Patent Publication Number: US-2015075335-A1

Title: Locking pliers with extendable jaws

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to locking pliers and more particularly to a pair of locking pliers having two arms at one ends of two handles respectively, the arms being adapted to extend to draw two jaws away from each other or retract to draw the jaws toward each other. 
     2. Description of Related Art 
     A conventional locking pliers  1  is shown in  FIG. 14  and comprises two handles  2  pivotably secured by a pivot  3 , a link and quick release assembly  8  having both ends pivotably secured to the handles  2  respectively; a hole  4  in a distal portion of each handle  2 , two arms  7  each having one end moveably disposed in the hole  4 , two jaws  5  each having one end secured to the other end of the arm  7  and the other end adapted to clamp an object by cooperating with the other jaw  5 , and two clamping members  6  each disposed on an inner surface of the hole  4  for frictionally fastening the arm  7 . 
     However, the conventional pair of locking pliers is not reliable in operation due to structural deficiencies. Further, it tends to malfunction. Thus, the need for improvement still exists. 
     SUMMARY OF THE INVENTION 
     It is therefore one object of the invention to provide a locking pliers comprising a first plier arm including a first handle and a first casing member having a first channel; a second plier arm including a second handle and a second casing member having a second channel; a pivot joint for pivotably joining the first and second handles; a first jaw carrier including a jaw at an open end, and a first arm member slidably disposed through the first channel and having a first end secured to the first jaw carrier, the first arm member including external teeth on a top surface and a bottom surface respectively, and a projection at a second end; a second jaw carrier including a jaw at an open end, and a second arm member slidably disposed through the second channel and having a first end secured to the second jaw carrier, the second arm member including external teeth on a top surface and a bottom surface respectively, and a projection at a second end; a biasing member put on the pivot joint and including a first arm element having a hook end fictionally put on the teeth on the top surface of the first arm member, and a second arm element having a hook end frictionally put on the teeth on the top surface of the second arm member; a first roller including teeth formed on an outer surface, the first roller being rotatably disposed on a bottom of the first channel and the teeth of the first roller being in rotatable tooth engagement with the teeth on the bottom surface of the first arm member; and a second roller including teeth formed on an outer surface, the second roller being rotatably disposed on a bottom of the second channel and the teeth of the second roller being in rotatable tooth engagement with the teeth on the bottom surface of the second arm member; wherein the first arm member is configured to pull out of the first channel a first predetermined distance; wherein the second arm member is configured to pull out of the second channel a second predetermined distance; wherein the teeth on the bottom surface of the first arm member are lockingly engaged with the teeth of the first roller when a first force is exerted on an exposed portion of the first arm member; and wherein the teeth on the bottom surface of the second arm member are lockingly engaged with the teeth of the second roller when a second force is exerted on an exposed portion of the second arm member. 
     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 perspective view of a pair of locking pliers according to a first preferred embodiment of the invention; 
         FIG. 2  is a side elevation is part section of the locking pliers; 
         FIG. 3  is a view similar to  FIG. 2  showing the jaws being disengaged in a ready to clamp position; 
         FIG. 4  is a sectional view taken along line  4 - 4  of  FIG. 3 ; 
         FIG. 5  is a fragmentary in part section view of the jaw assembly, the arm, and components adjacent the arm showing the arm being fully extended; 
         FIG. 6  is an enlarged view of the right side portion of  FIG. 5  showing teeth engagement of the arm with toothed surface of the roller when the arm is not free to extend or retract in response to force exerting thereon; 
         FIG. 7  is a perspective view of the roller; 
         FIG. 8  is an enlarged view of the left top portion of  FIG. 6  showing teeth engagement of the arm with toothed surface of the roller when the arm is free to extend or retract in response to no force exerting thereon; 
         FIG. 9  is a view similar to  FIG. 8  showing teeth engagement of the arm with toothed surface of the roller when the arm is not free to extend or retract in response to force exerting thereon; 
         FIG. 9A  is a view similar to  FIG. 9  showing another configuration of the roller where the roller is disposed at an opposite side; 
         FIG. 10  is a perspective view of a pair of locking pliers according to a second preferred embodiment of the invention; 
         FIG. 11  is a fragmentary in part section of the locking pliers of  FIG. 10  showing the arm and adjacent components; 
         FIG. 12  is an enlarged view of the left top portion of  FIG. 11  showing teeth engagement of the arm with toothed surface of each roller when the arm is not free to extend or retract in response to force exerting thereon; 
         FIG. 13  is a view similar to  FIG. 12  showing another configuration of the roller where the roller has top teeth a which are in tooth engagement with the bottom teeth of the arm; and 
         FIG. 14  is a side elevation in part section of a conventional pair of locking pliers, the lock pliers being open with a piece being clamped by the jaws. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1 to 9 , a pair of locking pliers  10  in accordance with a first preferred embodiment of the invention comprises the following components as discussed in detail below. 
