Patent Publication Number: US-9889543-B2

Title: Clamping tool

Description:
This application is a continuation of international application number PCT/EP2014/058683 filed on Apr. 29, 2014 and claims the benefit of German application No. 10 2013 104 413.1 filed on Apr. 30, 2013, which are incorporated herein by reference in their entirety and for all purposes. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a clamping tool, comprising a base, a clamping arm articulated to the base for pivotal movement about a first pivot axis, a handle articulated to the clamping arm or the base for pivotal movement about a second pivot axis, a bridge element articulated to the handle or the clamping arm for pivotal movement about a third pivot axis, a first wedge element having a first wedge surface, said first wedge element being linearly guided on a guide, and a second wedge element having a second wedge surface facing towards the first wedge surface, said second wedge element being adapted to the first wedge element and being linearly guided, wherein in a first positional range of the handle, the first wedge surface and the second wedge surface are spaced apart from one another and wherein in a second positional range of the handle, the second wedge surface is supported on the first wedge surface and a displacement of the first wedge element drives a displacement of the second wedge element. 
     Toggle clamping tools are used for example to clamp workpieces in place on a machine table. The displacement capability of the first wedge element allows adjustment to accommodate different heights of workpieces to be clamped within a certain range. 
     U.S. Pat. No. 4,407,493 discloses a toggle clamp which is self-adjusting (“self-adjusting toggle clamp”). 
     Further toggle clamps are known from US 2010/0148414 A1 or WO 2010/045504 A1. 
     U.S. Pat. No. 2,350,034 discloses a toggle clamp having a base and an L-shaped clamping arm made of a U-shaped strap having its free ends pivotally connected to the base. The connection is at a point where a pivot bearing passes laterally through the strap ends. Furthermore, there is provided a clamping element which is located at the other end of the clamping arm. A handle has one of its ends pivotally connected to a point located in the bend of the L of the clamping arm. A link has one end pivotally connected to the base and the other end pivotally connected to the handle at a point between the pivotal connection of the handle with the clamping arm and the pivotal connection between the link and the base. When the corresponding parts are in a clamping position, the pivotal connections between one end of the link and the base, the handle with the clamping arm, and the handle with the other end of the link are aligned in one line. The pivotal connection between the handle and the other end of the link is intermediate the other of the pivotal connections. The base has provided thereon means for limiting the movement of the link and the clamping arm. 
     Further clamping tools are disclosed in U.S. Pat. Nos. 3,116,656, 2,531,285, 3,600,986 and 2,751,801. 
     SUMMARY OF THE INVENTION 
     In accordance with an exemplary embodiment of the invention, there is provided a clamping tool which affords a wide range of variation with simplicity of construction. 
     In accordance with an exemplary embodiment of the invention, the bridge element is connected to the first wedge element and is articulated to the first wedge element for pivotal movement about a fourth pivot axis. 
     In the solution in accordance with the invention, the bridge element is permanently connected to the first wedge element by a joint connection for the articulating action. The number of components can thereby be kept low, and therefore the corresponding clamping tool is easy to manufacture. There results a wide range of variation for the clampability of workpieces in terms of workpiece height above a support upon which the clamping tool is set. This affords a simple way of adjusting a clamping force. 
     The clamping tool constructed in accordance with the invention, when configured as a toggle clamp, can be used for example as a machine clamp or as pliers, such as locking pliers. 
     In particular, the bridge element is of rigid configuration and is in particular formed in a one-piece configuration. This makes the clamping tool simple to manufacture. 
     For the same reason, it is advantageous for the bridge element to be of rigid configuration between a joint for articulation to the handle or to the clamping arm and a joint for articulation to the first wedge element. The bridge element then merely represents a fixed bridge element. 
     Advantageously, the first pivot axis, the second pivot axis, the third pivot axis and the fourth pivot axis are oriented parallel to one another. A clamping tool can thereby be realized in a simple manner. 
     It is particularly advantageous for an adjustment device to be provided which acts on the second wedge element and which provides a capability of adjusting a position of the second wedge element in which the first wedge element acts on the second wedge element for driving it. The adjustment device provides a capability of adjusting at what pivotal position of the handle the first wedge element starts driving the second wedge element. The locking force of the clamping tool for a workpiece is thereby capable of being adjusted. 
     It is particularly advantageous for the adjustment device to be arranged on the bridge element and, in particular, to be held on the bridge element. The bridge element then has the same pivot point as the bridge element. This results in a simple construction of the clamping tool. The adjustment device can be easily accessed by use of a tool, such as a screwdriver, or without the use of tools because there is enough space available for this action. It is easily implemented that a clamping force is capable of being adjusted in a defined manner over a large angular range for the clamping arm relative to a support, and in particular over the entire angular range. Once adjusted, the clamping force is at least approximately the same for different workpiece heights. The clamping tool is thereby easy to use. 
     In an exemplary embodiment, the adjustment device comprises an operative element located on the bridge element for pivotal movement about a fifth pivot axis. It is then possible for the locking force to be adjusted by a relative angular position of the operative element relative to the bridge element. 
     In particular, the fifth pivot axis is parallel to the fourth pivot axis. This makes for a simple construction. 
     In an advantageous embodiment, the operative element has located thereon an adjustment element by which an angular position of the operative element relative to the bridge element is capable of being fixably adjusted. In particular, the adjustment element is a spacer element which fixes a distance to the bridge element at or near an end of the operative element, thereby fixing the angular position of the operative element relative to the bridge element. 
     In an embodiment that is advantageous in terms of manufacturability, the adjustment element is a screw which is guided in a thread on the operative element and which is in particular supported at one end thereof on the bridge element. This gives simplicity of construction. Threadedly guiding the screw provides a simple way of fixably adjusting the relative position of the operative element relative to the bridge element. 
