Abstract:
The stand free multi-beamed load cell for accurately monitoring and registering weight changes has at multiple beams secured to one another to form a polygon rim with an open center. Multiple tabs are equally spaced from one another along the rim to receive securing members to secure the rim to a support surface. Each tab has a pair of balancing members on either side of the securing member to maintain the rim above the support surface. At least one of the beams has a bridge to reduce the depth of the beam to enable flexing under application of the weight. A strain gage proximate the bridge registers the flexing of the beams, sending the signals through an electronic connector to a control means. The balance members serve to minimize the deflection on the rim approximate the tabs, creating maximum strain level at the bridge. The tabs and balance members further serve to accommodate for any variations in the support surface.

Description:
CROSS REFERENCE TO PRIOR APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application 08/592,865 filed Jan. 24, 1996, now U.S. Pat. No. 5,752,498, which is a continuation-in-part of U.S. Ser. No. 08/319,935 filed Oct. 7, 1994 now U.S. Pat. No. 5,546,926 which are incorporated herein recited in full. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to stand free multi-beamed load cells. 
     2. Brief Description of the Prior Art 
     As stated in Strain Gage Based Transducers, 1988 by Measurements Group, Inc., which is incorporated herein as though recited in full, for certain types of applications, the characteristics of the straight cantilever beam can be improved upon. The improvement can be by designs which induce “multiple bending” (reversed curvature) in the beam element. The potential advantages of a beam which is built-in at both ends, and loaded at the center include; intrinsic stiffness and straining line motion of the point of load application as the beam deflects. The spring element also lends itself to relatively easy installation of a full bridge strain gage circuit on the upper surface of the beam. Some degree of non linearity in output can be expected, however, because of the membrane stress produced in the beam (as it deflects) by the rigidly spaced end supports. Additionally, as for most flexural spring elements, it is necessary to vary the section modulus of the beam along its length if the strain gages are to lie in nearly uniform strain fields. 
     An alternative configuration, a spring element has generally the same bending moment distribution and deflection pattern and retains essentially the same advantages except that the compliance is twice as great if the dimensions are otherwise the same. Because the end restraints are free to move laterally as the upper and lower beams deflect, the membrane stress is eliminated. Any such motion, however, represents a small change in the moment arm of the applied load, which can manifest itself in the form of non-linear response if the ration of the deflection to the beam length is great enough. 
     Pairs of strain gages are mounted side-by-side on one surface of the beam, or back-to-back on opposite surfaces, to implement a full bridge circuit. The design is sensitive to both the location and direction of the applied load. To function properly, the design must incorporate features to assure that loading can occur only along the intended axis. 
     A significantly improved form, where the load sensing is accomplished with two beams, joined by relatively massive sections at both ends. With this configuration, externally applied couples are counteracted by axial forces in the sensing beams, minimizing the effects of off-axis loads. One of the drawbacks of the design is its excessive compliance. The deflection which takes place in the beam segments between gage locations not only increases the compliance of the unit, but also degrades the linearity. Better load cell performance can be obtained by either shortening the beams or increasing the beam thickness between gage sites. Such design changes should be made with full consideration of the shear load which must be borne by the element. Strain gage installation and inspection are more difficult when gages are located inside of a hole. 
     Various forms of the coupled dual-beam arrangement are widely used in load cells for weighing applications. 
     Another type of bending spring element is the ring. The ring shaped element also has a long, classical history in measurement technology, stemming from the well known Morehouse proving ring, once universally used to calibrate materials testing machines. Although ring type spring elements always involve bending, direct stress is also intrinsic to the configuration, and the combination of the resulting two deformation modes provide the primary distinction from pure beams. 
     In a basic ring design, the strain distribution in the ring is a complex function of the geometry, and is significantly affected by the design details of the bosses. The bending moment does not vary significantly in the region of the horizontal diameter, the strain distribution is nearly uniform in this area. 
     The squared ring is easier, less costly to fabricate, decreases the compliance of the spring element, and correspondingly improves the linearity. At the same time, the flexural stiffness at the junctures of the bosses and the ring has been reduced to minimize the sensitivity of the element to off axis load components. There are countless other designs based on the presence of a stress concentrating hole and/or lateral notches in an axially loaded member. A representative configuration, taken from U.S. Pat. No. 3,315,203. 
