Abstract:
In a weighing cell a load receiver is constrained in a mode of planar translatory motion in relation to a stationary part ( 1 ). The stationary part ( 1 ), configured in the shape of a solid H-profile, has two side plates ( 3 ) to which the guide links of a parallelogram mechanism are attached. A base plate ( 2 ) connects the side plates ( 3 ) and supports the parts, that are required for transmitting a force to be measured from the load receiver to a measuring cell. The force-transmitting parts can be configured either as a monolithic material block or as individually assembled components. (FIG. 1)

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention concerns a force-measuring apparatus, particularly a weighing cell, with a load receiver for receiving the force that is to be measured and a force-transmitting device for transmitting at least a partial amount of the force to be measured from the load receiver to a measuring transducer that delivers a signal corresponding to the force to be measured. The load receiver is guided in planar translatory motion in relation to a stationary part of the force-measuring apparatus by two parallelogram guides (guide links) that extend in two mutually parallel planes, are rigid with regard to deformation within their respective planes and have elastic flexibility in the transverse direction of the planes. Each of the two parallelogram guides is connected at one end (with respect to its lengthwise direction) to the load receiver and at the opposite end to the stationary part of the force-measuring apparatus. A parallelogram plane is defined by the lengthwise direction of the guides and the path of motion traveled by the load receiver. The force-transmitting device has at least one force-transmitting lever that receives its input force through a coupling from the load receiver and is rotatable in relation to a fulcrum axis that is fixed on a support portion of the stationary part extending between the two parallelogram guides in a plane that is parallel to the common plane of the parallelogram guides. 
     2. Description of the Related Art 
     It is a known design concept for weighing cells of this kind to be assembled from numerous individual components that need to be either rigidly attached to or movably pivoted at the stationary part. In particular, the pivot points of the parallelogram guides and the lever are located on the stationary part. Positional changes of these pivot points that are caused by the force to be measured will impair the measuring accuracy. Therefore, the stationary part needs to have a particularly high degree of structural rigidity. 
     It is also a known concept (DE 41 19 734 A1) to configure the stationary part, the parallelogram guides, the load receiver and the lever as a continuum of interconnected material portions of a monolithic material block, whereby in particular the assembly process of the corresponding separate components is eliminated. However, the separation of the individual material portions from the material block, e.g., by the method of spark erosion, represents a relatively exacting procedure, particularly in the case where the apparatus will have to meet a high level of measuring accuracy and, therefore, the thinned-down material domains by which the material portions are movably connected have to be formed with a commensurate degree of precision. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a force-measuring apparatus of the kind described at the beginning, composed of only a small number of simple parts and offering a satisfactory level of measuring accuracy. 
     According to the invention, this problem is solved by configuring the stationary part in the shape of a base plate that forms the support portion. Two side plates, perpendicular to the plane of the base plate, extend along the borders of the base plate that run in the lengthwise direction of the parallelogram guides. The parallelogram guides at their stationary ends (i.e., the far ends from the load receiver) are anchored on the side plates. 
     The concept of a base plate and transversely extending side plates results in an exceptional degree of rigidity in the stationary part. At the same time, this shape of the stationary part offers a simple way of anchoring the ends of the parallelogram guides. The latter extend on both sides of and parallel to the base plate from their stationary ends (where they are anchored to the base plate) to their opposite, movable ends (where they are connected to the load receiver). Due to their elastic flexibility, they form a parallelogram linkage to guide the load receiver. The parallelogram plane (i.e., the kinematic plane of the motion of the load receiver) is perpendicular to the planes of the parallelogram guides and of the base plate and runs in the lengthwise (end-to-end) direction of the parallelogram guides. Given that the stationary part has a high resistance to deformation, the corner points of the parallelogram linkage will not be displaced under a load, which is beneficial for the measuring accuracy. At the same time, the stationary part has a simple shape so that its manufacture is relatively uncomplicated. 
     In an advantageous embodiment of particular simplicity, the base plate and the associated side plates are formed as a section of an integral, monolithic H-profile in which the transverse web segment of the H-profile represents the base plate and the two parallel segments of the H-profile represent the side plates. An H-profile of this kind may be produced by a simple process, e.g., as an extruded profile or a pressure casting. 
     Further in the interest of a simple design configuration, the side plates in a practical embodiment have border surface areas parallel to the planes of the parallelogram guides where the stationary ends (i.e., the far ends from the load receiver) of the parallelogram guides are attached. This is also particularly advantageous if, as in most cases, the bending flexibility of the parallelogram guides is realized by means of flexural pivots (flexures, for short) that form the ends of the parallelogram guides and have a virtual pivotal axis located between two flat attachment terminals. In this case, the parallelogram guides each have two flexures at the ends where the parallelogram guides are attached to the stationary part, with the attachment terminals extending parallel to the plane of the parallelogram guide. The attachment terminals on the side of the stationary part lie flat against and are attached to the parallel border surfaces of the side plates. The attachment terminals of the same flexures but on the opposite side of the virtual pivotal axis are attached to a rigid, plate-shaped portion of the parallelogram guide. 
     It is also within the scope of the invention that at least one of the side plates has a slit extending at least through the portion next to the place where one of the parallelogram guides is attached, the width of the slit being adjustable in the direction transverse to the plane of the parallelogram guides. By adjusting the width of the slit, e.g., by means of an adjustment screw acting on the slit, it is possible to vary the distance between the parallelogram corner next to the respective point of attachment and its neighboring corner in the transverse direction to the plane of the parallelogram guides. This allows the corrective adjustment of so-called corner-load errors that occur in particular if the force to be measured is introduced asymmetrically into the load receiver, i.e., not centered along a symmetry axis extending in the direction of the displacement. 
     In a further practical embodiment of the invention, the lever is rotatably constrained on the stationary part by at least one flexure with two attachment terminals and a virtual pivotal axis located between them, where one attachment terminal is fastened to the stationary part, the other attachment terminal is fastened to the lever, and the virtual pivotal axis constitutes the lever fulcrum. In this arrangement, the flexure constitutes an immediate rotatable constraint of the lever to the stationary part where, due to the shape of the stationary part, a suitable attachment surface can be made available without a problem. 
     This fulcrum constraint of the lever is configured to particular advantage in an embodiment of the invention where the two side plates of the stationary part each have a frontal attachment area extending in a plane perpendicular to the lengthwise direction of the parallelogram guides, with the fixed, stationary end of a flexure fastened to each attachment area, and where the lever has a pivotal portion extending between and fastened to the opposite, flexing ends of the flexures. In this arrangement, the pivotal portion of the lever extends across the entire width of the stationary part as measured from one side plate to the other and thus requires a particularly sturdy form of construction that takes advantage of the overall shape of the stationary part. 
     This embodiment may be further developed in such a way that the pivotal portion is arranged in front of the load receiver, i.e., when looking in the lengthwise direction of the parallelogram guides from the movable, load-receiver ends of the parallelogram guides towards their opposite ends where they are attached to the stationary part. With this arrangement, the greatest amount of space is available for the useful lever length in the lengthwise direction of the parallelogram guides. Also, the attachment terminals of the flexures are openly accessible and easy to install. 
     As an alternative, the pivotal portion may be arranged to the rear of the load receiver, i.e., when looking in the lengthwise direction of the parallelogram guides from the movable, load-receiver ends of the parallelogram guides towards their opposite ends where they are attached to the stationary part. With this arrangement, the entire space in front of the pivotal portion of the lever is available for the load receiver so that the latter may be of a particularly sturdy design. 