     Provision may be made for the operative element to be supported on the first wedge element in at least a portion of a range of pivotal motion of the operative element. This results in increased stability. 
     It is advantageous for the operative element to be of rounded configuration in an area in which it is capable of acting on the second wedge element. The rounding is defined. This provides an effective way of fixing the starting position of the second wedge element within a predetermined pivoting range and hence, in turn, of fixing the position at which the first wedge element can start driving the second wedge element. This in turn fixes the locking force. With appropriate configuration, an angle-independent clamping force can be at least approximately adjusted. 
     It is advantageous for a spring device to be provided which acts on the second wedge element, wherein a spring force of the spring device tends to urge the second wedge element in a direction towards the bridge element. The spring device then provides for the second wedge element to be able to be in contact against a contact surface of an adjustment device when the first wedge element does not yet contact the second wedge element. 
     In an embodiment, the guide is arranged on the base. This makes for a simple construction. 
     In an embodiment, the base has an underside which faces away from the clamping arm and the guide is spaced at a height distance from the underside of the base. An interspace is thereby formed between a plane on which the underside lies and the guide. This can be utilized, for example, to arrange the guide in a handle element which is capable of being grasped by an operator. For example, when the base is fixed via its underside to an application, then there exists an interspace between the application and the guide and hence the handle element. An operator can reach through this interspace and, for example, grasp the handle and the handle element with one hand. 
     In an exemplary embodiment, the clamping tool is capable of being fixed to an application via the underside of the base. This enables easy fixability. 
     It is particularly advantageous for the base to have a handle element arranged thereon. This allows an operator to grasp the handle element and the handle with one hand and, for example, clamp a workpiece by moving the handle in a direction towards the handle element. For example, the workpiece can then be clamped between the clamping arm and a support or between the clamping arm (first clamping arm) and a second clamping arm which is arranged on the base. 
     In an embodiment that is simple in structure, the handle element is rigidly connected to the base. 
     It is advantageous for the application if, in a starting position of the clamping tool, the handle and the handle element are oriented at least approximately parallel to one another. The starting position is in particular a clamping position. This provides an easy way of realizing for example a toggle clamp in the form of a horizontal clamp or in the form of locking pliers, wherein a workpiece is capable of being clamped by moving the handle in a direction towards the handle element. 
     In particular, it is advantageous for the guide to be arranged on the handle element. This makes for a compact construction of the clamping tool combined with ease of use. 
     In particular, the first wedge element and the second wedge element are then arranged on the handle element and capable of being linearly guided thereon. This results in a simple and compact construction with many capabilities of use. 
     It is further advantageous for the handle element of the base and the handle to be arranged oppositely to each other and to be capable of being grasped in common by the hand of an operator. This results in ease of use and, in particular, enables one-hand operation. 
     In an exemplary embodiment of a clamping tool in the form of a toggle clamp, the clamping arm is a first clamping arm and the base has arranged thereon a second clamping arm, wherein a workpiece is capable of being clamped between the first clamping arm and the second clamping arm. A toggle clamping tool that provides adjustable clamping force is thereby realized. Such a clamping tool may be used as locking pliers, for example. 
     In particular, the second clamping arm is then fixidly connected to the base. In this manner, corresponding pliers can be realized which are simple in structure. 
     In particular, the clamping tool, which is a toggle clamp, is then configured as pliers and/or locking pliers. 
     When the clamping tool is configured as pliers, it is advantageous for the clamping arm and/or a further clamping arm to have a first region, said first region having located thereon an angled second region, wherein the second region has arranged thereon a contact element for a workpiece. It is thereby possible to achieve a high clamping force for clamping a tool. 
     It is advantageous for the contact element to be pivotally or rotatably located on the second region. This allows for an alignment to be achieved in order, for example, to compensate for irregularities or to enable clamping of workpieces having non-parallel opposing surfaces. 
     In particular, the second region is oriented relative to the first region in an angular range between 70° and 110° and, preferably, the second region is oriented to the first region at at least approximately right angles. Pliers, such as locking pliers, can thereby be implemented in an advantageous manner. 
     For the same reason it is advantageous if, where a first clamping arm and a second clamping arm are present, the second region of the first clamping arm and the second region of the second clamping arm are aligned at least approximately in line with each other when the first clamping arm is in a starting position. This results in an effective clampability of a workpiece between corresponding contact elements of the first clamping arm and the second clamping arm. 
     A clamping tool constructed in accordance with the invention can be configured as a horizontal clamp in which clamping of a workpiece by the clamping arm is capable of being effected by pivoting the handle in a direction towards the base. 
     In particular, the clamping arm is then articulated to the base, the handle is articulated to the clamping arm and the bridge element is articulated to the handle. 
     It is advantageous for the bridge element to be oriented at least approximately parallel to the clamping arm when at a toggle lever dead centre. A horizontal clamp can thereby be implemented in a simple manner. 
