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FIELD OF THE INVENTION 
   The present invention relates generally to equipment used for ground boring; more specifically to a method and apparatus associated with manipulating drill rod used in drilling; and more particularly still to a method and apparatus for indexing drill rod loading mechanisms between columns in a drill rod magazine mounted on a horizontal directional drilling machine. 
   BACKGROUND OF THE INVENTION 
   Horizontal directional drilling, commonly referred to as HDD, is a process used in a number of applications such as installing utilities underground. The HDD process, regardless of the application, includes a pilot hole-boring step. In this step a bore hole is created that extends underground—generally horizontal or parallel to the surface of the earth—starting at a launch point and ending at a termination point. 
   The bore hole is created by positioning a boring machine to rotate and push a drill string through the ground. A drill bit is attached to the leading end of the drill string. The drill string is created by connecting individual drill rods together end-to-end from a supply of drill rods stored on the boring machine. The connection between the rods is made up, and subsequently broken in a later step, by the boring machine. A typical boring machine includes a gearbox that connects to the drill string, a drill rod storage magazine, and a rod loading mechanism. The rod loading mechanism moves the individual drill rods from the storage magazine into alignment with the drill string and the gearbox where the individual drill rod is connected to and made a part of the drill string. 
   Rod loading mechanisms typically include a rod transfer mechanism that moves the rod from the storage magazine and positions the rod with one end in alignment with the drill string and the other end in alignment with the gearbox. Typically, when the drill rod is not being used as part of the drill string, it is stored in a plurality of columns within the storage magazine. In many of these systems, the drill rod is removed sequentially from the first column of the storage magazine proximal to the drill string. After the first, proximal column is emptied, then drill rod is taken from the next adjacent column. Depending on the number of drill rods required for the application, the drill rod is removed column by column until the most distal column is emptied. When the drill string is later broken down, the reverse procedure is utilized, whereby the most distal column is filled first, with next closer adjacent column filled next, and continuing until the proximal column is filled. 
   The above method is especially used with rod transfer mechanisms that employ a single rod blocking member, with a rod receiving pocket, or grip, located proximal the drill string. The rod receiving pocket may be located physically adjacent the rod blocking member or may be part of the same structure. In either event, however, if the rod receiving pocket is indexed past a column that is not yet emptied, then the drill rod from that column is unintentionally released into the drill string area. Since the drill rod is generally both long and heavy, drilling must cease until the drill rod is untangled and removed from the drill string area. This creates an inefficient and aggravating situation. 
   In order to insure that the rod transfer mechanism is properly indexed to the appropriate column, mechanical stops have been employed in the past. However, to set the stops to the correct index position, the operator needed to stop drilling, leave the operator position, move to the magazine area, and then manually set the stop. Alternatively, a second person needed to set the position. In either instance the process was inefficient. Therefore, there is a need in the art for a method and apparatus for efficiently and correctly setting the index position for the appropriate column of a drill rod magazine of an HDD machine from the operator position. The present invention overcomes the shortcomings of the prior art and addresses these needs in the art. 
   SUMMARY OF THE INVENTION 
   The present invention generally relates to a method and apparatus for properly indexing the rod transfer mechanism of an HDD machine to position the rod receiving pocket under the appropriate column of the drill rod storage magazine. Mechanical stops are utilized on the rod transfer mechanism, with the stops being offset from one another. The stops engage a moveable block which is moved by the operator using a block position selector device. 
   As the selector device is actuated, the block moves between stop positions. For each selector device position, the block is aligned with one of the stops. Further, the stops are arranged such that each stop corresponds to a respective column of the magazine. Accordingly, the rod transfer mechanism moves transversely away from the longitudinal axis of the drill string until the selected stop engages the block. In this manner, the rod receiving pocket is located beneath the appropriate column, and the column is emptied of drill rod before moving the block to the next column position. 