     According to another inventive idea, the device for transmitting the force to be measured comprises a monolithic material block that is traversed by material-free free spaces extending transverse to the parallelogram plane (the latter being defined by the lengthwise direction of the parallelogram guides and the travel direction of the load receiver). The material-free spaces delimit a material portion that is anchored on the base plate of the stationary part, another material portion forming the lever, and a thinned-down material connection between the two in the form of an elastically flexible domain representing the fulcrum pivot of the lever. 
     This embodiment eliminates the need for assembling a separate flexural pivot for the fulcrum support because the lever, the elastically flexible portion and the material portion mounted on the base plate are integrally connected to each other. The flexural domain being formed in one integral piece together with the lever has the advantage that no screw connections are necessary. Also, the material block and the material portions delimited within it can be very small and compact. In addition, the areas that are critical for the measuring accuracy, particularly the flexural fulcrum of the lever, can be produced with narrow tolerances. 
     In a practical further development of this embodiment, a portion of the material block is delimited by a material-free space traversing the block perpendicularly to the parallelogram plane and thereby forming a coupling member. At its one end, the coupling member is integrally connected to the lever arm that takes up the force from the load receiver. The opposite end of the coupling member is attached to the load receiver. In this arrangement, the coupling member for the connection to the lever, too, hangs together with the lever as one single piece, which enhances the simplicity of the design. The end of the coupling member nearest the load receiver is attached to the latter with one or more screws. The coupling member is rigid in the direction of the force to be transmitted by it while being elastically flexible in the perpendicular direction in the parallelogram plane so that it can yield to the deflections of the load receiver and the lever. The elastic flexibility is provided by thinned-down flexural domains in the areas where the coupling member meets the lever and the load receiver, respectively. The flexural domains can be produced to a narrow tolerance through an appropriate design of the material-free space in the material block, which is advantageous for the measuring accuracy. 
     If necessary, the device for transmitting the force to be measured may also comprise a further material-free space traversing the material block in the perpendicular direction to the parallelogram plane in such a way that at least one material portion is delineated in the form of a further lever that works in sequence after the (first) lever, and another material portion is delineated in the form of a further coupling member whose one end hangs together with an arm of the further lever and whose opposite end hangs together with the arm of the first lever that points away from the load receiver. The further lever provides an additional level of force reduction in case a sufficient reduction ratio cannot be achieved with a single lever because of spatial constraints or considerations of structural strength. In an analogous way, one or more additional levers could be arranged in sequence after the further lever, in case this were required. 
     It is particularly advantageous in all single-block embodiments of the force-transmitting device of the kind described above that at least a part of the material-free spaces are in the form of only a thin linear cut traversing the material block. Given that only very small amounts of displacement travel are required for the movable parts of the material block, the width of the thin linear cuts can be very small. The preferred method for producing thin linear cuts of this kind is by the process of spark erosion. By minimizing the dimensions of the material-free spaces, the volume available for the material portions delimited by them is maximized, which increases the flexural stiffness of the force-transmitting parts that are formed out of these material portions, whereby the measuring accuracy is enhanced. 
     In the embodiments described here, as a practical means for connecting the stationary part of the force-measuring apparatus with the device for transmitting the force to be measured, the material portion by which the device is attached to the base plate has a contact surface in form-fitting engagement with a surface area of the base plate and is firmly attached to the base plate by means of at least one screw bolt that extends parallel to the parallelogram plane. This requires no more than one bore hole per bolt in the material portion by which the device is attached to the base plate. The bolt(s) may be anchored in a tapped hole (tapped holes), e.g., in the base plate, with the bolt shaft(s) passing through the hole(s) of the attached material portion and the bolt head(s) tightened against an appropriate contact area of the attached material portion. 
     In a possible design alternative, the material portion by which the device is attached to the base plate, likewise, has a contact surface in form-fitting engagement with a surface area of the base plate. By means of at least one screw bolt that extends transverse to the parallelogram plane, the attached material portion is fastened to at least one attachment part that is connected to and stands out perpendicularly from the base plate. In contrast to the embodiment of the preceding paragraph, the at least one bolt passes through its associated hole in the attached material portion not in a parallel direction but rather in the perpendicular direction to the parallelogram plane. 
     In a further practical design alternative, the material portion by which the device is attached to the base plate has a contact surface in form-fitting engagement with a surface area of the base plate facing towards one of the parallelogram guides and also with an adjoining frontal surface area of the base plate extending transverse to the plane of the parallelogram guides. The attached material portion is fastened tightly to the base plate by means of at least one screw bolt that traverses the frontal surface area. In this arrangement, it is practical if the aforementioned surface area of the base plate faces against the direction of the force to be measured that is applied to the load receiver so that the force to be measured adds to the contact pressure between the attached material portion and the base plate. The screw bolt for the frontal attachment extends parallel to the plane of the base plate as well as to the parallelogram plane. 
     In a very advantageous configuration of the device for transmitting the force to be measured, the material block (as seen in the parallelogram plane) is L-shaped; the coupling member connecting the lever to the load receiver is formed in the part of the L that extends parallel to the load receiver; and the lever is formed in the part of the L that extends parallel to the plane of the base plate. Using this L shape permits the contact surface for the attachment to be realized in a particularly simple way in all of the embodiments. The L shape also takes into account that the lever and the coupling member extend at a right angle to each other and, therefore, the configuration of the lever and the coupling member in the two legs of the L minimizes the amount of material required for the material block. 
     The invention further includes the concept of attaching the measuring transducer to the base plate. The shape and rigidity of the base plate of the stationary part are ideally suited to support the measuring transducer and to assure and maintain its precise position in a simple manner. In many cases, the measuring transducer is an electromagnetic force compensation system. In a system of this kind, a permanent magnet that includes a magnet yoke is attached to the base plate. A compensation coil that is connected to a lever of the force-transmitting device and carries the flow of compensating current is immersed in the air gap of the magnetic circuit formed by the permanent magnet and the magnet yoke. The measuring transducer is equipped with a position sensor that monitors the position of the compensation coil within the magnetic field and generates a position-related signal by which the compensating current is regulated so that the compensation coil is held at its null position when a force is applied to the load receiver. Thus, the strength of the compensating current represents a measure for the size of the force that is to be determined. 
     Also, according to a further aspect of the invention, a support element attached to a surface area of the base plate includes a column extending at a right angle to the base plate and passing with clearance through an opening in the parallelogram guide that faces said surface area. This support element, serving as the stationary mounting base for the supporting portion of the force-measuring apparatus, can be attached to the chassis plate of a balance housing, e.g., at the opposite end of the support element, from where the latter is attached to the base plate. This concept of the support element provides a very sound arrangement for taking up the reactive forces when the force to be measured is applied. 
     Another inventive embodiment presenting a sturdy and simple configuration of the force-measuring apparatus is distinguished in that the load receiver, the parallelogram guides and the stationary part are formed as integrally connected portions of a material piece of rectangular hollow-profile: cross-section. The side plates are formed by portions of two mutually parallel side walls of the hollow profile. The base plate extends from one side wall to the other; it runs parallel to and is spaced at a distance between the transverse walls that connect the side walls of the hollow profile. The parallelogram guides are delimited in the hollow-profile piece by slits traversing the walls of the hollow profile in the lengthwise direction of the parallelogram guides. Thinned-down domains are formed in the hollow-profile piece that run in the transverse direction within the planes of the parallelogram guides from the ends of one slit to the corresponding ends of the other. These thinned-down domains function as flexural pivots at the ends of the parallelogram guides. The load receiver is delimited against the stationary part by transverse slits in the hollow-profile piece running perpendicular to the longitudinal direction. 
