Abstract:
The invention relates to a jointed support structure, in particular for the adjustable attachment of objects, such as medical instruments, to a support, such as a surgical operating table, comprising at least one clamping element having a movable clamping jaw; at least one elongate connecting element connected at one end to the clamping element and preferably made as a tube; an actuating block connected to the other end of the connecting element; at least one push rod extending at least substantially parallel to the connecting element and connecting the clamping jaw and the actuating block in a thrust transmitting manner; a movement generating device generating a movement extending at least substantially perpendicular to the push rod; and a transmission mechanism which guides the motion generated by the movement generating device while preferably deflecting it through 90° to the push rod, whereby the clamping jaw can be brought alternately into and out of clamping engagement. The transmission mechanism comprises a toggle lever mechanism having first and second toggle levers connected at a joint movable by the movement generating device to move the toggle levers and the push rod to effect clamping of the clamping jaw.

Description:
FIELD 
     The invention relates to a jointed support structure in accordance with the preamble of claim  1 . 
     BACKGROUND 
     Such a jointed support structure, also known as an arm system, is used, for example, when surgical operation areas have to be kept free for or accessible to the surgeon for a longer period. The surgical assistants are relieved in this way and can carry out other work. Such jointed support structures are used to special advantage with operations on hip joints, the abdomen, thorax, mamma and femur. They can also serve as holders in the endoscopy field. The jointed support structure is generally fastened to an operating table rail via a fastening rod and a fastening vice. After a suitable longitudinal displacement and/or horizontal adjustment, surgical aids such as valves or holders are fastened in the mounting provided at the other end of the jointed support structure, preferably as a screw clamp apparatus, and fixed in place via the movement generating device by tightening the central joint. Such jointed support structures can be used as holders in the anaesthetic or intensive care fields or in the minimum invasive field. 
     In a jointed support structure known from German patent DE 27 17 828, the transmission mechanism is formed by a ball arranged in a wedge-shaped recess which converts an axially applied clamping force into a displacement of the push rod. It is disadvantageous with this known jointed support structure that a substantial amount of force is required on the sides of the movement generating device for the clamping force generated in the clamping jaw element. Furthermore, when the torque is reduced to release the clamping jaw, self-locking can occur so that the release of the clamping is not reliably ensured. Finally, the path reserve of the transmission mechanism of the known jointed support structure is relatively low. A further embodiment operates with a spring plate centrally subject to the pressure of the movement generating device and exerting pressure by its ends on the push rod or the housing of the actuating block. The disadvantage here is that substantial forces are required to exert pressure on the push rod, in particular with an increasing deflection of the spring plate. 
     A jointed support structure which operates with only one toggle lever has also become known (Swiss patent CH 678 097) which has the disadvantage that the reaction force exerted on a conical nut by the toggle lever results in substantial friction forces between the collet and the surrounding housing, which allows self-locking on the one hand and makes the actuation of the jointed support structure more difficult on the other. 
     It is the object of the invention to provide a jointed support structure of the kind first mentioned in which 
     a specific clamping force can be achieved in the clamping jaw element with a reduced expenditure of force at the actuating block; 
     a self-locking of the transmission mechanism is not to be expected when the actuating force falls off; and 
     a larger path reserve is available. 
     The features of the characterising part of claim  1  are provided to satisfy this object. 
     SUMMARY 
     The path generating device and the toggle lever mechanism are to be made and arranged in such a way that when the largest path is set with the path generating device, the toggle lever is just not yet fully extended so that when the actuating force falls off, a reliable relaxation, i.e. the movement of the toggle lever mechanism into a position with a greater angle, i.e. an unclamping free of self-locking, is ensured. 
     Moreover, a greater path reserve is also made available due to the toggle lever mechanism, whereby any changes in length of the individual components due to material fatigue and the resulted dreaded loss in clamping power is compensated and/or countered. In this way, overhauls or repairs of the jointed support structure due to a substantial reduction in or loss of the clamping force are avoided. 
     A clamping force approximately ⅔ higher than the state of the art can be achieved on the basis of the invention with a lower tightening torque or release torque for the same construction and size. In this way, the scope of application and use of the jointed support structure, which is particularly in the field of medical technology, is substantially expanded. 
     The embodiment of claim  2  has the advantage that the toggle lever system only acts on a single push rod and that a clear relation exists between the movement generating device and the clamping procedure. 
     The embodiments in accordance with claims  3  and  4  are of particular advantage as, in this way, a particularly stable toggle lever mechanism is achieved which can be manufactured and assembled economically and which can be ideally accommodated in a space-spacing manner in the actuating block, which preferably has a circular horizontal cross section. 