   The block position selector device is preferably located at the HDD machine operator&#39;s station. The selector device enables the operator to select the appropriate column of the magazine. This is accomplished functionally by the selector device arranged and configured to physically move the block in discrete increments to the appropriate positions corresponding to the offset stops. In the preferred embodiment, a cable slidably received within a jacket is employed between the position selector and the block to move the block. 
   One aspect of the invention relates to the ergonomic and positive manner in which the selector device operates. More specifically, in one preferred embodiment, the stops are offset vertically and the moveable block is spring biased toward its upward most position. This requires a force to be applied to a pivoting lever of the selector device in order to move the lever (and, correspondingly, the block) to a position other than the first column. Additionally, a first handle is included on the distal end of the lever (e.g., the end away from the pivot point of the lever) and a biased latch is attached to the lever. The biased latch includes a pin biased into engagement with one of a plurality of pockets visible within a selector window. The location of the pockets in the window provide a sure visual representation to the operator of the column from which the drill rod will be selected. Further, because the lever includes the latch, the lever cannot inadvertently move (and thus the block cannot move) to an unwanted column. 
   In operation, the operator selects the appropriate column by lifting the spring biased latch on the lever (e.g., by moving a second handle attached to the biasing latch toward the first handle at the distal end of the lever). This lifts the pin out of the current engagement pocket such that the operator can then move the lever to the desired column. Releasing the spring biased latch then lowers the pin into the newly selected pocket. As the lever is moved, the block is raised (or lowered depending on the direction of movement of the lever) so as to engage a different stop. This in turn selects the column in the magazine. 
   Therefore, according to one aspect of the invention, there is provided a drill rod handling system, comprising: a drill rod storage magazine, wherein the drill rod is stored in a plurality of columns; a rod transfer mechanism, the rod transfer mechanism including a plurality of stops, the stops being offset from one another and each of which are positioned such that the rod transfer mechanism unloads drill rod from one of the columns; and a moveable block which selectively engages one of the stops, wherein the moveable block is positioned into alignment with a stop to select drill rod from a desired column. 
   According to further aspects in accordance with the foregoing paragraph, there is provided: a mechanical linkage connected to the moveable block, the mechanical linkage moving the moveable block based on a selected position; a plurality of selection positions corresponding to the columns; and a selection lever and a biased latch, the biased latch engaging a selection position, whereby the mechanical linkage cannot move between selection positions until the biased latch activated. 
   According to another aspect of the invention, there is provided a horizontal directional drilling machine, comprising: a drill rod storage magazine having a plurality of generally vertical columns; a boring assembly defining a drill string axis comprising a rack frame with an upper end and a lower end, a gearbox configured to travel along the rack frame from the upper end to the lower end, and a vise assembly a the lower end; a drill rod transfer mechanism configured to move transversely relative to the drill string axis to receive drill pipe from the storage magazine; an operator station; a plurality of stops mounted on the drill transfer mechanism, the plurality of stops being offset from one another and each of which are positioned such that the rod transfer mechanism unloads drill rod from one of the vertical columns; and a moveable block which selectively engages one of the stops, wherein the moveable block is positioned into alignment with a stop to select drill rod from a desired vertical column. 
   According to yet another aspect of the invention, there is provided a method for selecting a desired column of a drill rod magazine having a plurality of columns, the magazine of the type utilized on a horizontal directional drilling machine where a drill rod transfer mechanism moves the drill rod from the desired column to a drill string, the method comprising: affixing a plurality of stops on the rod transfer mechanism; locating a moveable block between a number of positions, wherein one stop is engaged in each position; connecting a mechanical linkage to move the block to the desired position. 
   The invention may also be employed in other environments which utilize drill rod storage locations, columns, rows and/or magazines. For example, the principles of the present invention may be employed in connection with vertical drilling devices. Also, the invention is not limited to use with single blocking member rod transfer mechanisms. For example, the principles of the present invention may be employed with rod transfer mechanisms which can select drill rod from a desired column while blocking the remaining columns. 
