Patent Publication Number: US-7222558-B2

Title: Gripping pliers

Description:
BACKGROUND OF THE INVENTION 
   The invention relates to a pair of gripping pliers, generally called “water pump pliers”. A pair of water pump pliers is generally understood to be a pair of pliers with a first and a second leg (“clamp” and “handle”), each of which have a handle portion and a pliers yaw and which are interconnected between the handle portions and the pliers yaws by means of a joint. The joint is guided in a longitudinal aperture of the first leg, this aperture being provided with detents. By adjusting the joint in the longitudinal aperture, the opening width of the pliers, i.e. the spacing of the pliers yaws, can be varied with substantially parallel gripping surfaces. By such an arrangement, it is possible to adapt the opening width to the dimensions of the part to be gripped and to grasp parts of considerably different diameters in the same way. A flat section with a longitudinal slot is provided at the clamp, the handle extending through this longitudinal slot. Parallel cheeks are formed on both sides of this longitudinal slot. 
   DESCRIPTION OF THE PRIOR ART 
   Gripping pliers of this type are known, wherein the joint, in a first axial position thereof, can be shifted in the longitudinal aperture and, in a second axial position thereof, can be locked in one of a series of detent positions. (company catalogue of KNIPEX.page 73: “KNIPEX-Cobra, EP 0 116 305 A1, EP 0 528 252 A1, EP 0 774 324 A2). With these prior Art gripping pliers, a single longitudinal aperture is provided in the central pliers clamp. The cheeks of the handle have bearing bores of different diameters. The detent positions are defined by two toothed edges having generally triangular teeth. The joint has a detent body, which has a cylindrical bearing surface of relatively large diameter, a section with opposite toothing structures adapted to engage the toothed edges, and a cylindrical bearing surface of relatively small diameter. The small diameter bearing surface extends, as a push button, out of the handle. In a first axial position of the detent body, the push button is depressed. In this position, the large diameter bearing surface is pushed out of the handle. The section with the toothing structures is located in a bore of the handle having the relatively large diameter. The bearing surface having the smaller diameter is located between the teeth of the two toothed edges. Thereby, the handle can be adjusted relative to the clamp along the longitudinal apertures. In the second axial position, the toothed section engages the toothed edges. Thereby, the joint is locked. The large diameter bearing surface is rotatable in the corresponding bore. The small diameter section is rotatable in the bore of small diameter. Now the handle can be rotated in the new detent position with the two cylindrical bearing surfaces relative to the clamp. 
   EP 0 904 898 B1 describes a pair of gripping pliers, wherein two aligned longitudinal apertures are provided in the cheeks. Each of the longitudinal apertures is formed by overlapping bores. Each of the bores defines a detent position for a joint. A first longitudinal aperture is formed by bores of relatively small diameters, while the second longitudinal bore is formed by bores of relatively large diameters. A bore in the handle has also the relatively large diameter. The joint is formed by a twice stepped, axially displaceable pivot, which has a push button of smaller diameter extending out of the clamp. In a first axial position, the push button of smaller diameter is located in the first longitudinal aperture, and the opposite section with the relatively large diameter is pushed out of the bore of the second longitudinal aperture. In this axial position, the joint with the handle can be shifted in the clamp along the longitudinal apertures. In a second axial position, the median section of the stepped pivot rotates in one of the bores forming the first longitudinal aperture, while the end section of the stepped pivot is rotatable in a bore which forms part of the second longitudinal aperture. 
   With this prior art pair of gripping pliers, the detent positions are defined by the overlapping bores of the longitudinal apertures. These bores, at the same time, are the bearing surfaces for the pivot forming the joint. With this pair of gripping pliers, the distance of the detent positions is defined by the dimensions of the bores. These bores, however, have to have a certain size, whereby the possible minimum spacing of the detent positions is limited. 
   SUMMARY OF THE INVENTION 
   It is an object of the invention to improve the bearing structure of the joint in pairs of gripping pliers of this type. It is another object of the invention, to permit fine adjustment of the opening width of the pair of gripping pliers. 
   To this end a pair of gripping pliers is provided comprising a pliers clamp and a pliers handle, said pliers clamp having a handle portion at one end and a pliers yaw at the opposite end, and said pliers handle having a handle portion at one end and a pliers yaw at the opposite end. Said clamp has a longitudinal slot between said handle portion and said pliers yaw thereof, said longitudinal slot defining a pair of parallel inner surfaces. Said pliers handle extends through said longitudinal slot. Said clamp has aligned longitudinal apertures on both sides of said longitudinal slot, said longitudinal apertures defining detent positions. The pair of gripping pliers further comprises joint means for articulated interconnection of said clamp and said handle. Said joint means include a detent body movable between a first axial position and a second axial position, said detent body, in its first axial position, permitting movement of said joint means in said longitudinal slot and, in its second axial position, is adapted to lock in anyone of said detent positions. 
