Apparatus, system and method for tribo-dynamic measurements

Abstract

An apparatus, system and method for use in performing tribo-dynamic measurements is disclosed. In certain examples, there is provided an apparatus comprising: coupling means configured to selectively releasably couple a prime mover to a rotatable structure of a tribological testing apparatus for performing a tribo-dynamic measurement on a test component; wherein the coupling means is configurable in each of: a coupled state in which the rotatable structure is engaged with the prime mover to enable rotation of the rotatable structure to be driven via the prime mover, and a de-coupled state in which the rotatable structure is disengaged from the prime mover to enable the rotatable structure to rotate independently of the prime mover.

Description

[0001] APPARATUS, SYSTEM AND METHOD FOR TRIBO-DYNAMIC MEASUREMENTS

[0002] TECHNOLOGICAL FIELD

[0003] Examples of the present disclosure relate to an apparatus, system and method for use in performing tribo-dynamic measurements.

[0004] BACKGROUND

[0005] It is common practice to characterise structures / physical components (e.g. one or more components of rotating machinery) using modal testing statically. However, this neglects the influence of tribological phenomenon such as lubrication films which influence rotating machinery / component’s dynamic properties significantly (not least stiffness and damping properties of rotating lubricated-bearing-shaft conjunctions such a roller bearing elements).

[0006] A rotating component such as a rolling element bearing requires a lubricant film within a contact between an inner / outer race and constituent rolling elements. Such a film supports a radial load, reduces friction, and increases durability of the individual rolling elements and raceways. The lubricant is entrained into the contact at a velocity that is the average of two surface velocities (inner / outer bearing raceway velocity and rolling element tangential velocity). With increasing entrainment speed, the lubricant’s central film thickness increases. The increase in film thickness increases the radial load within the rolling element contact. This increase in radial load causes an increase in localised surface elastic deformation to raceways and rolling elements. Accordingly, a consequence of the increased film thickness in a rolling element bearing (which increases with increase rotational speed) is that it alters the stiffness and damping properties of the rolling element bearing. In other words, a rolling element bearing’s stiffness and damping value changes / increases with increasing rotational speed of the rolling element bearing. Moreover, stiffness and damping values alter dynamic characteristics of the rolling element bearing such as shifting its resonant frequencies - which can effect its durability and efficiency. Tribological characterisations of pairings of lubricants, bearings, and shafts can be useful for Noise Vibration and Harshness refinement or rotational structures and components.

[0007] It is desirable to perform a tribological assessment / test of a physical component (such as a roller element bearing) to determine its tribological properties. Moreover, it is desirable to perform dynamic (i.e. non-static) tribological assessments / tests of a physical component (such as a roller element bearing) to determine its tribological properties in motion / during use - i.e. to perform tribo-dynamic measurements to determine the physical component’s tribo-dynamic properties. Conventional systems for performing a tribological assessment of a physical component (such as a roller element bearing) to analyse durability and efficiency of the component are not always optimal.

[0008] Conventionally, in order to analyse a rolling element bearing’s dynamic and tribological performance (e.g. to perform a tribo-dynamic measurement to characterise a stiffness / damping of the roller element bearing), impulse testing of a rotatable structure / component is carried out whilst the rotatable structure / component is rotating. For instance, a user would manually hit a rotating shaft, to which the rotatable structure / component (such as a roller element bearing) is coupled and hence which itself is also rotating, with an impulse hammer or modal hammer; whilst the shaft is coupled to and being rotatably driven via a prime mover rotation driving means / device.

[0009] In some circumstances it can be desirable to provide an apparatus for improving tribo- dynamic measurements, such as modal testing of rotating structures, components, devices or machinery. In some circumstances it can be desirable to provide an apparatus for improving the accuracy of tribo-dynamic measurements.

[0010] The listing or discussion of any prior-published document or any background in this specification should not necessarily be taken as an acknowledgement that the document or background is part of the state of the art or is common general knowledge. One or more aspects / examples of the present disclosure may or may not address one or more of the background issues.

