Abstract: A variable-speed drive is activated by an actuator controlled by an electronic control system on the basis of engine and vehicle operating parameters. The control system according to the present invention is characterized by the fact that it comprises an actuating member located and operated manually on the gear lever; a detector for detecting the position of the actuating member and generating electric signals proportional to the same; and at least an electric circuit for generating electric signals for controlling and setting the actuator to predetermined positions corresponding to velocity ratios of the variable-speed drive proportional to the aforementioned electric control signals.

Abstract: The system includes a plurality of sensor devices each arranged to monitor a respective physical or operating magnitude of apparatus, a device or a member of the vehicle, and to provide corresponding electrical signals. An acoustic signal generator provides a plurality of acoustic characterizing signals, indicative of corresponding predetermined operating conditions, and a plurality of acoustic level signals indicative of corresponding predetermined levels of importance attributable to the operating conditions. A processing unit detects on the basis of signals provided by the sensor devices the operating conditions of the vehicle and attaches in a predetermined manner, a level of importance to each operating condition identified, and supplies to the acoustic signal generator electrical control signals for causing the output of an acoustic signal comprising, in succession, the level signal and the characterizing signal associated with the operating condition detected.