   Said detent positions are defined by toothed edges along at least one of said aligned longitudinal apertures. Said detent body has at least two axially spaced detent lugs for engagement with said toothed edges. Said joint means comprise a bearing ring with end faces, said bearing ring surrounding said detent body and having axial dimensions substantially equal to those of said handle, said bearing ring being guided with its end faces between said inner surfaces of said slot. Said pliers handle is rotatably mounted on said bearing ring, and said bearing ring is a profiled ring having a central aperture and radial recesses extending from said central aperture, said radial recesses being substantially complementary to said detent lugs, a pair of said detent lugs of said detent body engaging said radial recesses in said second detent position of said detent body. 
   In this way, the joint, on one hand, is ruggedly supported in detent positions provided on both sides of the central second leg. On the other hand, a fine adjustment in accordance with the tooth spacing of the toothed edges is possible. Preferably said toothed edges comprise teeth and tooth gaps of substantially triangular shape, and said detent lugs are substantially roof-shaped projections of said detent body. This permits very fine adjustment of the opening width of the gripping pliers. 
   It is advantageous, if detent lugs of said detent body partly engage said radial recesses of said profiled bearing ring also in said second axial position of said detent body. Thereby, the relative orientation of the profiled bearing ring with respect to the detent lugs is ensured, such that movement of the detent body from its first axial position to its second axial position is always possible. 
   The pair of pliers may further comprise resilient means for biasing said detent body towards said second axial position, said resilient means being supported by said profiled bearing ring. In order to reduce friction, when shifting the joint, said profiled bearing ring may have a stepped peripheral surface and may be mounted in a correspondingly stepped bore of said handle such as to maintaining an end face of said profiled bearing ring remote from said resilient means spaced from the neighboring one of said inner surfaces of said longitudinal slot. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a view of a pair of gripping pliers as viewed from one side. 
       FIG. 2  shows the pair of gripping pliers as viewed from the opposite side. 
       FIG. 3  is a sectional view taken along line III—III of  FIG. 2  of a first embodiment of the pair of gripping pliers. 
       FIG. 3A  is a sectional view taken along line III—III of  FIG. 2  of a modified embodiment of the pair of gripping pliers. 
       FIG. 4  is a detail view and shows an insert with elongated aperture and detents in the pair of gripping pliers of  FIGS. 1 and 2 . 
       FIG. 5  is an enlarged illustration as viewed in the direction of the joint axis of the gripping pliers and shows the elongated aperture provided with detents, a profiled bearing ring for the mounting of the handle and a detent body. 
       FIG. 6  is a front view of the profiled bearing body in the embodiment of  FIG. 3 . 
       FIG. 7  is a side view of this profiled bearing body. 
       FIG. 6A  is a front view of the profiled bearing body in the embodiment of  FIG. 3A . 
       FIG. 7A  is a side view of the profiled bearing body of  FIG. 6A . 
       FIG. 8  is a side elevation of the major portion of the detent body. 
       FIG. 9  is a side elevation of the major portion of the detent body as viewed from the right in  FIG. 8 . 
       FIG. 10  is a view of the major portion of the detent body from below in  FIG. 8 . 
       FIG. 11  is a side elevation of the push-down plate of the detent body. 
   

   DESCRIPTION OF THE EMBODIMENT 
     FIGS. 1 and 2  show a pair of gripping pliers viewed from opposite sides. In the art, such a pair of gripping pliers is termed “water pump pliers”. The gripping pliers has a first leg or “clamp”  10  and a second leg or “handle”  12 . Clamp and handle are articulated by means of a joint  14 . The clamp  10  has a handle portion  16  and a pliers yaw  18 . The handle  12  has a handle portion  20  and a pliers yaw  22 . The pliers yaws  18  and  22  are angled relative to the handle portions  16  and  20 , respectively, such that their gripping surfaces  24  and  26 , respectively, facing each other are substantially parallel, when the pair of gripping pliers is in its closing or gripping position. Each of the gripping surfaces forms a recess toothed in conventional manner to permit holding of a tube or the like between the gripping surfaces. 
