Abstract:
The cable tie tool has a modular tool head and a tool handle from which the tool head may be detached. The attachment and detachment provided by the modular tool head provides for the use of multiple tool heads with a single tool handle in which is mounted a trigger mechanism. Each modular tool head is secured to the tool handle by a latch mechanism. Each tool head further includes a tensioning mechanism for applying a tension force to a cable tie. Each tensioning mechanism provides for application of a corresponding tension force to the cable tie proportional to the force applied to the tensioning mechanism by the trigger mechanism. The respective tension forces are different for at least one uniform force applied by the trigger mechanism to the corresponding tensioning mechanisms.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application claims priority to and the benefit of U.S. Provisional Patent Application No. 60/544,362 filed in the U.S. Patent and Trademark Office (USPTO) on Feb. 13, 2004. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to a cable tie tool having a modular tool head, and more specifically, to such a tool head which may be detachably secured to the tool handle of the cable tie tool. 
     Cable ties are used to bundle or secure a group of articles such as electrical wires or cables. Cable ties of conventional construction include a cable tie head and an elongate strap extending therefrom. The strap is wrapped around a bundle of articles and thereafter inserted through a passage in the head. The head of the cable tie typically supports a locking element which extends into the head passage allowing the strap to be inserted through the passage but preventing retraction of the strap through the passage in the head. Two longitudinally separated portions of the strap are thereby secured to the head to define a loop for holding together the group of articles. 
     In use, the installer manually places the tie about the articles to be bundled, inserts the strap through the head passage and then manually tightens the tie about the bundle. Further tightening of the cable tie, which increases the tension in the strap thereof, may be provided by a cable tie tool. 
     One type of such a cable tie tool includes a housing which is generally pistol-shaped where the housing has a barrel into which the strap may be inserted for application of the tension. The housing has a grip which depends from the barrel. The tool includes a trigger mechanism having a trigger link located under the barrel and in front of the grip. The trigger link is elongate and in generally depending relation relative to the barrel such that, when the heel of the hand of a user is placed against the grip such that the fingers of the user&#39;s hand extend forwardly, the fingers may encircle the forward surface of the trigger link. Forcibly drawing the fingers toward the heel of the hand, i.e., squeezing the trigger link and grip, causes the trigger link to be displaced toward the grip. The trigger mechanism extends into the housing and is able to grasp the strap, and to apply the predetermined tension thereto in proportion to the drawing or squeezing force applied to the trigger link. 
     Cable tie tools are typically able to apply a specific range of tension forces to a cable tie where such a range is typically defined a minimum and maximum force. If the range of tension forces which a particular tool can apply does not include the force required by a particular cable tie, then a different tool would be normally be required for such a cable tie. Cable ties may be constructed in a wide variety of sizes which require an equally wide variety of force magnitudes to properly tension the cable ties. Because of the limitations in the range of forces any particular installation tool can apply to a cable tie, more than one installation tool would typically be required to apply proper tension forces to a wide variety of cable ties. Accordingly, if a wide variety of cable ties are to be used, more than one cable tie tool would normally be required. 
     The use of multiple cable tie tools has disadvantages. For example, having to carry the multiple tools is typically cumbersome. Also, having to switch from using one tool to another is normally a burden. 
     SUMMARY OF THE INVENTION 
     The cable tie tool of the present invention has a modular tool head and a tool handle from which the tool head may be detached. The attachment and detachment provided by the modular tool head provides for the use of multiple tool heads with a single tool handle in which is mounted a handle linkage. 
     Each modular tool head is secured to the tool handle by a latch mechanism. Each tool head further includes a tensioning mechanism for applying a tension force to a cable tie. Each tool head has a joint for coupling the corresponding tensioning mechanism to the trigger mechanism such that a gripping force applied to the trigger mechanism is transmitted to the corresponding tensioning mechanism. The joint provides for coupling and decoupling of the trigger and tensioning mechanisms based on the relative positions thereof. The joint facilitates coupling and decoupling of the trigger and tensioning mechanisms and, accordingly, the attachment of multiple tool heads to the tool handle, and the removal of the tool heads therefrom. Each tensioning mechanism provides for application of a corresponding tension force to the cable tie proportional to the force applied to the tensioning mechanism by the trigger mechanism. The respective tension forces are different for at least one uniform force applied by the trigger mechanism to the corresponding tensioning mechanisms. 
     The multiple tool heads thereby provide for a single tool handle to apply different tension forces to cable ties by using different tool heads with the tool handle. This provides numerous advantages. For example, when the tool handle and tool head are used to tension a cable tie, the user&#39;s hand normally grasps the tool handle, typically the grip thereof, and the hand is forcibly closed around the grip to apply tension to the cable tie. The hand of the user may continue to grasp the grip of the tool handle throughout its entire use, including during removal and reattachment of the tool heads thereto. Thus, the grasp of the tool handle by the user may continue uninterrupted while the single tool handle provides a wide range of tension forces to the cable tie by using different tool heads. Accordingly, a single tool handle may be used with a wide array of cable ties without requiring the grasp by the user of the tool handle to be released, thus substantially eliminating the burden normally associated with changing cable tie tools. 