[0011] BRIEF SUMMARY

[0012] The scope of protection sought for various embodiments of the invention is set out by the claims.

[0013] According to various, but not necessarily all, examples of the disclosure there are provided examples as claimed in the appended claims. Any examples and features described in this specification that do not fall underthe scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention.

[0014] According to at least some examples of the disclosure there is provided an apparatus comprising: coupling means configured to selectively releasably couple a prime mover to a rotatable structure of a tribological testing apparatus for performing a tribo-dynamic measurement on a test component; wherein the coupling means is configurable in each of: a coupled state in which the rotatable structure is engaged with the prime mover to enable rotation of the rotatable structure to be driven via the prime mover, and a de-coupled state in which the rotatable structure is disengaged from the prime mover to enable the rotatable structure to rotate independently of the prime mover.

[0015] According to at least some examples of the disclosure there is provided a system comprising: the apparatus as mentioned above; the prime mover; and the rotatable structure.

[0016] According to various, but not necessarily all, examples of the disclosure there is provided a method of performing one or more tribo-dynamic measurements on a rotatable test component, the method comprising: coupling a prime mover to a rotatable test component; driving rotation of the rotatable test component via the coupled prime mover; decoupling the prime mover from the rotating test component; and performing one or more measurements on the decoupled rotating test component.

[0017] According to various, but not necessarily all, examples of the disclosure there is provided a method of providing and / or manufacturing an apparatus and / or system as described herein.

[0018] According to various, but not necessarily all, examples of the disclosure there is provided a method of using an apparatus and / or system as described herein.

[0019] The following portion of this 'Brief Summary’ section describes various features that can be features of any of the examples described in the foregoing portion of the 'Brief Summary’ section. The description of a function should additionally be considered to also disclose any means suitable for performing that function.

[0020] In some but not necessarily all examples, the coupling means comprises a clutch.

[0021] In some but not necessarily all examples, the coupling means is configured such that, in the de-coupled state, movement of the rotatable structure is independent of movement of the prime mover.

[0022] In some but not necessarily all examples, the coupling means is configured as a component of a drive train between the prime mover and the rotatable structure.

[0023] In some but not necessarily all examples, the rotatable structure is a rotatable shaft of the tribological testing apparatus and wherein the test component is coupled to the rotatable shaft. In some but not necessarily all examples, the test component is a rolling element bearing.

[0024] In some but not necessarily all examples, the apparatus is embodied in a module.

[0025] While the above examples of the disclosure and optional features are described separately, it is to be understood that their provision in all possible combinations and permutations is contained within the disclosure. It is to be understood that various examples of the disclosure can comprise any or all of the features described in respect of other examples of the disclosure, and vice versa. Also, it is to be appreciated that any one or more or all of the features, in any combination, may be implemented by / comprised in / performable by an apparatus, a method, and / or computer program instructions as desired, and as appropriate.

[0026] BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Some examples will now be described with reference to the accompanying drawings in which:

[0028] Fig. 1 schematically shows an example of an apparatus, in a coupled state, according to the present disclosure;

[0029] Fig. 2 schematically shows an example of an apparatus, in a de-coupled state, according to the present disclosure; and

[0030] Fig. 3 schematically shows an example of a system according to the present disclosure.

[0031] The figures are not necessarily to scale. Certain features and views of the figures can be shown schematically or exaggerated in scale in the interest of clarity and conciseness. For example, the dimensions of some elements in the figures can be exaggerated relative to other elements to aid explication. Similar reference numerals are used in the figures to designate similar features. For clarity, all reference numerals are not necessarily displayed in all figures.

[0032] In the drawings (and description) a similar feature may be referenced by the same three- digit number.

[0033] DETAILED DESCRIPTION

[0034] Fig. 1 schematically illustrates, and the following description describes, an example of an apparatus 100 according to the present disclosure.

