Abstract:
A drive coupling arrangement for transmitting torque from a drive arrangement to a gear assembly under test has a first coupler portion attached to the gear assembly under test. The coupler has a polygonal cross-sectional configuration and a plurality of substantially planar surfaces that extend parallel to the predetermined length of axis, in the form of an assembly nut of the gear assembly under test at a rotatory terminal thereof. A second coupler portion is coupled to the drive arrangement and has an internal cross-sectional configuration that accommodates the polygonal cross-sectional configuration of the first coupler portion. The second coupler portion has a plurality of engagement portions that communicate exclusively with a predetermined number of the substantially planar surfaces of the first coupler portion, and is axially translatable along the first coupler portion. Axial loading is absorbed by an elastomeric insert that limits the extent of the engagement between first and second coupler portions. The first and second coupler portions exert a torque against one another via the substantially planar surfaces and the engagement portions, over a predetermined range that is limited by the elastomeric insert, which additionally absorbs axial loading. A resilient biasing element urges the second coupler portion axially upward toward the first coupler portion. An isolation support supports the energy transfer system so as to be translatable in at least one plane of freedom.

Description:
RELATIONSHIP TO OTHER APPLICATION  
       [0001]    This application is a divisional patent application and a continuation-in-part patent application of U.S. Ser. No. 09/107,091, filed Jun. 29, 1998. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates generally to systems for testing electrical and mechanical energy transfer systems that exhibit vibratory and other responses to electrical or mechanical input energy, and more particularly, to an arrangement that isolates a mechanical or electrical system under test and produces signals and data corresponding to a plurality of operating characteristics of the system under test in response to the input energy.  
           [0004]    Description of the Related Art  
           [0005]    Noise testing of gears to date has been attempted by methods that rigidly mount the gear or axle assemblies in one or more planes. Some other previous attempts chose to have one of the rigidly mounted planes resonate at a frequency sympathetic to gear noise. None of these methods, or any other rigidly mounted test system has been successful. This is due to the lack of repeatability of the previous systems, largely as a result of interacting resonances, and external background noise that is transferred through the rigid mounting system. This is especially true in a production test environment.  
           [0006]    These deficiencies in the prior art are most evident in the axle industry. At this time, the only widely accepted way of measuring gear noise is to acquire an assembled axle and install it in a test car. A specially trained individual then drives the car over its typical operating range while carefully listening for axle gear noise. The individual rates the quality of axle gear noise on a scale that is typically 0 to 10. Ten is usually a perfect axle, i.e. one that has no gear noise. This method is made difficult by:  
           [0007]    1 The lack of available trained noise rating individuals  
           [0008]    2 The cost of test cars.  
           [0009]    3 The lack of quality roads or test tracks on which to perform a repeatable and accurate test.  
           [0010]    4 The time required for each test.  
           [0011]    5 The subjectivity that humans bring into the rating system  
           [0012]    Typically less than a dozen axles can be tested by a major manufacturer in one shift due to all of the above complications. This low number is not statistically valid when it is considered that most manufacturers make thousands of axles each day. Even with all of the above problems, human testers in cars are the only widely accepted method of axle testing in the industry due to the lack of a better more reliable testing method. This lack of a scientific basis for rating axles and gear systems is made worse when the reader considers that modem cars are extremely quiet, and are evolving to become more quite. This market direction increases the pressure on axle and other gear manufacturers to make their products quieter. There is a need for a system that offers gear and axle manufacturers a repeatable, reliable, accurate and practical way of measuring gear noise in production or laboratory environments.  
           [0013]    It is, therefore, an object of this invention to provide a system for testing an energy transfer system, such as a vehicle axle, quickly and inexpensively, and achieving repeatable results.  
         SUMMARY OF THE INVENTION  
         [0014]    The foregoing and other objects are achieved by this invention which provides, in a first apparatus aspect thereof, a drive coupling arrangement for transmitting substantially exclusively torque from a drive arrangement to a gear assembly under test. In accordance with the invention, the drive coupling arrangement is provided with a first coupler portion attached to the gear assembly under test. The coupler has a polygonal cross-sectional configuration that extends continuously over a predetermined length of axis. The polygonal cross-sectional configuration has a plurality of substantially planar surfaces that extend parallel to the predetermined length of axis. In addition, there is provided a second coupler portion with an internal cross-sectional configuration that accommodates the polygonal cross-sectional configuration of the first coupler portion. The second coupler portion has a plurality of engagement portions that communicate exclusively with a predetermined number of the substantially planar surfaces of the first coupler portion. The second coupler is axially translatable along the first coupler portion for a portion of its predetermined length of axis. In this manner, the first and second coupler portions exert a torque against one another via the substantially planar surfaces of the first coupler portion and the engagement portions of the second coupler portion, over a predetermined range of the portion of the predetermined length of axis. In addition, a resilient insert is installed within the second coupler portion for limiting the extent of axial translation between the plurality of engagement portions of said second coupler portion along said first coupler portion.  
           [0015]    In one embodiment of the invention, the first coupler portion is in the form of an assembly nut of the gear assembly under test at a rotatory terminal thereof. The polygonal cross-sectional configuration corresponds to a hexagon and has six substantially planar surfaces. The second coupler portion has three engagement portions that engage three respective substantially planar surfaces of the first coupler portion. The second coupler portion is coupled to the drive arrangement.  
           [0016]    A resilient biasing element urges the second coupler portion axially toward the first coupler portion. The predetermined length of axis is substantially vertically arranged, the first coupler portion being disposed axially superior to the second coupler portion. The resilient biasing element urges the second coupler portion axially upward toward the first coupler portion, whereby the first coupler portion communicates axially with the resilient insert. In a specific illustrative embodiment of the invention, the resilient insert is formed of ultra-high molecular weight polyethylene and absorbs axial loading between the first and second coupler portions.  