   In the region of the joint  14 , the clamp  10  has a slot  28  ( FIG. 3  or  3 A) extending through the clamp  10 , the plane of this slot extending normal to the axis of rotation  30  of the joint  14 . Clamp halves or cheeks  32  and  34  are formed on both sides of the slot  28 . These clamp halves or cheeks  34  and  34  are plate-like broadened relative to the end portion of the handle portion  16 . Elongated apertures are  36  and  38  are provided in these clamp halves  32  and  34 , respectively. Plates  40  and  42  are retained in these apertures  36  and  38 , respectively. Longitudinal apertures  44  and  46  are formed in these plates  40  and  42 , respectively. The longitudinal apertures  44  and  46  are aligned. Detent positions are provided along the longitudinal apertures  44  and  46 . The detent positions are defined by pairs of toothed edges  48 ,  50  and  52 ,  54  facing each other ( FIGS. 4 and 5 . The toothed edges consist of teeth and tooth gaps of substantially triangular shape. 
   The handle  12  extends through the slot  28 . The joint interconnects clamp  10  and handle  12 . The joint can be locked in the various detent positions defined by the toothed edges  48 ,  50  and  52 ,  54 . In a stop position, the inclined outer surface of the plate-like section  56  of the clamp  10  engages a stop  58  of the handle  12  ( FIG. 2 ). In this stop position, the gripping surfaces  24  and  26  of the two plier yaws  18  and  22 , respectively, are substantially mutually parallel. The opening width, i.e. the spacing of the plier yaws in this parallel position is varied depending on the detent position in which the joint  14  is locked. In this way, the opening width can be adapted to the dimensions of the objects to be handled. Objects of widely different dimensions can be grasped by the pair of gripping pliers in substantially the same way. 
   The construction of the lockable joint  14  can best be seen from  FIG. 3 . The joint  14  has a spring-loaded push-button  60 . By depressing this push-button, the joint is released from its detent position and can be shifted in the longitudinal apertures  44  and  46  into another detent position. The push-button forms part of a detent body  62 . The detent body has a shaft  64  provided centrally at the detent body  60 . The shaft extends through the longitudinal apertures  44  and  46  of the clamp  10 . Two pairs of diametrically opposite detent lugs  66 ,  68  and  70 ,  72  are integral with the shaft  64 . The pairs of detent lugs  66 ,  68  and  70 ,  72  axially spaced such that, in the operative position illustrated on the right side in  FIG. 3 , the detent lugs  66  and  68  engage the toothed edges  48  and  50 , respectively, and the detent lugs  70  and  72  engage the toothed edges  52  and  54 , respectively. In the right portion of  FIG. 4 , the joint  14  is shown locked and in its operative position. In the left portion of  FIG. 3 , the joint  14  is illustrated such that, after depressing the push-button, it can be shifted along the longitudinal apertures  44  and  46  to a new detent position. In the lower end face of the shaft  64 , as viewed in  FIG. 3 , a blind bore  74  is provided. A knurled shaft  76  of a push-down plate  78  is pressed into this blind bore  74 . 
     FIGS. 8 to 10  are single-part drawings of the detent body  62 . The detent body  62  has the push-button  60 . A diametrically extending block  80  is attached to the push-button  60 . When the detent body is assembled, the block  80  extends in the direction of the longitudinal apertures  44  and  46 . The block  80  has axial blind bores  82  and  84  on both sides of the shaft  64 . The blind bores  82  and  84  accommodate the ends of helical springs (not shown) which urge the detent body  62  into the operative position shown on the right side of  FIG. 3 . The pairs of detent lugs  66 ,  68  and  70 ,  72  are integral with the shaft  64 . The roof-like shape of the detent lugs can be seen from  FIG. 10 . The blind bore  74  is illustrated in the end face of the shaft remote from the push-button. 