     The following description of preferred embodiments serves in conjunction with the drawings to explain the invention in greater detail. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 to 6  are schematic representations of a first exemplary embodiment of a clamping tool constructed in accordance with the invention and configured in the form of a toggle clamp, wherein; 
         FIG. 1  is a schematic sectional view in a first position of the handle; 
         FIG. 2  is an enlarged view of the detail of  FIG. 1 ; 
         FIG. 3  is the toggle clamp of  FIG. 1 , shown in a second position of the handle; 
         FIG. 4  is the detail of  FIG. 3  on an enlarged scale; 
         FIG. 5  shows a locking position of the handle; 
         FIG. 6  is an enlarged view of the detail of  FIG. 5 ; 
         FIGS. 7 to 12  illustrate a second exemplary embodiment of a clamping tool constructed in accordance with the invention and configured in the form of a toggle clamp, wherein 
         FIG. 7  shows the toggle clamp in a first position; 
         FIG. 8  shows the detail of the marked area in  FIG. 7  to an enlarged scale; 
         FIG. 9  is the toggle clamp of  FIG. 7 , shown in a second position of the handle; 
         FIG. 10  is the detail of the marked area in  FIG. 9  on an enlarged scale; 
         FIG. 11  shows a locking position of the handle; 
         FIG. 12  is an enlarged view of the detail of the marked area in  FIG. 11 ; 
         FIG. 13  is the toggle clamp of  FIG. 9  being used on a larger-sized workpiece; 
         FIGS. 14 to 19  illustrate a third exemplary embodiment of a clamping tool constructed in accordance with the invention and configured in the form of a toggle clamp, wherein 
         FIG. 14  is the toggle clamp in a first position of a handle; 
         FIG. 15  shows the detail of the marked area in  FIG. 14  to an enlarged scale; 
         FIG. 16  shows a second position of the handle of the toggle clamp of  FIG. 14 ; 
         FIG. 17  is the detail of the marked area in  FIG. 16  on an enlarged scale; 
         FIG. 18  shows a locking position of the handle; 
         FIG. 19  is a view of the detail of the marked area in  FIG. 18  to an enlarged scale; and 
         FIG. 20  is the toggle clamp of  FIG. 14  being used on a larger-sized workpiece; 
         FIGS. 21, 22  illustrate a fourth exemplary embodiment of a clamping tool constructed in accordance with the invention and configured in the form of a toggle clamp, wherein 
         FIG. 21( a )  is a side view of the toggle clamp; 
         FIG. 21( b )  is a top view of a mounting plate for the toggle clamp of  FIG. 21( a ) ; 
         FIG. 22  is a partial section view of the toggle clamp of  FIG. 21( a ) ; 
         FIGS. 23, 24  illustrate a fifth exemplary embodiment of a clamping tool constructed in accordance with the invention and configured in the form of locking pliers, wherein  FIG. 23  is a side view of the locking pliers; and 
         FIG. 24  is a partial sectional view of the locking pliers of  FIG. 23 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A first exemplary embodiment of a clamping tool constructed in accordance with the invention is a toggle clamp, shown in  FIGS. 1 to 8  and indicated therein by  10 , and comprises a base  12 . By way of the base  12 , the toggle clamp  10  is capable of being affixed to a support  14 . The support  14  is for example a machine table. The base  12  is capable of being secured to the support  14  by, for example, screws. A workpiece  15  is to be clamped to the support  14  by use of the toggle clamp  10 . 
     A clamping arm  20  is articulated to the base  12  via a first joint  16  which defines a first pivot axis  18 . The first pivot axis is oriented perpendicularly to the drawing plane in  FIG. 1 . In particular, it is oriented parallel to the support  14 . 
     The clamping arm  20  is of angled configuration having a first region  22  and a region  24  oriented transversely to the first region  22 . The first joint  16  is positioned in the vicinity of an end of the first region  22 . 
     Located at the second region  24 , in the vicinity of an end  26  thereof, is a contact element  28  which is in particular configured as a pressure piece. The contact element  28  is supported on a holding ball  30 . The contact element  28  has a contact surface  32  for the workpiece  15 . The contact element  28  further has a receptacle  32  which is adapted to the holding ball  30 . By the holding ball-and-receptacle connection of the contact element  28 , the pivotal position of the contact element  28  relative to the clamping arm  20  is variable. 
     The holding ball  30  is fixed to the second region  24  of the clamping arm  20  via a holding pin  34 . 
     In an embodiment, a distance of the contact element  28  from the clamping arm  20  is capable of being fixably adjusted. To this end, for example, the holding pin  34  is configured, in particular in a portion thereof, as a threaded pin which is guided on a thread of the clamping arm  20 . 
     A handle  40  is articulated to the clamping arm  20  via a second hinge  36  which defines a second pivot axis  38 . The second joint  36  is arranged at the first region  22  in the vicinity of an end facing away from the end which has the first joint  16  positioned in its vicinity. In a state in which the base  12  of the toggle clamp  10  is set on the support, the second joint  36  has a distance from the support  14  that is greater than that of the first joint  16 . 
     The handle  40  is of angled configuration having a first region  42  and a second region  44 . The first region  42  and the second region  44  have a finite angle  46  therebetween in the range between, for example, 120° and 150°. 
     Arranged on the handle  40 , at an end region thereof, is a grip element  48  which is made of, for example, a plastics material. The grip element  48  has a contact region  52  for contact with a user&#39;s hand. 
     The second pivot axis  38  is parallel to the first pivot axis  18 . 
     The handle  40  has arranged thereon a third joint  54  which defines a third pivot axis  56 . The third joint  54  is spaced apart from the first joint  16  and the second joint  36 . The third pivot axis  56  is parallel to the first pivot axis  18 . A distance of the third joint  54  from the support  14  depends on a pivotal position of the handle  40 . A bridge element  57  is articulated to the handle  40  via the third joint  54 . In particular, the third joint  54  is located at the second region  44  of the handle in the vicinity of the transition from the first region  42  to the second region  44 . 
     Formed on the base  12  is a guide  58  for a first wedge element  60 . In particular, the first wedge element  60  is guided for linear slidable displacement in the guide  58  on the base  12 . A direction of displacement  62  thereof is parallel to a guide surface  64  of the base  12 . In particular, the guide surface  64  is of planar configuration. Preferably, the guide surface  64  is oriented parallel to the support  14  when the base  12  is set on the support  14 . The distance of the first wedge element  60  from the support is the same independent of the position the first wedge element  60  assumes on the guide  58 . 
