Abstract:
A folding multipurpose tool including adjustable locking pliers with an over-center locking mechanism to retain the jaws in a gripping condition. The jaws of the locking pliers can be folded into the handles of the tool to produce a compact folded configuration. A latch mechanism in the tool handle retains a selected one of several folding tool bits or blades in an extended position for use and includes an abutment arrangement to prevent such a selected tool bit from being extended too far. A spring associated with a tool bit driving socket retains separate tool bits and resists inadvertent removal of an adjustment screw element of the locking pliers. Upon removal of the adjustment screw element, special bits, such as a corkscrew, can be screwed into the tool bit driving socket.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation of U.S. patent application Ser. No. 10/643,098, filed Aug. 18, 2003, now U.S. Pat. No. 7,039,974, which is a division of U.S. patent application Ser. No. 09/816,622, filed Mar. 23, 2001, now U.S. Pat. No. 6,691,357, which is a division of U.S. patent application Ser. No. 09/240,204, filed Jan. 29, 1999, now U.S. Pat. No. 6,282,996. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to multipurpose hand tools, and in particular to such a tool which has over-center locking pliers and can be folded into a compact configuration. 
   Folding multipurpose hand tools have become well known in recent years. Representative tools of this sort are disclosed in, for example, Leatherman U.S. Pat. No. 4,238,862, Leatherman U.S. Pat. No. 4,888,869, Sessions et al. U.S. Pat. No. 5,212,844, Frazer U.S. Pat. No. 5,267,366, MacIntosh U.S. Pat. No. 5,697,114, Hardiner et al. U.S. Pat. No. 5,791,002 and Frazer U.S. Pat. No. 5,809,599. While many of such tools have included folding pliers, only Thai U.S. Pat. No. 5,029,355 discloses pliers capable of being locked by an over-center locking arrangement, and whose jaws can be folded to make such a tool more compact. The Kershaw Multi-Tool™, now on the market, has over-center locking pliers, but the jaws do not fold. Of course, the best known of locking pliers is the Peterson Vise-Grip7, but it is not foldable for compact storage, nor is it multipurpose. 
   Previously-known multipurpose tools with over center locking pliers have been of operable design, but have lacked strength, or useful features, or have been unattractive in appearance, or have not been able to be folded into a suitably compact configuration; and thus such tools have been less than completely satisfactory for their intended purpose. 
   In multipurpose folding tools, various latch mechanisms have been utilized in the past, as represented, for example, by Seber et al. U.S. Pat. No. 5,765,247, and Swinden et al. U.S. Pat. No. 5,781,950, to retain folding tool bits and blades in desired positions, either folded and stowed within a cavity provided in a tool handle, or rigidly and safely extended ready for use. The previously available latching arrangements, however, have had various drawbacks, either from the standpoint of operability, strength, and reliability, or from the standpoint of manufacturing costs. 
   Socket wrenches and hex bit drivers are well known. Adaptors to connect hex bits or sockets or both to multipurpose tools are also well known. See, for example, Heldt U.S. Pat. No. 4,519,278, Chen U.S. Pat. No. 5,033,140, Lin U.S. Pat. No. 5,251,353, Park U.S. Pat. No. 5,280,659, and Cachot U.S. Pat. No. 5,809,600. Tool bit drive adaptors, however, are an additional item which must be carried and kept together with the multipurpose tool to enable it to be used to drive such tool bits. Also, currently available drivers do not work well with special bits, such as corkscrews, which must be pulled, rather than pushed, in use. 
   What is desired, then, is an improved folding multipurpose tool including pliers with over-center locking jaws capable of exerting significant gripping force and whose jaws can be folded. Also desired are a folding multipurpose tool including an improved mechanism for locking and unlocking various blades, and a folding multipurpose tool including an improved holder for hex bit tools. Preferably, such a tool should be of sturdy, reliable construction, be able to be manufactured at a reasonable cost, and have a pleasing appearance, and be capable of folding into a compact storage configuration so as to be easily carried and readily available for use when needed. Also preferable in such a tool is that most of the motions and positionings of the various components that are required when using the tool occur automatically or are intuitive to the user. 
   SUMMARY OF THE INVENTION 
   The present invention overcomes some of the aforementioned shortcomings of the prior art and answers some of the aforementioned needs by providing a folding multipurpose tool incorporating adjustable locking pliers jaws that can be extended into an operational configuration in which the tool may be adjusted to grip objects of different sizes and may be locked by an over-center mechanism while still providing gripping force against an object or objects located between the jaws. 
   In one preferred embodiment of such a tool a pair of jaws are mounted on a jaw pivot shaft on one end of a first handle, and a corresponding end of a second handle is removably connected to a lower one of the jaws to control its movement toward an upper one of the jaws. 
   In one preferred embodiment of the invention, a jaw-moving linkage includes a pair of struts extending between the handles, and the jaws extend between the struts when the tool is folded into a compact folded configuration. 
   As another separate aspect of the present invention, a folding tool including locking pliers has a jaw-moving linkage including a thrust body which interconnects a portion of the jaw-moving linkage to one jaw of the pliers through a pivot joint including mating concave and convex surfaces contacting each other, through which the jaw-moving linkage pushes against a heel portion of that jaw. 
