Examination of Critically Loaded Bearings in the Pericyclic Transmission

Open Access
Cameron, Zachary A
Graduate Program:
Aerospace Engineering
Master of Science
Document Type:
Master Thesis
Date of Defense:
April 08, 2017
Committee Members:
  • Edward Smith, Thesis Advisor
  • Nutational Gearing
  • Pericyclic Transmission
  • Rotorcraft
  • Bearings
  • Dynamic Moment
ABSTRACT The rotorcraft industry has set rigorous goals for improvements in range, load capacity, and operational speed for the next generation of rotorcraft. In order to achieve these goals many facets critical to the operation of rotorcraft will need improvements. One such facet is the transmission system, which will need reductions in overall weight while maintaining the same level of efficiency and reliability. The Pericyclic Variable Transmission (PVT) provides a viable option for the future of rotorcraft transmission, offering both high reduction ratios and high power density. Previous work has examined transmission feasibility, variable speed power flow, and gear tooth loading and meshing conjugacy. A critical area that required development was the loading and power flow through the main Pericyclic Motion Converter (PMC) bearing set. This work examines impact of transmission geometry on operation, establishes a method for determining both static and dynamic bearing loads, and evaluating methods for limiting excessive loads. Calculated loads have been used to determine key stress and strain values of the bearing rollers and balls that determine approximate size, and weight of these critical bearings and provides an estimate of total transmission weight. These calculations were carried out for a 40:1 reduction ratio pericyclic at 1,000HP with an input speed of 12,000rpm. Results show that the pericyclic is valid for low nutation angles and that decreases in component weight will lead to overall component loading.