Self-adjusting pliers

Information

  • Patent Grant
  • 6212978
  • Patent Number
    6,212,978
  • Date Filed
    Tuesday, June 15, 1999
    25 years ago
  • Date Issued
    Tuesday, April 10, 2001
    23 years ago
Abstract
A self-adjusting pliers has an upper arm with an upper jaw at a first end and an upper handle at a second end. A support extends downwardly from an intermediate location of the upper arm. The support has a first downwardly extending slot and a second downwardly extending slot that is parallel to the first downwardly extending slot and closer to the upper handle than the first downwardly extending slot. The second downwardly extending slot has a plurality of second-slot teeth on a side thereof adjacent to the first downwardly extending slot. A lower arm includes a first end, and a lower handle at a second end. A control arm is pivotably connected at a first end to the upper handle and at a second end to the lower arm at an intermediate location between the first end and the lower handle. A spring is affixed at a first end to the upper arm at a location adjacent to the first end thereof, and affixed at a second end to the control arm so as to resist rotation of the control arm. A lower jaw member includes a lower jaw at a first end and in a facing relationship to the upper jaw. A slider extends from a side of the lower jaw member and is slidably engaged to the first downwardly extending slot. A pawl is disposed within the second downwardly extending slot and has a set of pawl teeth in facing relationship to the second slot teeth. A shifter has three pivot points arranged in a triangular pattern, the three pivot points being respectively connected to the lower jaw member, to the pawl, and to the first end of the lower arm.
Description




BACKGROUND OF THE INVENTION




This invention relates to pliers, and, more particularly, to a self-adjusting pliers that grips workpieces of various sizes without manual adjustment.




The traditional version of a pliers includes two elongated members joined at a pivot pin. One end of each elongated member forms a jaw, and the other forms a handle. Workpieces of different sizes are grasped in different manners, due to the constant geometry of the elongated members and the jaws. Some adjustability may be achieved by providing a slotted receiver in one of the handles, so that the handle with the pivot pin may be moved between different positions in the slot to provide adjustability for gripping objects of different sizes.




U.S. Pat. No. 4,651,598 provides an improved pliers whose jaws are self adjusting according to the size of the workpiece. Commercial versions of this pliers are useful, but have important drawbacks. Perhaps the most significant problem with the pliers made according to the '598 patent is that the jaws move relative to each other in an end-to-end manner as they are clamped down onto a workpiece. Soft workpieces such as brass or copper may be marred as a result. The clamping force applied by these pliers depends upon the size of the workpiece being grasped. Additionally, these pliers cannot be locked closed for convenient carrying and storage.




Another problem with the pliers of the '598 patent is that they do not lock to the workpiece, an important convenience in some uses of pliers. Overcenter locking pliers are described in a series of patents such as U.S. Pat. No. 4,541,312. Conventional overcenter locking pliers provide adjustability in the size of the workpiece that may be gripped through a screw adjustment to the pivoting position of the control arm, but this adjustability is not automatic in the sense of the pliers of the '598 patent.




Other types of locking pliers such as the AutoLock™ pliers combine the self-adjusting feature with an overcenter locking mechanism. This pliers can be inconvenient to use for some sizes of workpieces, suffers from some of the problems of the pliers of the '598 patent, does not achieve a large gripping force, and may unexpectedly unlock when large objects are being gripped.




There is a need for a self-adjusting pliers which does not experience shifting of the jaw position as the object is grasped, and which may be provided in a locking version. The present invention fulfills this need.




SUMMARY OF THE INVENTION




The present invention provides a self-adjusting pliers wherein the jaws automatically adjust to various sizes of workpieces. There is no end-to-end relative movement of the jaws as they grasp the workpiece, so that there can be no marring of the type observed with the pliers of the '598 patent. The clamping force is substantially constant regardless of the size of the workpiece, but is adjustable in some versions of the pliers. The pliers may be provided with no locking or releasable overcenter locking, or the ability to switch between the two.




