Abstract:
A pair of locking pliers having an adjusting device that utilizes a cam assembly. The pliers, preferably, include a trolley disposed in a first handle member that defines a channel. The trolley is structured to be coupled to a link assembly wherein the position of the link assembly relative to the distal end of the first handle member affects the spacing of the pliers&#39; jaws. The cam assembly is, preferably, a planar disk-like body having a radially extending handle and, preferably, a plurality of flats about the circumference. The cam assembly is disposed, preferably, in the plane defined by the first handle member and the second handle assembly. The cam is coupled to the first handle member at the distal end of the handle portion and its&#39; axis extends generally perpendicular to the plane defined by the first handle member and the second handle assembly. At this location, the cam plurality of flats are structured to engage the trolley/cam follower as the cam handle extends beyond the first handle member distal end. Rotation of the cam causes the trolley, and therefore link assembly, to move relative to the distal end of the first handle member.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/916,417, filed May 7, 2007, and entitled “locking Pliers with CAM.” 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to locking pliers and, more specifically to a cam incorporated into the locking assembly of the pliers. 
   2. Background Information 
   Traditional pliers have, generally, two elongated members each having a handle at one end and a jaw at the other. The members cross over each other and are coupled at a single, medial pivot in a manner similar to scissors. Locking pliers, as used herein, have at least four primary members: a first member, that is a combined jaw/handle, a second jaw member, a second handle assembly, and one or more linking members. The second jaw member is pivotally coupled to the first member adjacent to the jaw so that the jaw members may close together. The second handle assembly is pivotally coupled to the second jaw member. The linking member extends between the first handle member and the second handle assembly. More specifically, the linking member extends from the distal end of the first handle member to a location adjacent to the pivot coupling of the second jaw and second handle assembly. 
   Thus, the first member jaw portion and the second jaw may be moved between a first, open position and a second, closed position. The second handle and the linking member also move between respective first positions and second positions corresponding to the position of the jaws. When the components of the locking pliers are in their respective first positions, the pliers are in a first, open configuration. Similarly, when the components of the locking pliers are in their respective second positions, the pliers are in a second, closed configuration. The locking pliers typically have one or more springs structured to bias the locking pliers to the first configuration. 
   Locking pliers may have improved operational capabilities by reconfiguring the elements or adding additional links to provide for an enhanced closing motion. For example, in one improvement the second handle assembly may be coupled to the first member adjacent to the jaw, and, a second linking member extends from the second handle assembly to the second jaw. With this addition, the line of force acting on the second linking member/second jaw coupling is generally more tangent to the first member/second jaw pivot and, as such, enhances the force applied by the user when compared to the configuration identified above. 
   It is further noted that, in this configuration, the jaws have a limited range of motion. Thus, if the jaws are far apart in the first position, the jaws may not be able to close completely when the handles are moved into the second position. Alternatively, if the jaws are close together in the first position, the jaws may not be able to extend around a larger object. To overcome this disadvantage locking pliers typically have a longitudinally adjustable coupling between the linking member and the first member. That is, the first handle member portion typically has a U-shaped cross-section that acts as a channel. The distal end of the first handle member portion is closed off with a generally flat flange. A first end of the linking member is slidably disposed in the channel. The location of the linking member first end relative to the first handle member portion is typically made adjustable by having a threaded rod extend through the flange. As the threaded rod, which has an external head/handle, is moved into the first handle member portion, the location of the linking member first end is adjusted toward the first member jaw portion. Generally, the closer the linking member first end is to the first member jaw portion, the closer the jaws are when in the first position. 
   Further, the geometry of the linking member(s) may be structured so as to act as a toggle when the pliers move into the second, closed position. That is, as the handles are moved together, the linking member will move “over-toggle” and become locked relative to the second handle assembly. If the jaws are engaging an object, the pliers will become locked about that object. With regard to the toggle, the movement of the threaded rod adjusts the location that the linking member moves over toggle and become locked. 
