Abstract:
An arrangement for isolating a differential axle system while it is subjected to a test process for noise, also reduces the noise contribution of the differential gear set by coupling a load directly to the differential gear set shaft. The isolation arrangement has a suspension arrangement that supports the differential axle system above the base supports. In a different embodiment, the isolation support supports the differential axle system, yet affords multiple degrees of freedom with respect to the base. The differential axle system is clamped in a manner that permits the multiple degrees of freedom with respect to the base, via an engagement arrangement that secures the differential axle system to the isolation support. The engagement arrangement has a first position with respect to the base wherein the differential axle system is installable on, and removable from, the isolation support, and a second position wherein the differential axle system is secured to the isolation support. Engagement is effected by an actuation element that is effectively decoupled from the base after clamping is achieved. Rotatory energy is provided to the differential axle system exclusively as torque, without any significant axial bias. Additionally, processes for signal analysis enable “pass/fail” determinations to be made with respect to noisiness of the system under test, as well as, the presence of bumps and nicks in the systems under test.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a divisional of U.S. Ser. No. 09/107,084, filed on Jun. 29, 1998, which issued as U.S. Pat. No. 6,389,888 on May 21, 2002. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   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. 
   2. Description of the Related Art 
   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. 
   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:
         1 The lack of available trained noise rating individuals   2 The cost of test cars.   3 The lack of quality roads or test tracks on which to perform a repeatable and accurate test.   4 The time required for each test.   5 The subjectivity that humans bring into the rating system.       

   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 modern cars are extremely quiet, and are evolving to become more quiet. 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. 
   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. 
   It is often desired in the testing of a differential gear train system to determine the qualitative characteristics of the engagement between the pinion and ring gears, excluding any gear engagement noises produced by the differential gear set. This would require both rotatory outputs to be driven at precisely the same speed, in order that the differential gear set not become active. Noise from the engagement between the members of the differential gear set will interfere with the qualitative determination of the noise being issued by the engagement between the pinion and ring gears, and is generally not otherwise sufficiently objectionable to warrant specific testing therefor, as it occurs usually only at slow vehicle speeds during turns. 
   The foregoing notwithstanding, it is expensive and complicated to test a differential axle system in a manner that excludes the noise of engagement of the members of the differential gear set, as precisely controlled loads are required at each axle output. During performance of such a test in a production environment, generally two people are required, one at each output, in order to achieve the testing throughput needed during production. 
   It is, therefore, another object of this invention to provide a testing arrangement and method for a differential axle system that permits rapid and effective testing of the engagement between the pinion and ring gears, without interference from the differential gear set. 
   SUMMARY OF THE INVENTION 
   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, at least two rotatory outputs, and a differential gear set arranged on a differential gear set shaft. 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. In addition, a rotatory drive applies a rotatory drive force to the mechanical drive system, and a first drive coupler transmits a torque from the rotatory drive to the rotatory input of the mechanical drive system. A rotatory load is provided to apply a rotatory load force to the mechanical system. A second drive coupler transmits and receives torque from the rotatory load means to the differential gear set shaft of the mechanical drive system. 
   In one embodiment of the invention, the second drive coupler is provided with a load shaft having a load shaft termination for entering the mechanical drive system and engaging with the differential gear set shaft. The load shaft termination is provided with a fork-like termination distal from the rotatory load, the fork-like termination having first and second axially parallel protuberances, whereby the differential gear set shaft is accommodated therebetween during the engagement. 
   There is further provided an engagement arrangement for securing 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 being 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 a further embodiment of the invention, the mechanical drive system 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 drive 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 being 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. In a practical embodiment of the invention, the pair of meshed elements is provided with a pinion gear and a ring gear. 