     Also, the user may carry a single cable tie tool, including a single tool handle and multiple tool heads, and nevertheless be able to provide a wide range of tension forces by using the multiple tool heads. This wide range of tension forces enables the single tool handle, in combination with multiple tool heads, to be usable with a wide range of cable ties. This reduces the cumbersomeness which normally results from carrying multiple cable tie tools because multiple tool heads are normally significantly smaller and easier to manipulate as compared to multiple cable tie tools. 
     Methods of attaching the modular tool head of the present invention to the tool handle of the cable tie tool and removing the tool head therefrom facilitate use of a single tool handle with multiple tool heads. 
     These and other features of the invention will be more fully understood from the following description of specific embodiments of the invention taken together with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a front perspective view of the modular tool head connected to the tool handle for a cable tie tool of the present invention; 
         FIG. 2  is a rear perspective view of the modular tool head and tool handle of  FIG. 1 ; 
         FIG. 3  is a side elevation view of the modular tool head and tool handle of  FIG. 1 ; 
         FIG. 4  is a top plan view of the modular tool head and tool handle of  FIG. 3 ; 
         FIG. 5  is a front elevation view of the modular tool head and tool handle of  FIG. 3 ; 
         FIG. 6  is a cross-sectional view in the plane indicated by line  6 — 6  of  FIG. 4  showing components located within the modular tool head and the linkage located within the tool handle; 
         FIG. 7  is a cross-sectional view in the plane indicated by line  7 — 7  of  FIG. 6  showing components located within the modular tool head and tool handle; 
         FIG. 8  is an exploded view of the tool handle of  FIG. 1  showing the linkage located within the tool handle; 
         FIG. 9  is a perspective view of the trigger mechanism of  FIG. 1 ; 
         FIG. 10  is a side elevation view of the trigger mechanism of  FIG. 9 ; 
         FIG. 11  is a rear elevation view of the trigger mechanism of  FIG. 10 ; 
         FIG. 12  is a top plan view of the trigger mechanism of  FIG. 10 ; 
         FIG. 13  is a front elevation view in the plane indicated by line  13 — 13  of  FIG. 10  showing the pin which connects the rod link to the tool handle; 
         FIG. 14  is a front elevation view in the plane indicated by line  14 — 14  of  FIG. 10  showing the pin which connects the inner trigger link to the tool handle; 
         FIG. 15  is a front elevation view in the plane indicated by line  15 — 15  of  FIG. 10  showing the pin which connects the inner trigger link to the outer trigger link; 
         FIG. 16  is a perspective view of the outer trigger link of  FIG. 9 ; 
         FIG. 17  is a side elevation view of the outer trigger link of  FIG. 16 ; 
         FIG. 18  is a rear elevation view of the outer trigger link of  FIG. 17 ; 
         FIG. 19  is a top plan view of the trigger mechanism of  FIG. 17 ; 
         FIG. 20  shows a sheet from which the outer trigger link is formed; 
         FIG. 21  is an exploded view of the modular tool head of  FIG. 1 ; 
         FIG. 22  is a front perspective view of a modular tool head and an alternative second embodiment of a tool handle of a cable tie tool of the present invention; 
         FIG. 23  is a rear perspective view of the modular tool head and tool handle of  FIG. 22 ; 
         FIG. 24  is a side elevation view of the modular tool head and tool handle of  FIG. 22 ; 
         FIG. 25  is a top plan view of the modular tool head and tool handle of  FIG. 24 ; 
         FIG. 26  is a front elevation view of the modular tool head and tool handle of  FIG. 24 ; 
         FIG. 27  is a rear elevation view of the modular tool head and tool handle of  FIG. 24 ; 
         FIG. 28  is a cross-sectional view in the plane indicated by line  28 — 28  of  FIG. 25  showing components located within the modular tool head and the linkage located within the tool handle; 
         FIG. 29  is a cross-sectional view in the plane indicated by line  29 — 29  of  FIG. 28  showing components located within the modular tool head and tool handle; 
         FIG. 30  is an exploded view of the tool handle of  FIG. 22  showing the linkage located within the tool handle; 
         FIG. 31  is a rear perspective view of an alternative third embodiment of the cable tie tool of the present invention showing a modular tool head connected to a tool handle; 
         FIG. 32  is an enlarged view of the circled portion  32  of  FIG. 31  showing the latch of the tool handle for securing the tool head thereto; 
         FIG. 33  is a front perspective view of the cable tie tool of  FIG. 31  showing the modular tool head connected to the tool handle; 
         FIG. 34  is a side elevation view of the modular tool head and cable tie installation tool of  FIG. 33  showing the modular tool head connected to the tool handle, the tool handle being shown as transparent to show components within the head and handle housings; 