     This embodiment of the invention is particularly well suited for loads in the range of several hundred kilograms. In a simple manufacturing process, a hollow profile of a wall thickness adapted to the desired maximum loading strength is extruded and subsequently cut into the hollow-profile material pieces. The lengthwise and transverse slits for delimiting the parallelogram guides and the load receiver, as well as the grooves for the thinned-down domains, may be formed by basic milling and/or drilling operations either before or after the cutting. As the only remaining assembly step, the device that transmits the force to be measured from the load receiver to the measuring transducer is mounted in the hollow-profile piece and coupled to the load receiver. 
     In this context, as a practical constructive embodiment of the fundamental inventive principle, the lengthwise slits delimiting the parallelogram guides are formed in the transverse walls of the hollow profile. Thus, in particular the lengthwise slits can be arranged in the transverse walls in such a manner that the side where each slit adjoins the respective side wall is flush with the inner surface of that side wall. As an alternative design choice, the lengthwise slits delineating the parallelogram guides may be formed in the side walls. In this design version, the particular arrangement of the lengthwise slits is such that the side where each slit adjoins the respective parallelogram guide is flush with the inner surface of the transverse wall within which the respective parallelogram guide is formed. 
     It also helps to simplify the manufacturing process that in a further embodiment each of the thinned-down domains is bounded between a pair of grooves in the hollow-profile piece that are transversely opposite each other across the plane of the respective parallelogram guide. In a cross-section perpendicular to the plane of the parallelogram guides, the grooves have convex curvatures towards each other. The grooves extend parallel to the plane of the parallelogram guide and transverse to the longitudinal axis of the hollow-profile piece and can be formed, e.g., by drilling and/or milling. 
     As a further inventive feature, the stiffness of the flexures formed by the thinned-down domains can be made adjustable by providing cutouts traversing the hollow profile at a right angle to the plane of the parallelogram guides in the vicinity of the thinned-down domains. The length of the thinned-down domains transverse to the lengthwise direction of the parallelogram guides is given by the distance of the cutouts from the lengthwise slits. The length and thickness of the thinned-down domains determine the cross-sectional areas of the material connections where the parallelogram guides hang together at one end with the stationary part and at the other end with the load receiver. By further taking into account the properties of the material used for the hollow-profile piece, the stiffness of the flexures is quantitatively defined. 
     Furthermore, the embodiments that are based on the concept of a hollow-profile piece may be practically configured in such a way that the two side walls are extended beyond the outside surface of the transverse wall facing in the direction of the load-induced displacement of the load receiver. This allows the force-measuring apparatus to be attached by the extensions of the side walls to a chassis plate, e.g., of a balance housing. In this arrangement, the extensions provide sufficient clearance between the chassis plate and the adjacent parallelogram guide for the displacement travel of the load receiver when a load is applied. 
     In the embodiments discussed so far, at least the parallel-guiding mechanism on one hand and the force-transmitting device between the load receiver and the measuring transducer on the other hand are configured as separate units. This offers the advantage that the parallel-guiding mechanism especially for larger load capacities can be designed to have commensurate strength and sturdiness while the force-transmitting device can be configured independently to match the smaller forces that it is subjected to with a lighter but more precise design. However, an assembly process is necessary for putting together the separate units. In accordance with another aspect of the invention, the assembly phase is avoided in that the load receiver, the parallelogram guides, the stationary part and the lever are formed as monolithically interconnected material portions of a rectangular material block in which the material portions are delimited by material-free spaces traversing the material block at a right angle to the parallelogram plane. In the dimension transverse to the parallelogram plane, the material block is wider in the areas of the parallelogram guides and their delimiting material-free spaces than in the area of the lever. This gives a greater amount of strength to the parallelogram guides, which carry the greatest internal forces, while the smaller thickness of the lever portion reduces the amount of work required to form the lever. Due to their increased strength, the parallelogram guides have a greater rigidity against warping under eccentric loading conditions. This proves to be effective in preventing measuring errors caused by eccentric loading. 
     The preferred way of applying this design concept in practice is to use a material block with an H-shaped profile. In a cross-sectional plane transverse to the parallelogram plane, the two legs of the H (the flanges of the H-profile) represent the areas of greater material width and the connector section between the legs (web segment) represents the area of reduced material width. A particularly simple process for producing a material block of this shape consists of extruding H-profiled bars of greater length and cutting them into sections of the length required for the material blocks. 
     Particularly preferred are embodiments in which the material-free portions delimiting the load receiver, the parallelogram guides and the stationary part are at least in part formed only by thin linear cuts. This allows the interstices between the individual components to be as narrow as is optimally desirable, at least in the areas where this is relevant, so that the apparatus can be accommodated within a reduced amount of space in relation to a given load capacity, or the load capacity may be increased in relation to a given design volume. Detailed illustrations and descriptions are presented in the German patent application P 41 19 734.8 that was filed by the same applicant on Jun. 14, 1991 and also formed the basis for the European patent application EP 92 109 385, and further in the German patent application P 196 05 087 filed Feb. 12, 1996. The relevant features disclosed in these earlier applications are herewith included by reference. 
     In a preferred further development, the support portion of the stationary part lies adjacent to one of the two parallelogram guides directly across one of the material-free spaces. At the same time, the (first) lever that is coupled to the load receiver lies adjacent to the other of the two parallelogram guides directly across another of the material-free spaces. In this arrangement, the portion of said lever that is nearest to the adjacent parallelogram guide falls within the area of increased width of the material block, which also increases the strength of the lever. This is particularly advantageous where the force introduced from the load receiver into the lever is large and where only the subsequent levers carry a lighter load due to the lever-reduction of the first lever. This train of reasoning, too, is extensively discussed in the aforementioned earlier applications. 
     In a further practical evolution of this embodiment, the material-free space delimiting the first lever on the far side from the adjacent parallelogram guide extends in the area of reduced width of the material block. This allows further parts of the force-transmitting device to be formed immediately next to the first lever in the reduced-width area, e.g., one or more subsequent levers of a lever series as described in the aforementioned earlier applications. 
     Further distinctive features, details and advantages of the invention will become evident from the following description and from the drawing that is also being referred to for the disclosure of all details essential to the invention that are not expressly mentioned in the text. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     In the drawing: 
     FIG. 1 represents a perspective view of a stationary part of a weighing cell; 
     FIG. 2 represents a perspective view of a device for transmitting a force to be measured that is formed out of monolithic material block; 
     FIG. 3 represents a partially sectional view of a weighing cell assembled from the parts shown in FIGS. 1 and 2; 
     FIG. 4 represents a side view of a slightly modified version of the device of FIG. 2 for transmitting the force to be measured; 
     FIG. 5 represents a perspective view of the weighing cell with the device of FIG. 4 installed in it; 
     FIG. 6 represents another slight variation of the force-transmitting device of FIG. 2; 
     FIG. 7 represents a too view of the base plate with the device of FIG.  6  and other parts mounted in place; 
     FIG. 8 represents a perspective view of another embodiment of the weighing cell as seen from the side of the measuring transducer; 
     FIG. 9 represents a side view of the weighing cell of FIG. 8; 
     FIG. 10 represents a perspective view of a modified version of the weighing cell of FIGS. 8 and 9 as seen from the side of the load receiver; 
     FIG. 11 a  represent perspective views of two embodiments and  11   b  in which the parallelogram guide mechanism is formed out of a piece of hollow-profile stock. 
