TWO-SPEED PLANETARY FRICTION ACCESSORY DRIVE

BAEI 0104 PUS 90041 A planetary friction roller drive (30, 66, 84, 26)adapted particularly for use in driving automotive accessories such as an alternator wherein provision is made for delivering engine torque to the ring roller element (26) of the planetary friction drive and for connecting drivably the sun roller element (30) of the friction drive to a driven accessory such as an alternator and wherein a torque flow path characterized by two speed ratios is effected by a compound planetary carrier assembly (50) as a preload at the friction drive contact locations between the planetary rollers (66, 84) and the ring roller element (30) and between the planetary rollers (66, 84) and the sun roller element (30) of the planetary assembly is established by a preload spring (134) acting in a tangential direction, the reaction torque for the planetary friction drive being established by a selectively engageable brake (136) acting on the sun roller element (30) thus effecting a ratio transition from unity.