   A first acoustic sensor is arranged at a first location in the vicinity of the mechanical drive system for producing a first signal responsive substantially to a qualitative condition of the meshed engagement between the pinion gear and the ring gear. The qualitative condition of the meshed engagement between the pinion gear and the ring gear is responsive to a qualitative condition of respective first gear tooth surfaces of the pinion gear and the ring gear. A second acoustic sensor arranged at a second location in the vicinity of the mechanical drive system for producing a second signal responsive substantially to a qualitative condition of respective second gear tooth surfaces of the pinion gear and the ring gear. 
   In accordance with a further aspect of the invention, there is provided an arrangement for coupling a load to a mechanical drive system for a vehicle while the mechanical drive system is subjected to a testing process. The mechanical drive system is of the type having a rotatory input, at least two rotatory outputs, and a differential gear set arranged on a differential gear set shaft. In accordance with the invention, there is provided a rotatory load and a load shaft arranged to be coupled at a first end thereof to the rotatory load. The load shaft is adapted to be engaged at a second end thereof to the differential gear set shaft. 
   In one embodiment of this further aspect of the invention, the load shaft is provided with a fork-like termination distal from the rotatory load, the fork-like termination having first and second axially parallel protuberances, whereby the differential gear set shaft is accommodated therebetween during the engagement. 
   A rotatory drive applies a rotatory drive force to the rotatory input of the mechanical drive system. Additionally, a first drive coupler transmits and receives torque to and from the rotatory drive to the rotatory input of the mechanical drive system. In a preferred embodiment, the mechanical drive system contains a pinion gear and a ring gear, each having a plurality of gear teeth thereon, the gear teeth each having first and second gear tooth surfaces for communicating with the other 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. 
   In accordance with a method aspect of the invention, there is provided a method of testing a gear assembly of the type having a rotatory input, at least two rotatory outputs, and a differential gear set arranged on a differential gear set shaft. The method includes the steps of:
         installing the gear assembly on a mounting arrangement that resiliently permits motion of the gear assembly in all directions, and that has a resilient frequency characteristic that excludes all natural frequencies of the gear assembly;   applying a torque at the input of the gear assembly, whereby the gear assembly is rotatably operated;   applying a load at the differential gear set shaft of the gear assembly; and   sensing a predetermined operating characteristic of the gear assembly.       

   In one embodiment of this method aspect of the invention, there is provided the further step of detecting acoustic energy issued by the differential gear set shaft of the gear assembly. 
   In further embodiments there are selectably provided the steps of:
         determining a qualitative condition of a pinion and ring gear assembly in the gear assembly under test;   detecting acoustic energy is provided with the further step of detecting vibratory displacement energy issued by the gear assembly; and   monitoring a variation in temperature over time of the gear assembly.       

   In accordance with a further apparatus aspect of the invention, there is provided a torque sensor interposed between the rotatory drive and the mechanical drive system. The torque sensor produces a signal that is responsive to a torque applied by the rotatory drive to the mechanical drive system. Preferably, the torque sensor is arranged to produce a static torque signal that is responsive to the magnitude of torque required to initiate rotatory motion in the mechanical drive system. Additionally, the torque sensor produces a dynamic torque signal that is responsive to the magnitude of torque required to maintain rotatory motion in the mechanical drive system. The torque sensor is provided with a torque-transmitting element that has a predetermined deformation characteristic. The torque-transmitting element becomes deformed in response to the torque applied by the rotatory drive system to the mechanical drive system. A strain sensor is coupled to the torque-transmitting element to produce a strain signal that is responsive to the predetermined deformation characteristic of the torque-transmitting element, and consequently, the applied torque. 
   In a further embodiment, there is provided a sensor that is arranged to communicate with the mechanical drive system for producing an information signal that is responsive to an operating characteristic of the mechanical drive system in response to the rotatory drive force. A further sensor communicates with the mechanical drive system for producing a further information signal that is responsive to a further operating characteristic of the mechanical drive system in response to the rotatory drive force. The operating characteristic and the further operating characteristic of the mechanical drive system correspond, in a highly advantageous embodiment of the invention, to drive and coast operating modes in response to a direction of torque of the rotatory drive force. As previously stated, the sensor in one embodiment is arranged to be translatable between a first position distal from the mechanical drive system, and a second position where the sensor communicates with the mechanical drive system. 