   A profiled bearing ring  86  is mounted on the detent body  62 . In the embodiment of  FIGS. 3   6  and  7 , this profiled bearing ring  86  has a cylindrical peripheral surface. With this peripheral surface, the profiled bearing ring  86  is mounted in a corresponding aperture  88  of the handle  12  of the pair of gripping pliers. The thickness of the profiled bearing ring  86  is equal to the thickness of the handle  12  in the region of the longitudinal apertures  44  and  46 . The end faces of the profiled bearing ring  86  are guided between the inner surfaces of the slot  28  outwards of the toothed edges  48 ,  50  and  52 ,  54 . The profiled bearing ring  86  has a central aperture  90 . This central aperture can be seen best from the single-part drawing of  FIG. 6 . The aperture  90  has a circular central portion  92  which communicates with substantially triangular, diametrically opposite recesses  94  and  96 . The cross sections of the recesses  94 ,  96  are limited by tangents engaging the circular central portion and forming an angle of 90°. With these recesses, the profiled bearing ring is guided on the detent lugs  66  and  68  of the detent body  62 . As can be seen from  FIG. 3 , the detent lugs  66  and  68  engage, in the operative position (on the right side of  FIG. 3 ), the detent lugs  66  and  68  engage, with their edge portions only, edge portions of the recesses  94  and  96 , so that the mutual alignment of detent body and profiled bearing ring is ensured. After the push-button  60  has been depressed (left side of  FIG. 3 ) the detent lugs  66  and  68  engage the recesses  66  and  68  on their whole length symmetrically to the transverse center plane of the profiled bearing ring  68 . If then the joint  14  is shifted along the longitudinal apertures  44  and  46 , the profiled bearing ring  86  is coupled symmetrically with the detent body  62 , whereby no tilting torques occur. 
   As can be seen from the left portion of  FIG. 3 , the joint  14  is de-coupled from the outer leg, after the push-button  60  has been depressed. The detent lugs  66  and  68  are out of engagement with the toothed edges  48  and  50 , respectively. The detent lugs  70  and  72  are out of engagement with the toothed edges  52  and  54 , respectively. The detent lugs  66  and  68  engage the recesses  94  and  96 , respectively, of the profiled bearing body  86 . The detent lugs  70  and  72  are located outside the cheek  34 . In this state, the handle  14  with the joint  14 , the detent body  62  and the profiled bearing ring  86  can be shifted along the longitudinal apertures  44  and  46 . Thereby, the opening width of the gripping pliers can be adapted to the dimensions of the object to be grasped. In practice, this is done in the following way: The gripping pliers are widely opened. Then the pliers yaw  18  of the clamp is brought with its gripping surface  24  into engagement with the object to be grasped. The push-button  60  is pressed down, and the joint  14  together with the handle  12  is shifted in the longitudinal apertures relative to the clamp, until the gripping surface  26  of the pliers yaw  22  of the handle engages the object to be grasped. Then the push-button  60  is released. Hereby, the detent body  62  returns to its operative position (right portion of  FIG. 3 ). The detent lugs  66  and  68  engage the toothed edges  48  and  50 , respectively, and the detent lugs  70  and  72  engage the toothed edges  52  and  54 , respectively. Because of the finely graduated gear profile of the toothed edges, fine adjustment of the joint  14  is possible. The joint  14  is supported in the two cheeks  32  and  34  of the clamp  10  on both sides of the handle. This results in a rugged design. 
   The helical springs (not shown) which are retained with one end in the bores  82  and  84  of the detent body  62  are supported on the profiled bearing ring  86 . They extend through the longitudinal aperture  44 . Because of this support, a reaction force is generated which urges the profiled bearing ring  86  towards the inner surface of the clamp half or cheek  34 . Thereby, friction is caused, which counter-acts any shift of the joint. The profiled bearing ring  86  is part of the joint  14  and is shifted relative to the clamp half, when the joint is shifted. This friction is avoided with an arrangement as shown in  FIG. 3A  and  FIGS. 6A and 7A . The joint  14  is of similar construction as that of  FIG. 3  and  FIGS. 6 and 7 , and corresponding elements bear the same reference numerals. 
   As can be seen from  FIGS. 6 and 7 , the peripheral surface of the profiled bearing ring  86 A is stepped. The peripheral surface comprises a cylindrical section  100  of relatively large diameter and a cylindrical section  102  of relatively small diameter. The diameter of the section  102  is about equal to the outer diameter of the profiled bearing ring  86  of  FIGS. 3 ,  6  and  7 . A step or annular shoulder  104  is formed between the sections  100  and  102 . The aperture  88 A of the handle  12 , corresponding to aperture  88  of  FIG. 3  has an inner surface stepped complementarily to the profiled bearing ring, and widens stepwise towards the top of  FIG. 3A . 
   With such an arrangement, the reaction force of the helical springs, which acts between block  80  and profiled bearing ring  86 A, will not be taken up by the clamp  10  but by the median handle  12  of the pair of gripping pliers. Then the profiled bearing ring rests with the step or annular shoulder  104  on the corresponding annular shoulder of the stepped aperture  88 A. Thus the profiled bearing ring is supported on the handle. When the joint  14  is shifted, the handle  12  is moved together with the joint  14  in the longitudinal apertures  44  and  46 . Thereby, no relative movement between these parts occurs and, consequently, also no frictional resistance due to the helical springs.