In accordance with the invention, a self-adjusting pliers comprises an upper arm including an upper jaw at a first end thereof, an upper handle at a second end thereof, a support extending downwardly from an intermediate location thereof, a first downwardly extending slot in the support, and a second downwardly extending slot in the support. The second downwardly extending slot is parallel to the first downwardly extending slot and closer to the upper handle than the first downwardly extending slot. The second downwardly extending slot has a plurality of second-slot teeth on a side thereof adjacent to the first downwardly extending slot. A lower arm includes a first end thereof, and a lower handle at a second end thereof. A control arm is pivotably connected at a first end to the upper arm and at a second end to the lower arm at an intermediate location between the first end and the lower handle. A spring is affixed at a first end to the upper arm at a location adjacent to the first end thereof, and affixed at a second end to the control arm so as to resist rotation of the control arm. A lower jaw member includes a lower jaw at a first end thereof, the lower jaw being in a facing relationship to the upper jaw, and a slider extending from a side of the lower jaw member. The slider is slidably engaged to the first downwardly extending slot. A pawl is disposed within the second downwardly extending slot and has a set of pawl teeth in facing relationship to the second-slot teeth. A shifter has three pivot points arranged in a triangular pattern, the three pivot points being respectively connected to the lower jaw member, to the pawl, and to the first end of the lower arm.




The lower jaw member is not part of or rigidly fixed to the lower arm. Instead, it slides in the first slot, so that it necessarily produces a controlled, perpendicular clamping force on the workpiece being grasped. The lower jaw member cannot move in a sideways or end-to-end fashion, thereby overcoming a significant fault in some prior self-adjusting pliers. The locking and clamping force is applied by the user's hand force through the two handles and thence through the pawl mechanism acting against the teeth in the second slot and through the rigid-body pivoting shifter. The two functions of the guiding of the movement of the lower jaw member and the application of force are thus separated to ensure that the movement of the lower jaw member is true.




The two slots may be straight or curved. When the two slots are straight, the force applied to the workpiece being grasped is approximately constant, but varies slightly for different sizes of workpieces. When the slots are curved, it is preferred that they have a curvature substantially parallel to a locus of movement of the second end of the control arm as it pivots about its first end. In this case, the force applied to a workpiece is substantially constant for all sizes of workpieces, an important advantage for some applications.




The pliers may be provided with control over the force applied to the workpiece through the jaws. A manual force adjuster acting on the control arm is provided at a location adjacent to the first end of the control arm. The manual force adjuster is operable to move the control arm in a direction along the length of the upper arm. This movement of the first end of the control arm changes its angle and position relative to the lower arm and to the jaw member, with the result that the clamping force applied through the jaws is controllably variable.




The pliers may also be provided with a releasable overcenter lock for the jaws. In this version, there is a downwardly extending lobe on the control arm. A release arm is pivotably connected to the lower arm and has a release pad disposed to contact the lobe of the control arm when the release arm is pivoted. In operation, the control arm moves to an overcenter position when the clamping force is fully applied. This overcenter position may be released to unlock the jaws from the workpiece either by pulling the handles apart, or by manually pivoting the release arm. The overcenter locking is readily released by pulling the handles apart when the clamping force is small, but is more conveniently released by operating the release arm when the clamping force is large.




In another version, the pliers is controllably switchable between a non-locking function and a locking function. A locking function switch is movable between a first position whereat it does not block pivoting movement of the release arm, and a second position whereat it does block pivoting movement of the release arm. The blocking of the movement of the release arm when the locking function switch is in the second position prevents the functioning of the release arm and the movement of the control arm to the overcenter position, and thereby prevents the locking function.




It is preferred to combine the features of the manual force adjuster and the releasable overcenter lock in a single pliers, when either feature is provided.




