Gear rattle dynamics: lubricant force formulation analysis on stationary conditions

Abstract

Gear rattle is a common and inherent phenomenon to multi-stage-constant-mesh gearboxes, since this kind of transmission consist of two different types of gear pairs: active and inactive stages. The former is in charge of transmitting the energy, whilst the latter, although its teeth are engaged, is loosely connected to the output shaft. Gear rattle problematic resides in undesirable impacts and fluctuations in the inactive gears provoked by their interaction with the active stage, leading to vibrations which can produce fails in elements connected or belonging to the gearbox. In this regard, understanding the lubricant role is crucial, being this aspect the key to comprehend the dynamic behaviour of low-loaded gear transmissions and to palliate these phenomenon consequences as the ultimate goal of this research. Within this context, in this work, six formulations, which consider both entraining and squeeze fluid effects, were implemented in gear transmission models previously developed by the authors in order to calculate the hydrodynamic forces. Special attention was paid to the fluid viscosity influence on the dynamic behaviour under stationary conditions.