Abstract:
A drilling machine including a chassis and a primary rod box mounted on the chassis, which includes a rod box interface mechanism positioned adjacent a top of the primary rod box for facilitating interfacing the primary rod box with a supplemental rod box is provided. Another aspect of the present disclosure relates to a rod box interface mechanism that automatically secures a rod box to a drilling machine as the rod box is lowered in place on the drilling machine. The rod box interface mechanism can in some embodiments be used to secure a supplemental rod box to a top of a primary rod box that is attached to a chassis of the drilling machine and can be used to secure a rod box directly to the chassis of the drilling machine. A further aspect of the present disclosure relates to self-aligning features intended to guide a rod box into place on a drilling machine as the rod box is lowered onto the drilling machine.

Description:
[0001]    This application is being filed on 29 Nov. 2011, as a PCT International Patent application in the name of Vermeer Manufacturing Company, a U.S. national corporation, applicant for the designation of all countries except the US, and Russel Novelo, Michael D. Belloma, Ryan P. Roberts, Lucas Layerman, David Langenfeld and Ward Ryon, citizens of the U.S., applicants for the designation of the US only, and claims priority to U.S. Provisional Patent Application Ser. No. 61/418,670, filed Dec. 1, 2010, which is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    Drill rods used with a horizontal directional drilling machine are commonly stored in containers, commonly called rod boxes. These rod boxes typically store the rods stacked in multiple columns, and are configured for transferring rods out of the bottom of the rod box to a rod loading mechanism which, during a drilling operation, moves the rods from the rod box and into alignment with a drill string. The rod loading mechanism is capable of reversing the direction of transfer, to transfer rods back into the rod box during a pull-back operation. Examples of horizontal directional drilling machines with various types of rod storage and handling mechanisms are described in U.S. Pat. Nos. 6,360,830; 6,332,502; 5,607,280; 5,556,253; 6,474,932; 6,374,928; 7,694,751; 7,562,724; 7,240,742; 6,085,852; 7,600,584; and U.S. Pat. No. 6,374,927, the disclosures of which are hereby incorporated by reference. 
         [0003]    For larger drills, that are capable of drilling extended distances, it is not practical to store all the required rods on the machine. Thus, these larger machines typically have the ability to add additional rods to the drill string by removing an empty rod box, and installing a full rod box during a drilling operation, and of reversing that to remove a full rod box, and replace it with an empty box during a pull-back operation. 
         [0004]    There is a need for a system to optimize processes related to the handling of the rod boxes. 
       SUMMARY 
       [0005]    One aspect of the present disclosure relates to a drilling machine including a chassis and a primary rod box mounted on the chassis. The drilling machine includes a rod box interface mechanism positioned adjacent a top of the primary rod box for facilitating interfacing the primary rod box with a supplemental rod box. 
         [0006]    Another aspect of the present disclosure relates to a rod box interface mechanism that automatically secures a rod box to a drilling machine as the rod box is lowered in place on the drilling machine. In certain embodiments, the rod box interface mechanism is used to secure a supplemental rod box to a top of a primary rod box that is attached to a chassis of the drilling machine. In other embodiments, the rod box interface mechanism can be used to secure a rod box directly to the chassis of the drilling machine. 
         [0007]    A further aspect of the present disclosure relates to self-aligning features intended to guide a rod box into place on a drilling machine as the rod box is lowered onto the drilling machine. In one embodiment, the self-alignment features include a tapered alignment pin and a notched alignment pin. 