   While the invention will be described with respect to preferred embodiment configurations and with respect to particular devices used therein, it will be understood that the invention is not to be construed as limited in any manner by either such configuration or components described herein. Also, while the particular types of transfer mechanisms are described herein, it will be understood that such particular mechanisms are not to be construed in a limiting manner. Instead, the principles of this invention extend to any environment in which selection of a row or column in a drill rod magazine or other drill rod storage location is desired. These and other variations of the invention will become apparent to those skilled in the art upon a more detailed description of the invention. 
   The advantages and features which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. For a better understanding of the invention, however, reference should be had to the drawings which form a part hereof and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view illustrating the basic components of a horizontal directional drill device; 
       FIG. 2  is a section view through a drill rod magazine and a portion of the HDD machine, including the drill rod transfer device; 
       FIG. 3  is an enlarged view of the drill rod transfer device illustrating the moveable block and the vertically and horizontally offset stops; 
       FIG. 4   a  is a schematic view of the block position selector device in a first position with the moveable block lowered; 
       FIG. 4   b  is a schematic view of the block position selector device in a second position with the moveable block raised; and 
       FIG. 5  is a perspective view of the lever and latch device on the block position selector device. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Reference will now be made in detail to exemplary aspects of the present invention which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like parts. 
     FIG. 1  illustrates a typical horizontal directional drill  10  including an operator console  12 , a main frame  14 , a power supply  16  (e.g., a prime mover), a rack frame  18 , a gearbox  20  that is arranged and configured to move back and forth along the longitudinal axis of the rack frame  18 . Spindle  21  can be independently rotated clockwise or counterclockwise. A rod magazine  22  located generally above and to the side of the rack frame  18  stores drill rods  28 . Pipe transfer mechanism  24  is arranged and configured to move the drill rod from the magazine  22  to a position in line with the drill string  26 . Pipe transfer mechanism  24  has an upper and a lower assembly—with one assembly located at each end of the magazine  22 . As used herein, the term lower refers to a position closer/nearer to the surface of the ground, while upper refers to a position that is relatively further from the ground. A vise assembly  30  is located proximate the lower pipe transfer mechanism  24 . Accordingly, in operation, the pipe transfer mechanisms select and transfer individual drill rod  28  from the magazine  22  and into alignment with the drill string  26  and spindle  21  of gearbox  20 . 
   It will be appreciated that the drill rod  28  is referred to herein as both drill rod and drill pipe. Such terms are used interchangeably herein and are not meant to denote a different type of work piece or structure. 
   Now turning to  FIG. 2 , one of the pipe transfer mechanisms  24 , the magazine  22 , the rack frame  18 , the spindle  21  and the gearbox  20  are illustrated. In  FIG. 2 , the pipe transfer mechanism  24  is shown positioned with the rod pocket  60  located directly beneath rod column  61   e . This column  61   e  is most distal from the drill string  26  (which is in-line with the spindle  21  in  FIG. 2 ). Column  61   a  is most proximal to the drill string  26  with each adjacent column  61   b ,  61   c , and  61   d  moving progressively further away from the drill string  26 . A plurality of stops  63   a - 63   e  are included on the pipe transfer mechanism  24 . The stops  63   a - 63   e  are arranged in a horizontal and vertical offset from one another (e.g., arranged in a pattern resembling a “stair-step”). Those of skill in the art will appreciate that other patterns and physical locations relative to one another may be used for the stops. 
   The transfer mechanism  24  includes rod pocket  60  at a first end of the mechanism, and a rod blocking member  64  extending from the rod pocket  60  to the second end of the mechanism. It will be appreciated however, that the rod blocking member  64  may be arranged and configured to other lengths in order to provide the function of blocking drill pipe  28  from exiting non-selected columns of the magazine  22 . On the lower side of the mechanism is a gear rack  66  which is engaged by a driven gear  68 . Movement of the driven gear  68  moves the transfer mechanism  64  back and forth under the magazine and transversely relative to the longitudinal axis of the drill string  26 . By driven, what is meant is that the gear is powered in a manner by which the gear rotates with enough force to move the transfer mechanism. A hydraulic fluid motor (not shown) may be used to drive the gear  68 , with the hydraulic fluid motor powered by a hydraulic pump connected to the power supply  16  (best seen in  FIG. 1 ). A pressure limiting device is preferably utilized in connection with the hydraulic pump as will be described in more detail below. The mechanism  24  is supported on the frame  14  with suitable bushings or bearings (not shown). 