     In adapting the ring concept to different load cell specifications for capacity, physical size, etc., the designs sometimes deviate so far from a conventional ring in appearance that their classification as such becomes arguable. 
     The evolution of beam type load cells has been traced from the basic cantilever beam, through a number of refinements, to a variety of more sophisticated forms with generally superior properties. Multiple beam spring elements are currently very popular, and can be found in many commercial transducers, particularly in low capacity units. It is the need for this last qualifier which leads to the subject matter of the present section. 
     Although multiple beam designs have good overall characteristics, including linearity and insensitivity to point of load application, they do not lend themselves well to being scaled up for higher load cell capacities. As the capacity of the load cell rises, so does the size of the spring element, along with its mass and, usually, its deflection at rated load. Because of these considerations, spring elements based on the measurement of bending strains are not commonly used in load cells with capacities greater than about 1000 lb. Instead, transducer designers ordinarily turn to one of two other configurations, the shear web or column, to achieve very high capacities in compact, low compliance spring elements. 
     One of the advantages of the shear web spring elements is its low sensitivity to variations in the point of load application. Static equilibrium considerations decree that the vertical shear force on every section of the beam to the right of the load be the same, and exactly equal to the applied load. Thus the shear in the web should be independent of the point of load application (along the beam centerline), as long as the load is applied to the left of the web. If the strain gages sensed only the shear induced strains, the bridge output would be unaffected by the position of the load or by other bending moments in the vertical plane. 
     Since the gage grids are necessarily finite in length, however, and thus span a small distance above and below the neutral axis, their outputs are also slightly affected by the bending strains in the web. With the grids centered on the neutral axis, the tensile and compressive bending strains above and below the axis tend to be self canceling in each grid. But the cancellation is usually less than perfect because of small asymmetries in the spring element and strain gage installation. 
     Because of higher order effects tending to couple the shear and bending strains, it is always preferable to design the beam for the lowest practicable bending moment in the shear web. This would seem to suggest the use of very short beams, but the point of load application must be far enough away from the shear web so that the web behavior approximates the ideal described here. The bending moment at the center of the web is zero, and for a given beam length and rated capacity, the bending moment throughout the beam is halved. 
     Another type of shear web spring element consists of a metal block in which holes or slots have been machined to form webs subjected to direct shear under axial load. A further example is where the shear webs are produced by drilling a hole longitudinally through the beam. Strain gages oriented at +−45 degrees to the beam axis are then installed inside the hole to sense the shear force, as in U.S. Pat. No. 4,283,941. 
     SUMMARY OF THE INVENTION 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The advantages of the instant disclosure will become more apparent when read with the specification and the drawings, wherein: 
     FIG. 1 is a top view of one embodiment of the free standing elliptical beam load cell. 
     FIG. 2 is a front view of the free standing elliptical beam load cell and strain gage of FIG. 1; 
     FIG. 3 is a cross section view of the free standing elliptical beam load cell, arch bridges and strain gages; 
     FIG. 4 is a cutaway side view of the mounting portion of the free standing elliptical beam load cell of FIG. 1; 
     FIG. 5 is a cutaway front view of the mounting portion free standing elliptical beam load cell; 
     FIG. 6 is a top view of the free standing elliptical beam load with a vessel installed on it; 
     FIG. 7 is a side view of the free standing elliptical beam load cell with a vessel installed on it; 
     FIG. 8 is a top view of one embodiment of the free standing triangular beam load cell; 
     FIG. 9 is a front view of the free standing triangular beam load cell and strain gage of FIG. 8; 
     FIG. 10 is a cross section view of the free standing triangular beam load cell arch bridges and strain gages; 
     FIG. 11 is a top view of the free standing triangular beam load cell with a vessel installed on it; 
     FIG. 12 is a side view of the free standing elliptical beam load cell with a vessel installed on it; 
     FIG. 13 is a top view of an alternate triangular load cell; 