         [0008]    A variety of additional aspects will be set forth in the description that follows. These aspects can relate to individual features and to combinations of features. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad concepts upon which the embodiments disclosed herein are based. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a perspective view of a horizontal directional drilling machine in accordance with the principles of the present disclosure; 
           [0010]      FIG. 2  is a front end view of the horizontal directional drilling machine of  FIG. 1 ; 
           [0011]      FIG. 3   a  is an enlarged view of a portion of  FIG. 1  showing a first retention structure provided at a first end of a primary rod box of the horizontal directional drilling machine of  FIG. 1 ; 
           [0012]      FIG. 3   b  illustrates the first retention device of  FIG. 3   a  being used to latch the first end of the primary rod box to a first end of a supplemental rod box; 
           [0013]      FIG. 4  is an enlarged view of a portion of  FIG. 1  showing a second retention device provided at a second end of the primary rod box; 
           [0014]      FIGS. 5   a - 5   c  show a sequence of steps for latching the first end of the supplemental rod box to the first end of the primary rod box; 
           [0015]      FIGS. 6   a - 6   e  show a sequence of steps for unlatching and removing the supplemental rod box from the primary rod box; 
           [0016]      FIGS. 7   a - 7   e  show a sequence of steps for temporarily unlatching and then re-latching the supplemental rod box to the primary rod box; 
           [0017]      FIG. 8  is an exploded view of a latching assembly of the first retention device of  FIG. 3   a;    
           [0018]      FIG. 9  is a perspective view of a first end of the supplemental rod box; 
           [0019]      FIG. 10  is another perspective view of the horizontal directional drilling machine of  FIG. 1 ; 
           [0020]      FIG. 11  is an enlarged view of a portion of  FIG. 10  showing a second end of the supplemental rod box; 
           [0021]      FIG. 12  is an enlarged view of a portion of  FIG. 10  showing an enlarged view of a second end of the primary rod box; 
           [0022]      FIG. 13  shows the second end of the supplemental rod box in the process of being coupled to the second end of the primary rod box; 
           [0023]      FIGS. 14   a - 14   e  show a sequence of steps for interlocking the second end of the supplemental rod box with the second end of the primary rod box; 
           [0024]      FIG. 15  is a cross-sectional view taken along section line  15 - 15  of  FIG. 14   e ; and 
           [0025]      FIGS. 16   a - 16   d  show an overall sequence for securing/attaching the supplemental rod box to the primary rod box. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    Horizontal directional drilling machines include a variety of mechanical systems with variations that have been developed to meet the needs of a variety of applications. Many of these applications involve bores that are relatively short such as crossing roads or streams and rivers, or installing utilities from a road-side to a residence. The machines typically used for this type of short installation include a drill rod handling device and drill rod storage with enough drill rod carried on the machine for an individual project. However, other applications require significantly longer bores. For such applications, it is not practical for the drill rod storage device of the drilling machine to carry all the drill rods necessary to complete the job, as the drill rod storage device would be unreasonably large. The present disclosure is directed to a drill rod handling system suitable for use in efficiently drilling both long and short bores. 
         [0027]      FIG. 1  illustrates the basic mechanical elements of a horizontal directional drilling machine  100 . The drilling machine  100  has a power unit  102  that typically includes a diesel engine and hydraulic pumps. The power unit  102  could alternately include an electric motor. The power unit  102  of this embodiment is mounted to a machine chassis  103  that includes ground drive tracks  108 . The drilling machine  100  also includes a drive arrangement for driving the drill string into the ground and for pulling the drill string back from the ground. In certain embodiments, the drive arrangement includes a drive unit (e.g., a gear box) having a rotational driver that provides torque for rotating the drill string about an axis of rotation  106  during drilling operations. The drive unit also can include a thrust/pull-back driver for pushing the drill string into the ground during drilling operations and for pulling the drill string back from the ground during back reaming and/or pull back operations. The drive unit is typically capable of sliding back and forth along the axis of rotation during drilling and pull-back/backreaming operations. Many different drive arrangement configurations are possible. Example drive arrangement configurations may include linear actuators, rack and pinion gear systems or other known mechanical components. An example drive arrangement is disclosed at U.S. Pat. No. 6,814,164, which is hereby incorporated by reference herein in its entirety. 
         [0028]    Referring to  FIGS. 1-4 , the drilling machine  100  includes drill rod handling system  120  including a first rod shuttle  122 , a second rod shuttle  124 , a primary rod box  126  mounted to the chassis  103 , and at least one supplemental rod box  200  that mounts to a top of the primary rod box  126 . 