   In this further apparatus aspect, the sensor may be provided with a microphone that is responsive to an acoustic energy issued by the mechanical drive system in response to the rotatory drive force. In another embodiment, the sensor is provided with an accelerometer, or with a velocity sensor. In other embodiments, the sensor is installed on the engagement arrangement, and is translatable therewith between the respective first and second positions. 
   In some arrangements, the sensor is a non-contact sensor that produces a displacement signal that is responsive to displacement of the mechanical drive system in response to the rotatory drive force. Such a non-contact sensor may be a laser sensor for communicating optically with the mechanical drive system. Additionally, the non-contact sensor produces a thermal signal that is responsive to a temperature of the mechanical drive system, such as an infrared sensor that communicates optically with the mechanical drive system. As previously noted, in one specific illustrative embodiment of the invention, the thermal sensor means has a directional characteristic and is directed to a predetermined region of the energy transfer system for determining a rate of change of temperature of the predetermined region with respect to time. In this embodiment, there is provided an acoustic sensor sensitivity control arrangement that is responsive to the thermal sensor for varying the amplitude of a noise signal in response to temperature. The variation of the amplitude of the noise signal with respect to temperature is performed in accordance with a non-linear amplitude-temperature relationship. The variation in temperature over time is useful to indicate low lubricant level, low lubricant quality, or low bearing quality. 
   In a further embodiment, the isolation support is provided with a resilient support element for supporting the mechanical drive system, and is provided with a resilience frequency characteristic that excludes a natural frequency of the mechanical drive system. Additionally, the resilience frequency characteristic of the resilient support element excludes a natural frequency of the drive coupler. 
   In a mechanical embodiment of the invention, there is 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. 
   The engagement driver is provided, in one embodiment, with a linear actuator that has a first end coupled to the base, and a second end coupled to the engagement arrangement. An engagement coupler is interposed between the engagement arrangement and the engagement driver. The engagement coupler is provided with a support portion installed on the isolation support, and first and second engagement arms pivotally coupled to the support portion. Additionally, first and second articulated members are coupled at a pivot point to one another and to the linear actuator. They further are pivotally coupled at distal ends thereof to respective ones of the first and second engagement arms, whereby the linear actuator urges the pivot point along a linear path to a latching position beyond where the first and second articulated members are axially parallel. As previously noted, a resilient biasing arrangement that is installed on at least one of the first and second engagement arms applies a resilient biasing force to the energy transfer system. The resilient biasing arrangement applies a resilient biasing force that maintains the engagement arrangement in the second position. 
   In accordance with a further 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:
         installing the gear assembly on a mounting arrangement that resiliently permits motion of the gear assembly in all directions, and that has a resilient frequency characteristic that excludes all natural frequencies of the gear assembly;   applying a torque at the input of the gear assembly, whereby the gear assembly is rotatably operated;   applying a load at the output of the gear assembly; and   sensing a predetermined operating characteristic of the gear assembly.       

   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 in the vicinity of the gear assembly. 
   In a further embodiment, the step of sensing is provided with the step of detecting vibratory displacement energy issued by the gear assembly. The step of detecting vibratory displacement energy issued by the gear assembly is provided with the further step of effecting communication between an accelerometer and the gear assembly, and the step of detecting vibratory displacement energy issued by the gear assembly is provided with the further step of effecting communication between a velocity sensor and the gear assembly. 
   After performing the step installing there is further provided the step of clamping the gear assembly to the mounting arrangement. In an embodiment where the mounting arrangement is installed on a reference base portion, the step of clamping is performed in response to the further step of applying a clamping actuation force to a clamping arrangement with respect to the reference base portion. A clamping actuation force is applied, and the gear arrangement is enabled to move freely independent of the reference base portion. 