         FIG. 35  is cross-sectional view in the plane indicated by line  35 — 35  of  FIG. 34  showing components within the head and handle housings, including the latches in the open positions; 
         FIG. 36  is an enlarged view of the circled portion  36  of  FIG. 35  showing the one of the latches in the open position; 
         FIG. 37  is cross-sectional view in the plane indicated by line  37 — 37  of  FIG. 34  showing components within the head and handle housings, including the latches in the open positions; 
         FIG. 38  is cross-sectional view in the plane indicated by line  38 — 38  of  FIG. 34  showing components within the handle housing, including the latches in the open positions; 
         FIG. 39  is an enlarged view of the circled portion  39  of  FIG. 38  showing the pin through which the inner and outer trigger links are coupled; 
         FIG. 40  is cross-sectional view in the plane indicated by line  40 — 40  of  FIG. 34  showing the handle housing; 
         FIG. 41  is an enlarged view of the circled portion  41  of  FIG. 40  showing the engagement between the shell members of the handle housing portions including the distal end of the barrel; 
         FIG. 42  is a perspective view of the interior of one of the shell members of the handle housing including the distal end of the barrel; 
         FIG. 43  is a perspective view of the interior of the other shell member of the handle housing including the distal end of the barrel; and 
         FIGS. 44 to 51  correspond to  FIGS. 34 to 41 , except that in  FIGS. 44 to 51 , the latches are shown in the closed positions. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings and more particularly  FIGS. 1 and 2 , a cable tie tool  10  is shown for securing a cable tie to a bundle of articles, such as wires or cables. The cable tie tool  10  includes a modular tool head  12  and a tool handle  15 . 
     The tool head  12  has proximal and distal ends  20 ,  22 , and includes a tension adjustment knob  27  and other components, examples of which are disclosed in U.S. Provisional Patent Application 60/544,361 filed in the U.S. Patent and Trademark Office (USPTO) on even date herewith and entitled “Tension and Anti-Recoil Mechanism for Cable Tie Tool”, having as the inventors Joey D. Magno, Jr., Johan Tapper, Anders Fahlen, Joakin Norin, Goran Paulsson and Sven Wadling. The tool head  12  includes a rear housing ring  23  located to the rear thereof, as shown in  FIGS. 6 ,  7  and  21 . The rear housing ring  23  has a pair of diametrically opposed arms  24  each of which extends rearwardly from the rear edge of the ring. The arms  24  each have rear end portions the outer surfaces of which have hook formations  25  thereon. The outer surface of the rear end of each hook formation  25  is chamfered, as shown in  FIGS. 7 and 21 . Examples of components which may be included in the tool head  12  are also disclosed in U.S. Pat. No. 5,915,425 issued Jun. 29, 1999. 
     The tool handle  15  includes a handle housing  32  having pistol-shape and a longitudinal central plane  35 . The handle housing  32  includes a grip  37  which depends from a barrel  40 . Mounted on the inner surface of the handle housing  32  within the grip  37  is a trigger stop  42  which is oriented such that the longitudinal axis of the stop is generally perpendicular to the central plane  35 , as shown in  FIG. 6 . The barrel  40  has a distal end  45  and a longitudinal cylindrical passage  47  which terminates at an opening  50  which coincides with the distal end. The handle housing  32  may be formed from a pair of shell members  33  which are generally symmetrical relative to the central plane  35 . 
     Corresponding indicator tabs  41  extend longitudinally from the portions of the respective shell members  33  which form the distal end  45  of the barrel  40 . When the shell members  33  are joined together, the indicator tabs  41  define a semicircular recess  43  which locates the direction along which the tension setting number of the tool head  12  may be viewed. 
     The tool handle  15  includes a pair of latch mechanisms  65  each of which includes a lever  66  and a latch edge  68 . Each of the latch edges  68  is generally vertical and faces the front end of a respective lever  66  in adjacent relation thereto. Each of the levers  66  has a longitudinal orientation and has a rear end which is integral with the barrel  40  of a respective shell member  33 , as shown in  FIG. 7 . Each of the levers  66  and shell members  33  are formed of resilient material, such as plastic. The resiliency, for example at the junction between each lever  66  and the adjoining shell member  33 , provides for outward deflection of each lever away from the adjoining shell member upon application to the respective lever of an outward deflection force which is generally transverse to the barrel  40 . Removal of the deflection force from the levers  66  results in the levers returning to the neutral closed positions shown in  FIGS. 1 and 7 . 
