Investigation of bearings overloads due to misaligned splined shafts

Bearings may be subjected to overloads due to shaft unwanted loads, caused, as an example, by tiling moments related to spline coupling misalignment. Misalignment is mainly generated by manufacturing of mounting errors (due to machining tolerances) or by the transmission working conditions. These kind of overload is critical because may reduce both bearing life and system efficiency, moreover it is quite complicated to be evaluated. In this work, the overload generated on bearings supporting a misaligned splined shafts have been investigated by means of a commercial simulation software (Romax Designer). The simulations have been performed considering a standard transmission scheme composed of two shafts connected by a spline coupling and supported by four roller bearings (two for each shaft), mounted in isostatic configuration. The effect of spline coupling teeth microgeometry has been taken into account along with the misalignment angle magnitude and the torque level. In particular, the influence of these parameters on teeth contact pressure has been evaluated, as tilting moment is mainly driven by the contact pressure distribution among engaging teeth and by the position of maximum pressure distribution along teeth in axial direction. Results obtained in this work may be useful to designers, suggesting some basic criteria to reduce the bearings overload, allowing designing more reliable machines.