   In a further embodiment, the step of applying a clamping force is provided with the further step of applying a resilient clamping force to the gear assembly. This step may, in certain embodiments, include the further step of monitoring a predetermined dimension of the gear assembly in response to the step of clamping. This is accomplished by use of a sensor that measures distance traveled. 
   Sensing is effected by monitoring a first sensor that receives acoustic energy that is responsive to a qualitative condition of the gear assembly in a drive mode of operation. When the drive mode of operation is in a first direction of operation, the qualitative condition of the gear assembly in the drive mode of operation includes a qualitative condition of a first surface of the teeth of the gear assembly. Also when drive mode of operation is in a first direction of operation, the qualitative condition of the gear assembly in the drive mode of operation includes a qualitative condition of a profile of a gear of the gear assembly, and a qualitative condition of the eccentricity of a gear of the gear assembly. Additionally, the qualitative condition of the gear assembly in the drive mode of operation includes a qualitative condition of the angular orientation of the gears of the gear assembly. In still further embodiments of the method aspect of the invention, wherein the drive mode of operation is in a first direction of operation, the qualitative condition of the gear assembly in the drive mode of operation includes a qualitative condition of a plurality of moving components of the gear assembly. 
   In a further embodiment of the invention, the step of sensing is provided with the further step of monitoring a second sensor that receives acoustic energy that is responsive to a qualitative condition of the gear assembly in a coast mode of operation. The coast mode of operation includes a qualitative condition of a second surface of the teeth of the gear assembly. When the coast mode of operation is in a first direction of operation, the qualitative condition of the gear assembly in the coast mode of operation includes a qualitative condition of a profile of a gear of the gear assembly. Additionally, the qualitative condition of the gear assembly in the coast mode of operation includes a qualitative condition of the eccentricity of a gear of the gear assembly, as well as the angular orientation of the gears of the gear assembly. In further embodiments, the coast mode of operation includes a qualitative condition of a plurality of moving components of the gear assembly. 
   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 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. 
   In accordance with a clamping aspect of the present invention, there is provided an arrangement for clamping a workpiece to a resilient support element. In this aspect of the invention, there is provided a support base installed on the resilient support element. First and second clamping arms are each coupled to the support base by a respective first pivot coupling and arranged to rotate pivotally about the respective first pivot couplings between respective clamped and released counter rotational positions. Each of the first and second clamping arms is further provided with a respective second pivot coupling. First and second links are included in the combination, each having a respective central axis between a respective first pivot coupling where the first and second links are pivotally coupled to one another, and respective second pivot couplings where each of the first and second links is coupled to a second pivot coupling of a respectively associated one of the first and second clamping arms. A drive arrangement urges the first and second links from a first angulated link position corresponding to the released counter rotational position of the first and second clamping arms to a second angulated link position on the other side of a coaxial position of the first and second links, the second angulated link position corresponding to the clamped counter rotational position of the first and second clamping arms. Also, a drive coupler is arranged to couple the drive arrangement to at least one of the first and second links whereby the drive arrangement is decoupled from the first and second links when the links are in the second angulated link position. 
   In one embodiment of the clamping aspect of the invention, the drive coupler is coupled to the first pivot couplings of the first and second links. In an embodiment where the workpiece has a vibratory displacement characteristic, the clamping arrangement is substantially freely displaceable in response to the vibratory displacement characteristic of the workpiece while the first and second links are in the second angulated link position. 
   A sensor is installed on at least one of the first and second clamping arms for detecting a predetermined operating characteristic of the workpiece. The sensor may detect a displacement of the workpiece, or an acoustical energy issued by the workpiece. 