         [0029]    The rod shuttles  122 ,  124  can reciprocate along horizontal axes oriented generally perpendicular relative to the axis  106  to move rods back and forth between the bottom discharge of any column of the primary rod box  126  and into alignment with the axis  106  of the drill string.  FIG. 2  shows the rod shuttles (the rod shuttle  124  is hidden behind the rod shuttle  122 ) in a retracted position in which pockets  123  of the rod shuttles are positioned directly beneath a column of the primary rod box  126  from which it is desired to receive a rod. From the retracted position, the shuttles  122 ,  124  can be moved linearly to an extended position where the pockets  123  are positioned to align a rod held within the pockets  123  with the axis of rotation  106 . The shuttles  122 ,  124  have blocking surfaces  125  that block lower ends of the columns of the primary rod box  126  when the shuttles  122 ,  124  are in the extended position to prevent the rods from unintentionally falling from the rod box  126 . It will be appreciated that the present disclosure is not limited to any particular type of rod transfer device. While a preferred embodiment describes a rod handling system that includes rod boxes that discharge drill rods from the bottom into a rod shuttle device, aspects of the present disclosure can be advantageous for use with any rod handling system. 
         [0030]    The primary rod box  126  typically has a rod storage capacity that is only large enough to allow the drilling machine to drill bores of a predetermined length. For longer bores, additional rod capacity can be provided by mounting the supplemental rod box  200  on top of the primary rod box  126 . In the depicted embodiment, the primary rod box  126  is connected to the chassis  103  by a first connection type and the supplemental rod box  200  is connected to the primary rod box  126  by a second connection type. The primary rod box  126  is typically not removed from the chassis  103  during normal use of the drilling machine  100 . Thus, the first connection can be permanent (e.g., welded) or semi-permanent (e.g., secured in place by a plurality of fasteners such as bolts or other fasteners which typically require tools for assembly and disassembly). In contrast, when drilling long bores multiple supplemental rod boxes  200  may be mounted consecutively to the top of the primary rod box  126 . For example, when the primary rod box is empty, a first supplemental rod box is connected to the top of the primary rod box and used to re-fill the primary rod box  126  with rods. Thereafter, if more rods are needed, the first supplemental rod box is removed from the top of the primary rod box  126  and replaced with a second supplemental rod box that is used to re-fill the primary rod box  126 . This process is repeated until the bore is complete. Because the supplemental rod boxes are often being connected and disconnected from the primary rod box  126 , the second connection type preferably allows the supplemental rod boxes to be quickly and easily connected to and disconnected from the top of the primary rod box  126 . Thus, the second connection type preferably allows for quicker connections and disconnections than the first connection type. In a preferred embodiment, the second connection type is a tool-less connection in which separate tools (e.g., wrenches) are not needed by the operator to connect and disconnect the supplemental rod box to and from the primary rod box. In a more preferred embodiment, the supplemental rod box automatically connects to the primary rod box when the supplemental rod box is lowered on the primary rod box. 
         [0031]    Referring to  FIG. 10 , the primary rod box  126  of the drilling machine  100  includes a magazine frame  127  defining a rod storage region having a top  129  and a bottom  131 . The magazine frame  127  defines a plurality of vertical columns  130 ,  132  and  134  that extend from the top  129  to the bottom  131  of the rod storage region of the magazine frame  127 . The columns  130 ,  132  and  134  have lengths that extend from a first end  133  to a second end  135  of the magazine frame  127 . The columns have open top and bottom ends. The shuttles  122 ,  124  are mounted beneath the open bottom ends of the columns  130 ,  132 ,  134  of the primary rod box  126 . 
