Abstract:
A latching mechanism ( 26 ) for an adjustable squeeze-off clamp ( 10 ) comprising a static jaw ( 16 ), a movable jaw ( 18 ) with an associated adjustment member ( 20 ) and an over-the-center operating linkage including an operating handle ( 23 ) and a link ( 24 ). The latching mechanism is selectively automatic whereby, when the lock mode is selected and the clamp is then closed, it automatically locks. The latch mechanism includes a spring ( 32 ) and a latch bar ( 28 ) with pivotal mounting ( 30 ) and notched end ( 36 ). In at least one embodiment, the latching mechanism includes an eccentric knob ( 42 ) for selection of the automatic locking mode.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to clamping devices, and more particularly, to a pliers-type clamp with a lock or latch feature. Even more particularly, the present invention relates to a lock or latch feature for use with the squeeze-off clamp disclosed in U.S. Pat. No. 5,152,497 (the &#39;497 patent), the disclosure of which patent is incorporated herein by reference. 
     The adjustable clamp of the present invention comprises a first jaw and handle, a second jaw movably connected to the first jaw, an operating linkage connected to the jaws, including a operating handle and a link, for moving the second jaw in response to the operation of the linkage, an adjustment mechanism associated with one of the jaws for changing the force exerted on a workpiece when the clamp is fully closed, and an automatic latch mechanism. The clamp is an over-the-center clamp, wherein the closing of the handles brings the linkage, particularly the link, over center. 
     The latch mechanism is operably associated with the operating linkage and provides the advantage of selectively, automatically locking the clamp closed after the clamp reaches its closed position. The latch mechanism requires a deliberate, selective choice to set it in its unlocked or nonlock mode in order to open the clamp from its closed position once it is latched, thereby preventing the inadvertent opening of the clamp. 
     The automatic latch mechanism of the present invention does not add undue complexity or weight to the clamp of the &#39;497 patent. 
     Other features and advantages of the latching mechanism of the present invention will become more fully apparent and understood with reference to the following description and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an elevation of the clamp with latching mechanism of the present invention. 
     FIG. 2 is a perspective view of the present invention, with extended clamp handles for working in deep trenches or ditches. 
     FIG. 3 is an elevational view of the present invention, particularly the latch mechanism, in one functional position. 
     FIG. 4 is a perspective of the present invention depicting the latch mechanism in another position, namely, in an unlocked setting. 
     FIG. 5 depicts the latch mechanism of the present invention in an unlocked setting with the clamp open. 
     FIG. 6 is an elevational view of the latch mechanism in an unlocked setting with the clamp closed, but unlocked. 
     FIG. 7 is a sectional view taken along line  7 — 7  of FIG.  6 . 
     FIG. 8 is an elevational view depicting another embodiment of the present invention, wherein a spring-loaded ball/detent arrangement is carried in a handle for setting the clamp in its locked and unlocked modes. 
     FIG. 9 is a sectional view taken along line  9 — 9  of FIG.  8 . 
     FIG. 10 is an elevational view of another embodiment of the present invention in one operational mode. 
     FIG. 11 is an elevational view of the embodiment depicted in FIG. 10 in another operational mode. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The Figures depict the squeeze-off clamp with latching mechanism of the present invention, and features and components thereof. With regard to means for fastening, mounting, attaching or connecting the components of the present invention to form the clamp with latch mechanism as a whole, unless specifically described otherwise such means are intended to encompass conventional fasteners such as machine screws, machine threads, snap rings, rivets, nuts and bolts, toggles, pins and the like. Components may also be connected by welding or deformation, if appropriate. Unless specifically otherwise disclosed or taught, materials for making components of the present invention are selected from appropriate materials such as aluminum, steel, metallic alloys and the like, and appropriate manufacturing or production methods including casting, extruding, molding and machining may be used. 
     Any references to front and back, right and left, top and bottom, upper and lower, and horizontal and vertical are intended for convenience of description, not to limit the present invention or its components to any one positional or spacial orientation. Such terms are to be read and understood with their conventional meanings. 
     Referring then to the Figures, particularly FIGS. 1 and 2, the clamp  10  of the present invention has a jaw or work piece gripping end  12  and a handle end  14 . The clamp  10  includes a static top jaw  16  with an integral handle  17 , a movable bottom jaw  18  and an operating linkage  22 , including a handle  23  and a link  24 , operably coupling the jaws. The bottom jaw includes a barrel-like adjustment member  20 . The clamp  10  is provided with an automatic latch mechanism  26 . 
     Referring to FIG. 1, the latch mechanism  26  is carried by the clamp top handle  23 , part of the operating linkage  22 . The latch mechanism includes a latch bar  28 , which is pivotally pinned to the handle  23  by a pin  30 . The bar  28  is an elongated, generally rectangular, solid single piece of material. Approximately mid-way along its length, adjacent to the pin  30 , it carries a latch bar spring  32  held in place by a latch spring pin  34 . Alternatively, the spring could be carried in a similar fashion by the link  24 . Adjacent one end  31 , the latch bar  28  includes a relieved notch  36  forming a latch hook for releaseably engaging an outstanding latch post  38  carried by the top jaw  16 . 
     The latch mechanism  26  also includes a function and indicator operating knob  42  which is pinned to the handle  23  by a pin  44 . Referring to FIG. 7, the knob  42  houses a spring biased pin  47  (FIG. 7) which extends from the underside thereof and selectively lodges or is received in one of the latch detents  48 ,  50  depending on the selected position of the knob  42 . The knob  42  pivots around the pin  44  and is held in either the locked or unlocked position by the engagement of the knob spring pin  47  with one of the detents  48 ,  50 , depending upon the position of the knob  42 . This causes the knob  42  to be held in the appropriate position for the mode of clamp operation as explained below. 