     The first wedge element  60  has an underside  66  with which the first wedge element  60  is set on the guide surface  64 . The underside  66  is oriented parallel to the guide surface  64 . 
     The first wedge element  60  further comprises a first wedge surface  68  which is oriented at an acute angle with respect to the underside  66 , said acute angle being in the range between 10° and 20°, for example. 
     The bridge element  57  is articulated via a fourth joint  70  to the first wedge element  60  and is permanently connected thereto. The fourth joint  70  defines a fourth pivot axis  72  which is parallel to the first pivot axis  18 . The articulation of the bridge element  57  to the first wedge element  60  is outside of the confines of the first wedge surface  68 . 
     The bridge element  57  is of rigid configuration. In particular, it is of rigid configuration, i.e. not movable in itself, between the third joint  54  and the fourth joint  70 . It is not interrupted by another joint or the like. 
     The first wedge element  60  has a second wedge element  74  associated with it. The second wedge element  74  is also linearly guided on the base  12 , in a direction of displacement  76  that is parallel to the direction of displacement  62 . The second wedge element  74  is arranged above the first wedge element  60 . A guide  78  of the second wedge element  74  on the base  12  is configured such that the height position of the second wedge element  74  relative to the guide surface  64  does not change. This is achieved for example by a lateral guide (not visible in the chosen views of the figures). 
     The second wedge element  74  has a second wedge surface  80  which is adapted to the first wedge surface  68  and is parallel thereto. The second wedge element  74  has, at a position opposite the second wedge surface  80 , an upper side  82  via which the second wedge element  74  is guided, for example slidably guided, on a corresponding wall  84  of the base  12  opposite the guide surface  64 . The upper side  82  is oriented parallel to the underside  66  of the first wedge element  60 . 
     In an exemplary embodiment, the second wedge element  74  is supported on the base  12  via a spring device  86 . In particular, the spring device  86  is supported on a rear wall  88  which is located between the wall  84  and the guide surface  64 . Furthermore, the spring device  86 , which has one or more compression springs, is fixed, or supported, on a side of the second wedge element  74  that faces towards the rear wall  88 . 
     A direction of force  90  of the spring device  86  is directed away from the rear wall  88  and towards the bridge element  57 . In particular, the direction of force  90  is oriented at least approximately parallel to the guide surface  64 . The spring device  86  tends to urge the second wedge element  74  in a direction towards the bridge element  57 . 
     Arranged intermediate the first wedge element  60  and the second wedge element  74  is an intermediate element  75 . This is arranged and configured parallel to the wedge surfaces  68  and  80  and is guided parallel to the guide surface  64  on the base  12 . It is guided on the base  12  in such a manner that it is free to move and “float” in a direction of height relative to the base  12 . The first wedge element  60  acts on the second wedge element  74  via the intermediate element  75 . The intermediate element  75  absorbs transverse forces and transfers these to the base  12 . Transverse movement capability of the wedge elements  60  and  74  is thereby precluded. 
     The second wedge element  74  has associated with it an adjustment device  92  which provides the capability of adjusting the position into which the second wedge element  74  is capable of being urged by the spring device  86  in a direction towards the bridge element  57 . A clamping force is adjustable by the adjustment device  92 . 
     The adjustment device  92  comprises an operative element  94 . The operative element  94  has, on a side thereof opposite that side on which the spring device  86  is supported, a contact surface  96  for the second wedge element  74 . In particular, the operative element  94  is of rounded configuration in the area of the contact surface  96  thereof. 
     The operative element  94  is pivotally located on the bridge element  57  via a corresponding holder  98 . To this end, a fifth joint  100  is provided which defines a fifth pivot axis  102 . The fifth pivot axis  102  is parallel to the first pivot axis  18 . 
     The fifth joint  100  divides the operative element  94  in a first region and a second region. The first region has the contact surface  96  formed thereon. The second region has an adjusting element  104  located thereon. The adjusting element  104  is in particular a screw which is guided via an external thread thereof on an internal thread of the operative element  94 . The adjusting element  104  has a region  106  which projects beyond the operative element  94  in a direction towards the bridge element  57 . A length of this region  106  towards the bridge element  57  is adjustable. This is indicated in  FIG. 1  by the double-headed arrow designated by the reference character  108 . The adjusting element  104  is supported via an end of the region  106  thereof on a corresponding outer side of the bridge element  57 . A rotational position of the adjusting element  104  at the operative element  94  determines a pivotal position of the operative element  94  relative to the bridge element  57 . 
     The adjusting element  104  is positioned above the wall  84  so that the adjusting element  104  is capable of having a suitable tool, such as a screwdriver, acting upon it for its adjustment. 
     The toggle clamp  10  is configured as a horizontal clamp. A toggle lever is realized via the joints  16 ,  36 ,  54  and  70 . The workpiece  15  can be clamped to the support  14  by pivoting the handle  40  in a direction towards the base  12 . This direction of motion is indicated in  FIG. 1  by the reference character  110 .  FIG. 1  shows a position of the handle in which the workpiece  15  is not yet clamped. In this position of the handle  40 , the spring device  86  urges the second wedge element  74  against the contact surface  96  of the operative element  94 . The exact locus of the second wedge element  74  relative to the base  12  is adjusted by the position of the adjusting element  104  on the operative element  94 . 
     The toggle clamp  10  is configured and is in particular dimensioned such that in a first positional range of the handle  40  in which no clamping has yet been applied, wherein a position of the handle  40  within the aforesaid first positional range is shown in  FIG. 1 , the first wedge surface  68  is farther from the second wedge surface  80  than the height of the intermediate element  75 . Due to its free support in the direction of height, the intermediate element  75  is on one side thereof in contact against the first wedge surface  68 , and an air gap  112  is formed between an opposite side of the intermediate element  75  and the second wedge surface  80 . 