     When the tool head  12 , including the proximal end  20 , is fully inserted in the passage  47  of the barrel  40 , and the levers  66  are in the neutral closed positions, the hook formations  25  of the rear housing ring  23  engage the adjacent latch edges  68 , as shown in  FIG. 7 , to prevent removal of the tool head from the barrel  40 . Full insertion of the tool head  12  into the passage  47  of the barrel  40  results in the proximal end  20  of the tool head being longitudinally to the rear of the distal end  45  of the barrel, as shown in  FIG. 6 . 
     During rearward insertion of the tool head  12  into the passage  47  of the barrel  40 , the hook formations  25  engage the inner surfaces of the portions of the shell members  33  which define the barrel  40 . Such engagement causes the arms  24  of the rear housing ring  23  to deflect inwardly as a result of the chamfer of each hook formation  25  and the stiffness of the portions of the shell members  33  engaged by the hook formations. Continued rearward insertion of the tool head  12  into the passage  47  results that hook formations  25  becoming longitudinally positioned to the rear of the adjacent latch edges  68 . This results in the arms  24  deflecting outward to the positions shown in  FIG. 7  in which the hook formations  25  engage the adjacent latch edges  68 . 
     Disengagement of the hook formations  25  from the latch edges  68  is provided by application of an inwardly directed force to each of the levers  66 . Such a force causes the each of the levers  66  to inwardly deflect the adjacent arm  24  such that the corresponding hook formation  25  is displaced inwardly a sufficient distance to clear the adjacent latch edge  68 . This removes the obstruction to forward displacement of the tool head  12  provided by the engagement between the hook formations and the corresponding latch edges  68 . As result, the tool head  12  may be displaced forwardly for removal from the barrel  40 . 
     The tool handle  15  includes a trigger mechanism  92  having a trigger linkage  95  with a pair of elongate inner trigger links  97 , as shown in  FIGS. 6 and 8 . The inner trigger links  97  each have a lower end which is pivotally connected to the grip  37  by a transverse pin  100  generally adjacent to the distal end thereof as shown in  FIG. 6 . The pin  100  may be formed of steel material. Each of the inner trigger links  97  has a longitudinal axis  102  which is generally parallel to the central plane  35 , as shown in  FIG. 27 . The inner trigger links  97  each have an upper end through which extends a transverse pin  105 , which may be formed of steel material. 
     The inner trigger links  97  each have an intermediate segment  107  between a lower segment  109  and an angled upper segment  112 , as shown in  FIG. 8 . The intermediate segment  107  is inclined relative to the lower segment  109  and relative to the lower portion of the upper segment  112 . This, and the angular shape of the upper segment  112 , results in the intermediate segment  107  being forward of an inner axis  114  which intersects the pins  100 ,  105 , as shown in  FIG. 6 . Each inner axis  114  is generally parallel to the central plane  35 . The pivotal connections between the inner trigger links  97  and grip provided by the pin  100  enables pivoting of the inner trigger links in the directions  117 ,  119  toward open and closed positions, respectively. 
     The cable tie tool  10  includes an outer trigger link  122  having a pair of upwardly extending arm portions  124  each of which is pivotally connected to the pin  105  such that the outer trigger link is pivotally connected to the inner trigger links  97 . The outer trigger link  122  is a one-piece structure illustrated in  FIGS. 16 to 20 , and may be formed of steel material. The outer trigger link  122  includes a grip portion  127  having a U-shaped cross-section, as viewed in  FIG. 19 , depending from the arm portions  124  in integral relation therewith. The grip portion  127  has a longitudinal axis  129  which is generally contained in the central plane  35 , as shown in  FIGS. 11 and 12 . The outer trigger link  122  is formed from a sheet, as shown in  FIG. 20 , which is formed of a deformable material such as metal. The outer trigger link  122  has a pair of shoulder portions  132  extending forwardly from the grip portion  127  at generally the same elevation as the lower ends of the arm portions  124 . 
     The pivotal connections between the inner and outer trigger links  97 ,  122  provided by the pin  105  provides for the outer trigger link to pivot in the directions  134 ,  137  toward open and closed positions, respectively. 
     The trigger mechanism  92  includes an intermediate linkage  139  having an elongate rod link  142 , as shown in  FIGS. 8 and 9 . The lower end of the rod link  142  is pivotally connected to the grip  37  by a transverse pin  144  generally adjacent to the distal end thereof, as shown in  FIG. 6 . The pin  144  may be formed of steel material. The rod link  142  has a longitudinal axis  147  which is generally contained in the central plane  35 , as shown in  FIG. 12 . 
     The pivotal connection provided by the pin  144  enables pivoting of the rod link  142  in the directions  149 ,  152  toward open and closed positions, respectively. Sufficient pivoting of the rod link  142  in the direction  149  results in the engagement of the rod link with the trigger stop  42  thereby providing a limit to such pivoting, as shown in  FIG. 6 . 