     FIG. 12 represents a perspective view of an embodiment with a monolithically integral configuration of the parallelogram guide mechanism and the force-transmitting device. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In a weighing cell as shown in a partially sectional view in FIG. 3, the stationary part  1  is made of a section of H-profile stock as illustrated in the perspective view of FIG. 1. A plane base plate  2  represents the transverse web segment of the H-profile. Two essentially rectangular side plates  3 , representing the vertical flange segments of the H-profile, extend along two parallel borders of the base plate  2 . In the illustration of FIG. 3, the side plate  3  closer to the viewer has been cut away and, therefore, only the side plate  3  farther from the viewer and a sectional representation of the base plate can be seen in FIG.  3 . By choosing an appropriate material thickness for the base plate  2  and the side plates  3 , the stationary part is given a high degree of structural stiffness. 
     A monolithic material block  4  of a device for transmitting the force to be measured, as shown in perspective in FIG. 2, is mounted on the base plate  2  midway between the side plates  3 . Seen in a parallel plane to the side plates - 3 , the material block  4  is L-shaped with the two legs  5  and  6  of the L being confined between two lateral boundary planes  7 ,  8 . In addition, the leg  5 , oriented horizontally in FIG. 2, is delimited between and perpendicular to the two lateral boundary planes  7 ,  8  by a plane bottom surface  9 , a parallel plane top surface  10 , and also an end surface  11  perpendicular to the bottom surface  9  and top surface  10 . The vertical leg  6  of the L, which hangs together with the horizontal leg  5 , is delimited between and perpendicular to the two lateral boundary planes  7 ,  8  by a plane front surface  12 , a parallel plane rear surface  13  and also an end surface  14  parallel to the bottom surface  9  of the horizontal leg  5 . 
     As indicated in FIG. 2 by a bold line, a thin linear cut  15  in the vertical leg  6  of the L traverses the material block  4  at a right angle to the lateral boundary surfaces  7 ,  8 . Starting from the bottom end surface  14 , the thin linear cut  15  runs at first parallel to the rear surface  13 , then curves out towards the front surface  12  where its convex shape delimits one side of a thinned-down material portion  16 . On the side of the front surface  12 , the thinned-down domain  16  is delineated by a convex curve that is the mirror-opposite of the convex shape of the thin linear cut  15  and is formed by the removal of a cylinder-segment shaped material portion  17  from the front surface  12 . For clarity, the material portion  17  in FIG. 2 is drawn as part of the material block  4 , although the material portion is totally separated by the thin linear cut  18  and removed in the finished state of the device. Continuing after the curve that delineates the thinned-down domain  16 , the thin linear cut  15  runs parallel to the rear surface  13  for some distance and then, near the top surface  10 , again curves out towards the front surface  12  where its convex shape delimits one side of a further thinned-down domain  19 . On the side of the front surface  12 , the further thinned-down domain  19  is delineated by a convex curve that is the mirror-opposite of the convex shape of the thin linear cut  15  and is formed by the removal of a cylinder-segment shaped material portion  17 ′ analogous to the material portion  17 . Like the latter, the material portion  17 ′ for the sake of clarity is shown in FIG. 2 in its non-removed state. 
     At the transition from the rectilinear segment of the thin linear cut  15  to the curved segment delineating the further thinned-down domain  19 , a further thin linear cut  20  branches off from the thin linear cut  15  and mirrors the convex-curved shape of the latter. The thin linear cut  20  delineates one side of a thinned-down domain  21 , whose other side (facing in the direction towards the end surface  11  of the leg  5 ) is delineated by a mirror image-like convex curve of a thin linear cut  22 . The convex-curved section of the thin linear cut  22  is adjoined by a straight section extending lengthwise through the L-leg  5  into t-he vicinity of the end surface  11  and converging slightly towards the top surface  10 . Near the end surface  11 , the thin linear cut  22  changes direction along a bend whose convex curvature faces towards the end surface  11 , then continues through a straight section parallel to the end surface  11  and ends in another convex-curved section facing towards the end surface  11 . The latter two curves and straight section of the thin linear cut  22  have their mirror-opposites in two curves and an intermediate straight section of a thin linear cut  23  that starts out from the end surface  11 . The two opposite pairs of curves of the thin linear cuts  22  and  23  delimit thinned-down domains  24 ,  25  that are aligned in parallel with the end surface  11 . Continuing after the thinned-down domain  25  that is nearer to the bottom surface  9  of the L-leg  5 , the thin linear cut  23  turns back into a direction towards the top surface  10  and ends in a bend with a convex curvature facing towards the front surface  12 . The latter curve has its mirror-opposite in a convex-curved terminal segment of a thin linear cut  26 . The pair of opposite convex-curved segments delineate a thinned-down domain  27 . Continuing after the convex-curved segment that delimits the thinned-down domain  27 , the thin linear cut  26  runs for a stretch in the direction towards the front surface  12 , then turns towards the top surface  10  and finally terminates in a bore hole  28  at the thin linear cut  22 . The bore hole  28  serves to insert and remove a spark erosion wire that is used to produce all of the thin linear cuts of the material block  4 . 
     The thin linear cuts  15 ,  18 ,  20 ,  22 ,  23  and  26  constitute narrow material-free gaps across the material block  4  by which different material domains are delimited. Thus, the thin linear cut  15  and the front surface  12  of the L-leg  6  (after removal of the material portions  17 ,  17 ′) delimit a material portion serving as coupling member  29 . The thinned-down domains  16 ,  19  acting as flexural pivots allow the coupling member  29  to flex elastically in a parallel plane to the lateral boundary surfaces  7 ,  8 . The thinned-down domain  19  connects the coupling member  29  to a material portion that is delimited between the thin linear cut  22  and the top surface  10  of the L-leg  5  and serves as lever  30 . The (virtual) fulcrum axis of this lever is represented by the thinned-down domain  21 . At the opposite lever end from the thinned-down domain  19 , i.e., in the area of the thinned-down domain  24 , the lever  30  is connected to the material portion that forms a further coupling member  31  delimited by the thin linear cuts  22  and  23  between the thinned-down domains  24  and  25 . 
     A further lever  32  is formed by the material portion that is bounded by the segment of the thin linear cut  23  extending from the thinned-down domain  25  to the thinned-down domain  27 , the thin linear cut  26 , and the segment of the thin linear cut  22  extending from the bore hole  28  to the thinned-down domain  24 . Apart from the levers  30 ,  32 , a material portion  33  for anchoring the device on the base plate  2  is formed by the portion of the L-leg  5  between the levers  30 ,  32  and the bottom surface  9  and by the portion of the L-leg  6  between the coupling member  29  and the rear surface  13 . 
     All of the thinned-down domains  16 ,  19 ,  21 ,  24 ,  25  and  27  represent flexural pivots by which virtual pivotal axes are defined for the relative rotational displacement between the material portions that hang together through the respective thinned-down domains. The spatial configuration is purposely arranged so that the pivotal points defined by the thinned-down domains  19 ,  21  and  24  are located on a straight line, meaning that the force-introduction points defined by the virtual pivotal axes of the thinned-down domain  19  and  24  are lined up in a straight line with the virtual pivotal axis defined by the thinned-down domain  21 . 
