Spur Gearbox Research Articles

The investigation of the condition and faults of a spur gearbox using vibration and wear debris analysis techniques

The aim of this work is to investigate the effectiveness of combining both vibration analysis and wear debris analysis in an integrated machine condition monitoring maintenance program. To this end, a series of studies was conducted on a spur gearbox test rig. After a test under normal condition was conducted to obtain the baseline information of the test rig, a number of different machine defect conditions were introduced under controlled operating conditions, corresponding to (i) constant overload conditions and (ii) cyclic load conditions. The data provided by wear debris analysis was compared with vibration analysis spectra in order to quantify the effectiveness of both vibration analysis and wear debris analysis in predicting and diagnosing machine failures. The paper discusses the use of a numerical approach for wear debris analysis, facilitated by the use of a laser scanning confocal microscope (LSCM). The correlation between wear debris and vibration analysis techniques is discussed, and the usefulness of the numerical descriptors for wear debris analysis is evaluated.

Identification of the acoustic emission source during a comparative study on diagnosis of a spur gearbox

Condition monitoring of gears with vibration analysis is well established whilst the application of acoustic emission (AE) to gear defect diagnosis and monitoring is still in its infancy. This paper details results of an experimental programme to ascertain and validate the applicability of AE to seeded gear defect identification. Furthermore, comparisons are made to vibration diagnosis. As a direct consequence of the experimental programme, the relationship between temperature, oil film thickness and AE activity were investigated. It is shown that similar to the lubricant film thickness between non-conforming surfaces under isothermal conditions, AE activity is not influenced by load. Limitations of applying AE to seeded defect identification are presented and it is concluded that the source of AE activity is attributed to asperity contact.

Effect of tooth backlash and ball bearing deadband clearance on vibration spectrum in spur gear boxes

An analytical model is presented for studying the effect of tooth backlash and ball-bearing deadband clearance (clearance between bearing outer ring and its housing) on vibration spectrum of spur gear boxes. Included in the model are coupled torsional-lateral vibrations of the shafts, time-varying tooth backlash (backlash is a function of operating center distance), mesh stiffness (stiffness is calculated based on the bending, shear, axial, and Hertzian contact strain energies of the tooth that is treated as a cantilever of involute shape), and Hertzian damping at mesh, friction between meshing teeth, and interaction between gear box casing and internals. The bearing–housing reaction forces are calculated with consideration of bearing clearance and system vibrations. The above parameters are accounted for with allowance for number of teeth pairs sharing the load to alternate between one and two. The analysis is applied to a single stage gear box and equations of motion are deduced using Newton’s laws of motion and numerically integrated using Runge–Kutta method. The gear box casing velocities in time domain are transformed into frequency domain (vibration spectrum) using Fast Fourier Transform (FFT). This was done for different values of tooth backlash and bearing clearance and samples of the results are shown. This model provides an analysis procedure for predicting effect of tooth wear (wear affects backlash) and bearing deadband clearance on gear box vibration spectrum.

Effect of backlash and sleeve bearing clearance on the vibration spectrum of high‐speed spur gear boxes

An analytical model is presented to simulate the effects of tooth backlash and sleeve bearing clearance on the vibration spectra of high‐speed spur gear boxes. Elasticity in bending and torsion of the shafts, time‐varying mesh stiffness, tooth backlash, and Hertzian mesh damping, friction between engaged teeth, and interaction between gear box casing and internals are accounted for. During contact between journal and bearing, where time‐varying contact stiffness with consideration of damping at contact point is accounted for, bearing clearance, system vibration, and bearing forces are calculated. The analysis is applied to a single stage gear box and equations of motion are numerically integrated to obtain system response in the time domain. The response is transformed into frequency domain using a fast Fourier transform (FFT) algorithm and samples of the results are shown for different values of backlash and bearing clearance.

On the vibration spectrum of high‐speed spur gear boxes

An analytical model is presented to simulate the effect of tooth backlash and ball‐bearing radial clearance on the vibration spectrum of high‐speed spur gear boxes. Included in this model are elasticity in bending and torsion of the shafts, friction between meshing teeth, interaction between gear box casing and internals, and time‐varying tooth backlash, mesh stiffness (stiffness is calculated based on the strain energies of the tooth, which is treated as a cantilever beam of involute shape), and Hertzian mesh damping. The bearing loads are calculated with consideration of shaft oscillations and speed, bearing radial clearance, ball centrifugal force, and bearing outer ring oscillations. To demonstrate the model, a single stage gear box is analyzed, and equations of motion are numerically integrated to obtain system response in the time domain. This response is transformed into the frequency domain using a fast Fourier transform (FFT) algorithm and samples of the results are shown for different values of backlash and bearing clearance.

Thermal Analysis of a Spur Gearbox Part 2: Transient State Finite Element Analysis of the Gearbox Casing

In Part 1 of this paper measured and computed steady state temperatures for a spur gearbox casing have been compared, and the approach to determining the thermal boundary conditions is presented. In Part 2 this approach is extended to two different transient problems. The first is for continuous running from start-up until the steady state conditions are attained, and the second is for a start-stop-restart cycle in an attempt to simulate intermittent running. The finite element (FE) results and derivation of the boundary conditions are both described.

Thermal Analysis of a Spur Gearbox Part 1: Steady State Finite Element Analysis

The accuracy of previously published thermal analyses of machine tools has been severely limited by imprecise thermal boundary conditions, in particular the values and distribution of heat inputs and heat-transfer coefficients. This paper describes an attempt to overcome some of the difficulties by determining the thermal boundary conditions for calculating the temperatures in a gearbox using the finite element method. A spur gearbox test rig has been designed and constructed, and a finite element model of the test gearbox developed. Temperature measurements and lubricant flow observations from experimental work have been combined with relevant theory to derive the boundary conditions. In the first part of this paper the experimental work and finite element steady state results are described. Sufficient agreement is evident between the two sets of results to indicate that the approach adopted here could be usefully extended to the analysis of other similar problems.