-compression can eliminate or reduce the internal cohesiveness of the bale, and undermine its ability to rebound after compression. 
     Accordingly, the extent of compression of each bale, and the direction in which each bale is compressed, preferably is controlled in the bale stacker. Because the bales are more easily compressed in a direction which is from top wall to bottom wall (or vice versa), the bales are positioned on their sidewalls in the loading chamber  44  (i.e., in the columns) and subsequently in the compression chamber. (The bales are also positioned in this way because this is more suitable for the desired dimensions of the bundle after it has been formed.) Conversely, compression of each bale in the other direction (i.e., sidewall to sidewall) is somewhat more difficult, and therefore is limited to the extent caused by the front portion  40  and maintained by the back portion  38 . 
     The bundles preferably are sized to fit into a high cube van, which has an inside height of approximately 110 inches. Preferably, each bundle is formed so that two bundles (one on top of another) can relatively easily fit into the high cube van. In practice, this means that the bundles preferably should have a height of approximately 52 to 53 inches, or less. Because of this, the rear portion preferably is approximately 51 inches above the floor  26 . 
     Compression orthogonal to the floor  26  is maintained by the rear portion  38  over an extended period of time. This is advantageous because it results in relatively close control over the ultimate height of the bundle, after consolidation thereof. As indicated above, the height of the bundle preferably is about 52 or 53 inches (or less), for easier loading into a high cube van. However, the lengthwise compression is done over a minimal period of time, e.g., over approximately five seconds, so that the hay will rebound (after tying) to a significant extent in the lengthwise direction. In this way, the desired height of the bundle is substantially maintained, and the hay rebounds generally in the lengthwise direction to a desired extent. 
     In  FIG. 4D , the platen  58  is shown in a retracted position, so that the first column of the next group of bales (i.e., to be formed into another bundle) may be loaded into the loading chamber  40 . Preferably, the bundle  22  shown in  FIG. 4D  is pushed out of the compression chamber  24  when the subsequent columns of the following group of bales (not shown in  FIG. 4D ) are pushed into the compression chamber  24  by the platen  58 . (Depending on conditions, five or six subsequent columns may be loaded and pushed into the compression chamber before the bundle  22  is pushed out.) The bundle  22  exits via the downstream opening, and rolls down a ramp  83  which preferably is included in the bale stacker  20  to facilitate movement of the bundle  22 . Preferably, the ramp has rollers or other means for promoting movement of the bundle down the ramp  83  under the influence of gravity, as is known in the art. 
     From the foregoing description, it can be seen that the extent of compression lengthwise is important—i.e., such compression should preferably be only to the desired extent. The distance between the surface  56  of the platen  58 , when the transfer assembly  60  is fully extended, and the front surface  50  of the rear doors  52 , when the rear doors  52  are closed, preferably is adjustable, so that the conditions of the bales can be taken into account and the lengthwise compression is kept within the desired range. As can be seen in  FIGS. 3B and 3C , the surface  50  preferably is on two separate panels  85  formed with mounting elements  87  which are mounted on arms  89  respectively. The mounting elements  87  include holes  91  in which pins  93  are receivable, the mounting elements  87  being temporarily (but securely) attachable to the arms  89  by the pins  93 . As can be seen in  FIGS. 3B and 3C , the position of the panels  85  on the mounting elements  87  can be changed so that the panels  85  are further out or closer to the arms  89  respectively, as the case may be. Accordingly, the position of the front surface  50  relative to the surface  56  of the platen  58  (when the platen is fully extended) can be varied by attaching the mounting elements  87  at various of the holes  91 . 
     As indicated above, the bales preferably are provided to the injector assembly  62  on the table surface  69 . The bale stacker  20  preferably includes a table assembly  84  ( FIG. 5 ). The table assembly  84  is for transporting bales to the injector assembly  62 . The table assembly  84  preferably includes a table  86  having the substantially flat table surface  69 . It is preferred also that the table surface  69  is adapted to permit sliding movement of the table  86  under the bale. The table assembly  84  preferably also includes a means  129  for rotating the table  86  about a substantially vertical axis  131  ( FIG. 9 ). As can be seen in  FIG. 9 , the axis  131  preferably is defined by an axle element  133 , to which is attached a sprocket  135  or similar device. The means  129  preferably also includes a motor  137  for rotating the table  86 , and a power transmission element  139  connecting the motor and the sprocket  135 . As will be appreciated by those skilled in the art, there are many different ways in which rotation of the table  86  could be effected, and the means for rotation  129  illustrated in  FIG. 9  is exemplary only. 