   Thus, in operation, a user typically begins with the threaded rod extended relatively far, if not as far as possible, from the first handle member portion. In this configuration, the jaws are more separated than when the threaded rod is moved into the first handle member portion. When the user draws the handles together, the jaws close and, if the jaws were initially too far apart, the user can estimate about how far to move the threaded rod for a better, tighter fit or to set the point where the linking member moves over-toggle and locks the pliers to the object. Alternatively, a user may move the pliers into the second position around an object and then use the threaded rod, that is, insert the threaded rod into the first handle member portion, to lock the pliers in place. 
   The disadvantage to using a threaded rod is that manipulation of the threaded rod is slow and requires dexterity on the part of the user. Generally, the user must grasp and twist the threaded rod with their fingers. Thus, in most instances, the user must hold the pliers with one hand while manipulating the threaded rod with the other hand. This can be particularly disadvantageous when the user is, for example, attempting to grip two or more heavy objects in the jaw and then lock the jaw. In such an instance, the user must be strong and quick or the user is likely to loose their grip. 
   SUMMARY OF THE INVENTION 
   The concept disclosed herein provides for a locking pliers adjusting device that utilizes a cam assembly. The pliers, preferably, include a trolley disposed in the first handle member portion channel. The trolley is structured to be coupled to the linking member and to act as a cam follower. The cam assembly is, preferably, a planar disk-like body having a radially extending handle and, preferably, a plurality of flats about the circumference. The cam assembly is disposed, preferably, in the plane defined by the first handle member and the second handle assembly. The cam assembly further has an axis. The axis is coupled to the first member at the distal end of the handle portion and extends generally perpendicular to the plane defined by the first handle member and the second handle assembly. At this location, the cam plurality of flats are structured to engage the trolley/cam follower as the cam handle extends beyond the first handle member distal end. 
   The cam plurality of flats are structured so that each flat is a different radial distance from the cam axis. Preferably, the radii of the flats increases/decreases in series. Thus, for example, on a cam with four flats, a first flat may be the closest to the axis; the second flat is at a slightly greater radial distance from the axis than the first flat; the third flat is at a slightly greater radial distance from the axis than the second flat; and the fourth flat is at the greatest radial distance from the axis. Between each flat is a rounded transition. In this configuration, the location of the trolley relative to the first handle member portion, and thus the location of the linking member first end relative to the first handle member portion and the spread of the jaws in the first position, is controlled by the cam. That is, when the cam first flat engages the trolley, the trolley is disposed close to the cam axis and the distal end of the first handle member portion. Thus, when the pliers are in the first configuration, the jaws are spaced a first distance apart. Conversely, when the cam fourth flat engages the trolley, the trolley is disposed far from the cam axis and the distal end of the first handle member portion. Thus, when the pliers are in the first configuration, the jaws are spaced a fourth distance apart which is a shorter distance than the first distance. There are intermediate positions for the trolley, with corresponding jaw spacing distances, when the trolley engages the second and third flats. 
   Because the position of the cam is controlled by the handle, a user may quickly adjust the cam to a desired position. That is, unlike the prior art threaded rod that must be grasped by the users fingers, the cam handle may be moved by a single finger, the back of the hand, and so forth. Such a device for adjusting the trolley is much faster and more efficient than a threaded rod. 
   While a cam having flats is preferred, it is noted that the cam may also have an outer surface with a gradually increasing radius. That is, when the trolley/cam follower engages a flat on the cam, and in response to the bias created by the locking pliers spring, the cam will be generally maintained in the set position by the bias of the trolley as the trolley engages the flat. Thus, the cam with flats is preferred as the cam is less prone to rotate unintentionally. However, a cam with a generally smooth radial surface provides an, essentially, infinite number of trolley positions between the minimum and maximum radii of the cam. To avoid having this embodiment of the cam slip, the cam may have, for example, a friction fit between the axle and the distal end of the first handle member portion. That is, where the axle is rotatably disposed in a snug opening within the distal end of the first handle member portion, the cam will resist turning freely about the axle. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which: 
       FIG. 1  is a side view of the locking pliers. 
       FIG. 2  is an isometric and cutaway view of the locking pliers. 
       FIG. 3  is a detailed cross-sectional view of the cam in a first position. 