   In an embodiment where the workpiece is a gear assembly having a rotatory input and an output, there is additionally provided a rotatory drive for applying a torque at the rotatory input of the gear assembly. Also, a drive coupler couples the rotatory drive to the rotatory input of the gear assembly. The drive coupler is arranged to provide substantially only torque to the gear assembly at its rotatory input, without any substantial axial loading, and to attenuate the propagation of acoustic energy from the rotatory drive arrangement. A load is coupled to the output of the gear assembly, the load being arranged to simulate an actual operating condition of the gear assembly. 
   In accordance with a drive coupling aspect of the invention, substantially exclusively torque is transmitted from a drive arrangement to a gear assembly under test. The drive coupling arrangement includes a first coupler portion attached to the drive coupling arrangement, 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. A second coupler portion is provided and has an internal cross-sectional configuration that accommodates the polygonal cross-sectional configuration of said first coupler portion. The second coupler portion is provided with a plurality of engagement portions that communicate exclusively with a predetermined number of the substantially planar surfaces of said first coupler portion. The first and second coupler portions are axially translatable along said first coupler portion for a portion of the predetermined length of axis. Therefore, the torque is transmitted between the first and second coupler portions without exerting an axial load. 
   In one embodiment of this drive coupling aspect of the invention, the polygonal cross-sectional configuration corresponds to a hexagon. Also, the second coupler portion has three engagement portions that engage three respective planar surfaces of the first coupler portion. 
   In accordance with a further method aspect of the invention, there is provided a method of signal analysis for processing information from a gear system under test. This further method aspect includes the steps of:
         driving the gear system under test by application of a rotatory input;   producing a first signal responsive to the torque applied to the gear system under test;   producing first digital data responsive to a first correlation between the first signal and time;   measuring peaks in said first digital data to determine whether the peaks exceeds a predetermined threshold magnitude; and   first subjecting those of the peaks that exceed the predetermined threshold magnitude to harmonic analysis.       

   In a specific illustrative embodiment of the invention of this further method aspect, there is provided the further step of comparing the result of the harmonic analysis of the step of first subjecting against gear tooth harmonics to determine whether the peaks constitute an anomaly. Such an anomaly is a bump or a nick on a tooth of the gear system under test. 
   In a highly advantageous embodiment of the invention wherein improved results are obtained, there are provided the further steps of:
         producing a second signal responsive to a noise produced by the gear system under test in response to the step of driving;   producing a second digital data responsive to a second correlation between the second signal and time;   identifying peaks in the second digital data that are simultaneous with peaks in said first digital data;   measuring the simultaneous peaks in the second digital data to determine whether they exceed a second predetermined threshold magnitude; and   second subjecting those of the simultaneous peaks in the second digital data that exceed the second predetermined threshold magnitude to harmonic analysis.       

   As is the case in the embodiment where only the torque signal is subjected to harmonic analysis, there is additionally provided in this embodiment the further step of comparing the result of the harmonic analysis of the steps of first subjecting and second subjecting against gear tooth harmonics to determine whether the simultaneous peaks constitute an anomaly. Thus, in this embodiment, the torque and the noise signals are subjected to harmonic analysis. It is desired in an embodiment of the invention that is used to test gear systems, to determine whether the anomaly is a bump or a nick on a tooth of the gear system under test. In a further step of calculating, the severity of the anomaly determined in the step of comparing is determined. 
   In a still further embodiment of this method aspect, there are provided the further steps of:
         establishing predetermined harmonic criteria; and   determining whether the results of the analysis in the step of subjecting conforms to the predetermined harmonic criterial of the step of establishing.       

   In accordance with a still further method aspect of the invention, there is provided a method of signal analysis for processing information from a gear system under test for determining the presence of bumps or nicks therein. In this still further method aspect, there are provided the steps of:
         driving the gear system under test by application of a rotatory input;   producing a first signal responsive to the torque applied the gear system under test;   producing a second signal responsive to a noise produced by the gear system under test in response to the step of driving;   producing first digital data responsive to a first correlation between the first signal and time;   producing a second digital data responsive to a second correlation between the second signal and time;   identifying simultaneous peaks in the first and second digital data;   measuring the simultaneous peaks in the first and second digital data to determine whether they exceed a predetermined threshold magnitude; and   subjecting those of the simultaneous peaks that exceed the predetermined threshold magnitude to harmonic analysis.       