     Expedient practical developments of the invention can be found in the claims  5  to  12 . 
     The embodiment of claim  13  is particularly advantageous as, in this way, two clamping jaw elements are provided which are connected to one another by the tubular connection elements and the actuating block with one of the clamping jaw elements, for example, being fastened in a suitable manner to the operating table while the other end carries the required medical instruments and/or apparatus. 
     The two housings can contact one another frictionally and are pressed more or less against one another when the movement generating device is actuated. A respective embodiment is defined in claim  14 . 
     The further developments in accordance with claims  15  to  18  are, however, particularly advantageous because, in this way, the friction between the two housings clamped relative to one another can be increased in a desirable manner. As the reduction in force achieved by the toggle lever arrangement in accordance with the invention also reduces the clamping force between the two housings contacting one another, it is expedient to increase the friction forces between the two housings by the respective measures. 
     The sliding insert can furthermore prevent metal from rubbing on metal, whereby seizing could occur. The sliding insert can be made, for example, of a suitable plastic material in order, in connection with its special dual tapering shape, to avoid seizing on a relative rotation of the two housings, on the one hand, but also to make available the required friction force, on the other hand, so that after the stressing of the two push rods a relative rotation of the two housings is reliably avoided. 
     A further development is characterised by claim  19 . 
     The preferred embodiment of the connection element as a tube can be seen from claim  20 . 
     The embodiment in accordance with claim  21  is useful to counter a relative rotation between the pressure plate, housing and toggle levers. Two advantageous embodiments for the rotational security can be seen from claim  22 . 
     A particularly good, low-friction force transmission between the toggle lever mechanism and the push rod is achieved by the measure in accordance with claim  23 . 
     An optimum length adaptation of the push rods to a particular problem can be achieved easily in accordance with claim  24 . In addition, various tube connection elements of different length are to be made available. An appropriate arrangement and design of the clamping jaw elements can be seen from claim  25 . 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is described in the following by way of example with reference to the drawing in which are shown: 
     FIG. 1 a partly sectioned side view of a jointed support structure in accordance with the invention having two toggle lever mechanisms and two clamping jaw elements in the unclamped state; 
     FIG. 1 a  a corresponding side view of a further embodiment; 
     FIG. 2 an enlarged section of FIG. 1 in the region of the upper half of the actuating block, with the toggle lever mechanism additionally being indicated in the position corresponding to clamping by a chain-dotted line; 
     FIG. 2 a  an enlarged section of FIG. 1 a  in the region of the upper half of the actuating block, with the toggle lever mechanism additionally being indicated in the position corresponding to clamping by a chain-dotted line; 
     FIG. 3 a view of the middle part of the object of FIG. 1 in the clamped state; 
     FIG. 3 a  a view of the middle part of the object of FIG. 1 a  in the clamped state; 
     FIG. 4 a schematic sectional view according to line IV—IV in FIG. 1; 
     FIG. 4 a  a schematic sectional view according to line IVa—IVa in FIG. 1 a;    
     FIG. 5 an enlarged top view of the toggle lever plates connected by pressure rollers of the embodiment in accordance with FIGS. 1,  2 ,  3  and  4 ; 
     FIG. 5 a  an enlarged top view of the toggle lever plates of the embodiment in accordance with FIGS. 1 a ,  2   a ,  3   a  and  4   a  connected by pressure rollers; 
     FIG. 6 a schematic view according to line VI—IV in FIG. 5; 
     FIG. 6 a  a schematic view according to line VIa—IVa in FIG. 5 a;    
     FIG. 7 a side view of the toggle lever plate arrangement of FIG. 5, with, however, the two toggle lever plates being shown in the state kinked relative to one another; 
     FIG. 7 a  a side view of the toggle lever plate arrangement of FIG. 5 a , with, however, the two toggle lever plates being shown in the state kinked relative to one another; 
     FIG. 8 a vertical section through a pressure plate of the embodiment in accordance with the invention according to FIGS. 1,  2 ,  3 ,  4 ,  5 ,  6  and  7 . 
     FIG. 8 a  a vertical section through a pressure plate of the embodiment in accordance with the invention according to FIGS. 1 a ,  2   a ,  3   a ,  4   a ,  5   a ,  6   a  and  7   a.    
     FIG. 9 a view of the object of FIG. 8 from the left; 
     FIG. 9 a  a view of the object of FIG. 8 a  from the left; 
     FIG. 10 a sectioned view of the housing belonging to the pressure plate in accordance with FIGS. 8 and 9 with a fitted connecting tube; 
     FIG. 10 a  a section view of the housing belonging to the pressure plate in accordance with FIGS. 8 a  and  9   a  with a fitted connecting tube; 
     FIG. 11 a partly sectioned top view of the object of FIG. 10; 
     FIG. 11 a  a partly sectioned top view of the object of FIG. 10 a;    
     FIG. 12 a sectional view of the lower housing part to be assembled with the housing in accordance with FIG. 10 a  with a fitted connecting tube; 
     FIG. 13 a top view of the object of FIG. 12; 
     FIG. 14 a side view partly sectioned analogue to FIGS. 1 and 1 a  of a further embodiment of the jointed support structure in accordance with the invention; 
     FIG. 15 a partly sectioned side view of the sliding insert using in the embodiment in accordance with FIG.  14 : 
     FIG. 16 a view of the object of FIG. 15 from the left; and 
     FIG. 17 a partly sectioned, enlarged section of FIG. 14 analogue to FIGS. 2,  2   a.   
    