     It is also preferred that the table assembly  84  includes a bale control device  88  ( FIG. 9 ) for spacing the bales apart from each other on the table surface  69  by an approximate predetermined distance, as will be described. The bale control device  88  causes the bales to be provided to the injector assembly  62  at discrete intervals, thereby preventing the bales from interfering with the operation of the injector assembly  62  by clogging it. 
     The manner in which the table assembly  84  transports bales to the injector assembly  62  is shown in  FIGS. 6A-6C . In  FIG. 6A , a first bale (identified as such) is moved in the direction shown by arrow “A 8 ” by a baler (not shown) along a chute  90  onto the table  86 . (As will be described, the bale stacker  20  may be used with a baler or otherwise.) As can be seen in  FIG. 6A , the table  86  preferably rotates in a counterclockwise direction, as indicated by arrow “A 9 ”. The table  86  preferably includes an inner guide element  92  and an outer guide element  94  which serve to channel the bales toward the injector assembly  62 . The guide elements  92 ,  94  are stationary relative to the moving table  86 . 
     As can be seen in  FIGS. 6A ,  6 B, and  6 C, the first bale and a second and a third bale preferably are placed on the table surface  69  spaced apart an approximate predetermined distance from each other. (As described below, the transportation of the bales by the table  86  to the injector assembly  62  preferably is controlled at least in part by the bale control device  88  in any event.) The path taken by the bales is generally indicated by arrows in  FIG. 6B , and as can be seen in  FIG. 6C , the net result is that a sidewall of the first bale  10  is positioned for engagement with the blade  68  of the injector assembly  62 . The injector assembly  62  preferably includes a bale stop  96  which moves in concert with the blade  68 , as will be described. The bale stop  96  also partially controls the movement of bales to the injector assembly  62 . 
     The use of the bale control device  88  (referred to hereinafter as a spacer bar) and the bale stop  96  to control the movement of bales on the table is shown in  FIGS. 8A-8D ,  9 , and  10 A- 10 E. As can be seen in  FIGS. 8A and 8B , the spacer bar has an elongate body  98 . In  FIG. 8B , a leading bale is moved by the table  86  underneath an upstream end  101  of the body  98 . The leading bale is shown in  FIG. 8C  as having been received in the injector assembly  62 , and is positioned in front of the blade  68 . In the meantime, after the leading bale moves past a downstream end  103  of the body  98 , a first following bale moves underneath the upstream end  101  of the body  98  ( FIG. 8C ). At the same time, a second following bale is placed on the table  86  ( FIG. 8C ). 
     In  FIG. 8D , because the first hydraulic cylinder  64  of the injector assembly  62  is extended at least somewhat, the bale stop  96  prevents the first following bale from proceeding further, and consequently interfering with the operation of the injector assembly. Because the downstream end  103  of the body  98  is positioned on the first following bale, the upstream end  101  is positioned to prevent the second following bale from proceeding further towards the injector assembly  62 , as will be described. As can be seen in  FIG. 8D , a third following bale is unable to proceed onto the table, because the second following bale is (at the point shown in  FIG. 8D ) bumping into the second following bale. The relative positions of the bale control device  88  and the bale stop  96 , when the blade is in the extended position, are shown in  FIG. 9 . (The second hydraulic cylinder  66  in the injector assembly  62  has not been shown in  FIG. 9  for clarity of illustration.) 
     The operation of the spacer bar (or bale control device)  88  is shown in  FIGS. 10A-10E . As can be seen in  FIG. 10A , the body  98  of the spacer bar  88  is pivotable about a pin  105 . The body  98  is pivotable between a first position ( FIG. 10B ), in which the upstream end  101  is raised to permit the leading bale to pass underneath the upstream end  101  and the downstream end  103  is correspondingly lowered, and a second position ( FIGS. 10C and 10D ), in which the downstream end  103  is raised to engage the leading bale. When the downstream end  103  is so raised, the upstream end  101  is correspondingly lowered. As can be seen in  FIGS. 8A-8D  and  10 A- 10 E, the table surface  69  is adapted to move relative to the bale while the bale is restrained by the upstream end  101 , and the table surface  69  ultimately moves the bale past the upstream end  101 . As described above, the bale may be held under the downstream end  103  for some time because the bale is held substantially stationary relative to the spacer bar  88  by the bale stop  96 , i.e., the bale engages the bale stop  96  when the bale stop is in its path. However, once the bale stop  96  is moved out of the path of the bale, the bale is moved by the table  86  away from the spacer bar  88 , and into position in front of the blade  68  of the injector assembly  62 . 
