Patent ID: 7669702

Claim:
A transmission box ( 3 ) for a wheeled machine ( 1 ), comprising: a motor input shaft ( 4 ) disposed at least partially within the transmission box, which is stationary, the motor input shaft ( 4 ) driving a drive wheel ( 8 ) to actuate at least one drive shaft ( 9 A, 9 B) of at least one wheel ( 2 A, 2 B) of the machine ( 1 ); and a clutch mechanism ( 13 ) disposed between the drive wheel ( 8 ) and the drive shaft ( 9 A, 9 B) of the wheel ( 2 A, 2 B), the clutch mechanism ( 13 ) being actuated by driving in rotation of the drive wheel ( 8 ) and deactuated by driving in rotation of the drive shaft ( 9 A, 9 B) of the wheel ( 2 A, 2 B) when the motor input shaft ( 4 ) is stopped or when a speed of rotation of the drive shaft ( 9 A, 9 B) is greater than a speed of rotation of the drive wheel ( 8 ), each wheel drive shaft being in an inactivated condition of the corresponding clutch mechanism, free to turn in either direction of rotation, wherein the transmission box ( 3 ) contains, on opposite sides of the drive wheel ( 8 ), the clutch mechanism ( 13 ) comprising two clutch mechanisms ( 13 ) each coacting with one drive shaft ( 9 A, 9 B) to permit a free wheeling of one end or the other wheel or both of the wheels ( 2 A, 2 B), each clutch mechanism ( 13 ) is actuated by driving in rotation the drive wheel ( 8 ) and axial movement of at least one mobile member ( 15 , 15 ′) on said drive shaft ( 9 A, 9 B), the mobile member ( 15 , 15 ′) movable axially on or along the drive shaft ( 9 A, 9 B) carrying ramps ( 17 , 17 ′) coacting with a secured member ( 18 , 19 ) secured in rotation with said drive shaft ( 9 A, 9 B) to permit, in a clutching phase, securement in rotation between the ramps ( 17 , 17 ′) of the mobile member ( 15 , 15 ′) and the secured member ( 18 , 19 ) secured in rotation with the drive shaft ( 9 A, 9 B) and then the transmission of the movement of rotation of the mobile member ( 15 , 15 ′) to the drive shaft ( 9 A, 9 B), and in an unclutching phase a release of connection between the ramps ( 17 , 17 ′) of the mobile member ( 15 , 15 ′) and the secured member ( 18 , 19 ) secured in rotation to the drive shaft ( 9 A, 9 B), the mobile member ( 15 , 15 ′) including a clutch plate ( 15 ) provided with a brake ( 21 ) acting permanently on an angular speed of said clutch plate ( 15 ) to facilitate and permit the clutching and the unclutching phases, the drive wheel ( 8 ) and the axially mobile member ( 15 , 15 ′) of each clutch mechanism ( 13 ) carry on their facing surfaces, ramps ( 14 , 16 , 16 ′) which coact, during the clutching phase, for the axial movement of the mobile member ( 15 , 15 ′) in a first direction for securement with the drive shaft ( 9 A, 9 B), said ramps ( 14 , 16 , 16 ′) being constituted by at least one of flanks of teeth or crenalations, projecting from said surfaces, and each tooth of the driven wheel ( 8 ) or of the axially mobile member ( 15 , 15 ′) is an asymmetric tooth.