       FIG. 4  is a detailed cross-sectional view of the cam in a second position. 
       FIG. 5  is a detailed cross-sectional view of the cam in a third position. 
       FIG. 6  is a detail cross-sectional view of the cam in a fourth position. 
       FIG. 7  is a detailed side view of the cam. 
       FIG. 8  is a side view of an alternate embodiment wherein the cam has a gradually increasing radius. 
   

   DETAILED DESCRIPTION 
   As used herein, the “radius” of a flat portion located on the periphery of a generally circular body means the distance from the center of the body to the middle of the flat portion. 
   As used herein, “coupled” means a link between two or more elements, whether direct or indirect, so long as a link occurs. 
   As used herein, “directly coupled” means that two elements are directly in contact with each other. 
   As used herein, “fixedly coupled” or “fixed” means that two components are coupled so as to move as one while maintaining a constant orientation relative to each other. 
   As used herein, the word “unitary” means a component is created as a single piece or unit. That is, a component that includes pieces that are created separately and then coupled together as a unit is not a “unitary” component or body. 
   As shown in  FIGS. 1 and 2 , a pair of locking pliers  10  has a first assembly  12 , that includes an elongated first handle member  14  and a first jaw member  16 , an elongated second handle assembly  18 , a second jaw member  20 , and a link assembly  22  having at least one link  24 . As shown, the link assembly  22  includes an upper link  30  and a lower link  32 . As is known in the art, the locking pliers  10  may be made from a plurality of laminations wherein one component may be disposed on both sides of another component. That is, one component may “sandwich” another component. Typically, it does not matter which of the components has the two layers and which component has the single layer. For example, as shown in  FIG. 2 , the first jaw member  16  has two layers that sandwich the second jaw member  20 . However, it is understood that the construction could be reversed with the second jaw member  20  sandwiching the first jaw member  16  (not shown). In view of the reversible nature of which component sandwiches which, the following discussion shall address the locking pliers  10  without reference to a specific construction of layers. That is, as set forth above, a component will simply be named, e.g., the a first jaw member  16 , without detailing which components have one layer and which components have two, or more, layers. 
   The first assembly  12  is generally rigid. That is, the first handle member  14  and a first jaw member  16  are fixed together and, as shown, are preferably formed from a unitary body. The first handle member  14  has a proximal end  34  fixed to the first jaw member  16  and a distal end  36 . The first handle member distal end  36  defines a generally longitudinal channel  38 . The cam assembly  100 , discussed below, is substantially disposed in the first handle member channel  38 . 
   The first jaw member  16  includes a rack  40  disposed in a cutout  42 , a pawl  44 , a race  46 , and a slider  48 . The pawl  44  is movably disposed in the cutout  42  and structured to move longitudinally therein and to engage the rack  40 . The slider  48  is slidably disposed in the race  46  and structured to move longitudinally therein. Further, the first jaw member  16  has an upper end defining a first jaw element  50 . The first jaw element  50  has a generally straight portion with a plurality of gripping teeth  52 . 
   The second jaw member  20  has a body with an upper portion  60  and a lower portion  62 . The second jaw member upper portion  60  defines a second jaw element  64  having a generally straight portion with a plurality of gripping teeth  66 . The second jaw element  64  is sized and shaped to generally correspond to the size and shape of the first jaw element  50 . The second jaw member lower portion  62 , preferably, has a greater width than the second jaw member upper portion  60  and thereby provides coupling points for the other components of the locking pliers  10 . 
   The second handle assembly  18  includes an elongated handle member  70 , a proximal pivotal coupling  72  and a medial pivotal coupling  74 . The second handle assembly handle member  70  has a proximal end  76  and a distal end  78 . The second handle assembly proximal pivotal coupling  72  is disposed at the second handle assembly handle member proximal end  76 . 