   As noted above, the magazine  22  includes a plurality of columns  61   a - 61   e  in which drill rod  28  is stored when not connected to the drill string  26 . The magazine  22  may include a bar  71  at each end for lifting the magazine  22  with a front end loader, crane or other suitable lift assisting device. The bar  71  may provide additional functionality of retaining drill rods  28  within the magazine  22  if the magazine is stored on its side and/or is inadvertently placed or dropped in that position. The columns  61   a - 61   e  are formed with outer walls  68  and inner walls  70 . The drill rod  28  is generally placed within the columns  61   a - 61   e  (best seen in  FIG. 1 ), and gravity is utilized to lower the drill rod  28  within the respective columns to a position where the drill rod  28  drops into the rod pocket  60  when the particular column is selected. 
   The rod pocket  60  is preferably selected to be a distance from the bottom of the magazine  22  such that only one drill rod  28  is released from the column at a time. However, other drill rod  28  blocking mechanisms may be employed. For further details on the operation and structure of a transfer mechanism  24 , reference may be had, for example, to U.S. Pat. No. 6,814,164, to Mills et al., and titled Pipe Loading Device For A Directional Drilling Apparatus and to U.S. Pat. No. 5,556,253, to Mills et al., and titled Automatic Pipe-Loading Device, each of which are assigned to the assignee hereof. Such patents are hereby incorporated herein and made a part hereof. 
   Referring now to  FIGS. 2 and 3 , moveable block device  72  is mounted on frame  14  at flange  73 . A threaded extent is located through the flange  73  and frame  14 . One or more barrel nuts  74  secures the jacket  75  in place. A cable slides within the jacket  75  and a second end of the cable is connected to a first end of the moveable block  72 . Spring  76  applies an upward force on the moveable block  72  away from the flange  74 . The moveable block  72  is limited to reciprocating movement by bushing  77 . 
   The first end of the cable is connected to the block position selector device  100  (best seen in  FIGS. 4   a ,  4   b  and  5 ). Preferably the cable is rigid so that it can operate in both a push and pull mode. However, with use of spring  76 , the cable can be a non-rigid wire which is utilized in a pull mode. In this case, spring  76  provides the motive force for the cable to travel through the jacket in the opposition direction when desired. 
   As the cable is pulled toward the operator station (e.g., toward the block position selector device  100 ), the moveable block  72  moves downward. A second end of the moveable block is arranged and configured to engage the stops  63   a - 63   e , wherein one of the stops is engaged in any selected position. When the transfer member  24  moves away from the drill string  26  by means of the powered gear  68 , the stop  63   a - 63   e  appropriate for the selected column  61   a - 61   e  contacts the second end of the moveable block  72 . At that time, the pressure limiting device associated with the powered gear  68  causes the transfer member  24  to stop its movement. Such pressure limiting device can act to direct all hydraulic fluid away from the hydraulic fluid motor when a certain pressure is reached (e.g., when one of the stops  63   a - 63   e  engages the moveable block  72 ) and/or the pressure limiting device can shunt hydraulic fluid around the hydraulic fluid motor to limit the force the exerted. Other pressure limiting solutions may also be utilized to provide the function of limiting the force applied to the moveable block  72  by the stop  63 . 