     The upper portion of the rod link  142  extends into the barrel  40 . The upper end of the rod link  142  has a detent  154  which extends to an axially-reciprocating pull rod  157  of a tensioning mechanism located in the tool head  12 , as shown in  FIG. 7 . The pull rod  157  has a proximal end  159  including a pull rod yoke  162  having a transverse yoke web  163  and a pair of yoke flanges  164  extending outwardly from the yoke web. The rear of pull rod yoke  162  is closed by a pull rod pin  165  which extends between the yoke flanges  164 . The detent  154  is inserted within the pull rod yoke  162  so that the detent is forward of the pull rod pin  165  and thereby longitudinally fixed relative to the pull rod  157 , as shown in  FIG. 6 . Accordingly, the pull rod  157  is axially displaced relative to the tool head  12  when the rod link  142  is pivoted in the directions  149 ,  152 . 
     The intermediate linkage  139  further comprises a pair of central links  167 , a pair of inner links  169 , and an outer link  172 , as shown in  FIGS. 6 and 8 . The respective central, inner and outer links  167 ,  169 ,  172  each have an end which is pivotally connected to an end of the other links at a transverse pin  174  such that the links have a generally Y-shaped configuration when the inner and outer trigger links  97 ,  122  are each in the respective positions shown in  FIGS. 6 and 10 . The pin  174  is flushed relative to the outer lateral surfaces of the inner trigger links  97 . 
     The central links  167  each have a longitudinal axis  177  which is generally parallel to the central plane  35 , as shown in  FIG. 12 . The inner links  169  each have a longitudinal axis  179  which is generally parallel to the central plane  35 . The outer link  172  has a longitudinal axis  182  which is generally contained in the central plane  35 . 
     The central links  167  each have an end opposite to the pin  174  which is pivotally connected to a respective one of the inner trigger links  97  by a transverse pin  175  which is flushed relative to the outer lateral surfaces of the inner trigger links  97 . The inner links  169  each have an end opposite to the pin  174  which is pivotally connected to the rod link  142  by a transverse pin  176  which is flushed relative to the outer lateral surfaces of the inner links  169 . The outer link  172  has an end opposite to the pin  174  which is pivotally connected to the outer trigger link  122  by a transverse pin  184  which is supported in the shoulder portions  132 . The pin  184  is flushed relative to the outer lateral surfaces of the outer trigger link  122 . 
     A transverse pin  185  is fixed to each of the inner trigger links  97 . Each pin  185  is engaged by a recessed portion  187  of a respective central link  167  to limit rotation of the central link in the direction  188  relative to the corresponding inner trigger link  97 . The pin  185  is flushed relative to the outer lateral surfaces of the inner trigger links  97 . 
     In operation, the inner and outer trigger links  97 ,  122  are pivoted in the directions  117 ,  134  to the respective open positions. The strap of the cable tie is then secured to the pawl grip  187  of the tool head  12 . 
     The user grasps the outer trigger link  122  and grip  37  of the handle housing  32  such that the fingers of the user&#39;s hand partially encircle the trigger link and the heel of the user&#39;s hand abuts the grip. The fingers are oriented along the outer trigger link  122  so that the larger fingers are between the smaller fingers and the barrel  40 . 
     The user&#39;s hand is then closed causing the outer trigger link  122  to pivot in the direction  137  toward the closed position. Such pivoting of the outer trigger link  122  in the direction  137  produces a reverse sequential pivoting of the outer and inner trigger links  122 ,  97  as a result of the shape and size of the outer and inner trigger links and central, inner and outer links  167 ,  169 ,  172 . This reverse sequential pivoting causes the displacement to produce an initial pivoting of the outer trigger link  122  relative to the inner trigger links  97  in an initial direction toward the closed position. This initial direction is the pivoting direction  137  of the outer trigger link  122  relative to the inner trigger links  97  about the pin  105 . During the initial pivoting of the outer trigger link  122 , pivoting of the inner trigger links  97  relative to the grip  37  is substantially limited. The initial pivoting causes pivoting of the central, inner and outer links  167 ,  169 ,  172  which, in turn, causes the rod link  142  to pivot in the direction  152  toward the closed position. The pivoting of the rod link  142  in the direction  152  toward the closed position produces axial displacement of the pull rod  157  in the proximal direction which, because of its coupling to the pawl grip  187 , applies a tensile force to the cable tie. 
     The reverse sequential pivoting provides for continued displacement of the outer trigger link  122  toward the grip  37  to cause subsequent pivoting of the inner trigger links  97  relative to the grip in a subsequent direction toward the closed position. The subsequent pivoting is initiated when the outer trigger link  122  reaches the limit at which continued pivoting of the outer trigger link in the initial direction is substantially prevented. The subsequent direction is opposite from the initial direction, and is the pivoting direction  119  of the inner trigger links  97  relative to the grip  37  about the pin  100 . During the subsequent pivoting, pivoting of the outer trigger link  122  relative to the inner trigger links  97  is substantially limited. The subsequent pivoting also causes pivoting of the central, inner and outer links  167 ,  169 ,  172  which, in turn, cause the rod link  142  to pivot further in the direction  152  toward the closed position. The further pivoting of the rod link  142  toward the closed position produces further axial displacement of the pull rod  157  in the proximal direction to apply a further tensile force to the cable tie. 