The clamping mechanism of the invention is operable to move the lower jaw member upwardly along the first downwardly extending slot until the lower jaw contacts the workpiece, thereafter to lock the lower jaw member to the second downwardly extending slot, and to transfer a clamping force to the lower jaw. The clamping mechanism is thus self-adjusting to accommodate any size workpiece that will fit between the jaws. The lower jaw member and the lower jaw are constrained to move along the first slot, independent of the functioning of the locking feature that operates in conjunction with the second slot, ensuring a true movement. Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. The scope of the invention is not, however, limited to this preferred embodiment.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a schematic elevational view of a pliers, with the jaws in the fully open position;





FIG. 2

is a schematic end view of the pliers, from the jaw end;





FIG. 3

is a schematic elevational view like that of

FIG. 1

, after initial activation of the pliers handles;





FIG. 4

is a schematic elevational view like that of

FIG. 1

, at the position where the lower jaw contacts the workpiece;





FIG. 5

is a schematic elevational view like that of

FIG. 1

, as force is applied to the workpiece;





FIG. 6

is a schematic elevational view like that of

FIG. 1

, as the lower handle is pivoted toward an overcenter position; and





FIG. 7

is a schematic elevational view of a second embodiment of the pliers, with force adjustment and a locking release.











DETAILED DESCRIPTION OF THE INVENTION





FIG. 1

illustrates a pliers


20


according to one embodiment of the invention. The figures are all schematic drawings illustrating external features and internal mechanisms in a single plane, for clarity in describing the interrelationships of the elements. “Up” and “down” reference directions are indicated on FIG.


1


. The pliers


20


comprises an upper arm


22


with an upper jaw


24


at a first end


26


of the upper arm


22


. The upper arm


22


has a cross-sectional shape preferably in the form of an inverted “U”, with the opening of the “U” pointing downwardly, as seen in FIG.


2


. (In

FIG. 2

, some elements are omitted for clarity.) The upper jaw


24


preferably has a pattern of gripping ridges


28


on its lower side


30


for engaging a workpiece


32


. An upper handle


34


is at an oppositely disposed second end


36


of the upper arm


22


. The upper handle


34


is configured for comfortable gripping by a user operating the pliers


20


, and may be contoured and/or provided with a resilient plastic covering.




A support


38


is affixed to and extends downwardly from the upper arm


22


at an intermediate location between the first end


26


and the second end


36


. The support


38


desirably includes two parallel and spaced-apart support bodies


38




a


and


38




b


, as seen in FIG.


2


.




Two slots are provided in the support


38


, extending through the support bodies


38




a


and


38




b


. A first slot


40


extends downwardly and has smooth side walls. A second slot


42


extends downwardly parallel to the first slot


40


, at a location rearward of the first slot and thence closer to the upper handle


34


than the first slot


40


. The two slots


40


and


42


are illustrated in

FIG. 1

as curved, and the curvature will be discussed subsequently. They are locally parallel to each other, even though curved. The slots


40


and


42


may instead be straight. A first side


44


of the second slot


42


, closest to the first slot


40


, has second-slot teeth


46


thereon. An oppositely disposed second side


48


of the second slot


42


, closest to the upper handle


34


, is smooth.




A lower arm


50


has a first end


52


and an oppositely disposed second end


54


. The lower arm


50


preferably has a cross section in the form of an upwardly opening “U” shape. A lower handle


56


is present toward the second end


54


. As with the upper handle


34


, the lower handle


56


is configured for comfortable gripping by a user operating the pliers


20


, and may be contoured and/or provided with a resilient plastic covering. Force is applied to the workpiece


32


by the hand of the user of the pliers


20


acting through the two handles


34


and


56


.




A control arm


58


is pivotably connected at a first end


60


thereof to an upper control arm pivot pin


62


on the upper arm


22


at a location within or adjacent to the upper handle


34


. A second end


64


of the control arm


58


is pivotably connected to a lower control arm pivot pin


66


at an intermediate location between the ends


52


and


54


of the lower arm


50


.




