Patent ID: 7665589

Claim:
A transmission box ( 3 ) for a wheeled machine ( 1 ), comprising: disposed at least partially within said box ( 3 ), a motor input shaft ( 4 ) driving a drive wheel ( 8 ) to actuate at least one drive shaft ( 9 ) of at least one wheel ( 2 A, 2 B) of the machine ( 1 ); and a clutch mechanism ( 13 ) being disposed between the drive wheel ( 8 ) and the drive shaft ( 9 ), the clutch mechanism ( 13 ) being actuated by driving in rotation of the drive wheel ( 8 ) and axial movement of at least one member ( 15 , 15 ′) on said drive shaft ( 9 ) and deactuated by driving in rotation the drive shaft ( 9 ) when the input shaft ( 4 ) is stopped or when the speed of rotation of the drive shaft ( 9 ) is greater than a speed of rotation of the drive wheel ( 8 ), wherein the member ( 15 , 15 ′), movable axially on or along the drive shaft ( 9 ), is a clutch plate ( 15 , 15 ′) disposed between the drive wheel ( 8 ) and a member ( 18 , 19 ) secured in rotation with the drive shaft ( 9 ), wherein the clutch plate ( 15 , 15 ′) is provided, on each of its surfaces, with ramps ( 16 , 17 , 17 ′), wherein the ramps ( 16 ) on one surface of the clutch plate ( 15 , 15 ′) coact, during the clutching phase, with ramps ( 14 ) of the drive wheel ( 8 ), for axial movement of the clutch plate ( 15 , 15 ′) in a first direction of securement in rotation with the member ( 18 , 19 ) carried by the drive shaft ( 9 ) and secured in rotation with the latter and, as a result, a transmission of the movement of rotation of the clutch plate ( 15 , 15 ′) to the drive shaft ( 9 ), said ramps ( 14 , 16 , 16 ′) being constituted by at least one of flanks of teeth or crenalations projecting from facing surfaces of the drive wheel ( 8 ) and the clutch plate ( 15 , 15 ′), each tooth of the drive wheel ( 8 ) or of the axially movable clutch plate ( 15 , 15 ′) being an asymmetric tooth, the ramps ( 17 , 17 ′) on the other surface of the clutch plate ( 15 , 15 ′) coacting during the unclutching phase with the member ( 18 , 19 ) carried by the drive shaft ( 9 ) and secured in rotation with this latter to give rise, by axial movement in direction opposite said clutch plate ( 15 , 15 ′), a disengagement between the ramp or ramps ( 17 , 17 ′) of the movable clutch plate ( 15 , 15 ′) and the member ( 18 , 19 ) secured in rotation with said drive shaft ( 9 ), to a free wheeling of the drive shaft, and that the clutch plate ( 15 , 15 ′) movable axially on the drive shaft ( 9 ) of the wheels is provided with a friction brake ( 21 ) acting on an angular speed of said clutch plate ( 15 , 15 ′) to facilitate or permit phases of clutching and unclutching, the friction brake ( 21 ) being constituted by a spring blade acting by friction on a section of the axially movable clutch plate ( 15 , 15 ′).