   In one embodiment of this method aspect, there is provided the further step of comparing the result of the harmonic analysis of the step of subjecting against gear tooth harmonics to determine whether the simultaneous peaks constitute an anomaly. In a further embodiment, there is provided the further step of calculating the severity of the anomaly of the step of comparing. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     Comprehension of the invention is facilitated by reading the following detailed description, in conjunction with the annexed drawing, in which: 
       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; 
       FIG. 2  is a side plan view of the embodiment of  FIG. 1 ; 
       FIG. 3  is an exploded plan representation of the embodiment of  FIG. 1  showing certain drive components; 
       FIG. 4  is a top plan view of the embodiment of  FIG. 1 ; 
       FIG. 5  is a partially phantom front plan view of a drive arrangement that supplied rotatory mechanical energy to an isolate mechanical energy transfer system under test; 
       FIG. 6  is side plan view of the drive system of  FIG. 5 ; 
       FIG. 7  is a side plan representation of the drive system as shown in  FIG. 6 , enlarged to show greater detail; 
       FIG. 8  is a side plan view of a coupler that couples the drive system to the mechanical system under test; 
       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; 
       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; 
       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; 
       FIG. 12  is a partially cross-sectional side plan view of the compact drive arrangement of  FIG. 11  further showing a resilient coupling element; 
       FIG. 13  is a partially phantom enlarged representation of the resilient coupling element shown in  FIG. 12 ; 
       FIG. 14  is a simplified schematic, fragmented representation of a load shaft arrangement constructed in accordance with the principles of the invention for applying torque to a differential gear set shaft; 
       FIG. 15  is a schematic plan cross-sectional representation of the load shaft arrangement of  FIG. 14  installed in a differential axle arrangement; 
       FIG. 16  is a simplified schematic plan representation of a test arrangement constructed in accordance with the present invention showing the load shaft arrangement implemented so as to permit testing of the engagement between the pinion and ring gear, without interference from the differential gear set, the testing be effected from only one side of the axle under test; 
       FIG. 17  is a process diagram of a typical process for conducting an energy analysis; 
       FIG. 18  is a process diagram of a process for conducting an energy analysis in accordance with the principles of the present invention; and 
       FIG. 19  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. 
   

   DETAILED DESCRIPTION 
     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). 
   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 . 
     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 . 
     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. 
     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 . 
   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 . 
     FIG. 2  additionally shows a drive motor  40 , which in this embodiment, is coupled to a belt pulley  42 , shown in FIG.  1 . 
     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 . 
     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. 
   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. 
     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 . 
     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 . 
   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. 
   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 . 
   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. 
     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 . 
     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 ′. 
     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. 
   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. 
     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. 
   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 . 
   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 . 
   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 ′. 
   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. 
     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 . 
   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. 
   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. 
   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. 
   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. 
     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 . 
     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 there around. 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 . 
   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 a 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. 
     FIG. 14  is a simplified schematic, fragmented representation of a load shaft arrangement  260  constructed in accordance with the principles of the invention for applying torque to a differential gear set shaft  261 . Load shaft arrangement  260  has a first end  264  coupled via a shaft portion  265  to a differential gear set shaft engagement portion  266 . As shown, differential gear set shaft engagement portion  266  is formed of a fork-like termination having axially extending protuberances  270  and  271 . The differential gear set shaft engagement portion therefore is enabled to apply a transaxial torque via axially extending protuberances  270  and  271  to differential gear set shaft  261 . 