[0035] The apparatus 100 comprises coupling means 101 configured to selectively releasably couple a prime mover 102 to a rotatable structure 103 of a tribological testing apparatus 300 for performing a tribo-dynamic measurement on a test component 104. In this example, the test component 104 corresponds to one or more bearings via which the rotatable structure 103 (i.e. "shaft 2”) is supported. The coupling means is configurable in each of: a coupled state (see Fig. 1 ) in which the rotatable structure is engaged with the prime mover to enable rotation of the rotatable structure to be driven via the prime mover, and a de-coupled state (see Fig. 2) in which the rotatable structure is disengaged from the prime mover to enable the rotatable structure to rotate independently of the prime mover.

[0036] Fig. 1 schematically illustrates the apparatus 100 and coupling means 101 in a coupled state, wherein shaft 1 (connected to the prime mover 102) is coupled to shaft 2 (supported by bearings 104) via the coupling means 101. In the coupled / engaged state, an angular velocity of the rotatable structure 103 (i.e. "shaft 2”) is dependent on an input angular velocity from the prime mover (i.e. an input angular velocity from a shaft "shaft 1 ” connected to the prime mover). Accordingly, the input angular velocity of the prime mover will rotate shaft 1 and shaft 2 at the same / similar angular velocities.

[0037] Fig. 2 schematically illustrates the apparatus 100’ and coupling means 101 ’ in a decoupled state, wherein the angular velocity of the rotatable structure 103 ("shaft 2”) is independent on the input angular velocity from the prime mover (i.e. the input angular velocity from the shaft "shaft 1 ” connected to the prime mover). Once shaft 2, which is supported by the bearing / bearings 104 of interest, has been accelerated to a first pre-determined / desired angular velocity, shaft 2 can be decoupled / disengaged from shaft 1 , following which a tribodynamic test (e.g. a modal / impulse test) can be conducted / performed. When the decoupled shaft system has decelerated (e.g. due to friction) to a second pre- determined / desired angular velocity, a second tribo-dynamic test (e.g. a second modal / impulse test) can be conducted. The results can then be averaged if necessary / appropriate.

[0038] The coupling means may be implemented by any suitable mechanism or means. The coupling / de-coupling functionality could be achieved via mechanical or electromechanical means. In some examples, the coupling means comprises or is a clutch / clutch assembly - for instance such as an electro-magnetic clutch that enables dis-engagement of the prime mover from the rotatable structure in a smooth manner.

[0039] As used herein, the term prime mover can be a rotation driving device / assembly and can used to denote any suitable mechanism or means for driving a rotation of the rotatable structure. The rotation may be effected via any suitable mechanism or means, not least such as electromagnetic means, compressed air and a propellor. In some examples, the prime mover comprises or is an electric motor. In some examples, the prime mover is an assembly / system (including at least a part of a drive train) via which torque is transmitted and which causes the rotatable structure to rotate. In some examples, the rotatable structure is or comprises a shaft to which the test component is attached / mechanically coupled.

[0040] In some examples, the test component is or comprises one or more bearings for supporting the shaft. In some examples, the test component is a rotatable device or a piece of rotatable machinery. For instance, the test component may be or comprise the rotatable structure and / or one or more bearings (e.g. roller element bearings) attached thereto for supporting the rotatable structure. Roller element bearings support a radial load and permit rotation in a multitude of mechanical systems, including: vehicle transmissions, electric motors, wind turbines and manufacturing equipment.

[0041] In some examples, the tribo-dynamic measurement on the test component comprises a dynamic modal test to measure stiffness and damping of the test component.

[0042] In some examples, the prime mover is configured to indirectly drive rotation of the rotatable component. In some examples, the prime mover is configured to drive rotation of the rotatable test component indirectly via one or more of: a drive train, a shaft, a coupling, and a torque transducer.

[0043] In some examples, the coupling means is a part is a drive train between the prime mover and the rotatable structure. In some examples, the coupling means is disposed at or proximal to a distal end of the drive train (i.e. at an end distal to the distal to the prime mover) such that, not only is the rotatable structure isolated from the prime mover, it is also isolated from the remaining "downstream” parts and components of the drive train (e.g. not least one or more couplings or a torque transducer between the coupling means and the prime mover) via which the rotatable structure is indirectly driven.