         [0032]    The primary rod box  126  is attached to an elongated frame  104  of the chassis  103 . The frame  104  is pivotally movable relative to a main body of the chassis  103  between a horizontal position (see  FIG. 10 ) and an angled position. When the frame  104  is in the angled position, a first end  105  of the frame  104  is elevated relative to a second end  107  of the frame  104 . The primary rod box  126  is carried by the frame  104  as the frame is pivoted between the horizontal and angled positions. When the frame  104  is in the horizontal position, both ends  133 ,  135  of the rod box  126  are at the same elevation and both of the shuttles  122 ,  124  are at the same elevation. When the frame is in the angled orientation, the first end  133  of the rod box is at a lower elevation than the second end  135  of the rod box  126  (see  FIGS. 16   a - 16   d ) and the first shuttle  122  is at a lower elevation than the second shuttle  124 . 
         [0033]    Referring still to  FIG. 10 , the supplemental rod box  200  of the drilling machine  100  includes a magazine frame  327  defining a top  329  and a bottom  331 . The magazine frame  327  defines a plurality of vertical columns  330 ,  332  and  334  that extend from the top  329  to the bottom  331  of the magazine frame  327 . The columns  330 ,  332  and  334  have lengths that extend from a first end  333  to a second end  335  of the magazine frame  327 . The columns  330 ,  332 ,  334  are open at the top  329  and bottom  331  of the magazine frame  327  and are adapted to align with the columns  130 ,  132  and  134  of the primary rod box  126  when the supplemental rod box  200  is mounted on the primary rod box  126 . Removable retaining members  339  can be mounted across the open lower ends of the columns  330 ,  332  and  334  at the bottom  331  of the magazine frame  327  to prevent the rods from falling from the open lower ends of the columns  330 ,  332  and  334  during transit of the supplemental rod box  200 . 
         [0034]    Referring to  FIGS. 16   a - 16   d , the drilling machine  100  also includes a pair of lift arms  143  for raising and lowering the rods within the primary rod box  126 . The lift arms include rod support portions  145  on which the rods of the primary rod box  126  rest. By pivoting the lift arms  143  from an intermediate position where the rod support portions  145  are positioned slightly higher than the blocking surfaces  125  of the shuttles  122 ,  124  to a fully lowered position where the rod support portions  145  are lower than the pockets  123  of the shuttles  122 ,  124 , a rod from a column positioned over the pockets  123  can be lowered into the pockets  123 . The lifting arms  143  are also movable from the intermediate position to a fully raised position where the rod support portions  145  are positioned above the top  129  of the primary rod box  126 . When a loaded supplemental rod box  200  is initially mounted on the top  129  of the primary rod box  126  while the primary rod box  126  is empty, the lifting arms  143  can be moved to the fully raised position thereby causing the lifting arms to lift the rods slightly within the supplemental rod box  200  to allow rod retaining members  339  to be removed from the bottom of the supplemental rod box  200 . Once the rod retaining members  339  have been removed from the supplemental rod box, the rods held within the columns of the supplemental rod box  200  can be lowered by the lifting arms  143  into the corresponding columns  130 ,  132 ,  134  of the primary rod box  126 . 
         [0035]    The primary rod box  126  includes a rod box interface mechanism at the top of the primary rod box  126  for facilitating interfacing the primary rod box  126  with the supplemental rod box  200 . In one embodiment, the rod box interface mechanism can include a rod box retention arrangement configured to automatically latch the supplemental rod box  200  to the top of the primary rod box  126  when the supplemental rod box  200  is lowered onto the primary rod box  126 . The rod box retention arrangement can include a first retention structure  150  (see  FIG. 3   a ) positioned adjacent the first end  133  of the magazine frame  127  and a second retention structure  140  (see  FIGS. 4 and 12 ) provided adjacent the second end  135  of the magazine frame  127 . The first retention structure  150  includes a first guide pin  152  that projects upwardly from a top surface of the magazine frame  127  and a latch mechanism  160  including a latching arm  162 . The second retention structure  140  includes a second guide pin  142  including an undercut region  243  defining a catch  144  formed by a bevel. The undercut region  243  faces away from the first guide pin  152 . In certain embodiments, the catch can be formed by a beveled portion of the second pin  142  or by a slight misalignment of the second pin  142 . The first guide pin  152  has a tapered configuration with a tapered portion  153  that faces away from the second guide pin  142  and that diverges from the second guide pin  142  as the tapered portion  153  extends in a downward direction. 