    
     DETAILED DESCRIPTION 
     In accordance with FIGS. 1,  1   a ,  2 ,  2   a  and  4 ,  4   a , an actuating block  15  has two halves  15 ′,  15 ″ contacting one another with their bases along a contact plane  35  which each comprise a shell-like housing  34  (FIGS. 10,  10   a ,  11 ,  11   a ) having a substantially circular horizontal cross-section and a pressure plate  23  (FIGS. 8,  8   a ,  9 ,  9   a ) arranged displaceably therein. In each case, a recess is located between the pressure plates  23  and the housings  34  and a toggle lever mechanism  17  is accommodated therein comprising two toggle lever plates  20 ,  21  shown in detail in FIGS. 4 to  6  and a toggle lever joint  19  effective between them which is formed by two pressure rollers  19 ′ which are accommodated in grooves  20 ″,  21 ″ which are provided in the straight sides  20 ′,  21 ′ of the toggle lever plates  20 ,  21 . 
     The toggle lever plates  20  are arranged in the recesses  22  such that the one toggle lever  20  is supported with its bulge-like rounded end  46  on the peripheral margin of the housing  34 , while the free end  37  formed like a bulge of the other toggle lever  21  is connected in a thrust transmitting manner to a groove  36  formed complementary thereto in the one face of a push rod  16  which is guided displaceably in a tube  14  branching transversely from the housing  34 , extending perpendicular to the direction of movement of the toggle lever joint  19  and connected at the ends remote from the halves  15 ′,  15 ″ in each case to a clamping jaw element  11  which contains a clamping jaw  13  acted upon by the push rod  16  and a clamping member  12  formed as a ball, to which a screw clamp element  28  or a screw neck  29  is attached. The toggle lever plates  20 ,  21  are angled relative to each other both in the relaxed position (FIGS. 1,  1   a ,  2 ,  2   a ) and the stressed position (FIGS. 3,  3   a ) such that no self-locking occurs. The angle greater than 180° is located on the sides of the two toggle lever pairs facing away from one another. 
     The end of the connecting tube  14  remote from the actuating block  15  is provided with a male thread  38  onto which a respective conical nut  39 ,  39 ′ is screwed which cooperates with a complementary ball sleeve nut  40 ,  40 ′ such that a ball sleeve  41 ,  41 ′ having a cup  42 ,  42 ′ for the clamping ball  12 ,  12 ′ and connected to the ball sleeve nut  40 ,  40 ′ by a threaded connection  47 ,  47 ′ makes a strong connection between the clamping ball  12 ,  12 ′ and the connecting tube  14  when the clamping jaw  13 ,  13 ′ is acted upon by the push rod  16 . The ball sleeve  41 ,  41 ′ has sections (not shown) at the side in the region of the clamping ball  12 ,  12 ′ which allow the clamping balls  12 ,  12 ′ to be pivoted with the tube neck  29  in both directions through around 90° around a vertical axis out of the position in accordance with FIG.  3 . Furthermore, the clamping ball  12 ,  12 ′ is pivotable around the axis of the push rod  16  in the unclamped state. 
     The push rod  16  is divided in two by it comprising a short inside piece  16 ′ having the groove  36  and an outer longer piece  16 ″ which connects the flat end face of the piece  16 ′ flatly at  48  (FIGS. 1,  1   a ) and acts on the clamping jaw  13 ,  13 ′ with its other end. 
     While the clamping jaw element  11 , which is fastened to a support structure connected to the operating table via a screw neck, is made relatively solidly and firmly, because it has to bear not only the actuating block  15 , but also the medical instruments and apparatus fastened to the other end, the clamping jaw element  11 ′ provided at the opposite end is made considerably smaller and weaker because it only has to bear the weight of the attached medical instruments and apparatus via the screw clamp. 
     To actuate the toggle lever mechanism  17 , a movement generating apparatus  18  is provided in the actuating block  15  and has a draw bolt  25  with a lower head  25 ″ and an upper threaded end  25 ′ extending through bores  24  in the pressure plates  23  and housings  34  forming the actuating block  15  and whose axis  49  extends perpendicularly to the push rods  16 . Alternatively, a pneumatic or hydraulic pulling or pressing cylinder an eccentric clamping cam or similar could also be used for movement generation. 