     The reverse sequential pivoting, including the initial and subsequent pivoting of the inner and outer trigger links  97 ,  122 , causes the central, inner and outer links  167 ,  169 ,  172  to pivot. Additional disclosure of this reverse sequential pivoting is contained in U.S. patent application Ser. No. 10/614,435 filed in the USPTO on Jul. 7, 2003. 
     The tool head  12  may be removed from the tool handle  15  by pivoting the outer trigger link  122  in the direction  134  toward the open position, which causes the inner trigger links  97  to pivot in the direction  117  toward the open position. This, in turn, causes the rod link  142  to pivot in the direction  149  toward the open position into engagement with the trigger stop  42 , as shown in  FIG. 6 . 
     Pivoting of the rod link  142  causes the detent  154  to drop below so as to clear the pull rod pin  165  such that the rod link is decoupled from the pull rod  157 . In contrast, the coupling between the detent  154 , pull rod yoke  162  and pull rod pin  165 , shown in  FIG. 6 , obstructs removal of the tool head  12  from the tool handle  15 . Thus, pivoting the rod link  142  in the direction  119 , and deflecting the levers  66  inwardly a sufficient distance to cause the hook formations  25  to clear the adjacent latch edges  68 , allows removal of the tool head  12  from the tool handle  15 . 
     When the tool head  12  is removed from the tool handle  15 , the engagement of the rod link  142  with the trigger stop  42  obstructs further pivoting of the rod link in the direction  149 . This engagement of the rod link  142  with the trigger stop  42 , in combination with the connections of the central, inner and outer links  167 ,  169 ,  172  to the inner and outer trigger links  97 ,  122  prevents the rod link and inner and outer trigger links from pivoting substantially beyond the angular positions thereof relative to the tool handle  15  when the tool head  12  is removed from the tool handle  15 . 
     The tool head  12  may be inserted into the tool handle  15  by pivoting the outer and inner trigger links  122 ,  97  in the directions  134 ,  117  such that the rod link  142  pivots in the direction  149  into engagement with the trigger stop  42 . Insertion of the tool head  12  into the passage  47  is toward the left, as shown in  FIG. 6 , and may be for a longitudinal distance of 10 mm. The insertion of the proximal end  20  is continued sufficiently so that the yoke web  163  of the pull rod yoke  162  engages the detent  154  of the rod link  142 . Insertion of the proximal end  20  is continued causing the yoke web  163  to displace the detent  154  in the rearward direction causing rod link  142  to pivot in the direction  152  toward the closed position. As a result, the detent  154  is translated upwardly within the pull rod yoke  162  between the yoke web  163  and pull rod pin  165 , as shown in  FIG. 6 . The detent  154 , pull rod yoke  162  and pull rod pin  165  thereby define a joint which provides for coupling and decoupling of the trigger mechanism  92 , which includes the rod link  142 , and the tensioning mechanism, which includes the pull rod  157 , based on the relative positions thereof. 
     The insertion of the tool head  12  rearward through the passage  47  results in the hook formations  25 , including the chamfered portions thereof, engaging the inner surfaces of the portions of the shell members  33  which define the barrel  40 . When the tool head  12  is sufficiently inserted into the barrel  40 , the hook formations  25  clear the adjacent latch edges  68  causing outward deflection of the arms  24 . This causes the hook formations  25  to engage the adjacent latch edges  68 , as shown in  FIG. 7 , thereby to prevent removal of the tool head  12  from the barrel  40 . 
     Alternative embodiments of the tool head  12  are possible in which the components thereof are generally heavier and stronger such that the tension force applied to the cable tie by the tool head is larger using the same tool handle  15  as is shown in  FIGS. 1 and 2 . For example, the tool head  12  illustrated in  FIGS. 1 and 2  may provide for the application of tensile forces in the range of 18 to 50 lbs. to the cable tie. In contrast, an alternative embodiment of the tool head may provide for the application of tensile forces in the range of 50 to 120 lbs. to the cable tie. 
     An alternative embodiment of the cable tie tool  10   a  is shown in  FIGS. 22 to 30 .  FIGS. 22 to 26 , and  28  to  30  are views which correspond to the views of  FIGS. 1 to 8 , respectively. Parts shown in  FIGS. 22 to 30  which correspond to parts shown in  FIGS. 1 to 21  have the same reference numeral as in  FIGS. 1 to 21  with the addition of the suffix “a” in  FIGS. 22 to 30 . The tool head  12   a  is generally the same as the tool head  12  shown in  FIGS. 1 to 21 . The tool handle  15   a  shown in  FIGS. 24 to 30  includes a trigger mechanism  191  as shown in  FIGS. 28 and 30 . 