         [0036]    The supplemental rod box  200  includes structure that interfaces with the first and second retention structures  150 ,  140 . For example, the supplemental rod box  200  includes first and second flanges  202 ,  206  mounted at the bottom of the magazine frame  327 . The first flange  202  (see  FIG. 9 ) is positioned at the first end  333  of the magazine frame  324  and the second flange  206  (see  FIG. 11 ) is positioned at the second end  335  of the magazine frame  327 . The first flange  202  defines a first flange opening  204  and the second flange  206  defines a second flange opening  208 . When the supplemental rod box  200  is mounted on the primary rod box  126 , the first guide pin  152  is received within the first flange opening  204  and the second guide pin  142  is received within the second flange opening  208 . 
         [0037]      FIGS. 16   a - 16   d  show a sequence for attaching the supplemental rod box  200  to the top of the primary rod box  126 . Initially, the supplemental rod box  200  in maneuvered such that the second guide pin  142  is received within the second flange opening  208  (see  FIG. 16   a ) and the first flange is elevated above the first guide  152 . Next, the supplemental rod box  200  is pivoted downwardly about the second guide pin  142  such that the first flange opening  208  moves toward the first guide pin  152  (see  FIGS. 16   b  and  16   c ). As the supplemental rod box  200  is pivoted downwardly, a tip of the first guide pin  152  is received within the first flange opening  204 . Continued downward movement of the first end  333  of the supplemental rod box  200  causes the first flange  202  to slide along the tapered portion  153  of the first guide pin  152  which causes the supplemental rod box  200  to slide in a direction  212  which is generally parallel to the axis of rotation  106 . As the supplemental rod box  200  slides in the direction  212 , an end portion  211  of the second flange  206  slides toward the first guide pin  152  into the undercut region  243  of the second guide pin  142  beneath the catch  144 . In this position, interference between the second flange  206  and the catch  144  provides an interlock that prevents the flange  206  from being lifted off of the second guide pin  142 . Once the supplemental rod box  200  slides in the downward direction  147  a sufficient distance for the first guide pin  152  to pass fully through the first flange opening  204 , the first flange  202  seats on the top surface  129  of the magazine frame  127  and the latching arm  162  automatically latches over the first flange  202  such that the first flange  202  is prevented from being lifted off the first guide pin  152 . In this way, by latching the flanges  202 ,  206  to the top of the primary rod box  126 , the supplemental rod box  200  is securely connected to the top side of the primary rod box  126 . 
         [0038]      FIGS. 3   a ,  3   b ,  5   a - 5   c ,  6   a - 6   e  and  7   a - 7   e  show the latch mechanism  160  in a variety of configurations illustrating its functions.  FIG. 5   a  illustrates the basic components of the latch mechanism  160  including the latching arm  162 , a latch dog  164 , a latch assembly biasing device  166  (e.g., a coil extension spring), and a plunger  168 . The latching arm  164  is pivotally connected to the primary rod box  126  at pivot axis  170  and is pivotally movable between a latching position (see  FIGS. 5   a  and  5   c ) and a non-latching position (see  FIG. 6   c ). The top of the frame magazine  127  of the primary rod box  126  includes an upper wall  129  having an upper surface  128  on which the first end  333  of the supplemental rod box  200  seats when the supplemental rod box  200  is latched to the primary rod box  126 . A coil spring  173  or other biasing member is mounted between the upper wall  229  and a lower plunger mounting wall  175  attached to the first end  133  of the primary rod box  126 . The plunger  168  is able to slide relative to the walls  229 ,  175  along a vertical axis  177 . The plunger  168  is movable along the axis  177  between an upper position (see  FIGS. 5   a  and  5   b ) and a lower position (see  FIG. 5   c ). In the upper position, the plunger  168  extends through an opening in the upper wall  229  such that an upper portion  179  of the plunger  168  projects above the top surface  128 . In the lower position, the plunger  168  extends through an opening in the wall  175  such that a lower portion  181  of the plunger  168  projects below a bottom surface of the wall  175 . The spring  173  biases the plunger toward the upper position. 