   In one embodiment of that aspect of the invention a spring detent arrangement is provided to keep the pivot joint assembled as desired but permit it to be disconnected easily in order to fold the jaws into the handle to place the tool into its compact folded configuration. 
   Another separate aspect of the present invention is to provide a latch mechanism to retain one or more folding blades or tool bits in a selected position with respect to a handle of a multipurpose folding tool. 
   In a preferred embodiment of this aspect of the invention such a mechanism includes a latch release lever carried on a pivot in a channel-configured portion of one of the handles, and a spring formed as a portion of the handle keeps a catch body carried on the latch release lever engaged with at least one of the blades. 
   In one preferred embodiment of this aspect of the invention each of the blades includes a base portion defining a notch from which the catch body can be released to permit the blade to be moved between its folded and extended positions, while the catch body still prevents the blade from being moved beyond its intended extended position, and the handle and the latch release lever cooperate to prevent the catch body from moving beyond its intended blade-releasing position. 
   Yet another separate aspect of the present invention is that it provides a tool bit drive socket, with a threaded bore at an inner end of the socket, allowing the tool bit drive socket to receive not only conventional tool bits but also special bits threaded at one end. 
   The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE SEVERAL DRAWINGS 
       FIG. 1  is a perspective view of a folding multipurpose tool that is a preferred embodiment of the present invention, with the locking pliers jaws in an extended and operational configuration. 
       FIG. 2  is a right side elevational view of the folding tool shown in  FIG. 1  in a compact fully folded configuration. 
       FIG. 3  is a top plan view of the tool shown in  FIGS. 1 and 2 , in the fully folded configuration shown in  FIG. 2 . 
       FIG. 4  is a left side elevational view of the folding tool in the fully folded configuration shown in  FIG. 2 . 
       FIG. 5  is a bottom plan view of the folding tool in the fully folded configuration. 
       FIG. 6  is a right side elevational view of the folding tool shown in  FIG. 1 , with its handles separated as a first step in moving the jaws of the locking pliers to change the tool from the fully folded configuration into an extended and operational configuration. 
       FIG. 7  is a view of the tool showing the next step of placing the locking pliers jaws into their operational configuration. 
       FIG. 8  is a side elevational view of the folding tool showing the next step in readying the locking pliers of the tool for use, and showing several folding tool blades carried in the second handle of the tool. 
       FIG. 8A  is a side elevational view of the folding tool in an operational configuration with the jaws of the adjustable locking pliers open, ready for use. 
       FIG. 9  is a side elevational view of the folding tool, in the operational configuration with the jaws closed as shown in  FIG. 1 . 
       FIG. 10  is a section view taken along line  10 - 10  of  FIG. 9 . 
       FIG. 11  is a top plan view taken in the direction of line  11 - 11  in  FIG. 9 , showing the strut assembly and the lower handle portion of the tool, but omitting the upper handle and the folding tool blades shown in  FIG. 8 , for the sake of clarity. 
       FIG. 11A  is an isometric view showing the strut assembly from the upper right rear. 
       FIG. 12  is a partially cutaway side elevational view of the jaws of the locking pliers, together with a portion of the upper handle of the tool. 
       FIG. 13  is a section view of the upper handle and portions of the pliers jaws of the tool, taken along line  13 - 13  of  FIG. 12 . 
       FIG. 14  is a view of a portion of one of the pliers jaws of the tool, taken in the direction of line  14 - 14  of  FIG. 12 . 
       FIG. 15  is a view of a portion of the tool, taken in the same direction as  FIG. 9 , but with portions of the handles cut away to disclose the operational relationships among elements of the tool located within the handles. 
       FIG. 15A  is an isometric view of a thrust block and detent spring, from the upper right front of the tool, showing a part of the strut assembly in phantom line. 
       FIG. 16  is a detail view taken in the same direction as  FIG. 15 , at an enlarged scale, showing a thrust block and a portion of the lower handle, together with a heel portion of the lower jaw. 
       FIG. 17  is a view similar to  FIG. 16 , but showing the thrust block detachably connected to the heel of the lower jaw. 
       FIG. 18  is a section view taken along line  18 - 18  of  FIG. 17 . 
       FIG. 19  is a section view from the right side of the tool, taken on line  19 - 19  of  FIG. 3 . 
       FIG. 20  is a view similar to a portion of  FIG. 19 , showing a tool bit aligned with the tool bit drive socket portion of the upper handle of the tool. 
       FIG. 21  is a view of the tool taken along line  21 - 21  of  FIG. 20 , showing the adjustment block for the locking pliers, and showing the interconnection of the strut assembly with the upper handle. 
       FIG. 22  is a perspective exploded view of a portion of the lower handle of the tool and the blade latch lever. 
       FIG. 23  is a section view taken in the same direction as  FIG. 19 , showing portions of the handles, with a folding tool blade latched in an extended position. 