[0044] When conducting modal testing or force transmissibility testing it is desirable to not add mass or stiffnesses to the rotatable structure / test component under investigation. This is because the stiffness and damping of the structure / test component will vary according to the change of mass and additional material on the system, which affects the modal behaviour.

[0045] Conventionally, when conducting tests on a bearing test rig, typically system dynamics that includes the prime mover are not of interest and moreover they also unnecessarily influence the results of tribo-dynamic measurements on conjunctions (e.g. measurements / characterisation of bearing-shaft-lubricant conjunction dynamic characteristics). In order to obtain a more accurate representation of such conjunctions, they should be isolated from additional mass that peripheral devices (prime mover, couplings, drive train) provide. Advantageously, in examples of the disclosure, the coupling means enables the rotatable structure to be selectively: coupled / engaged with the prime mover so as to be driven thereby and wherein rotation of the rotatable structure is dependent upon rotation of the prime mover (or the prime mover’s spindle or a transmission shaft) such that they co-rotate, and decoupled / disengaged from the prime mover such that rotation of the rotatable structure is independent of rotation of the prime mover (or the prime mover’s spindle or the transmission shaft), thereby enabling the rotatable structure to rotate freely of the prime mover (or the prime mover’s spindle or the transmission shaft) and, in effect, be rotationally isolated from prime mover (or the prime mover’s spindle or the transmission shaft).

[0046] In addition to enabling the rotatable structure to rotate independently of the prime mover, the coupling means may also be configured to enable the rotatable structure to move independently of the prime mover. For instance, translational movement (e.g. along an axial direction) of the rotatable structure is independent of translational movement of the prime mover (and correspondingly, translational movement of the prime mover is independent of translational movement of the rotatable structure such that the rotatable structure is mechanically / movably isolated from the prime mover so that movement of the prime mover does not cause induce movement on the rotatable structure).

[0047] Such free rotation / rotational isolation from the prime mover (as well as being mechanically isolated / isolated from translational movement of the prime mover and other components of the drive train 'upstream’ of the coupling means) enables improved performance of tribodynamic measurements (e.g. modal testing or force transmissibility testing) on the test component (e.g. bearing), such as a more accurate characterisation of bearing behaviour e.g. stiffness and damping values. Moreover, since stiffness and damping values alter dynamic characteristics of a bearing (such as shifting its resonant frequencies), this cab effect the durability and efficiency of the bearing. Improved tribological measurements / characterisations of pairings of lubricants, bearings, and shafts of a conjunction can thereby be useful for noise vibration and harshness refinement of rotational structures and components of the conjunction - particular at higher speeds (e.g. above 4,000 or 8,000 rpm) where an increase of stiffness of a lubricated bearing conjunction is more significant.

[0048] Fig. 3 shows an example of a tribo-dynamic test rig 300 according to the present disclosure. In this example, the system is setup for a specific application, namely dynamic characteristic testing of one or more test components - in this example bearings 104.

[0049] In the system, a rotatable structure (i.e. a shaft 103), supported by test components (i.e. bearings 104), is connected to a prime mover (i.e. spindle 102) via couplings (including the coupling means 101 as discussed above) and a torque transducer. All of these additional structures, if coupled / engaged to the shaft 103 whilst tribo-dynamic testing was being performed, would influence the measurement data collected and hence would ultimately influence / affect any determined stiffness and damping values of the shaft-lubricant- bearing conjunction. In order to remove the affect of these additional structures, and their masses which are surplus to requirement, the tribo-dynamic test rig system 300 comprises a coupling means 101 that used that provides a de-coupling mechanism as discussed above, not least with respect to Fig. 2.

[0050] The tribo-dynamic test rig 300 allows for accurate tribo-dynamic characterisation of highspeed rolling element bearings and their respective lubricating fluids.