     Preferably, the spacer bar  88  includes a shoe  107  mounted on a pin  109  extending from a bracket  111  positioned at the upstream end  101 . Preferably, the shoe is pivotable between an up position ( FIG. 10D ) and a down position ( FIGS. 10A-10C ,  10 E) about the pin  109 . The shoe  107  has an engagement surface  112 , and is biased by a biasing means  113  (preferably, a spring) to the down position. 
     As can be seen in  FIG. 10A , when the body  98  is positioned midway between its first and second positions, an initial bale engages the shoe  107  beneath a midway point  115  on the engagement surface  112 , so that the bale engages the shoe  107  and slides underneath the shoe  107 , causing the body&#39;s upstream end  101  to pivot upwardly, and also consequently causing the downstream end  103  to pivot downwardly to a corresponding extent. Preferably, the body  98  is balanced so that, when neither of the ends  101 ,  103  is engaged with a bale, the body  98  is positioned in the midway position shown in  FIG. 10A . 
     As shown in  FIG. 10B , when the body  98  is in the first position, the shoe  107  permits the bale to pass underneath the upstream end  101 . The shoe  107  preferably engages the top side of the bale as it passes underneath the upstream end  101 . 
     As can also be seen in  FIG. 10B , the downstream end  103  is configured so that the bale pushes the downstream end  103  upwardly to the second position, when the bale engages the downstream end  103 . In  FIG. 10C , the body  98  is shown in the second position thereof, with the downstream end  103  lightly engaged with the top side of the initial bale. The upstream end  101  is lowered to a corresponding extent, with the result that the first following bale engages the shoe engagement surface  112  at a point above the midway point  115 . In this situation, instead of the first following bale sliding underneath the shoe  107 , the first following bale engages the shoe  107 , and causes the shoe  107  to pivot upwardly to the up position ( FIG. 10D ). With the body  98  and the shoe  107  in this position, the bale is stopped from proceeding, as it can be seen that the first following bale cannot pass underneath the upstream end  101  when the shoe is positioned relatively low with respect to the bale&#39;s top side. The table surface  69  continues to move underneath the bale relative to the bale&#39;s bottom side, creating a relatively light pressure causing the bale to press forwardly, i.e., past the upstream end  101 . 
     Finally,  FIG. 10E  shows that, once the initial bale moves past the downstream end  103 , the upstream end  101  is moved upwardly by the shoe  107 . This takes place because the shoe  107  presses down on the bale as it returns to the position to which it is biased, causing the upstream end to move upwardly. In this position, the first following bale engages the shoe  107  at a point below the midway point  115 , so that the first following bale can push the upstream end upwardly, and pass underneath the upward end  101 . 
     As can be seen in  FIGS. 11A and 11B , the compression chamber ceiling  32  is movable between a compression position ( FIG. 11A ) and a released position ( FIG. 11B ). In the released position, the ceiling  32  is located approximately three to four inches above the ceiling  32  when it is in the compression position. 
     This feature is useful when, for example, the bundle  22  is to be removed from the compression chamber  24 , but there are no additional bales available for processing. Such a situation may arise, for example, when the bales in a particular field have been collected, and no bales remain in such field. In particular, this feature of the invention is useful where, for example, the bale stacker  20  is used for consolidating bales from different farmers, i.e., the operator of the bale stacker is working on a contract basis, and mixing of bales from different fields is undesirable. 
     As can be seen in  FIG. 11A , the ceiling  32  preferably is mounted to a frame  117  of the bale stacker via a parallel linkage which includes pins  119 ,  121 ,  123  and  125 . As can be seen in  FIGS. 11A and 11B , the movement of the ceiling  32  from the compression position to the released position and vice versa is effected by movement of a lever  127 . The movement from the compression position to the released position is upwardly and generally toward the rear, as indicated by arrow A 10 . It can be seen in  FIGS. 11A and 11B  that, after moving the ceiling  32  to the released position, the bundle  22  can be pulled out of the compression chamber (e.g., by a tractor) relatively easily. 
