Abstract: A transmission can convert a single speed, single rotary directional input, to a continuously variable clockwise or anticlockwise directional output. This effect can be achieved without disengaging the output shaft from the input shaft. The transmission includes a pair of epicycloidal gear trains having sun gears on a common shaft. A ring gear in the first gear train drives a planet gear in the second gear train. A variable speed drive drives a planet gear in the first drive train. The transmission has particular application in vehicles which require an engine to operate at or close to an optimum speed to match its operational requirements. Similarly engines such as turbines or electric motors which can operate efficiently within a speed range and with a single rotational direction can be used with the transmission to provide power to systems requiring a variety of speeds and reversing characteristics.