A low noise level is an important quality feature in modern gearboxes for passenger cars. But a troublesome
noise can have many causes. The noise origination and transmission is amongst others affected by the design
layout, by the actual deviations of the components, by the assembly of the components and also by the
mounting situation of the complete gearbox.
Damages, form errors and displacement errors or ripples are often present on the flanks of a gear, ifit is found
to be the cause of problems in a noise check. Especially ripples or ‘ghost frequencies’ of a gear are
problematic, because up to now they rarely can be detected on a gear measuring device but only in a relative
complex single-flank roll checking procedure.
A new evaluation method now allows to identify and to describe ripples on the flanks of gears based on the
results of a normal gear measurement. The deviation curves were approximated by sine functions, the results
are displayed graphical and by characteristic values. A combination of the deviation of each measured point
with its rotation angle allows an evaluation equal to a rlling with the mating gear. The results show a very good
correlation to a noise check and to a single-flank roll check.