       FIG. 24  is a view similar to  FIG. 23 , showing the blade latch lever moved to a position releasing the tool blade to be moved toward a folded position. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Folding Jaws: 
   Referring now to drawings which form a part of the disclosure herein, in a preferred embodiment of the invention a folding multipurpose tool  30  shown in  FIG. 1  has an upper handle  32 , which may also be referred to as a first body member, and a lower handle  34 , which may also be referred to as an operating lever. A pair of jaws such as an upper pliers jaw  36  and a lower pliers jaw  38  are attached to the handles  32  and  34 . In a preferred embodiment of the multipurpose tool  30 , the handles  32  and  34  have the general shape of channels facing toward each other, and may be of sheet metal such as fine-blanked stainless steel about 0.05 inch thick, for example, while the jaws  36  and  38  may be investment castings, suitably finished. 
   An over-center jaw-locking mechanism is included in the tool, and can be adjusted using an adjustment knob  40  located at the rear end  45  of the upper handle  32  to permit the jaws  36  and  38  to be locked while gripping objects of various sizes. Various folding tool blades are normally stored within the lower handle  34  and can be rotated about an axis defined by a pivot shaft  42  extending transversely at the rear end  44  of the lower handle  34 . The tool blades are kept either in a folded position or an extended position by a latch mechanism including a latch lever  46 . The latch lever  46  may be metal injection molded and is carried on a latch lever pivot pin  48  extending transversely through bores in the sides of the lower handle  34 . 
   The multipurpose folding tool  30  can be folded into a compact folded configuration, shown in  FIGS. 2 ,  3 ,  4  and  5 , after disengaging the lower handle  34  from the lower jaw  38 . Both the upper jaw  36  and the lower jaw  38  are carried on the upper handle  32  and can be rotated with respect to it, from the positions shown in  FIG. 1  to the positions shown in  FIG. 2 , about a main jaw pivot axis  50  defined by a jaw pivot shaft  52  extending transversely through the sides of the upper handle  32 , near a front end  53  of the upper handle  32 . While the jaw pivot shaft  52  may be a rivet, it may also be in the form of a solid or tubular bolt and nut engaged by mating threads. The large ends of the jaw pivot shaft help prevent side play and misalignment of the jaws. 
   It will be appreciated that a different arrangement might be used instead to allow the lower jaw  38  to pivot with respect to the upper jaw  36  about an axis not necessarily coincident with the pivot axis  50 , if desired. 
   When the multipurpose tool  30  is in the folded configuration as shown in  FIGS. 2-5 , a heel portion  54  of the lower jaw  38  extends outward through an aperture  56  in the outer side, or back  58  of the upper handle  32 . Similarly, a portion of the upper jaw  36  extends outward through an aperture  60  in the outer side, or back  62  of the lower handle  34 . 
   When the folding multipurpose tool  30  is in the compact, folded configuration shown in  FIGS. 2-5 , the front end  53  of the upper handle is aligned with the front end  64  of the lower handle  34 , and the upper and lower handles  32  and  34  lie alongside each other with an inner side or margin  66  of the upper handle  32  lying closely alongside and facing toward an inner side or margin  68  of the lower handle  34 . An arcuate projecting portion  70  of each side  71  of the channel of the upper handle  32 , adjacent the jaw pivot axis  50 , fits closely within a corresponding hollow  72  in each opposite side  73  of the channel of the lower handle  34 . 
   The locking pliers jaws  36  and  38  are unfolded from the folded configuration shown in  FIGS. 2-5  and placed into the operative configuration shown in  FIG. 1  by the steps shown in  FIGS. 6-9 . First the lower handle  34  is moved downwardly and rearwardly away from the upper handle  32  as shown in  FIG. 6 . A strut assembly  74  interconnects the upper and lower handles  32  and  34 , with a pin  76  engaged in a slot  78  in each side of the upper handle  32  connecting the rear end  80  of the strut assembly  74  with the upper handle  32 . The front end  82  of the strut assembly  74  is interconnected with the front end  64  of the lower handle  34  as will be explained in greater detail below. 
   With the lower handle  34  in the position shown in  FIG. 6  the jaws  36  and  38  can be rotated outward about the main jaw pivot axis  50  to the position shown in  FIG. 7 . As shown in  FIG. 7  the upper jaw  36  in its extended position abuts against the back  58  of the upper handle  32  at its front end  53 . The lower jaw  38  has also been rotated counterclockwise from its position shown in  FIG. 6 , so that the heel  54  of the lower jaw  38  is exposed below the sides  71  of the upper handle  32 . 
   The lower handle  34  is then brought forward, and its front end  64  is mated releasably with the heel  54  of the lower jaw  38  so that the front end  64  of the lower handle  34  can rotate about the heel  54  of the lower jaw  38 . This can be done most easily with the adjustment knob  40  turned in to the position shown in  FIG. 8 , when the front end  64  can be mated with the heel  54  by rotating the lower handle  34  (in a clockwise direction as the tool is shown in  FIG. 8 ) until mating occurs. Once the front end  64  is mated with the heel  54  of the lower jaw  38 , as shown in  FIG. 8A , rotation of the lower handle  34  in a clockwise direction about the heel  54  moves the jaws  36  and  38  toward each other, and toward the position of the jaws shown in  FIG. 9 . 
