Patent Publication Number: US-2005139043-A1

Title: Tool for detaching a piston from the disk brake base of a motor vehicle

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      This invention relates to a tool for detaching a piston from the disk brake base of a motor vehicle, particularly to one provided with an adjusting button turned to have its lower threaded rod pushing against the edge of one clamping member to move one grasping portion close to the other grasping portion and make two clamping portions expanded outward reversely. Subsequently, the two holding blocks of the two clamping members are inserted in the piston of a disk brake base and the two grasping portions are held and pressed inward. Then, turn around the adjusting button to expand outward the two clamping portions of the clamping members, and make the outer walls of the two holding blocks firmly press the inner wall of the piston and remove the piston out of the chamber of the disk brake base, convenient to replace a piston or a washer with a new one.  
      2. Description of the Prior Art  
      The disk brake base  1  of a motor vehicle, as shown in  FIG. 1 , includes a base body  10  provided with at least a chamber  11  having its inner wall formed with annular grooves  12  for fitting washers  13  therein and having a piston  14  fitted in the interior. In case the piston  14  or the washer  13  has been used for a long time and causes wear, needed to be replaced with a new one, it is detached from the base body  10  by a piston-detaching tool  2 . A conventional piston-detaching tool  2 , as shown in  FIG. 2 , includes two symmetrical clamping members  20 ,  21  pivotally combined together by a pivot  22 . The two clamping members  20 ,  21  have their front ends respectively formed with a clamping portion  200 ,  210 , and their rear ends respectively provided with a grasping portion  201 ,  211 , having a torsion spring  23  provided between the two grasping portions  201 ,  211 . The torsion spring  23  has two ends respectively hooked on the two grasping portions  201 ,  211  to expand them outward oppositely and make the two clamping portions  200 ,  210  closed together. Two holding blocks  202 ,  212  having pressed grains  203 ,  213  formed thereon are respectively secured to the front ends of the two clamping portions  200 ,  210  by bolts. In using, just hold the two grasping portions  201 ,  211  and insert the two holding blocks  202 ,  212  of the two clamping members  20 ,  21  into the piston  14  of the disk brake base  1  and then press inward the two grasping portions  201 ,  211  to expand outward the two clamping members  20 ,  21  to force the outer walls with the pressed grains  203 ,  213  of the two holding blocks  202 ,  212  firmly pressed on the inner wall of the piston  14 , and the piston  14  can be detached from the chamber  11  of the base body  10 .  
      However, the two grasping portions  201 ,  211  of the conventional piston-detaching tool  2  are always expanded outward oppositely by the torsion spring  23  so the distance between the two grasping portions  201 ,  211  is unable to be adjusted. Consequently, it is no easy work to tightly hold and press the two grasping portions  201 ,  211  with one hand to make the two holding blocks  202 ,  212  firmly pressed on the inner wall of the piston  14  and detach it from the base body  10 .  
     SUMMARY OF THE INVENTION  
      The objective of the invention is to offer a tool for detaching a piston from the disk brake base of a motor vehicle, which is able to adjust the distance between two grasping portions to facilitate grasping of the two grasping portions to let two clamping portions firmly pressed on the inner wall of the piston to remove it out of the disk brake base of a motor vehicle.  
      The feature of the invention is an adjusting base assembled near the intermediate portion of two clamping portions and having an adjusting button fitted thereon. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
      This invention will be better understood by referring to the accompanying drawings, wherein:  
       FIG. 1  is a perspective view of a conventional disk brake base of a motor vehicle;  
       FIG. 2  is a perspective view a conventional piston-detaching tool;  
       FIG. 3  is an exploded perspective view of a tool for detaching a piston from the disk brake base of a motor vehicle in the present invention;  
       FIG. 4  is a perspective view of the tool for detaching a piston from the disk brake base of a motor vehicle in the present invention; and,  
       FIG. 5  is a perspective view of the tool for detaching a piston from the disk brake base of a motor vehicle in a used condition in the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
      A preferred embodiment of a tool for detaching a piston from the disk brake base of a motor vehicle in the present invention, as shown in  FIG. 3 , includes two opposite clamping members  3 ,  4 , a torsion spring  6 , an adjusting base  7  and an adjusting button  8  as main components combined together.  
      The two clamping members  3 ,  4  pivotally combined together by a pivot  5  have their front ends respectively formed with a clamping portion  30 ,  40  and their rear ends respectively provided with a grasping portion  31 ,  41 .  
      The torsion spring  6  is fitted around a part of the pivot  5 , having one end hooked on the grasping portion  31  of the clamping member  3  and the other end hooked on the clamping portion  40  of the clamping member  4  to make the two grasping portions  31 ,  41  expanded outward oppositely and the two clamping portions  30 ,  40  closed together. The two clamping portions  30 ,  40  respectively have the front end provided with a holding block  32 ,  42  having pressed grains  33 ,  43  on the surface, and the clamping member  4  is bored with an insert hole  44 .  
      The adjusting base  7  shaped an inverted U is pivotally assembled on the clamping member  4 , having one sidewall bored with an insert hole  70  and its bent portion bored with a threaded hole  71 . A pivot  72  formed with an annular groove  73  is inserted through the insert hole  70  of the adjusting base  7  and the insert hole  44  of the clamping member  4  and fixed in place by a snap ring  74  clasped in the annular groove  73 .  
      The adjusting button  8  is threadably assembled on the threaded hole  71  of the adjusting base  7 , having its shank formed with a threaded rod  80 .  
      In assembling, as shown in  FIGS. 3 and 4 , firstly, the adjusting base  7  is mounted astride on the two clamping members  3 ,  4 , letting the insert hole  70  in one side wall of the adjusting base  7  aligned to the insert hole  44  of the clamping portion  4 , Next, the pivot  72  is inserted through the insert holes  70 ,  44  and fixed in position by the snap ring  74  clasped in the annular groove  73  to pivotally fix the adjusting base  7  on the clamping member  4 . Lastly, the threaded rod  80  of the adjusting button  8  is screwed in the threaded hole  71  of the adjusting base  7  to finish assembly of the piston-detaching tool.  
      In case the piston  14  or the washer  13  of a disk brake base  1  of a motor vehicle has been used for a long time and causes wear, necessary to be replaced with a new one by means of the piston detaching tool of the invention, as shown in  FIG. 5 , the adjusting button  8  is turned around to let the lower end of its threaded rod  80  push against the edge of the clamping member  3  and move the grasping portion  31  close to the grasping portion  41 . After the adjusting button  8  is turned to press the grasping portion  31  and the two holding blocks  32 ,  42  of the two clamping portions  30 ,  40  are expanded outward to a distance approximating to that of the inner diameter of the piston  14 , the two holding blocks  32 ,  42  of the two clamping members  3 ,  4  are inserted in the piston  14  of a disk brake base  1  and the two grasping portions  31 ,  41  are held and pressed inward to expand outward the two clamping members  3 ,  4  once more. Then, the adjusting button  8  is turned tight to make the two clamping portions  30 ,  40  expanded outward and fixed in position and the outer walls of the two holding blocks  32 ,  42  pressed firmly on the inner wall of the piston  14 . Thus, the piston  14  can easily be detached from the chamber  11  of the base body  10 , convenient to replace the piston  14  or the washer  13  with a new one.  
      While the preferred embodiment of the invention has been described above, it will be recognized and understood that various modifications may be made therein and the appended claims are intended to cover all such modifications that may fall within the spirit and scope of the invention.