A spring


68


is affixed at a first end


70


thereof to the upper arm


22


at a location adjacent to the first end


26


of the upper arm


22


. A second end


72


of the spring


68


is affixed to a spring extension


74


of the control arm


58


. The spring extension


74


extends beyond the portion of the control arm


58


that is affixed to the upper control arm pivot pin


62


, preferably at an angle to the control arm


58


. The preferred angle between the spring extension


74


and the control arm


58


is about


45


degrees, although other angles are operable. The spring force of the spring


68


applied through the spring extension


74


serves to resist rotation of the control arm


58


, in the clockwise direction in the view of FIG.


1


.




The mechanism associated with the upper arm


22


, including the first end


60


of the control arm


58


, the upper control arm pivot pin


62


, the spring


68


, and the spring extension


74


, are hidden from external view within the interior of the U-shaped upper arm


22


. Similarly, the second end


64


of the control arm


58


and the lower control arm pivot pin


66


are hidden from external view within the interior of the U-shaped lower arm


50


.




A lower jaw member


76


includes a lower jaw


78


at a first end


80


thereof. The lower jaw


78


preferably has a pattern of upwardly facing gripping ridges


82


thereon. The gripping ridges


28


and


82


are in facing relationship to each other, and serve to grasp the workpiece


32


firmly therebetween.




A slider


84


extends from each side of the lower jaw member


76


, as seen in

FIGS. 1 and 2

. The slider


84


is shaped to be received within, and to slide within, the first slot


40


. The slider


84


is straight where the first slot


40


is straight, and is curved to match the curvature of the first slot


40


, when the first slot


40


is curved. The slider


84


is dimensioned so that its fit into the first slot


40


is sufficiently loose to prevent binding of the slider


84


to the sides of the first slot


40


during operation. The slider


84


constrains the movement of the lower jaw


78


so that it has a perpendicular or near-perpendicular incidence to the upper jaw


24


when the workpiece is grasped between the jaws. This constraint prevents any end-to-end or side-to-side relative movement of the jaws


78


and


24


, which would tend to gouge the workpiece. This constraint is an important advantage of the present invention, achieved with the use of two slots


40


and


42


, rather than a single slot.




A pawl


86


is captured within and disposed within the second slot


42


of each of the support bodies


38




a


and


38




b


. (That is, there are preferably two pawls


86


, but one pawl would be sufficient for the pliers to operate.) Each pawl


86


has a set of pawl teeth


88


thereon, in facing relationship to the second slot teeth


46


. A second side


90


of the pawl


88


, oppositely disposed from the pawl teeth


88


, is smooth and in facing relationship to the smooth second side


48


of the second slot


42


. The functioning of the pawl


86


will be subsequently discussed in relationship to

FIGS. 3-6

.




A shifter


92


is a plate that transfers force applied to the handles into the lower jaw


78


. There may be two plate shifters


92


, one outside of each of the support bodies


38




a


and


38




b


. Equivalently, there may be a single shifter


92


disposed between the two support bodies


38




a


and


38




b


. Each shifter


92


has three pivot points thereon arranged in a triangular pattern. The three pivot points on the shifter


92


are respectively connected to a lower jaw member pivot pin


94


on the lower jaw member


76


, a pawl pivot pin


96


on the pawl


86


, and a lower arm pivot pin


98


at the first end


52


of the lower arm


50


. The shifter


92


provides the interconnection between the lower arm


50


, the pawl


86


, and the lower jaw member


76


. That is, the lower jaw member


76


is not integral with the lower arm


50


.




A torsion spring


99


is wound around the lower arm pivot pin


98


and anchored on the lower arm


50


. The torsion spring


99


resists rotational movement of the lower arm


50


relative to the lower arm pivot pin


98


.




FIGS.


1


and


3


-


6


provide a sequential depiction of the movement of the mechanism of the pliers


20


from an initial position in

FIG. 1

to a near-final position in FIG.