   Movement of the lower handle  34 , or operating lever, toward the upper handle  32  is limited, maintaining a space between the upper and lower handles  32  and  34  so that they can be manipulated easily to move the jaws  36  and  38  apart from or toward each other as desired. This limitation of the movement of the lower handle  34  is accomplished by a pair of limit stops  84  in the lower handle  34 . Preferably, the limit stops  84  have a form resembling wings, defined by a slit in each side of the lower handle  34  and are bent inward slightly to extend into the space between the sides  73  of the lower handle  34 , as shown in  FIG. 10 . 
   Referring also to  FIGS. 11 and 11A , the strut assembly  74  includes a pair of struts  86 , preferably of sheet steel, that are spaced apart from each other at the rear end  80  of the strut assembly  74 , by a strut block  88  which is, in a preferred embodiment of the invention, generally cylindrical. The pin  76  extends centrally through the strut block  88  and corresponding bores  90  in the struts  86 . Preferably, the pin  76  fits tightly and must be pressed into the bores  90  and thus keeps the struts  86  tightly alongside the strut block  88 . 
   A stop arm  92  of each of the struts  86  is aligned with the limit stops  84  when the jaws  36  and  38  are in the extended and operative positions shown in  FIG. 9 . A shallow V shaped notch  93  is preferably provided in the end of each stop arm  92  to receive a respective one of the limit stops  84 , preventing the lower handle  34  from moving further toward the upper handle  32  beyond the position shown in  FIG. 9 . As will be explained subsequently, this relationship of the limit stops  84  with the stop arms  92  plays an important part in the manner in which the jaws  36  and  38  may be locked when gripping an object. 
   A U shaped portion of the strut  86  beside the stop arm  92  may be beveled to a sharp edge as shown in  FIG. 6  to form a wire-stripper  99 . A wire to be stripped is supported by an adjacent part of the top edge  68  of the lower handle  34 . 
   The upper and lower jaws  36  and  38  are both rotatably mounted on the jaw pivot shaft  52 , as shown in  FIG. 12 . When the upper jaw  36  is in its extended position, as shown in  FIGS. 12 and 13 , it is retained by friction between a small raised cam portion  94  and a retention spring  96  defined by a pair of short parallel slits  98  in the back or outer side  58  of the upper handle  32 . See also  FIG. 3 . As seen in  FIG. 13 , cheeks  100  and  102  are included in the jaws  36  and  38  and may be additional material cast with and protruding laterally from the bases of jaws  36  and  38 , respectively. The cheeks  100  and  102  have mirror-image opposite shapes, and extend laterally outward along the main jaw pivot axis  50  to keep the jaws  36  and  38  centered between the sides  71  of the upper handle  32 . 
   As seen in  FIG. 12 , an upper portion of the upper jaw  36  has a rearwardly directed face  106  that rests against the back  58  of the upper handle  32  at its front end  53 , in an abutment relationship preventing the upper jaw  36  from moving counterclockwise with respect to the upper handle  32 . As a result, when the jaws are in the positions shown in  FIG. 1  and  FIG. 12 , the upper jaw  36  is held stationary with respect to the upper handle  32 , while the lower jaw  38  is free to rotate about the jaw pivot shaft  52 . 
   A short torsion spring  108  has radially-extending ends  110  each engaged with a notch provided in a respective one of the jaws  36  and  38  so that the torsion spring  108  urges the outer ends  112 ,  114  of the jaws  36 ,  38 , respectively, apart from each other with sufficient force to overcome friction between the lower jaw  38  and the adjacent surfaces of the upper handle  32  and the upper jaw  36  and the jaw pivot shaft  52 . The jaws  36 ,  38  thus tend to open apart from each other as limited by the shape of the bases of the jaws at  115  in  FIG. 12 , unless they are squeezed together by action of the handles  32 ,  34 . 
   As the jaws  36  and  38  are rotated about the jaw pivot shaft  52  in moving them from the extended, operational positions to the folded positions depicted in  FIGS. 2-5 , a small inwardly protruding bump  104 , preferably formed by coining the left side  71  of the upper handle  32 , comes to bear against the cheek surface  100  on the upper jaw  36  with sufficient force for friction then to retain both of the jaws  36  and  38  in the position shown in  FIG. 2 , overcoming the opening force of the spring  108 . 
   As seen in  FIG. 12 , the gripping surface of the upper jaw  36  is angled slightly downward with respect to the upper handle  32 , providing a comfortable angle for holding the tool  30  while gripping an object between the jaws  36  and  38 . The jaws  36  and  38  each include a spine portion  116  slightly narrower than the working faces of the jaws  36  and  38 . Preferably, a narrow V shaped groove  118  (see  FIG. 14 ) is provided in the working face of each outer end  112 ,  114 , so that small round objects such as nails can be gripped and pulled; or narrow objects such as the tang of a saber saw blade may be gripped securely and the tool used as a saw. Each of the jaws  36  and  38  includes a sharpened wire cutter section  120  in a preferred version of the tool  30 . In other versions of the tool  30 , not shown, different cutting edges could be provided. 
   Referring next to  FIGS. 15-18 , the front end  64  of the lower handle or operating lever  34  is attached, preferably by a fastener such as a screw  122 , to a thrust block  124  that is part of a jaw-moving linkage including the strut assembly  74 . The thrust block  124  is of metal and may preferably be made by metal injection molding, but could also be made in other ways. 
