Transmission for a self-propelled machine and wheeled self-propelled machine, in particular a lawn mower

A transmission for a self-propelled machine comprising:

• an endless transmission (1) with a belt (2) between a drive pulley (3) mounted on a primary motor shaft and a driven pulley (4) carried by an input shaft (5) of a clutch engaging mechanism (7) having an output shaft (6) coupled to wheels (20) of the machine,
• the clutch engaging mechanism (7) being disposed within a housing (19) mounted oscillably about the output shaft (6) of the clutch engaging mechanism (7) in the direction of tension or relaxation of the belt (2) of the endless transmission under the action of a pivoting lever (13) that projects from the housing (19),
• the lever (13) being subject to a control member (10) of the clutch engaging mechanism so as to give rise, in a first instance, to a clutch engaged condition of the clutch engaging mechanism (7), then, in a second instance, to tensioning of the belt (2) to obtain movement of the machine,
• wherein a variation of a speed of the machine is obtained by variation of the tension applied to the belt (2) with the help of the pivoting lever (13) disposed outside the clutch engaging housing (19), so as to avoid any speed change box with multiple ratios within said housing (19), and
• wherein the clutch engaging mechanism (7) comprises a sleeve (8) movable axially under the influence of the control member (10) for clutch engagement and secured in rotation to the output shaft (6) of the clutch engaging mechanism, said sleeve (8) being arranged and adapted to coact by toothed engagement with a driven member that is mounted freely in rotation on said output shaft (6), said toothed wheel (9) coming into engagement with an endless screw constituting the input shaft (5) of the clutch engaging mechanism (7).