[0051] The test rig comprises a heavy machine bed which is used to mount two bearing blocks, and a loading tower. The bearing blocks support two rolling element bearings, at least one of which corresponds to the test component 104 whose tribo-dynamic properties (e.g. stiffness and damping) are to be characterised. The bearings in turn support a main test shaft 103.

[0052] One end of the main test shaft is left free with no fixture on the end. The other end of the shaft is connected to a first coupling, namely an apparatus 100 comprising the coupling means 101 as disused above. The first coupling / apparatus connects the main test shaft to a torque transducer via another shaft. The torque transducer is then connected to a spindle / rotational prime mover 402 via a second coupling and a yet further shaft.

[0053] A bearing axial preload device applies an axial load to an outer raceway of the bearing(s) under test.

[0054] The load tower helps to support a modal impact hammer and a shaker device. The load tower directly supports a linear rail guide which allows for a mounting bracket to slide freely in one direction, e.g. a vertical direction towards the main shaft. The modal hammer and shaker are both directly connected to the mounting bracket. The mounting bracket can either be moved via a pneumatic or solenoid impulse or shaker.

[0055] A sensor bracket is mounted directly to the bearing block housing. The sensor bracket contains two motion (displacement) sensors 304, e.g. capacitive based sensors, that are aligned perpendicularly with respect to on another.

[0056] The motion sensors measure the motion of the shaft relative to the bearing block housing. One in a direction parallel to the direct excitation of the shaft (e.g. a radial / vertical direction). The other sensor measures the motion perpendicular to the initial excitation (e.g. a horizontal radial direction).

[0057] The torque transducer measures the torque required of the rotational prime mover / motor to rotate the shaft. The modal hammer / shaker accelerometer acquire voltage signals which are passed through a conditioning amplifier and then to a data acquisition device, DAQ. The DAQ in turn passes the information to a computer which reads in the data. The torque transducer motion sensors are also connected to the same DAQ.

[0058] The computer is used to control the shaker / pneumatics / solenoid as well as the spindle / rotational prime mover.

[0059] The bearings may be lubricated via splash / drip lubrication feed via a heated recirculation sump, which can be controlled via a computer.

[0060] There now follows a discussion of a methodology of performing tribo-dynamic measurements / characterisations of a test component (i.e. bearing) using apparatuses and systems in accordance with the present disclosure.

[0061] A test is programmed via a computer. This includes detailing rotor test speeds (i.e. a number of discrete angular velocities of the shaft to test), an amount of axial preload, an impact load required (up to 2.2kN), and a number of repeats required at each test speed / impact load / axial preload required. The computer automatically runs the test without human intervention.

[0062] In each single test: o the computer controls the axial preload applied to the bearings. o the shaft’s angular velocity is controlled via the computer. o when the shaft reaches a pre-determined angular velocity, the shaft is decoupled / disengaged from the prime mover via the coupling means 101 o the computer remotely triggers the impacting means / mechanism. o the modal hammer tip makes an impact directly to the main test shaft itself to excite the system whilst the main test shaft is rotating. o The DAQ continuously captures data from the modal hammer, shaker, motion sensors and torque transducer.

[0063] The system repeats the following steps until the desired programme is complete.

[0064] One data post process method consists of: o a low pass filter is used to remove some of the undesirable noise. o the measured signals are further conditioned to remove extra sources of noise such as run out. o the computer uses software to compute a frequency response of the bearing-shaft-lubricant conjunctions relative to the impact / shaking (the bearing-shaft-lubricant conjunctions corresponding to a joint that comprises of a shaft seated within a bearing where lubrication is present) o the real component of a frequency response function, FRF, equates to the test component’s stiffness o the imaginary term of the FRF equates to the test component’s damping

[0065] Such a methodology and experimental test rig may aid the selection and design of efficient, durable rolling element bearings, such as rolling element bearings that can be found in many industrial applications including but not limited to: automotive, aviation, marine, and power generation applications.

[0066] It is to be noted there are other methods that can also be used that use time domain data and / or a system modelling approach etc.

[0067] Examples of the disclosure may thereby be used on a test rig that automates the process of characterising dynamic attributes of rolling element bearings, up to high speeds (e.g. 20- 30k rpm), with respects to the coupled interactions of tribology.