6


. Not all elements are shown and labeled in

FIGS. 3-6

, so that the operation of the mechanism is not obscured. In

FIG. 1

, the mechanism is in a relaxed, filly open position, with no force applied through the handles


34


and


56


. The workpiece


32


is not yet grasped between the jaws


24


and


78


, the slider


84


is free to slide within the first slot


40


to move the lower jaw member


76


upwardly, and the pawl


86


is free to slide within the second slot


42


with the second side


90


of the pawl


86


sliding along the second side


48


of the second slot


42


.




This configuration is retained, see

FIG. 3

, as a force is applied through the arms


22


and


50


, the lower handle


56


is moved upwardly, thereby acting through the shifter


92


to move the lower jaw member


76


upwardly to approach contact to the workpiece


32


. Simultaneously, the control arm


58


pivots about the upper control arm pivot pin


62


, clockwise in the view of

FIG. 3

, so that the spring


68


extends. The spring extension creates a relatively small force that resists the upward movement of the lower handle


56


, giving the user of the pliers


20


a feel for the positioning and movement of the lower handle


56


. This spring extension force also serves as a restoring force that moves the arms


22


and


50


apart to the jaw-open or relaxed position of the pliers


20


shown in

FIG. 1

, if no force is applied to the handles


34


and


56


.




With continued upward movement of the lower handle


56


, the lower jaw


78


contacts the workpiece so that it can no longer move upwardly, as seen in FIG.


4


. At this point, the continued movement of the lower handle


56


causes the shifter


92


to rotate in rigid-body motion in the clockwise direction in FIG.


4


. The rigid-body rotation of the shifter


92


draws the pawl


86


forwardly, engaging the pawl teeth


88


to the second-slot teeth


46


, as seen in FIG.


5


. This engagement between the sets of teeth


88


and


46


effectively produces a new clamping pivot point, whose location along the second slot


42


varies according to the size of the workpiece


32


. The smaller the workpiece


32


, the further upwardly along the second slot


42


is the point where the sets of teeth


88


and


46


engage. With continued upwardly movement of the lower handle


56


, as in

FIG. 6

, the shifter


92


rotates about this effective clamping pivot point, causing the lower jaw member


76


to rotate about the clamping pivot point and, in cooperation with the upper jaw


24


, to apply clamping force to the workpiece


32


.




In all of this movement depicted in FIGS.


1


and


3


-


6


, the movement of the lower jaw member


76


is constrained by the slider


84


to travel along the first slot


40


. Also during the movement of FIGS.


1


and


3


-


6


, the second end


64


of the control arm


58


follows a locus of points as it pivots about the upper control arm pivot pin


62


. Desirably, the first slot


40


and the second slot


42


are shaped with the same curvature as this locus of points or, alternatively stated, the first slot


40


and the second slot


42


are parallel to the locus of points defined by the second end


64


. With this preferred configuration for the slots


40


and


42


, the clamping force applied to the workpiece


32


is the same, regardless of the size of the workpiece


32


. The closer the curvature of the slots


40


and


42


to that of the locus of points of the second end


64


, the closer is the clamping force to a constant value for all workpiece sizes that fit between the jaws


24


and


78


. Even if the slots


40


and


42


are straight, the variation in the clamping force is relatively small, so that straight slots


40


and


42


may be used if it is not important to maintain the clamping force exactly constant.





FIG. 7

depicts an embodiment of the pliers


20


that provides for both adjustability of the clamping force applied through the jaws


24


and


78


, and also for overcenter locking and release of the clamping force. These two features of force adjustability and overcenter locking and release are desirably provided together, but they may be provided separately. The basic closing and opening mode of this pliers


20


of

FIG. 7

is the same as that shown in

FIGS. 1-6

. Features common to the embodiment of

FIGS. 1-6

are identified by the same numerals, and the prior discussion of

FIGS. 1-6

is incorporated herein.