     In the embodiment of FIG. 3, the bottom surface  9  (see FIG. 2) of the material portion  33  that is anchored on the base plate  2  serves as contact surface for the form-fitting engagement with the surface area of the base plate  2  that faces towards the material block  4 . For the centered attachment of the material block  4  in relation to the two side plates  3 , mounting parts  34  extend parallel to the two lateral boundary surfaces  7 ,  8  of the material block  4  (FIG.  2 ). The mounting parts  34  are connected to the base plate  2 , standing off perpendicularly from it. The mounting parts  34  and the lateral boundary surfaces  7 ,  8  facing towards them are spaced apart by space holders (not shown). In the area of the space holders, the anchored material portion  33  has two bore holes  35  running perpendicular to the lateral boundary surfaces  7 ,  8  (FIG.  2 ). The material block  4  is fastened to the base plate  2  by two screw bolts  36 , passing through the bore holes  35  and matching holes in the mounting parts  34 . 
     Instead of the arrangement of FIG. 3 for mounting the material block  4  of FIG. 2 on the base plate  2  of the weighing cell, an alternative mounting arrangement is shown in FIGS. 4 and 5. The material block of FIG. 4 corresponds entirely to the material block  4  of FIG. 2 with respect to the shape of the material block and the way in which the material portions forming the levers  30 ,  32  and the coupling members  29 ,  31  are delimited by the thin linear cuts  15 ,  18 ,  20 ,  22 ,  23  and  26 . Therefore, the corresponding parts in FIG. 4 have the same reference numbers as in FIG.  2 . With respect to these reference numbers, the description given for FIG. 2 also serves as reference for FIG.  4 . 
     The only difference is in the way the material block  4  is fastened to the base plate  2 . Still in agreement with FIG. 2, the embodiment of FIG. 4 has the same configuration of the coupling member  29  as in FIG.  2 . The configuration is also identical with regard to the adjacent portion of the L-leg  6  where two recesses  37 ,  37 ′ extend symmetrically (in relation to the parallel mid-plane between the two lateral boundary planes  7 ,  8  of the material block  4 ) from the front surface  12  in the direction towards the rear surface  13  of the leg  6 . The recesses  37 ,  37 ′ delineate in the coupling member  29  a narrow web segment  38  extending in the mid-plane and providing the coupling member with an elastic flexibility allowing it to bend transversely in relation to the mid-plane. In contrast to FIG. 2, the arrangement of FIG. 4 has bore holes  40  running parallel to the lengthwise direction of the leg  5  through the material portions between the rear surface  13  and the end surfaces  39 ,  39 ′ of the recesses  37 ,  37 ′ on each side of the narrow web segment  38 , while at the same time the arrangement of FIG. 4 lacks the bore holes  35  of the embodiment of FIG.  2 . 
     As illustrated in FIG. 5, the bottom surface  9  of the L-leg  5  and an adjacent part of the rear surface  13  of the L-leg  6  serve as a form-fitting contact interface with a surface area of the base plate  2 , which extends parallel to the main plane of the latter, and also with a transverse end surface area  41  of the base plate  2 . The material portion  33  of the material block  4  is firmly attached to the base plate  2  by means of two screw bolts  42  that pass through holes  40  extending parallel to the plane of the base plate  2  and are screwed into tapped holes in the base plate  2 . 
     A further alternative for attaching the material block  4  to the base plate  2  is shown in FIGS. 6 and 7. The material block  4  shown in FIG. 6 corresponds fully to the material block  4  of FIGS. 2 and 4 with respect to the shape of the material block and the way in which the levers  30 ,  32  and the coupling members  29 ,  31  are delineated by the thin linear cuts  15 ,  18 ,  20 ,  22 ,  23  and  26 . The congruence of the embodiments also extends to the recesses  37 ,  37 ′ by which the narrow web segment  38  of the coupling member  29  is formed. The corresponding parts in FIG. 6 have the same reference numbers as in FIGS. 2 and 4; and with respect to the shared reference numbers, the description given for FIGS. 2 and 4 also serves as reference for FIG.  6 . 
     The material block  4  as illustrated in FIG. 6 is distinguished from FIGS. 2 and 4 by the absence of the bore holes  35  and  40 , respectively. Instead, the L-leg  5  of the material block  4  is traversed by two bore holes  43  extending between its bottom surface  9  and top surface  10 . The bore holes  43  have shoulders  44  formed by a step from a smaller diameter (in the material portion  33  attached to the base plate  2 ) to a larger diameter opening towards the top surface  10 . 
     FIG. 7 presents a top view of the base plate  2  and the top surface  10  of the monolithic material block  4  that is mounted on it, illustrating that the bottom surface  9  of the L-leg  5  serves as contact surface for a form-fitting engagement with a surface area of the base plate  2  in the middle between the two side plates  3 . Also shown are the heads of two screw bolts  45  that engage the shoulders  44 , traverse the material portion of the L-leg  5  between the shoulders  44  and the bottom surface  9 , and are screwed into the tapped holes  46  of the base plate  2  (FIG.  1 ), whereby the material portion  33  is firmly attached to the base plate  2 . 
     Except for the aforementioned differences in the way the material block  4  is fastened to the base plate  2 , the design of the rest of the weighing cell as illustrated in FIGS. 1,  3  and  5  is identical for the three attachment configurations described above. According to those drawing figures, two rigid, plate-shaped parallelogram guides  47 ,  48  extend on either side of and parallel to the plane of the base plate  2 . Each of the parallelogram guides  47 ,  48  consists of a rigid plate-shaped part whose lengthwise direction is parallel to the side plates  3 . Attached to the border areas  49 ,  50  that run across the width of the parallelogram guides  47 ,  48  are the attachment terminals  51  of two flexural pivots  52  at each transverse border area of each plate. Those of the flexures  52  that have terminals  51  connected to the border areas  50  of parallelogram guides  47 ,  48  have opposite attachment terminals  51 ′ aligned with and fastened to border surface areas  53  of the side plates  3 . The border surfaces  53  are parallel to the planes of the parallelogram guides  47 ,  48 . In this arrangement, the border surface areas  53  are slightly raised in the attachment area in comparison to the rest of the same border surfaces to provide~ clear space for a deflection of the parallelogram guides  47 ,  48  in relation to the rotational axes formed by the virtual pivotal axes of the flexural pivots  52  that run parallel to the planes of the parallelogram guides. However, the slightly raised configuration of the attachment areas is not shown in FIGS. 1,  3 ,  5  and  7 . 
     From where they are connected through their attachment terminals  51 ′ to the side plates  3 , the parallelogram guides  47 ,  48  extend in their lengthwise direction to a load receiver  54  that is arranged next to the front surface  12  of the material block  4 . The load receiver  54  is connected to attachment terminals  51 ″ of the flexural pivots  52  that are at their opposite attachment terminals connected to the border areas  49  of each of the parallelogram guides  47 ,  48 . In this manner, the parallelogram guides  47 ,  48  in their attached condition to the side plates  3  and together with the load receiver  54  constitute a parallelogram guide mechanism in which the parallelogram plane is defined by the lengthwise direction of the parallelogram guides  47 ,  48  and the displacement travel direction of the load receiver  54 . 
     As can be seen in FIGS. 3 and 5, the side of the load receiver  54  that faces towards the front surface  12  of the material block  4  has a slightly raised surface area  55  where the load receiver meets the coupling member  29  along a surface area bounded by the flexural pivot  16  on one side and the bottom surface on the other and where the load receiver  54  is attached to the coupling member  29  by means of screw bolts that are anchored in tapped holes  56  of the coupling member  29  (FIG. 2,  4  and  6 ). 