         [0039]    The latch assembly biasing device  166  biases the latching arm  162  toward the latching position. The latch dog  164  is pivotally connected to the latching arm  162  at pivot axis  165 . The latch dog  164  is pivotally movable about the pivot axis  165  relative to the latching arm  162  between an upper position (see  FIGS. 5   a  and  5   b ) and a lower position (see  FIG. 5   c ). The latch assembly biasing device  166  biases the latch dog  164  toward the upper position. A lever  183  can be used by an operator to manually pivot the latch dog  164  from the upper position to the lower position. 
         [0040]    A sequence for latching the flange  202  of the supplemental rod box  200  to the upper wall  229  of the primary rod box is shown at  FIGS. 5   a - 5   c .  FIG. 5   a  shows the latching arm  162  in the latching position prior to mounting the supplemental rod box  200  on the primary rod box  126 .  FIG. 5   b  illustrates the supplemental rod box  200  in the process of being positioned on top of the primary rod box  126 , where the flange  202  contacts an angled ramp surface  163  of the latching arm  162 . Upon contact between the flange  202  and the ramp surface  163 , the weight of the supplemental rod box  200  is sufficient to overcome the bias of the biasing device  166  and force the latching arm  162  to rotate counter clockwise about its mounting axis  170  toward the non-latching position. Once the removable rod box  200  is seated against the upper surface  128 , the latching arm  162  is able to rotate clockwise, due to biasing device  166 , to engage flange  202 , thus locking the supplemental rod box  200  to the primary rod box  126 , without requiring an operator to do anything more than to position and lower the supplemental rod box  200  into position. 
         [0041]    As the supplemental rod box  200  moves into the seated position, flange  202  forces the plunger  168  down as illustrated in  FIG. 5   c . This device serves a function for removing the supplemental rod box  200 , as illustrated in  FIGS. 6   a - e .  FIG. 6   a  is the same as  FIG. 5   c , with the removable rod box  200  seated on the primary rod box  126 , and retained by the latching arm  162 . In the position of  FIG. 6   a , the lower portion  181  of the plunger  168  engages the latch dog  164  to retain the latch dog in the lower pivot position. If an operator wishes to remove the supplemental rod box  200 , the first step is to reposition the latch plate  162 , by manually moving it counter-clockwise to the non-latching position as shown in  FIG. 6   b . When the latching arm  162  reaches the non-latching position, the latch dog  164  disengages from the bottom end of the lower portion  181  of the plunger  168  and the biasing device  166  pivots the latch dog  164  to the upper pivot position. The latching arm  162  is then released and the biasing device  166  moves the latching arm slightly back toward the latching position until the latch dog  164  contacts the side of the lower portion  181  of the plunger  168  (see  FIG. 6   c ). Contact between the latch dog  164  and the side of the lower portion  181  of the plunger  168  retains the latching arm in the non-latching position. The supplemental rod box  200  can then be lifted off the primary rod box  126 , as illustrated in  FIG. 6   d , without interference from the latching arm  162 . As the supplemental rod box is lifted, the spring  173  causes the plunger  168  to move back to the upper position. When the plunger moves back to the upper position, the lower portion of the plunger  168  disengages from latch dog  164  thereby allowing the biasing device  166  to return the latching arm back to the latching position (see  FIG. 6   e ). 