   As noted above, the link assembly  22  in the embodiment shown includes an elongated first, upper link  30  and an elongated second lower link  32 . Both the first and second links  30 ,  32  have first, upper ends  84 ,  88  and second, lower ends  86 ,  90 , respectively. Each of the link ends  84 ,  86 ,  88 ,  90  are structured to be pivotally coupled to another component. The first link  30  further includes a medial pivot coupling  92  disposed between the first link first end  84  and the first link second end  86 . As shown, the medial pivot coupling  92  is disposed closer to the first link second end  86 . As discussed below, the first link  30  and the second link  32  are pivotally coupled together and are structured to move between a first, open position and a second over-toggle position. 
   The locking pliers  10  are assembled as follows. The second jaw member  20  is pivotally coupled to the first jaw member  16 . More specifically, the pawl  44  is pivotally coupled to the second jaw member lower portion  62 . The second handle assembly handle member  70 , and more specifically the proximal pivotal coupling  72 , is pivotally coupled to the slider  48 . The first link first end  84  is pivotally coupled to the second jaw member lower portion  62 . The first link medial pivot coupling  92  is pivotally coupled to the second handle assembly medial pivotal coupling  74 . The first link second end  86  is pivotally coupled to the second link first end  88 . The second link second end  90  is pivotally coupled to the cam assembly  100 , discussed below. 
   In this configuration, the second jaw member  20  is structured to move between a first, open position, wherein the first jaw element  50  and the second jaw element  64  are spaced from each other, and a second position, wherein the first jaw element  50  and the second jaw element  64  are closer to, or in contact with, each other. The jaw elements  50 ,  64  move in response to a relative motion between the first assembly first handle member  14  and the second handle assembly handle member  70 . That is, the first assembly first handle member  14  and the second handle assembly handle member  70  also move between a first, open position, wherein the first assembly first handle member  14  and the second handle assembly handle member  70  are spaced from each other, and a second position, wherein the first assembly first handle member  14  and the second handle assembly handle member  70  are closer to, or in contact with, each other. It is noted that the motion of the second handle assembly handle member  70  is transferred to the second jaw member  20  via the link assembly  22 . Further, it is noted that when the jaw elements  50 ,  64  and the handle members  14 ,  70  are in the open positions, the link assembly  22  is also in an open position. When the jaw elements  50 ,  64  and the handle members  14 ,  70  are in the closed positions, the link assembly  22  is in an over-toggle position, whereby the link assembly  22  acts to lock the locking pliers  10 . A spring (not shown) extends between the link assembly  22  and the first assembly first handle member  14  and biases the jaw elements  50 ,  64  and the handle members  14 ,  70  to the first, open positions. 
   The cam assembly  100  is structured to move the location of the coupling between the second link second end  90  relative to the first jaw member  16 . Moreover, the proximity of the at least one link to the distal end of the first handle member  14  affects the spacing of the jaw members. That is, the position of the second jaw member  20  relative to the first jaw element  50  in the open position changes as the at least one link moves relative to the first handle distal end. Generally, the closer the coupling between the second link second end  90  is to the first jaw member  16 , the closer the first link  30  is to the second jaw member lower portion  62  and the closer the second jaw element  64  is to the first jaw element  50 . To provide for this adjustable motion, the cam assembly  100  includes a trolley  102  and a cam  104 . 
   The trolley  102  has a body  106  sized to fit within the first handle member channel  38 . The trolley body  106  has a coupling extension  108  and a cam follower  110 . Preferably, the cam follower  110  is one side of the trolley body  106 . The cam  104  has a disk-like body  112  with an axis of rotation  113  and a radially extending handle  114 . Preferably, the radial surface  116  of the cam body  112  includes a plurality of flats  118 . Each flat  118  is disposed at a different radial distance from the center of the cam disk-like body  112 . Further, it is desirable that the radii of the flats  118  increases/decreases in series. Thus, as shown, there may be four flats  118 A,  118 B,  118 C, and  118 D. The first flat  118 A is, preferably, the closest to the axis  113 , the second flat  118 B is at a slightly greater radial distance from the axis  113  than the first flat  118 A, the third flat  118 C is at a slightly greater radial distance from the axis  113  than the second flat  118 B, and the fourth flat  118 D is at the greatest radial distance from the axis  113 . Preferably, the first flat  118 A has a radius of between about 0.18 and 0.22 and more preferably about 0.20 inch. Further, each successive flat  118 B,  118 C,  118 D has a radius that is about 0.02 inches further from the axis  113  than the prior flat  118 . Between each flat  118  is a rounded transition  120 . 