     FIG. 14 is a front view of the free standing triangular beam load cell and strain gage of FIG. 15; 
     FIG. 15 is a cross section view of the free standing triangular beam load cell arch bridges and strain gages; 
     FIG. 16 is a cross sectional view of the I-Beam configuration of the load cell of FIG. 16; 
     FIG. 17 is a top view of one embodiment of the free standing rectangular beam load cell; 
     FIG. 18 is a front view of the free standing rectangular beam load cell and strain gage of FIG. 17; 
     FIG. 19 is a cross section view of the free standing rectangular beam load cell arch bridges and strain gages; 
     FIG. 20 is a top view of another embodiment of the free standing rectangular dual beam load cell; 
     FIG. 21 is a front view of the free standing rectangular dual beam load cell and strain gage of FIG. 20; 
     FIG. 22 is a cross section view of the free standing rectangular dual beam load cell arch bridges and strain gages; 
     FIG. 23 is a top view of a free standing circular beam load cell; 
     FIG. 24 is a front view of the free standing circular beam load cell and strain gage of FIG. 23; 
     FIG. 25 is a cross section view of the free standing circular beam load cell arch bridges and strain gages; 
     FIG. 26 is a top view of a free standing octagonal multi-beamed load cell; 
     FIG. 27 is a front view of the free standing octagonal multi-beamed load cell and strain gage of FIG. 26; 
     FIG. 28 is a side view of an alternate elliptical beam load cell with a step and strain gage bridge; 
     FIG. 29 is a cross section view of the free standing octagonal multi-beamed load cell arch bridges and strain gages; 
     FIG. 30 is a side view of an alternate elliptical beam load cell with a step and circular strain gage cutout; 
     FIG. 31 is a side view of an additional elliptical beam load cell with dual steps and circular strain gage cutout; 
     FIG. 32 is a side view of an additional elliptical beam load cell with singular step, oval cutout and dual strain gage sets; and, 
     FIG. 33 is a side view of an additional elliptical beam load cell with dual cutouts and strain gage sets. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The prior art limitations due to mounting, applications, thermal degradation and response to non-axial loads are solved by a complete redesign of the beam load cell as disclosed herein. The unique stand free multi beamed load cell disclosed can be used as a force-sensing means for detecting load/weight or slight increments in load/weight change. The axial force applied to the disclosed stand free multi beamed load cell is either in the form of a mounted load or a suspension load. This load is applied to the center of the beam. The beam, which functions as a spring element, is supported on both ends with tabs. This can be a singular beam or consist of a dual, triple, quad or multi-number of beams. These multi-beam load cell layouts are in the form of an elliptical, rectangle, triangle, circle, square, or any other geometric shape. In this rim design of multi-beam load cells, each beam is independent of the other. A through hole for load placement is centralized on the side of each beam. The load is evenly distributed to the number of beams that make up a free standing load cell. For bending beam load cell applications, a compression strain gage is placed on the beams top bridge above the load placement hole. The tension strain gage is placed on the beams bottom bridge below the load placement hole. For shear-web beam load cell applications, a recessed hole is located to the left and to the right of the beams load placement hole on both sides of the beam. The recessed holes opposite each other creates an I-beam in that area. Strain gages are placed on the bottom of the four recessed holes. The free standing beam load cell as disclosed herein mounts in a relaxed horizontal position. Singular ball bearings or dowel pins made from hardened steel or stainless steel are protruding out of the bottom surface of the tab ends. This allows the multi-beam load cell to stand freely on a flat, stable support base. Only a point contact is made between the singular ball bearings or dowel pins and the flat, smooth support base. A shoulder bolt with a compression spring around its shoulder protrudes through a counterbored hole in the center of each tab end and is screwed into the support base. The resistance created by the compression spring keeps the support base from becoming tightly fixed to the singular ball bearings or dowel pins. This allows full flexing of the beam load cell which will minimize the deflection on the outside portions of the beam and tab ends while creating the highest strain level in the centralized area of the beam where the load is applied. This improves the performance characteristics such as linearity, hysteresis, creep/relaxation and fatigue life. Should the support base have a high or low temperature, the point contact would minimize the destabilizing temperature effects on the beam and the strain gage response. 