         [0042]      FIGS. 7   a - e  illustrate a sequence of steps that allow an operator to initially decide to remove the supplemental rod box  200 , but then decide to leave it attached and locked.  FIGS. 7   a - c  are the same as  FIGS. 6   a - c , illustrating that the latching arm  162  can be manually moved to an unlocked position illustrated in  FIG. 7   c  where the latch dog  164  has engaged the side of the plunger  168 . If the operator decides to re-latch the supplemental rod box  200 , without moving the supplemental rod box  200 , then the lever  183  can be used to rotate the latch dog  164  clock-wise as illustrated in  FIG. 7   d , until it clears the bottom end of the plunger  168 , and the latching arm  162  snaps back to the latched position illustrated in  FIG. 7   e.    
         [0043]    The latch mechanism  160  is a component of the first retention device  150  illustrated in  FIGS. 3   a  and  3   b , also including the guide pin  152 . When engaged with the flange  202  of the supplemental rod box  200 , the latch mechanism holds the supplemental rod box  200  from moving in a vertical direction relative to the primary rod box  126 . The guide pin  152 , when engaged with the aperture  204  in the flange  202 , illustrated in  FIG. 9 , holds the supplemental rod box  200  from moving in other directions. 
         [0044]    The second retention device  140  illustrated in  FIG. 4 , is shown from a different perspective in  FIGS. 10 and 12 . The rear side of the primary rod box  126  includes an upper surface  136  and the retention device  140 . The retention device includes the second guide pin  142  with an upper tapered section. This pin  142  is illustrated in greater detail in  FIG. 13 , that also shows the supplemental rod box  200  as it is being lowered to engage with the primary rod box  126 . The aperture  208  in the flange  206 , shown in  FIG. 11 , will mate with the upper portion of the guide pin  142  as shown in greater detail in  FIGS. 14   a - e .  FIG. 14   a  illustrates the flange  206  and aperture  208  as it begins to engage with the pin  142 . The flange will slide over the pin as the supplemental rod box  200  is lowered straight down as indicated in  FIGS. 14   a ,  14   b  and  14   c . At some point rod box  200  can move in direction  212  (i.e., toward the first guide pin  152 ) as allowed by the beveled catch  144  and the undercut region  243 , as shown in  FIG. 14   d . This movement is necessary to align the first guide pin  152  with aperture  204  of the flange  202 . The supplemental rod box  200  will be completely seated when it rotates counter clockwise as illustrated in  FIG. 14   e  so that it will rest on upper surface  136  defined by the top  129  of the primary rod box  126 .  FIG. 15  illustrates the shape of the aperture  208  in flange  206  as it is engaged with the guide pin  142  in the position shown in  FIG. 14   e.    
         [0045]    The supplemental rod box  200  is secured to the primary rod box  126  when the second flange  206 , with aperture  208 , is engaged with the second guide pin  142 , and the first flange  202 , with aperture  204 , is engaged with the first guide pin  152 , and the latch mechanism  160  is also engaged with the flange  202 . Each of these three connections occurs automatically, as the operator lowers the removable rod box onto the primary rod box. The overall process is depicted in  FIGS. 16   a - d , with  FIG. 16   a  showing the supplemental rod box  200  positioned above the primary rod box  126 , with the aperture  208  in flange  206  aligned with the pin  142 . The operator lowers the supplemental rod box  200  in a first direction  210 , generally straight down. Once the flange  206  contacts the upper surface  136  the supplemental rod box  200  will move in a second manner including some portion of sliding movement in a second direction  212  as illustrated in  FIG. 16   b  and in a third manner where the end  333  moves generally along an arc segment defined by a radius swung about the end  335  along the direction shown as  214  in  FIG. 16   c . The process is complete when the removable box is seated on surfaces  136  and  128 , the pins  152  and  142 , are fully engaged with the apertures  204  and  208  and the latch mechanism engages the flange  202 , as illustrated in  FIG. 16   d.    
         [0046]    Various modifications and alterations of this disclosure will become apparent to those skilled in the art without departing from the scope and spirit of this disclosure, and it should be understood that the scope of this disclosure is not to be unduly limited to the illustrative embodiments set forth herein.