   The cam assembly  100  is assembled as follows. The cam  104  is rotatably coupled to the first assembly first handle member distal end  36  and structured to engage said trolley cam follower  110 . The cam axis  113  extends generally perpendicularly to the longitudinal axis of the first handle member  14 . Further, the cam radial surface  116  is disposed at least partially within the channel  38 . The cam handle  114  extends from the first assembly first handle member distal end  36 . The trolley  102  is disposed within the first handle member channel  38  and the trolley cam follower  110  is structured to engage the cam radial surface  116 . The user may rotate the cam  104  on the axis  113  by moving the cam handle  114 . Thus, the trolley  102  is structured to slide between a plurality of positions relative to the cam  104 . In the preferred embodiment, where the cam  104  has four flats  118 A,  118 B,  118 C,  118 D, the trolley  102  is structured to move between four corresponding positions. The second link second end  90  is pivotally coupled to the trolley body coupling extension  108 . Thus, the second link second end  90  also moves between a plurality of positions relative to the cam  104 . As noted above, the position of the second link second end  90  affects the spacing of the first and second jaw elements  50 ,  64 . 
   That is, when the handle members  14 ,  70  are in the first position and cam first flat  118 A, with the minimum radius, engages the trolley cam follower  110 , the trolley  102  is disposed as close to the first handle member distal end  36  as possible and the jaw elements  50 ,  64  are as far apart as possible. The user may utilize the cam handle  114  to rotate the cam  104  so that a different flat  118 B,  118 C,  118 D engages the trolley cam follower  110 . When a flat  118 B,  118 C,  118 D with a greater radius than the first flat  118 A engages the trolley cam follower  110 , the jaw elements  50 ,  64  will be disposed closer together. 
   It is noted that, unlike the prior art screw-like adjusting device, the cam assembly  100  may be used to quickly change the position of the trolley  102  relative to the first handle member distal end  36  and a one-handed adjustment is possible. That is, because the cam assembly  100  includes the cam handle  114 , the movement of the cam  104  between positions is easily accomplished. Further, the rounded transitions  120  between the flats  118 A,  118 B,  118 C,  118 D ensures that cam  104  does not catch upon the trolley cam follower  110 . 
   In an alternate embodiment, shown in  FIG. 8 , the cam  104 A has a generally smooth radial surface  116 A having an arcuate portion  130  wherein the radius changes between a minimum radius  132  at one location to a maximum radius  134  at another location. Preferably, the arcuate portion  130  extends over about 75 and 105 degrees, and more preferably about ninety degrees. Preferably, the cam  104 A has a minimum radius  132  of between about 0.18 and 0.22 inch and more preferably about 0.20 inch, and, a maximum radius  134  of between about 0.24 and 0.28 inch and more preferably about 0.26 inch. Preferably, the arcuate portion  130  radius changes at a generally constant rate. 
   The cam  104 A in this embodiment is coupled to the first assembly first handle member distal end  36  and engages the trolley cam follower  110  as described above. The cam  104 A may be coupled to the first assembly first handle member distal end  36  with a frictional mounting  140  structured to resist rotational motion of the cam  104 A. That is, the frictional mounting  140  is structured to resist the cam  104 A from rotating freely even when the jaw elements  50 ,  64  are in the open position. The friction created by the frictional mounting  140  may be overcome by applying force to the cam handle  114 . Thus, the frictional mounting  140  allows the user to place, and keep, the cam  104 A in a selected position until the user reorients the cam  104 A. The cam  104 A with a variable radius provides, essentially, infinite variations to the spacing of the jaw elements  50 ,  64  in the open position. 
   While illustrative embodiments of the invention are disclosed herein, it will be appreciated that numerous modifications and other embodiments may be devised by those skilled in the art. Therefore, it will be understood that the appended claims are intended to cover all such modifications and embodiments that come within the spirit and scope of the present invention.