     The free standing bending beam load cell  100  in an elliptical configuration, is illustrated in FIGS. 1,  2  and  3 . The optimum material for manufacturing the beam load cells disclosed herein is based on its application. For high-force beam load cells, high-modulus materials are generally used, such as steel alloys 4140 and 4340. In situations requiring corrosion resistance, stainless steel alloys 17-4PH, 17-7PH, PH 15-7 Mo and  15 - 5  PH are recommended. In the case of low-force applications, low-modulus materials such as the aluminum alloys 2024-T4, T351 or T81 are used. The beams  102  and  104  with tab ends  110  and  112  are machined from one piece of material in the form of a rim. If the application requires a large mounting or suspension load, each individual beam  102  and  104  could be machined separately and then attached to the individual tab ends  110  and  112  to form a rim. This would make up a beam/tab end assembly. A preferred option for large loads would be to use two or more free standing beam load cells  100 . The tab ends  110  and  112  serve to support the load cell  100  on the support ledges  174  as shown in FIG.  4 . Although the tab ends  110  and  112  can be either permanently or removably affixed to the support ledges  174  by various means known in the art, the preferred method is through use of ball bearings  172  in combination with shoulder bolts  168  and springs  170  positioned in the counterbored through holes  158  and  160 . In certain applications, the free standing beam load cell tabs  110  and  112  do not have to be attached to the support ledges  174 . 
     The beams  102  and  104  side centralized point is the location for machining the load placement hole  150  and  152 . Tension arch bridges  126  and  128  are machined into the under surface of the beams  102  and  104 , while compression arch bridges  118  and  120  are machined on top of the surface. The compression arch bridges  118  and  120 , along with the tension arch bridges  126  and  128 , serve to focus the flexing of beams  102  and  104  at the bridges when an axial load  184  is applied. The thickness of the load cell is reduced by approximately 60-80% at the point of the arch bridges  118 ,  120 ,  126  and  128 . One of the arch bridges is equipped with a half or full Wheatstone bridge circuit, or equivalent, to provide a read out of the amount of strain currently present on the load cell  100 . A basic Wheatstone bridge measuring circuit consists of two (half) or four (full) strain gage grids electronically connected and is recommended for use with the instant invention due to its accuracy and sensitivity with static strain circuits. Alternate bridge designs can be used and are disclosed further herein in FIGS. 29-33. Current is fed to the beam load cell  100  through the bridge excitation voltage line  178 . The amount of load  184  placed at the center of the beam  102  and  104  varies the strain of the metal, which in turn alters the current. The change in current is registered at the Whetstone bridge  126  and fed through the bridge output voltage line  180  to the strain gage instrumentation  182 . A base level strain is set at time of manufacture and a lessening of this base level indicates less weight being placed on the load cell. The electronics registering the load  184  change can be configured in any method known in the art. 
     In FIG. 4 the cutaway side view of the tab end  112  is shown mounted to the support ledge  174  through use of a shoulder bolt  168 . The ball bearings  172  are equally spaced within the tab end  112  from the counterbored through hole  160  and screw receiving area  176 . The ball bearings  172  are snapped into and maintained in the bearing receiving notch  166  by a friction fit. A threaded receiving area  176  is machined into the support ledge  174  to receive the shoulder bolt  168  and secure the beam load cell. A counterbore  160  is machined into the tab end  112  to provide a receiving area for the spring  170  and shoulder bolt head  168 . The compression spring  170  has a diameter less than the machined counterbore  160  and head of the shoulder bolt  168 , thereby maintaining the compression spring  170  between the head of the shoulder bolt  168  and screw receiving area  176 . Tightening the shoulder bolt  168  pulls the tab  112  and the support base ledge  174  together until contact is made between the ball bearings  172  and the support base ledge  174 . The resistance created by the compression spring  170  keeps the support base ledge  174  from becoming tightly fixed to the ball bearings  172 . This floating adjustment will keep a twisting action off the load cell. 