     In the position illustrated in  FIG. 1 , the bridge element  57  and the support  14  and hence the guide surface  64  are at a certain angle  114  to each other. When the handle  40  is pivoted in the direction  110 , the angle  114  is reduced. This angle reduction also causes the first wedge element  60  to be displaced in a direction of the rear wall  88  by a corresponding pivoting action of the bridge element  57 . Confer  FIGS. 3 and 4 . At a certain position illustrated in  FIGS. 3 and 4 , a position is then reached where the intermediate element  75  contacting the first wedge surface  68  also contacts the second wedge surface  80 , i.e. the air gap has disappeared. 
     The displacement distance travelled by the first wedge element  60  until it reaches the aforesaid position defines the extent of the self-adjustment capability of the toggle clamp  10 . 
     Proceeding from the aforesaid position for a special angle  114 * ( FIGS. 3 and 4 ), when the handle  40  is pivoted further downwardly ( FIGS. 5 and 6 ), then the first wedge element  60  acts upon the second wedge element  74  (with the intermediate element  75  interposed therebetween) and drives a displacement of the second wedge element  74  from the contact surface  96  of the operative element  94  towards the rear wall  88  against the direction of force  90  of the spring device  86 . During this phase of movement the first wedge element  60  is, via its first wedge surface  68  and via the intermediate element  75 , supported on the second wedge element  74  via the latter&#39;s second wedge surface  80 . The movable support of the intermediate element  75  permits co-movement thereof. At a certain angle  114 , a position of dead centre of the toggle clamp  10  is reached. At this dead centre point, in particular, the bridge element  57  is at least approximately parallel to the clamping arm  20  (and in particular to a direction of longitudinal extent  116  of the second region  24  of the clamping arm  20 ), i.e. piercing points of the pivot axes  38 ,  56 ,  72  are on one line with each other. 
     The clamping arm  20  securely presses on the workpiece  15  via the contact element  28  and clamps it against the support. 
       FIGS. 5 and 6  show a position of the handle  40  which is already slightly below the toggle lever dead centre point. 
     In this condition, the workpiece  15  is securely and firmly clamped in place between the contact element  28  on the clamping arm  20  and the support  14 . 
     The clamping force (the toggle lever force) is, in principle, capable of being adjusted by the adjustment device  92 . 
     The bridge element  57 , configured as a rigid element, is directly and permanently connected to the first wedge element  60  and is directly articulated to the latter via the fourth joint  70 . The result is simplicity in construction with a wide range of variation for clamping height (workpiece height). 
     The adjustment device  92  including the adjusting element  104  is arranged on the bridge element  57 . In particular, the operative element  94  is pivotally arranged on the bridge element  57 . This provides a simple way of adjusting the corresponding clamping force (toggle lever force) by the position of the second wedge element  74  in the first positional range of the handle  40 . 
     The adjusting element  104  is easily accessed by use of a standard tool, such as a screwdriver, in order to adjust the corresponding force. 
     The displacement capability of the first wedge element  60  allows compensating for different workpiece heights to a certain extent; a point of support of the clamping arm  20  is variable. The toggle clamp  10  is thereby self-adjusting (“self-adjusting toggle clamp”). 
     A second exemplary embodiment of a clamping tool constructed in accordance with the invention and configured in the form of a toggle clamp, illustrated in  FIGS. 7 to 13  and indicated therein by  120 , comprises a base  122  for fixing to the support  14 . A clamping arm  126  is pivotally articulated to the base  122  via a first joint  124 . The clamping arm  126  has, in principle, the same configuration as the clamping arm  20  described above. The clamping arm  126  also has a contact element  28  located thereon as described above. 
     A handle  130  is pivotally articulated to the base  122  via a second joint  128 . The second joint  128  is spaced at a height distance from the first joint  124 . 
     The handle has located thereon a guide  132  for a first wedge element  134  and a second wedge element  136 . 
     A bridge element  138  is pivotally articulated to the clamping arm  126  via a third joint  140 . The bridge element  138  is pivotally articulated via a fourth joint  142  to the first wedge element  134  and is permanently connected thereto. 
     The first wedge element  134  is capable of being displaced parallel to the handle  130  via the guide  132 . The second wedge element  136  is positioned above the first wedge element  134 . It is urged in a direction towards the bridge element  138  via a spring device  144 . 
     The first joint  124 , the second joint  128 , the third joint  140  and the fourth joint  142  form a toggle lever. 
     Located on the bridge element  138  is an adjustment device which is, in principle, of identical configuration as that of the adjustment device  92 . Therefore, the same reference characters are used as those for the adjustment device  92 . An operative element  94  acts upon the second wedge element  136  via a contact surface  96 . 
     The second wedge element  136  has a recess  146  in the form of, for example, an elongated hole recess. The recess  146  is formed as a through-recess. The through-direction of this recess  146  is perpendicular to the drawing plane of  FIGS. 7 and 8 . The second joint  128  is arranged in the recess  146  and is fixedly positioned with respect to the base  122 . The recess  146  provides displacement capability for the second wedge element  136  on the handle  130 . 
     In order to clamp a workpiece to the support  14 , the handle  130  is pivoted in a direction  148  towards the base. The toggle clamp  120  is also a horizontal clamp. By the aforesaid pivoting action, the bridge element  138  pushes the first wedge element  134  in a direction towards a grip element  150  which is located on the handle  130 . 
     Shown in  FIGS. 7 and 8  is a position of the handle  130  within a first positional range in which a corresponding wedge surface of the first wedge element  134  is spaced apart from the corresponding wedge surface of the second wedge element  136 . The position of the second wedge element  136  on the handle  130  is determined by the adjustment of the adjustment device  92 . The position illustrated in  FIGS. 7 and 8  corresponds to the position which is shown for the toggle clamp  10  in  FIGS. 1 and 2 . 
     The handle  130 , including the guide  132 , and the bridge element  138  are at a certain angle  152  to each other. Pivoting the handle  130  towards the base  122  causes said angle  152  to be reduced. As shown in  FIGS. 9 and 10 , the distance between the first wedge surface of the first wedge element  134  and the second wedge surface of the second wedge element  136  is then reduced and an intermediate element  137  contacts these surfaces. Proceeding from the corresponding angular position  152 *, further reduction of the angle causes displacement, driven by the first wedge element  134 , of the second wedge element  136  in a direction towards the grip element  150  (cf.  FIGS. 11 and 12 ). This movement is realized against the spring force of the spring device  144 . The first wedge element  134  is also displaced away from the contact surface  96  of the adjustment device  92 . 
     A toggle lever dead centre position is at least approximately reached when the angle  152  is 0°, i.e. when the handle  130  and the bridge element  138  are oriented parallel to each other or piercing points of pivot axes of the second joint  128 , the third joint  140  and the fourth joint  142  are on one line with each other. 
       FIGS. 11 and 12  illustrate a position in which the handle  130  is already below dead centre. 
     Again, the adjustment device  92  allows the clamping force (toggle lever force) to be adjusted. 
     In the toggle clamp  120 , the bridge element  138  is also of rigid configuration. It is permanently pivotally connected to the first wedge element  134  and is articulated to the latter. 
       FIG. 13  illustrates an exemplary embodiment corresponding to  FIG. 7  but where a workpiece  154  being clamped has a greater height. 
     A third exemplary embodiment of a clamping tool constructed in accordance with the invention and configured in the form of a toggle clamp, illustrated in  FIGS. 14 to 20  and indicated therein by  160 , comprises a base  162 . A clamping arm  167  is pivotally articulated to the base  162  via a first joint  164  having a first pivot axis  166  (which is perpendicular to the drawing plane in  FIG. 14 ). The clamping arm in turn has located thereon a contact element corresponding to the contact element  28 . A handle  172  is pivotally articulated to the base  162  via a second joint  168  having a second pivot axis  170 . The second pivot axis  170  is parallel to the first pivot axis  166 . The first joint  164  and the second joint  168  are at the same height. 
     The clamping arm  167  has, at a position above the first joint  164 , a bridge element  178  pivotally articulated thereto via a third joint  174  having a third pivot axis  176 . 
     Guided for linear displacement on the handle  172 , on a guide  180 , is a first wedge element  182 . The bridge element  178  is permanently pivotally articulated to the first wedge element  182  via a fourth joint  184  having a fourth pivot axis  186 . 
     The first wedge element  182  has associated with it a second wedge element  188  which is likewise linearly displaceable on the handle  172 . Furthermore, the bridge element  178  has positioned thereon an adjustment device corresponding to the adjustment device  92 . Therefore, the same reference character is used as in the first exemplary embodiment and in the second exemplary embodiment. 
     The toggle clamp  160  is configured as a vertical clamp. Clamping a workpiece to a support is achieved when the handle  172  is pivoted in a direction  190  away from the base  162 . 
     The guide  180  and the bridge element  178  have an angle  192  therebetween. When the handle  172  is pivoted in the direction  190 , the angle  192  is reduced (cf.  FIGS. 14 and 16 ). 
     The second wedge element  188  is supported on a rear wall  196  via a spring device  194 . 
       FIGS. 14 and 15  depict a position within a first positional range of the handle  172  in which an intermediate element  183  on a first wedge surface of the first wedge element  182  does not yet contact the second wedge element  188 . The second wedge element  188  is moved in a direction towards the corresponding operative element  94  of the adjustment device  92  by the spring device  194  and is in contact against the operative element  94 . The adjusted position (pivotal position) of the operative element  94  relative to the bridge element  178  determines this starting position of the second wedge element  188 . 
     Further pivoting of the handle  172  then causes the angle  192  to be reduced. At angle  192 * ( FIGS. 16 and 17 ), the intermediate element  183  is then in contact against the first wedge element  182  and against the second wedge element  188 . Starting at this position, a second positional range is then reached. Further pivoting of the handle  172  causes the first wedge element  182  to act upon the second wedge element  188  and to drive the latter&#39;s displacement against the spring force of the spring device  194  and away from the operative element  94 . 
     A toggle lever dead centre position is reached when the angle  192  is 0°, i.e. when the guide  180  of the handle  172  and the bridge element  178  are at least approximately parallel to each other or piercing points of the pivot axes  170 ,  176  and  186  are on one line with each other. 
       FIG. 20  shows the toggle clamp  160 , with a larger-size workpiece being clamped. 
     In the toggle clamps  10 ,  120 ,  160  constructed in accordance with the invention, a corresponding bridge element  57 ,  138 ,  178  is of rigid configuration and is directly and permanently articulated to the first wedge element  60 ,  134 ,  182 , i.e. a permanent pivotal connection exists between the first wedge element  60 ,  134 ,  182  and the bridge element  57 ,  138 ,  178 . The adjustment device  92  is positioned on the corresponding bridge element  57 ,  138 ,  178  and therefore its pivot point is the same as that of the corresponding bridge element  57 ,  138 ,  178 . 
     This results in a simple construction with a wide range of variation for the clamping action, i.e. with a wide range of variation for the height of workpieces capable of being clamped. 
     The clamping force (toggle lever force) can be adjusted via the adjustment device  92  in a simple manner. In particular, access to the adjusting element  104  can be realized in a simple manner. The clamping force can be at least approximately constantly fixed over a wide angular range/height range of workpieces. 