     Two bent plier arms  11  each include a handle  12  and an inclined casing member  13 . The housings  13  are pivotably joined at a pivot joint  14 . A link and quick release assembly  30  has both ends pivotably secured to the handles  12  respectively. A channel  131  is formed through the casing member  13 . Two jaw carriers  21  each comprises a pivotal jaw  20  at an open end, and an arm  22  slidably disposed through the channel  131  and having one end secured to the jaw carrier  21 . The arm  22  includes external teeth b on a top surface  222  and a bottom surface  221  respectively, and a projection  223  at the other end. The projection  223  is used to prevent the arm  22  from being inadvertently pulled out of the channel  13 . A torsion spring  50  is put on the pivot joint  14  and includes a first arm  51  having a hook end  511  fictionally put on the teeth b on the top surface  222  of one arm  22 , and a second arm  52  having a hook end  521  frictionally put on the teeth b on the top surface  222  of the other arm  22 . Two rollers  40  each include an outer surface  401  formed with teeth a. The roller  40  is rotatably provided on a bottom of the channel  131  at an open end of the casing member  13  facing the jaw carrier  21 . The teeth a of the roller  40  are in rotatable tooth engagement with the teeth b on the bottom surface  221  of the arm  22 . 
     In use including distance adjustment, a user may pull the arm(s)  22  a desired distance so that a distance such as W or 3W can be obtained. Further, a piece (not shown) can be clamped by the jaws  20 . The characteristics of the invention are that the pulling of the arm  22  is not obstructed (see  FIGS. 5 and 8 ). But the teeth b on the bottom surface  221  of the arm  22  are lockingly engaged with the teeth a of the roller  40  when a force is exerted on an exposed portion of the arm  22  (see  FIGS. 6 and 9 ). This is the case when the piece is clamped by the jaws  20 . Thus, the clamped piece is secured without being loosened. 
     Referring to  FIG. 9A , in another configuration each of the rollers  40  are rotatably provided between an inner end of the channel  131  and the hook end  511  of the torsion spring  50  and the teeth a of the roller  40  are in rotatable tooth engagement with the teeth b on the top surface  222  of the arm  22 . 
     Referring to  FIGS. 10 and 12 , a pair of locking pliers  10  in accordance with a second preferred embodiment of the invention is shown. The characteristics of the second preferred embodiment are substantially the same as that of the first preferred embodiment except the following: 
     The roller is replaced with a first roller  41  and a second roller  42 . The first roller  41  is rotatably provided on a bottom of the channel  131  at an open end of the casing member  13  facing the jaw carrier  21 . The teeth a of the first roller  40  are in rotatable tooth engagement with the teeth b on the bottom surface  221  of the arm  22 . The second roller  42  is rotatably provided between an inner end of the channel  131  and the hook end  511  of the torsion spring  50  and the teeth a of the roller  40  are in rotatable tooth engagement with the teeth b on the top surface  222  of the arm  22 . 
     Referring to  FIG. 13 , in another configuration a plate member  43  is rotatably provided on a bottom of the channel  131  at an open end of the casing member  13 . Top teeth a of the plate  43  are in rotatable tooth engagement with the teeth b on the bottom surface  221  of the arm  22 . 
     While the invention has been described in terms of preferred embodiments, those skilled in the art will recognize that the invention can be practiced with modifications within the spirit and scope of the appended claims.