The clamping force adjustability is provided by moving the upper control arm pivot pin


62


in a track


100


in the upper arm


22


, along the length of the upper arm


22


in the direction between the first end


26


and the second end


36


. The maximum travel required to achieve a substantial variation in the clamping force is relatively small, and typically is about ¼ inch. The movement of the upper control arm pivot pin


62


along the track


100


is accomplished with a screw drive


102


and a manual screw movement knob


104


that extends from the second end


36


of the upper arm


22


.




The overcenter locking and release is conveniently provided by placement of an unlocking lobe


106


on the lower side of the control arm


58


. A release arm


108


is pivotably connected to the lower arm


50


, at a location between the first end


52


and the second end


54


and accessible to the hand of the user of the pliers


20


at the second end


54


. A release pad


110


on the upper side of the release arm


108


is disposed to contact the unlocking lobe


106


. In operation, the lower control arm pivot pin


66


moves to an overcenter position relative to the upper control arm pivot pin


62


and the lower arm pivot pin


98


, when the lower handle


56


is moved upwardly to the limit of its travel. Stated alternatively, when the lower handle


56


is fully open (moved to its downward limit of travel) as in

FIG. 1

, the lower control arm pivot pin


66


lies below a straight line drawn between the upper control arm pivot pin


62


and the lower arm pivot pin


98


. As the lower handle


56


is moved upwardly, the lower control arm pivot pin


66


moves closer to a straight-line relationship between the pins


62


and


98


, and eventually crosses over that straight line to lie above the straight line drawn between the pins


62


and


98


. This is the overcenter lock position. To release the pliers


20


from this overcenter lock position, the release arm


108


is operated to rotate the release pad


110


upwardly against the unlocking lobe


106


, and thereby force the lower arm


50


downwardly and out of the overcenter relationship.




The embodiment of

FIG. 7

allows the pliers


20


to be selectively shifted between the non-locking version and the locking/release version. A lock switch


112


is provided to selectively prevent the pivoting movement of the release arm


108


. That is, when the movement of the pliers


20


passes into the overcenter relationship, the release arm


108


is forced to pivot in the direction (counter-clockwise in the embodiment of

FIG. 7

) opposite to the pivoting movement of the release arm


108


during unlocking (clockwise in FIG.


7


). The locking function may be prevented by preventing this movement of the release arm


108


as the movement reaches the overcenter position as the jaws are closed, so that the stationary release arm


108


prevents the movement of the control arm


58


from passing to the overcenter position. The lock switch


112


prevents the movement of the release arm


108


and the control arm


58


by physically contacting and interfering with the movement of the release arm


108


. Thus, in the embodiment of

FIG. 7

, the lock switch


112


slides into an interfering position relative to the release arm


108


when slid to the right, so that the overcenter locking is not permitted. The pliers then serves as an ordinary non-locking pliers. When the lock switch


112


is slid to the left in the view of

FIG. 7

, it does not interfere with the rotation of the release arm


108


, and the release arm


108


does not prevent the movement of the lobe


106


and thence the control arm


58


as it passes to the overcenter position. The pliers is a locking pliers in this configuration.




Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.