     In use, the bale stacker is positioned as required. The bale stacker  20  preferably is mounted on wheels, and may be towed to a location where bales are fed to it, for example, via the chute  90 . Alternatively, the bale stacker  20  may be towed in a field, with a device (e.g., a suitable conveyor) adapted to pick up bales directly in the field. 
     The bales are placed on the table  86 , and as described, the spacer bar  88  and the bale stop  96  are used to control the flow of the bales to the injector assembly  62  so that the bales are fed to the injector assembly one at a time, when the blade  68  is retracted and ready to receive the next bale. The injector assembly  62  loads the bales one at a time into the loading chamber  44 , to form columns  42  of three bales each. Each column  42  is separately pushed into the compression chamber  24  by the transfer assembly  60 . With the seventh (and final) column for a particular group of bales  78  which is to be formed into a bundle, the push given to such seventh column by the transfer assembly (when the column is pushed into the compression chamber) serves to compress the entire group of twenty-one bales lengthwise. Such lengthwise compression is to a predetermined extent. 
     In addition, as each column is pushed past the front portion  40  of the ceiling  32 , the front portion compresses the column orthogonally relative to the floor  26  of the compression chamber  24 . Such compression is intended to be limited to a certain extent, in order that the internal cohesiveness of the bales might not be adversely affected by such compression. After the column  42  moves past the front portion  40 , compression thereof orthogonal to the floor is maintained by the rear portion  38 . 
     The group  78  is tied off while it is being compressed as described, so that the bales in the group  78  are consolidated into the bale bundle  22 . Before the platen  58  is retracted, the rear doors  52  are opened, to permit a resilient expansion of the hay in the bundle  22  towards the downstream opening, generally in the downstream direction. Subsequently, the platen  58  is fully retracted, so that the subsequent columns of bales for the next group of bales may be loaded into the loading chamber  44 . When the subsequent columns of the next group of bales are pushed into the compression chamber, they in turn push the bale bundle  22  out of the compression chamber, via the downstream opening. Preferably, the bundle  22  rolls down the ramp  83  under the influence of gravity. After the bundle  22  has exited the compression chamber  24 , the rear doors  52  are closed, in preparation for the lengthwise compression of the next group of bales. 
     Additional embodiments of the invention are shown in  FIGS. 12A-16B . In  FIGS. 12A-16B , elements are numbered so as to correspond to like elements in  FIGS. 1B-11B . 
     An alternative embodiment of a bale stacker  220  of the invention is shown in  FIGS. 12A-16B . The bale stacker  220  is for forming a number of bales  10  into the bale bundle  22  having a predetermined number of bales  10 . Preferably, the bale stacker  220  includes a compression chamber  224  extending between an upstream opening  234  and a downstream opening  236  thereof ( FIGS. 12A ,  12 B). The bales  10  are receivable in the compression chamber  224  via the upstream opening  234  and are formable in the compression chamber  224  into the bale bundle  22 . The bale bundle  22  is removable from the compression chamber  224  via the downstream opening  236 . Also, the bale stacker  220  preferably includes a loading chamber  244  in which the bales  10  are positionable in respect of columns  242  proximal to the upstream opening  234 . Each column  242  includes a preselected number of bales  10 , as will be described. The bale stacker  220  preferably also includes a transfer assembly  260  for moving the columns  242  of bales  10  from the loading chamber  244  into the compression chamber  224 . In one embodiment, it is preferred that the transfer assembly  260  includes a platen  258  for engaging each column  242  of bales respectively. It is also preferred that the platen  258  is movable between a retracted position ( FIG. 12A ), in which the bales  10  are movable into the loading chamber  244 , and an extended position ( FIG. 12B ), in which each respective column  242  of bales  10  is positionable by the platen  258  at least partially in the compression chamber  224 . Preferably, the bale stacker  220  also includes one or more front doors  248  located at the upstream opening  234  and movable between a closed position ( FIG. 14A ), in which the upstream opening  234  is at least partially obstructed by the front doors  248 , and an open position ( FIG. 13A ), in which each column  242  of bales  10  is movable respectively through the upstream opening  234 . In addition, the bale stacker  220  preferably also includes one or more controlling means  273  for coordinating movement of the front doors  248  with movement of the platen  258 . 
