Patent Publication Number: US-6655670-B1

Title: Transmission mechanism for clamping device

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a transmission mechanism for clamping device, and more particularly to a transmission mechanism for clamping device having two sets of front and rear push members with one elastic plastic-steel cushion disposed between the front and the rear push member, so that the push members do not easily loosen from a scaled rod of the clamping device due to an overly large force applied on the push members via an operating handle. 
     FIG. 1 shows a conventional clamping device generally available in the markets. The conventional clamping device includes a transmission mechanism in which an operating handle A is pivotally turned to incline a push member E behind the operating handle A. When the push member E is inclined, an opening B thereof engaging with a scaled rod D of the clamping device also inclines to firmly contact with, press against, and push the scaled rod D, which is fixedly connected to a movable jaw C of the clamping device, so that the scaled rod D, and accordingly the movable jaw C, are shifted. 
     A disadvantage of the above-described transmission mechanism for the conventional clamping device is that there is only one single push member E provided behind the operating handle A, and that the push member E tends to become loosened from the scaled rod D at the opening B when an overly large force is applied on the push member E via the operating handle A. The conventional clamping device also requires an operator to hold and operate the device laboriously to cause a sore and tired hand easily. 
     SUMMARY OF THE INVENTION 
     A primary object of the present invention is to provide an improved transmission mechanism for a clamping device that can be easily operated without the risk of having push members loosened from the scalded rod due to an overly large force applied via the operating handle. 
     Another object of the present invention is to provide an improved transmission mechanism for a clamping device that enables an operator to handle the clamping device in an easy and laborsaving manner. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein 
     FIG. 1 is a partially sectioned side view of a conventional clamping device showing a transmission mechanism thereof; 
     FIG. 2 is a partially sectioned side view of a clamping device according to the present invention showing a transmission mechanism thereof; and 
     FIGS. 3 and 4 are fragmentary, enlarged, and partially sectioned side views of the clamping device of the present invention showing the operation thereof. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Please refer to FIG. 2 that is a partially sectioned side view of a clamping device showing a transmission mechanism according to the present invention. As shown, the clamping device and the transmission mechanism thereof includes two operating handles  1  and  2 , a movable jaw  12 , a scaled rod  13  extended through and connected to the movable jaw  12 , and two sets of front and rear push members  3 ,  4  and  5 ,  6  mounted on the scaled rod  13  to locate behind the operating handles  1  and  2 , respectively. Each set of the push members  3 ,  4  and  5 ,  6  has a plastic-steel cushion  7 ,  8  with a predetermined elasticity disposed therebetween. The pushing members  3 ,  4 ,  5 , and  6  are respectively pivotally connected to the clamping device at pivotal points  9 . The push members  3 ,  4  are provided with openings  31 ,  41  at where the push members  3 ,  4  are engaged with the scaled rod  13 . The two rear push members  4 ,  6  behind the two operating handles  1 ,  2 , respectively, are provided at respective outer side with a compression spring  10 ,  11  to enable the two sets of front and rear push members  3 ,  4  and  5 ,  6  to automatically return to their initial positions after they are pivotally turned. 
     Please now refer to FIGS. 3 and 4 that are fragmentary, enlarged, and partially sectioned side views of the clamping device showing operations thereof to shift the scaled rod  13  and accordingly the movable jaw  12 . When an operator holds and pulls the operating handle  1 , the operating handle  1  is pivotally turned to generate a force that is transmitted to the front push member  3 . The elastic plastic-steel cushion  7  buffers the force and then transmits the same from the front push member  3  to the rear push member  4 , so that the openings  31 ,  41  of the push members  3 ,  4  are in an inclined position relative to the scaled rod  13 . The openings  31 ,  41  in the inclined position cause the push members  3 ,  4  to tightly contact with, press against, and push the scaled rod  13  that is firmly screwed to the movable jaw  12 . When the scaled rod  13  is pushed by the inclined openings  31 ,  41  of the push members  3 ,  4  to shift, the movable jaw  12  connected thereto is moved accordingly. 
     Since the force transmitted from the operating handle  1  to the front push member  3  is buffered at the elastic plastic-steel cushion  7  before being further transmitted to and distributed over the rear push member  4 , the push members  3 ,  4  would not loosen from the scaled rod  13  at the openings  31 ,  41  due to an overly large force applied on the push members  3 ,  4  via the operating handle  1 . Meanwhile, the operator may operate the clamping device with less effort to avoid a sore and tired hand manipulating the clamping device.