     As can further be seen in the partially sectional side view of the weighing cell in FIG.  3  and the top view in FIG. 7 (in which the parallelogram guide  47  is removed), a U-shaped lever extension  57  embraces the further lever  32  (which is formed in the material block  4 ) with two U-legs  59 ,  60  that are attached by two screw bolts  62  passing through two bore holes  61  of the further lever  32  (FIGS. 2,  4  and  6 ) and interposed space holders  58 . The U-legs  59 ,  60  extend parallel to the planes of the base plate  2  and parallelogram guides  47 ,  48  in the direction towards the end portion of the stationary part  1  farthest from the load receiver  54 , where the electromagnetic force-compensation system  63  (used as measuring transducer) is installed. To accommodate the measuring transducer, a recess  64  (FIG. 1) is formed in the respective part of the base plate, where one leg  66  of a magnet yoke  69  enclosing two plate-shaped permanent magnets  67 ,  68  is attached to the end surface  65  of the recess that runs transverse to the planes of the parallelogram and the base plate. 
     A compensation coil  71 , held by the U-bottom  70  (of the lever extension  57 ) that connects the U-legs  59 ,  60  inside the magnet yoke  69 , is immersed in the air gap between the two permanent magnets  67 ,  68 . Also attached to the U-bottom  70  is a position sensor vane  72  that reaches into the position sensor gap  73  of a light gate sensor  74 . 
     In the embodiments of FIGS. 1 through 7 as described above, the force to be measured is introduced into the load receiver  54  in the direction in which the parallelogram mechanism allows the load receiver to be deflected. As an example for introducing the force in this manner, a weighing pan carrier (not shown) may be arranged immediately on the load receiver. However, there are also other ways of coupling the load receiver  54  to the force to be measured. The levers  30 ,  32  of the material block  4  that are coupled to the load receiver  54  and the lever extension  57  reduce the force to be measured. A compensation current flowing through the compensation coil  71  is regulated by the position sensor signal of the position sensor  74  in such a manner that the compensating force that results from the interaction between the compensation coil  71  and the magnetic field of the permanent magnets  67 ,  68  is in equilibrium with the force to be measured that has been applied to the load receiver  54 . Thus, the magnitude of the compensating current represents a measure for the magnitude of the force that is to be measured. 
     In the embodiments of FIGS. 1 through 7 as described above, the two force-transmitting levers with the flexural domains  21 ,  27  forming the lever fulcrums and the coupling members  29 ,  31  are formed by appropriately shaped material portions of the monolithic material block  4  and supported on the base plate  2  by the stationary material portion  33  of the material block  4 . In contrast to this arrangement, the embodiments of FIGS. 8 through 10 are distinguished by a different configuration of the device that transmits the force from the load receiver to the measuring transducer. Except for the difference in the force-transmitting device, the design of the embodiments of FIGS. 8 through 10 corresponds with the concept illustrated in FIGS. 1,  3 ,  5  and  7  with respect to all relevant parts, in particular the stationary part  1  and the parallelogram guides  47 ,  48  that are connected to it. Therefore, the corresponding parts in FIGS. 8 through 10 have the same reference numbers as in FIGS. 1,  3 ,  5  and  7 . With respect to these reference numbers, the foregoing description also covers FIGS. 8 through 10. 
     Deviating from the embodiments of FIGS. 1 through 7, the lever  75  in the embodiments of FIGS. 8 through 10 is formed as a separate component. Near the end that is next to the load receiver  54 , the lever  75  has a pivotal portion  76  transverse to the parallelogram plane and extending from a recess  77  in one side plate  3  that is open towards the load receiver  54  to a corresponding recess  77  that is formed in the other side plate  3 . The front side  78  of the pivotal portion  76  that faces towards the load receiver  54  is aligned with frontal end surfaces  79  of the side plates  3  adjacent to the recesses  77 . Each of the frontal end surfaces  79  serves as attachment surface for an attachment terminal  80  of a flexural pivot  81 , whose opposite attachment terminal  82  is attached to the front side  78  of the end of the pivotal portion  76  that reaches into the recess  77 . The virtual pivotal axes of the two flexural pivots  81  lie on a straight line that extends transverse to the parallelogram plane and represents the virtual fulcrum axis of the lever  75 . 
     At a location half-way between the two side plates  3 , the pivotal portion  76  of the lever  75  has a short lever arm  83  projecting beyond the plane of the flexural pivot  81  towards the load receiver  54 . Through an attached coupling member  84 , the short lever arm  83  is connected to a raised attachment area  85  of the load receiver  54 . The coupling member is configured as a separate part with a rigid lengthwise portion parallel to the direction of the load receiver  54  extending between two virtual pivotal axes  86 . Outside of the virtual pivotal axes  86 , the coupling member  84  has terminal portions that are attached to the lever arm  83  and to the raised attachment area  85 , respectively. 
     On the other side of the pivotal portion  76 , opposite from the lever arm  83  in relation to the plane of the flexural pivots  81 , a U-shaped lever extension  87 , similar to the lever extension  57  of FIG. 7, is attached with screw bolts  88 . The U-legs  89  of the lever extension  87  reach to the force compensation system  63  whose principal make-up has been described above in the context of FIG.  7 . Compared to FIG. 7, the only difference is that the position sensor  74  is arranged on the side of the magnet yoke  69  that faces away from the load receiver  54 , and the arrangement of the position sensor vane  72  on the U-bottom  90  is configured accordingly. 
     In the embodiment of FIGS. 8 and 9, the pivotal portion  76  lies behind the load receiver  54 , as viewed in the direction from the attachment terminals  51 ″ at the load-receiver end of the parallelogram guides  47 ,  48  to the attachment terminals  51 ′ at the stationary part. Compared to FIGS. 8 and 9, the only difference in the embodiment of FIG. 10 is that (in relation to the same viewing direction) the pivotal portion  76  is arranged in front of the load receiver  54 , whose raised attachment area  85  reaches around the pivotal portion  76  and projects out to the plane of the coupling member  84 . With regard to those parts in FIG. 10 that are analogous to all other embodiments, the previously used reference numbers and the description for said parts also apply to FIG.  10 . 
     As illustrated in the FIGS. 1,  5 ,  8 ,  9  and  10 , the side plates  3  in all of the embodiments of the weighing cell have a continuous slit  91  starting in the vicinity of the attachment terminal  51 ′ of the upper parallelogram guide  47  (in accordance with the orientation of the drawing) and running parallel to the plane of the parallelogram guides. At one end, the slit  91  is angled up so that it approaches the border surface area  53  that carries the attachment terminal  51 ′ whereby a narrow material connection  92  is formed. At the opposite end  93 , the slit  91  is open to the outside. In the embodiments of FIGS. 1 through 5, the open end  93  terminates at the frontal border surface  94  of the side plate  3 . The frontal border surface  94  runs transverse to the plane of the base plate  2  and to the parallelogram plane. In contrast, in the embodiments of FIGS. 8,  9  and  10 , the open end of the slit  93  terminates at the border surface area  53  that runs parallel to the plane of the base plate  2 . 
     An adjustment screw  95  (FIGS. 5,  8  and  9 ) that crosses the slit  91  near its open end  93  allows the adjustment of the width of the slit perpendicular to the parallelogram guides  47 ,  48 , with the narrow material connection  92  functioning as a flexural pivot. The adjustment screw  95  works against an elastic element  96 , e.g., a helix spring as in FIG. 5 or a leaf spring as in FIGS. 8 and 9, that has the function of pushing the slit  91  apart. By varying the width of the slit, the corner points of the parallelogram guide mechanism can be precisely adjusted. 
     In all of the illustrated configurations, the force that is introduced into the load receiver  54  for the purpose of being measured is directed from top to bottom. As shown in FIG. 3, a support  98  is attached by screw bolts  99  to the downward-facing surface  97  of the base plate  2 . The bore holes  100  for inserting the screw bolts  99  in the base plate  2  can also be seen in FIGS. 1 and 7. 