     A threaded end  25 ′ of the draw bolt  25  protrudes from the upper pressure plate  23  at the top and a nut element  26  is screwed thereon and can be turned by a transversely arranged T-bar  27 . An upper plate arrangement  30  transmits the movement or force exerted by the nut element  26  onto the upper pressure plate  23 , while the reaction force is transmitted by the lower head  25 ″ of the draw bolt onto the lower pressure plate  23 . 
     A movement limiting screw  44  is inserted through a bore  50  (FIGS. 1,  1   a ) in the upper region of the nut element  26  and is screwed into a coaxial threaded bore  45  of the draw bolt  25  up to a predetermined depth, whereby the nut element  26  can only be unscrewed from the draw bolt  25  until the head of the movement limitation screw  44  contacts the upper edge of the bore  50 . In this way, the range of movement of the toggle lever joint  19  is limited in the relaxation direction. 
     Furthermore, the nut element  26  has an annular step  51  above the upper face of the draw bolt  25  which could generally be used for the limitation of the movement of the nut element  26  in the direction of the toggle lever plate arrangement  20 ,  21 . However, the embodiment particularly visible from FIGS. 2,  2   a  is preferred for this purpose, whereby the shell-shaped housings  34  have an annular step  52  projecting radially outwardly at a spacing from the base serving to receive the toggle lever in the most extended state and whereby this annular step  52  limits the inward movement of the pressure plates  23 . In this way, too great an extension of the toggle lever mechanism  17  beyond the chain-dotted position in FIGS. 2,  2   a  is effectively avoided. It is therefore preferred when the movement of the toggle lever plates  20 ,  21  is only restricted in the direction of the toggle lever extension by the pressure plates  23  contacting the annular step  52  which is provided in the lower half  15 ″ at the peripheral edge of the housing  34 . 
     In the assembled state, central recesses  43  (FIGS. 4,  4   a ) of the toggle lever plates  20 ,  21  surround the draw bolt at a small distance in such a way that the toggle lever plates can move freely within the range provided under the action of the movement generating apparatus  18 . 
     In accordance with FIGS. 4,  4   a , one pressure roller  19 ′ is accommodated in each of the grooves  20 ″,  21 ″ (FIGS. 7,  7   a ) on both sides of the draw bolt  25 . The depth of the grooves  20 ″,  21 ″ is dimensioned so that there is no risk of the pressure rollers  19 ′ jumping out even in the most angled state (FIGS. 1,  1   a ,  2 ,  2   a ,  7 ,  7   a ). 
     The pressure rollers  19 ′ are acted upon from the top or bottom by the pressure plates  23 , whereby a relatively wide-area force introduction and transmission is achieved. 
     In accordance with FIGS. 1,  2 ,  3 ,  4 ,  8 ,  9 ,  10 ,  11 , the pressure plates  23  and the bases of the housings  34  have radial recesses  31  and  33  respectively which are axially opposite one another and in which a rotational security pin  32  (see also FIGS. 5,  6 ,  7 ) engages which extends from the toggle lever plate  20  into the recesses  31 ,  33  in opposite directions. 
     The dimensioning must be such that the movement of the toggle lever mechanism is not hindered by the arrangement of the rotational security pin  32  in the elongate hole-like recesses  31 ,  33  during clamping and unclamping, but a relative rotation is avoided between the pressure plates  23 , the toggle lever mechanism  17  and the housings  34 . 
     A relative rotation between the toggle lever plates  20 ,  21  and the housing  34  is avoided by the rotational security pin  32  engaging into the recesses  31 ,  33 . Furthermore, the pressure plate cannot rotate relative to the housing or the toggle lever plates  20 ,  21  either due to the engagement of the rotational security pin  32  in the recess  31 . 
     Another possibility of rotational security between the housing  32  and the toggle lever plates  20 ,  21  can be seen from FIGS. 1 a ,  2   a ,  3   a ,  4   a ,  5   a ,  6   a ,  7   a ,  8   a ,  9   a ,  10   a ,  1   1   a . It can be seen in particular from FIGS. 4 a ,  5   a ,  6   a ,  8   a ,  9   a ,  11   a  and  13  that a relative rotation of the toggle lever plates  20 ,  21  relative to the housing  34  is not possible around the axis  49  can be achieved by a flat  54  at the sides of the toggle lever plates  20 ,  21  adjacent to the toggle lever joint  19  and by a counter-flat  54 ′ opposite the flat  54  that. 