   A central portion of a detent spring  126  of thin spring material is sandwiched between the thrust block  124  and the inner surface of the back  62  of the lower handle  34 , and a pair of parallel side portions of the detent spring  126  extend therefrom closely along respective sides of the thrust block  124 , as may be seen best in  FIGS. 11 ,  15 A and  18 . The side portions of the detent spring  126  are formed to provide a pair of detent protrusions  128  facing inwardly toward each other and aligned with each other to resiliently grip the heel portion  54  of the lower jaw  38  and fit into detent dimples  130  to interconnect the front end  64  of the lower handle  34  with the heel  54  in an easily releasable manner. 
   Located on the thrust block  124  are a pair of coaxial pivot arms  132 , one on each side of the thrust block  124 , extending laterally to the inner face of the adjacent side  73  of the lower handle  34 , as shown best in  FIG. 18 , to interconnect the thrust block  124  with the strut assembly  74  as a jaw control link in the jaw-moving linkage. 
   The thrust block  124  includes a concave forward surface  134 , and the heel  54  includes a convex rear surface  136 . The two surfaces  134  and  136  are preferably both cylindrical and of nearly the same radius of curvature so that they fit slidingly and concentrically together to permit the thrust block  124  to rotate with respect to the heel  54  about an axis of rotation  138  extending transversely of the tool  30 . 
   When the lower handle  34  is engaged with the heel  54 , the detent spring  126  retains the heel  54  adjacent the thrust block  124  with the surfaces  134  and  136  in mated relationship with one another for relative rotation about the axis  138 . The detent protrusions  128  are preferably located with their centers slightly closer than the axis  138  to the concave surface  134  of the thrust block  124 , so that cam action of the surfaces of the dimples  130  on the detent protrusions  128  will keep the surfaces  134  and  136  snugly together during use of the locking pliers. 
   The detent spring  126  can be flexed by cam action of the dimples  130  to disengage the detent protrusions  128  from the dimples  130  by simply rotating the lower handle  34  counterclockwise from the position shown in  FIG. 9  past the position shown in  FIG. 8A . The front margin  140  of the back  62  will ride upon the heel  54  where it joins the lower jaw  38  at  142 , using it as a fulcrum so that further rotation then forces the detent protrusions  128  to be disengaged from the dimples  130 , allowing the lower handle  34  to separate from the heel  54 . 
   Jaw Adjustment and Locking: 
   The strut assembly  74  is connected with the thrust block  124  as a part of the jaw-moving linkage by engagement of each of the pivot arms  132  in a respective elongated hole  144  in each of the struts  86 , at the front end  82  of the strut assembly  74 . In one method of assembly, the pin  76  is inserted from outside the upper handle  32  through one of the slots  78  into the bores  90  in the struts  86  and through the strut block  88  after the struts  86  have first been placed on opposite sides of the thrust block  124  with the pivot arms  132  engaged in the elongated holes  144 . 
   In an alternative construction (not shown) the strut block  88  could be attached to the struts  86  by a separate fastening, and the pin  76  could be fitted removably or even be made as a spring-loaded pin to permit complete separation of the handles  32 ,  34  from each other. 
   The rear end  80  of the strut assembly  74  is moveable longitudinally along the upper handle  32  of the folding multipurpose tool  30  within the slots  78  in which the opposite ends of the pin  76  are engaged. Movement of the rear end  80  is limited further by the location of the forward end  146  of the adjustment screw  148 , which limits rearward movement of the strut block  88 . 
   As shown in  FIG. 19 , the threads of the adjustment screw  148  are in mated engagement with a threaded bore  152  in an adjustment block  154  mounted in the rear end of the upper handle  32 . The adjustment block  154  may be manufactured by metal injection molding techniques and is retained in the handle  32  by a fastener such as an attachment screw  156  fitted into a boss  155  that protrudes from the block  154  and extends through a corresponding hole in the back  58 . Axial forces are carried from the adjustment block  154  to the upper handle  32  by the boss  155 , the screw  156 , and a pair of ears  158  formed as part of the adjustment block  154  and resting against corresponding vertical surfaces  160  of a cutout provided in each of the sides  71  of the upper handle  32 . 
   The jaw control linkage, then, controls the position of the lower jaw  38  with respect to the upper jaw  36  when the upper jaw  36  is in its extended position and the lower jaw  38  is in its operative position with the front end  64  of the lower handle  34  connected with the heel  54  of the lower jaw  38  by the heel  54  being mated with the thrust block  124 . Movement of the lower handle  34 , to which the thrust block  124  is connected, moves the pivot arms  132  with respect to an imaginary force line  162  extending from near the axis of rotation  138  to a location near the central axis of the pin  76 . The exact places of application of the forces in the jaw moving linkage, it will be understood, are determined principally by the contact between the surface  134  of the thrust block  124  and the surface  136  of the heel  54 , and by the resolution of forces among the end  146  of the adjustment screw  148 , the outer surface of the strut block  88 , and inside surfaces of the handle  32 . With the pivot arms  132  riding in the ends of the elongated holes  144  nearer to the rear end  80  of the strut assembly  74 , as the central axis  164  of the pivot arms  132  approaches the imaginary line  162 , the heel  54  is urged away from the pin  76  by the thrust block  124 , and thus the lower jaw  38  is urged to pivot about the jaw pivot shaft  52  toward the upper jaw  36 . 