     In FIG. 5 the cutaway front view shows the tab end  112  with the singular ball bearing  112  standing on the support ledge  174 . If the support ledge  174  is outside normal temperature endurance for the beam  102  and strain gage (not shown) response, the point contact between the singular ball bearing  172  and the support ledge  174  minimizes the destabilizing temperature effects. The free standing elliptical beam load cell  100  is shown installed with the tab ends  110  and  120  on the support ledge  174  in FIGS. 6 and 7. This illustrates an axial load  184  held in suspension by the load cell beams  102  and  104 . The vessel  186  has two load rods  192  which protrude into the load placement holes  150  and  152  in their respective beams  102  and  104 . The weight in the vessel  186  can be in liquid or solid form. The load is concentrated on the two load rods  192  which press downward in the load placement holes  150  and  151 . With the shoulder bolts and compression springs (not shown) in the counterbored through hole  158  and  160 , the free standing beam load cell flexes on singular ball bearings  172 . This allows this transfer of load on the arch bridges  118 ,  120 ,  126  and  128  to create a high level of strain which will be detected by the compression strain gages  134  and  136  and the tension strain gages  142  and  144 . With this applied load  184 , the current fed through the bridge excitation voltage line  178  is altered and fed back through the bridge output voltage line  180  to the strain gage instrumentation  182  for load/weight readout. Since the beams  102  and  104  are independent from each other, a means to reduce cost would be to place one full strain gage on the tension arch bridge  126 . This would leave the two compression and one tension arch bridges  118 ,  120  and  128  vacant. 
     The free standing bending beam load cell  200  in a triangular configuration, is illustrated in FIGS. 8,  9 , and  10 . The unit has three beams  202 ,  204  and  206  which are one piece with the three tab ends  210 ,  212  and  214 . The triangular beam load cell  200  is machined either from high-modulus steel for high force or from low-force applications. Each of the tab ends  210 ,  212  and  214  has two ball bearing receiver notches and one counterbored through hole  258 ,  260  and  262  respectively machined in. Ball bearings are  272  pressed into the notches and act as a pivot point to allow the beams  202 ,  204  and  206  to have a concentrated strain at the compression arch bridges  218 ,  220  and  222  as well as the tension arch bridges  226 ,  228  and  230 . All three beams  202 ,  204  and  206  are independent of each other so the placement of compression strain gages can be placed on beam  202 , beams  202  and  204  or beams  202 ,  204  and  206 . The same is true with the tension strain gages  242 ,  244  and  246 . The use of a full set of the mentioned strain gages on all three beams  202 ,  204  and  206  would be most efficient. The excitation voltage line  278  and bridge output voltage line  280  are connected to the strain gage instrumentation  282  which is used to calibrate the triangular beam load cell when a force is put on the load placement holes  250 ,  252  and  254 . The free standing triangular beam load cell  200  is shown installed on the support base  288  in FIGS. 11 and 12. A load base  290  is held inside the triangular beam load cell  200  with three load rods  292  which protrude into the load placement holes  250 ,  252  and  254  in their respective beams  202 ,  204  and  206 . The axial load  284  on the load base  290  is shown as a vessel  286 . Any other material item can be set on the load base  290  as well. The load is concentrated on the three load rods  292  which press downward in the load placement holes  250 ,  252  and  254 . In certain applications, its not required to use the shoulder bolt and compression spring, illustrated in FIG. 4, to hold the beam load cell in position. The unit will flex on the singular ball bearings  272 . This allows the transfer of load on the arch bridges  218 ,  220 ,  222 ,  226 ,  228  and  230  to create a high strain which will be detected by the compression strain gages  234 ,  236  and  238  and the tension strain gages  242 ,  244  and  246 . With this applied load, the current fed through the bridge excitation voltage line  278  is altered and fed back through the bridge output voltage line  280  to the strain gage instrumentation  182  for load/weight readout. Since the beams  202 ,  204  and  206  are independent from each other, a means to reduce cost would be to place one full strain gage on the tension arch bridge  226 . This would leave the three compression and two tension arch bridges  218 ,  220 ,  222 ,  228  and  230  vacant. 
     FIGS. 13-16 disclose a triangular shaped multi-beamed load cell  300  having an I-Beam construction, as illustrated in FIG.  16 . This construction allows for the load cell  300  to support heavy loads of greater than 1,000 pounds. The basic construction is similar to that of the foregoing load beams, however the use of the I-beam increases the weight capacity substantially. 
     The rectangular load cell  406  as illustrated in FIGS. 17,  18  and  19  is a free standing unit which rests on any flat surface. The solid body  402  provides an ideal surface to set miscellaneous items without the need for suspension, special cups or other devices. The shoulder bolts and compression springs (not shown) and singular ball bearings are equivalent to those described heretofore. This allows this transfer of load on the arch bridges  418  and  426  to create a high level of strain which will be detected by the compression strain gages  434  and  436  and the tension strain gages  442  and  444 . With this applied load  484 , the current fed through the bridge excitation voltage line is altered and fed back through the bridge output voltage line as described heretofore. Since the beams  102  and  104  are independent from each other, a means to reduce cost would be to place one full strain gage on the tension arch bridge  126 . This would leave the two compression and one tension arch bridges  118 ,  120  and  128  vacant. 
