Abstract: A novel power transmission mechanism is provided in which a wide variety of both forward and reverse speed ratios are achieved by coupling two or more planetary gearsets in a unique way. Power input is applied to one of the sun gear, ring gear and planet carrier of the first planetary gearset while another of the gears is maintained stationary and output is taken from one of the sun gear, ring gear and planet carrier not maintained stationary in the first gearset (except that, when power is transmitted to the ring gear, the planet carrier is not maintained stationary). The procedure then is repeated for the second and any subsequent planetary gearset which usually has an overall different gear ratio from the first planetary gearset. Each planetary gearset is capable of producing four forward output ratios and one reverse ratio. Because of the different ratios of the various gearsets, multiple ratios of output are attainable.