   When the handles  32  and  34  are separated and the jaws  36  and  38  are opened apart from each other the central axis  164  is on the side of the imaginary line  162  closer to the lower handle  34 . With the central axis  164  of the pivot arms  132  located on the imaginary line  162 , the distance between the upper and lower jaws  36  and  38  is at the minimum established by the particular position of the forward end  146  of the adjustment screw  148 . As the lower handle  34  is rotated further toward the upper handle  32  about the axis of rotation  138  the central axis  164  moves over-center across the imaginary line  162  a small distance. At that point the stop arms  92  come into contact with the limit stops  84 , as shown in  FIGS. 9 ,  10  and  15 , with only a small relaxation of pressure between the jaws  36  and  38  and an object held between them. Thus, the tool  30  provides over-center locking pliers with jaws that can be folded to a compact configuration. Forces urging the jaws  36  and  38  apart from each other are carried through the jaw control linkage and urge the stop arms  92  toward the limit stops  84 , thus keeping the jaws  36  and  38  locked in such an over-center relationship. To release the grip of the jaws  36  and  38  it is merely necessary to move the handles  32  and  34  apart from each other far enough to move the central axis  164  back over-center toward the lower handle  34 . 
   Movement of the adjustment screw  148  rearward by rotation of the adjustment knob  40  provides for greater spacing between the outer ends  112  and  114  of the jaws  36  and  38 . The adjustment screw also acts as an extension of the upper handle  32  to give greater leverage to be applied to the upper handle  32  as the jaws  36  and  38  are separated further. 
   It will be understood that the forces urging the lower jaw  38  toward the upper jaw  36  are compressive forces carried from the rear end  45  of the upper handle  32  through the adjustment block  154  and adjustment screw  148 , and through the strut assembly  74  from the forward end  146  of the adjustment screw  148 , through the strut block  88 , the pin  76 , the struts  86 , and the rear ends of the elongated holes  144  and the pivot arms  132  into the thrust block  124 , and that these forces are then carried by the thrust block  124  into the heel  54  of the lower jaw  38  through the mutually contacting surfaces  134  and  136 . Because of the geometry between the thrust block  124  and the remainder of the jaw-moving linkage, the attachment of the lower handle  34  to the thrust block  124  need never be subjected to an extremely large amount of force, and the screw  122  therefore need not be large. 
   As shown in  FIG. 19 , when the tool  30  is in the compact folded configuration the pivot arms  132  are located in the front end of the elongated holes  144 . As may be seen in  FIG. 2 , this allows the stop arms  92  to slide into the space defined within the channel between the sides  73  of the lower handle  34 , without engaging the limit stops  84 , and the limit stops  84  fit in the U shaped area of the struts  86  beside the stop arms  92 . Referring again to  FIG. 19 , with the pivot arms  132  in the front ends of the elongated holes  144 , and with the strut assembly  74  moved toward the front end  53  of the upper handle  32  so that the pin  76  moves toward the forward end of the slots  78 , the ends of the upper handle  32  can be aligned with the ends of the lower handle  34 , with the thrust block  124  fitting adjacent the rear face  106  of the upper jaw  36 . The jaws  36  and  38  are located between the struts  86 , which extend closely along the cheeks  100  and  102  at the front end  82  of the strut assembly  74 . 
   Once the jaws  36  and  38  are placed as shown in  FIG. 6 , the just-described alignments occur without any particular effort as the handles  32  and  34  are moved to the configuration shown in  FIG. 2 . Although parts of the design and construction are complex, most of the motions and positioning of the various components which are required when using the tool occur automatically or intuitively to the user. 
   A bump  168 , shown in  FIG. 11 , protrudes outwardly from one of the struts  86  toward the inner surface of the adjacent side  73  of the lower handle  34 , pressing against it with sufficient friction to keep the strut  86  in the folded position within the lower handle  34 , thereby retaining the upper and lower handles  32  and  34  together when the tool  30  is in the compact folded configuration. The bump  168  may be created by coining the left strut  86 . A hole  170  may be provided in the right strut  86  to assist in forming short radius bends in wires, and to provide access after assembly of the tool  30 , to make adjustments to the bump  168 . 
   As may be seen in  FIGS. 19-21 , the adjustment block  154  defines a rectangular stabilizer cavity  172  facing openly toward the interior of the channel defined by the lower handle  34 . A projecting part  174  located in the lower handle  34  extends into the cavity  172 , stabilizing the lower handle  34  both laterally and longitudinally with respect to the adjacent upper handle  32  when the tool  30  is in its compact folded configuration. It will be understood that the stabilizer cavity  172  need not have any specific shape, but that the cavity  172  and the projecting part  114  preferably should correspond generally in size and shape. 
   The projecting part  174  may be, for example, a portion of the base or tang  210  of one of the folding tool blades carried on the blade pivot shaft  42 , and preferably is part of the tang  210  of the Phillips head screw driver  176 , as may be seen in  FIG. 1 . Because of its shape the Phillips head screwdriver  176  may be made by metal injection molding, although other methods of manufacture may also be used. 