     In one embodiment, the controlling means  273  controls movement of the front doors  248  so that movement of the platen  258  from the retracted position to the extended position results in movement of the front doors  248  from the closed position to the open position respectively, and movement of the platen  258  from the extended position to the refracted position results in movement of the front doors  248  from the open position to the closed position respectively ( FIGS. 12A ,  12 B). 
     The controlling means are for controlling movement of the front doors relative to movement of the platen, i.e., for coordinating movement of the front doors with movement of the platen. It will be appreciated by those skilled in the art that the controlling means  273  may include various arrangements of various components. For instance, in one embodiment, the controlling means  273  may include one or more hydraulic cylinders controlled by limit switches and a PLC computer. 
     It is preferred that the controlling means  273  includes one or more linkage assemblies  241  linking the transfer assembly  260  and the front doors  248 . As will be described, the linkage assembly  241  is a mechanical linkage. The linkage assembly has a cost advantage over a controlling means which includes one or more hydraulic cylinders, as will be appreciated by those skilled in the art. However, as indicated above, the controlling means are not necessarily driven or moved by movement of the platen  258  or other components of the transfer assembly  260 . 
     Preferably, the transfer assembly  260  includes a cam surface  243  extending between a first end  245  and a second end  247  thereof movable with the platen  258  ( FIG. 15B ). In one embodiment, the linkage assembly  241  preferably includes a roller  249  adapted for rolling engagement with the cam surface  243  and an arm portion  251  extending between a back end  253  thereof, disposed proximal to the front door  248 , and a front end  255  thereof, disposed distal to the front door  248 . The arm portion  251  is connected to the front door  248  ( FIG. 15A ). In one embodiment, the arm portion  251  is pivotable about an axis  257  between a first position ( FIG. 15A ), in which the front door  248  is located thereby in the closed position, and a second position ( FIG. 15B ), in which the front door  248  is located thereby in the open position. Preferably, the cam surface  243  is configured so that movement of the platen  258  between the retracted and the extended positions thereof causes the arm portion  251  to pivot between the first and second positions respectively, and also causes corresponding movement of the front doors  248  between the closed and open positions respectively. 
     The problem which the bale stacker  220  addresses is described as follows. In the first embodiment of the bale stacker  20  (described above), the first column of bales for a particular bale bundle engage the front surface  54  of the front doors  48  ( FIGS. 7C ,  7 D). However, as can be seen in  FIGS. 4A-4D ,  7 E- 7 F, and  9 , once the first column is pushed past the front doors  48 , the front doors  48  are held open by the first column and successive columns positioned at the front end of the compression chamber, until the bale bundle is completed. 
     Accordingly, when the second and subsequent columns are loaded into the loading chamber, the immediately preceding column is located at the front end of the compression chamber. In the bale stacker  20 , the bales in the second and subsequent columns in a particular bale bundle therefore are slidingly engaged with the bales in the immediately preceding column, when the second and subsequent columns are moved into the loading chamber  44  of the bale stacker  20 . In this situation, however, the bales being loaded sometimes are caught on the bales in the immediately preceding column. This can result in the bales being turned as they are loaded into the loading chamber  44 , due to catching on the bales in the immediately preceding column. When this happens, the generally straight, generally upward path of the bale being loaded is interrupted. It will be appreciated by those skilled in the art that the bale which is being loaded may be turned sufficiently that the loading chamber becomes blocked thereby. Such jamming is to be avoided, to the extent possible, because productivity is adversely affected when time must be spent to clear the blocked loading chamber. In practice, this problem is generally only occasional, however, it can be frequent if the hay in the bales is relatively wet. For instance, the hay may be relatively damp due to prevailing weather conditions. 
     In the bale stacker  220 , this problem is addressed, or at least mitigated. The front doors  248  address the issue in two ways. First, the front surfaces  254  preferably are relatively smooth, and are positioned so that the bales being loaded into the loading chamber  244  are slidingly engageable therewith. 
     Second, the front doors  248  return to the closed position after a column is pushed into the compression chamber. As can be seen, for example, in  FIGS. 12D  and  12 E, when the platen  258  moves from the extended position ( FIG. 12D ) to the retracted position ( FIG. 12E ), the front doors  248  are moved from the open position to the closed position respectively. In this way, the front doors  248  are returned to the closed position after each column of bales is pushed from the loading chamber into the compression chamber. 