Claims
  • 1. A self-adjusting pliers, comprising:an upper arm including an upper jaw at a first end thereof, an upper handle at a second end thereof, a support extending downwardly from an intermediate location thereof, a first downwardly extending slot in the support, and a second downwardly extending slot in the support, the second downwardly extending slot being parallel to the first downwardly extending slot and closer to the upper handle than the first downwardly extending slot, the second downwardly extending slot having a plurality of second-slot teeth on a side thereof adjacent to the first downwardly extending slot; a lower arm including a first end thereof, and a lower handle at a second end thereof; a control arm pivotably connected at a first end to the upper arm and at a second end to the lower arm at an intermediate location between said first end of said lower arm and said lower handle; a spring affixed at a first end to the upper arm at a location adjacent to said first end of said upper arm, and affixed at a second end to the control arm so as to resist rotation of the control arm; a lower jaw member including a lower jaw at a first end thereof, the lower jaw being in a facing relationship to the upper jaw, and a slider extending from a side of the lower jaw member, the slider being slidably engaged to the first downwardly extending slot; a pawl disposed within the second downwardly extending slot, the pawl having a set of pawl teeth in facing relationship to the second slot teeth; and a shifter having three pivot points arranged in a triangular pattern, the three pivot points being respectively connected to the lower jaw member, to the pawl, and to the first end of the lower arm.
  • 2. The pliers of claim 1, wherein the first slot and the second slot are straight.
  • 3. The pliers of claim 1, wherein the first slot and the second slot are curved.
  • 4. The pliers of claim 1, wherein the first slot and the second slot are curved with a curvature substantially parallel to a locus of movement of the second end of the control arm as it pivots about its first end.
  • 5. The pliers of claim 1, further includinga manual adjuster means acting on the control arm at a location adjacent to said first end of said control arm, and operable to move the control arm in a direction along the length of the upper arm between the first end and the second end of the upper arm.
  • 6. The pliers of claim 1, further includinga downwardly extending lobe on the control arm, and a release arm pivotably connected to the lower arm and having a release pad disposed to contact the lobe of the control arm when the release arm is pivoted.
  • 7. The pliers of claim 6, further includinga lock switch slidable movable between a first position whereat it does not block pivoting movement of the release arm, and a second position whereat it does block pivoting movement of the release arm.
  • 8. The pliers of claim 1, further includinga manual adjuster means acting on the control arm at a location adjacent to said first end of said control arm, and operable to move the control arm in a direction along the length of the upper arm between the first end and the second end of the upper arm, a downwardly extending lobe on the control arm, and a release arm pivotably connected to the lower arm and having a release pad disposed to contact the lobe of the control arm when the release arm is pivoted.
  • 9. The pliers of claim 8, further includinga locking function switch slidably movable between a first position whereat it does not block pivoting movement of the release arm, and a second position whereat it does block pivoting movement of the release arm.
  • 10. The pliers of claim 9, wherein the locking function switch is slidably movable.
  • 11. A self-adjusting pliers operable to grasp a workpiece between an upper jaw and a lower jaw, comprising:an upper arm including the upper jaw; a lower arm; a support extending downwardly from the upper arm toward the lower arm; a first downwardly extending slot in the support; a second downwardly extending slot in the support; a control arm pivotably connected at a fist end to the upper arm and at a second end to the lower arm at an intermediate location of said lower arm; a spring biasing the control arm so as to resist rotation of the control arm; a lower jaw constrained to slide along the first downwardly extending slot, the lower jaw not being integral with the lower arm; and a clamping mechanism operable to move the lower jaw along the first downwardly extending slot until it contacts the workpiece, thereafter to lock the lower jaw to the second downwardly extending slot, and to transfer a clamping force to the lower jaw.
  • 12. The pliers of claim 11, wherein the first downwardly extending slot is parallel to the second downwardly extending slot.
  • 13. The pliers of claim 11, wherein the first downwardly extending slot and the second downwardly extending slot are parallel.
  • 14. The pliers of claim 11, further includinga manual adjuster means acting on the control arm and operable to move a pivot point at the first end of the control arm in a direction along the length of the upper arm.
  • 15. The pliers of claim 11, further includinga downwardly extending lobe on the control arm, and a release arm pivotably connected to the lower arm and having a release pad disposed to contact the lobe of the control arm when the release arm is pivoted.
  • 16. The pliers of claim 15, further includinga lock switch slidable movable between a first position whereat it does not block pivoting movement of the release arm, and a second position whereat it does block pivoting movement of the release arm.
US Referenced Citations (8)
Number Name Date Kind
4541312 Petersen Sep 1985
4651598 Warheit Mar 1987
4662252 Warheit May 1987
4730524 Petersen Mar 1988
4802390 Warheit Feb 1989
4922770 Dlugolecki et al. May 1990
5020399 Annis et al. Jun 1991
5408904 Neff Apr 1995