     The dual beam rectangular load cell  506  as illustrated in FIGS. 20,  21  and  22  is a free standing unit allows for the hanging of devices, as previously described. The beams  504  and  502  are suspended using the shoulder bolts and compression springs (not shown) and singular ball bearings which are equivalent to those described heretofore. This allows this transfer of load on the arch bridges  504  and  502  to create a high level of strain which will be detected by the compression strain gages  518  and  526  and the tension strain gages  534  and  540 . With this applied load  584 , the current fed through the bridge excitation voltage line is altered and fed back through the bridge output voltage line as described heretofore. Since the beams  502  and  504  are independent from each other, a means to reduce cost would be to place one full strain gage on the tension arch bridge  552 . This would leave the two compression and one tension arch bridges  552 . 
     The multi-beamed circular load cell  600  as illustrated in FIGS. 23,  24  and  25  is a free standing unit allows for the hanging of devices, as previously described. The beams  602 ,  604  and  606  are suspended using the shoulder bolts and compression springs (not shown) and singular ball bearings which are equivalent to those described heretofore. This allows this transfer of load on the arch bridges  602 ,  604  and  506  to create a high level of strain which will be detected by the compression strain gages  640  and  634  and the tension strain gages  618  and  626 . With this applied load  684 , the current fed through the bridge excitation voltage line is altered and fed back through the bridge output voltage line as described heretofore. Since the beams  602 ,  604  and  606  are independent from each other, a means to reduce cost would be to place one full strain gage on the tension arch bridges  652 . This would leave the two compression and one tension arch bridges  652 . 
     The multi-beamed hexagonal load cell  700  is illustrated in FIGS. 26,  27  and  28 . The beams  702 ,  704 ,  706  and  708  are suspended using the shoulder bolts and compression springs (not shown) and singular ball bearings which are equivalent to those described heretofore. This allows this transfer of load on the arch bridges  752 ,  754 ,  756  and  750  to create a high level of strain which will be detected by the compression strain gages as described heretofore  740  and  734  and the tension strain gages  718  and  726 . With this applied load  784 , the current fed through the bridge excitation voltage line is altered and fed back through the bridge output voltage line as described heretofore. Since the beams  702 ,  704 ,  706  and  708  are independent from each other, a means to reduce cost would be to place one full strain gage on the tension arch bridges  752 . This would leave the two compression and one tension arch bridges  752 . 
     FIGS. 29-33 illustrate alternate configurations to the foregoing bridges, providing variations to the heretofore disclosed spring element or bridge. In FIG. 29 the multi beam load cell  800  has a modified inverted triangle cutout as a bridge  802 . The strain gage  804  is placed directly below the single step  806 . The elliptical beam load cell  810  of FIG. 30 uses a circular cutout for the bridge  812 . The strain gage  814  is placed at the underside of the load cell  810 , opposite the singular step  816 . The elliptical load cell  820  of FIG. 31 utilizes dual steps  826  and  828  positioned on either side of the circular cutout bridge  822 . The strain gage  824  is placed on the underside of the load cell  820  below the bridge  822 . For applications requiring extreme accuracy, such as in the medical field, dual strain gage sets are used to average the weight changes. In FIG. 32 an oval cutout is used in the elliptical load cell  830  for the bridge  832 . Dual strain gage sets  834  and  836  are placed within the bridge  832  on either side of the step  838 . Multi-load cell  840  of FIG. 33 has dual circular cutout bridges  842  and  844  placed at either end of the step  850 . The strain gage sets  846  and  848  are placed below the bridges  842  and  844  on the underside of the load cell  840 . 
     The embodiments disclosed in FIGS. 29 and 32 offer the advantage of the placement of a hermetic seal for ultimate protection against moisture. FIGS. 30,  31  and  32  provide the advantage of a lower production cost. The circular cutout designs are drilled which reduces machining time. Any of the foregoing combinations can be used in conjunction with one another to produce the optimum elliptical beam load cell for each individual application. 
     Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the example chosen for the purposes of disclosure, and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention.