A transmission between a driving primary shaft and an outlet shaft of a self-propelled machine, includes a housing within which there are housed, at least in part: a stepdown mechanism; two clutch mechanisms, one being progressive and the other being non-progressive with a movable dog; and a clutch control device including first and second clutch control elements. The first and second contact parts are connected to the light emitting device to apply a first current to the light emitting device. Also, the intercord distances T1 to Tk have a relationship such that T1\u2266T2\u2266. The invention includes read channel optimized parameters for at least temperature ranges within the embedded disk controller, which are updated in the user’s operating environment during idle time providing the self-vaccine.