Patent ID: 8133155

Claim:
A rotorcraft drive system comprising: a rotor system comprising one or more rotors; one or more engines, each engine of the one or more engines being coupled to the rotor system through a multi-ratio transmission, the multi-ratio transmission comprising: an output shaft coupled to the rotor system; an input shaft coupled to a respective engine of the one or more engines; a high speed clutch integrated into a high speed gear train; and a low speed clutch integrated into a low speed gear train, wherein the high speed clutch and the low speed clutch are freewheeling clutches without a friction plate and are capable of disconnecting the output shaft and the input shaft in an overrunning condition when the output shaft spins faster than the input shaft; and wherein the multi-ratio transmission shifts between the high speed gear train and the low speed gear train by engaging or disengaging the high speed clutch and modulating speed of the coupled engine.