A combined theoretical and experimental investigation is made
into the causes of premature gear failures which had occurred in the
complex and lighly loaded gear trains of an industrial textile
machine. A comprehensive review of previous relevant work identifies
the problem as one of torsional vibratory impact excited by gear
An extension of the dynamic stiffness method is developed for
the analysis of forced vibration response due to relative displacement,
harmonic excitation imparted by transmission error components. The
technique is then applied to a generalised mathematical model of the
complete machine in which typical production distributions of gear
error magnitude and relative phasing are inserted. Gear-tooth
dynamic loads are computed at every mesh for a number of different
machine configurations over the operating speed range. The influence
of selected inertia, flexibility and damping elements is demonstrated.
A novel technique employing magnetic drums is devised and
evaluated for the direct measurement of-relative motions in a meshed
pair of oscillating gears. Automatic compensation is provided for
transmission error and mounting eccentricity. A further direct
technique is reported for the detection of tooth impacts and is based
on the change in electrical resistance between meshing teeth as the
contact pressure varies.
Measurements in a multi-gearbox experimental rig demonstrated
that the gears described non-linear motions, involving excursions
through the backlash and heavy impacts on both drive and reverse faces.
Theoretical predictibns of dynamic loading distribution within
machines show reasonable compatibility with patterns of gear
failure recorded in service, even though the analysis does not allow for system non-linearities.
Machine design considerations are examined in retrospect from
a dynamics standpoint. Past and present designs are appraised and
possible alternatives to these are briefly discussed.
Finally, the salient factors identified in the investigation
are summarised and recommendations made for future work.
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.