     An alternative embodiment for the tool head  12   b  and tool handle  15   b  is shown in  FIGS. 31 to 51 . Parts shown in  FIGS. 31 to 51  which correspond to parts shown in  FIGS. 1 to 21  have the same reference numeral as in  FIGS. 1 to 21  with the addition of the suffix “b” in  FIGS. 31 to 51 . 
     The tool head  12   b  includes a tensioning mechanism having a tension adjustment knob  27  the outer surface of which has a circular groove  30  generally adjacent to the proximal end thereof, as shown in  FIGS. 35 and 36 . The circular groove  30  is contained in a plane which is generally transverse to the longitudinal axis of the tool head  12   b.    
     The portions of the shell members  33   b  which form the distal end  45   b  of the barrel  40   b  are secured together by an upper hook flange  34  which is inserted into a corresponding upper catch flange  36 , shown in  FIGS. 42 and 43 . The upper hook and catch flanges  34 ,  36  facilitate the connection of upper portions of the shell members  33   b  without requiring a connecting screw or similar fastener. These portions of the shell members  33   b  are further secured together by inner and outer tab flanges  38 ,  39  which depend from the lower portion of the distal end  45   b.  The inner and outer tab flanges  38 ,  39  are secured together by a connecting screw. The shell members  33   b  are assembled by first connecting the upper hook and catch flanges  34 ,  36 , and then bringing together the inner and outer tab flanges  38   b,    39   b  for connection by inserting the connecting screw through the passages therein. 
     Formed on the inner surface of each shell member  33   b  within the barrel  40   b  is an elongate track  52  defined by a rim  53  having a generally elliptical shape. The track  52  has front and rear ends  55 ,  57 . Contained within each of the tracks  52  is a corresponding end of the pin  105   b.  The pin  105   b  extends through the upper ends of the inner trigger links  97   b.    
     The barrel  40   b  has a pair of generally elongate longitudinal cutouts  60  on opposite sides thereof generally adjacent to the distal end  45   b.  The periphery of each cutout  60  has a proximal portion defined by a rim  62  which extends radially outward from the outer curved surface of the barrel  40   b.  The inner edge of each rim  62  has a curvature which matches the curvature of the barrel  40   b.  The outer edge of each rim  62  is contained in a plane which is generally parallel to the central plane  35   b.    
     The tool handle  15   b  includes a pair of latches  65   b  each of which has a latch body  70  which is supported in a respective cutout  60  by a latch pin  67 , as shown in  FIGS. 32 ,  42  and  43 . Each latch pin  67  extends through a passage  72  in the respective latch body  70 . Each passage  72  is generally perpendicular to upper and lower edges of the respective latch body  70 , as shown in  FIGS. 34 to 36 . When each latch  65   b  is supported in a respective cutout  60 , the axis of the associated latch pin  67  is generally vertical relative to the upper and lower surfaces of the barrel  40   b.    
     Each latch  65   b  has a periphery which corresponds to the periphery of the respective cutout  60  such that, when the latch is supported in the respective cutout, the periphery of the latch is generally adjacent to the periphery of the cutout. The portion of each latch body  70  in generally proximal relation to the passage  72  constitutes a proximal portion  75  of the latch body. The outer surface of each proximal portion  75  is generally flat, as shown in  FIG. 32 . Each proximal portion  75  adjoins the portion of the cutout  60  having the rim  62  which provides the outer curved surface of the barrel  40   b  with a flat portion with which the outer surface of the proximal portion may have an even relation. The inner surface of each proximal portion  75  has a curvature which matches the curvature of the inner surface of the barrel  40   b.    
     The portion of each latch  65   b  in generally distal relation to the passage  72  constitutes a distal portion  77 . The inner and outer surfaces of each distal portion  77  have a curvature which generally matches the curvature of the barrel  40   b,  as shown in  FIGS. 32 and 37 . Extending inwardly from the inner surface of each distal portion  77  generally adjacent to the distal ends thereof is a lip  80 , the central plane of which is generally perpendicular to the central plane  35   b.  The inner and outer edges of each lip  80  have a curvature which generally matches the curvature of the distal portion  77 . 
     The connection of the latches  65   b  to the barrel  40   b  enables each latch to pivot between open and closed positions  82 ,  85 , as shown in  FIGS. 36 and 46 . When each latch  65   b  is in the open position  82 , the proximal portion  75  of the latch body  70  is displaced inward toward the barrel  40   b  causing the distal portion  77  to pivot outwardly away from the barrel. Such inward displacement of the proximal portion  75  is resisted by a spring  87  supported on an inner shoulder  90  of the barrel  40   b  such that the spring is between the shoulder and latch, as shown in  FIG. 36 . 