     The rotational security of the pressure plates  23  can be achieved in a corresponding manner in accordance with FIGS. 8 a  and  9   a  by the pressure plate also having a flat  54  opposite the counter-flat  54 ′ of the housing  34  (FIGS. 8 a ,  9   a ). 
     While in the embodiment in accordance with FIGS. 1,  2 ,  3 ,  4 ,  5 ,  6 ,  7 ,  8 ,  9 ,  10 ,  11 , the bases of the housings  34  contacting one another along the plane of symmetry  35  are arranged extending in a planar and perpendicular fashion with respect to the axis of rotation  49 , in the embodiment in accordance with FIGS. 1 a ,  2   a ,  3   a ,  10   a , the regions of the bases of the housings  34  contacting one another are made conically complementary to one another. 
     As can be seen in particular from FIGS. 2 a  and  3   a , the upper housing  34  has a cone region  35  projecting towards the opposite housing  34  and engaging in a cone recess  56  complementary thereto in the base of the lower housing  34  arranged as a mirror image to the plane of symmetry  35 , this being done in such a way that the cone surfaces of the cone region  55  and of the cone recess  56  contact one another. For this purpose, a gap  61  is located between the planar-end surfaces of the housings  34  (FIG. 2 a ). 
     In this way, the friction torque between the two housings  34  is increased in the region of the plane of symmetry  35  so that adequate clamping against a relative rotation of the two housings  34  is achieved even when there is only a low clamping of the two housings  34  against one another. The housings  34  are securely fixed in place in this manner despite the low tightening force. In addition, the cone form fixes the central joint in place radially. The radial forces which occur no longer have to be borne by the draw bolt  25 , which represents a substantial improvement. 
     In the embodiment in accordance with FIGS. 14 to  17 , the two housings  34  with base regions opposite one another each have a recess  59  with a peripheral cone surface  58  in the base region. A sliding insert  57 , formed in accordance with FIGS. 15,  16 , engages in this recess and is provided with cone surfaces  60  which are in a mirror-symmetrical position relative to the plane of symmetry  35  and which extend complementary to the peripheral cone surfaces  58  of the recesses  59 . The dimensioning is such that the sliding insert  57  retains the two housings  34  at a low spacing to one another. The thickness of the sliding insert  57  is selected so that a gap  61  remains between the planar upper and lower surfaces, on the one end, and the opposing planar surfaces of the cone recesses  56 . This gap  61  ensures that the force transmission is effected solely via the peripheral cone surfaces  58 . The sliding insert  57  in accordance with FIGS. 15,  16  has a central bore  24 ′ for the passage of the draw bolt  25 . 
     The sliding insert  57  consists of a suitable sliding material which prevents scratching noise during the relative movement of the two housings  34  and any eroding of the contact surfaces without impairing the retaining function. For this purpose, the sliding insert  57  is preferably made of a suitable plastic material. 
     The assembly and the use of the support structure in accordance with the invention are as follows: 
     During assembly, the ball sleeve nut  40 ,  40 ′ is the first element set on the tube  14 . The ball sleeve nut  40 ,  40 ′ is not initially tight, but rotatable and axially displaceable on the tube  14 . Only when the conical nut  39 ,  39 ′ is screwed on is the ball sleeve nut  40 ,  40 ′ fixed axially in place in the direction of the clamping force. 
     If the ball sleeve  41 ,  41 ′ with the clamping jaw  13 ,  13 ′ and the clamping ball  12 ,  12 ′ is now screwed onto the ball sleeve nut  40 ,  40 ′, the threaded joint  47 ,  47 ′ is created and a rotatable, but not axially displaceable joint is produced. 
     If then a clamping force acts on the clamping jaw  13 ,  13 ′ via the toggle lever plates  20 ,  21  and the push rod  16 , this has the effect that the clamping jaw element  11 ,  11 ′ is fixed axially in place and against rotation. 