   Referring still to  FIG. 19 , it will also be seen that a retention spring  178  is mounted within the upper handle  32 , with its base portion located between the adjustment block  154  and the inner surface of the back  58 , where the retention spring  178  is held in place by the attachment screw  156 . An outer end of the retention spring  178  extends inwardly through an opening  180  defined in the adjustment block  154 , and presses against the surface of the adjustment screw  148 , to prevent the adjustment screw  148  from being moved unintentionally and thus inadvertently being removed from its threaded bore  152  when the folded tool  30  is not being used, and to prevent changing an adjustment of the jaws when none is intended, during use of the tool  30 . 
   The portion of the adjustment block  154  nearest the rear end  45  of the upper handle  32  defines a tool bit driving socket, for example a hexagonal socket  182  preferably, but not necessarily, at least slightly larger in its minimum dimensions than the outer diameter of the threads  150  of the adjustment screw  148 , although threads  150  could also be formed to some extent in the walls of the tool bit driving socket. The tool bit driving socket is of an appropriate size to receive a shank of a tool bit such as the hexagonal shank  184  shown aligned with the open end of the socket  182  in  FIG. 20 . The outer end of the retention spring  178  thus extends in through a wall of the socket  182  to press against a tool bit shank located in the socket  182 . The spring  178  is preferably located in such a position with respect to the length of the socket  182  that its outer end can extend slightly into a detent groove  186  defined in the shank  184  to hold the tool shank  184  in the socket  182 . 
   It will be appreciated that engagement of the projecting part  174  in the hole  172  is useful in keeping the upper and lower handles  32  and  34  aligned with each other when the tool  30  is used to rotate a tool bit whose shank  184  is engaged in the socket  182 . 
   Latch Mechanism for Folding Tool Blades: 
   Referring to  FIGS. 22-24 , the previously mentioned latch mechanism will be explained in greater detail. In  FIG. 22 , it will be seen that an aperture  188  is defined by the outer side or back  62  of the lower handle  34  adjacent its rear end  44 , and a long narrow spring  190  remains as a portion of the back  62 , extending axially with respect to the lower handle  34  into the open area of the aperture  188  from a remaining transverse band  191  of the material of the back  62 . The latch lever  46  has a pair of ears  192  located closely alongside the inner surfaces of the sides  73  of the lower handle  34 , and thus in positions straddling the spring  190 . The ears  192  define collinear bores to receive the pivot pin  48 , which extends transversely of the lower handle  34  through the collinear bores in the sides  73  and through the bores in the ears  192 . As may be seen in  FIG. 23 , a protrusion  193  is provided on the rear end of the latch lever  46 , where the protrusion  193  rides against the free end of the spring  190 , deflecting it slightly inward with respect to the lower handle  34  when a tool blade, such as the combined file and screwdriver blade  194 , has been pivoted about the blade shaft  42  to an extended position. 
   In addition to the file blade  194  with its straight screwdriver tip, there may be additional tool blades, such as a narrow straight bladed screwdriver  196  combined with a bottle cap remover, a medium width screwdriver  198 , and a knife blade  200 , as well as the previously mentioned Phillips head screwdriver  176 . So that adjacent blades do not move with each other, these tool blades are preferably separated from one another along the blade pivot shaft  42  by thin spacers (not shown) that rest on the interior of the handle  34  and thus cannot rotate about the shaft  42 . Between the file blade  194  and the combined small screwdriver and bottle cap remover  196 , a lanyard eyelet  201  of thin sheet metal is provided. It will be appreciated that the lanyard eyelet  201  need not be in that location, but the screwdriver  196 , because of its small size, may be of reduced thickness to provide space conveniently for the lanyard eyelet  201  alongside the small screwdriver  196 . The lanyard eyelet  201  is preferably of a shape which is symmetrical about an imaginary line  203  shown in  FIG. 23 , in order to simplify assembly of the tool  30 , and can be rotated into the handle if not being used. 
   The small screwdriver  196  and medium screwdriver  198  are preferably flat on their sides facing apart from each other, while the opposite faces, adjacent the centrally-located Phillips head screwdriver  176 , are tapered to the desired thickness of the edge of each of the screwdrivers  196  and  198 , leaving room for the cruciform tip of the Phillips head screwdriver  176  between them. 
   Each of the folding tool blades  176 ,  194 ,  196 ,  198 , and  200  has a tang or base portion  210  defining a respective bore  214  through which the blade pivot shaft  42  passes with a close fit permitting each of the tool blades to rotate smoothly about the blade pivot shaft  42 . The base or tang  210  of each of the tool blades also includes a respective notch  202  to receive the catch body  204  located at one end of a catch carrier arm  206  portion of the latch lever  46 . On the opposite side of a pivot axis defined by the ears  192  and pivot pin  48  is a rear end or latch release push button portion  208  of the latch lever  46 , whose outer side preferably is provided with a non-slip surface such as the parallel grooves illustrated in  FIG. 22 . 
