Analysis of the mechanical behaviour of planetary gears for power transmissions

Tooth separation and wedging remain key concerns in planetary gears sets design. These may lead to anomalous in-service conditions and cause premature tooth damage and bearings failure. Damage is related to planets loads sharing which in turn depends on assembly errors and functional parameters of the used design solutions. This paper assesses the effects of the assembly errors and planets bearings clearance on the planets load sharing. The analysis focuses planetary gears sets used in wind power plants where these issues are particularly crucial. The effects of randomly distributed bearings clearances and misalignments are investigated using a simplified probabilistic approach. The study, carried out by means of a two-dimensional lumped-parameter model enabling both tooth separation and wedging, demonstrates a significant impact of the non uniform clearances distributions and assembly errors on the load sharing.