EVALUATION STUDY OF BALANCED LOAD PLANETARY TRANSMISSION AND DESIGN OF 250-HORSEPOWER UNIT WITH 4000-HOUR TIME BETWEEN OVERHAUL (TBO)

This report presents a complete review of the parametric design and computer studies performed to evaluate the Bergen Research Compound Planetary Transmission concept in three configurations for a helicopter transmission. All three concepts embody design arrangements which assure uniform load division with multiple compound planetary gears. Uniform loading is accomplished by balancing the primary and secondary meshing point positions through low rate springing. These systems stabilize at the gear mesh positions of load path equalization. Design are established for typical power ranges using consistent gear and bearing design factors. Both 1000 and 4000 hour time before overhaul design factors are studied to determine their feasibility and design trade off requirements. The Phase I study results are applied in Phase II to the preferred design concept through completion of a specific layout and detail design. This 250 Horsepower4000 Hour design is suitable for fabrication and life testing.