   Approximately opposite the notch  202  on the tang or base  210  of each of the tool blades  176 ,  194 ,  196 ,  198  and  200 , separated from the notch  202  by an angle of about  160   1801 , is an arcuate surface  216 , adjacent which is a cam lobe  218 . Between the cam lobe  218  and the notch  202  is a substantially arcuate margin surface  220  of a radius greater than that of the arcuate surface  216  preferably centered on the shaft  42 . A projecting face or kick  217  on each tool blade is provided to prevent each tool blade from moving too deeply into the channel of the lower handle  34 . 
   Within the notch  202  is an arcuate bottom surface  222 , adjoining an anti-folding face  224  extending inwardly from the surface  220  to define one side of the notch  202 . Opposite the anti-folding face  224 , and thus defining the opposite side of the notch  202 , is an abutment surface  226 . A radial dimension  228 , between the blade pivot shaft  42  and the arcuate surface  216 , and a radial dimension  230 , between the blade pivot shaft  42  and the arcuate bottom surface  222  of the notch  202 , are preferably equal to each other and at least as great as a minimum required for the tang  210  to be of ample strength. The arcuate surfaces  216  and  222  are preferably circular and concentric with the tool pivot shaft  42  to provide the greatest radial dimensions  228  and  230  for practicality, but other slightly different curvatures or locations of those surfaces could also be used in accordance with this invention. 
   As seen in  FIG. 24 , the catch body  204  includes a rear face  232 , a bottom face including an arcuate surface  234 , and a front face  236 , which correspond respectively with the anti-folding surface  224 , the arcuate bottom surface  222 , and the abutment surface  226  of the notch  202 . 
   The push button end  208  of the latch lever  46  overhangs the back  62  of the handle  34  beyond the aperture  188 , as shown in  FIGS. 23 and 24 , so that the margin  238  of the aperture  188  performs as a positive stop to limit the range of motion of the push button or latch release portion  208  of the latch lever  46 , as shown in  FIG. 24 . Ordinarily, the spring  190 , resting against the protrusion  193 , urges the latch lever  46  to rotate toward the position shown in  FIG. 23 , in which the catch body  204  is mated fully within the notch  202  of any of the tool blades which is in its extended position, ready for use. 
   When the rear or push button portion  208  of the catch lever  46  is depressed fully to the position shown in  FIG. 24 , the rear face  232  is disengaged from the anti-folding face  224  of the notch  202 , freeing an extended tool blade such as the file and screwdriver  194  to move, clockwise as shown in  FIG. 24 , toward a folded position for storage within the handle  34 . Nevertheless, a part of the front face  236 , because of its greater length in a generally radial direction, remains opposite the abutment surface  226  within the notch  202 , preventing an extended tool blade from moving too far around the blade pivot shaft  42  in the direction away from the stowed, folded position in the lower handle  34 . Thus, regardless of the push button end  208  of the latch lever  46  having been depressed, a selected blade will not collapse in the direction of opening the blade beyond its normal extended position. 
   When the upper handle  32  is separated from the lower handle  34 , if the push button end  208  of the latch lever  46  is depressed to its limited position as shown in  FIG. 24 , any tool blade which has been extended can then be rotated back into its storage position in the lower handle  34 , with the arcuate surface  234  of the catch body  204  riding along the outer arcuate surface  220  of the tang or tangs  210 . When the catch body  204  is thus riding along the arcuate surface  220  of one of the blades, others of the blades are also free to move between a folded position within the handle  34  and an extended position. Preferably, a small amount of side pressure is provided to keep the folding tool blades in their folded positions. Additionally, if one of the folding tool blades  176 ,  194 ,  196 ,  198  or  200  is moved outwardly from its folded position within the lower handle  34  the cam  218  will raise the catch body  204  as such a blade is moved outward, releasing a blade that previously was in its extended position to be rotated about the blade pivot shaft  42 . 
   When all of the tool blades  176 ,  194 ,  196 ,  198  and  200  or such blades as are located in the lower handle  34  in place of those specific blades, are folded, the spring  190 , acting against the protrusion  193 , keeps the folded tool blades in their respective folded positions by urging the catch body  204  against the arcuate surfaces  216 , and against the cam  218  of the tang  210  of any blade beginning to rotate away from the folded position. 
   The presence of the arcuate surface  234 , corresponding with the shape of the arcuate surfaces  216  and  222 , provides room between the catch body  204  and the blade pivot shaft  42  for ample material for strength of the tangs  210 . This shape also leaves room for an anti-folding surface  224  of ample size, and provides for the front face  236  to extend radially further into the handle  34  than the rear face  232 , so that the rear face  232  can be disengaged from the anti-folding face  224  without disengaging the front face  236  from the abutment  226  in the limited space available in a compact folding tool. 
   It will be noted that the Phillips screwdriver  176 , in its folded position, is inclined upward toward the margins of the sides  73  of the lower handle  34  so that its outer end is available to be engaged to lift the Phillips screwdriver  176  from its folded position. Accordingly, a notch  202  in the tang  210  of the Phillips screwdriver is aligned at a slightly different angle with respect to the kick  217  in order to have the shank of the Phillips screwdriver  176  aligned properly with the lower handle  34  in its extended position. 
   The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.