     A fourth exemplary embodiment of a clamping tool constructed in accordance with the invention, shown in  FIGS. 21, 22  and denoted therein by  200 , is a toggle clamp. Said toggle clamp  200  comprises a base  202 . The base  202  has an underside  204 . Arranged on the underside  204  is a pin  206  having a head  208  located thereon. The head  208  has a diameter greater than that of the pin  206 . The head  208  is spaced apart from the underside  204 . 
     The base  202  and therefore the clamping tool  200  is capable of being fixed to an application via the pin  206  including the head  208  ( FIG. 21( b ) ). For example, a slot  210  is arranged in a corresponding plate  212 , said plate  212  being capable of being affixed to an application, for example a machine table, via corresponding fastening elements  214 , such as screws. 
     The slot  210  has a first region  216  and a second region  218  connected to the first region  216 . The second region  218  is configured such that the head  208  is capable of extending therethrough. The first region  216  is configured such that it forms a barred area for the head  208 . 
     Formed rearwardly of the slot  210  in the plate  212  is a groove  220 . The groove  220  has a width B that is greater than that of the slot  210  in the first region  216  thereof. The barred area for the head  208  is formed by a wall of the groove  220  at the slot  210 . 
     In the second region  218 , the head  208  is capable of being extended into the groove  220 . When the base  202  with the pin  206  and the head  208  is slid into the first region  216 , then the head  208  can come into contact against the barred area, with the pin  206  extended through the slot  210 . Axial fixing can thereby be achieved. 
     For example, the pin  206  including the head  208  is formed as a screw and the base  202  can be clamped to the plate  212 , wherein the head  208  is then in contact against the barred area in the groove  220  and the underside  204  is then in contact against the upper side of the plate  212 . 
     For example, the base  202  is fixed to the plate  212  separately from the application and thereafter the plate  212  is fixed to the application by way of the fastening elements  214 . 
     Fixedly located on the base is a handle element  222 . 
     In an exemplary embodiment, the handle element  222  has a direction of longitudinal extent  224  which is transverse and in particular perpendicular to the underside  204 . 
     Pivotally articulated to the base  202  is a (first) clamping arm  226 . It is pivotable via a corresponding pivot bearing  228  about a first pivot axis  230 . The first pivot axis  230  is oriented transversely and, in particular, perpendicularly to the direction of longitudinal extent  224  of the handle element  222 . In  FIGS. 21( a )  and  22 , the first pivot axis  230  is oriented perpendicularly to the drawing plane. 
     The clamping arm has a middle first region  232  which has located thereon a second region  234  extending towards the one side and a third region  236  extending towards the other side. In particular, the first region  232 , the second region  234  and the third region  236  are connected together in one piece. The clamping arm  226  is articulated to the base  202  via the third region  236 . 
     Arranged on the second region  234  is a contact element  238  for a workpiece. This contact element  238  is located on the second region  234  for pivotal movement about a pivot axis  240 . In particular, the pivot axis  240  is oriented parallel to the first pivot axis  230 , or parallel to the underside  204 . 
     The second region  234  is in an angled relationship relative to the first region  232 . In particular, a corresponding angle is in the range between 70° and 110° and is in particular a right angle. 
     The third region  236  is at an acute angle to the first region  232 . 
     Articulated to the clamping arm  226  is a handle  244 . A corresponding pivot bearing  246  is provided which enables the handle  244  to be capable of pivoting relative to the clamping arm  226  about a second pivot axis  248 . The second pivot axis  248  is parallel to the first pivot axis  230 . 
     Articulated to the handle  244  for pivotal movement about a third pivot axis  250  is a bridge element  252 . 
     Linearly guided on the handle element  222  of the base  202  via a corresponding guide  256  that is arranged on the handle element  222  is a first wedge element  254 . The first wedge element  254  has a first wedge surface  258  that faces towards a second wedge surface  260  of a second wedge element  262 . The second wedge element is also linearly guided on the handle element  222 . The second wedge surface  260  is supported on the first wedge surface  258 . Displacement of the first wedge element  254  causes displacement of the second wedge element  262 . 
     The bridge element  252  is connected to the first wedge element  254  and is articulated thereto for pivotal movement about a fourth pivot axis  266  via a corresponding pivot bearing  264 . The third pivot axis  250  and the fourth pivot axis  266  are parallel to the first pivot axis  230 . 
     The bridge element  252  has associated with it an adjustment device  268  corresponding to the adjustment device  92 . 
     The second wedge element  262  is supported on the handle element  222  via a spring device  270 . 
     The mechanism of the toggle clamp  200  corresponds to the mechanism of the toggle clamp  10  as described above. A workpiece can be clamped between the contact element  238  and a corresponding support (which then has the base  202  fixed thereto). The clamping force (the toggle lever force) can be adjusted via the adjustment device  268 . 
     In the toggle clamp  200 , provision is made for a handle element  222  which is spaced from the underside  204  of the base. The handle  244  and the stationary handle element  222  can be grasped together by one hand of the operator. By pressing the handle  244  downwardly in a direction towards the handle element  222 , the contact element  238  is moved in a direction towards the support in order to clamp a workpiece. The toggle clamp  200  is then a horizontal clamp. 
     By the spacing of the handle element  222  from the underside  204 , an operator can reach through between a support, which has the base  202  fixed thereto, and the handle element  222  and thus grasp the handle element  222  along with the handle  244 . 
     Otherwise, the toggle clamp  200  works like the toggle clamp  10 . 
     A fifth exemplary embodiment of a clamping tool constructed in accordance with the invention, shown in  FIGS. 23 and 24  and indicated therein by  300 , is a toggle clamp in the form of pliers or locking pliers. The locking pliers  300  are of similar configuration as the clamping tool  200 . Like reference characters are used for like elements. 
