Tapered Roller Bearing architecture with Optimized Shoulder to operate at high speed

Daniele Podda

Summary

Tapered roller bearings are well known as robust and reliable machine elements, offering an optimal solution in terms of load-carrying capacity and weight, particularly, in rotating applications involving significant axial loads. Those bearings have found extensive use across a variety of applications, but they exhibit also technical limitations at elevated rotational speeds. Under such conditions, the retaining shoulder that prevent the pull-out of the rolling elements is subjected to substantial sliding phenomena, leading to accelerated wear and, in some cases, critical thermal stabilization issues.

Since 2021, the Transmission System Design Department of Leonardo Helicopter Division (LHD) has been engaged in the development of an innovative tapered roller bearing architecture with optimized shoulder to operate at 2’000’000 n*dm.

The development originated from a study aimed at enhancing the performance of an input stage for a main gearbox under loss-of-lubrication scenarios. The investigation revealed that the most promising solution for supporting a high-speed pinion while minimizing power losses was a bearing typically employed in lower speed ranges because limited by internal friction.

This paper presents the technical solution, detailing the kinematic behavior of the bearing and providing an estimation of the associated power losses.