[0068] In some examples, there is provided a method of performing tribo-dynamic measurements on a rotatable test component, the method comprising: coupling a prime mover to a rotatable test component (e.g. via the coupling means 101 and shaft 103 to which the rotatable test component is attached, for instance wherein the rotatable test component is one or more bearings supporting the shaft); driving rotation of the rotatable test component via the coupled prime mover (e.g. by driving the shaft in a coupled state); decoupling the prime mover from the rotating test component; and performing one or more measurements on the decoupled rotating test component (e.g. by performing a modal impact test on the rotating shaft when in a rotating and decoupled state).

[0069] Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0070] Features described in the preceding description can be used in combinations otherthan the combinations explicitly described.

[0071] Although functions have been described with reference to certain features, those functions can be performable by other features whether described or not.

[0072] Although features have been described with reference to certain examples, those features can also be present in other examples whether described or not. Accordingly, features described in relation to one example / aspect of the disclosure can include any or all of the features described in relation to another example / aspect of the disclosure, and vice versa, to the extent that they are not mutually inconsistent. Although various examples of the present disclosure have been described in the preceding paragraphs, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as set out in the claims. For example, whilst the present disclosure has described examples of characterising roller bearing stiffness and damping during dynamics conditions, examples of the invention could be applied to other types of bearings and other test components. Examples of the invention could be applied to modal testing of rotating devices or machinery. Examples could also be used in full automotive, aeronautical, marine, power generation powertrains and drivetrains, manufacturing assembly lines.

[0073] The term 'comprise’ is used in this document with an inclusive not an exclusive meaning. That is any reference to X comprising Y indicates that X can comprise only one Y or can comprise more than one Y. If it is intended to use 'comprise’ with an exclusive meaning then it will be made clear in the context by referring to "comprising only one ...” or by using "consisting”.

[0074] In this description, the wording 'connect’ and 'couple’ and their derivatives mean operationally connected and coupled. It should be appreciated that any number or combination of intervening components can exist (including no intervening components), i.e. so as to provide direct or indirect connection and coupling.

[0075] In this description, reference has been made to various examples. The description of features or functions in relation to an example indicates that those features or functions are present in that example. The use of the term ’example’ or 'for example’, 'can’ or 'may’ in the text denotes, whether explicitly stated or not, that such features or functions are present in at least the described example, whether described as an example or not, and that they can be, but are not necessarily, present in some or all other examples. Thus 'example’, 'for example’, 'can’ or 'may’ refers to a particular instance in a class of examples. A property of the instance can be a property of only that instance or a property of the class or a property of a sub-class of the class that includes some but not all of the instances in the class.

[0076] In this description, references to "a / an / the” [feature, element, component, means ...] are used with an inclusive not an exclusive meaning and are to be interpreted as "at least one” [feature, element, component, means ...] unless explicitly stated otherwise. That is any reference to X comprising a / the Y indicates that X can comprise only one Y or can comprise more than one Y unless the context clearly indicates the contrary. If it is intended to use 'a’ or 'the’ with an exclusive meaning then it will be made clear in the context. In some circumstances the use of 'at least one’ or 'one or more’ can be used to emphasise an inclusive meaning but the absence of these terms should not be taken to infer any exclusive meaning. As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0077] The presence of a feature (or combination of features) in a claim is a reference to that feature (or combination of features) itself and also to features that achieve substantially the same technical effect (equivalent features). The equivalent features include, for example, features that are variants and achieve substantially the same result in substantially the same way. The equivalent features include, for example, features that perform substantially the same function, in substantially the same way to achieve substantially the same result.