     FIG. 8 depicts another embodiment of the present invention, wherein a spring-loaded ball/detent arrangement  60  is carried in handle  23  for setting the clamp in its locked and unlocked modes. Referring to FIG. 9, the pin  44  for the knob  42  is replaced by a shaft  62 . The shaft  62  may be integral with the knob  42  or the knob may be fixed to the shaft. The shaft  62  includes a detent bore  64  to provide two detents  66 ,  68 , 180 degrees apart on the shaft, one for holding the knob  42  in its locked setting and the other for holding the knob  42  in its unlock setting. The handle  23  is bored to receive a ball  70 , spring  72  and set screw  74 . Two superficial detents (not shown) may be used on the shaft  62  rather than a throughbore. 
     Another alternative feature of the present invention is depicted in FIG.  6 . One of the handles  17 ,  23 , in the depicted instance handle  23 , includes a threaded bore for receiving a set screw  75  for adjusting the clamp closure and over-the-center locking by adjusting or varying the amount the handles can be brought together. The further the screw  75  is screwed in, the closer together the handles  17 ,  23  can come, and the farther over-the-center the link  24  can be moved, and the converse. This feature provides a fine tuning of the degree of over-the-center travel in the linkage, particularly of the link  24 . 
     The operation of the latching mechanism  26  of the present invention can be appreciated by consideration of the remaining drawings which depict the present invention in various operational settings or positions. Referring to FIG. 1, the jaws of the clamp  10  are depicted in a nearly fully open position with the locking knob  42  in its lock setting. In this position, the latch bar  28  is free to pivot about the pin  30  holding it to the handle  23 . The length of the latch bar  28  is specifically chosen to permit the upper region  29  of the bar to contact or ride against the end curved portion  25  of the link  24 , and to prevent it from rotating or falling downwardly against the side of the link  24  which would cause the clamp  10  to jam in the open position. 
     As the handles  17 ,  23  are moved toward each other, the jaws  16 ,  18  close. The latch bar  28  remains free to pivot between the latch knob  42  and the link  24 . The knob  42  is specifically located on the operating handle  23  to prevent the bar  28  from pivoting into position in which the bottom end  31  could jam against the post  38 . Referring to FIG. 3, the latch mechanism  26  is still in the lock setting and the clamp handles are almost closed. As the handles are brought together, the bottom end or region  31  of the latch bar  28  is free to pivot into a position in which the lower portion of the bar  28  between the end  31  and the notch  36  rides smoothly against the latch post  38  as the handles close. Even in the position depicted in FIG. 3, the latch bar  28  can still pivot away from the post  38  and avoid capturing it. 
     Referring to FIG. 2, the latch mechanism  26  of the present invention is depicted in its locked position wherein the clamp handles  17 ,  23  and jaws  16 ,  18  are closed and locked. Note that as the top handle  23  and the bottom handle  17  are brought together and the clamp  10  enters its closed position, the side of the link  24  contacts and exerts force on the latch bar spring pin  34  and the spring  32 . The spring  32  causes the latch bar  28  to pivot so that the lower portion of the latch bar  28  comes into contact against the post  38 . As the handles are closed, the link  24  continues to put pressure on the spring  32 , keeping the lower part of the bar  28  against the post  38 . When the handles are completely closed, the bar  28  is driven sufficiently so the notch  36  receives the post  38 . The latch bar  28  is held in position with the notch  36  around the post  38  due to the force created by the link  24  compressing the spring  32 , thereby locking the handles together. 
     Referring to FIGS. 4-6, initially FIG. 6, the clamp  10  and latch mechanism  26  of the present invention is depicted in its unlocked setting with the clamp handles  17 ,  23  nearly closed, but unlocked in order to open the clamp  10 . To open the clamp  10  (from the locked position depicted in FIG.  2 ), the knob  42  is rotated from its locked position to the unlocked position shown in FIG.  6 . When the knob  42  is moved to the unlock position, the knob  42  bears against the upper end of the latch bar  28 , further compressing the latch bar spring  32 , pivoting the bar  28  and causing the notch  36  to disengage from the post  38 . The handles can then be moved apart and, as they are, the link  24  moves away from the latch bar spring (i.e., from the position depicted in FIG. 4 to the position depicted in FIG.  6 ). When the link has moved sufficiently, the spring will no longer be compressed. The latch bar  28  remains free from the post  38  because, in its unlock position, the knob  42  prevents the bar  28  from pivoting sufficiently for the notch  36  to engage the post  38 . 
     FIG. 5 depicts the clamp  10  in its fully open position and in an unlocked setting. The bar  28  is free to pivot in the space between the knob  42  and the upper portion  25  of the link  24 . 
     FIGS. 10 and 11 depict another embodiment of the present invention, wherein a pair of holes  80 ,  82  bored in the handle  23  adjacent to the forward end thereof, near the link  24 . The handle  23  is also adapted to carry an attachment plate  84  for attaching a cord or lanyard  86  to the handle  23 . The free end of the lanyard  86  carries a pin  90  for being selectively and removably received in one of the holes  80 ,  82 . Preferably, the pin  90  is a “quick release,” pin of the commercially available type which include a ball or other suitable detent feature. When the pin  90  is lodged in hole  80 , as depicted in FIG. 10, the clamp  10  is in its unlocked mode, and when the pin  90  is placed in the other hole  82 , the clamp  10  is in its locked mode. 
     The materials for forming the clamp and latching mechanism of the present invention may be as follows: 
     
