3000-HP Roller Gear Transmission Development Program, Volume II. Design Report

The development of the roller gear drive indicated potential gains in the overall operational efficiency of turbine-powered helicopters. This report presents the design effort involved in the development of the Sikorsky S-61 roller gear transmission. The roller gear drive is a combination of the roller transmission, which transmits power through friction, and a conventional geared planetary arrangement. This report covers the initial design of the S-61 roller gear transmission wherein the number of reduction stages, their locations and the reduction ratio of the roller gear unit are determined. Various types and layouts of transmissions are discussed. The finalized layout, which receives 3, 700 hp from twin turbines and transmits 3,000 hp to the main rotor, incorporates a 19.85:1 roller gear unit as the final stage in a three-stage reduction transmission. The detail design of the major components is discussed, and a stress analysis is presented in the appendixes. A calculated efficiency of 98.9% for the roller gear unit and 96.5% for the transmission is comparable to high- reduction-ratio transmissions of conventional design. Dynamic testing of the transmission will be conducted during later phases of the program whereby the efficiency of the transmission will be measured. See also Volume 3, ADA014135.