[0078] In this description, reference has been made to various examples using adjectives or adjectival phrases to describe characteristics of the examples. Such a description of a characteristic in relation to an example indicates that the characteristic is present in some examples exactly as described and is present in other examples substantially as described. In the above description, the apparatus described can alternatively or in addition comprise an apparatus which in some other examples comprises a distributed system of apparatus, for example, a client / server apparatus system. In examples where an apparatus provided forms (or a method is implemented as) a distributed system, each apparatus forming a component and / or part of the system provides (or implements) one or more features which collectively implement an example of the present disclosure. In some examples, an apparatus is re-configured by an entity other than its initial manufacturer to implement an example of the present disclosure by being provided with additional software, for example by a user downloading such software, which when executed causes the apparatus to implement an example of the present disclosure (such implementation being either entirely by the apparatus or as part of a system of apparatus as mentioned hereinabove).

[0079] The above description describes some examples of the present disclosure however those of ordinary skill in the art will be aware of possible alternative structures and method features which offer equivalent functionality to the specific examples of such structures and features described herein above and which for the sake of brevity and clarity have been omitted from the above description. Nonetheless, the above description should be read as implicitly including reference to such alternative structures and method features which provide equivalent functionality unless such alternative structures or method features are explicitly excluded in the above description of the examples of the present disclosure.

[0080] Whilst endeavouring in the foregoing specification to draw attention to those features of examples of the present disclosure believed to be of particular importance it should be understood that the applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and / or shown in the drawings whether or not particular emphasis has been placed thereon.

[0081] The examples of the present disclosure and the accompanying claims can be suitably combined in any manner apparent to one of ordinary skill in the art. Separate references to an "example”, "in some examples” and / or the like in the description do not necessarily refer to the same example and are also not mutually exclusive unless so stated and / or except as will be readily apparent to those skilled in the art from the description. For instance, a feature, structure, process, block, step, action, or the like described in one example may also be included in other examples, but is not necessarily included.

[0082] Each and every claim is incorporated as further disclosure into the specification and the claims are embodiment(s) of the present disclosure. Further, while the claims herein are provided as comprising specific dependencies, it is contemplated that any claims can depend from any other claims and that to the extent that any alternative embodiments can result from combining, integrating, and / or omitting features of the various claims and / or changing dependencies of claims, any such alternative embodiments and their equivalents are also within the scope of the disclosure.

Claims

CLAIMSWe claim:

1. An apparatus comprising: coupling means configured to selectively releasably couple a prime mover to a rotatable structure of a tribological testing apparatus for performing a tribo-dynamic measurement on a test component; wherein the coupling means is configurable in each of: a coupled state in which the rotatable structure is engaged with the prime mover to enable rotation of the rotatable structure to be driven via the prime mover, and a de-coupled state in which the rotatable structure is disengaged from the prime mover to enable the rotatable structure to rotate independently of the prime mover.

2. The apparatus of any previous claim, wherein the coupling means comprises a clutch.

3. The apparatus of any previous claim, wherein the coupling means is configured such that, in the de-coupled state, movement of the rotatable structure is independent of movement of the prime mover.

4. The apparatus of any previous claim, wherein the coupling means is configured as a component of a drive train between the prime mover and the rotatable structure.

5. The apparatus of any previous claim, wherein the rotatable structure is a rotatable shaft of the tribological testing apparatus and wherein the test component is coupled to the rotatable shaft.

6. The apparatus of any previous claim, wherein the test component is a rolling element bearing.

7. The apparatus of any previous claim, wherein the apparatus is embodied in a module.

8. A system comprising: the apparatus of any previous claim; the prime mover; and the rotatable structure.

9. The system of claim 8, wherein the prime mover is configured to indirectly drive rotation of the rotatable component.

10. The system of claim 8 or 9, wherein the prime mover is configured to drive rotation of the rotatable test component indirectly via one or more of: a drive train, a shaft, a coupling, and a torque transducer.11 . The system of any of claims 8 to 10, wherein the system is a tribological testing rig.

12. A method of performing one or more tribo-dynamic measurements on a rotatable test component, the method comprising: coupling a prime mover to a rotatable test component; driving rotation of the rotatable test component via the coupled prime mover; decoupling the prime mover from the rotating test component; and performing one or more measurements on the decoupled rotating test component.

13. A method of performing modal testing comprising the method of claim 12.

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