     Accordingly, each front door  248  preferably includes the front surface  254  thereof adapted for sliding engagement of each bale therewith during movement of each bale into the loading chamber  244 . From the foregoing, it can be seen that, because the front doors  248  are positioned so that bales slidingly engage the front surfaces  254  of the doors  248  as the bales are loaded into the loading chamber  244 , the problem of bales becoming jammed in the loading chamber is substantially addressed. 
     As can be seen in  FIG. 14B , the loading chamber  244  preferably is positioned at an angle to the horizontal (i.e., higher at the front than the back), so that each bale (and each column of bales), while in the loading chamber, is at least partially supported by the front doors  248 . 
     Also, the front doors  248  preferably are formed to at least partially guide the bales as they are moved into the loading chamber  244 . For instance, in one embodiment, the front surfaces  254  are substantially flat, and guide bales upwardly as the bales are loaded into the loading chamber. 
     As can be seen in  FIGS. 12A-12H , the platen  258  preferably includes one or more body elements  261  with surfaces  263  thereof which are substantially flat and smooth (i.e., to define a plane), and also substantially parallel to the front surfaces of the front doors  248 . Preferably, the body elements  261  define gaps  265  therebetween ( FIGS. 12A ,  12 C,  12 E). The gaps  265  enable tying material  280  ( FIG. 12H ) to be drawn around the bales as they are compressed, so that the bales can be tied while compressed, to form the bale bundle. Any suitable means for moving the platen  258  between the extended and the retracted positions may be used. For instance, in one embodiment, the platen  258  preferably is moved between the extended and retracted positions by one or more hydraulic cylinders. 
     In one embodiment, the axis  257  is located proximal to the front end  255  of the arm portion  251  ( FIGS. 16A ,  16 B). As can be seen in  FIGS. 15A-16B , the roller  249  preferably is mounted on the arm portion  251  and the arm portion  251  is pivotably mounted to a frame  259  ( FIGS. 15A ,  15 B) of the bale stacker  220  so that the cam surface  243  moves relative to the roller  249  when the platen  258  moves between the retracted and extended positions thereof. 
     Those skilled in the art would be aware of various arrangements of the components of the linkage assembly which would be suitable. In one embodiment, the cam surface  243  includes a first portion  269  which is substantially parallel to the direction of travel of the platen  258  between the retracted and extended positions, and a second portion  271  which is positioned at a predetermined angle relative to the first portion  269  ( FIGS. 16A ,  16 B). The arm portion  251  and the front door  248  attached thereto are formed so that, when the roller  249  engages the first portion  269 , the front door  248  is held in the open position. Also, when the roller  249  moves from the first portion  269  to the second portion  271 , the front door  248  moves from the open position and toward the closed position. The front door  248  reaches the closed position when the roller  249  reaches the end of its path along the second portion  271  of the cam surface  243 , as shown in  FIGS. 15A and 16A . 
     It will be understood that the linkage assemblies  241  mounted on each side of the bale stacker  220  are the same in all material respects, except that they are mirror images of each other. 
     As can be seen in  FIGS. 13B and 14B , the linkage assembly  241  preferably includes an upper arm portion (identified as  251   a  in  FIGS. 13B and 14B  for convenience) and a lower arm portion (identified as  251   b  in  FIGS. 13B and 14B  for convenience). Preferably, the upper and lower arm portions  251   a ,  251   b  are connected by a connecting rod  267  which strengthens the linkage assembly, as it urges the upper and lower arm portions  251   a ,  251   b  to move substantially simultaneously. 
     It will also be understood that the upper and lower arm portions are the same in all material respects. 
     Those skilled in the art will appreciate that a variety of arrangements may be used for moving bales into the loading chamber  244 . However, in one embodiment, the bale stacker  220  preferably includes an injector assembly  262  ( FIG. 12H ) for moving the bales into the loading chamber  244  and positioning the bales in columns respectively therein. 
     In addition, it will be appreciated by those skilled in the art that the bales may be fed to the injector assembly  262  using various devices or methods. In one embodiment, the bale stacker  220  preferably also includes a table assembly  284  for transporting each bale consecutively to the injector assembly  262  and positioning each bale respectively for movement thereof by the injector assembly  262 . 