     When the tool head  12   b,  including the proximal end  20 , is fully inserted in the passage  47   b  of the barrel  40   b,  the circular groove  30  is longitudinally aligned with the lip  80 . This alignment enables the lip  80 , when displaced to the closed position  82  by the spring  87 , to fit in an arcuate segment of the circular groove  30 , as shown in  FIG. 46 . This fit of the lip  80  in the groove  30  prevents removal of the tool head  12   b  from the barrel  40   b.  Full insertion of the tool head  12   b  into the passage  47   b  of the barrel  40   b  results in the proximal end  20   b  of the tool head being longitudinally to the rear of the distal end  45   b  of the barrel, as shown in  FIG. 34 . 
     The pivotal connections between the inner and outer trigger links  97   b,    122   b  provided by the pin  105   b  provides for the outer trigger link to pivot in the directions  134   b,    137   b  toward open and closed positions, respectively. The ends of the pin  105   b  are contained within the corresponding rims  53  of the tracks  52  such that pivoting of the inner trigger links  97   b  in the directions  117   b,    119   b  causes the pin  105   b  to translate longitudinally within the track. When the inner trigger links  97   b  are pivoted in the direction  117   b  to the open position, the pin  105   b  approaches the front end  55  of the track  52  but does not reach it resulting in a longitudinal clearance between the pin  105   b  and the front end  55 . When the inner trigger links  97   b  are pivoted in the direction  119   b  to the closed position, the pin  105   b  approaches the rear end  57  of the track  52  but does not reach it resulting in a longitudinal clearance between the pin  105   b  and the rear end  57 . The lateral clearances between the ends of the pin  105   b  and the portion of the handle housing  32   b  contained within the rim  53  is sufficiently limited to limit any lateral deflection of the upper ends of the inner and outer trigger links  97   b,    122   b  which may result from the cantilevered support of these links by the pin  100   b.    
     Pivoting the rod link  142   b  in the direction  119   b  and pivoting the latches  65   b  to the open positions  82 , against the resistance of the respective springs  87 , allows removal of the tool head  12   b  from the tool handle  15   b.    
     The tool head  12   b  may be inserted into the tool handle  15   b  by pivoting the outer and inner trigger links  122   b,    97   b  in the directions  134   b,    117   b  such that the rod link  142   b  pivots in the direction  149   b  into engagement with the trigger stop  42   b.  The latches  65   b  are pivoted to the open positions  82  against the resistance of the springs  87 . 
     When the tool head  12   b  is fully inserted into the tool handle  15   b,  the latches  65   b  are released allowing forcible pivoting thereof by the springs  87  to the respective closed positions  85  shown in  FIG. 46 . This causes the lips  80   b  of the latches  65   b  to fit into a respective arcuate segment of the circular groove  30 , as shown in  FIG. 46 , thereby to mount and retain the tool head  12   b  to the handle housing  32   b.    
     The entire disclosure of U.S. Pat. No. 5,915,425 issued Jun. 29, 1999 is hereby incorporated by reference herein. The entire disclosures of U.S. patent application Ser. No. 10/614,435 filed in the USPTO on Jul. 7, 2003, U.S. patent application Ser. No. 29/185,985 filed in the USPTO on Jul. 7, 2003 and U.S. patent application Ser. No. 29/185,986 filed in the USPTO on Jul. 7, 2003 are each hereby incorporated by reference herein. The entire disclosures of U.S. Provisional Patent Application No. 60/544,361 filed in the USPTO on Feb. 13, 2004, U.S. Provisional Patent Application No. 60/544,362 filed in the USPTO on Feb. 13, 2004, and U.S. Provisional Patent Application No. 60/544,472 filed in the USPTO on Feb. 13, 2004 are each hereby incorporated by reference herein. The entire disclosure of the U.S. Patent application Ser. No. 11/056,078, filed in the USPTO on even date herewith and entitled “Tension and Anti-Recoil Mechanism for Cable Tie Tool”, having as the inventors Joey D. Magno, Jr., Johan Tapper, Anders Fahlen, Joakin Norin, Goran Paulsson and Sven Wadling, and is hereby incorporated by reference herein. The entire disclosure of the U.S. patent application Ser. No. 11/055,938, filed in the USPTO on even date herewith and entitled “Cycle Counter for Cable Tie Tool”, having as the inventor Joey D. Magno, Jr., is hereby incorporated by reference herein. 
     While the invention has been described by reference to certain preferred embodiments, it should be understood that numerous changes could be made within the spirit and scope of the inventive concept described. Accordingly, it is intended that the invention not be limited to the disclosed embodiments, but that it have the full scope permitted by the language of the following claims.