Improved transmission device for hybrid aircraft

A transmission device for a hybrid aircraft, particularly a helicopter, the aircraft comprising a turbomachine including at least one gas generator, a free turbine rotationally driven by a stream of gas generated by the gas generator, and a main rotor, the transmission device comprising a first reversible electric machine able to be coupled to a shaft of the free turbine by way of a first deactivatable coupling means, and to the main rotor, and a second reversible electric machine able to be coupled to a shaft of the gas generator by way of a second deactivatable coupling means, and to be coupled to the main rotor by way of a third deactivatable coupling means, the second deactivatable coupling means being configured to be activated when the second electric machine rotates in a first direction of rotation, and the third deactivatable coupling means being configured to be activated when the second electric machine rotates in a second direction of rotation opposite to the first direction of rotation.