     In use, the bales preferably are positioned on the table assembly  284  consecutively (i.e., one at a time). The methods and devices which may be used to position the bales consecutively on the table assembly  284  are well known in the art, and it is therefore unnecessary to describe such methods and devices in detail. Preferably, each bale is positioned by the table assembly  284  in the injector assembly  262  consecutively, so that each bale preferably is then loaded into the loading chamber  244  consecutively. The bales may be positioned consecutively in the injector assembly in the manner described above, in connection with the bale stacker  20 . As described above, the bales preferably are loaded into the loading chamber  244  by the injector assembly one at a time to form a three-bale column. Preferably, the loading chamber  244  is at least partially defined by the platen  258  and the front surfaces  254  of the front doors  248 , and the loading chamber  244  is substantially filled by the column of three bales. 
     Because the bale bundle ultimately is preferably formed of a total of 21 bales (i.e., seven columns of three bales each), it is expeditious to form each column of three bales in the loading chamber. However, it will be understood that the columns of bales may include any suitable numbers of bales, as required. 
     In  FIG. 12A , the bale stacker  220  is shown after a bale bundle (not shown) has been formed and pushed out of the compression chamber  224 . The platen  258  is in the refracted position, and the bales of the first column in the next bale bundle are receivable in the loading chamber  244 . 
     In  FIG. 12B , the platen  258  is shown in the extended position, for illustrative purposes. 
     The first column  242  of three bales is shown positioned in the loading chamber  244  in  FIG. 12C . It will be understood that the bales  10  in the column  242  preferably are loaded into the loading chamber  244  by the injector assembly  262 . Each bale preferably is pushed generally upwardly (i.e., in the direction indicated by arrow “M” in  FIG. 12H ) into the loading chamber  244  by the injector assembly  262  in the manner described above in connection with the bale stacker  20 . However, the column  242  is positioned in the loading chamber  244  using any suitable means. 
     In  FIG. 12D , the first column (identified in  FIG. 12D  as  242   a  for convenience) has been moved rearwardly, from the loading chamber  244  into the compression chamber  224 , by the platen  258  as it moves from the retracted position ( FIGS. 12A ,  12 C) to the extended position ( FIGS. 12B ,  12 D). The direction of such movement is indicated by arrow “N” in  FIG. 12D . 
       FIG. 12E  shows the platen  258  returned to the retracted position, i.e., after the platen  258  has moved from the extended position to the retracted position. The direction of such movement is indicated by arrow “P” in  FIG. 12E . As shown in  FIG. 12E , upon the platen  258  returning to the retracted position, the next column of bales is receivable in the loading chamber  244 . 
     In  FIG. 12F , the second column of bales (identified as  242   b  in  FIG. 12F  for convenience) is shown being positioned in the compression chamber  224  by the platen  258 . The platen  258  is shown in the extended position in  FIG. 12F . As the column  242   b  is pushed into the compression chamber  224  (i.e., in the direction indicated by arrow “Q” in  FIG. 12F ), the column  242   b  engages column  242   a , and pushes column  242   a  rearwardly. 
       FIG. 12G  shows the columns needed to form the bale bundle positioned in a group  278  in the compression chamber  224 . As can be seen in  FIG. 12G , when the platen  258  pushes the final column for the bale bundle to be formed (such final column being identified as  242   g  in  FIG. 12G  for convenience) into the compression chamber  22 , rear doors  252  are closed. The platen  258  is shown in the extended position in  FIG. 12G . Preferably, after the final column for a particular bale bundle is positioned in the compression chamber, the platen  258  pushes further rearwardly (i.e., to a position rearward of the extended position), to compress all the bales in the bale bundle while the bale bundle is tied off. 
     The group  278  of 21 bales in seven columns ready to be tied and further compressed (i.e., ready to be consolidated into a cohesive bundle) is also shown in  FIG. 12H . Also,  FIG. 12H  shows a tying material  280  which defines a pocket into which the seven columns of bales in the group  278  preferably have been pushed, one column at a time, as described above. (The tying material  280  is not shown in  FIGS. 12A-12G  for clarity of illustration.) The tying material  280  is shown in  FIG. 4  prior to its being tied around the bales  278  using a knotter  282 . The technique of tying bales and bundles of bales generally, and using knotters therefor, is well-known, and therefore such technique does not need to be described in detail here. 
     Any element in a claim that does not explicitly state “means for” performing a specified function, or “step for” performing a specific function, is not to be interpreted as a “means” or “step” clause as specified in 35 U.S.C. §112, paragraph 6. 
     It will be appreciated by those skilled in the art that the invention can take many forms, and that such forms are within the scope of the invention as claimed. Therefore, the spirit and scope of the appended claims should not be limited to the descriptions of the preferred versions contained herein.