Abstract:
A bar clamp has an operating handle being in ratchet engagement with end teeth of a slide bar. The operating handle is adapted to pivot counterclockwise to cause a first clamping jaw carrier to displace along the slide bar and then pivot about a lock pin in the slide bar so as to displace a first clamping jaw a sufficiently large distance to securely clamp a workpiece by cooperating with a corresponding clamping jaw.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of Invention 
   The invention relates to bar clamps and more particularly to a bar clamp having an arrangement for displacing a clamping jaw a large distance in order to securely clamp a workpiece by cooperating with a corresponding clamping jaw. 
   2. Description of Related Art 
   A conventional eccentric clamp disclosed in U.S. Pat. No. 6,648,314 is shown in  FIGS. 1 and 2 . The clamp operates as below. A workpiece is preliminarily clamped between a clamping jaw of a fixed but pivotable clamping jaw carrier  12  and a clamping jaw of a displaceable clamping jaw carrier  10 . Next, counterclockwise pivot an operating handle  11  about 180 degrees to cause the clamping jaw carrier  12  to pivot a predetermined small angle so as to longitudinally displace the clamping jaw of the clamping jaw carrier  12  a predetermined distance as indicated by Y. 
   However, the patented clamp suffers from a disadvantage. In detail, the displacement distance Y is relatively small. Hence, the clamping force exerted upon the workpiece is not sufficient. It is understood that a user has to latch and unlatch the operating handle  11  a number of times before the workpiece can be securely clamped. Thus, a need for improvement exists. 
   SUMMARY OF THE INVENTION 
   It is therefore one object of the invention to provide a bar clamp having an arrangement for displacing a clamping jaw a large distance in order to securely clamp a workpiece by cooperating with a corresponding clamping jaw. 
   The above and other objects, features and advantages of the invention will become apparent from the following detailed description taken with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side phantom view in part section of a conventional clamp; 
       FIG. 2  is a view similar to  FIG. 1  where a clamping operation by pivoting an operating handle is shown; 
       FIG. 3  is a side phantom view of a preferred embodiment of bar clamp according to the invention; 
       FIG. 4  is a side phantom view in part section of the bar clamp of  FIG. 3  where the bar clamp is in an inoperative position; and 
       FIGS. 5 and 6  are views similar to  FIG. 4  showing the operating handle being counterclockwise pivoted to advance and pivot the first clamping jaw carrier in a clamping operation. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIGS. 3 to 6 , a bar clamp in accordance with a preferred embodiment of the invention comprises the following components. Each component is discussed in detail below. 
   A slide bar  20  comprises an arcuate toothed section  21  on a front end, a substantially triangular channel  22  proximate the toothed section  21 , and a lengthwise elongated slot  23  behind the channel  22 . 
   A first clamping jaw carrier  40  comprises a compartment  42  with the slide bar  20  extending through, a pivot hole  44  aligned with the slot  23 , and a triangular hole  43  aligned with the channel  22 , the triangular hole  43  having a longitudinal surface  431  and a transverse surface  432  shown in phantom lines of  FIG. 5 . 
   An operating handle  30  is hollow and comprises a pivot hole  32  aligned with both the hole  43  and the channel  22 , a large arcuate pressure surface  31  at one end engaged with a first oblique surface  45  of the first clamping jaw carrier  40 , a small arcuate pressure surface  311  continuous with the large arcuate pressure surface  31  also at one end, the small arcuate pressure surface  311  engaged with a joining point of the first oblique surface  45  and a second oblique surface  451  of the first clamping jaw carrier  40 , a pivotal release level  34  provided in the hollow of the operating handle  30 , a compression spring  35  anchored between an end of the operating handle  30  and an end of the release level  34 , and an intermediate ratchet member  33  having one end retained in a cavity  341  at the other end of the release level  34  and the other end formed with ratchet teeth which are engaged with the toothed section  21 . 
   A pin  60  is provided across the channel  22 , the triangular hole  43 , and the pivot hole  32  in order to pivotably secure the operating handle  30 , the slide bar  20 , and the first clamping jaw carrier  40  together. 
   A lock pin  70  is provided across the slot  23  and the pivot hole  44  in order to slidably secure the first clamping jaw carrier  40  to the slide bar  20 . 
   An arcuate clamping section  46  is formed on an end of the first clamping jaw carrier  40  distal the slide bar  20 . The clamping section  46  has an end  461  and a first clamping jaw  462  pivotably secured to the end  461 . 
   A second clamping jaw carrier  50  is provided opposite the first clamping jaw carrier  40  and has a compartment (not numbered) with the slide bar  20  extending through so that the second clamping jaw carrier  50  is capable of displacing along the slide bar  20 . The second clamping jaw carrier  50  has a second clamping jaw  51  which is also pivotably secured to its end. The second clamping jaw  51  is opposite the first clamping jaw  462 . 
   A clamping operation of the invention will be described in detail below. In  FIG. 5 , a workpiece (not shown) is preliminarily clamped between the first clamping jaw  462  of the displaceable pivotable first clamping jaw carrier  40  and the second clamping jaw  51  of the displaceable second clamping jaw carrier  50  by moving the second clamping jaw carrier  50  toward the first clamping jaw carrier  40 . Next, counterclockwise pivot the operating handle  30  an acute angle as indicated by an arrow shown in a phantom line to move the ratchet member  33  along the toothed section  21 . Also, the large arcuate pressure surface  31  exerts a pressure on the first oblique surface  45  of the first clamping jaw carrier  40  and the small arcuate pressure surface  311  exerts a pressure on the second oblique surface  451  of the first clamping jaw carrier  40  respectively. Hence, the triangular hole  43  moves downward, i.e., the longitudinal surface  431  thereof moving downward by engaging with the pin  60 . Also, the first clamping jaw carrier  40  moves downward relative to the slide bar  20  by sliding the lock pin  70  downward relative to and along the slot  23 . 
   In  FIG. 6 , further counterclockwise pivot the operating handle  30  another acute angle as indicated by an arrow shown in a phantom line to move the ratchet member  33  along the toothed section  21 . Also, the large arcuate pressure surface  31  exerts a pressure on the first oblique surface  45  of the first clamping jaw carrier  40 . The longitudinal movement of the first clamping jaw carrier  40  will be stopped when the lock pin  70  engages with the bottom end of the slot  23 . After stopping, the first clamping jaw carrier  40  immediately pivots counterclockwise about the lock pin  70 . Also, the transverse surface  432  of the triangular hole  43  moves leftward relative to the pin  60  by engaging therewith. Hence, the first clamping jaw carrier  40  pivots counterclockwise to cause the first clamping jaw  462  to displace a large distance as indicated by X. As a result, the workpiece is securely clamped. It is understood that a pressing of the release level  34  can disengage the ratchet member  33  from the toothed section  21  and a next clockwise pivoting of the operating handle  30  can return the operating handle  30  to its original inoperative position. 
   While the invention herein disclosed has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of the invention set forth in the claims.