Patent ID: 7555968

Claim:
Transmission device between a primary drive shaft and an output shaft ( 1 ), comprising: a reduction gear mechanism; a clutch mechanism; a housing ( 2 ) at least partially housing the reduction gear mechanism, the reduction gear mechanism comprising an engine-driving element ( 3 ) meshed with a driven element ( 4 ), the driven element ( 4 ) being configured to be coupled to and uncoupled from said output shaft ( 1 ) by the clutch mechanism activated/deactivated by axial movement of the driven element ( 4 ) on the output shaft, wherein the clutch mechanism, when retracted to the disengaged position, assumes the shape of a clutch cover plate ( 6 ) that is integral in rotation with the output shaft ( 1 ), the clutch cover plate ( 6 ) being provided, on a face opposite the driven element ( 4 ), with ramps designed to work during an engagement phase with ramps supported by the driven element ( 4 ), whereby this engagement is obtained by axial movement of the driven element ( 4 ) on the shaft ( 1 ) in the direction in which the driven element ( 4 ) moves toward said clutch cover plate ( 6 ), whereby the axial movement is controlled by an actuating element with manual control, and wherein the actuating element is, unless there is control input from a driver, retracted to an inactive position corresponding to the disengaged position of the clutch mechanism and wherein there is provided, inserted between clutch cover plate ( 6 ) and driven element ( 4 ), a spring ( 9 ) that tends to retract the driven element ( 4 ) into a position away from the clutch cover plate ( 6 ) that corresponds to a disengaged position.