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                 Part 
                 Material 
               
               
                   
                   
               
             
             
               
                   
                 Latch bar 
                 6061 T6 aluminum 
               
               
                   
                 Latch bar pin 
                 18-8 stainless steel 
               
               
                   
                 Latch bar spring 
                 Type 302 stainless steel 
               
               
                   
                 Latch bar spring pin 
                 18-8 stainless steel 
               
               
                   
                 Latch pin 
                 18-8 stainless steel 
               
               
                   
                 Knob 
                 6061 T6 aluminum 
               
               
                   
                 Knob spring pin 
                 stainless steel with Delrin nose 
               
               
                   
                   
               
             
          
         
       
     
     Note that, as shown in FIGS. 2 and 4 (in phantom in FIG.  4 ), the clamping tool  10  may be provided in an embodiment with extended length handles for using the tool  10  on hard to reach work pieces, e.g., conduits or the like at the bottom of a trench. The handles of long-handled embodiments of the present invention may be of any selected length, as long the operating efficiency of the clamp/latch mechanism is not impaired. The latch bar  28  and knob  42  are machined or formed from stock purchased from ALCOA. The various springs and pins may be selected from commercially available items, included those available from McMaster-Carr and the knob spring pin is purchased from the Reid Tool Company. 
     The present invention may be embodied in other specific forms without departing from the essential spirit or attributes thereof. It is desired that the described embodiment be considered in all respects as illustrative, not restrictive.