     The locking pliers  300  comprise a base  302  on which is located the handle element  222  including the corresponding mechanism. Articulated to the base  302  is, correspondingly, the first clamping arm  226  together with its contact element  238 . Pivotally located on the clamping arm  226  is the handle  244 , as described above. 
     The mechanism for providing the toggle lever force and for adjusting the clamping force (toggle lever force) is the same as described above. 
     Located on the base  302 , extending beyond the underside  304  thereof, is a second clamping arm  306 . The second clamping arm  306  cooperates with the first clamping arm  226 . It has a first region (middle region)  308  which has arranged thereon a second region  310  extending towards the one side and a third region  312  extending towards the other side. In particular, the first region, the second region and the third region are connected together in one piece. The second clamping arm  306  is rigidly connected to the base  302  via the third region  312 . 
     The second region  310  is located in an angled relationship to the first region  308 . An angle  314  is adapted to the angle  242  for the first clamping arm  226 . In particular, the angle  314  is a right angle. 
     In a starting position in which the first region  232  of the first clamping arm  226  and the first region  308  of the second clamping arm  306  are oriented at least approximately parallel to each other and in which the handle  244  is pivoted towards the handle element  222 , the second region  310  of the second clamping arm  306  and the second region  234  of the first clamping arm  226  are aligned at least approximately in line with each other. 
     Pivotally located on the second region  310  of the second clamping arm  306  is a contact element  316  for a workpiece. A workpiece is capable of being clamped between the first clamping arm  226  and the second clamping arm  306 , in contacting relationship against the respective contact elements  238  and  316 . 
     The clamping tool  300  is configured in the form of pliers and is configured in particular in the form of locking pliers. In the open position of the clamping arms  226 ,  306 , in which position the handle  244  is pivoted away from the handle element  222  (this would correspond to the position shown in  FIG. 1 ), a jaw between the contact elements  238  and  316  is open. Pivoting the handle  244  in a direction towards the handle element  222  allows a workpiece to be clamped between the first clamping arm  226  and the second clamping arm  306  and then for example to be transported. 
     An operator can grasp the handle  244  and the handle element  222  in one hand. 
     The locking pliers  300  have a toggle lever. The toggle lever force is adjustable via the adjustment device  268  analogously to what has been described above for the case of the toggle clamp  10 . 
     The mechanism corresponds to the mechanism as described in connection with the toggle clamps  200  and  10 . 
     LIST OF REFERENCE CHARACTERS 
       10  toggle clamp (first exemplary embodiment) 
       12  base 
       14  support 
       16  first joint 
       18  first pivot axis 
       20  clamping arm 
       22  first region 
       24  second region 
       26  end 
       28  contact element 
       30  holding ball 
       32  receptacle 
       34  holding pin 
       36  second joint 
       38  second pivot axis 
       40  handle 
       42  first region 
       44  second region 
       46  angle 
       48  grip element 
       52  contact region 
       54  third joint 
       56  third pivot axis 
       57  bridge element 
       58  guide 
       60  first wedge element 
       62  direction of displacement 
       64  guide surface 
       66  underside 
       68  first wedge surface 
       70  fourth joint 
       72  fourth pivot axis 
       74  second wedge element 
       75  intermediate element 
       76  direction of displacement 
       78  guide 
       80  second wedge surface 
       82  upper side 
       84  wall 
       86  spring device 
       88  rear wall 
       90  direction of force 
       92  adjustment device 
       94  operative element 
       96  contact surface 
       98  holder 
       100  fifth joint 
       102  fifth pivot axis 
       104  adjusting element 
       106  region 
       108  double-headed arrow 
       110  direction of motion 
       112  air gap 
       114  angle 
       116  direction of longitudinal extent 
       120  toggle clamp (second exemplary embodiment) 
       122  base 
       124  first joint 
       126  clamping arm 
       128  second joint 
       130  handle 
       132  guide 
       134  first wedge element 
       136  second wedge element 
       137  intermediate element 
       138  bridge element 
       140  third joint 
       142  fourth joint 
       144  spring device 
       146  recess 
       148  direction 
       150  grip element 
       152  angle 
       160  toggle clamp (third exemplary embodiment) 
       162  base 
       164  first joint 
       166  first pivot axis 
       167  clamping arm 
       168  second joint 
       170  second pivot axis 
       172  handle 
       174  third joint 
       176  third pivot axis 
       178  bridge element 
       180  guide 
       182  first wedge element 
       183  intermediate element 
       184  fourth joint 
       186  fourth pivot axis 
       188  second wedge element 
       190  direction 
       192  angle 
       194  spring device 
       196  rear wall 
       200  toggle clamp (fourth exemplary embodiment) 
       202  base 
       204  underside 
       206  pin 
       208  head 
       210  slot 
       212  plate 
       214  fastening element 
       216  first region 
       218  second region 
       220  groove 
       222  handle element 
       224  direction of longitudinal extent 
       226  (first) clamping arm 
       228  pivot bearing 
       230  first pivot axis 
       232  first region 
       234  second region 
       236  third region 
       238  contact element 
       240  pivot axis 
       242  angle 
       244  handle 
       246  pivot bearing 
       248  second pivot axis 
       250  third pivot axis 
       252  bridge element 
       254  first wedge element 
       256  guide 
       258  first wedge surface 
       260  second wedge surface 
       262  second wedge element 
       264  pivot bearing 
       266  fourth pivot axis 
       268  adjustment device 
       270  spring device 
       300  locking pliers (fifth exemplary embodiment) 
       302  base 
       304  underside 
       306  second clamping arm 
       308  first region 
       310  second region 
       312  third region 
       314  angle 
       316  contact element.