           [0017]    In accordance with a further apparatus aspect of the invention, there is provided an arrangement for isolating an energy transfer system while it is subjected to a test process for noise, the energy transfer system being of the type having an energy input and at least one energy output. In accordance with the invention, the arrangement is provided with a base for supporting the arrangement and the energy transfer system. An isolation support supports the energy transfer system whereby the energy transfer system is translatable in at least one plane of freedom with respect to the base. Additionally, an engagement arrangement is provided for securing the energy transfer system to the isolation support, the engagement arrangement having a first position with respect to the base wherein the energy transfer system is installable on, and removable from, the isolation support, and a second position wherein the energy transfer system is secured to the isolation support. A first coupler portion is attached to the gear system, the coupler portion having a polygonal cross-sectional configuration that extends continuously over a predetermined length of axis. The polygonal cross-sectional configuration has a plurality of substantially planar surfaces that extend parallel to the predetermined length of axis. There is additionally provided a second coupler portion having an internal cross-sectional configuration that accommodates the polygonal cross-sectional configuration of the first coupler portion. The second coupler portion has a plurality of engagement portions that communicate exclusively with a predetermined number of the substantially planar surfaces of the first coupler portion, and are axially translatable along the first coupler portion for a portion of the predetermined length of axis. Thus, the first and second coupler portions exert a torque against one another via the substantially planar surfaces of the first coupler portion and the engagement portions of the second coupler portion.  
           [0018]    In one embodiment, there is further provided an energy supply coupled to the energy transfer system for supplying energy thereto when the engagement arrangement is in the second position. The energy transfer system is, in one embodiment of the arrangement of the present invention, a mechanical energy transfer system, and in such an embodiment, the energy supply, which is a part of the arrangement of the invention, is in the form of a source of rotatory mechanical energy. A rotatory coupler couples the source of rotatory mechanical energy to the energy transfer system. The first coupler portion, in this embodiment of the invention, is an hexagonal assembly nut. The second coupler portion is resiliently urged toward the first coupler portion by operation of a resilient spring.  
           [0019]    In a highly advantageous embodiment of the invention, the mechanical energy transfer system test has forward and reverse directions of operation, and drive and coast modes of operation for each of the forward and reverse directions of operation. The mechanical energy transfer system contains at least a pair of meshed elements, at least one of the pair of meshed elements being a gear having a plurality of gear teeth thereon, the gear teeth each having first and second gear tooth surfaces for communicating with the other element of the pair of meshed elements. A mechanical energy transfer communication between the pair of meshed elements is effected primarily via the respective first gear tooth surfaces during forward-drive and reverse-coast modes of operation, and primarily via the respective second gear tooth surfaces during forward-coast and reverse-drive modes of operation. With such a system under test, the arrangement of the present invention is provided with a first acoustic sensor arranged at a first location in the vicinity of the mechanical energy transfer system for producing a first signal that is responsive substantially to a qualitative condition of the first gear tooth surfaces. A second acoustic sensor is arranged at a second location in the vicinity of the mechanical energy transfer system, and produces a second signal that is responsive substantially to a qualitative condition of the second gear tooth surfaces. The first and second locations are distal from each other on opposite sides of the pair of meshed elements.  
           [0020]    In a further embodiment of the invention, the rotatory coupler is provided with a resilient coupler arrangement that transmits rotatory motion thereacross over a predetermined range of rotatory motion transmission angles. The resilient coupler arrangement is provided with first and second coupler portions, the first and second coupler portions being rigidly coupled rotationally to each other. Additionally, they are axially resiliently coupled to each other, whereby the first and second coupler portions are synchronously rotatable over the predetermined range of rotatory motion transmission angles.  
           [0021]    In yet a further embodiment of the invention, the resilient coupler arrangement is provided with first and second coupler portions, the first and second coupler portions being rigidly coupled rotationally to each other, and radially resiliently coupled to each other. Thus, the first and second coupler portions are synchronously rotatable over a predetermined range of axial displacement.  
           [0022]    A torque sensor advantageously is interposed, in a highly advantageous embodiment, between the source of rotatory mechanical energy and the energy transfer system. The torque sensor produces a signal that is responsive to a torque applied by the source of rotatory mechanical energy to the energy transfer system. The torque sensor is provided with a torque-transmitting element that has a predetermined deformation characteristic. Thus, the torque-transmitting element becomes deformed in response to the torque that is applied by the source of rotatory mechanical energy to the energy transfer system. In this embodiment of the invention, the torque sensor further is provided with a strain sensor that is coupled to the torque-transmitting element for producing a strain signal responsive to the predetermined deformation characteristic of the torque-transmitting element. The strain signal, therefore, is proportional to the torque.  
           [0023]    It is very advantageous to determine the residual torque required to initiate motion of the system under test. The torque sensor is therefore arranged to produce a static torque signal that is responsive to the magnitude of the torque required to initiate rotatory motion in the mechanical energy transfer system. In addition, it is advantageous that the torque sensor be arranged to produce a dynamic torque signal that is responsive to the magnitude of torque required to maintain rotatory motion in the mechanical energy transfer system.  
           [0024]    In accordance with a further apparatus aspect of the invention. there is provided an arrangement for isolating a mechanical drive system for a vehicle while it is subjected to a testing process, the drive system being of the type having a rotatory input and at least one rotatory output. In accordance with the invention, the arrangement is provided with a base for supporting the arrangement and the mechanical drive system. An isolation support supports the mechanical drive system whereby the mechanical drive system is translatable in at least one plane of freedom with respect to the base. An engagement arrangement secures the mechanical drive system to the isolation support, the engagement arrangement having a first position with respect to the base wherein the mechanical drive system is installable on, and removable from, the isolation support, and a second position wherein the mechanical drive system is secured to the isolation support. An engagement driver is coupled to the base and to the engagement arrangement for urging the engagement arrangement between the first and second positions. The engagement arrangement is coupled to the engagement driver when the engagement arrangement is in the first position, and isolated from the engagement driver when the engagement arrangement is in the second position. In addition, a rotatory drive applies a rotatory drive force to the mechanical drive system, and a drive coupler transmits a torque from the rotatory drive to the rotatory input of the mechanical drive system. The drive coupler is itself provided with a first coupler portion attached to the mechanical drive system, the coupler having a polygonal cross-sectional configuration that extends continuously over a predetermined length of axis. The polygonal cross-sectional configuration has a plurality of substantially planar surfaces that extend parallel to the predetermined length of axis. Additionally, the drive coupler is provided with a second coupler portion having an internal cross-sectional configuration that accommodates the polygonal cross-sectional configuration of said first coupler portion. The second coupler portion has a plurality of engagement portions that communicate exclusively with a predetermined number of the substantially planar surfaces of said first coupler portion, and are axially translatable along the first coupler portion for a portion of the predetermined length of axis. Thus, the first and second coupler portions exert a torque against one another via the substantially planar surfaces of said first coupler portion and the engagement portions of the second coupler portion, over a predetermined range of the portion of the predetermined length of axis.  
           [0025]    In a mechanical embodiment of the invention. there are additionally provided a rotatory load for applying a rotatory load to the mechanical drive system, and a load coupler for coupling the rotatory load to the rotatory input of the mechanical drive system. The mechanical drive system is in the form of a drive-transmitting component for a motor vehicle. In such an embodiment, the rotatory load applies a controllable rotatory load thereto to simulate a plurality of vehicle operating conditions. These include, for example, gear drive and coast conditions, as well as a gear float condition.  
           [0026]    In accordance with a method aspect of the invention, there is provided a method of testing a gear assembly of the type having an input and an output. The method includes the steps of:  
           [0027]    installing the gear assembly on a mounting arrangement that resiliently permits motion of  
           [0028]    installing the gear assembly on a mounting arrangement that resiliently permits motion of the gear assembly in all directions, the gear assembly having an hexagonal assembly nut installed at a rotatory input thereof;  
           [0029]    urging a coupler having three engagement surfaces resiliently and continuously toward the hexagonal nut, whereby the three engagement surfaces communicate with three corresponding surfaces of the hexagonal assembly nut;  
           [0030]    applying a torque at the coupler, whereby the gear assembly is rotatably operated;  
           [0031]    applying a load at the output of the gear assembly; and  
           [0032]    sensing a predetermined operating characteristic of the gear assembly.  
           [0033]    In one embodiment of this method aspect of the invention, the step of sensing is provided with the step of detecting acoustic energy issued by the gear assembly. Also, the step of detecting acoustic energy issued by the gear assembly is provided with the step of placing a microphone n the vicinity of the gear assembly.  
           [0034]    In accordance with a further embodiment of this method aspect of the invention, the drive and coast modes of operation are cyclical over a period that is shorter than a cycle period of the input of the gear assembly. Conversely, the period can be longer than a cycle period of the input of the gear assembly. This will depend, to an extent, upon the operating ratios within the system under test. In situations where the system under test is an electrical system, harmonics and signal distortions may affect the apparent cycle period in relation to the cycle period of the input energy.  
           [0035]    In an advantageous embodiment, the first and second sensors are disposed at respective locations that are distal from each other, with the gear assembly interposed therebetween. This enables distinguishing between operating modalities of the system under test, as well as facilitating analysis of operating characteristics of the system under test that have directional components. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0036]    Comprehension of the invention is facilitated by reading the following detailed description, in conjunction with the annexed drawing, in which:  
         [0037]    [0037]FIG. 1 is a front plan representation of an arrangement for isolating a system under test, constructed in accordance with the principles of the invention;  
         [0038]    [0038]FIG. 2 is a side plan view of the embodiment of FIG. 1;  
         [0039]    [0039]FIG. 3 is an exploded plan representation of the embodiment of FIG. 1 showing certain drive components;  
         [0040]    [0040]FIG. 4 is a top plan view of the embodiment of FIG. 1;  
         [0041]    [0041]FIG. 5 is a partially phantom front plan view of a drive arrangement that supplies rotatory mechanical energy to an isolate mechanical energy transfer system under test;  
         [0042]    [0042]FIG. 6 is side plan view of the drive system of FIG. 5;  
         [0043]    [0043]FIG. 7 is a side plan representation of the drive system as shown in FIG. 6, enlarged to show greater detail;  
         [0044]    [0044]FIG. 8 is a side plan view of a coupler that couples the drive system to the mechanical system under test;  
         [0045]    [0045]FIG. 9 is a top plan view of the coupler of FIG. 8 showing therein three engagement surfaces for coupling with the flanks of an hexagonal nut (not shown in this figure) at the rotatory input of the mechanical system under test;  
         [0046]    [0046]FIG. 10 is a plan representation of a clamping arrangement constructed in accordance with the principles of the invention, the clamping arrangement being shown in two positions;  
         [0047]    [0047]FIG. 11 is a compact drive arrangement constructed in accordance with the invention for coupling the rotatory output of a mechanical energy transfer system under test to a rotatory load;  
         [0048]    [0048]FIG. 12 is a partially cross-sectional side plan view of the compact drive arrangement of FIG. 11 further showing a resilient coupling element;  
         [0049]    [0049]FIG. 13 is a partially phantom enlarged representation of the resilient coupling element shown in FIG. 12;  
         [0050]    [0050]FIG. 14 is an isometric representation of an arrangement for isolating a system under test, constructed in accordance with the principles of the invention, the system under test being an electrical energy transfer device;  
         [0051]    [0051]FIG. 15 is a process diagram of a typical process for conducting an energy analysis;  
         [0052]    [0052]FIG. 16 is a process diagram of a process for conducting an energy analysis in accordance with the principles of the present invention;  
         [0053]    [0053]FIG. 17 is a process diagram of a process for conducting an energy analysis in accordance with the principles of the present invention for determining bumps and nicks in a mechanical energy transfer system;  
         [0054]    [0054]FIG. 18 is a partially cross-sectional side plan view of a compact drive arrangement further showing a resilient engagement limiting element that precludes engagement beyond a predetermined extent between the coupler that couples the drive system and the mechanical system under test; and  
         [0055]    [0055]FIG. 19 is a top end view of the arrangement of FIG. 18. 