     To describe the arrangement in more detail, the support  98  has a transverse part  101 , reaching from one side plate  3  to the other, in which the screw bolts  99  are anchored. Halfway between the side plates  3 , the transverse part  101 , which comes close to the lower parallelogram guide  48 , has a column  102  directed perpendicularly to the planes of the base plate and the parallelogram guides  47 ,  48  and projecting downwards to pass with lateral clearance through an opening in the lower parallelogram guide  48 . The projecting portion of the column  102  serves to mount the weighing cell, for example on the chassis plate of a balance housing. In order to maintain the advantages of a symmetric configuration, the upper parallelogram guide  47  has an opening  103  (FIGS. 5,  8  and  10 ) in the place where the lower parallelogram guide  48  has the opening  104  for the passage of the column  102 . The opening  104  of the lower parallelogram guide  48  for the passage of the column  102  is partially visible in FIG.  5 . 
     Major portions of the embodiments of FIGS. 11 a  and  11   b  share the same principal configuration and are therefore referenced with the same numbers in the following description. Both embodiments are made from a hollow-profile section  200  with a rectangular outside cross-section that is cut from a length of extruded profile stock. The interior space of the hollow-profile section  200 , likewise of rectangular cross-section, is divided by an interior transverse wall  201  into two rectangular corridors  202 ,  203 . The latter are enclosed by two side walls  204 ,  205  as well as upper and lower transverse walls  206 ,  207 . The side walls  204 ,  205  are integrally connected to the interior transverse wall  201  and perpendicular to it. The exterior transverse walls  206 ,  207  run parallel to the plane of the interior transverse wall  201  and are integrally connected to the borders of the side walls  204 ,  205 . Thus, the smaller corridor  202  is enclosed by the interior transverse wall  201 , the portions of the side walls  204 ,  205  that extend towards the lower transverse wall  206 , and the lower transverse wall  206  itself, while the larger corridor  203  is enclosed by the interior transverse wall  201 , the portions of the side walls  204 ,  205  that extend towards the upper transverse wall  207 , and the upper transverse wall  207  itself. 
     The embodiment shown in FIG. 11 a  has two continuous lengthwise slits  208 ,  209  in the upper transverse wall  207  (in the orientation of FIG. 11 a ) that extend in lengthwise direction (perpendicular to the rectangular cross-section) of the hollow-profile section  200 . The lengthwise slits  208 ,  209  in FIG. 11 a  are spaced at such a distance from the respectively adjacent side wall  204 ,  205  that the respective border  210 ,  211  of each slit that is nearest to the side wall runs flush with the interior surface of that side wall  204 ,  205 . The lengthwise slits  208 ,  209  between themselves delineate an upper parallelogram guide  212  (in the orientation of FIG. 11 a ). 
     At a distance from the front and rear edges  213 ,  214  of the hollow-profile section  200 , at each pair of end portions of the lengthwise slits  208 ,  209 , there is a pair of transverse grooves formed in the hollow-profile section  200 . Clearly visible in FIG. 11 a  are the pairs of grooves  215 ,  216  formed at the outer surface of the upper parallelogram guide  212 . The grooves  215 ,  216  have a convex-curved profile (in a parallel section to the parallelogram plane) and extend across the width of the parallelogram guide  212  between the lengthwise slits  208 ,  209  as well as across the portions of the side walls  204 ,  205  that run flush with the slits. Opposite the grooves  215 ,  216  that are formed from the outside, analogous pairs of grooves  217 ,  218  are formed from the inside of the parallelogram guide  212 . The two pairs of grooves  215 ,  217  and  216 ,  218  each delimit a thinned-down domain  219 ,  220  that serves as a flexural pivot for the displacement of the parallelogram guide  212 . 
     To adjust the flexural stiffness of the thinned-down domain  219 ,  220 , the upper parallelogram guide  212  has openings  221 ,  222  formed in the areas of the two pairs of grooves  215 ,  217  and  216 ,  218 , respectively. The openings  221 ,  222  cut completely through the respective ends of the parallelogram guide  212 , transverse to the plane of the latter. Together with the lengthwise slits,  208 ,  209 , the openings  221 ,  222  determine the length of the thinned-down domains  219 ,  220  transverse to the lengthwise direction of the parallelogram guide  212 . 
     In the invisible area (in FIG.    11 a ) of the lower transverse wall  206  and adjacent areas of the two side walls  204 ,  205 , there are lengthwise slits, grooves, thinned-down domains and openings analogous to the lengthwise slits  208 ,  209 , grooves  215 ,  216 ,  217 ,  218 , thinned-down domains  219 ,  220 , and openings  221 ,  222  so that a lower parallelogram guide, analogous to the upper parallelogram guide  212 , is formed in that area. In this regard, FIG. 11 a  shows only the recesses  223 ,  226  in the side wall  204  that are in line with the grooves that delimit the thinned-down domains of the lower parallelogram guide. 
     A transverse slit  227  extends perpendicular to the lengthwise direction across the side wall  204  from the recess that aligns with the groove  215  all the way to the corresponding recess  223  of the side wall  204  (that aligns with the corresponding groove of the lower parallelogram guide). An analogous transverse slit  228 , cutting through the side wall  205  opposite the side wall  204 , is aligned with the transverse slit  227  in a transverse plane in relation to the lengthwise direction the parallelogram guides. Further, the interior transverse wall  201  is perforated by a transverse slit  229  connecting the transverse slits  227 ,  228 . In this manner, the transverse slits  227 ,  228 , and  229  delineate the load receiver  230  against the stationary part  231 . Accordingly, the load receiver  230  comprises the portions of the side walls  204 ,  205  and transverse walls  206 ,  207  that are bounded on one side by the frontal edge  213  and on the other side by the transverse slits  227 ,  228  and by the thinned-down domains (adjacent to the slits  227 ,  228 ) of the upper and lower parallelogram guides, while the stationary part  231  comprises the portions of the side walls  204 ,  205  that are bounded on one side by the rear edge  214  and on the other side by the transverse slits  227 ,  228 , and also the portions of the transverse walls  206 ,  207  that are bounded on one side by the rear edge  214  and on the other side by the thinned-down domains  220  at the far end (in relation to the load receiver  230 ) of the parallelogram guides. 
     Compared to FIG. 11 a , the only relevant difference in FIG. 11 b  is in the arrangement of the lengthwise slits with corresponding changes in the transverse slits. As seen in FIG. 11 b , the lengthwise slits delimiting the two parallelogram guides  212 ′ are formed in the side walls  204 ,  205 , of which only the lengthwise slits  208 ′ in the side wall  204  are visible in FIG. 11 b , while the symmetrically aligned lengthwise slits in the side wall  205  are invisible in FIG. 11 b . The borders  210 ′ of the lengthwise slits  208 ′ that are closest to the respectively adjacent parallelogram guides  212 ′ are running flush with the inner surfaces of the transverse walls  206 ,  207 . 
     Further, as a minor deviation from FIG. 11 a , the pairs of grooves  215 ′,  217 ′ and  216 ′,  218 ′ that delimit the thinned-down domains  219 ′,  220 ′ do not have a semi-circular cross-section perpendicular to the plane of the parallelogram guides  212 ′ but are elongated instead in the longitudinal direction. As in the embodiment of FIG. 11 a , the length of the thinned-down domains  219 ′,  220 ′, measured transverse to the lengthwise direction, is delimited by openings  221 ′,  222 ′ in the two parallelogram guides  212 ′. 