     When the clamping force is released, a rotation of the clamping jaw elements  11 ,  11 ′ on the tube  14  is still possible without any axial play due to the length matching of the push rods  16 . This clamping or the possibility of rotating without play of the clamping jaw elements contributes to providing a jointed support structure which allows maximum movement in the unclamped state and can be brought into a rigid state by a central actuation. 
     First, the tube neck  29  is attached vertically and longitudinally displaceably to an operating table, for example, via a support structure rod and a clamping block. 
     Subsequently, the surgical aids, e.g. a medical instrument or a medical apparatus, is clamped in the screw clamp arrangement  28 . 
     Now, with the toggle lever mechanisms  17  still relaxed, the desired relative position is set between the tube neck  29  and the screw clamp arrangement  28 , with the clamping balls  12 ,  12 ′ being able to be adjusted largely freely within the cups  42 ,  42 ′ or the clamping jaws  13 ,  13 ′. Furthermore, the connecting tubes  14  can be relative to one another in the desired manner angle-wise around the axis  49  of the actuating block  15 . 
     As soon as the desired relative position of the individual components is reached, the T-bar  27  is rotated in the clockwise direction (FIGS. 1,  1   a ,  2 ,  2   a ) to move the toggle lever mechanisms  17  out of the relaxed position in accordance with FIGS. 1,  1   a , into the clamping position in accordance with FIGS. 3,  3   a , whereby the push rods  16  are displaced in the direction of the clamping jaws  13 ,  13 ′ until the clamping jaws  13 ,  13 ′ press the clamping balls  12 ,  12 ′ firmly against the cups  42 ,  42 ′. At the same time, the two housings  34  are pressed firmly onto one another in the region of the plane of symmetry  35  so that a further relative rotation of these is no longer possible. The cone arrangement  55 ,  56  in accordance with FIGS. 2 a ,  3   a  and/or the sliding insert  57  in accordance with FIGS. 14 to  16  contribute in particular to this. By a suitable selection of the cone angle of the cone arrangement  55 ,  56  or the peripheral cone surface  58  a situation can be achieved in which a substantial resistance force against relative rotation of the two halves  15 ′,  15 ″ of the actuating block  15  is achieved even with relatively low clamping forces generated by the movement generating apparatus  18 . The support structure is now ready for use. 
     To safely avoid the draw bolt  25  being turned when the nut element  26  is tightened, a rotational security pin  53  (FIGS. 1,  1   a ,  9 ,  9   a ) is attached between its head  25 ″ and the lower pressure plate  23 . 
     The clamping forces during the rotation of the nut element  26  in the clamping direction are transmitted from the nut element  26  to the pressure plates  23  via the plate arrangement  30  or the head  25 ″ and from there to the pressure rollers  19 ′ of the toggle lever mechanisms  17 . In this way, substantial spreading forces are created which act on the push rods  16 . Relatively large adjustment paths can be achieved in a space-saving manner by the use of a toggle lever mechanism  17  as the transmission. Such a substantial force amplification is achieved in the approximately extended state of the toggle lever  20 ,  21  (FIGS. 3,  3   a ) that a faultless clamping of the clamping balls  12 ,  12 ′ is achieved which is also easily releasable again because the toggle levers  20 ,  21  return back to the relaxed position in accordance with FIGS. 1 or  1   a  (shown in solid lines) without any problem and without any risk of self-locking on release of the nut element  26 . The adjustment of the toggle lever  20 ,  21  is possible with an extremely low effort force due to the arrangement in accordance with the invention. 
     The two axially displaced connecting tubes  14  pointing in opposite directions are pivotable relatively to one another through 360° around the axis  49  in the unclamped state and can be fixed in place at any relative angular position relative to one another by tightening the clamping nut  26 , whereby the two halves  15 ′,  15 ″ of the actuating block  15  are pressed against one another. 
     The clamping jaw element  11 ,  11 ′ allows the pivoting of the clamping balls  12 ,  12 ′ through 180° around a vertical axis due to the lateral slots (not shown). 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Reference symbol list 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 11 
                 Large clamping jaw element 
               