   It will be appreciated that the selected column in  FIG. 2  is column  61   e  (e.g., the most distal column), and so stop  63   e  is illustrated as engaging the second end  73  of the moveable block  72 . In the preferred embodiment, this position of the moveable block  72  is associated with the most lowered position of the moveable block  72  and a fully compressed spring  76 . However, it will be appreciated that other positions of the moveable block  72  may be employed for the most distal column and the spring  76  may be employed in some other positions as a matter of design choice. 
     FIGS. 4   a  and  4   b  provide an end view of the transfer mechanism  24  with the moveable block  72  in a lowermost position in  FIG. 4   a  (e.g., to select column  61   e ) and an uppermost position in  FIG. 4   b  (e.g., to select column  61   a ). Also shown in  FIGS. 4   a  and  4   b  is the relative position of the lever  101  of selector device  100  when the moveable block  72  is in different positions. The selector lever  101  is engaged with pocket  102   e  in  FIG. 4   a  and is engaged with pocket  102   a  in  FIG. 4   b.    
     FIG. 5  illustrates the selector device  100  in more detail. Selector lever  101  pivots about point  104  at its first end. Handle  107  is located at second end  106 . Threaded bosses  109  and  110  are located between the first and second end of selector lever  101 . Spring biased latch device  108  is slidably mounted on selector lever  101  with bosses  109  and  110  extending through elongated channels  111  and  112 , respectively. Nuts, welded attachments or other securing devices may be utilized to retain the spring biased latch device onto selector lever  101 . Spring  113  biases the biased latch device  108  toward the second end  105  of the selector lever  101 . Spring  113  attaches between arm  114  located on the biased latch device  108  and arm  115  located on third member  116 . Third member  116  is fixed to the pivot point  104  and the second end  105  of lever arm  101 . Handle  117  is located on biased latch device  108 . Boss or pin  119  (best seen in  FIGS. 4   a  and  4   b ) is connected to biased latch device  108  and extends through an elongated channel in selector lever  101 . Pin  119  is thereby normally biased into engagement with a pocket  102   a - 102   e . However, when handle  117  is moved in a direction toward first end  106  of selector lever  101 , then the pin  119  moves out of engagement with a pocket  102 , and the selector lever  101  can be moved between pockets  102  within window  103 . Movement of the selector lever  101  moves the cable within jacket  75 . Preferably handle  117  is physically located in a location where an operator can simultaneously grasp handles  107  and  117  in order to move handle  117  closer to handle  107  against the force of spring  113 . 
   As noted above, the present invention may be employed in environments other than HDD which utilize drill rod storage locations, columns, rows and/or magazines. For example, the principles of the present invention may be employed in connection with vertical drilling devices. Accordingly, the term column is used to denote a column, row or other collection of drill rod arranged in a line. Also, the invention is not limited to use with single blocking member rod transfer mechanisms. For example, the principles of the present invention may be employed with rod transfer mechanisms which can select drill rod from a desired column while blocking the remaining columns. In this case, the columns are not necessarily emptied of drill rod in order. 
   While particular embodiments of the invention have been described with respect to its application, it will be understood by those skilled in the art that the invention is not limited by such application or embodiment or the particular components disclosed and described herein. It will be appreciated by those skilled in the art that other components that embody the principles of this invention and other applications therefor other than as described herein can be configured within the spirit and intent of this invention. The arrangement described herein is provided as only one example of an embodiment that incorporates and practices the principles of this invention. Other modifications and alterations are well within the knowledge of those skilled in the art and are to be included within the broad scope of the appended claims.

Summary:
Mechanical stops are utilized on a rod transfer mechanism, with the stops being offset vertically from one another, to index the rod transfer mechanism of an HDD machine under the appropriate column of a drill rod storage magazine. The stops engage a moveable block which is moved by the operator using a block position selector device. The stops are arranged such that each stop corresponds to a respective column of the magazine. Accordingly, the rod transfer mechanism moves transversely away from the longitudinal axis of the drill string until the selected stop engages the block. The block position selector device is preferably located at the HDD machine operator&#39;s station. A cable slidably received within a jacket is employed between the position selector and the block to raise and lower the block.