Abstract: A centrifugally controlled two-speed accessory drive for operation of one or more automotive vehicle accessories to provide a two-stage operation depending on the engine speed, the drive including a gear box secured to the face of the accessory and having an input shaft driven by a pulley and belt from the engine, an output shaft driving the accessory, and a planetary gear set connecting the shafts. The gear set includes a sun gear connected to the output shaft, a ring gear rotatably mounted in the gear box and a planet carrier rotatable with the input shaft and mounting a plurality of planetary gears between the sun gear and ring gear. A cone clutch engages the ring gear to ground it through a Belleville spring, piston and fulcrum, and centrifugal weights act to unground the ring gear; a one-way clutch between the shafts allows the output shaft to overrun the input shaft when the ring gear is grounded and rotate the output shaft with the input shaft as a unit when the ring gear is ungrounded.