DEVICE FOR CHANGING THE TRANSMISSION RATIO BETWEEN A TURBINE SHAFT AND A STARTER/GENERATOR SHAFT OF AIRCRAFT ENGINE

摘要

The invention relates to a device for changing the transmission ratio between a turbine shaft and a starter/generator shaft of an aircraft engine, said device including: first and second stationary pinions (23, 24) held by the shaft (22) of the starter/generator (20); first and second idle pinions (13, 14) held by the turbine shaft and respectively engaging with the first and second stationary pinions so as to define different engagement ratios; a switching sleeve (50) inserted between the idle pinions and mechanically coupled with the turbine shaft, the switching sleeve being translatable over said turbine shaft between two coupling positions; and a means for having the switching sleeve automatically translate from one to the other of the coupling positions thereof when the sum of the torques between the turbine shaft and the starter/generator shaft changes from positive to negative or vice versa.