Epicyclic Gear Transmission Error - The Importance of Controlling Tolerances

It is well known that the spacing of planets in an epicyclic gear set is an important “macro” design feature that is used to balance planet load sharing, increase gear life and reduce gear whine.

What is less understood is how the manufacturing tolerance of the position of the planet pins within the carrier, a “micro” phenomenon, affects the gear whine.

This paper describes an analysis technique that can predict system level behaviour and shows that the inherent variability in the manufacturing processes has a very significant effect on the TE and thus generated gear whine.

The manufacturing variability causes radial, circumferential and tilt displacements of planet gears - these phenomenon are all investigated.