     
    
     DETAILED DESCRIPTION  
       [0056]    [0056]FIG. 1 is a front plan representation of an arrangement for isolating a system under test, constructed in accordance with the principles of the invention. As shown in this figure, an isolating arrangement  10  is arranged to support in relative isolation a mechanical drive system in the form of a differential  11 . Differential  11  is of the type that is conventionally employed in a motor vehicle (not shown) and is intended to be tested for a variety of operating conditions, using isolating arrangement  10 . The differential is of the type having a rotatory input  13  that receives rotatory mechanical energy from a drive arrangement (not shown in this figure) that will be described below. In addition, differential  11  has rotatory outputs  14  and  15 , respectively, that produce rotatory mechanical energy in response to the rotatory input energy received at rotatory input  13 . When employed in a motor vehicle (not shown), differential  11  is coupled to the drive shaft (not shown) of the vehicle at rotatory input  13 , and rotatory outputs  14  and  15  are coupled to the vehicle&#39;s drive wheels (not shown).  
         [0057]    Differential  11  is shown to be supported on a pair of supports  18  and  19  that are installed on a base  20 . Each of supports  18  and  19  has installed thereon a respectively associated one of resilient isolating elements  22  and  23 . A respective one of engagement arrangements  24  and  25  are installed on resilient isolating elements  22  and  23 . The engagement arrangements will be described in detail hereinbelow and serve to couple differential  11  at its rotatory outputs  14  and  15  whereby it is secured with respect to base  20 , yet limited motion of differential  11  is permitted relative to base  20 .  
         [0058]    [0058]FIG. 1 further shows a pair of load arrangements  28  and  29  that apply a controllable load to respectively associated ones of rotatory outputs  14  and  15 . The rotatory outputs are coupled mechanically (coupling not shown in this figure) to load arrangements  28  and  29  in a manner that facilitates limited motion of the rotatory outputs with respect to base  20 . The permissible displacement of differential  11  in accordance with the present invention is along multiple planes of freedom, and, as will be described hereinbelow, the coupling arrangements (not shown in this figure, between rotatory outputs  14  and  15  and their respective associated load arrangements  28  and  29  permit axial and rotative degrees of freedom of motion. Such couplings will be described with respect to FIGS.  9 - 12 .  
         [0059]    [0059]FIG. 2 is a side plan view of the embodiment of FIG. 1. This figure is taken along line  2 - 2  of FIG. 1. In addition to some of the structure shown in FIG. 1, FIG. 2 shows a safety cover  30  that protects the user (not shown) of the isolating arrangement in accordance with established safety standards. Elements of structure that correspond to those discussed hereinabove with respect to FIG. 1 are similarly designated.  
         [0060]    [0060]FIG. 2 shows engagement arrangement  24  having engagement arms  32  and  33  that are shown in an engaged position around rotatory output  14 . As will be described hereinbelow, engagement arms  32  and  33  have engaged and disengaged (not shown) positions in response to actuation of an engagement driver which is shown in this figure in the form of a linear actuator  35 ,  
         [0061]    A safety cover  30  is shown to be coupled to a cover hinge  31 , whereby the safety cover is rotatable thereabout in response to actuation of a cover actuator  34 . In operation, the safety cover is arranged in the position shown in the figure during performance of the testing procedure, and it is raised to a position that is not shown in order to facilitate installation and removal of the system under test, i.e., differential  11 .  
         [0062]    [0062]FIG. 2 additionally shows a drive motor  40 , which in this embodiment, is coupled to a belt pulley  42 , shown in FIG. 1.  
         [0063]    [0063]FIG. 3 is an exploded plan representation of the embodiment of FIG. 1 showing certain drive components. Elements of structure that have previously been discussed are similarly designated. The drive arrangement, and the manner by which it is coupled to differential  11 , will be discussed in detail hereinbelow with respect to FIGS.  5 - 8 .  
         [0064]    [0064]FIG. 4 is a top plan view of the embodiment of FIG. 1. Elements of structure that have previously been discussed are similarly designated. Moreover, differential  11  has been removed, and therefore, is not visible in this figure.  
         [0065]    In FIG. 4, each of load arrangements  28  and  29  has associated therewith a respective one of load coupler arrangements  44  and  45 , each of which is coupled by a respective load belt  46  and  47  to a respective one of load units  48  and  49 . Load arrangement  28  will be described in detail hereinbelow with respect to FIG. 11, and the load coupler arrangements,  44  and  45 , will be described in detail with respect to FIG. 12. Referring to FIG. 4, rotatory outputs  14  and  15  (not shown in this figure) are coupled (coupling not shown in this figure) to respectively associated ones of load coupler arrangements  44  and  45  which, as previously noted, provide multiple degrees of freedom of movement. Load units  48  and  49 , in this specific illustrative embodiment of the invention, are in the form of electric brakes or electric motors. Of course, other forms of loads can be employed in the practice of the invention. In embodiments of the invention where the load units are in the form of electric motors, such motors can provide simulated braking and driving operations. Thus, in the present embodiment where the isolating arrangement is directed to the testing of a drive component for a vehicle, such as a differential, the load units can be operated in a drag, or generator mode, wherein the differential would be operated in a simulated drive mode. That is, the load is driven by the differential. Alternatively, the load units can be operated in a motor drive mode, wherein the differential is itself driven by the load, i.e., operated in a simulated coast mode. In a highly advantageous embodiment of the invention, the differential can be operated and thereby tested in drive and coast modes of operation in forward and reverse directions. It is to be remembered that during drive and coast modes of operation different gear tooth surfaces (not shown) within the differential are caused to communicate with one another, thereby affording enhanced testing capability.  
         [0066]    [0066]FIG. 5 is a partially phantom front plan view of a drive arrangement that supplies rotatory mechanical energy to an isolated mechanical energy transfer system under test. Elements of structure that have previously been discussed are similarly designated. As shown in this figure, output shafts  52  and  53  are shown protruding from the fragmented representation of rotatory outputs  14  and  15 , respectively. The output shafts rotate in response to the application of a rotatory drive at rotatory input  13 .  
         [0067]    [0067]FIG. 6 is side plan view of the drive system of FIG. 5. The operation of the drive arrangement that will supply a rotatory drive to rotatory input  13  of differential  11  is described herein with reference to FIGS.  5 - 9 . As stated, drive motor  40  is coupled via a drive belt  41  to belt pulley  42  which is installed on a drive shaft  55  that is shown in the figures to extend axially vertically. Belt pulley  42  contains a torque sensing arrangement (not shown) that provides an electrical signal responsive to torque differential between the belt pulley and drive shaft  55 . The electrical signal responsive to torque (not shown) is available at signal output connector  56 .  
         [0068]    In this specific illustrative embodiment of the invention, the torque sensing arrangement contained within belt pulley  42  and its associated signal output connector  56  is in the form of a strain gauge (not shown) installed to respond to the displacement of a web (not shown). That is, in the practice of this aspect of the invention, torque is transmitted across a web whereby, for example the torque is applied across the periphery of the web, and an output shaft is coupled nearer to the center of the web. Of course, these may be reversed. As torque is applied, the web is correspondingly deformed, and a strain gauge installed on the web measures the deformity in the web in response to the applied torque. Over a predetermined range of torque, the deformation of the web, as determined by the strain gauge, can be correlated to the magnitude of the applied torque. Signal output connector  56 , in this specific illustrative embodiment of the invention, additionally contains circuitry (not shown) that is AC coupled to the torque sensing arrangement, and that modulates and demodulates the resulting torque signal.  
         [0069]    Shaft  55  is shown in FIG. 6 to be supported against axially transverse motion by a pair of journal bearings  58 . Drive shaft  55 , therefore, rotates about its axis in response to a rotatory drive energy supplied by drive motor  40  and delivered thereto by drive belt  41 .  
         [0070]    A coupling arrangement  60  that is fixed axially onto drive shaft  55  permits resilient axial displacement of a coupling shaft  62  with respect to the axis of drive shaft  55 . Coupling arrangement  60  is formed of a flanged member  61  that is coupled to rotate with drive shaft  55 . A further flanged member  63  is shown to be engaged with coupling shaft  62 . Flanged members  61  and  63  are each provided with respective resilient elements  65  that facilitate the permissible axial displacement of coupling shaft  62  with respect to the central axis defined by drive shaft  55 . The rotatory energy is transmitted across intermediate element  67 , with which resilient elements  65  communicate.  
         [0071]    [0071]FIG. 7 is a side plan representation of the drive system as shown in FIG. 6, enlarged to show greater detail. As shown in FIGS. 6 and 7, the uppermost end of coupling shaft  62  is arranged to be connected to rotatory input  13  of differential  11  (shown in fragmented form in these figures). Differential  11  is of the conventional type having an hexagonal nut  69  (FIG. 7) installed at rotatory input  13 . Rotatory input  13  is formed as a pinion shaft, and hexagonal nut  13  is threadedly engaged therewith. The application of a high tightening torque to hexagonal nut  13  during assembly of the differential prevents same from loosening during application of the rotatory energy via coupling shaft  62 .  
         [0072]    [0072]FIG. 7 shows differential  11  in the process of being installed onto coupling shaft  62 , and therefore hexagonal nut  69  is shown in two positions, where it is designated  69  and  69 ′, respectively. Upon completion of the installation of differential  11 , hexagonal nut  69  becomes engaged with a nut driver  70 . Nut driver  70  is axially translatable, and therefore is shown in two positions, where it is designated  70  and  70 ′.  
         [0073]    [0073]FIG. 8 is a side plan view of nut driver  70  that couples the drive system to the mechanical system under test. FIG. 9 is a top plan view of nut driver  70  of FIG. 8 showing therein three engagement surfaces for coupling with the flanks of an hexagonal nut (not shown in this figure) at the rotatory input of the mechanical system under test. As shown in FIG. 8 and FIG. 9, nut driver  70  has a tapered outward appearance when viewed from the side (FIG. 8). Internally, nut driver  70  is provided with three engagement surfaces  71 . The engagement surfaces engage with the flank surfaces of the nut (not shown) at rotatory input  13  of differential  11 . The nut driver is, as previously noted, axially displaceable along the axis of coupling shaft  62 , and is urged upward toward the nut at the rotatory input of the differential by operation of a resilient spring member  72  (FIG. 6). Thus, the nut driver is urged into communication with the nut by operation of the light resilient bias supplied by spring  72 , thereby ensuring engagement between nut driver  70  and the hexagonal nut (not shown in FIGS. 8 and 9) at the rotatory input of differential  11 . It is to be noted that the light axial bias applied by the engagement spring is negligible and affords the differential a degree of freedom of movement in the axial direction.  
         [0074]    Referring once again to FIG. 7, sensors  73 - 76  are shown for monitoring various aspects of the operation of the differential in response to the application of the rotatory input. For example, in one embodiment of the invention, the various sensors are configured to monitor angular position of the rotatory input, transaxial displacement of the drive shaft, transaxial displacement of the differential in response to the application of the rotatory input energy, temperature in the region of the input bearing (not shown) of the differential, acoustic noise, etc.  
         [0075]    [0075]FIG. 10 is a plan representation of a clamping arrangement constructed in accordance with the principles of the invention, the clamping arrangement being shown in two positions. Elements of structure that correspond to those previously described are similarly designated. As shown, support  18  is coupled to base  20 , illustratively via one or more fasteners  140 . In this embodiment, a pair of resilient support elements  141  are disposed on support element  18  and there is supported thereon an isolation support  142 . The isolation support has a central V-shaped region  144  in the vicinity of which are installed support bearings  146  and  147 . Rotatory output  14  of differential  11  (not shown in this figure) rests on the support bearings.  
         [0076]    Engagement arms  32  and  33 , as previously noted, have first and second positions corresponding to open and closed conditions. Engagement arms  32  and  33  are shown in the closed condition, wherein rotatory output  14  is clamped to support bearings  146  and  147 . When the support arms are in the open position, identified as  32 ′ and  33 ′ (shown in phantom), the differential can be removed or installed onto isolation support  142 . Actuation of the engagement arms between the open and closed conditions is effected by operation of linear actuator  35  which is coupled to the engagement arms by respectively associated ones of engagement coupler links  148  and  149 . Engagement coupler links  148  and  149  are each coupled at a respective first ends thereof to a respectively associated one of engagement arms  32  and  33 , and they each are coupled to one another at a central pivot coupling  150 . An armature  151  of linear actuator  35  travels vertically to effect clamping and release of rotatory output  14 .  
         [0077]    When armature  151  is extended upward, engagement arms  32  and  33  are urged toward rotatory output  14 , whereby spring-loaded contacts  152  and  153  communicate with rotatory output  14 . In this embodiment, the spring-loaded contacts exert a resilient biased force against rotatory output  14  facilitating the latching of the engagement arms by operation of armature  151 . As shown, when the armature is extended fully upward, engagement coupler links  148  and  149  are urged beyond the point where their respective axes are parallel, and therefore, the engagement coupler links are biased against the underside of isolation support  142 . It should be noted that the pivot pin (not specifically shown) coupled to armature  151  at pivot coupling  150  has a smaller diameter than the apertures in the engagement coupler links. Thus, during testing of the vibration and noise of the differential, armature  151  of linear actuator  35  is essentially decoupled from engagement coupler links  148  and  149  and isolation support  142 .  
         [0078]    When it is desired to remove differential  11  from isolating arrangement  10 , armature  151  is withdrawn, whereupon pivot coupling  150  is translated to the location identified as  150 ′. In this position, the engagement arms are translated to the location shown in phantom as  32 ′ and  33 ′.  
         [0079]    In a further embodiment of the invention, one or both of spring-loaded contacts  152  and  153  is provided with a displacements sensor  154  that produces an electrical signal, or other indication, responsive to the extent of inward translation of the spring-loaded contact. Such an indication would be responsive to the outside dimension of the rotatory output of differential  11 , thereby providing a means for determining dimensional variations of the differential housing (not specifically identified in this figure) during a production run.  
         [0080]    [0080]FIG. 11 is a compact drive arrangement constructed in accordance with the invention for coupling the rotatory output of a mechanical energy transfer system under test (not shown in this figure) to a rotatory load, which will be described hereinbelow in the form of an electric rotatory device that is operable in drive and generator modes. As shown in this figure, a load arrangement  80  is provided with a load motor  81  having a belt pulley  82  arranged to rotate with a load motor shaft  83 .  
         [0081]    In this specific embodiment, pulley  82  is coupled to a further belt pulley  85  via a load belt  86 . Pulley  85  is coupled to a tubular shaft  89  having a flanged portion  90  that is arranged in axial communication with tubular shaft  89 . In a manner similar to that of pulley  46  in FIG. 6, belt pulley  82  in FIG. 11 contains a torque sensing arrangement  87  that provides an electrical signal (not shown) responsive to a torque differential between the belt pulley and load motor shaft  83 . The electrical signal responsive to torque is available at signal output connector  84 , as described below.  
         [0082]    In this specific illustrative embodiment of the invention, torque sensing arrangement  87  contained within belt pulley  82  and its associated signal output connector  84  include a strain gauge  88  installed to respond to the displacement of a web  92 . That is, in the practice of this aspect of the invention, torque is transmitted across web  92  wherein, for example, the torque is applied across the periphery of the web, and an output shaft  98  is coupled nearer to the center of the web. Of course, the application of the torque may be rotationally reversed. As the torque is applied, web  92  is correspondingly deformed, and strain gauge  88  installed on the web measures the deformity in the web in response to the applied torque. Over a predetermined range of torque, the deformation of web  92 , as determined by measurement of the electrical response of strain gauge  88  at signal output connector  84 , can be correlated to the magnitude of the applied torque.  
         [0083]    As described hereinabove with respect to signal output connector  56  in FIG. 6, in this specific illustrative embodiment of the invention, signal output connector  84  in FIG. 11 additionally contains circuitry (not shown) that is AC coupled to the torque sensing arrangement, and that modulates and demodulates the resulting torque signal. The torque signal will be to a significant extent responsive to the load or drive characteristic of load motor  81 , which is controllable by the application of appropriate electrical signals (not shown) or connection of electrical loads (not shown) at electrical terminals  99  thereof.  
         [0084]    Tubular shaft  89  is supported rotatably by ball bearings  91 . On the other side of pulley  85  is arranged a resilient element  93  that is secured to remain in communication with pulley  85  by operation of an end cap  94 . End cap  94  has internally affixed thereto a load shaft  95  that is arranged to extend along the interior length of tubular shaft  89 . Thus, notwithstanding that tubular shaft  89  is axially fixed in a support  96 , load shaft  95  will rotate with the tubular shaft but can experience displacement transverse to axis of rotation  98 . Thus, any rotatory element (not shown in this figure) that would be coupled to load shaft  95  at its associated coupler  97  would be provided with freedom of motion in any direction transverse to the axis of rotation of the load shaft, and therefore would not be constrained in the axially transverse direction.  
         [0085]    [0085]FIG. 12 is a partially cross-sectional side plan view of a compact drive arrangement similar in some respects to that of FIG. 11. This figure shows a shaft support system  100  that provides the degree of freedom of motion discussed hereinabove with respect to the embodiment of FIG. 11, and additionally provides axial thrust support. Shaft support system  100  is provided with a pulley  101  that can be coupled to another rotatory element (not shown) via a belt  102 . The pulley is fixed to a tubular shaft  104  that is axially fixed in a support  105  by ball bearings  106 . At the other end of tubular shaft  104 , the tubular shaft is expanded radially to form a shaft portion  108  having a large diameter than the central portion of the tubular shaft. A resilient coupling arrangement that is generally designated as  110  is resiliently coupled to shaft portion  108 . Resilient coupling arrangement  110  is provided with an intermediate plate  111  and an end plate  112  that are resiliently coupled to one another whereby they rotate with tubular shaft  104 . A central shaft  114  is coupled at its right-most end to end plate  112  so as to be rotatable therewith. The central shaft, however, experiences freedom of movement in all directions transverse to its axis of rotation. Any travel of central shaft  114  toward the right hand side is limited by an end stop  115 , which is arranged, in this embodiment, to provide a measure of axial adjustment. The other end of central shaft  114  is coupled to a resilient coupling arrangement which is generally designated as  117 .  
         [0086]    [0086]FIG. 13 is a partially phantom enlarged representation of the resilient coupling element shown in FIG. 12. Resilient coupling element  117  is shown in this figure in an expanded form to facilitate this detailed description. Central shaft  114  (FIG. 12) has a reduced diameter end portion  120  on which is installed a flanged washer  121  having a reduced diameter portion  122  and a flange  123  formed therearound. A further flanged element  125  is installed on reduced diameter end portion  120  of central shaft  114 , a shear pin  127  being disposed between flanged washer  121  and further flanged element  125 . In addition, an annular portion  128  is arranged to surround the flanged washer and the further flanged element, and to overlie circumferentially the axial region where resilient element  127  is disposed. All of these elements are secured to reduced diameter end portion  120  of central shaft  114  by a fastener  129  and a washer  130 . As shown, fastener  129  is threadedly engaged axially onto the end of central shaft  114 .  
         [0087]    A support portion  132  is fixed onto further flanged element  125  by fasteners  133 . Support portion  132  is resiliently coupled to a flanged shaft  135  by means of studs  136 . Thus, even though central shaft  114  enjoys freedom of movement transverse to its axis of rotation, resilient coupling arrangement  117  provides yet further freedom of movement in all directions transverse to the axis of rotation for flanged shaft  135 . Flanged shaft  135 , in one embodiment of the invention, is ultimately coupled to a rotatory output, such as rotatory output  15  of FIG. 1. Alternatively, shaft support system  100  can be used in the drive arrangement of FIG. 6 to provide significant degree of motion lateral to the axis of rotation to the drive shaft.  
         [0088]    [0088]FIG. 14 is an isometric representation of an arrangement for isolating a system under test, the isolation system being constructed in accordance with the principles of the invention. In this embodiment, the system under test is an electrical energy transfer device. As shown in this figure, an isolation support  160  isolates an electrical energy transfer device, illustratively in the form of an electrical transformer  162 . The electrical transformer is secured to an isolation base  164  by operation of a toggle locking device  165 . Isolation base  164  is mechanically isolated from a ground surface  166  by a plurality of resilient isolation elements  170 . That is, the isolation base is permitted freedom of movement in at least one plane of motion, and preferably a plurality of planes of motion, by operation of the resilient isolation elements.  
         [0089]    In the practice of this specific illustrative embodiment of the invention, the resilient isolation elements have a resilience characteristic that, as previously noted in regard of other embodiments of the invention, exclude a natural frequency of isolation support  160  and transformer  162 . The motion of the transformer and the isolation support is therefore responsive substantially entirely to the electrical energy that is transferred to or from transformer  162  via its electrical terminals  172 .  
         [0090]    [0090]FIG. 15 is a process diagram of a typical process for conducting an energy analysis of a gear system. In this known system, gears under test  180  are driven by a drive  181 , the speed of which is controlled by a speed control  183 . Information relating to the drive speed is conducted to a digital data storage system  185 .  
         [0091]    Analog sensors  187  obtain analog data from gears under test  180 , the analog signals from the sensors being conducted to an A/D converter  188 . The A/ID converter performs the conversion of the analog signals in response to a clock  190 , and the resulting digital data is conducted to digital data storage system  185 . Thus, digital data storage system  185  contains the digitized analog signals obtained from sensors  187 , which data is correlated to the speed at which gears under test  180  are driven.  
         [0092]    The digital data of digital data storage system  185  is converted to the frequency domain by subjecting same to a fast Fourier transform at step  193 . The resulting frequency components are then ordered at step  194  and analyzed manually at step  195 . At this step, the collected data, in the frequency domain, is analyzed in the context of predetermined test criteria. The pass/fail decision is then made at step  197 , and if the predetermined criteria is not met, a “fail” indication is produced at step  198 . Otherwise, a “pass” indication is issued at step  199 .  
         [0093]    [0093]FIG. 16 is a process diagram of a process for conducting an energy analysis in accordance with the principles of the present invention. As show in this figure, gears under test  201  are driven into rotation by a drive system  202 , which also drives an encoder  204 . Encoder  204  delivers signals responsive to the rotation of gears under test  201  to an A/D converter  206 . In this embodiment, the signal from encoder  204  serves as a pacing clock for the A/D converter. Information relating to noise and displacement issued by the gears under test is collected by analog sensors  207 . The resulting analog signals are conducted to A/D converter  206  where they are converted to digital signals correlated to the rotation of drive system  202 .  