               
                   
                 11′ 
                 Small clamping jaw element 
               
               
                   
                 12 
                 Large clamping member (clamping ball) 
               
               
                   
                 12′ 
                 Small clamping member (clamping ball) 
               
               
                   
                 13 
                 Large clamping jaw 
               
               
                   
                 13′ 
                 Small clamping jaw 
               
               
                   
                 14 
                 Connecting element (connecting tube) 
               
               
                   
                 15 
                 Actuating block 
               
               
                   
                 15′ 
                 Half 
               
               
                   
                 15″ 
                 Half 
               
               
                   
                 16 
                 Push rod 
               
               
                   
                 16′ 
                 First piece of the push rod 
               
               
                   
                 16″ 
                 Second piece of the push rod 
               
               
                   
                 17 
                 Toggle lever mechanism 
               
               
                   
                 18 
                 Movement generating device 
               
               
                   
                 19 
                 Toggle lever joint 
               
               
                   
                 19′ 
                 Pressure roller 
               
               
                   
                 20 
                 Toggle lever plate 
               
               
                   
                 20′ 
                 Straight side 
               
               
                   
                 20″ 
                 Groove 
               
               
                   
                 21 
                 Toggle lever plate 
               
               
                   
                 21′ 
                 Straight side 
               
               
                   
                 21″ 
                 Groove 
               
               
                   
                 22 
                 Recess 
               
               
                   
                 23 
                 Pressure plate 
               
               
                   
                 24 
                 Bore 
               
               
                   
                 24′ 
                 Bore 
               
               
                   
                 25 
                 Draw bolt 
               
               
                   
                 25′ 
                 Threaded end 
               
               
                   
                 25″ 
                 Head 
               
               
                   
                 26 
                 Nut element 
               
               
                   
                 27 
                 T-bar 
               
               
                   
                 28 
                 Screw clamping device 
               
               
                   
                 29 
                 Screw neck 
               
               
                   
                 30 
                 Plate arrangement 
               
               
                   
                 31 
                 Recess 
               
               
                   
                 32 
                 Rotational security pin 
               
               
                   
                 33 
                 Recess 
               
               
                   
                 34 
                 Housing 
               
               
                   
                 35 
                 Contact plane 
               
               
                   
                 36 
                 Groove 
               
               
                   
                 37 
                 End 
               
               
                   
                 38 
                 Outer thread 
               
               
                   
                 39 
                 Conical nut 
               
               
                   
                 39′ 
                 Conical nut 
               
               
                   
                 40 
                 Ball sleeve nut 
               
               
                   
                 40′ 
                 Ball sleeve nut 
               
               
                   
                 41 
                 Ball sleeve 
               
               
                   
                 41′ 
                 Ball sleeve 
               
               
                   
                 42 
                 Cup 
               
               
                   
                 42′ 
                 Cup 
               
               
                   
                 43 
                 Recess 
               
               
                   
                 44 
                 Movement limitation screw 
               
               
                   
                 45 
                 Threaded bore 
               
               
                   
                 46 
                 End 
               
               
                   
                 47 
                 Threaded joint 
               
               
                   
                 47′ 
                 Threaded joint 
               
               
                   
                 48 
                 Connection point 
               
               
                   
                 49 
                 Axis 
               
               
                   
                 50 
                 Bore 
               
               
                   
                 51 
                 Annular step 
               
               
                   
                 52 
                 Annular step 
               
               
                   
                 53 
                 Rotational security pin 
               
               
                   
                 54 
                 Flat 
               
               
                   
                 54′ 
                 Counter flat 
               
               
                   
                 55 
                 Cone region 
               
               
                   
                 56 
                 Cone recess 
               
               
                   
                 57 
                 Sliding insert 
               
               
                   
                 58 
                 Peripheral cone surface 
               
               
                   
                 59 
                 Recess 
               
               
                   
                 60 
                 Cone surface 
               
               
                   
                 61 
                 Gap