     The transverse slits  227 ′,  228 ′ that delimit the load receiver  230  against the stationary part  231  extend between the grooves  217 ′ that face towards the inner surfaces of the parallelogram guides and delineate the sides of the thinned-down domains  219 ′ that face each other. As in FIG. 11 a , the continuous transverse slit  229 ′ of the interior transverse wall  201  connects the two transverse slits  227 ′ and  228 ′. 
     As can be seen in FIGS. 11 a  and  11   b , the front surface of the load receiver  230  that is enclosed by the frontal edge  213  has attachment holes for mounting a weighing pan carrier. The force to be measured by the apparatus in FIGS. 11 a  and  11   b  is directed top to bottom, so that the effect of a load is to deflect the load receiver downwards. This is why the side walls  204 ,  205  are extended in the area of the stationary part so that they reach beyond the outside surface  232  of the lower transverse wall  206  that faces in the direction of the deflective displacement. In the embodiment of FIG. 11 a , the extended side wall portions  233  extend from the rear edge  214  (farthest from the load receiver  230 ) to the transverse slits  227 ,  228  that separate the load receiver  230  from the stationary part  231 . In the embodiment of FIG. 11 b , on the other hand, the extended side wall portions  233 ′ extend from the rear edge  214  (farthest from the load receiver  230 ) to the nearest groove  216 ′ that delineates the thinned-down domain  220 ′ at the end of the parallelogram guide  212 ′ that is near the rear edge  214 . Thus, when the hollow-profile section  200  with the extended side wall portions  233  (or  233 ′, in FIG. 11 b ) is mounted on a chassis plate that is parallel to the plane of the parallelogram guides  212  (or  212 ′), there will be a clearance gap between the chassis plate and the facing surfaces of the load receiver  230  and lower parallelogram guide  212  ( 212 ′), allowing the load receiver and parallelogram guide to deflect downwards under a load. 
     In both embodiments, the portion  234  of the interior transverse wall  201  between the rear edge  214  and the transverse slit  229  ( 229 ′) serves as the base plate for mounting the force-transmitting device that contains the one or more levers. The portion  235  of the interior transverse wall  201  from the transverse slit  229  ( 229 ′) to the front edge  213  is available for attaching a coupling member connected to the lever of the force-transmitting device, so that the load receiver  230  is coupled to the lever and the deflection of the load receiver under a load is transmitted to the lever. 
     In contrast to all of the embodiments described up to this point, the embodiment of FIG. 12 is based on an essentially rectangular monolithic material block  300  whose largest pair of surfaces  301  extend parallel to the parallelogram plane of the guide mechanism. The cross-section of the material block  300  transverse to the parallelogram plane has the shape of an H-profile as can be seen in FIG. 12, particularly by looking at the end surface  302  that runs transverse to and connects the largest pair of surfaces  301  that are parallel to the parallelogram plane. Accordingly, the material width of the material block  300  perpendicular to the parallelogram plane is greater at the two flanges  303 ,  304  than at the connecting web  305  of the H-profile. 
     A thin linear cut  306  traversing the upper H-flange  303  in FIG. 12 forms a material-free space delimiting within the material block  300  an upper parallelogram guide  307  that is bounded on the opposite side from the thin linear cut  306  by the top surface  308  running transverse to both the largest surface  301  and the end surface  302 . Opposite the terminal portions of the thin linear cut  306 , the top surface  308  has recesses  309 ,  310  that are curved towards the interior of the block and have their symmetric mirror-images in the opposing curves of the terminal portions of the thin linear cut  306 . Thus, the curved recesses  309 ,  310 , together with their counterparts in the terminal portions of the thin linear cut  306 , are delineating thinned-down domains  311 ,  312  that serve as flexural pivots of the upper parallelogram guide  307 . 
     In the same manner, a lower parallelogram guide  319  between flexural pivots  317 ,  318  is delineated in the lower H-flange  304  in FIG. 12 by two recesses  313 ,  314  in the bottom surface  315  of the block that are mirror images of the curved recesses  309 ,  310  and by a thin linear cut  316  that is the mirror image of the thin linear cut  306 . 
     Starting from its left terminal portion (in the arrangement of FIG.  12 ), the thin linear cut  306  turns and then runs transverse to the lengthwise direction of the parallelogram guides  307 ,  319  in a continuing section  320  that ends at some distance from the lower parallelogram guide  319  and has two detours curved towards the inside of the material block  300  and located at an interval from each other. A thin linear cut section  321  branches off from the left-side terminal portion (in the arrangement of FIG. 12) of the thin linear cut  316  delineating the lower parallelogram guide  319  and then runs next to and forms mirror-images of the curved detours of the continuing linear cut section  320 . Thus, the mirror-symmetric curves of the continuing section  320  and the linear cut section  321  delineate thin flexural domains  322 ,  323  between each other, so that a coupling member  324  extending transverse to the lengthwise direction to the parallelogram guides  307 ,  319  is formed between the thin flexural domains  322 ,  323 . 
     The foregoing arrangement of the continuing linear cut section  320  and the portion of the thin linear cut section  321  from the lower flexural domain  323  of the coupling member  324  to the flexural pivot  317  of the lower parallelogram guide  319  delimits the load receiver  325  that hangs together with the coupling member  324  through the thin flexural domain  323 . 
     On the far side from the load receiver  325 , the thin linear cut section  321 , together with the portion of the continuing section  320  from the upper flexural domain  322  of the coupling member  324  to the flexural pivot  311  of the upper parallelogram guide  307 , delimits a lever  326  that hangs together with the coupling member  324  through the thin flexural domain  322 . 
     The lever  326  is delimited against the lower parallelogram guide  319  by the linear cut  316 . Beyond the terminal portion next to the flexural pivot  318  at the far end from the load receiver  325 , the linear cut continues transverse to the lengthwise direction of the parallelogram guides  307 ,  319  and ends approximately halfway into the H-web  305 , so that the continuing section  327  delimits a coupling portion  328  of the lever  326 . The coupling portion  328  of the lever  326  connects through a further coupling member  329 , likewise delimited by thin linear cuts and equipped with flexural pivots at both ends, to a further Lever  330  that follows the lever  326  in the lever-reduction chain. The further lever  330  is separated from the lever  326  by a thin linear cut  331  located within the web portion  305  of the H-profile. 
     At its far end from the coupling portion  328 , the further lever  330  is connected through a coupling member  332  to the output lever  333  of the force-transmitting device that is constituted by the arrangement of levers and coupling members. Like the lever  326  and its coupling member  324 , the other coupling members and levers are bounded by thin linear cuts. The same is true for the flexural domains  334 ,  335  and  336  that form the fulcrums of these levers. The entire arrangement of thin linear cuts is clearly represented in FIG.  12 . 
     The flexural domains  334 ,  335  and  336  that serve as lever fulcrums are formed out of the stationary supporting part  337  of the material block  300 . On the opposite side from where the levers  326 ,  330  and  333  are arranged, the supporting part  337  is delimited against the upper parallelogram guide  307  by the thin linear cut  306 . 
     Also shown in FIG. 12 is an interior parallelogram-guided portion  338  of the material block  300  that is coupled to the further lever  330  and serves to couple a calibration weight to the force-transmitting device as discussed in detail in the earlier patent application P 196 05 087. Bore holes  339  formed in the output lever  333  are provided for the attachment of the legs of a lever extension that extend to an electromagnetic force-compensation system mounted on a console  340  of the stationary part in accordance with the same general concept that is also represented in FIG.  7 .