         [0094]    The digital signals from A/D converter  206  are conducted to a digital data store  210  where they are maintained in correlation to the drive information obtained from encoder  204 . In this specific illustrative embodiment of the invention, the digital data is stored two-dimensionally, wherein sensor signal amplitude is identified with the y-axis, and rotational position is identified with the x-axis. The correlated digital data is subjected to a fast Fourier transform at step  212  wherein the data is converted into its frequency components.  
         [0095]    Data in the frequency domain is subjected to processing at step  214 , where a power spectrum density is created using a data window. The power spectrum density data is then analyzed harmonically at step  215  to determine its relationship with predetermined test criteria. The decision whether the power spectrum density data passes or fails with respect to predetermined test criteria is made at step  216 , and the predetermined criteria is not met, a “fail” indication is produced at step  217 . Otherwise, a “pass” indication is issued at step  218 .  
         [0096]    [0096]FIG. 17 is a diagram of a process for conducting an analysis  230  in accordance with the principles of the present invention for determining bumps and nicks in a mechanical energy transfer system. As show in this figure, gears under test  231  are driven into rotation by a drive system  232 , via a torque sensor  234 . Torque sensor  234  delivers signals responsive to the rotatory force supplied to gears under test  231  to an A/D converter  236 . Information relating to noise and displacement issued by the gears under test is collected by noise sensors  237 , which may include velocity sensors (not shown in this figure), accelerometers (not shown in this figure), microphones (not shown in this figure), etc. The resulting noise signals are conducted to A/D converter  236  where they are converted to digital signals correlated to the torque applied by drive system  232  to gears under test  231 .  
         [0097]    The digital signals from A/D converter  236  are conducted to a digital data store  240  where they are maintained in correlation to the drive information obtained from torque sensor  234 . In this specific illustrative embodiment of the invention, the digital data is stored as two two-dimensional data sets, wherein noise sensor signal amplitude is identified with a first y-axis, and time is identified with the x-axis. The amplitude of the torque signal is identified with a second y-axis, and time is again identified with the x-axis.  
         [0098]    Correlated data from digital data store  240  is subjected to analysis at step  242 , wherein peaks that occur simultaneously in the torque and noise signal waveforms are identified. These peaks are then measured at step  244  to determine whether they exceed predetermined thresholds. Those peaks that exceed the predetermined thresholds are then tested at step  245  against the harmonics of each gear tooth frequency, to determine whether the peaks correspond to anomalous conditions.  
         [0099]    The decision whether the gears under test pass or fail with respect to predetermined test criteria is made at step  246 , and if the predetermined criteria is not met, a “fail” indication is produced at step  247 . Otherwise, a “pass” indication is issued at step  248 . In some embodiments of the invention, a calculation of the severity of the bumps or nicks that caused the anomalous conditions is calculated at step  249 .  
         [0100]    In one embodiment of the process of FIG. 17, analysis is performed using only the torque data derived from torque sensor  234 , without correlation to the noise data obtained from noise sensor  237 . In this embodiment, therefore, noise sensor  237  need not be provided, as the noise signal therefrom is not used. Thus, torque sensor  234  delivers signals responsive to the rotatory force supplied to gears under test  231  to A/D converter  236 , and the digital data is stored as a single two-dimensional data set, wherein the amplitude of the torque signal is identified with the y-axis, and time is identified with the x-axis.  
         [0101]    Peaks in the torque signal are then measured at step  244  to determine whether they exceed a predetermined threshold. Those peaks that exceed the predetermined thresholds are then tested at step  245  against the harmonics of each gear tooth frequency, to determine whether the peaks correspond to anomalous conditions.  
         [0102]    The decision whether the gears under test pass or fail with respect to predetermined test criteria is made at step  246 , and if the predetermined criteria is not met, a “fail” indication is produced at step  247 . Otherwise, a “pass” indication is issued at step  248 . As previously noted, a calculation of the severity of the bumps or nicks that caused the anomalous condition is calculated at step  249 .  
         [0103]    [0103]FIG. 18 is a partially cross-sectional side plan view of a compact drive arrangement  260  constructed in accordance with the invention, further showing a resilient engagement limiting element  262  that not only precludes engagement of a nut driver  265  with an hexagonal nut  269  beyond a predetermined extent, but also absorbs axial loading that would result in a noise component. In a highly advantageous specific illustrative embodiment of the invention, resilient engagement limiting element  262  is formed ultrahigh molecular weight polyethylene (UHMW-PE) and is dimensioned to preclude communication between nut driver  265  and a flange structure  270  that is, in this embodiment, arranged to surround hexagonal nut  269 . In the arrangement illustrated in this figure, a shaft  274 , on which hexagonal nut  269  is installed, is in axial communication with resilient engagement limiting element  262 . Any communication between resilient engagement limiting element  262  and any portion of the driven mechanical system under test other than the predetermined flats of hexagonal nut  269 , such as flange structure  270 , will result in the generation of a noise that may reduce the quality of the test.  
         [0104]    [0104]FIG. 19 is a partially cross-sectional top end view of compact drive arrangement  260  of FIG. 18. As shown, nut driver  265  is configured internally to communicate with only three flats, such as flat  272  of hexagonal nut  269 , which is installed on a shaft  271 . Communication with the remaining three flats is avoided by formation of a space  274  between nut driver  265  and hexagonal nut  269 .  
         [0105]    Although the invention has been described in terms of specific embodiments and applications, persons skilled in the art can, in light of this teaching, generate additional embodiments without exceeding the scope or departing from the spirit of the claimed invention. Accordingly, it is to be understood that the drawing and description in this disclosure are proffered to facilitate comprehension of the invention, and should not be construed to limit the scope thereof.