   Shaft portion  265  has a diameter dimension that is smaller that the splines (not shown) that conventionally are provided to extend radially inward of the central aperture of differential bevel gear  273 , which is one of the gears in the differential gear set (not shown in this figure). In one embodiment, the diameter of shaft portion  265  is approximately 1.25″. An O-ring  274  prevents noise that would result from metal-to-metal communication between shaft portion  265  and differential gear set carrier  277 . 
     FIG. 15  is a schematic plan cross-sectional representation of the load shaft arrangement of  FIG. 14  installed in differential axle arrangement  11 . In this figure, differential  11  is shown to have a pinion gear  280  that is coupled via a pinion shaft  281  to hexagonal shaft  69 . Pinion gear  280  is meshed, in a conventional manner, with a ring gear  284 . Load shaft arrangement  260  is, in this specific illustrative embodiment of the invention, inserted into rotatory output  14  of differential  111  and through the center of ring gear  284  to engage differential gear set shaft  261  via fork-like protuberances  270  and  271 . It is evident from  FIGS. 14 and 15  that load shaft arrangement  260  can be inserted into either of rotatory outputs  14  or  15 , i.e., ring gear side or differential gear set side, as required by the particular application. The application of a load at load shaft arrangement  260  ensures that ring gear  284  is rotated synchronously with the differential gear set, thereby ensuring that the gears of the differential gear set are not rotating with respect to each other. Thus, the practice of the present invention obviate the need to employ synchronous loads at each of rotatory outputs  14  and  15 . 
     FIG. 16  is a simplified schematic plan representation of an automated test arrangement  300  constructed in accordance with the present invention showing load shaft arrangement  260  implemented so as to permit noise testing of the engagement between pinion  280  and ring gear  284 , without incurring interfering noise from the differential gear set. Moreover, the testing is effected from only one side of differential  11  under test. Elements of structure that have previously been discussed are similarly designated. 
   In this automated specific illustrative embodiment of the invention, differential  11  has previously been deposited onto pallet  309 , specifically pallet supports  310  and  311  thereon. In this production embodiment of the invention, pallet  309  arrives to be tested at test arrangement  300  by translation along rollers  313 . 
   An overhead lift arrangement  302 , which is additionally shown in the figure in phantom in the raised position, is vertically displaceable along an overhead slide  303 . Once the differential has been delivered thereunder, the overhead lift arrangement lowers a test head  314  to the vicinity immediately over differential  11 . In some embodiments of the invention, little or no motion of overhead lift arrangement  302  is required, depending upon the size of ring gear  284  of differential  11 . Latching arrangements  316  and  317  engage differential  11  and raise same a small amount over supports  310  and  311 . Such a raising of the differential in this embodiment, may be on the order of ¼ inch, and is represented in the figure by the phantom outline (not specifically identified) on each side of differential  11 . The differential, upon being lifted off of supports  310  and  311 , hangs from overhead lift arrangement  302  via resilient supports  319  and  320 , which permit freedom of movement of the differential during the application of rotatory input via nut driver  70  (shown schematically in this figure), as previously described hereinabove with respect to  FIGS. 7-9 . In addition, the lifting avoids transmission of assembly line noises to the differential via supports  310  and  311 . Engagement is achieved with hexagonal nut  69  (not shown in this figure) by raising drive motor  40  and its associated structure, including coupling shaft  62 , along drive slide  306 . Load shaft arrangement  260  is then inserted into one of the rotatory outputs of the differential by sliding load motor  81  along a motor slide  305 . Freedom of motion of the differential is not restricted by load shaft arrangement  260 , as this shaft is coupled to load shaft  95  via a resilient coupler  322 . 
     FIG. 17  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 . 
   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/D 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. 
   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 . 
     FIG. 18  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 . 
   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. 
   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 . 
     FIG. 19  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 . 
   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. 
   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. 
   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 . 
   In one embodiment of the process of  FIG. 19 , 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. 
   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. 
   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 . 
   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.